![BluRayLaser](https://upload.wikimedia.org/wikipedia/commons/7/71/BluRayLaser.JPG)
In
computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...
, an optical disc drive is a
disc drive that uses
laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The fi ...
light or electromagnetic waves within or near the visible
light spectrum
The electromagnetic spectrum is the range of frequency, frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energy, photon energies.
The electromagnetic spectrum covers electromagnetic waves with f ...
as part of the process of reading or writing data to or from
optical disc
In computing and optical disc recording technologies, an optical disc (OD) is a flat, usually circular disc that encodes binary data (bits) in the form of pits and lands on a special material, often aluminum, on one of its flat surfaces. ...
s. Some drives can only read from certain discs, but recent drives can both read and record, also called burners or writers (since they physically burn the organic dye on write-once CD-R, DVD-R and BD-R LTH discs).
Compact disc
The compact disc (CD) is a digital optical disc data storage format that was co-developed by Philips and Sony to store and play digital audio recordings. In August 1982, the first compact disc was manufactured. It was then released in Oc ...
s,
DVD
The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kind ...
s, and
Blu-ray
The Blu-ray Disc (BD), often known simply as Blu-ray, is a digital optical disc data storage format. It was invented and developed in 2005 and released on June 20, 2006 worldwide. It is designed to supersede the DVD format, and capable of st ...
discs are common types of optical media which can be read and recorded by such drives.
Drive types
, most of the optical disc drives on the market are
DVD-ROM
The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kind ...
drives and
BD-ROM drives which read and record from those formats, along with having
backward compatibility
Backward compatibility (sometimes known as backwards compatibility) is a property of an operating system, product, or technology that allows for interoperability with an older legacy system, or with input designed for such a system, especiall ...
with CD,
CD-R
CD-R (Compact disc-recordable) is a digital optical disc storage format. A CD-R disc is a compact disc that can be written once and read arbitrarily many times.
CD-R discs (CD-Rs) are readable by most CD readers manufactured prior to the i ...
and
CD-ROM discs; compact disc drives are no longer manufactured outside of audio devices. Read-only DVD and Blu-ray drives are also manufactured, but are less commonly found in the consumer market and mainly limited to media devices such as
game consoles and disc media players. Over the last ten years,
laptop computer
A laptop, laptop computer, or notebook computer is a small, portable personal computer (PC) with a screen and alphanumeric keyboard. Laptops typically have a clam shell form factor with the screen mounted on the inside of the upper li ...
s no longer come with optical disc drives in order to reduce costs and make devices lighter, requiring consumers to purchase external optical drives.
Appliances and functionality
Optical disc drives are an integral part of standalone appliances such as
CD player
A CD player is an electronic device that plays audio compact discs, which are a digital optical disc data storage format. CD players were first sold to consumers in 1982. CDs typically contain recordings of audio material such as music or audio ...
s,
DVD player
A DVD player is a device that plays DVDs produced under both the DVD-Video and DVD-Audio technical standards, two different and incompatible standards. Some DVD players will also play audio CDs. DVD players are connected to a television to ...
s, Blu-ray Disc players,
DVD recorder
A DVD recorder is an optical disc recorder that uses optical disc recording technologies to digitally record analog or digital signals onto blank writable DVD media. Such devices are available as either installable drives for computers o ...
s, certain desktop video game consoles, such as
Sony PlayStation 4
The PlayStation 4 (PS4) is a home video game console developed by Sony Interactive Entertainment. Announced as the successor to the PlayStation 3 in February 2013, it was launched on November 15, 2013, in North America, November 29, 2013 in ...
,
Microsoft Xbox One
The Xbox One is a home video game console developed by Microsoft. Announced in May 2013, it is the successor to Xbox 360 and the third base console in the Xbox series of video game consoles. It was first released in North America, parts of ...
,
Nintendo Wii U
The Wii U ( ) is a home video game console developed by Nintendo as the successor to the Wii. Released in late 2012, it is the first eighth-generation video game console and competed with Microsoft's Xbox One and Sony's PlayStation 4.
The W ...
,
Sony PlayStation 5
The PlayStation 5 (PS5) is a home video game console developed by Sony Interactive Entertainment. Announced as the successor to the PlayStation 4 in April 2019, it was launched on November 12, 2020, in Australia, Japan, New Zealand, North Ame ...
and
Xbox Series X
The Xbox Series X/S are home video game consoles developed by Microsoft. They were both released on November 10, 2020, as the fourth generation Xbox, succeeding the Xbox One. Along with Sony's PlayStation 5, also released in November 2020, ...
and also in older consoles, such as the
Sony PlayStation 3
The PlayStation 3 (PS3) is a home video game console developed by Sony Computer Entertainment. The successor to the PlayStation 2, it is part of the PlayStation brand of consoles. It was first released on November 11, 2006, in Japan, November ...
and
Xbox 360
The Xbox 360 is a home video game console developed by Microsoft. As the successor to the original Xbox, it is the second console in the Xbox series. It competed with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generati ...
, and certain portable video game consoles, such as
Sony PlayStation Portable
The PlayStation Portable (PSP) is a handheld game console developed and marketed by Sony Computer Entertainment. It was first released in Japan on December 12, 2004, in North America on March 24, 2005, and in PAL regions on September 1, 2005 ...
(using proprietary now discontinued
UMDs). They are also very commonly used in computers to read software and media distributed on disc and to record discs for archival and data exchange purposes.
Floppy disk drive
A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined w ...
s, with capacity of 1.44 MB, have been made obsolete: optical media are cheap and have vastly higher capacity to handle the large files used since the days of floppy discs, and the vast majority of computers and much consumer entertainment hardware have optical writers.
USB flash drive
Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply ( interfacing) between computers, peripherals and other computers. A bro ...
s, high-capacity, small, and inexpensive, are suitable where read/write capability is required.
Disc recording is restricted to storing files playable on consumer appliances (
films, music, etc.), relatively small volumes of data (e.g. a standard
DVD
The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kind ...
holds 4.7
gigabytes, however, higher-capacity formats such as multi-layer
Blu-ray Discs exist) for local use, and data for distribution, but only on a small scale; mass-producing large numbers of identical discs by pressing (replication) is cheaper and faster than individual recording (duplication).
Optical discs are used to
back up
In information technology, a backup, or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event. The verb form, referring to the process of doing so, is " back up", ...
relatively small volumes of data, but backing up of entire hard drives, which typically contain many hundreds of gigabytes or even multiple terabytes, is less practical. Large backups are often instead made on external hard drives, as their price has dropped to a level making this viable; in professional environments magnetic
tape drive
A tape drive is a data storage device that reads and writes data on a magnetic tape. Magnetic tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and a long archival stability.
...
s are also used.
Some optical drives also allow
predictively scanning the surface of discs for errors and detecting poor recording quality.
[QPxTool - check the quality]
List of supported devices by dosc quality scanning software ''QPxTool']
With an option in the
optical disc authoring
Optical disc authoring, including DVD and Blu-ray Disc authoring, is the process of assembling source material—video, audio or other data—into the proper logical volume format to then be recorded ("burned") onto an optical disc (ty ...
software, optical disc writers are able to
simulate the writing process on
CD-R
CD-R (Compact disc-recordable) is a digital optical disc storage format. A CD-R disc is a compact disc that can be written once and read arbitrarily many times.
CD-R discs (CD-Rs) are readable by most CD readers manufactured prior to the i ...
,
CD-RW
CD-RW (Compact Disc-Rewritable) is a digital optical disc storage format introduced in 1997. A CD-RW compact disc (CD-RWs) can be written, read, erased, and re-written.
CD-RWs, as opposed to CDs, require specialized readers that have sensi ...
,
DVD-R and
DVD-RW
DVD recordable and DVD rewritable are optical disc recording technologies. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only 'rewritable' discs are able to erase and rewrite data. Data is written ('bur ...
, which allows for testing such as observing the writing speeds and patterns (e.g.
constant angular velocity
In optical storage, constant angular velocity (CAV) is a qualifier for the rated speed of any disc containing information, and may also be applied to the writing speed of recordable discs. A drive or disc operating in CAV mode maintains a cons ...
