Touch sensor, display and electronic device using a timing control signal

• US 9,927,925 B2
• Filed: 05/26/2010
• Issued: 03/27/2018
• Est. Priority Date: 05/29/2009
• Status: Active Grant

• Current Assignee: Japan Display Incorporated
• Original Assignee: Japan Display Incorporated
• Inventors: Teranishi, Yasuyuki, Noguchi, Koji, Ishizaki, Koji, Takeuchi, Takeya, Nakanishi, Takayuki
• Primary Examiner(s): Lubit, Ryan A
• Assistant Examiner(s): LANDIS, LISA S
• Application Number:
  US13/056,315
• Publication Number:
  US 20110128254A1
• Time in Patent Office: 2,862 Days
• Field of Search: 345 87-104, 345174
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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

A capacitive type touch sensor appropriately detecting an object, and a display and an electronic device including such a touch sensor are provided. The display including a drive electrode receiving a drive signal, a detection electrode located adjacent to the drive electrode, and a dielectric material located between the drive electrode and the detection electrode defining a capacitive area. The detection electrode generates an output signal driven by the drive signal, a detection circuit electrically connected to the detection electrode sensing the output signal. A switch element is electrically connected between the detection electrode and a voltage source providing a predefined voltage level and having a first state and a second state. A display control circuit controls a voltage applied between a display common voltage electrode and a pixel electrode to display an image based on an image signal, and the display common voltage electrode serves as the drive electrode.

Claims

1. A touch sensor apparatus, comprising:

a first signal source generating a first drive signal;

a first drive electrode receiving the first drive signal as a display drive signal doubling as a touch sensor drive signal from the first signal source;

a first detection electrode located adjacent to the first drive electrode;

a dielectric material located between the first drive electrode and the first detection electrode defining a first capacitive area, wherein the first detection electrode generates a first output signal driven by the first drive signal;

a detection circuit electrically connected to the first detection electrode, the detection circuit sensing the first output signal, the detection circuit including;

a detection signal line connected to the first detection electrode;

an amplification section that amplifies the first output signal;

a switch element that is arranged between the detection signal line and a ground and that is arranged between the amplification section and the ground, and the switch element having a first state and a second state; and

a control unit controls the switch element to turn on in synchronization with a timing immediately before a polarity-reversing timing of the first drive signal;

a plurality of pixel electrodes formed on a first substrate;

a second substrate opposing the first substrate; and

a liquid crystal layer arranged between the first substrate and the second substrate,

wherein the first detection electrode is formed between the second substrate and a polarizing plate,

wherein according to a timing control signal which is in synchronization with the timing immediately before the polarity-reversing timing of the first drive signal, and the timing immediately before the first drive signal is supplied to the first drive electrode or synchronized with the timing immediately before the first drive signal is stopped, indicating a timing to alternatively switch between turned on and turned off, the switch element forces the first detection electrode to a ground voltage when the switch element is turned on, the switch element allows the first detection electrode to float when the switch element is turned off, and

wherein the detection circuit determines a first detection result by comparing the first output signal to a signal threshold, the first detection result indicative of whether the first capacitive area was in a touch state.

2. The touch sensor apparatus of claim 1, further comprising:

a second signal source generating a second drive signal; and

a second drive electrode receiving the second drive signal from the second signal source;

wherein the first detection electrode is located adjacent to the second drive electrode;

wherein the dielectric material is located between the second drive electrode and the first detection electrode defining a second capacitive area;

wherein the first detection electrode generates a second output signal driven by the second drive signal;

wherein the detection circuit senses the second output signal; and

wherein the detection circuit determines a second detection result by comparing the second output signal to the signal threshold, the second detection result indicative of whether the second capacitive area was in the touch state.

3. The touch sensor apparatus of claim 2, wherein:

the first drive signal and the second drive signal are sequentially applied to the first drive electrode and the second drive electrode; and

the first output signal and the second output signal are sequentially sensed with respect to the first drive signal and the second drive signal being sequentially applied.

