Membrane keyboard
Encyclopedia
Computer keyboard
In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
whose "keys" are not separate, moving parts
Moving parts
The moving parts of a machine are those parts of it that move. Machines comprise both moving and fixed parts. The moving parts have controlled and constrained motions....
, as with the majority of other keyboards, but rather are pressure pads that have only outline
Outline
An outline is a list of the main features of a given topic, often used as a rough draft or summary of the content of a document. A hierarchical outline is a list arranged to show hierarchical relationships, and is a type of tree structure....
s and symbol
Symbol
A symbol is something which represents an idea, a physical entity or a process but is distinct from it. The purpose of a symbol is to communicate meaning. For example, a red octagon may be a symbol for "STOP". On a map, a picture of a tent might represent a campsite. Numerals are symbols for...
s printed on a flat, flexible surface. Very little, if any, tactile feedback is felt when using such a keyboard, and error-free blind typing is difficult.
Membrane keyboards, which work by electrical contact between the keyboard surface and the underlying circuits when keytop areas are pressed, were used with some early 1980s home computer
Home computer
Home computers were a class of microcomputers entering the market in 1977, and becoming increasingly 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 single nontechnical user...
s, and have been much used in consumer electronics devices. The keyboards are very inexpensive to mass produce, and are more resistant against dirt and liquids than most other keyboards, but due to the low or non-existent amount of tactile feedback provided, most people have difficulty typing with them, especially when large numbers of characters need to be typed. Chiclet keyboard
Chiclet keyboard
A chiclet keyboard or island-style keyboard is a computer keyboard built with 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 shape of small squares with rounded corners...
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
Video game console
A video game console is an interactive entertainment computer or customized computer system that produces a video display signal which can be used with a display device to display a video game...
s, membrane-based QWERTY
QWERTY
QWERTY is the most common modern-day keyboard layout. The name comes from the first six letters appearing in the topleft letter row of the keyboard, read left to right: Q-W-E-R-T-Y. The QWERTY design is based on a layout created for the Sholes and Glidden typewriter and sold to Remington in the...
keyboards are used in some industrial computer systems, and are also found as portable, even "rollable-collapsible" designs for PDA
Personal digital assistant
A personal digital assistant , also known as a palmtop computer, or personal data assistant, is a mobile device that functions as a personal information manager. Current PDAs often have the ability to connect to the Internet...
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
Remote control
A remote control is a component of an electronics device, most commonly a television set, used for operating the television device wirelessly from a short line-of-sight distance.The remote control is usually contracted to remote...
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.
How it works
As can be seen from the diagram below, the membrane keyboard basically 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 apart.
Typical applications include;
- Industrial controls
- Access control systems
- Medical equipment
- Telecommunications apparatus
- Telephone systems
- Household appliances
- Security systems
Source, Instrument Component Labels Limited, Membrane keypads
List of computers with membrane keyboards
QWERTY layouts unless otherwise specified- Atari 400Atari 8-bit familyThe Atari 8-bit family is a series of 8-bit home computers manufactured from 1979 to 1992. All are based on the MOS Technology 6502 CPU and were the first home computers designed with custom coprocessor chips...
(full-travel replacement keyboards much like those that came with the Atari 800 were available) - Cambridge Z88Cambridge Z88The Cambridge Computer Z88 is an A4-size, lightweight, portable Z80-based computer with a built-in combined word processing/spreadsheet/database application called PipeDream, along with several other applications and utilities, such as a Z80-version of the BBC BASIC programming language.The Z88...
(arguably a mix between a membrane and chiclet keyboard) - Elektronika BK-0010, in early versions (it was a Russian home computer, hence the JCUKEN layout)
- Magnavox Odyssey²Magnavox Odyssey²The Magnavox Odyssey², known in Europe as the Philips Videopac G7000, in Brazil as the Philips Odyssey, in the United States as the Magnavox Odyssey² and the Philips Odyssey², and also by many other names, is a video game console released in 1978.In the early 1970s, Magnavox was an innovator in the...
, also known as the PhilipsPhilipsKoninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....
Videopac G7000 video game console - RCARCARCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor...
COSMAC VIPCOSMAC VIPThe COSMAC VIP was an early microcomputer that was aimed at video games. For a price of US$275, it could be purchased from RCA by mail order. It came in kit form, and had to be assembled. Its dimensions were 22 x 28 cm, and it had a RCA 1802 processor; along with a crystal clock operating at 1.76...
, a do-it-yourself (DIY) kit computer with 16-key hexHexadecimalIn mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
keypad - Robotron Z1013, Eastern-German home computer (alphabetical layout)
- SEGASega, usually styled as SEGA, is a multinational video game software developer and an arcade software and hardware development company headquartered in Ōta, Tokyo, Japan, with various offices around the world...
SC-3000, a computer version of an early SEGA game console - Science of Cambridge Microcomputer Kit 14 (MK14MK14The Microcomputer Kit 14, or MK14 was a computer kit sold by Science of Cambridge of the United Kingdom, first introduced in 1977 for UK£39.95. The MK14 eventually sold over 50,000 units. It used a National Semiconductor SC/MP CPU , 256 bytes of random access memory which was directly expandable...
); the initial version had a 20-key extended hex keypad - Sinclair ZX80Sinclair ZX80The Sinclair ZX80 is a home computer brought to market in 1980 by Science of Cambridge Ltd. . It is notable for being the first computer available in the United Kingdom for less than a hundred pounds...
, a pioneering British home computer that was available as a DIY kit - Sinclair ZX81Sinclair ZX81The ZX81 was a home computer produced by Sinclair Research and manufactured in Scotland by Timex Corporation. It was launched in the United Kingdom in March 1981 as the successor to Sinclair's ZX80 and was designed to be a low-cost introduction to home computing for the general public...
(similar to the preceding entry) - SynertekSynertekSynertek, Inc. was an American semiconductor manufacturer founded in 1973. The initial founding group consisted of Bob Schreiner , Dan Floyd, Zvi Grinfas, Jack Balletto, and Gunnar Wetlesen. The manufacturing technology was MOS/LSI...
SYM-1SYM-1The SYM-1 was a single board "trainer" computer produced by Synertek circa 1978. Originally called the VIM-1 , that name was changed for legal reasons sometime between April and August 1978....
, a sibling of the MOSMOS TechnologyMOS Technology, Inc., also known as CSG , was a semiconductor design and fabrication company based in Norristown, Pennsylvania, in the United States. It is most famous for its 6502 microprocessor, and various designs for Commodore International's range of home computers.-History:MOS Technology, Inc...
/CBMCommodore InternationalCommodore is the commonly used name for Commodore Business Machines , the U.S.-based home computer manufacturer and electronics manufacturer headquartered in West Chester, Pennsylvania, which also housed Commodore's corporate parent company, Commodore International Limited...
KIM-1KIM-1The KIM-1, short for Keyboard Input Monitor, was a small 6502-based single-board computer developed and produced by MOS Technology, Inc. and launched in 1976...
with a 29-key extended hex keypad - Timex Sinclair 1000Timex Sinclair 1000The Timex Sinclair 1000 was the first computer produced by Timex Sinclair, a joint-venture between Timex Corporation and Sinclair Research. It was launched in July 1982....
(a U.S. version of the ZX81)