,
constant linear velocity
In optical storage, constant linear velocity (CLV) is a qualifier for the rated speed of an optical disc drive, and may also be applied to the writing speed of recordable discs. CLV implies that the angular velocity (i.e. rpm) varies during an ...
and
P-CAV
In optical storage, constant angular velocity (CAV) is a qualifier for the rated speed of any disc containing information, and may also be applied to the writing speed of recordable discs. A drive or disc operating in CAV mode maintains a cons ...
and
Z-CLV
In optical storage, constant linear velocity (CLV) is a qualifier for the rated speed of an optical disc drive, and may also be applied to the writing speed of recordable discs. CLV implies that the angular velocity (i.e. rpm) varies during an ...
variants) with different writing speed settings and testing the highest capacity of an individual disc that would be achievable using
overburning
Optical disc authoring requires a number of different optical disc Hard disk recorder, recorder technologies working in tandem, from the optical disc media to the firmware to the control electronics of the optical disc drive.
Types of recordabl ...
, without writing any data to the disc.
Few optical drives allow simulating a
FAT32
File Allocation Table (FAT) is a file system developed for personal computers. Originally developed in 1977 for use on floppy disks, it was adapted for use on hard disks and other devices. It is often supported for compatibility reasons by ...
flash drive
A flash drive is a portable computer drive that uses flash memory. Flash drives are the larger memory modules consisting of a number of flash chips. A flash chip is used to read the contents of a single cell, but it can write entire block of cell ...
from optical discs containing
ISO9660
ISO 9660 (also known as ECMA-119) is a file system for optical disc media. Being sold by the International Organization for Standardization (ISO) the file system is considered an international technical standard. Since the specification is av ...
/
Joliet and
UDF file systems or
audio tracks (simulated as
.wav
files),
[Video]
"''Samsung ODD SE-S084D AV Connectivity"''
(published on September 14th 2010) for compatibility with most
USB
Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
multimedia
Multimedia is a form of communication that uses a combination of different content forms such as text, audio, images, animations, or video into a single interactive presentation, in contrast to tradit ...
appliances.
[TSSTcorp SE-208AB portable external DVD drive — User manual: Using ''"AV"'' mode (FAT32 file system simulation)]
(2011)
Key components
Form factors
Optical drives for computers come in two main form factors: ''
half-height
A drive bay is a standard-sized area for adding hardware to a computer. Most drive bays are fixed to the inside of a case, but some can be removed.
Over the years since the introduction of the IBM PC, it and its compatibles have had many form ...
'' (also known as ''desktop drive'') and ''slim type'' (used in
laptop computers and
compact desktop computers). They exist as both internal and external variants.
''Half-height'' optical drives are around 4 centimetres tall, while ''slim type'' optical drives are around 1 cm tall.
''Half-height'' optical drives operate upwards of twice the speeds as ''slim type'' optical drives, because speeds on slim type optical drives are constrained to the physical limitations of the
drive motor's rotation speed (around 5000
rpm
Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines.
Standards
ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...
) rather than the performance of the
optical pickup system.
Because ''half-height'' demand much more electrical power and a
voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to ...
of 12 V DC, while ''slim'' optical drives run on 5 volts, external ''half height'' optical drives require separate external power input, while external ''slim type'' are usually able to operate entirely on power delivered through a computer's
USB port
Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
. Half height drives are also faster than Slim drives due to this, since more power is required to spin the disc at higher speeds.
''Half-height'' optical drives hold discs in place from both sides while ''slim type'' optical drives fasten the disc from the bottom.
Half height drives fasten the disc using 2 spindles containing a magnet each, one under and one above the disc tray. The spindles may be lined with flocking or a texturized silicone material to exert friction on the disc, to keep it from slipping. The upper spindle is left slightly loose and is attracted to the lower spindle because of the magnets they have. When the tray is opened, a mechanism driven by the movement of the tray pulls the lower spindle away from the upper spindle and vice versa when the tray is closed. When the tray is closed, the lower spindle touches the inner circumference of the disc, and slightly raises the disc from the tray to the upper spindle, which is attracted to the magnet on the lower disc, clamping the disc in place. Only the lower spindle is motorized. Trays in half height drives often fully open and close using a motorized mechanism that can be pushed to close, controlled by the computer, or controlled using a button on the drive. Trays on half height and slim drives can also be locked by whatever program is using it, however it can still be ejected by inserting the end of a paper clip into an emergency eject hole on the front of the drive. Early CD players such as the Sony CDP-101 used a separate motorized mechanism to clamp the disc to the motorized spindle.
Slim drives use a special spindle with spring loaded specially shaped studs that radiate outwards, pressing against the inner edge of the disc. The user has to put uniform pressure onto the inner circumference of the disc to clamp it to the spindle and pull from the outer circumference while placing the thumb on the spindle to remove the disc, flexing it slightly in the process and returning to its normal shape after removal. The outer rim of the spindle may have a texturized silicone surface to exert friction keeping the disc from slipping. In slim drives most if not all components are on the disc tray, which pops out using a spring mechanism that can be controlled by the computer. These trays cannot close on their own; they have to be pushed until the tray reaches a stop.
Laser and optics
Optical pickup system
![Detail of DVD-RW optics](https://upload.wikimedia.org/wikipedia/commons/1/10/Detail_of_DVD-RW_optics.png)
The most important part of an optical disc drive is an ''optical path'', which is inside a ''pickup head'' (''PUH''). The PUH is also known as a laser pickup, optical pickup, pickup, pickup assembly, laser assembly, laser optical assembly, optical pickup head/unit or optical assembly.
It usually consists of a semiconductor
laser diode
The laser diode chip removed and placed on the eye of a needle for scale
A laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with e ...
, a
lens
A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements ...
for focusing the laser beam, and
photodiodes for detecting the light reflected from the disc's surface.
Initially, CD-type lasers with a
wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, t ...
of 780 nm (within the infrared) were used. For DVDs, the wavelength was reduced to 650 nm (red color), and for Blu-ray Disc this was reduced even further to 405 nm (violet color).
Two main
servomechanisms are used, the first to maintain the proper distance between lens and disc, to ensure the laser beam is focused as a small ''laser spot'' on the disc. The second servo moves the pickup head along the disc's radius, keeping the beam on the ''track'', a continuous spiral data path. Optical disc media are 'read' beginning at the inner radius to the outer edge.
Near the laser lens, optical drives are usually equipped with one to three tiny
potentiometer
A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat.
The measuring instrum ...
s (usually separate ones for
CDs,
DVD
The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kind ...
s, and usually a third one for
Blu-ray Discs if supported by the drive) that can be turned using a fine screwdriver. The potentiometer is in a
series circuit
Two-terminal components and electrical networks can be connected in series or parallel. The resulting electrical network will have two terminals, and itself can participate in a series or parallel topology. Whether a two-terminal "object" is a ...
with the laser lens and can be used to manually increase and decrease the laser power for
repair
The technical meaning of maintenance involves functional checks, servicing, repairing or replacing of necessary devices, equipment, machinery, building infrastructure, and supporting utilities in industrial, business, and residential installa ...
purposes.
[Video]
''PS2 Potentiometer Adjustment - Disk Read Error Fix - YouTube''
(2015-06-06)
The laser diode used in DVD writers can have powers of up to 100
milliwatt
The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Wat ...
s, such high powers are used during writing. Some CD players have
automatic gain control (AGC) to vary the power of the laser to ensure reliable playback of CD-RW discs.
Readability (the ability to read physically damaged or soiled discs) may vary among optical drives due to differences in optical pickup systems, firmwares, and damage patterns.
Read-only media
![Optical Disk Drive Photodetector](https://upload.wikimedia.org/wikipedia/commons/4/4a/Optical_Disk_Drive_Photodetector.jpg)
On factory-pressed ''read only media'' (ROM), during the manufacturing process the tracks are formed by pressing a thermoplastic resin into a nickel stamper that was made by plating a glass 'master' with raised 'bumps' on a flat surface, thus creating ''pits'' and ''lands'' in the plastic disk. Because the depth of the pits is approximately one-quarter to one-sixth of the laser's wavelength, the reflected beam's phase is shifted in relation to the incoming beam, causing mutual destructive
interference
Interference is the act of interfering, invading, or poaching. Interference may also refer to:
Communications
* Interference (communication), anything which alters, modifies, or disrupts a message
* Adjacent-channel interference, caused by extr ...
and reducing the reflected beam's intensity. This is detected by photodiodes that create corresponding electrical signals.
Recordable media
An optical disk recorder encodes (also known as burning, since the dye layer is permanently burned) data onto a recordable
CD-R
CD-R (Compact disc-recordable) is a digital optical disc storage format. A CD-R disc is a compact disc that can be written once and read arbitrarily many times.
