Browse Prior Art Database

Non Mechanical Keyboard

IP.com Disclosure Number: IPCOM000095632D
Original Publication Date: 1964-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Goddard, WA: AUTHOR

Abstract

The keyboard is actuated by body conductance, when an operator touches a key.

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Non Mechanical Keyboard

The keyboard is actuated by body conductance, when an operator touches a key.

A drive pulse is applied to two delay lines. One serves essentially the purpose of a clock. The other provides pulses which identify characters. At each of the taps 0 ... 9 of the character delay line, there s connected a small capacitance C, the other terminal of which is c connected to a biased diode D. The other terminal of each of the diodes is connected in parallel to line A. Metal contacts on the keyboard keys K0 ... K9 are connected through relatively large capacitors Cx to the diodes. When a key is touched by the human finger, the input to the diode is essentially grounded through Cx and the body capacitance so that no character pulse is emitted on line A for that particular character. Pulses appear on line 13 at all character times, and lines A and B are connected to gate 10. The latter provides an output 11 only when a pulse is received on line B but no pulse is received on line A.

Thus, in operation, a single drive pulse is applied to both the character delay line and the local clock line and is propagated down the delay lines. Output pulses appear from the corresponding taps along the delay lines simultaneously on lines A and B until the touched key is reached. At that time, an output pulse appears on line B and no output pulse appears on line A. Thus, gate 10 provides an output pulse which is a time-dependent indication of the key touched.

Decoding c...