Browse Prior Art Database

Optical Keyboard

IP.com Disclosure Number: IPCOM000051996D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Duncan, WS: AUTHOR [+2]

Abstract

An optical keyboard includes a molded plastic block having arrays of intersecting light channels which are selectively blocked upon key actuation. A scanned light source is used in conjunction with a single detector.

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Optical Keyboard

An optical keyboard includes a molded plastic block having arrays of intersecting light channels which are selectively blocked upon key actuation. A scanned light source is used in conjunction with a single detector.

Optical keyboard 11 (Fig. 1) includes molded plastic block 13 having light channels 15 and 17 running therethrough. Key actuators 19 having keys 21 and light interrupters 23, 25 are placed so that light interrupter 23 interrupts a light channel 17 and light interrupter 25 interrupts a light channel 15 upon key 21 depression. Light source 27 (Fig. 2) is placed adjacent one end of each light channel 17, and light source 29 is placed adjacent one end of each light channel
15. Fiber-optic cables 31 connect the opposite ends of the light channels to a light detector 33. The light sources 27, 29, which may be light-emitting diodes or laser sources, are pulsed sequentially by a clocking circuit which is also utilized to gate the output of detector 33.

Depression of a keybutton 21 blocks the generation of light through a unique one of each of the channels 15 and 17, thereby providing a logical indication of which of the keys 21 is depressed. That is, during a keyboard scan, there is no output from sensor 33 when the clocking circuit impulses a light source 29 aligned with the blocked light channel 15 and there is no output when a light source 27 aligned with the blocked channel 17 is impulsed. The absence of these two outputs indicates the c...