CD-R discs (CD-Rs) are readable by most CD readers manufactured prior to the i ...
,
DVD-R,
DVD+R, or
BD-R disc (called a ''blank'') by selectively heating (burning) parts of an organic
dye layer with a laser.
This changes the reflectivity of the dye, thereby creating marks that can be read like the pits and lands on pressed discs. For recordable discs, the process is permanent and the media can be written to only once. While the reading laser is usually not stronger than 5
mW, the writing laser is considerably more powerful. DVD lasers operate at voltages of around 2.5 volts.
The higher the writing speed, the less time a laser has to heat a point on the media, thus its power has to increase proportionally. DVD burners' lasers often peak at about 200 mW, either in continuous wave and pulses, although some have been driven up to 400 mW before the diode fails.
Rewriteable media
For rewritable
CD-RW
CD-RW (Compact Disc-Rewritable) is a digital optical disc storage format introduced in 1997. A CD-RW compact disc (CD-RWs) can be written, read, erased, and re-written.
CD-RWs, as opposed to CDs, require specialized readers that have sensi ...
,
DVD-RW
DVD recordable and DVD rewritable are optical disc recording technologies. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only 'rewritable' discs are able to erase and rewrite data. Data is written ('bur ...
,
DVD+RW
DVD recordable and DVD rewritable are optical disc recording technologies. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only 'rewritable' discs are able to erase and rewrite data. Data is written ('burn ...
,
DVD-RAM
DVD-RAM (DVD Random Access Memory) is a DVD-based disc specification presented in 1996 by the DVD Forum, which specifies rewritable DVD-RAM media and the appropriate DVD writers. DVD-RAM media have been used in computers as well as camcorders ...
, or
BD-RE media, the laser is used to melt a
crystal
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macro ...
line metal
alloy
An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductilit ...
in the recording layer of the disc. Depending on the amount of power applied, the substance may be allowed to melt back (change the phase back) into crystalline form or left in an
amorphous form, enabling marks of varying reflectivity to be created.
Double-sided media
''Double-sided'' media may be used, but they are not easily accessed with a standard drive, as they must be physically turned over to access the data on the other side.
Dual layer media
''Double layer'' or ''dual layer'' (DL) media have two independent data layers separated by a semi-reflective layer. Both layers are accessible from the same side, but require the optics to change the laser's focus. Traditional ''single layer'' (SL) writable media are produced with a spiral groove molded in the protective
polycarbonate layer (not in the data recording layer), to lead and synchronize the speed of recording head. Double-layered writable media have: a first polycarbonate layer with a (shallow) groove, a first data layer, a semi-reflective layer, a second (spacer) polycarbonate layer with another (deep) groove, and a second data layer. The first groove spiral usually starts on the inner edge and extends outwards, while the second groove start on the outer edge and extends inwards.
Photothermal printing
Some drives support
Hewlett-Packard's
LightScribe
LightScribe is an optical disc recording technology that was created by the Hewlett-Packard Company. It uses specially coated recordable CD and DVD media to produce laser-etched labels with text or graphics, as opposed to stick-on labels and print ...
, or the alternative
LabelFlash photothermal printing Photothermal therapy (PTT) refers to efforts to use electromagnetic radiation (most often in infrared wavelengths) for the treatment of various medical conditions, including cancer. This approach is an extension of photodynamic therapy, in which a p ...
technology for labeling specially coated discs.
Multi beam drives
Zen Technology and Sony have developed drives that use several laser beams simultaneously to read discs and write to them at higher speeds than what would be possible with a single laser beam. The limitation with a single laser beam comes from wobbling of the disc that may occur at high rotational speeds; at 25,000 RPMs CDs become unreadable
while Blu-rays cannot be written to beyond 5,000 RPMs. With a single laser beam, the only way to increase read and write speeds without reducing the pit length of the disc (which would allow for more pits and thus bits of data per revolution, but may require smaller wavelength light) is by increasing the rotational speed of the disc which reads more pits in less time, increasing data rate; hence why faster drives spin the disc at higher speeds. In addition, CDs at 27,500 RPMs (such as to read the inside of a CD at 52x) may explode causing extensive damage to the disc's surroundings, and poor quality or damaged discs may explode at lower speeds.
In Zen's system (developed in conjunction with Sanyo and licensed by Kenwood), a diffraction grating is used to split a laser beam into 7 beams, which are then focused into the disc; a central beam is used for focusing and tracking the groove of the disc leaving 6 remaining beams (3 on either side) that are spaced evenly to read 6 separate portions of the groove of the disc in parallel, effectively increasing read speeds at lower RPMs, reducing drive noise and
stress on the disc. The beams then reflect back from the disc, and are collimated and projected into a special photodiode array to be read. The first drives using the technology could read at 40x, later increasing to 52x and finally 72x. It uses a single optical pickup.
In Sony's system (used on their proprietary Optical Disc Archive system which is based on
Archival Disc, itself based on Blu-ray) the drive has 4 optical pickups, two on each side of the disc, with each pickup having two lenses for a total of 8 lenses and laser beams. This allows for both sides of the disc to be read and written to at the same time, and for the contents of the disc to be verified during writing.
Rotational mechanism
File:Comparison disk storage.svg, Comparison of several forms of disk storage showing tracks (not-to-scale); green denotes start and red denotes end.
* Some CD-R(W) and DVD-R(W)/DVD+R(W) recorders operate in ZCLV, CAA or CAV modes.
File:CDRom.png, A half-height
A drive bay is a standard-sized area for adding hardware to a computer. Most drive bays are fixed to the inside of a case, but some can be removed.
Over the years since the introduction of the IBM PC, it and its compatibles have had many form ...
CD-ROM drive (without case)
The rotational mechanism in an optical drive differs considerably from that of a hard disk drive's, in that the latter keeps a
constant angular velocity
In optical storage, constant angular velocity (CAV) is a qualifier for the rated speed of any disc containing information, and may also be applied to the writing speed of recordable discs. A drive or disc operating in CAV mode maintains a cons ...
(CAV), in other words a constant number of
revolutions per minute
Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines.
Standards
ISO 80000-3:2019 defines a unit of rotation as the dimension ...
(RPM). With CAV, a higher
throughput
Network throughput (or just throughput, when in context) refers to the rate of message delivery over a communication channel, such as Ethernet or packet radio, in a communication network. The data that these messages contain may be delivered ove ...
is generally achievable at the outer disc compared to the inner.
On the other hand, optical drives were developed with an assumption of achieving a constant throughput, in CD drives initially equal to 150
KiB
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...
/s. It was a feature important for streaming audio data that always tend to require a constant
bit rate. But to ensure no disc capacity was wasted, a head had to transfer data at a maximum linear rate at all times too, without slowing on the outer rim of the disc. This led to optical drives—until recently—operating with a
constant linear velocity
In optical storage, constant linear velocity (CLV) is a qualifier for the rated speed of an optical disc drive, and may also be applied to the writing speed of recordable discs. CLV implies that the angular velocity (i.e. rpm) varies during an ...
(CLV). The spiral ''groove'' of the disc passed under its head at a constant speed. The implication of CLV, as opposed to CAV, is that disc angular velocity is no longer constant, and the spindle motor needed to be designed to vary its speed from between 200 RPM on the outer rim and 500 RPM on the inner, keeping the data rate constant.
Later CD drives kept the CLV paradigm, but evolved to achieve higher rotational speeds, popularly described in multiples of a base speed. As a result, a 4× CLV drive, for instance, would rotate at 800-2000 RPM, while transferring data steadily at 600 KiB/s, which is equal to 4 × 150 KiB/s.
For DVDs, base or 1× speed is 1.385 MB/s, equal to 1.32 MiB/s, approximately nine times faster than the CD base speed. For Blu-ray drives, base speed is 6.74 MB/s, equal to 6.43 MiB/s.
![Zone clv](https://upload.wikimedia.org/wikipedia/commons/6/6a/Zone_clv.jpg)
Because keeping a constant transfer rate for the whole disc is not so important in most contemporary CD uses, a pure CLV approach had to be abandoned to keep the rotational speed of the disc safely low while maximizing data rate. Some drives work in a partial CLV (PCLV) scheme, by switching from CLV to CAV only when a rotational limit is reached. But switching to CAV requires considerable changes in hardware design, so instead most drives use the
zoned constant linear velocity
In optical storage, constant linear velocity (CLV) is a qualifier for the rated speed of an optical disc drive, and may also be applied to the writing speed of recordable discs. CLV implies that the angular velocity (i.e. rpm) varies during an ...
