CAPACITANCE TOUCH SENSOR

• US 20080251299A1
• Filed: 04/14/2008
• Published: 10/16/2008
• Est. Priority Date: 04/13/2007
• Status: Active Grant

• Current Assignee: Generalplus Technology Inc.
• Original Assignee: Generalplus Technology Inc.
• Inventors: Lo, Li Sheng, LIAO, Tung-Tsai, Yang, Chih Hsiang
• Granted Patent: US 8,665,224 B2
• Time in Patent Office: Days
• US Class Current: 178/18.06
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2217/96073 Amplitude comparison

Abstract

A capacitance touch sensor includes a square wave generator for generating a square wave clock, a sensor panel for receiving the square wave clock and then generating a panel signal, a peak detector for receiving the panel signal and then generating an analog peak signal, an analog-to-digital converter for receiving the analog peak signal and then generating a digital peak signal, and a control unit for receiving the digital peak signal and generating a detection signal according to a level of the digital peak signal to indicate whether the sensor panel is touched or not.

Claims

1. A capacitance touch sensor, comprising:

a square wave generator, for generating a high-frequency square wave clock;

a sensor panel, for receiving the high-frequency square wave clock and thus generating a panel signal;

a peak detector, for receiving the panel signal and thus generating an analog peak signal;

an analog-to-digital converter, for receiving the analog peak signal and thus generating a digital peak signal; and

a control unit, for generating a detection signal to judge whether the sensor panel is touched or not according to the digital peak signal.

2. The capacitance touch sensor according to claim 1, wherein the sensor panel comprises:

a resistor, having a first terminal for receiving the high-frequency square wave clock; and

a panel, capacitor having a first terminal, which is connected to a second terminal of the resistor and generates the panel signal, and a second terminal grounded.

3. The capacitance touch sensor according to claim 1, wherein the peak detector comprises:

a resistor, having a first terminal, which receives the panel signal and generates the analog peak signal, and a second terminal grounded; and

a capacitor, connected to the resistor in parallel.

4. The capacitance touch sensor according to claim 3, wherein the peak detector further comprises:

a diode, having a P pole connected to the sensor panel and an N pole connected to the resistor.

5. A capacitance touch sensor, comprising:

a square wave generator, for generating a high-frequency square wave clock;

N buffers, respectively controlled by N control signals, wherein only one of the N control signals is enabled at the same time, and N is an integer greater than 1;

a plurality of sensor panels, which constitutes architecture of a matrix having N columns and M rows, wherein input terminals of each of the columns of the sensor panels are respectively connected to an output terminal of one of the N buffers, and M is an integer greater than 1;

M peak detectors, for respectively receiving output signals of the M rows of sensor panels and generating analog peak signals;

M analog-to-digital converters, for respectively receiving the analog peak signals of the M peak detectors and generating digital peak signals; and

a control unit, for sequentially receiving the digital peak signals of the M analog-to-digital converters and respectively generating a plurality of detection signals according to the digital peak signals to judge whether the plurality of sensor panels is touched or not,

wherein the control unit further generates the N control signals.

6. The capacitance touch sensor according to claim 5, wherein each of the sensor panels comprises:

a resistor, having a first terminal for receiving the high-frequency square wave clock; and

a panel capacitor, having a first terminal connected to a second terminal of the resistor, and a second terminal grounded.

7. The capacitance touch sensor according to claim 6, wherein each of the peak detectors further comprises:

N diodes, each of the N diodes having a P pole and a N pole, wherein the P poles are respectively connected to output terminals of the sensor panels, and the N poles are connected together;

a resistor, having a first terminal, which is connected to the N poles of the N diodes and generates the analog peak signal, and a second terminal grounded; and

a capacitor, connected to the resistor in parallel.

8. The capacitance touch sensor according to claim 7, wherein the control unit sequentially enables the N control signals so that the high-frequency square wave clock is sequentially inputted to the corresponding M sensor panels, while the control unit receives the digital peak signals of the M analog-to-digital converters and generates the plurality of detection signals according to the digital peak signals to judge whether the sensor panels are touched or not.