Capacitive touch detecting device and method using level shift, and display device using the same

• US 9,703,425 B2
• Filed: 09/01/2011
• Issued: 07/11/2017
• Est. Priority Date: 09/01/2010
• Status: Active Grant

• Current Assignee: G2touch Co Ltd
• Original Assignee: G2touch Co Ltd
• Inventors: Lee, Sung Ho
• Primary Examiner(s): Shankar, Vijay
• Assistant Examiner(s): Sarma, Abhishek
• Application Number:
  US13/820,146
• Publication Number:
  US 20130162595A1
• Time in Patent Office: 2,140 Days
• Field of Search: 345173-174
• 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 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• 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

Abstract

Provided is a touch detecting device that detects occurrence of a level shift phenomenon of a voltage variation to thus acquire a touch signal, when a touch capacitance due to a touch input is added to a common electrode capacitance formed between a common electrode and a sensor pattern. Accordingly, the touch signal may be stably obtained in spite of external noise, and an influence due to a parasitic capacitance may be minimized.

Claims

1. A capacitive touch detecting device for detecting occurrence of a touch capacitance (Ct) by an approach of a bodily finger or a touch input instrument such as a conductor similar to the bodily finger, the capacitive touch detecting device comprising:

a plurality of sensor patterns, each of the sensor patterns forming the touch capacitance (Ct) between the touch input instrument and the sensor pattern when a touch input occurs, wherein the sensor patterns are formed on the substrate and are formed of a transparent conductor;

a common electrode that forms a common electrode capacitance (Cvcom) between each of the sensor patterns and the common electrode;

a charging unit that supplies a charge signal to each of the sensor patterns to thus accumulate charges in the common electrode capacitance (Cvcom); and

a level shift detecting unit that detects a level shift that occurs in a voltage variation in the sensor pattern at the time of occurrence of the touch input, with respect to another voltage variation in the sensor pattern at the time of non-occurrence of the touch input, to thereby acquire a touch signal,

wherein the common electrode has a common voltage (Vcom) level that alternates at a predetermined frequency,

wherein the level shift detecting unit detects a level shift between the voltage variations arising from the sensor pattern by the common voltage (Vcom) before and after the occurrence of the touch input, and

wherein the sensor patterns are grouped and connected with the charging unit and the level shift detecting unit through a multiplexer, and signals from the sensor patterns within the group are multiplexed by the multiplexer and thus the signal from each of the sensor patterns is individually processed.

2. The capacitive touch detecting device according to claim 1, wherein the voltage variation at the time of non-occurrence of the touch input is determined by following Equation 1,

wherein the voltage variation at the time of addition of the touch capacitance (Ct) is determined by following Equation 2, and

wherein the level shift uses a difference between the voltage variations of the following Equations 1 and 2,

3. The capacitive touch detecting device according to claim 1, wherein the level shift detecting unit detects the level shift in the sensor pattern at the rising time and/or falling time of the common voltage level.

4. The capacitive touch detecting device according to claim 1, wherein the level shift detecting unit detects a touch share of the touch input instrument with respect to the sensor pattern on the basis of size of the level shift.

5. The capacitive touch detecting device according to claim 1, wherein the level shift detecting unit comprises an amplifier to amplify the signal from the sensor pattern.

6. The capacitive touch detecting device according to claim 5, wherein the amplifier is a differential amplifier to differentially amplify the signal from the sensor pattern.

7. The capacitive touch detecting device according to claim 5, wherein the amplifier has a high-impedance state input thereby isolating the charges charged in the common electrode capacitance (Cvcom) when the charging unit is turned off.

8. The capacitive touch detecting device according to claim 1, wherein the common electrode is a common electrode of a display device on which the touch detecting device has been mounted, and

wherein the capacitive touch detecting device further comprises a common voltage receiving unit that receives common voltage information of the common electrode from the display device.

9. The capacitive touch detecting device according to claim 1, further comprising a common voltage supply unit that applies the common voltage to the common electrode.

21. The capacitive touch detecting device according to claim 1, further comprising an air gap between the capacitive touch detecting device and a display device.

