CONTROL METHOD AND ELECTRONIC STYLUS FOR TOUCH INPUT TO A CAPACITIVE TOUCHPAD MODULE

• US 20140035870A1
• Filed: 09/09/2013
• Published: 02/06/2014
• Est. Priority Date: 01/06/2009
• Status: Abandoned Application

• Current Assignee: Elan Microelectronics Corporation
• Original Assignee: Elan Microelectronics Corporation
• Inventors: YEH, I-Hau, WANG, Tsun-Min, HUANG, Chun-Chung, YEH, Chi-Tein, CHENG, Chung-Han, HUANG, Hung-Ming
• Application Number:
  US14/021,676
• Publication Number:
  US 20140035870A1
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/0441 using active external devices, e.g. active pens, for receiving changes in electrical potential transmitted by the digitiser, e.g. tablet driving signals
• 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
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

An electronic stylus emits an excitation signal to apply to a trace of a capacitive touchpad module near a touch point when the electronic stylus touches the capacitive touchpad module, so as to change a waveform of a charging/discharging signal in the trace, and depending on the waveform variation, the capacitive touchpad module can identify the touch point.

Claims

1. A control method for an apparatus including an electronic stylus and a capacitive touchpad module for touch input, the control method comprising the steps of:

(A) generating an excitation signal having a constant phase difference from a charging/discharging signal in a trace of the capacitive touchpad module;

(B) supplying the excitation signal to a tip of the electronic stylus;

(C) emitting the excitation signal by the tip to apply to the trace of the capacitive touchpad module near a touch point when the tip touches the capacitive touchpad module, so as to change a waveform of the charging/discharging signal in the trace; and

(D) sensing the touch point according to an amplitude of the waveform.

2. The control method of claim 1, wherein the step A comprises the step of setting a frequency of the excitation signal equal to an integral multiple of a frequency of the charging/discharging signal.

3. The control method of claim 1, wherein the step A comprises the step of setting a frequency of the excitation signal equal to a frequency of the charging/discharging signal and a duty ratio of the excitation signal equal to 50%.

4. The control method of claim 1, wherein the step A comprises the step of operating an oscillation circuit to generate the excitation signal.

5. The control method of claim 1, wherein the step A comprises the steps of:

detecting the charging/discharging signal from the trace to generate a detection signal;

up-converting the detection signal to generate a high-frequency signal;

transmitting the high-frequency signal to the electronic stylus; and

receiving and down-converting the high-frequency signal to generate the excitation signal.

6. The control method of claim 1, wherein the step A comprises the steps of:

detecting the charging/discharging signal from the trace to generate a detection signal;

modulating the detection signal to generate a modulated carrier signal;

transmitting the modulated carrier signal to the electronic stylus; and

receiving and demodulating the modulated carrier signal to generate the excitation signal.

7. The control method of claim 1, wherein the step B comprises the steps of:

detecting the charging/discharging signal from the trace to generate a detection signal which is related to a phase and a frequency of the charging/discharging signal;

embedding data representing the detection signal into a carrier signal;

transmitting the carrier signal to the electronic stylus;

extracting the data from the carrier signal; and

generating the excitation signal according to the extracted data.

8. An electronic stylus for touch input to a capacitive touchpad module, comprising:

an oscillation circuit generating an excitation signal having a constant phase difference from the charging/discharging signal;

a power circuit connected to the oscillation circuit, providing a supply voltage for the oscillation circuit; and

a tip connected to the oscillation circuit, emitting the excitation signal to apply to a trace of the capacitive touchpad module near a touch point when the electronic stylus touches the capacitive touchpad module, so as to change a waveform of a charging/discharging signal in the trace.

9. The electronic stylus of claim 8, wherein the oscillation circuit comprises:

a boost circuit connected to the power circuit, boosting the supply voltage to generate a boosted voltage; and

a quartz oscillator connected to the boost circuit, driven by the boosted voltage to generate the excitation signal.

10. The electronic stylus of claim 8, wherein the power circuit generates the supply voltage according to a radio frequency signal transmitted from the capacitive touchpad module.

11. The electronic stylus of claim 8, wherein the power circuit transforms a magnetic force into the supply voltage.

12. The electronic stylus of claim 8, wherein the power circuit comprises a battery providing the supply voltage.

13. The electronic stylus of claim 8, further comprising a switch being turned on or off to control whether or not to emit the excitation signal.

14. The electronic stylus of claim 8, wherein the tip comprises a metal.

15. The electronic stylus of claim 8, wherein the tip comprises a flexible conductor.

16. The electronic stylus of claim 8, wherein the tip comprises a metal wrapped by a nonconductor.

17. The electronic stylus of claim 8, further comprising:

a metal wrapping around the tip;

a first insulator wrapping around the metal for shielding against ambient interference; and

a second insulator between the tip and the metal for separating the tip from the metal.

18. The electronic stylus of claim 8, wherein the excitation signal has a frequency equal to an integral multiple of a frequency of the charging/discharging signal.

19. The electronic stylus of claim 8, wherein the excitation signal has a frequency equal to a frequency of the charging/discharging signal and a duty ratio of 50%.