Method of detecting touch and apparatus for detecting touch using the same

• US 9,274,663 B2
• Filed: 04/23/2014
• Issued: 03/01/2016
• Est. Priority Date: 04/25/2013
• Status: Active Grant

• Current Assignee: AnaPass, Inc.
• Original Assignee: AnaPass, Inc.
• Inventors: Lee, Jong Hwa, Song, Ha Sun, Seo, Woo Hyoung, Park, Joon Bae
• Primary Examiner(s): Cheng, Joe H
• Application Number:
  US14/259,248
• Publication Number:
  US 20140320449A1
• Time in Patent Office: 678 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• 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

Disclosed are an apparatus for detecting touch and a method for detecting touch with reduced effect of noise. The apparatus includes a signal source configured to generate a variable frequency signal changed from a starting frequency to an ending frequency, a touch panel including a plurality of driving electrodes and a plurality of sensing electrodes, wherein the variable phase signal is applied to one of the plurality of driving electrodes, and the sensing electrode outputs a touch signal that is modulated by the variable frequency signal, a demodulation unit configured to demodulate the touch signal using the variable frequency signal, and an accumulation unit configured to accumulate the demodulated touch signal to detect the touch.

Claims

1. An apparatus for detecting touch comprising:

a signal source configured to generate a variable frequency signal changed from a starting frequency to an ending frequency;

a touch panel including a plurality of driving electrodes and a plurality of sensing electrodes, wherein the variable frequency signal is applied to one of the plurality of driving electrodes, and the sensing electrode outputs a touch signal that is modulated by the variable frequency signal;

a demodulation unit configured to demodulate the touch signal using the variable frequency signal; and

an accumulation unit configured to accumulate the demodulated touch signal to detect the touch,

wherein a frequency of the variable frequency signal is increased or reduced from the starting frequency to the ending frequency.

2. The apparatus of claim 1, further comprising:

a delay compensator unit configured to receive the variable frequency signal from the signal source, and output delayed variable frequency signal to the demodulation unit, wherein the delayed variable frequency signal has a phase corresponding to a phase of the variable frequency signal used in modulating the touch signal.

3. The apparatus of claim 1, wherein the apparatus further includes a signal conversion unit configured to receive the touch signal to convert the received signal into a voltage signal.

4. The apparatus of claim 3, wherein the accumulation unit includes an integrator.

5. The apparatus of claim 3, wherein the signal conversion unit includes an operational amplifier including an output terminal, an inverting input terminal electrically connected to the touch panel, and a non-inverting input terminal electrically connected to a ground potential, and a charge amplifier to which resistance and a capacitor are electrically connected on a path fed back from the output terminal of the operational amplifier to the inverting input terminal.

6. The apparatus of claim 1, wherein the frequency of the variable frequency signal is linearly increased or reduced from the starting frequency to the ending frequency.

7. The apparatus of claim 1, wherein the frequency of the variable frequency signal is non-linearly increased or reduced from the starting frequency to the ending frequency.

8. The apparatus of claim 1, wherein the signal generated by the signal source is any one of a step wave, a rectangular pulse, a sinusoidal pulse, a triangular pulse, and a linear superposition thereof.

9. The apparatus of claim 1, wherein the signal source includes a frequency spreader configured to form the variable frequency signal and a transmitter unit configured to transmit the variable frequency signal output from the frequency spreader.

10. The apparatus of claim 1, wherein the frequency of the variable frequency signal is changed per a phase change of 180×

n°

of the variable frequency signal (n being a natural number).

11. A method of detecting touch comprising:

generating a variable frequency signal changed from a starting frequency to an ending frequency, by forming a signal in which a frequency of the variable frequency signal is increased or reduced from the starting frequency to the ending frequency;

outputting a touch signal modulated by the variable frequency signal in such a manner that the variable frequency signal is applied to any one of driving electrodes and a sensing electrode detects touch by an object;

demodulating the touch signal using the variable frequency signal; and

accumulating the demodulated signal.

12. The method of claim 11, wherein the demodulating the touch signal using the variable frequency signal further includes converting the touch signal into a voltage signal.

13. The method of claim 12, wherein the converting of the touch signal into a voltage signal includes receiving the touch signal to convert the received signal into the voltage signal using an operational amplifier including an operational amplifier including an output terminal, an inverting input terminal electrically connected to the touch panel, and a non-inverting input terminal electrically connected to a ground potential, and a charge amplifier to which resistance and a capacitor are electrically connected on a path fed back from the output terminal of the operational amplifier to the inverting input terminal.

14. The method of claim 11, wherein the demodulating the touch signal includes demodulating the touch signal using a variable frequency signal delayed to have same phase with the variable frequency signal used in modulating the touch signal.

15. The method of claim 11, wherein the accumulating of the demodulated signal includes accumulating the demodulated signal using an integrator.

16. The method of claim 11, wherein the frequency of the variable frequency signal is linearly increased or reduced from the starting frequency to the ending frequency.

17. The method of claim 11, wherein the frequency of the variable frequency signal is non-linearly increased or reduced from the starting frequency to the ending frequency.

18. The method of claim 11, the signal formed in the generating of the variable frequency signal has a rectangular pulse whose frequency is changed.

19. The method of claim 11, wherein the generating of the variable frequency signal includes changing the frequency of the variable frequency signal per a phase change of 180×

n°

of the variable frequency signal (n being a natural number).