Touch switch with integral control circuit

• US 6,320,282 B1
• Filed: 01/19/1999
• Issued: 11/20/2001
• Est. Priority Date: 01/19/1999
• Status: Expired due to Term

• Current Assignee: Touchsensor Technologies LLC (Methode Electronics Incorporated)
• Original Assignee: Touchsensor Technologies LLC (Methode Electronics Incorporated)
• Inventors: Caldwell, David W.
• Primary Examiner(s): Ballato, Josie
• Assistant Examiner(s): DeBeradinis, Robert L.
• Application Number:
  US09/234,150
• Time in Patent Office: 1,036 Days
• Field of Search: 307/125, 307/116, 307/112, 361/280, 361/283.1, 361/288, 361/291, 200/600
• US Class Current: 307/125
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2217/96077 comprising an electrode which is floating

Abstract

A touch switch apparatus for detecting the presence of an object such as a human appendage, the apparatus having a touch pad and a local control circuit connected to the touch pad and to a controlled device. The touch pad preferable includes a first electrode and a second electrode spaced from and surrounding the first electrode. The control circuit is preferably in integrated circuit form. A signal is provided to the touch pad to generate an electric field thereabout. Introduction of a stimulus near the touch pad disturbs the electric field. The control circuit detects the electric field disturbance in and generates a control signal in response.

Claims

1. A touch switch apparatus for generating a control signal on an output line, comprising:

a touch pad comprising a first electrode and a second electrode in close proximity to said first electrode;

a first resistor electrically coupled to said first electrode;

a second resistor electrically coupled to said second electrode;

a control circuit in close proximity to said touch pad;

said control circuit electrically coupled to said first and second resistors;

said control circuit having an input node for receiving an input signal from a remote signal source;

said touch pad being configured to receive a field generation signal;

wherein said field generation signal causes an electric field to be generated about said touch pad;

said control circuit being responsive to a stimulus affecting said electric field;

said control circuit being configured to selectively generate a control signal in response to said stimulus affecting said electric field; and

said control circuit having an output node for transmitting said control signal on said output line to a remote device;

wherein each of said first and second resistors has a value such that said apparatus has a relatively low input impedance compared to the impedance of a contaminant in proximity to at least one of said first and said second electrodes.

2. A touch switch apparatus for generating a control signal on an output line, the apparatus comprising:

a touch pad comprising a first electrode and a second electrode in close proximity to said first electrode;

a control circuit in close proximity to said touch pad;

said control circuit being electrically coupled to said touch pad;

said control circuit having an input node for receiving an input signal from a remote signal source;

said touch pad being configured to receive a field generation signal;

wherein said field generation signal causes an electric field to be generated about said touch pad;

said control circuit being responsive to a stimulus affecting said electric field;

said control circuit being configured to selectively generate a control signal in response to said stimulus affecting said electric field; and

said control circuit having an output node for transmitting said control signal on said output line to a remote device;

wherein the voltage of said control signal on said output line is at a minimum value when said electric field proximate said second electrode is disturbed to a substantially equal or greater extent than said electric field proximate said first electrode.

3. A touch switch apparatus for generating a control signal on an output line, the apparatus comprising:

a touch pad comprising a first electrode and a second electrode in close proximity to said first electrode;

a control circuit in close proximity to said touch pad;

said control circuit being electrically coupled to said touch pad;

said control circuit having an input node for receiving an input signal from a remote signal source;

said touch pad being configured to receive a field generation signal;

wherein said field generation signal causes an electric field to be generated about said touch pad;

said control circuit being responsive to a stimulus affecting said electric field;

said control circuit being configured to selectively generate a control signal in response to said stimulus affecting said electric field; and

said control circuit having an output node for transmitting said control signal on said output line to a remote device;

wherein the voltage of said control signal on said output line is at a maximum value when said electric field proximate said second electrode is disturbed to a substantially equal or greater extent than said electric field proximate said first electrode.

4. A touch switch apparatus for generating a control signal on an output line, the apparatus comprising:

a touch pad comprising a first electrode and a second electrode in close proximity to said first electrode;

a control circuit in close proximity to said touch pad;

said control circuit being electrically coupled to said touch pad;

said control circuit having an input node for receiving an input signal from a remote signal source;

said touch pad being configured to receive a field generation signal;

wherein said field generation signal causes an electric field to be generated about said touch pad;

said control circuit being responsive to a stimulus affecting said electric field;

said control circuit being configured to selectively generate a control signal in response to said stimulus affecting said electric field; and

said control circuit having an output node for transmitting said control signal on said output line to a remote device;

wherein the voltage of said control signal on said output line is at a maximum value when said electric field about said first electrode is disturbed to a substantially greater extent than said electric field about said second electrode.

5. A touch switch apparatus for generating a control signal on an output line, the apparatus comprising:

a touch pad comprising a first electrode and a second electrode in close proximity to said first electrode;

a control circuit in close proximity to said touch pad;

said control circuit being electrically coupled to said touch pad;

said control circuit having an input node for receiving an input signal from a remote signal source;

said touch pad being configured to receive a field generation signal;

wherein said field generation signal causes an electric field to be generated about said touch pad;

said control circuit being responsive to a stimulus affecting said electric field;

said control circuit being configured to selectively generate a control signal in response to said stimulus affecting said electric field; and

said control circuit having an output node for transmitting said control signal on said output line to a remote device;

wherein the voltage of said control signal on said output line is at a minimum value when said electric field about said first electrode is disturbed to a substantially greater extent than said electric field about said second electrode.