4. The touch sensor apparatus of claim 3, wherein:

a second detection electrode located adjacent to the first drive electrode and the second drive electrode;

the dielectric material is located between the second detection electrode and the first drive electrode defining a third capacitive area, wherein the second detection electrode generates a third output signal driven by the first drive signal;

the dielectric material is located between the second detection electrode and the second drive electrode defining a fourth capacitive area, wherein the second detection electrode generates a fourth output signal driven by the second drive signal;

the detection circuit is electrically connected to the second detection electrode, the detection circuit sensing the third output signal and the fourth output signal;

the detection circuit determines a third detection result by comparing the third output signal to the signal threshold, the third detection result indicative of whether the third capacitive area was in the touch state; and

the detection circuit determines a fourth detection result by comparing the fourth output signal to the signal threshold, the fourth detection result indicative of whether the fourth capacitive area was in the touch state.

5. The touch sensor apparatus of claim 4, wherein the first output signal, the second output signal, the third output signal, and the fourth output signal are sequentially sensed from the first detection electrode and the second detection electrode.

6. The touch sensor apparatus of claim 1, wherein the first detection electrode is part of a display.

7. The touch sensor apparatus of claim 1, wherein the first signal source is included in a display control circuit and the first drive electrode is a display common voltage electrode, such that the display control circuit controls a voltage applied between the display common voltage electrode and a pixel electrode so as to display an image based on an image signal, the display common voltage electrode receiving the first drive signal.

8. The touch sensor apparatus of claim 1, wherein the detection circuit is formed in a perimeter region on a pixel substrate and integrated with circuit elements for display control.

9. The touch sensor apparatus of claim 1, wherein the detection circuit includes at least one of the amplification section, a filter section, a rectification section, a smoothing section, an analog to digital converter section, a signal processing section, and a coordinate extraction section.

10. The touch sensor apparatus of claim 1, further comprising a precharge power source electrically connected to the switch element and providing the predefined voltage level, wherein the precharge power source sequentially provides a first predefined voltage level and a second predefined voltage level.

11. The touch sensor apparatus of claim 1, further comprising:

a second detection electrode located adjacent to the first drive electrode and displaced from the first detection electrode in a first direction;

a third detection electrode located adjacent to the first drive electrode and displaced from the first detection electrode in a second direction; and

a fourth detection electrode located adjacent to the first drive electrode and displaced from the second detection electrode in the second direction and displaced from the third electrode in the first direction;

wherein the dielectric material is located between the first drive electrode and the second detection electrode defining a second capacitive area, the dielectric material is located between the first drive electrode and the third detection electrode defining a third capacitive area, and the dielectric material is located between the first drive electrode and the fourth detection electrode defining a fourth capacitive area;

wherein the second detection electrode generates a second output signal driven by the first drive signal;

wherein the third detection electrode generates a third output signal driven by the first drive signal;

wherein the fourth detection electrode generates a fourth output signal driven by the first drive signal;

wherein the detection circuit determines a second detection result by comparing the second output signal to the signal threshold, the second detection result indicative of whether the second capacitive area was in the touch state;

wherein the detection circuit determines a third detection result by comparing the third output signal to the signal threshold, the third detection result indicative of whether the third capacitive area was in the touch state; and

wherein the detection circuit determines a fourth detection result by comparing the fourth output signal to the signal threshold, the fourth detection result indicative of whether the fourth capacitive area was in the touch state.

30. The touch sensor apparatus of claim 1, wherein the first detection electrode includes a transparent electrode of ITO.

12. A display apparatus, comprising:

a drive electrode receiving a drive signal as a display drive signal doubling as a touch sensor drive signal;

a detection electrode located adjacent to the drive electrode;

a dielectric material located between the drive electrode and the detection electrode defining a capacitive area, wherein the detection electrode generates an output signal driven by the drive signal;

a plurality of pixel electrodes formed on a first substrate;

a second substrate opposing the first substrate; and

a liquid crystal layer arranged between the first substrate and the second substrate,

wherein the detection electrode is formed between the second substrate and a polarizing plate;

a detection circuit electrically connected to the detection electrode, the detection circuit sensing the output signal; and

a display control circuit controlling a voltage applied between a display common voltage electrode and a pixel electrode so as to display an image based on an image signal, and

