# US 3,971,013 A · Touch keyboard

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 3,971,013 A
- Document ID: US3971013A
- Status: Granted
- Kind: A
- Application number: 05/570,990
- Filed: 1975-04-23
- Granted: 1976-07-20
- Earliest claimed: 1974-10-01
- Assignees: International Business Machines Corporation
- Inventors: Francis Loyola Challoner; Hemmige Desikachar Varadarajan
- Web page: https://patentgrep.com/patent/US3971013A

## CPC

- G06F 3/0488: using a touch-screen or digitiser, e.g. input of commands through traced gestures
- G06F 3/044: by capacitive means
- H03K 17/9622: {using a plurality of detectors, e.g. keyboard}
- H03K 17/98: having a plurality of control members, e.g. keyboard
- H03K 2017/9613: {using two electrodes per touch switch}
- H03K 2217/960745: Capacitive differential; e.g. comparison with reference capacitance
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)

## Abstract

A touch operated keyboard comprising an AC driven gas discharge panel display with conductive touch keys located to pick up an AC voltage from the stray field generated by the gas discharge panel is disclosed. A detector detects the drop in AC voltage level of a key due to the proximity of an operator's finger. The touch keys may be deposited upon the surface of the gas panel or upon a separate transparent sheet. The keyboard may be operated to change the information displayed by the gas panel.

## Claims

### Claim 1

A touch operated keyboard comprising:
an AC driven gas discharge panel display;
at least one conductive touch key located proximate said display to pick up an AC voltage from said stray field generated by the gas discharge panel; and
means to detect the drop in AC voltage level of said at least one key due to the proximity of an operator's finger.

### Claim 2 (depends on 1)

A keyboard as claimed in claim 1, in which each touch key overlays a display position on the gas discharge panel and the touch key is operable to change the information displayed in that position and/or any other positions.

### Claim 3 (depends on 1)

A keyboard as claimed in claim 1 in which said conductive key comprises a metallic layer deposited upon a surface of the gas discharge panel.

### Claim 4 (depends on 3)

A keyboard as claimed in claim 3, in which each touch key overlays a display position on the gas discharge panel and the touch key is operable to change the information displayed in that position and/or any other positions.

### Claim 5 (depends on 3)

A keyboard as claimed in claim 3, in which said metallic layer is transparent.

### Claim 6 (depends on 5)

A keyboard as claimed in claim 5, in which each touch key overlays a display position on the gas discharge panel and the touch key is operable to change the information displayed in that position and/or any other positions.

### Claim 7 (depends on 1)

A keyboard as claimed in claim 1 in which said conductive key comprises a metallic layer upon a sheet of transparent insulating material, and; said transparent sheet is placed over the surface of said gas discharge panel.

### Claim 8 (depends on 7)

A keyboard as claimed in claim 7, in which each touch key overlays a display position on the gas discharge panel and the touch key is operable to change the information displayed in that position and/or any other positions.

### Claim 9 (depends on 7)

A keyboard as claimed in claim 7, in which said metallic layer is transparent.

### Claim 10 (depends on 9)

A keyboard as claimed in claim 9, in which each touch key overlays a display position on the gas discharge panel and the touch key is operable to change the information displayed in that position and/or any other positions.