Keyboard and switches for keyboards
AssigneeNational Research Development Corporation
InventorsLionel George Ripley, Richard Lawrence Grimsdale
Life of this patent
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Abstract
A switch for use in a keyboard consists of an input light pipe, one or more output light pipes and means selectively operable to cause light to be reflected from the input light pipe into the output light pipes. The output light pipes are preferably connected to photodetectors which detect whether or not the switch is actuated by determining the amount of light incident thereon. When such a switch is to be used in a keyboard which is required to produce a coded output, one photodetector is provided for each digit of the code and output light pipes on the various switches are connected to the photodetectors in accordance with the code.
Claims6
A keyboard comprising:
- a light source,
- a plurality of optical switches,
- a plurality of photodetectors,
- a plurality of output light pipes for each switch selectively connecting the switch to a plurality of photodetectors,
- one input light pipe for each switch being connected to the light source,
- each optical switch comprising light conduction means to transmit light from the input light pipe to the plurality of output light pipes,
- the amount of light from each input light pipe entering the light conduction means for transmission to the plurality of output light pipes being variable between a first level when the switch is actuated and a second level when the switch is not actuated,
- each plurality of output light pipes being connected to a different combination of photodetectors which generate a signal consisting of a different multibit binary code for each switch.
Dependencies are inferred from the claim text.