(Z-CLV) scheme. This divides the disc into several zones, each having its own constant linear velocity. A Z-CLV recorder rated at "52×", for example, would write at 20× on the innermost zone and then progressively increase the speed in several discrete steps up to 52× at the outer rim. Without higher rotational speeds, increased read performance may be attainable by simultaneously reading more than one point of a data groove, also known as ''multi-beam'',
but drives with such mechanisms are more expensive, less compatible, and very uncommon.
Limit
Both DVDs and CDs have been known to explode
when damaged or spun at excessive
speeds. This imposes a constraint on the maximum safe speeds (56×
CAV for CDs or around 18×CAV in the case of DVDs) at which drives can operate.
The reading speeds of most
half-height
A drive bay is a standard-sized area for adding hardware to a computer. Most drive bays are fixed to the inside of a case, but some can be removed.
Over the years since the introduction of the IBM PC, it and its compatibles have had many form ...
optical disc drives released since circa 2007 are limited to ×48 for CDs, ×16 for DVDs and ×12 (
angular velocities) for Blu-ray Discs. Writing speeds on selected
write-once media are higher.
Some optical drives additionally throttle the reading speed based on the contents of optical discs, such as max. 40× CAV (constant angular velocity) for the
Digital Audio Extraction (''“DAE”'') of
Audio CD
Compact Disc Digital Audio (CDDA or CD-DA), also known as Digital Audio Compact Disc or simply as Audio CD, is the standard format for audio compact discs. The standard is defined in the ''Red Book'', one of a series of Rainbow Books (named ...
tracks,
16× CAV for
Video CD
Video CD (abbreviated as VCD, and also known as Compact Disc Digital Video) is a home video format and the first format for distributing films on standard optical discs. The format was widely adopted in Southeast Asia, Central Asia and the ...
contents
and even lower limitations on earlier models such as 4× CLV (
constant linear velocity
In optical storage, constant linear velocity (CLV) is a qualifier for the rated speed of an optical disc drive, and may also be applied to the writing speed of recordable discs. CLV implies that the angular velocity (i.e. rpm) varies during an ...
) for
Video CD
Video CD (abbreviated as VCD, and also known as Compact Disc Digital Video) is a home video format and the first format for distributing films on standard optical discs. The format was widely adopted in Southeast Asia, Central Asia and the ...
s.
[Pioneer DVR-A06 brochure]
(2003)
Loading mechanisms
Tray and slot loading
Current optical drives use either a ''tray-loading'' mechanism, where the disc is loaded onto a motorized (as utilized by
half-height
A drive bay is a standard-sized area for adding hardware to a computer. Most drive bays are fixed to the inside of a case, but some can be removed.
Over the years since the introduction of the IBM PC, it and its compatibles have had many form ...
, ''"desktop"'' drives) tray, a manually operated tray (as utilized in
laptop computers, also called ''slim type''), or a ''slot-loading'' mechanism, where the disc is slid into a slot and drawn in by motorized rollers. Slot-loading optical drives exist in both half-height (desktop) and slim type (laptop) form factors.
[Pioneer computer drive archive]
/ref>
With both types of mechanisms, if a CD or DVD is left in the drive after the computer is turned off, the disc cannot be ejected using the normal eject mechanism of the drive. However, tray-loading drives account for this situation by providing a small hole where one can insert a paperclip to manually open the drive tray to retrieve the disc.
Slot-loading optical disc drives are prominently used in game consoles and vehicle audio
Vehicle audio is equipment installed in a car or other vehicle to provide in-car entertainment and information for the vehicle occupants. Until the 1950s it consisted of a simple AM radio. Additions since then have included FM radio (1952), 8 ...
units. Although allowing more convenient insertion, those have the disadvantages that they cannot usually accept the smaller 80 mm diameter discs (unless 80 mm optical disc adapter is used) or any non-standard sizes, usually have no emergency eject hole or eject button, and therefore have to be disassembled if the optical disc cannot be ejected normally. However, some slot-loading optical drives have been engineered to support miniature discs. The Nintendo Wii
The Wii ( ) is a home video game console developed and marketed by Nintendo. It was released on November 19, 2006, in North America and in December 2006 for most other regions of the world. It is Nintendo's fifth major home game console, f ...
, because of backward compatibility
Backward compatibility (sometimes known as backwards compatibility) is a property of an operating system, product, or technology that allows for interoperability with an older legacy system, or with input designed for such a system, especiall ...
with Nintendo GameCube
The is a home video game console developed and released by Nintendo in Japan on September 14, 2001, in North America on November 18, 2001, and in PAL territories in 2002. It is the successor to the Nintendo 64 (1996), and predecessor of the Wii ...
games, and PlayStation 3
The PlayStation 3 (PS3) is a home video game console developed by Sony Computer Entertainment. The successor to the PlayStation 2, it is part of the PlayStation brand of consoles. It was first released on November 11, 2006, in Japan, November ...
video game consoles are able to load both standard size DVDs and 80 mm discs in the same slot-loading drive. Its successor's slot drive however, the Wii U
The Wii U ( ) is a home video game console developed by Nintendo as the successor to the Wii. Released in late 2012, it is the first eighth-generation video game console and competed with Microsoft's Xbox One and Sony's PlayStation 4.
Th ...
, lacks miniature disc compatibility.
There were also some early CD-ROM drives for desktop PCs in which its tray-loading mechanism will eject slightly and user has to pull out the tray manually to load a CD, similar to the tray ejecting method used in internal optical disc drives of modern laptops and modern external slim portable optical disc drives. Like the top-loading mechanism, they have spring-loaded ball bearings on the spindle.
Top-load
A small number of drive models, mostly compact portable units, have a ''top-loading'' mechanism where the drive lid is manually opened upwards and the disc is placed directly onto the spindle[LiteOn eTAU108 - DVD±RW (±R DL) / DVD-RAM drive - Hi-Speed USB Series Specification sheet and picture]
- CNet.com, 2009; accessed July 11th 2020. (for example, all PlayStation One consoles, PlayStation 2 Slim, PlayStation 3 Super Slim, Nintendo GameCube consoles, Nintendo Wii Mini, most portable CD player
A portable CD player is a portable audio player used to play compact discs. The first audio player released was the Discman D-50 by Sony.Lungu, R"History of the Portable Audio Player." 2008-11-27.
Features
The basic features of a portable CD ...
s, and some standalone CD recorders feature top-loading drives). These sometimes have the advantage of using spring-loaded ball bearings to hold the disc in place, minimizing damage to the disc if the drive is moved while it is spun up.
Unlike tray and slot loading mechanisms by default, top-load optical drives can be opened without being connected to power.
Cartridge load
Some early CD-ROM drives used a mechanism where CDs had to be inserted into special cartridges or caddies
In golf, a caddie (or caddy) is the person who carries a player's bag and clubs, and gives the player advice and moral support.
Description
A good caddie is aware of the challenges and obstacles of the golf course being played, along with the ...
, somewhat similar in appearance to a 3.5 inch micro floppy diskette. This was intended to protect the disc from accidental damage by enclosing it in a tougher plastic casing, but did not gain wide acceptance due to the additional cost and compatibility concerns—such drives would also inconveniently require "bare" discs to be manually inserted into an openable caddy before use. Ultra Density Optical
Ultra Density Optical (UDO) is an optical disc format designed for high-density storage of high-definition video and data.
Overview
An Ultra Density Optical disc, or UDO, is a 133.35 mm (5.25") ISO cartridge optical disc which can store up ...
(''UDO''), Magneto-optical drive
A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon a magneto-optical disc. Both 130 mm (5.25 in) and 90 mm (3.5 in) form factors exist. In 1983, just a year after the introduct ...
s, Universal Media Disc
The Universal Media Disc (UMD) is a discontinued optical disc medium developed by Sony for use on its PlayStation Portable handheld gaming and multimedia platform. It can hold up to 1.8 gigabytes of data and is capable of storing video games, f ...
(''UMD''), DataPlay, Professional Disc
Professional Disc (PFD) is a digital recording optical disc format introduced by Sony in 2003 primarily for XDCAM, its tapeless camcorder system. It was one of the first optical formats to utilize a blue laser, which allowed for a higher densi ...
