Capacitive touch keyboard

• US 6,657,616 B2
• Filed: 03/16/2001
• Issued: 12/02/2003
• Est. Priority Date: 03/16/2001
• Status: Expired due to Fees

• Current Assignee: Invensys Appliance Controls
• Original Assignee: Invensys Appliance Controls
• Inventors: Sims, Michael J.
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): Patel, Nitin
• Application Number:
  US09/809,974
• Publication Number:
  US 20020130848A1
• Time in Patent Office: 991 Days
• Field of Search: 345/173, 345/174, 178/18-1-, 178/18.05, 178/18.06, 178/19.03, 455/90
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0202 Constructional details or processes of manufacture of the input device
• CPC Class Codes: G06F 3/023 Arrangements for converting discrete items of information into a coded form, e.g. arrangements for interpreting keyboard generated codes as alphanumeric codes, operand codes or instruction codes
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard

Abstract

A touch sensor is provided which detects manual contact by a user to actuate a controlled device. The touch sensor includes a substrate, an RF signal transmitter including a plurality of first conductors, and an RF signal receiver including a plurality of second conductors. The first and second conductors are located in spaced, interdigitated alignment with one another on the substrate, to form a key having a geometry which affords substantial coverage thereof by a human appendage. The RF signal receiver includes an RF signal amplifier electrically coupled to the second conductors. A processor is electrically coupled to the RF signal receiver to detect variations in signal strength corresponding to coverage of the key by a human appendage to selectively actuate the controlled device.

Claims

1. A touch sensor for detecting manual contact by a user for actuating a controlled device, the touch sensor comprising:

a substrate;

an RF signal transmitter including a plurality of first conductors;

an RF signal receiver including a plurality of second conductors;

said first and second conductors disposed in spaced, interdigitated alignment with one another on the substrate, to form a key having a geometry which affords substantial coverage thereof by a human appendage;

the RF signal receiver including an RF signal amplifier electrically coupled to the second conductors;

a processor electrically coupled to the RF signal receiver to detect variations in signal strength corresponding to selective coverage of said key by a human appendage to selectively actuate the controlled device.

2. The sensor of claim 1, wherein the RF signal transmitter further comprises an RF signal generator.

3. The sensor of claim 2, comprising a plurality of keys.

4. The sensor of claim 3, wherein the keys are arranged in a matrix.

5. The sensor of claim 2, comprising a multiplexer coupled to the RF signal generator and to RF signal transmitters of a plurality of keys, wherein the RF signal generator is sequentially coupled to each of the RF signal transmitters.

6. The sensor of claim 5, wherein said processor is electrically coupled to said multiplexer and controls operation of said multiplexer.

7. The sensor of claim 1, further comprising a dielectric material superposed with said substrate, said dielectric adapted for said engagement by the human appendage during said coverage.

8. The sensor of claim 1, wherein the amplifier comprises a common emitter amplifier having an NPN transistor and a PNP transistor.

9. The sensor of claim 1, wherein the RF signal receiver further comprises a peak detector electrically coupled to the RF signal amplifier.

10. The sensor of claim 9, wherein said peak detector comprises a diode disposed in series with a resistor/capacitor pair.

11. The sensor of claim 10, further comprising an A/D converter coupled to said peak detector.

12. The sensor of claim 11, wherein said A/D converter is coupled to the processor.

13. The sensor of claim 12, wherein the RF signal transmitter further comprises an RF signal generator.

14. The sensor of claim 13, comprising a multiplexer coupled to the RF signal generator and to the RF signal transmitters of a plurality of keys, wherein the RF signal generator is sequentially coupled to each of the RF signal transmitters, said processor being electrically coupled to said multiplexer to control operation of said multiplexer.

15. The sensor of claim 1, wherein the substrate is glass.

16. The sensor of claim 1, wherein the substrate is plastic.

17. A touch sensor for detecting manual contact by a user for actuating a controlled device, the touch sensor comprising:

a substrate;

an RF signal transmitter including a RF signal generator and plurality of first conductors;

an RF signal receiver including a plurality of second conductors;

said first and second conductors disposed in spaced, interdigitated alignment with one another on the substrate, to form a key having a geometry which affords substantial coverage thereof by a human appendage;

the RF signal receiver including an RF signal amplifier electrically coupled to the second conductors;

a processor electrically coupled to the RF signal receiver to detect variations in signal strength corresponding to selective coverage of said key by a human appendage to selectively actuate the controlled device;

wherein the RF signal receiver receives a baseline signal when the first and second conductors are free from said coverage, and the RF signal receiver receives an activation signal which is discrete from the baseline signal upon said coverage, and an absolute value of the activation signal is less than an absolute value of the baseline signal.

18. A method for detecting manual contact by a user for actuating a controlled device, the method comprising the steps of:

(a) providing a substrate;

(b) providing an RF signal transmitter including a plurality of first conductors;

(c) providing an RF signal receiver including a plurality of second conductors coupled to an RF signal amplifier;

(d) disposing the first and second conductors in spaced, interdigitated alignment with one another on the substrate, to form a key having a geometry which affords substantial coverage thereof by a human appendage;

(e) electrically coupling a processor to the RF signal receiver;

(f) using the processor to detect variations in signal strength corresponding to selective coverage of said key by a human appendage to selectively actuate the controlled device.