Browse Prior Art Database

Optical Keyboard Device and Technique

IP.com Disclosure Number: IPCOM000047363D
Original Publication Date: 1983-Nov-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Callens, P: AUTHOR

Abstract

This article describes a device and technique which eliminate the electromechanical keyboard in a CRT-based VDU (Video Display Unit). The device and technique may be described as follows: Part of conventional CRT (Fig. 1) of the VDU is devoted to displaying N light spots, e.g., N = 4 x 20 = 80 zones. Each spot is lightened at regular and periodic times tn + T counted from an origin t in such a way that the detection of the spot occurrence defines the zone which is lightened. The photosensors and the circuitry necessary to detect the spot occurrence are deposited in a plastic film which is stuck on the screen (Fig. 2). On the visible side of the plastic film, the 4 x 20 zones are printed with the keyboard characters, e.g., Q W E R T Y.

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Optical Keyboard Device and Technique

This article describes a device and technique which eliminate the electromechanical keyboard in a CRT-based VDU (Video Display Unit). The device and technique may be described as follows: Part of conventional CRT (Fig. 1) of the VDU is devoted to displaying N light spots, e.g., N = 4 x 20 = 80 zones. Each spot is lightened at regular and periodic times tn + T counted from an origin t in such a way that the detection of the spot occurrence defines the zone which is lightened. The photosensors and the circuitry necessary to detect the spot occurrence are deposited in a plastic film which is stuck on the screen (Fig. 2). On the visible side of the plastic film, the 4 x 20 zones are printed with the keyboard characters, e.g., Q W E R T Y. On the invisible side, the thin film circuitry contains one photosensor for each of the 80 zones and corresponding spots. The light spots are analyzed by the photosensors and provide a train of pulses, sequentially timed for each of the 80 spots (n = 1 to n = N). The thin film also includes, on the visible side, 80 resistive (or capacitive) components which, if touched with the finger, enable the selection of the pulse corresponding to the zone which has been touched. A circuit measures the time occurrence of the selected pulse and produces the 7- or 8-bit code of the corresponding key.

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