TOUCH SENSING APPARATUS

• US 20070084644A1
• Filed: 10/09/2006
• Published: 04/19/2007
• Est. Priority Date: 10/14/2005
• Status: Abandoned Application

• Current Assignee: Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: Hsieh, Kuan-Hong, Chung, Shin-Hong, Wang, Han-Che
• Application Number:
  US11/309,833
• Publication Number:
  US 20070084644A1
• Time in Patent Office: Days
• US Class Current: 178/18.60
• CPC Class Codes: G01D 5/00 Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable G01D3/00 takes precedence; specially adapted for apparatus giving results other than momentary value of variable G01D1/00
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 17/9645 Resistive touch switches
• CPC Class Codes: H03K 2217/96072 Phase comparison, i.e. where a phase comparator receives at one input the signal directly from the oscillator, at a second input the same signal but delayed, with a delay depending on a sensing capacitance
• CPC Class Codes: H03K 2217/96073 Amplitude comparison

Abstract

A preferred embodiment of a touch sensing apparatus includes an amplifier, an alternating current (AC) signal source, a sensor, a detector, a first load circuit, and a second load circuit. The alternating current (AC) signal source is for outputting AC signals to a first input and a second input of the amplifier. The sensor is for receiving electricity signals from an object that touches the sensor. The detector is for identifying a touch on the sensor according to output of the amplifier. The sensor and the first load circuit and the second load circuit, enable the amplifier has a common mode (CM) input when the sensor is not touched by the object. The sensor receives electricity signals from the object and enables the amplifier has a differential mode input. The amplifier amplifies a difference between the first input and the second input thereof and outputting the amplified difference to the detector.

Claims

1. A touch sensing apparatus comprising:

an amplifier having a first input and a second input;

an alternating current (AC) signal source for outputting AC signals to the first input and the second input of the amplifier;

a sensor connected to the first input of the amplifier and for receiving electricity signals from an object that touches the sensor;

a detector for identifying a touch on the sensor according to output of the amplifier;

a first load circuit connected between the AC signal source and the first input of the amplifier; and

a second load circuit connected between the AC signal source and the second input of the amplifier;

wherein;

the sensor and the first load circuit and the second load circuit, enable the amplifier has a common mode (CM) input when the sensor is not touched by the object;

the sensor receives electricity signals from the object and enables the amplifier to have a differential mode input; and

the amplifier amplifies a difference between the first input and the second input thereof and outputting the amplified difference to the detector.

2. The touch sensing apparatus as described in claim 1, further comprising a microcontroller unit (MCU) connected to the detector and for performing a procedure corresponding to the touch of the object on the sensor.

3. The touch sensing apparatus as described in claim 1, further comprising a differential signal source with a positive output and a negative output, the differential signal source providing an alternating magnetic field for the touch sensing apparatus.

4. The touch sensing apparatus as described in claim 3, further comprising two conductors respectively connected to the positive output and the negative output of the differential signal source.

5. The touch sensing apparatus as described in claim 4, wherein the sensor is located between the two conductors and forms two simulated capacitors respectively with the two conductors for offsetting environmental noise.