Browse Prior Art Database

Data Entry Error Detection with an Optical Keyboard

IP.com Disclosure Number: IPCOM000077361D
Original Publication Date: 1972-Jul-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Bowen, AJ: AUTHOR

Abstract

An optical keyboard assembly includes a molded cover 10 which presents a series of light channels 11 formed by a series of cross-talk separator walls 12. At one end of each channel 11 light is delivered from a light source 13 in the form of a light-emitting diode (LED), which is reflected by mirror 14 and passes through a lens 15 and a slit aperture 16. At the opposite end of each channel 11 light is received through a slit aperture 17 and lens 18, and reflected by a mirror 19 to a phototransistor 20. Overlying inlet slit aperture 16 is a sheet of linear polarizer material 21 and overlying outlet slit aperture 17 is a sheet of linear analyzer material 22.

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Data Entry Error Detection with an Optical Keyboard

An optical keyboard assembly includes a molded cover 10 which presents a series of light channels 11 formed by a series of cross-talk separator walls 12. At one end of each channel 11 light is delivered from a light source 13 in the form of a light-emitting diode (LED), which is reflected by mirror 14 and passes through a lens 15 and a slit aperture 16. At the opposite end of each channel 11 light is received through a slit aperture 17 and lens 18, and reflected by a mirror 19 to a phototransistor 20. Overlying inlet slit aperture 16 is a sheet of linear polarizer material 21 and overlying outlet slit aperture 17 is a sheet of linear analyzer material 22.

As seen in Fig. 3, when light is passed from a source through a linear polarizer 21 and linear analyzer 22 to photodetector 20, the latter passes light when either no half-wave retarder 24 is present or an even number of such retarders are interposed between polarizer 21 and analyzer 22. When an odd number of half-wave retarders 24 are interposed between Polarizer 21 and analyzer 22, photodetector 20 sees no light.

In the keyboard, each key assembly, not shown, through a key lever 25 actuates an encoding lever 26 formed of half-wave retarder material. Each encoding lever 26 pivots about the axis of rod 28; has a tab 30 at each of the timing positions, T1 and T2; and tabs at positions C1 through C8 in accordance with the code assigned to the associated key. The...