Capacitive touch switch system for an audio device

• US 7,106,221 B2
• Filed: 04/30/2003
• Issued: 09/12/2006
• Est. Priority Date: 04/30/2003
• Status: Active Grant

• Current Assignee: Harman International Industries Incorporated (Samsung Electronics Co. Ltd.)
• Original Assignee: Harman International Industries Incorporated (Samsung Electronics Co. Ltd.)
• Inventors: Wood, Bradley C., Horton, Warren J.
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): Yacob, Sisay
• Application Number:
  US10/427,392
• Publication Number:
  US 20040217886A1
• Time in Patent Office: 1,231 Days
• Field of Search: 341/22, 341/33, 340/815.62, 307/119
• US Class Current: 341/33
• CPC Class Codes: G01D 5/24 by varying capacitance
• CPC Class Codes: H03K 17/962 Capacitive touch switches

Abstract

A capacitive touch switch system for use in an audio application includes a detecting circuit with a capacitive sensing device and a filtering circuit. The capacitive sensing device senses changes in capacitance. The filtering circuit filters external and/or internal interference that may affect the sensing of a capacitance change and/or the sound quality of an audio device. The capacitive touch switch system may be incorporated into a speaker and/or other components of the audio device. The capacitive touch switch system may control various audio parameters such as volume, bass, treble, balance, channel, and the like.

Claims

1. A capacitive touch switch system for an audio device, comprising:

a detecting circuit having a first conductive touch pad, a second conductive touch pad, a rectifier circuit coupled with the first conductive touch pad and the second conductive touch pad, a voltage doubler circuit coupled with the rectifier circuit, a single-pole high pass filter, a capacitive sensing device and a filter circuit, where the capacitive sensing device senses a change in capacitance at a location, where the filter circuit reduces interference from the capacitive sensing device; and

a transceiving circuit coupled to the detecting circuit, where the transceiving circuit transmits an output signal in response to an input signal from the detecting circuit, where the output signal controls at least one audio parameter.

2. The capacitive touch switch system of claim 1, where the interference affects sensing the change of capacitance.

3. The capacitive touch switch system of claim 1, where the interference affects sound quality.

4. The capacitive touch switch system of claim 1, where the interference is from fluorescent lighting.

5. The capacitive touch switch system of claim 1, where the interference is from a 120 Hz signal.

6. The capacitive touch switch system of claim 1, further comprising an oscillating circuit coupled to the detection circuit, where the detecting circuit is operable to attenuate a constant amplitude signal from the oscillating circuit.

7. The capacitive touch switch system of claim 6, where the oscillating circuit comprises two comparator circuits oppositely connected to each other.

8. The capacitive touch switch system of claim 7, where the oscillating circuit comprises resistive elements for controlling the feedback of the comparator circuits.

9. The capacitive touch switch system of claim 6, where the oscillating circuit generates a signal of approximately 150 kHz.

10. The capacitive touch switch system of claim 6, where the filter circuit comprises at least one filter to reduce interference with the constant amplitude signal.

11. The capacitive touch switch system of claim 1, where the single-pole high pass filter is optimized to filter 120 Hz signals.

12. The capacitive touch system of claim 1, where the transceiving system comprises:

at least one comparator circuit;

a feedback circuit coupled with the at least one comparator circuit; and

a voltage divider coupled with the at least one comparator circuit.

13. A capacitive touch switch system for an audio device, comprising:

an oscillating circuit having two comparator circuits operable to generate a constant amplitude signal, where the output of the first comparator circuit is electrically coupled to the input of the second comparator circuit;

a detecting circuit coupled to the oscillating circuit, the detecting circuit operable to filter internal and external interference, the detecting circuit having a first conductive touch pad, a second conductive touch pad, a rectifier circuit coupled with the first conductive touch pad and the second conductive touch pad, a voltage doubler circuit coupled with the rectifier circuit, and a high-pass filter;

a transceiving circuit coupled to the detecting circuit, the transceiving circuit operable to convert the constant amplitude signal into a logic signal, the transceiving circuit having at least one comparator circuit, a feedback circuit coupled with the at least one comparator circuit, and a voltage divider coupled with the at least one comparator circuit.

14. The capacitive touch switch system of claim 13 where the oscillating circuit generates a signal of approximately 150 kHz.

15. The capacitive touch switch system of claim 13 where the oscillating circuit further comprises resistive elements for controlling feedback of the comparator circuits.

16. The capacitive touch switch system of claim 13 where the high-pass filter of the detecting circuit is optimized to filter 120 Hz signals.

17. The capacitive touch switch system of claim 13 where the detecting circuit is operable to attenuate the constant amplitude signal generated by the oscillating circuit.

18. A capacitive touch switch system for an audio device, comprising:

a detecting circuit having a capacitive sensing device and a filter circuit, where the capacitive sensing device senses a change in capacitance at a location, where the filter circuit reduces interference from the capacitive sensing device, the detecting circuit further comprising a rectifier circuit coupled with the capacitive sensing device, a voltage doubler circuit coupled with the rectifier circuit, a single-pole high pass filter; and

a transceiving circuit coupled to the detecting circuit, where the transceiving circuit transmits an output signal in response to an input signal from the detecting circuit, where the output signal controls at least one audio parameter.

19. The capacitive touch switch system of claim 18, where the single-pole high pass filter is optimized to filter 120 Hz signals.