, MiniDisc, Optical Disc Archive as well as early DVD-RAM
DVD-RAM (DVD Random Access Memory) is a DVD-based disc specification presented in 1996 by the DVD Forum, which specifies rewritable DVD-RAM media and the appropriate DVD writers. DVD-RAM media have been used in computers as well as camcorders ...
and Blu-ray
The Blu-ray Disc (BD), often known simply as Blu-ray, is a digital optical disc data storage format. It was invented and developed in 2005 and released on June 20, 2006 worldwide. It is designed to supersede the DVD format, and capable of st ...
discs use optical disc cartridges.
Computer interfaces
All optical disc-drives use the SCSI-protocol on a command bus level, and initial systems used either a fully featured SCSI bus
A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...
or as these were some what cost-prohibitive to sell to consumer applications, a proprietary cost-reduced version of the bus. This is because conventional ATA-standards at the time did not support, or have any provisions for any sort of removable media or hot-plugging of disk drives. Most modern internal drives for personal computer
A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...
s, server
Server may refer to:
Computing
*Server (computing), a computer program or a device that provides functionality for other programs or devices, called clients
Role
* Waiting staff, those who work at a restaurant or a bar attending customers and su ...
s, and workstation
A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating systems. The term ''workstat ...
s are designed to fit in a standard -inch (also written as 5.25 inch) drive bay
A drive bay is a standard-sized area for adding hardware to a computer. Most drive bays are fixed to the inside of a case, but some can be removed.
Over the years since the introduction of the IBM PC, it and its compatibles have had many form ...
and connect to their host via an ATA or SATA
SATA (Serial AT Attachment) is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, and solid-state drives. Serial ATA succeeded the earlier Parallel ATA (PATA) standard t ...
bus interface, but communicate using the SCSI protocol commands on software level as per the ATA Package Interface standard developed for making Parallel ATA/IDE interfaces compatible with removable media. Some devices may support vendor-specific commands such as recording density ("GigaRec
CD-R (Compact disc-recordable) is a digital optical disc storage format. A CD-R disc is a compact disc that can be written once and read arbitrarily many times.
CD-R discs (CD-Rs) are readable by most CD readers manufactured prior to the in ...
"), laser power setting (" VariRec"), ability to manually hard-limit rotation speed in a way that overrides the universal speed setting (separately for reading and writing), and adjusting the lens and tray movement speeds where a lower setting reduces noise
Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference aris ...
, as implmenented on some Plextor
Plextor (styled PLEXTOR) ( zh, 浦科特; ja, プレクスター) is a Taiwanese (formerly Japanese) consumer electronics brand, best known for solid-state drives and optical disc drives.
Company
The brand name Plextor was used for all products ...
drives, as well as the ability to force overspeed burning, meaning beyond speed recommended for the media type, for testing purposes, as implemented on some Lite-On
Lite-On (also known as LiteOn and LiteON) is a Taiwanese company that primarily manufactures consumer electronics, including LEDs, semiconductors, computer chassis, monitors, motherboards, optical disc drives, and other electronic components ...
drives. Additionally, there may be digital and analog outputs for audio. The outputs may be connected via a header cable to the sound card or the motherboard or to headphones or an external speaker with a 3.5mm AUX plug cable that many early optical drives are equipped with. At one time, computer software resembling CD player
A CD player is an electronic device that plays audio compact discs, which are a digital optical disc data storage format. CD players were first sold to consumers in 1982. CDs typically contain recordings of audio material such as music or audio ...
s controlled playback of the CD. Today the information is extracted from the disc as digital data, to be played back or converted to other file formats.
Some early optical drives have dedicated buttons for CD playback controls on their front panel, allowing them to act as a standalone compact disc player
A CD player is an electronic device that plays audio compact discs, which are a digital optical disc data storage format. CD players were first sold to consumers in 1982. CDs typically contain recordings of audio material such as music or aud ...
.
External drives were popular in the beginning, because the drives often required complex electronics to institute, rivaling in complexity the Host computer system itself. External drives using SCSI, Parallel port, USB
Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
and FireWire interfaces exist, most modern drives being USB
Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
. Some portable versions for laptops power themselves from batteries or directly from their interface bus.
Drives with a SCSI interface were originally the only system interface available, but they never became popular in the price sensitive low-end consumer market which constituted majority of the demand. They were less common and tended to be more expensive, because of the cost of their interface chipsets, more complex SCSI connectors, and small volume of sales in comparison to proprietary cost-reduced applications, but most importantly because most consumer market computer systems did not have any sort of SCSI interface in them the market for them was small. However, support for multitude of various cost-reduced proprietary optical drive bus standards were usually embedded with sound cards which were often bundled with the optical drives themselves in the early years. Some sound card and optical drive bundles even featured a full SCSI bus. Modern IDE/ATAPI compliant Parallel ATA and Serial ATA drive control chipsets and their interface technology is more complex to manufacture than a traditional 8bit 50Mhz SCSI drive interface, because they feature properties of both the SCSI and ATA bus, but are cheaper to make overall due to economies of scale.
When the optical disc drive was first developed, it was not easy to add to computer systems. Some computers such as the IBM PS/2 were standardizing on the -inch floppy and -inch hard disk and did not include a place for a large internal device. Also IBM PCs and clones at first only included a single (parallel) ATA drive interface, which by the time the CD-ROM was introduced, was already being used to support two hard drives and were completely incapable of supporting removable media, a drive falling off or being removed from the bus while the system was live, would cause an unrecoverable error and crash the entire system. Early consumer grade laptops simply had no built-in high-speed interface for supporting an external storage device. High-end workstation systems and laptops featured a SCSI interface which had a standard for externally connected devices.
This was solved through several techniques:
* Early sound cards
A sound card (also known as an audio card) is an internal expansion card that provides input and output of audio signals to and from a computer under the control of computer programs. The term ''sound card'' is also applied to external audio ...
could include a CD-ROM drive interface. Initially, such interfaces were proprietary to each CD-ROM manufacturer. A sound card could often have two or three different interfaces which are able to communicate with the CD-ROM drive.
* A method for using the parallel port to use with external drives was developed at some point. This interface was traditionally used to connect a printer, but despite popular myth it is not its only use and various different external auxiliary devices exist for the IEEE-1278 bus, including but not limited to tape backup drives etc. This was slow but an option for low-to-midrange laptops without integrated or PCMCIA extension bus connected SCSI.
* A PCMCIA optical drive interface was also developed for laptops.
* A SCSI card could be installed in desktop PCs to cater for an external SCSI drive enclosure or to run internally mounted SCSI Hard disk drives and optical drives, though SCSI was typically somewhat more expensive than other options, with some OEMs charging a premium for it.
Due to lack of asynchrony in existing implementations, an optical drive encountering damaged sectors may cause computer programs trying to access the drives, such as Windows Explorer
File Explorer, previously known as Windows Explorer, is a file manager application that is included with releases of the Microsoft Windows operating system from Windows 95 onwards. It provides a graphical user interface for accessing the file ...
, to lock up.
SCSI configuration
Drive models may support adjustment of behavioural parameters for performance optimization and testing purposes, such as the read retry count (RRC
), write retry count (WRC
), and the option to deactivate error correction (DCR
). For example, the read retry count specifies how often the drive should attempt reading a damaged sector. A higher value may increase the chance of successfully reading individual damaged sectors, but at the expense of responsiveness, since it adds delays during which the device seems unresponsive to the computer.
The sdparm
command-line utility allows manually controlling such parameters. For example, sdparm --set RRC=10 /dev/sr0
sets the read retry count to 10 for the optical drive device file
In Unix-like operating systems, a device file or special file is an interface to a device driver that appears in a file system as if it were an ordinary file. There are also special files in DOS, OS/2, and Windows. These special files allow a ...
"sr0", and sdparm --all /dev/sr0
lists all code pages. The values may be interpreted varyingly among drive models or vendors.
Internal mechanism of a drive
The optical drives in the photos are shown right side up; the disc would sit on top of them. The laser and optical system scans the underside of the disc.
With reference to the top photo, just to the right of image center is the disc motor, a metal cylinder, with a gray centering hub and black rubber drive ring on top. There is a disc-shaped round clamp, loosely held inside the cover and free to rotate; it's not in the photo. After the disc tray stops moving inward, as the motor and its attached parts rise, a magnet near the top of the rotating assembly contacts and strongly attracts the clamp to hold and center the disc. This motor is an "outrunner"-style brushless DC motor which has an external rotor – every visible part of it spins.
