Touch stylus, touch detection method and touch detection system

• US 8,786,564 B2
• Filed: 03/23/2012
• Issued: 07/22/2014
• Est. Priority Date: 12/29/2011
• Status: Active Grant

• Current Assignee: FocalTech Systems Co.,Ltd
• Original Assignee: FocalTech Systems Co.,Ltd
• Inventors: Mo, Lianghua, Xu, Huaiyi, Tian, Jincheng, Dai, Huadong, Jiang, Xinxi, Li, Hua
• Primary Examiner(s): Karimi, Pegeman
• Application Number:
  US13/428,910
• Publication Number:
  US 20130169601A1
• Time in Patent Office: 851 Days
• Field of Search: 345/156, 345/173, 345/174, 345/179, 178 1801- 1806, 178/19.01
• US Class Current: 345/173
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
• CPC Class Codes: G06F 3/0383 Signal control means within the pointing device
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser

Abstract

The embodiments of the present invention disclose a touch stylus, a touch detection method and a touch detection system, which are suitable to be used for writing on a capacitive touch screen and can increase the success rate of touch. A method according to an embodiment of the present invention includes: receiving, by a sensing electrode, a square wave signal sent from a stylus tip of a touch stylus; performing a detection process on the square wave signal, by a sensing detection unit, the sensing detection unit having a clock synchronized with a clock of the touch stylus; determining, by a signal processing unit, whether a touch event occurs according to the square wave signal processed with the detection process; and calculating position coordinates of the touch event and reporting the position coordinates to a system control unit, by the signal processing unit, if a touch event occurs.

Claims

1. A touch stylus, comprising a stylus tip and a stylus body, wherein,

the stylus tip is connected to the stylus body, the stylus body is provided with a cavity in which a driving circuit board and a battery are arranged, the driving circuit board is electrically connected to the stylus tip, the battery is adapted to supply electrical energy to the driving circuit board, and the driving circuit board is adapted to generate a square wave signal and send the square wave signal to a touch detection system through the stylus tip, so that the touch detection system determines whether a touch event occurs according to the square wave signal;

wherein the touch stylus has a clock synchronized with a clock of a sensing detection unit of the touch detection system;

wherein the driving circuit board comprises a crystal oscillator, a first voltage boosting circuit, a second voltage boosting circuit, and a level converter, wherein

the first voltage boosting circuit is connected to the battery, the battery being adapted to supply electrical energy to the first voltage boosting circuit;

the first voltage boosting circuit is connected to the crystal oscillator, and adapted to supply electrical energy to the crystal oscillator;

the second voltage boosting circuit is connected to the first voltage boosting circuit and the level converter, and adapted to supply electrical energy for the level converter; and

the level converter is connected to the crystal oscillator, and adapted to perform level conversion on a square wave signal output by the crystal oscillator and send a result to the stylus tip.

2. The touch stylus according to claim 1, wherein the driving circuit board further comprises a pressure sensor, wherein the pressure sensor is connected to the level converter and adapted to collect a magnitude of the pressure in the touch detection system through the stylus tip and send the magnitude of the pressure to the level converter.

3. The touch stylus according to claim 1, further comprising a control switch, wherein the control switch is connected to the driving circuit board, and wherein the stylus tip sends the square wave signal to the touch detection system when the control switch is closed, and stops sending a square wave signal to the touch detection system when the control switch is open.

4. The touch stylus according to claim 1, further comprising an indicating device, wherein the indicating device is connected to the driving circuit board and adapted to indicate an operation status of the touch stylus.