wherein the detection circuit includes;

a detection signal line connected to the detection electrode;

an amplification section that amplifies the first output signal; and

a switch element that is arranged between the detection signal line and a ground and that is arranged between the amplification section and the ground, and the switch element having a first state and a second state; and

a control unit controls the switch element to turn on in synchronization with a timing immediately before a polarity-reversing timing of the first drive signal,

wherein according to a timing control signal which is in synchronization with the timing immediately before the polarity-reversing timing of the drive signal, and the timing immediately before the drive signal is supplied to the drive electrode or synchronized with the timing immediately before the drive signal is stopped, indicating a timing to alternatively switch between turned on and turned off, the switch element forces the detection electrode to a ground voltage when the switch element is turned on, the switch element allows the detection electrode to float when the switch element is turned off,

wherein the display common voltage electrode serves as the drive electrode.

13. The display apparatus of claim 12, wherein a transverse electric mode liquid crystal element is modulated by the voltage applied between the display common voltage electrode and the pixel electrode.

14. The display apparatus of claim 12, wherein the pixel electrode is located between the drive electrode and the detection electrode.

15. The display apparatus of claim 12, wherein the voltage source is a precharge power source sequentially providing a first predefined voltage level and a second predefined voltage level.

16. An electronic device, comprising:

a plurality of pixel electrodes formed on a first substrate;

a second substrate opposing the first substrate;

a liquid crystal layer arranged between the first substrate and the second substrate;

a drive electrode receiving a first drive signal as a display drive signal doubling as a touch sensor drive signal;

a detection electrode formed between the second substrate and a polarizing plate;

a capacitive type touch sensor including a capacitive area producing an output signal; and

a detection circuit sensing the output signal from a detection electrode, the detection circuit including;

a detection signal line connected to the detection electrode;

an amplification section that amplifies the first output signal; and

a switch element that is arranged between the detection signal line and a ground and that is arranged between the amplification section and the ground, and the switch element having a first state and a second state; and

a control unit controls the switch element to turn on in synchronization with a timing immediately before a polarity-reversing timing of the first drive signal,

wherein the switch element receives a timing control signal which is in synchronization with the timing immediately before the polarity-reversing timing of a drive signal, and the timing immediately before the drive signal is supplied to the drive electrode or synchronized with the timing immediately before the drive signal is stopped, allowing the switch element to alternatively switch between turned on and turned off, the switch element forces the detection electrode to a ground voltage when the switch element is turned on, the switch element allows the detection electrode to float when the switch element is turned off, and

wherein the detection circuit determines a detection result by comparing the output signal to a signal threshold, the detection result indicating whether the capacitive area was in a touch state.

17. The electronic device of claim 16, wherein the capacitive type touch sensor includes:

a signal source generating the drive signal;

a drive electrode receiving the drive signal from the signal source, the detection electrode being located adjacent to the drive electrode;

a dielectric material located between the drive electrode and the detection electrode defining a capacitive area, wherein the detection electrode generates the output signal which is driven by the drive signal.

18. The electronic device of claim 17, wherein:

the signal source generating the drive signal is one of a plurality of signal sources generating a plurality of drive signals;

the drive electrode receiving the drive signal from the signal source is one of a plurality of drive electrodes receiving the plurality of drive signals from the plurality of signal sources;

the detection electrode located adjacent to the drive electrode is one of a plurality of detection electrodes located adjacent to the plurality of drive electrodes;

the dielectric material located between the drive electrode and the detection electrode defining the capacitive area is further located between the plurality of drive electrodes and the plurality of detection electrodes defining a plurality of capacitive areas; and

the output signal driven by the drive signal is one of a plurality of output signals driven by the plurality of drive signals.

19. The electronic device of claim 16, wherein the electronic device is at least one of a television, a digital camera, a notebook personal computer, a portable terminal device, a cellular telephone, and a video camera.

