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Non-Mechanical Keyboard

IP.com Disclosure Number: IPCOM000097682D
Original Publication Date: 1961-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Goddard, WA: AUTHOR

Abstract

To provide a keyboard which is actuated by body capacitance when an operator touches a key, an alternating current field is applied across a pair of plates E(1) and E(2). This ionizes the gas in each of a plurality of neon lamps N(0)...N(9) disposed between the plates. One electrode of each lamp is connected through filter resistors R(f) and filter capacitors C(f) to the appropriate ones of the conductors M(1), M(2), M(4) and M(8). The latter are in a recoding matrix whose conductors provide a binary coded output signal representing the actuated key.

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Non-Mechanical Keyboard

To provide a keyboard which is actuated by body capacitance when an operator touches a key, an alternating current field is applied across a pair of plates E(1) and E(2). This ionizes the gas in each of a plurality of neon lamps N(0)...N(9) disposed between the plates. One electrode of each lamp is connected through filter resistors R(f) and filter capacitors C(f) to the appropriate ones of the conductors M(1), M(2), M(4) and M(8). The latter are in a recoding matrix whose conductors provide a binary coded output signal representing the actuated key.

Each of the keys K(0)...K(9) is electrically connected to one electrode of its corresponding lamp. Trimmer capacitors C(t) are provided for each neon lamp to balance the stray capacitance. In the absence of a human hand on one of the keys, the recode matrix lines are at zero potential with respect to ground. When a key is touched, the body capacitance is effective to disturb the balance of the network. The electrode connected to the actuated key becomes negative with respect to the other electrode of this lamp. This change in potential of the electrode varies the potential of the matrix lines to which the electrode is connected to produce an output pulse to the recoding matrix. Filter elements R(f) and C(f) maintain a steady D. C. signal to the recode matrix so long as the key is touched.

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