Two parallel guide rods that run between upper left and lower right in the photo carry the "sled
A sled, skid, sledge, or sleigh is a land vehicle that slides across a surface, usually of ice or snow. It is built with either a smooth underside or a separate body supported by two or more smooth, relatively narrow, longitudinal runners ...
", the moving optical read-write head. As shown, this "sled" is close to, or at the position where it reads or writes at the edge of the disc. To move the "sled" during continuous read or write operations, a stepper motor
A stepper motor, also known as step motor or stepping motor, is a brushless DC electric motor that divides a full rotation into a number of equal steps. The motor's position can be commanded to move and hold at one of these steps without any posi ...
rotates a leadscrew to move the "sled" throughout its total travel range. The motor, itself, is the short gray cylinder just to the left of the most-distant shock mount; its shaft is parallel to the support rods. The leadscrew is the rod with evenly-spaced darker details; these are the helical grooves that engage a pin on the "sled".
In contrast, the mechanism shown in the second photo, which comes from a cheaply made DVD player, uses less accurate and less efficient brushed DC motors to both move the sled and spin the disc. Some older drives use a DC motor to move the sled, but also have a magnetic rotary encoder
A rotary encoder, also called a shaft encoder, is an electro-mechanical device that converts the angular position or motion of a shaft or axle to analog or digital output signals.
There are two main types of rotary encoder: absolute and increm ...
to keep track of the position. Most drives in computers use stepper motors.
The gray metal chassis is shock-mounted at its four corners to reduce sensitivity to external shocks, and to reduce drive noise from residual imbalance when running fast. The soft shock mount grommets are just below the brass-colored screws at the four corners (the left one is obscured).
In the third photo, the components under the cover of the lens mechanism are visible. The two permanent magnets on either side of the lens holder as well as the coils that move the lens can be seen. This allows the lens to be moved up, down, forwards, and backwards to stabilize the focus of the beam.
In the fourth photo, the inside of the optics package can be seen. Note that since this is a CD-ROM drive, there is only one laser, which is the black component mounted to the bottom left of the assembly. Just above the laser are the first focusing lens and prism that direct the beam at the disc. The tall, thin object in the center is a half-silvered mirror
A mirror or looking glass is an object that reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the direction of the im ...
that splits the laser beam in multiple directions. To the bottom right of the mirror is the main photodiode that senses the beam reflected off the disc. Above the main photodiode is a second photodiode that is used to sense and regulate the power of the laser.
The irregular orange material is flexible etched copper foil supported by thin sheet plastic; these are " flexible circuits" that connect everything to the electronics (which is not shown).
History
The first laser disc, demonstrated in 1972, was the ''Laservision'' 12-inch video disc. The video signal was stored as an analog format like a video cassette. The first digitally recorded optical disc was a 5-inch audio compact disc
The compact disc (CD) is a digital optical disc data storage format that was co-developed by Philips and Sony to store and play digital audio recordings. In August 1982, the first compact disc was manufactured. It was then released in Oc ...
(CD) in a read-only format created by Sony
, commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professiona ...
and Philips in 1975.
The first erasable optical disc drives were announced in 1983, by Matsushita (Panasonic),[''Lasers & Optronics'', Volume 6](_blank)
page 77 Sony, and Kokusai Denshin Denwa (KDDI). Sony eventually released the first commercial erasable and rewritable -inch optical disc drive in 1987, with dual-sided discs capable of holding 325 MB per side.
The CD-ROM format was developed by Sony and Denon, introduced in 1984, as an extension of Compact Disc Digital Audio
Compact Disc Digital Audio (CDDA or CD-DA), also known as Digital Audio Compact Disc or simply as Audio CD, is the standard format for audio compact discs. The standard is defined in the ''Red Book'', one of a series of Rainbow Books (named ...
and adapted to hold any form of digital data. The CD-ROM format has a storage capacity of 650 MB. Also in 1984, Sony introduced a LaserDisc data storage format, with a larger data capacity of 3.28 GB.
In September 1992, Sony announced the MiniDisc format, which was supposed to combine the audio clarity of CD's and the convenience of a cassette size. The standard capacity holds 80 minutes of audio. In January 2004, Sony revealed an upgraded Hi-MD
Hi-MD is a magneto-optical disc-based data storage format. It was a further development of the MiniDisc. With its release in later 2004, format, which increased the capacity to 1 GB (48 hours of audio).
The DVD
The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kind ...
format, developed by Panasonic
formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational conglomerate corporation, headquartered in Kadoma, Osaka. It was founded by Kōnosuke Matsushita in 1918 as a lightbulb ...
, Sony, and Toshiba
, commonly known as Toshiba and stylized as TOSHIBA, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. Its diversified products and services include power, industrial and social infrastructure systems, ...
, was released in 1995, and was capable of holding 4.7 GB per layer; with the first DVD players shipping on November 1, 1996, by Panasonic and Toshiba in Japan and the first DVD-ROM compatible computers being shipped on November 6 of that year by Fujitsu. Sales of DVD-ROM drives for computers in the U.S. began on March 24, 1997, when Creative Labs
Creative Technology Ltd. is a Singaporean multinational technology company headquartered with overseas offices in Shanghai, Tokyo, Dublin, and Silicon Valley (where in the US it is known as Creative Labs). The principal activities of the compa ...
released their PC-DVD kit to the market.
In 1999, Kenwood released a multi-beam optical drive that achieved burning speeds as high as 72×, which would require dangerous spinning speeds to attain with single-beam burning. However, it suffered from reliability issues.
The first Blu-ray
The Blu-ray Disc (BD), often known simply as Blu-ray, is a digital optical disc data storage format. It was invented and developed in 2005 and released on June 20, 2006 worldwide. It is designed to supersede the DVD format, and capable of st ...
prototype was unveiled by Sony
, commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professiona ...
in October 2000, and the first commercial recording device was released to market on April 10, 2003. In January 2005, TDK
is a Japanese multinational electronics corporation that manufactures electronic components and recording and data-storage media. Its motto is "Contribute to culture and industry through creativity".
"TDK" is an initialism of the original Ja ...
announced that they had developed an ultra-hard yet very thin polymer coating ("Durabis
Durabis (Latin for "you will last") is a brand name for a clear polymer coating developed by the TDK Corporation. It was unveiled at CES 2005 to remove the need for "cumbersome" protective cartridges to protect the media’s recording layer. The ...
") for Blu-ray Discs; this was a significant technical advance because better protection was desired for the consumer market to protect bare discs against scratching and damage compared to DVD. Technically Blu-ray Disc also required a thinner layer for the narrower beam and shorter wavelength 'blue' laser. The first BD-ROM players (Samsung
The Samsung Group (or simply Samsung) ( ko, 삼성 ) is a South Korean multinational manufacturing conglomerate headquartered in Samsung Town, Seoul, South Korea. It comprises numerous affiliated businesses, most of them united under the ...
BD-P1000) were shipped in mid-June 2006. The first Blu-ray Disc titles were released by Sony
, commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professiona ...
and MGM
Metro-Goldwyn-Mayer Studios Inc., also known as Metro-Goldwyn-Mayer Pictures and abbreviated as MGM, is an American film, television production, distribution and media company owned by Amazon through MGM Holdings, founded on April 17, 1924 a ...
on June 20, 2006. The first mass-market Blu-ray Disc rewritable drive for the PC was the BWU-100A, released by Sony
, commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professiona ...
on July 18, 2006.
Starting in the mid 2010s, computer manufacturers began to stop including built-in optical disc drives on their products, with the advent of cheap, rugged (scratches can not cause corrupted data, inaccessible files or skipping audio/video), fast and high capacity USB drives and video on demand over the internet. Excluding an optical drive allows for circuit boards in laptops to be larger and less dense, requiring less layers, reducing production costs while also reducing weight and thickness, or for batteries to be larger. Computer case manufacturers also began to stop including -inch bays for installing optical disc drives. However, new optical disc drives are still (as of 2020) available for purchase. Notable optical disc drive OEMs include Hitachi, LG Electronics
LG Electronics Inc. () is a South Korean multinational electronics company headquartered in Yeouido-dong, Seoul, South Korea. LG Electronics is a part of LG Corporation, the fourth largest '' chaebol'' in South Korea, and often considered a ...
(merged into Hitachi-LG Data Storage
Hitachi-LG Data Storage (HLDS, HL-DT-ST or H-L Data Storage), a joint venture between Hitachi and LG, is a manufacturer of DVD and Blu-ray
The Blu-ray Disc (BD), often known simply as Blu-ray, is a digital optical disc data storage form ...