10. A capacitive touch detecting method for detecting occurrence of a touch capacitance (Ct) by an approach of a touch input instrument to a sensor pattern of a plurality of sensor patterns, wherein the sensor patterns are formed of a transparent conductor, the capacitive touch detecting method comprising the steps of:

supplying, by a charging unit, a charging signal to each of the sensor patterns and a common electrode capacitance (Cvcom) formed between each of the sensor patterns and a common electrode, a common voltage (Vcom) being applied to the common electrode;

interrupting, by the charging unit, the supply of the charging signal to thereby isolate the charges of the charging signal;

detecting, by a level shift detecting unit, a voltage variation in the sensor pattern at the time of occurrence of a touch input; and

detecting, by the level shift detecting unit, a level shift between the voltage variations before and after the occurrence of the touch input,

wherein the charging unit supplies the charge signal to each of the sensor patterns to thus accumulate charges in the common electrode capacitance (Cvcom), and

wherein the sensor patterns are grouped and connected with the charging unit and the level shift detecting unit through a multiplexer, and signals from the sensor patterns within the group are multiplexed by the multiplexer and thus the signal from each of the sensor patterns is individually processed.

11. The capacitive touch detecting method of claim 10, wherein the voltage variation at the time of non-occurrence of the touch input is determined by following Equation 1,

wherein the voltage variation at the time of addition of the touch capacitance (Ct) is determined by following Equation 2, and

wherein the level shift uses a difference between the voltage variations of the following Equations 1 and 2,

12. The capacitive touch detecting method of claim 10, wherein the common voltage (Vcom) has a level that alternates at a predetermined frequency, and

wherein the level shift is detected at the rising time and/or falling time of the common voltage level.

13. The capacitive touch detecting method of claim 10, further comprising a step of detecting a touch share of the touch input instrument with respect to the sensor pattern on the basis of size of the level shift.

14. The capacitive touch detecting method of claim 10, further comprising a step of differentially amplifying the signal from the sensor pattern.

15. The capacitive touch detecting method of claim 14, wherein a differential input signal is the voltage variation at the time of the non-occurrence of the touch input, at the differential amplifying step.

16. The capacitive touch detecting method of claim 15, further comprising a step of storing the voltage variation at the time of the non-occurrence of the touch input in a memory with respect to the sensor pattern.

22. The capacitive touch detecting method of claim 10, further comprising a step of forming an air gap between the capacitive touch detecting device and a display device.

17. A display device having a built-in capacitive touch detecting device for detecting occurrence of a touch capacitance (Ct) by an approach of a bodily finger or a touch input instrument such as a conductor similar to the bodily finger, wherein the capacitive touch detecting device comprises:

a plurality of sensor patterns, each of the sensor patterns forming the touch capacitance (Ct) between the touch input instrument and the sensor pattern when a touch input occurs, each of the sensor patterns being disposed at a distance spaced from a common electrode to thus form a common electrode capacitance (Cvcom), wherein the sensor patterns are formed of a transparent conductor;

a charging unit that supplies a charge signal to each of the sensor patterns to thus accumulate charges in the common electrode capacitance (Cvcom);

a level shift detecting unit that detects a level shift that occurs in a voltage variation in the sensor pattern at the time of occurrence of the touch input, with respect to another voltage variation in the sensor pattern at the time of non-occurrence of the touch input, to thereby acquire a touch signal,

wherein the common electrode has a common voltage (Vcom) level that alternates at a predetermined frequency,

wherein the level shift detecting unit detects a level shift between the voltage variations arising from the sensor pattern by the common voltage (Vcom) before and after the occurrence of the touch input,

wherein the level shift detecting unit detects the level shift in the sensor pattern at a rising time and a falling time of the common voltage level, and

wherein the sensor patterns are grouped and connected with the charging unit and the level shift detecting unit through a multiplexer, and signals from the sensor patterns within the group are multiplexed by the multiplexer and thus the signal from each of the sensor patterns is individually processed.

18. The display device according to claim 17, further comprising a common voltage receiving unit that receives common voltage information of the common electrode.

19. The display device according to claim 17, further comprising a common voltage detecting unit that detects a common voltage level of the common electrode.

20. The display device according to claim 17, wherein the charging unit and the level shift detecting unit are provided in an invisible region.