A membrane keyboard is a

computer keyboard A computer keyboard is a built-in or peripheral input device modeled after the typewriter keyboard which uses an arrangement of buttons or Push-button, keys to act as Mechanical keyboard, mechanical levers or Electronic switching system, electro ...

whose keys are not separate, moving parts, as with the majority of other keyboards, but rather are pressure pads that have only outlines and

symbol A symbol is a mark, Sign (semiotics), sign, or word that indicates, signifies, or is understood as representing an idea, physical object, object, or wikt:relationship, relationship. Symbols allow people to go beyond what is known or seen by cr ...

s printed on a flat, flexible surface. Very little tactile feedback is felt when using such a keyboard.

History

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 computer Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a s ...

s which lead to greater adoption of the design. The keyboards are inexpensive to produce, and are more resistant against dirt and liquids than some other keyboard types. However, due to a low or non-existent tactile feedback, some people have reported difficulty typing with them, especially when larger numbers of characters are being typed. Chiclet keyboards are a variation of the design.

Usage

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 typically be played with a game controller. These may be home video game console, home consoles, which are generally ...

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 letter row of the keyboard: . The QWERTY design is based on a layout included in the Sh ...

keyboards are used in some industrial computer systems, and are also found as portable, even "rollable-collapsible" designs for PDAs and other pocket computing devices. Smaller, specialized 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 A remote control, also known colloquially as a remote or clicker, is an consumer electronics, electronic device used to operate another device from a distance, usually wirelessly. In consumer electronics, a remote control can be used to operat ...

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 (typically made out of Polyethylene terephthalate or PET) keyboard consists of three layers: two layers containing traces of conductive ink and the center layer is a "spacer" containing holes wherever a two conductive "key" pads count touch upon being pressed. The third layer keeps the other two layers separated in order to prevent short-circuit. 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

References

{{DEFAULTSORT:Membrane Keyboard Computer keyboard types

History

Usage

Mechanism

See also

References