), Toshiba
, commonly known as Toshiba and stylized as TOSHIBA, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. Its diversified products and services include power, industrial and social infrastructure systems, ...
, Samsung Electronics
Samsung Electronics Co., Ltd. (, sometimes shortened to SEC and stylized as SΛMSUNG) is a South Korean multinational electronics corporation headquartered in Yeongtong-gu, Suwon, South Korea. It is the pinnacle of the Samsung chaebol, a ...
(merged into Toshiba Samsung Storage Technology), Sony
, commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professiona ...
, NEC
is a Japanese multinational information technology and electronics corporation, headquartered in Minato, Tokyo. The company was known as the Nippon Electric Company, Limited, before rebranding in 1983 as NEC. It provides IT and network soluti ...
(merged into Optiarc
Optiarc is a brand of optical disc drives and solid-state drives. It is owned by a US-based Vinpower Digital, Inc.
Initially Optiarc was established on April 3, 2006 as a joint venture between Sony (55% shares) and NEC (45% shares). The compan ...
), Lite-On, Philips
Koninklijke Philips N.V. (), commonly shortened to Philips, is a Dutch multinational conglomerate corporation that was founded in Eindhoven in 1891. Since 1997, it has been mostly headquartered in Amsterdam, though the Benelux headquarters i ...
(merged into Philips & Lite-On Digital Solutions), Pioneer Corporation
commonly referred to as Pioneer, is a Japanese multinational corporation based in Tokyo, that specializes in digital entertainment products. The company was founded by Nozomu Matsumoto in January 1, 1938 in Tokyo as a radio and speaker repair ...
, Plextor
Plextor (styled PLEXTOR) ( zh, 浦科特; ja, プレクスター) is a Taiwanese (formerly Japanese) consumer electronics brand, best known for solid-state drives and optical disc drives.
Company
The brand name Plextor was used for all products ...
, Panasonic
formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational conglomerate corporation, headquartered in Kadoma, Osaka. It was founded by Kōnosuke Matsushita in 1918 as a lightbulb ...
, Yamaha Corporation
is a Japanese multinational corporation and conglomerate with a very wide range of products and services. It is one of the constituents of Nikkei 225 and is the world's largest musical instrument manufacturing company. The former motorcycle divi ...
and Kenwood.
Compatibility
Most optical drives are backward compatible with their ancestors up to CD, although this is not required by standards.
Compared to a CD's 1.2 mm layer of polycarbonate, a DVD's laser beam only has to penetrate 0.6 mm in order to reach the recording surface. This allows a DVD drive to focus the beam on a smaller spot size and to read smaller pits. DVD lens supports a different focus for CD or DVD media with same laser. With the newer Blu-ray Disc drives, the laser only has to penetrate 0.1 mm of material. Thus the optical assembly would normally have to have an even greater focus range. In practice, the Blu-ray optical system is separate from the DVD/CD system.
* Some types of CD-R media with less-reflective dyes may cause problems.
* May not work in non MultiRead-compliant drives.
* May not work in some early-model DVD-ROM drives. CD-R would not work in any drive that did not have a 780 nm laser. CD-RW compatibility varied.
* DVD+RW discs did not work in early video players that played DVD-RW discs. This was not due to any incompatibility with the format but was a deliberate feature built into the firmware by one drive manufacturer.
* Read compatibility with existing DVD drives may vary greatly with the brand of DVD+R DL media used. Also drives that predated the media did not have the book code for DVD+R DL media in their firmware (this was not an issue for DVD-R DL though some drives could only read the first layer).
* Early DVD+RW and DVD+R recorders could not write to DVD-R(W) media (and vice versa).
* Will work in all drives that read DVD-R as compatibility ID byte is the same.
* Recorder firmware may blacklist or otherwise refuse to record to some brands of DVD-RW media.
* DVD+RW format was released before DVD+R. All DVD+RW only drives could be upgraded to write DVD+R discs by a firmware upgrade.
* As of April 2005, all DVD+R DL recorders on the market are Super Multi-capable.
* As of October 2006, recently released BD drives are able to read and write CD media.
* Older CD player models might struggle with the low reflectivity of CD-RW media.
* Also known as ''"DVD Multi Recorder"''
Recording performance
During the times of CD writer drives, they are often marked with three different speed ratings. In these cases, the first speed is for write-once (R) operations, the second speed for re-write (RW) operations, and the last speed for read-only (ROM) operations. For example, a 40×/16×/48× CD writer drive is capable of writing to CD-R media at speed of 40× (6,000 kbit/s), writing to CD-RW media at speed of 16× (2,400 kbit/s), and reading from a CD-ROM media at speed of 48× (7,200 kbit/s).
During the times of combo (CD-RW/DVD-ROM) drives, an additional speed rating (e.g. the 16× in 52×/32×/52×/16×) is designated for DVD-ROM media reading operations.
For DVD writer drives, Blu-ray Disc combo drives, and Blu-ray Disc writer drives, the writing and reading speed of their respective optical media are specified in its retail box, user's manual, or bundled brochures or pamphlets.
In the late 1990s, ''buffer underruns'' became a very common problem as high-speed CD recorders began to appear in home and office computers, which—for a variety of reasons—often could not muster the I/O performance to keep the data stream to the recorder steadily fed. The recorder, should it run short, would be forced to halt the recording process, leaving a truncated track that usually renders the disc useless.
In response, manufacturers of CD recorders began shipping drives with "buffer underrun protection" (under various trade names, such as Sanyo
, stylized as SANYO, is a Japanese electronics company and formerly a member of the ''Fortune'' Global 500 whose headquarters was located in Moriguchi, Osaka prefecture, Japan. Sanyo had over 230 subsidiaries and affiliates, and was founded by ...
's "BURN-Proof", Ricoh
is a Japanese Multinational corporation, multinational imaging and electronics company (law), company. It was founded by the now-defunct commercial division of the Riken, Institute of Physical and Chemical Research (Riken) known as the ''Riken ...
's "JustLink" and Yamaha Yamaha may refer to:
* Yamaha Corporation, a Japanese company with a wide range of products and services, established in 1887. The company is the largest shareholder of Yamaha Motor Company (below).
** Yamaha Music Foundation, an organization estab ...
's "Lossless Link"). These can suspend and resume the recording process in such a way that the gap the stoppage produces can be dealt with by the error-correcting
In information theory and coding theory with applications in computer science and telecommunication, error detection and correction (EDAC) or error control are techniques that enable reliable delivery of digital data over unreliable commun ...
logic built into CD players and CD-ROM drives. The first of these drives were rated at 12× and 16×.
The first optical drive to support recording DVDs at 16× speed was the Pioneer
Pioneer commonly refers to a settler who migrates to previously uninhabited or sparsely inhabited land.
In the United States pioneer commonly refers to an American pioneer, a person in American history who migrated west to join in settling and de ...
DVR-108, released in the second half of 2004. At that time however, no recordable DVD media supported that high recording speed yet.[''"Pioneer DVR-108: 16x-DVD-Brenner im PC-WELT-Test"'']
(PCwelt.de, 2004-08-12) (German)][''"16fach-DVD-Brenner Pioneer DVR-108 Der schnellste DVD-Brenner"'']
− CHIP.DE (2004-10-16) (German)[Pioneer DVR-108 – Product information and specifications]
/ref>
While drives are burning DVD+R, DVD+RW and all Blu-ray formats, they do not require any such error correcting recovery as the recorder is able to place the new data exactly on the end of the suspended write effectively producing a continuous track (this is what the DVD+ technology achieved). Although later interfaces were able to stream data at the required speed, many drives now write in a 'zoned constant linear velocity
In optical storage, constant linear velocity (CLV) is a qualifier for the rated speed of an optical disc drive, and may also be applied to the writing speed of recordable discs. CLV implies that the angular velocity (i.e. rpm) varies during an ...
' (''"Z-CLV"''). This means that the drive has to temporarily suspend the write operation while it changes speed and then recommence it once the new speed is attained. This is handled in the same manner as a buffer underrun.
The internal buffer of optical disc writer drives is: 8 MiB or 4 MiB when recording BD-R, BD-R DL, BD-RE, or BD-RE DL media; 2 MiB when recording DVD-R, DVD-RW, DVD-R DL, DVD+R, DVD+RW, DVD+RW DL, DVD-RAM, CD-R, or CD-RW media.