5. A touch detection method, comprising:

receiving, by a sensing electrode, a square wave signal sent from a stylus tip of a touch stylus;

performing a detection process on the square wave signal, by a sensing detection unit, the sensing detection unit having a clock synchronized with a clock of the touch stylus;

determining, by a signal processing unit, whether a touch event occurs according to the square wave signal processed with the detection process; and

calculating position coordinates of the touch event and reporting the position coordinates to a system control unit, by the signal processing unit, if a touch event occurs;

wherein when the clock of the touch stylus is generated by a crystal oscillator, synchronization between the clock of the sensing detection unit and the clock of the touch stylus is performed by;

generating a clock and outputting the clock to a phase extraction control unit, by another crystal oscillator having a frequency that is the same as a frequency of the crystal oscillator, or a multiple of the frequency of the crystal oscillator, or a unit fraction of the frequency of the crystal oscillator;

extracting, by the phase extraction control unit, phase information of a signal sent from the touch stylus from the square wave signal received by the sensing electrode;

performing phase adjustment on the clock output by said another crystal oscillator to the phase extraction control unit, by the phase extraction control unit, according to the phase information; and

outputting, by the phase extraction control unit, the phase-adjusted clock to the sensing detection unit, wherein the sensing detection unit uses the phase-adjusted clock as its own clock.

6. The touch detection method according to claim 5, wherein synchronization between the clock of the sensing detection unit and the clock of the touch stylus is performed by:

performing frequency selection, by a band-pass filter, on the square wave signal;

amplifying, by an amplifier, the frequency-selected square wave signal; and

performing phase adjustment and frequency multiplication on the amplified square wave signal, and outputting a result to the sensing detection unit, by a phase-locked loop (PLL), wherein the sensing detection unit uses the result of frequency multiplication as the clock of the sensing detection unit.

7. A touch detection system, comprising a sensing electrode, a sensing detection unit, and a signal processing unit, wherein,

the sensing electrode is adapted to receive a square wave signal sent from a stylus tip of a touch stylus;

the sensing detection unit is adapted to perform a detection process on the square wave signal and send a result to the signal processing unit, the sensing detection unit having a clock synchronized with a clock of the touch stylus;

the signal processing unit is adapted to determine whether a touch event occurs according to the square wave signal processed with the detection process;

the signal processing unit is further adapted to calculate position coordinates of the touch event and report the position coordinates to a system control unit if a touch event occurs;

wherein when the clock of the touch stylus is generated by a crystal oscillator, the touch detection system further comprises;

another crystal oscillator, adapted to generate a clock and output the clock to a phase extraction control unit, wherein said another crystal oscillator has a frequency that is the same as a frequency of the crystal oscillator, or a multiple of the frequency of the crystal oscillator, or a unit fraction of the frequency of the crystal oscillator; and

the phase extraction control unit, adapted to extract phase information of the touch stylus from the square wave signal received by the sensing electrode,

wherein the phase extraction control unit is further adapted to perform, according to the phase information, phase adjustment on the clock output by said another crystal oscillator to the phase extraction control unit; and

the phase extraction control unit is further adapted to output the phase-adjusted clock to the sensing detection unit, wherein the sensing detection unit uses the phase-adjusted clock as its own clock.

8. The touch detection system according to claim 7, wherein the sensing electrode comprises a first electrode, a second electrode and a multiplexer, wherein,

the first electrode is adapted to receive the square wave signal sent from the stylus tip of the touch stylus;

the second electrode is adapted to receive the square wave signal sent from the stylus tip of the touch stylus; and

the multiplexer is adapted to send each of the square wave signal received by the first electrode and the square wave signal received by the second electrode to the sensing detection unit.

9. The touch detection system according to claim 8, wherein:

the first electrode is further adapted to send a square wave signal to the second electrode;

the second electrode is further adapted to receive the square wave signal sent from the first electrode; and

the multiplexer is further adapted to send the square wave signal received by the second electrode to the sensing detection unit.

10. The touch detection system according to claim 7, further comprising:

a band-pass filter, adapted to perform frequency selection on the square wave signal;

an amplifier, adapted to amplify the frequency-selected square wave signal; and

a phase-locked loop (PLL), adapted to perform phase adjustment and frequency multiplication on the amplified square wave signal, and output a result to the sensing detection unit, wherein the sensing detection unit uses the result of frequency multiplication as the clock of the sensing detection unit.