Capacitance touch sensor

• US 8,665,224 B2
• Filed: 04/14/2008
• Issued: 03/04/2014
• Est. Priority Date: 04/13/2007
• Status: Active Grant

• Current Assignee: Generalplus Technology Inc.
• Original Assignee: Generalplus Technology Inc.
• Inventors: Liao, Tung-Tsai, Lo, Li Sheng, Yang, Chih Hsiang
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): CRAWLEY, KEITH L
• Application Number:
  US12/102,553
• Publication Number:
  US 20080251299A1
• Time in Patent Office: 2,150 Days
• Field of Search: 345173-178, 341/20, 341/33, 341/658, 341/663
• US Class Current: 345/173
• 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 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 each of sensor panels comprises a first metal and a second metal, wherein the first metal is coupled to the square wave generator for receiving the square wave clock and the second metal is coupled to a common voltage, 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, wherein the sensor panels exclude any active component;

M peak detectors for respectively receiving output signals of the M rows of sensor panels and generating analog peak signals, wherein the i^th peak detector corresponds to sensor panels at the i^th row, and the i^th peak detector comprises;

N diodes, each of the N diodes having a P pole and a N pole, wherein the P pole of the j^th diode of the i^th peak detector is directly connected to the first metal of the corresponding sensor panel at the i^th row and the j^th column, and the N poles are connected together, wherein i and j are natural numbers, i is smaller than or equal to M, and j is smaller than or equal to N;

a resistor having a first terminal, which is directly 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;

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; and

wherein there is no amplifier between the sensor panels and the peak detectors.

2. The capacitance touch sensor according to claim 1, wherein each of the sensor panels comprises:

a resistor having a first terminal for receiving the square wave clock; and

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

3. The capacitance touch sensor according to claim 1, wherein the control unit sequentially enables the N control signals so that the 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.