Chiclet keyboard

From Free net encyclopedia

A chiclet keyboard is slang for a computer keyboard built with an array of small, flat rectangular or lozenge-shaped rubber or plastic keys that look like erasers or pieces of chewing gum. The term comes from "Chiclets", the brand name of a variety of chewing gum.

Vendors unanimously liked the chiclet keyboard because it was cheap to produce, and many early home computers (notably the ZX Spectrum), portables and laptop computers were launched with it. However, consumers rejected it with almost equal unanimity, even though it was not quite as unpleasant to work with as the membrane keyboard. After 1985, chiclet keyboards were not often seen other than on some digital calculator watches, small handheld calculators, and cheap, nonexpandable PDAs.

The expression "chiclet keyboard" is not common to every country. For example, in the UK (where Chiclets gum is not sold), it is more often referred to as either a dead-flesh keyboard (from the feel of the keys) or simply a rubber-keyed keyboard. In Norway, the term eraser keyboard was commonly used (from the keys' likeness to pencil erasers).

See also: keyboard technology

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How it works

In some (but not all) versions of the chiclet keyboard, the bottom three layers are essentially the same as those in the membrane keyboard. In both cases, a keypress is registered when the top layer is forced through a hole to touch the bottom layer. For every key, the conductive traces on the bottom layer are normally separated by a non-conductive gap. Electrical current cannot flow between them; the switch is open. However, when pushed down, conductive material on the underside of the top layer bridges the gap between those traces; the switch is closed, current can flow, and a keypress is registered.

Unlike the membrane keyboard, where the user presses directly onto the top membrane layer, this form of chiclet keyboard places a set of moulded rubber keys above this. The user pushes the key, and under sufficient pressure the rubber is distorted enough to force the top membrane layer against the bottom layer. This provides a greater feeling of movement than a simple membrane keyboard.

The following diagram illustrates this version of the chiclet keyboard:-

Image:Chiclet keyboard medium.png
Other versions of the chiclet keyboard omit the upper membrane and hole/spacer layers; instead the underside of the rubber keys themselves have a conductive coating. When the key is pushed, the conductive underside makes contact with the traces on the bottom layer and completes the circuit.

The dome switch keyboards used with a large proportion of modern PCs are technically similar to chiclet keyboards. However, the rubber keys are replaced with rubber domes, and hard plastic keytops rest on top of these.

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