A membrane keyboard is a

computer keyboard A computer keyboard is a peripheral input device modeled after the typewriter keyboard which uses an arrangement of buttons or keys to act as mechanical levers or electronic switches. Replacing early punched cards and paper tape technology ...

whose "keys" are not separate,

moving parts Machines include both fixed and moving parts. The moving parts have controlled and constrained motions. Moving parts are machine components excluding any moving fluids, such as fuel, coolant or hydraulic fluid. Moving parts also do not include ...

, as with the majority of other keyboards, but rather are pressure pads that have only outlines and

symbol A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different conc ...

s printed on a flat, flexible surface. Very little, if any,

tactile feedback In physiology, the somatosensory system is the network of neural structures in the brain and body that produce the perception of touch (haptic perception), as well as temperature (thermoception), body position (proprioception), and pain. It i ...

is felt when using such a keyboard. Membrane keyboards work by electrical contact between the keyboard surface and the underlying circuits when keytop areas are pressed. These models were used with some early 1980s home computers, enjoying wide adoption in consumer electronics devices. The keyboards are quite inexpensive to mass-produce, and are more resistant against dirt and liquids than most other keyboards. However, due to a low or non-existent tactile feedback, most people have difficulty typing with them, especially when larger numbers of characters are being typed.

Chiclet keyboard A chiclet keyboard or island-style keyboard is a computer keyboard with keys that form an array of small, flat rectangular or lozenge-shaped rubber or plastic keys that look like erasers or "Chiclets", a brand of chewing gum manufactured in the s ...

s were a slight improvement, at least allowing individual keys to be felt to some extent. Aside from early hobbyist/kit/home computers and some

video game console A video game console is an electronic device that Input/output, outputs a video signal or image to display a video game that can be played with a game controller. These may be home video game console, home consoles, which are generally placed i ...

s, membrane-based

QWERTY QWERTY () is a keyboard layout for Latin-script alphabets. The name comes from the order of the first six Computer keyboard keys#Types, keys on the top left letter row of the keyboard ( ). The QWERTY design is based on a layout created f ...

keyboards are used in some industrial computer systems, and are also found as portable, even "rollable-collapsible" designs for

PDA PDA may refer to: Science and technology * Patron-driven acquisition, a mechanism for libraries to purchase books *Personal digital assistant, a mobile device * Photodiode array, a type of detector * Polydiacetylenes, a family of conducting poly ...

s and other pocket computing devices. Smaller, specialised membrane keyboards, typically numeric-and-a-few-control-keys only, have been used in access control systems (for buildings and restricted areas), simple handheld calculators, domestic

remote control In electronics, a remote control (also known as a remote or clicker) is an electronic device used to operate another device from a distance, usually wirelessly. In consumer electronics, a remote control can be used to operate devices such as ...

keypads, microwave ovens, and other similar devices where the amount of typing is relatively small or infrequent, such as cell phones. Modern PC keyboards are essentially a membrane keyboard mechanism covered with an array of dome switches which give positive tactile feedback.

Mechanism

file:Membrane keyboard diagram FULL SCALE.png, Cross-section diagram of a typical membrane keyboard. The thickness of the bottom three layers has been exaggerated for clarity; in reality, they are not much thicker than pieces of paper or thin cardstock. The membrane keyboard consists of three layers; two of these are membrane layers containing conductive traces. The center layer is a "spacer" containing holes wherever a "key" exists. It keeps the other two layers separated. Under normal conditions, the switch (key) is open, because current cannot cross the non-conductive gap between the traces on the bottom layer. However, when the top layer is pressed down (with a finger), it makes contact with the bottom layer. The conductive traces on the underside of the top layer can then bridge the gap, allowing current to flow. The switch is now "closed", and the parent device registers a keypress. Many applications benefit from the sealed nature of the membrane keypad. Feedback can easily be provided to the user via audible means (e.g. a beep) or visually (lights or via the display itself), or via both means together. For additional wear resistance, a simple, easily replaceable protective clear sheet can be placed in front of the membrane. Membrane keyboards are widely used in consumer electronics, industrial, commercial, scientific and military equipment. Inside Computer keyboard

Mechanism

See also