Passive matrix addressing is an
addressing scheme used in early
liquid crystal displays (LCDs). It is a matrix addressing scheme, meaning that only ''m'' + ''n'' control signals are required to address an ''m'' × ''n'' display. A
pixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a Raster graphics, raster image, or the smallest addressable element in a dot matrix display device. In most digital display devices, p ...
in a passive matrix must maintain its state without active driving circuitry until it can be refreshed again.
The
signal
A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology.
In ...
is divided into a row or ''select signal'' and a column or ''video signal''. The select
voltage
Voltage, also known as (electrical) potential difference, electric pressure, or electric tension, is the difference in electric potential between two points. In a Electrostatics, static electric field, it corresponds to the Work (electrical), ...
determines the row that is being addressed and all ''n'' pixels on a row are addressed simultaneously. When
pixels
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest addressable element in a dot matrix display device. In most digital display devices, pixels are the sma ...
on a row are being addressed, a ''V
sel'' potential is applied, and all other rows are unselected with a ''V
unsel'' potential. The video signal or column potential is then applied with a potential for each ''m'' columns individually. An on-switched (lit)
pixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a Raster graphics, raster image, or the smallest addressable element in a dot matrix display device. In most digital display devices, p ...
corresponds to a ''V
on'', an off-switched (unlit) corresponds to a ''V
off'' potential.
The potential across
pixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a Raster graphics, raster image, or the smallest addressable element in a dot matrix display device. In most digital display devices, p ...
at selected row ''i'' and column ''j'' is
:
and
:
for the unselected rows.
This scheme has been expanded to define the limits of this type of addressing typical LCDs.
[T. N. Ruckmongathan, V. Arun, Babu Hemanth Kumar]
''Line-by-Line Addressing of RMS Responding Matrix Displays With Wavelets.''
Journal of Display Technology. Vol. 3, issue 4, pp. 413–420 December 2007.
Passive matrix addressed displays, such as
ferroelectric liquid crystal displays, do not need the switch component of an active matrix display, because they have built-in
bistability. Technology for
electronic paper
Electronic paper or intelligent paper, is a display device that reflects ambient light, mimicking the appearance of ordinary ink on paper – unlike conventional flat-panel displays which need additional energy to emit their own light. This may ...
also has a form of bistability. Displays with bistable pixel elements are addressed with a passive matrix addressing scheme, whereas
TFT LCD displays are addressed using
active addressing.
See also
*
Active matrix addressing
*
Pixel geometry
*
Liquid crystal display
A liquid-crystal display (LCD) is a flat-panel display or other Electro-optic modulator, electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers to display information. Liq ...
References
{{DEFAULTSORT:Passive Matrix Addressing
Digital imaging
Liquid crystal displays