Touch sensing apparatus using varying signal delay input to a flip-flop

• US 7,667,693 B2
• Filed: 11/09/2006
• Issued: 02/23/2010
• Est. Priority Date: 11/11/2005
• Status: Expired due to Fees

• Current Assignee: Gold Charm Limited (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: Chung, Shin-Hong, Hsieh, Kuan-Hong, Wang, Han-Che
• Primary Examiner(s): Mengista, Amare
• Assistant Examiner(s): Lee, Gene W
• Application Number:
  US11/558,421
• Publication Number:
  US 20070108994A1
• Time in Patent Office: 1,202 Days
• Field of Search: 345/173, 178/18.01, 178 1802- 1804, 178/18.05, 178/18.06, 178/18.07, 178/20.04, 324/663, 324/415, 200/600
• US Class Current: 345/173
• CPC Class Codes: H03K 17/962 Capacitive touch switches

Abstract

A touch sensing apparatus is provided. The apparatus includes: a flip-flop, a sensor, an AC signal and a detector. The AC signal supplies AC signals to the flip-flop. The flip-flop outputs a first type output signal at the output thereof when the sensor is not touched. The sensor receives electricity signals from an 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 causes the flip-flop to output a second type output signal at the output thereof. The detector detects a change from the first type output signal to the second type output signal at the output of the flip-flop and accordingly identifies a touch on the sensor.

Claims

1. A touch sensing apparatus comprising:

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

an alternating current (AC) signal source for supplying AC signals to the first input and the second input of the flip-flop;

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

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

a resistor interposed between AC signal source and the first input of the flip-flop; and

a detector electrically connected to the output of the flip-flop and for detecting a change at the output of the flip-flop;

wherein the flip-flop outputs a first type output signal at the output thereof when the sensor is not 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 detector detects a change from the first type output signal to the second type output signal at the output of the flip-flop and accordingly identifies a touch on the sensor.

2. The touch sensing apparatus as described in claim 1, wherein the AC signals are generated in phase and at a same frequency, and are inputted to the first input and the second input of the flip-flop simultaneously.

3. The touch sensing apparatus as described in claim 1, wherein the AC signals are generated out of phase and at a same frequency and inputted to the first input and second input of the flip-flop simultaneously.

4. The touch sensing apparatus as described in claim 1, further comprising a microcontroller unit (MCU) for executing a predetermined task after the detector identifies the touch on the sensor.

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

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

7. The touch sensing apparatus as described in claim 6, further comprising two conductors respectively connected to the positive signal output and the negative signal output of the differential signal source.

8. The touch sensing apparatus as described in claim 7, wherein the sensor locates between the two conductors and forms two simulated capacitors with the two conductors for offsetting environmental noise.

9. The touch sensing apparatus as described in claim 6, wherein the differential signal source is further provided for providing an alternating magnetic field for the touch sensing apparatus.