TOUCH SENSOR, DISPLAY AND ELECTRONIC DEVICE

• US 20110128254A1
• Filed: 05/26/2010
• Published: 06/02/2011
• Est. Priority Date: 05/29/2009
• Status: Active Grant

• Current Assignee: Japan Display Incorporated
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Teranishi, Yasuyuki, Takeuchi, Takeya, Nakanishi, Takayuki, Ishizaki, Koji, Noguchi, Koji
• Granted Patent: US 9,927,925 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• 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 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; and

a switch element electrically connected to the first detection electrode, the switch element having a first state and a second state;

wherein the switch element forces the first detection electrode to a predefined voltage when the switch element is in the first state, the switch element allows the first detection electrode to float when the switch element is in the second state, and the switch element receives a timing control signal causing the switch element to alternate between the first state and the second state; 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;

wherein the switch element forces the second detection electrode to a predefined voltage level when the switch element is in the first state, and the switch element allows the second detection electrode to float when the switch element is in the second state; 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 switch element is electrically connected to the second detection electrode, the switch element forces the third detection electrode and the fourth detection electrode to a predefined voltage level when the switch element is in the first state, and the switch element allows the third detection electrode and the fourth detection electrode to float when the switch element is in the second state;

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 5, wherein the switch element includes a first switch for the first detection electrode and a second switch for the second detection electrode.

7. The touch sensor apparatus of claim 5, wherein the switch element receives the timing control signal from a timing control circuit, wherein the timing control circuit further transmits timing control signals to the first signal source to control when the first drive signal is on, to the second signal source to control when the second drive signal is on, and to an analog to digital converter section in the detection circuit to control sampling timing.

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

9. 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.

10. 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.

11. The touch sensor apparatus of claim 1, wherein the detection circuit includes at least one of an 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.

12. The touch sensor apparatus of claim 1, wherein the predefined voltage level of the switch element is a ground voltage.

13. 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.

14. 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 switch element is electrically connected to the second detection electrode, the third detection electrode, and the fourth detection electrode;

wherein the switch element forces the second detection electrode, the third detection electrode, and the fourth detection electrode to a predefined voltage level when the switch element is in the first state, and the switch element allows the second detection electrode, the third detection electrode, and the fourth detection electrode to float when the switch element is in the second state;

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.

15. A display apparatus, comprising:

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

a switch element electrically connected between the detection electrode and a voltage source providing a predefined voltage level, the switch element having a first state and a second state; 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, wherein the display common voltage electrode serves as the drive electrode.

16. The display apparatus of claim 15, wherein a transverse electric mode liquid crystal element is modulated by the voltage applied between the display common voltage electrode and the pixel electrode.

17. The display apparatus of claim 15, wherein:

the switch element forces the detection electrode to a predefined voltage level when the switch element is in the first state, the switch element allows the detection electrode to float when the switch element is in the second state, and the switch element receives a timing control signal causing the switch element to alternate between the first state and the second state; and

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

18. The display apparatus of claim 15, wherein the pixel electrode is located between the drive electrode and the detection electrode.

19. The display apparatus of claim 15, wherein the voltage source provides a ground voltage.

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

21. An electronic device, comprising:

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

a detection circuit sensing the output signal from a detection electrode; and

a switch element having a first state and a second state, the switch element forcing the detection electrode to a predefined voltage level when the switch element is in the first state, the switch element allowing the detection electrode to float when the switch element is in the second state, and the switch element alternating between the first state and the second state;

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.

22. The electronic device of claim 21, wherein the capacitive type touch sensor includes:

a signal source generating a 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.

23. The electronic device of claim 22, 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;

the switch element forces the plurality of detection electrodes to a predefined voltage level when the switch element is in the first state, the switch element allows the plurality of detection electrodes to float when the switch element is in the second state; and

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

24. The electronic device of claim 21, further comprising a timing control section, wherein the switch element receives a timing control signal from the timing control section causing the switch element to alternate between the first state and the second state.

25. The electronic device of claim 21, wherein the first state of the switch element is closed and the second state of the switch element is open.

26. The electronic device of claim 21, wherein the first state of the switch element is on and the second state of the switch element is off.

27. The electronic device of claim 21, 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.

28. A touch sensor apparatus, comprising:

a capacitive area producing an output signal;

a detection circuit sensing the output signal from a detection electrode; and

a switch element having a first state and a second state, the switch element forcing the detection electrode to a predefined voltage level when the switch element is in the first state, the switch element allowing the detection electrode to float when the switch element is in the second state, and the switch element alternating between the first state and the second state;

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

29. The touch sensor apparatus of claim 28, wherein the touch state is caused by an object touching the detection electrode.

30. The touch sensor apparatus of claim 28, wherein the touch state is caused by an object coming close to touching the detection electrode.

31. The touch sensor apparatus of claim 30, wherein a change in capacitance of the capacitive area causes the detection result to indicate that the capacitive area was in the touch state.

32. The touch sensor apparatus of claim 28, wherein a change in capacitance of the capacitive area causes the detection result to indicate that the capacitive area was in the touch state.

33. The touch sensor apparatus of claim 32, 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.

34. The touch sensor apparatus of claim 28, wherein the detection result indicates that the capacitive area was in a non-touch state.

35. The touch sensor apparatus of claim 28, wherein the switch element receives a timing control signal causing the switch element to alternate between the first state and the second state and controlling the duration of switching between the first state and the second state.

36. The touch sensor apparatus of claim 35, wherein the timing control signal causes the switch element to be in the first state for a shorter period of time than the timing control signal causes the switch element to be in the second state.

37. The touch sensor apparatus of claim 36, wherein the predefined voltage level is a ground voltage.

38. The touch sensor apparatus of claim 28, further comprising:

a signal source generating a 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, and the switch element changes from the first state to the second state before a polarity-reversing timing of the drive signal in synchronization with the predetermined intervals.

39. The touch sensor apparatus of claim 38, wherein the detection circuit determines the detection result by comparing the output signal to a signal threshold during the second state at a sampling timing which is set based upon a saturation time after the polarity-reversing timing.