Recording schemes
CD recording on personal computers was originally a batch-oriented task in that it required specialised optical disc authoring software, authoring software to create an " image" of the data to record and to record it to disc in the one session. This was acceptable for archival purposes, but limited the general convenience of CD-R and CD-RW discs as a removable storage medium.
Packet writing
Packet writing (or incremental packet writing, IPW) is an optical disc recording technology used to allow write-once and rewritable CD and DVD media to be used in a similar manner to a floppy disk from within the operating system.
Details
...
is a scheme in which the recorder writes incrementally to disc in short bursts, or packets. Sequential packet writing fills the disc with packets from bottom up. To make it readable in CD-ROM and DVD-ROM drives, the disc can be ''closed'' at any time by writing a final table-of-contents to the start of the disc; thereafter, the disc cannot be packet-written any further. Packet writing, together with support from the operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also i ...
and a file system like UDF, can be used to mimic random write-access as in media like flash memory and magnetic disks.
Fixed-length packet writing (on CD-RW and DVD-RW media) divides up the disc into padded, fixed-size packets. The padding reduces the capacity of the disc, but allows the recorder to start and stop recording on an individual packet without affecting its neighbours. These resemble the block-writable access offered by magnetic media closely enough that many conventional file systems will work as-is. Such discs, however, are not readable in most CD-ROM and DVD-ROM drives or on most operating systems without additional third-party drivers. The division into packets is not as reliable as it may seem as CD-R(W) and DVD-R(W) drives can only locate data to within a data block. Although generous gaps (the padding referred to above) are left between blocks, the drive nevertheless can occasionally miss and either destroy some existing data or even render the disc unreadable.
The DVD+RW disc format eliminates this unreliability by embedding more accurate timing hints in the data groove of the disc and allowing individual data blocks (or even bytes) to be replaced without affecting backward compatibility (a feature dubbed "lossless linking"). The format itself was designed to deal with discontinuous recording because it was expected to be widely used in digital video recorders. Many such DVRs use variable-rate video compression schemes which require them to record in short bursts; some allow simultaneous playback and recording by alternating quickly between recording to the tail of the disc whilst reading from elsewhere. The Blu-ray Disc system also encompasses this technology.
Mount Rainier aims to make packet-written CD-RW and DVD+RW discs as convenient to use as that of removable magnetic media by having the firmware format new discs in the background and manage media defects (by automatically mapping parts of the disc which have been worn out by erase cycles to reserve space elsewhere on the disc). As of February 2007, support for Mount Rainier is natively supported in Windows Vista
Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...
. All previous versions of Windows require a third-party solution, as does Mac OS X
macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and la ...
.
Recorder Unique Identifier
Owing to pressure from the music industry, as represented by the IFPI
The International Federation of the Phonographic Industry (IFPI) is the organisation that represents the interests of the recording industry worldwide. It is a non-profit members' organisation registered in Switzerland and founded in Italy in 1 ...
and RIAA, Philips
Koninklijke Philips N.V. (), commonly shortened to Philips, is a Dutch multinational conglomerate corporation that was founded in Eindhoven in 1891. Since 1997, it has been mostly headquartered in Amsterdam, though the Benelux headquarters i ...
developed the ''Recorder Identification Code'' (RID) to allow media to be uniquely associated with the recorder that has written it. This standard is contained in the Rainbow Books
The Rainbow Books are a collection of CD format specifications.
''Red Book'' (1980)
*CD-DA (''Digital Audio'') – standardized as IEC 60908
**CD-Text—a 1996 extension to CD-DA
** CD-MIDI—part of the original red-book standard
**CD+G (' ...
. The RID-Code consists of a supplier code (e.g. "PHI" for Philips), a model number and the unique ID of the recorder. Quoting Philips, the RID "enables a trace for each disc back to the exact machine on which it was made using coded information in the recording itself. The use of the RID code is mandatory."
Although the RID was introduced for music and video industry purposes, the RID is included on every disc written by every drive, including data and backup discs. The value of the RID is questionable as it is (currently) impossible to locate any individual recorder due to there being no database.
Source Identification Code
The Source Identification Code (SID) is an eight character supplier code that is placed on optical discs by the manufacturer. The SID identifies not only manufacturer, but also the individual factory and machine that produced the disc.
According to Phillips, the administrator of the SID codes, the SID code provides an optical disc production facility with the means to identify all discs mastered or replicated in its plant, including the specific Laser Beam Recorder (LBR) signal processor or mould that produced a particular stamper or disc.
Use of RID and SID together in forensics
The standard use of RID and SID mean that each disc written contains a record of the machine that produced a disc (the SID), and which drive wrote it (the RID). This combined knowledge may be very useful to law enforcement, to investigative agencies, and to private or corporate investigators.
A significant motivation for introducing the SID code was to identify disc manufacturing plants producing unauthorised copies of commercial CDs. By the 1990s, the production process for CDs had evolved from requiring a "clean-room" environment involving multiple processes, this demanding a substantial investment and likely to be confined to "responsible" organisations, into an activity that could be undertaken with "mono-liner" equipment, this having been developed in the late 1980s and capable of packaging "the whole process into a single box" that could occupy "no more space than a couple of office desks". Consequently, the CD manufacturing industry had grown to include less reputable organisations and, by 1994, could produce a volume of discs twice that of the estimated demand for "legitimate CDs", with music industry organisations claiming that illicit copies were outselling legitimate copies by significant margins in some markets. Philips and the IFPI envisaged that combinations of codes, each identifying a disc mastering establishment and the manufacturing plant used to make a particular disc, would assist in identifying those responsible for illicit CD production. However, the scheme relied on existing manufacturing plants upgrading their equipment to support the introduction of this measure, and the accompanying challenge of convincing such facilities was perceived as "a little difficult" in cases where those facilities were already involved in making considerable numbers of illicit discs.
See also
* Computer hardware
* Cue sheet (music software)
A cue sheet, or cue file, is a metadata file which describes how the tracks of a CD or DVD are laid out. Cue sheets are stored as plain text files and commonly have a filename extension. CDRWIN first introduced cue sheets, which are now suppo ...
* Floptical
Floptical refers to a type of floppy disk drive that combines magnetic and optical technologies to store data on media similar to standard -inch floppy disks. The name is a portmanteau of the words "floppy" and "optical". It refers specifically t ...
* ISO image
An optical disc image (or ISO image, from the ISO 9660 file system used with CD-ROM media) is a disk image that contains everything that would be written to an optical disc, disk sector by disc sector, including the optical disc file system. ...
* List of optical disc authoring software
This is a list of optical disc authoring software.
Open source
Multi-platform
* cdrtools, a comprehensive command line-based set of tools for creating and burning CDs, DVDs and Blu-rays
* cdrkit, a fork of cdrtools by the Debian project
* cdr ...
* MultiLevel Recording
MultiLevel Recording (ML, also known as M-ary) was a technology originally developed by Optex CorporationEarman, Allen, "Optical Data Storage With Electron Trapping Materials Using M-ary Data Channel Coding," Proceedings of the Optical Data Storag ...
* Optical disc authoring
Optical disc authoring, including DVD and Blu-ray Disc authoring, is the process of assembling source material—video, audio or other data—into the proper logical volume format to then be recorded ("burned") onto an optical disc (ty ...
* Optical disc recording technologies
Optical disc authoring requires a number of different optical disc recorder technologies working in tandem, from the optical disc media to the firmware to the control electronics of the optical disc drive.
Types of recordable optical disc
The ...
* Optical jukebox
An optical jukebox is a robotic data storage device that can automatically load and unload optical discs, such as Compact Disc, DVD, Ultra Density Optical or Blu-ray and can provide terabytes (TB) or petabytes (PB) of tertiary storage. The de ...
* Phase-change Dual
Phase-change Dual (or Phase-change Disc) is a rewritable optical disc and a standard for it, developed by Matsushita Electric Industrial Co. , Ltd. in April 1995.
It has a capacity of 650 MB on one side, and the size of the disc is 12 cm in d ...
* Receiver (radio)
* Ripping
Ripping is extracting all or parts of digital content from a container. Originally, it meant to rip music out of Commodore 64 games. Later, the term was used to extract WAV or MP3 format files from digital audio CDs, but got applied as well to e ...
Notes
References
External links
*
*
Understanding CD-R & CD-RW
{{Compact disc
American inventions
Audio storage
Optical computer storage
Disc drive
Japanese inventions
Video storage