TOUCH SENSING APPARATUS

• US 20070035312A1
• Filed: 05/23/2006
• Published: 02/15/2007
• Est. Priority Date: 08/12/2005
• Status: Active Grant

• Current Assignee: Hong Fu Jin Precision Industry (Shenzhen) Co., Ltd. (Hon Hai Precision Industry Co., Ltd.), Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hong Fu Jin Precision Industry (Shenzhen) Co., Ltd. (Hon Hai Precision Industry Co., Ltd.), Hon Hai Precision Industry Co., Ltd.
• Inventors: Hsieh, Kuan-Hong, Chung, Shin-Hong, Wang, Han-Che, Lin, Shi-Quan
• Granted Patent: US 7,170,301 B1
• Time in Patent Office: Days
• US Class Current: 324/658
• CPC Class Codes: H03K 17/962 Capacitive touch switches

Abstract

A touch sensing apparatus includes a signal source for generating an alternating current signal, a conductor connected to the signal source, a sensor for receiving a noise generated by a contact of an object. The sensor together with the conductor form a simulated capacitor that results in alternating current signal flowing through the sensor when the sensor is contacted by the object. A detector has a first input end and a second input end. The detector results in voltage differences between the first and second input ends thereof when receiving the alternating current signal output from the sensor, and thus output a signal. A rectifying circuit is used for rectifying the alternating current signal generated by the signal source and simultaneously generating a noise. One end of the rectifier circuit is connected to the signal source and other end of the rectifier circuit is connected to the second input end of the detector.

Claims

1. A touch sensing apparatus comprising:

a signal source for generating an alternating current signal;

a conductor connected to the signal source;

a sensor for receiving a noise generated by a contact of an object;

wherein the sensor and the conductor form a simulated capacitor that results in alternating current signal flowing through the sensor when the sensor is contacted by the object;

a detector having a first input end and a second input end, the detector upon receiving the alternating current signal output from the sensor resulting in voltage differences between the first and second input ends thereof, and outputting a signal; and

a rectifying circuit for rectifying the alternating current signal generated by the signal source and simultaneously generating a noise;

wherein one end of the rectifier circuit is connected to the signal source and the other end of the rectifier circuit is connected to the second input end of the detector.

2. The touch sensing apparatus as described in claim 1, further comprising a direct current power source, wherein the direct current power source is electrically connected to the second input end and a positive power input end of the detector, and provides a bias voltage for the detector.

3. The touch sensing apparatus as described in claim 2, further comprising a resistance element connected between the first input end and the second input end of the detector.

4. The touch sensing apparatus as described in claim 1, further comprising a microcontroller unit (MCU) for processing the signal outputted by the detector.

5. The touch sensing apparatus as described in claim 1, wherein the detector comprises a relatively high input impedance.