Browse Prior Art Database

Miniature Optical Keyboard

IP.com Disclosure Number: IPCOM000078920D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Ludeman, CP: AUTHOR

Abstract

A miniature keyboard is available for hand-held calculators, wrist-worn terminals and the like, by optically coupling light from a light duct to a light-sensitive device.

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Miniature Optical Keyboard

A miniature keyboard is available for hand-held calculators, wrist-worn terminals and the like, by optically coupling light from a light duct to a light- sensitive device.

In Fig. 1, light-sensitive devices 10 and light sources 12, typically monochromatic light-emitting diodes are mounted on a circuit board 14. Power input and signal output is provided through pads 16. The light emitted by the light sources is optically coupled into a stylus guide and light duct 18, which is transparent and of such color as to transmit only that wavelength emitted by the light sources 12. A quiescent light flux is resident in the stylus guide and light duct 18. Light barriers 20 (see Fig. 2) exclude the light flux from those portions of the guide and duct 18 which covers the light-sensitive devices 10.

Operation of the keyboard is initiated by inserting a stylus 22 into an appropriate guide hole in the stylus guide and light duct 18. The stylus includes a transparent tip portion 24, which allows a portion of the resident light flux to be optically coupled into the associated light-sensitive device 10. The coupled light flux causes operation of the light-sensitive device 10. The number of light sources 12 required is dependent only upon the resident light flux necessary for reliable operation.

Fig. 3 shows an alternate approach where light from the duct 18 is concentrated on the light-sensitive device 10, which is in an "ON" state. Insertion of a stylus...