Touch sensor, display and electronic device

• US 10,082,923 B2
• Filed: 02/13/2018
• Issued: 09/25/2018
• 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): LANDIS, LISA S
• Application Number:
  US15/895,756
• Publication Number:
  US 20180239460A1
• Time in Patent Office: 224 Days
• 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 substrate;

a plurality of pixel electrodes formed on the first substrate;

a second substrate opposing the first substrate;

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

a first signal source generating a first drive signal;

a first drive electrode receiving the first drive signal, the first drive electrode being disposed on a liquid crystal layer side of the second substrate;

a first detection electrode disposed on an observer side of the second substrate, the observer side being opposite to the liquid crystal layer side of the second substrate;

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.

2. The touch sensor apparatus of claim 1, 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.

3. The touch sensor apparatus of claim 2, 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.

4. The touch sensor apparatus of claim 3, 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.

5. The touch sensor apparatus of claim 4, 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.

6. The touch sensor apparatus of claim 5, 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.

7. The touch sensor apparatus of claim 2, 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.

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 pixel electrodes 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 the first 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 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.

12. 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.

13. The touch sensor apparatus of claim 1, wherein the first detection electrode generates the first output signal driven by the first drive signal.

14. The touch sensor apparatus of claim 1, 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.