20. A touch sensor apparatus, comprising:

a plurality of pixel electrodes formed on a first substrate;

a second substrate opposing the first substrate;

a liquid crystal layer arranged between the first substrate and the second substrate;

a drive electrode receiving a first drive signal as a display drive signal doubling as a touch sensor drive signal;

a detection electrode formed between the second substrate and a polarizing plate;

a capacitive area producing an output signal; and

a detection circuit sensing the output signal from a detection electrode, the detection circuit including;

a detection signal line connected to the detection electrode;

an amplification section that amplifies the first output signal; and

a switch element that is arranged between the detection signal line and a ground and that is arranged between the amplification section and the ground, and the switch element having a first state and a second state; and

a control unit controls the switch element to turn on in synchronization with a timing immediately before a polarity-reversing timing of the first drive signal,

wherein according to a timing control signal which is in synchronization with the timing immediately before the polarity-reversing timing of a drive signal, and the timing immediately before the drive signal is supplied to the drive electrode or synchronized with the timing immediately before the drive signal is stopped, indicating a timing to alternatively switch between turned on and turned off, the switch element forces the detection electrode to a ground voltage when the switch element is turned on, the switch element allows the detection electrode to float when the switch element is turned off, and

wherein the detection circuit determines a detection result indicative of whether the capacitive area was in a touch state.

21. The touch sensor apparatus of claim 20, wherein the touch state is caused by an object touching the detection electrode.

22. The touch sensor apparatus of claim 20, wherein the touch state is caused by an object coming close to touching the detection electrode.

23. The touch sensor apparatus of claim 22, wherein a change in capacitance of the capacitive area causes the detection result to indicate that the capacitive area was in the touch state.

24. The touch sensor apparatus of claim 20, wherein a change in capacitance of the capacitive area causes the detection result to indicate that the capacitive area was in the touch state.

25. The touch sensor apparatus of claim 24, wherein the change in capacitance is caused by a finger touching the capacitive area by at least one of touching a detection electrode and coming close to touching the detection electrode.

26. The touch sensor apparatus of claim 20, wherein the detection result indicates that the capacitive area was in a non-touch state.

27. The touch sensor apparatus of claim 20, further comprising:

a signal source generating the drive signal; and

a drive electrode receiving the drive signal from the signal source, the detection electrode being located adjacent to the drive electrode;

wherein the polarity of the drive signal is periodically reversed at predetermined intervals.

28. The touch sensor apparatus of claim 27, wherein the detection circuit determines the detection result by comparing the output signal to a signal threshold while the switch element is turned off at a sampling timing which is set based upon a saturation time after the polarity-reversing timing.

29. A touch sensor apparatus, comprising:

a first signal source generating a first drive signal;

a first drive electrode receiving the first drive signal as a display drive signal doubling as a touch sensor drive signal from the first signal source;

a first detection electrode located adjacent to the first drive electrode;

a plurality of pixel electrodes formed on a first substrate;

a second substrate opposing the first substrate;

a liquid crystal layer arranged between the first substrate and the second substrate,

wherein the first detection electrode is formed between the second substrate and a polarizing plate,

a dielectric material located between the first drive electrode and the first detection electrode defining a first capacitive area, wherein the first detection electrode generates a first output signal driven by the first drive signal; and

a detection circuit electrically connected to the first detection electrode, the detection circuit sensing the first output signal, and the detection circuit including;

a detection signal line connected to the first detection electrode;

an amplification section that amplifies the first output signal; and

a switch element that is arranged between the detection signal line and a ground and that is arranged between the amplification section and the ground, and the switch element having a first state and a second state; and

a control unit controls the switch element to turn on in synchronization with a timing immediately before a polarity-reversing timing of the first drive signal,

wherein according to a timing control signal which is in synchronization with the timing immediately before the polarity-reversing timing of the first drive signal, and the timing immediately before the first drive signal is supplied to the first drive electrode or synchronized with the timing immediately before the first drive signal is stopped, indicating a timing to alternatively switch between turned on and turned off, the switch element forces the first detection electrode to a ground voltage when the switch element is turned on, the switch element allows the first detection electrode to float when the switch element is turned off, and

wherein the detection circuit determines a first detection result by comparing the first output signal to a signal threshold, the first detection result indicative of whether the first capacitive area was in a touch state.