TOUCH SENSING APPARATUS

• US 20070124632A1
• Filed: 11/08/2006
• Published: 05/31/2007
• Est. Priority Date: 11/10/2005
• Status: Active Grant

• Current Assignee: Gold Charm Limited (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: Hsieh, Kuan-Hong, Chung, Shin-Hong, Wang, Han-Che
• Granted Patent: US 7,683,892 B2
• Time in Patent Office: Days
• US Class Current: 714/724
• CPC Class Codes: H03K 17/962 Capacitive 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

Abstract

A touch sensing apparatus is provided. The apparatus includes a sensor (13), a flip-flop (16), and a microcontroller unit (17). The sensor is connected to one of input of the flip-flop for receiving electricity signals from an object that touches the sensor. The MCU respectively supplies two AC signals at two outputs thereof to two inputs of the flip-flop. The flip-flop outputs a first type output signal at the output thereof when the sensor not being touched. When being touched, the sensor receives electricity signals from an object, and causes a delay of an AC signal to be inputted to the input of the flip-flop to which the sensor is connected, the delay of the AC signal to be inputted to the input of the flip-flop further causes the flip-flop to output a second type output signal at a output thereof. The MCU detects a change of the output signals of the flip-flop from the first type output signal to the second type output signal and accordingly identifies a touch on the sensor.

Claims

1. A touch sensing apparatus comprising:

a flip-flop having a first input and a second input and an output;

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

a microcontroller unit (MCU) having an input, a first output and a second output, the input for receiving and providing output signals of the flip-flop to the MCU to identify a touch on the sensor according to the output signals of the flip-flop, the first output for outputting a first AC signal to the first input of the flip-flop, and the second output for outputting a second AC signal to the second input of the flip-flop;

an integration circuit interposed between the second input of the flip-flop and the second output of the MCU and for delaying the AC signal to be inputted to the second input of the flip-flop; and

a resistor interposed between the first input of the flip-flop and the first output of the MCU;

wherein;

the flip-flop outputs a first type output signal at the output thereof when the sensor not being touched;

the sensor receives electricity signals from the object, and causes a delay of the AC signal to be inputted to the first input of the flip-flop, the delay of the AC signal to be inputted to the first input of the flip-flop further causing the flip-flop to output a second type output signal at the output thereof; and

the MCU detects an output change of the output signals of the flip-flop from the first type output signal to the second type output signal and accordingly identifies a touch on the sensor.

2. The touch sensing apparatus as described in claim 1, wherein the MCU is further provided for executing a predetermined task upon identifying the touch on the sensor.

3. The touch sensing apparatus as described in claim 1, wherein the flip-flop is a D-type flip-flop.

4. The touch sensing apparatus as described in claim 1, further comprising a differential signal source configured for generating a positive signal and a negative signal.

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

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

7. The touch sensing apparatus as described in claim 4, wherein the differential signal source is further provided for providing an alternating magnetic field for the touch sensing apparatus.