Display device

• US 9,223,434 B2
• Filed: 10/29/2014
• Issued: 12/29/2015
• Est. Priority Date: 04/19/2012
• Status: Active Grant

• Current Assignee: Japan Display Incorporated
• Original Assignee: Japan Display Incorporated
• Inventors: Nagata, Koji, Doi, Koji
• Primary Examiner(s): OSORIO, RICARDO
• Application Number:
  US14/526,945
• Publication Number:
  US 20150116246A1
• Time in Patent Office: 426 Days
• Field of Search: 345/174, 345/104
• US Class Current: 1/1
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G06F 2203/04102 Flexible digitiser, i.e. constructional details for allowing the whole digitising part of a device to be flexed or rolled like a sheet of paper
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• 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 3/0445 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 display device includes a display panel, a touch panel control unit, a plurality of scanning electrodes formed on the display panel, a plurality of detection electrodes formed on the display panel so as to intersect with the plurality of scanning electrodes, a drive signal supply unit for inputting a drive signal to each of the scanning electrodes, and a detection unit for detecting a detection signal from each of the detection electrodes. The touch panel control unit supplies the driving signal to each of the scanning electrodes from the drive signal supply unit to enable detection of a touch position of a detection object based on the detection signal detected, and supplies the driving signal to all of the scanning electrodes collectively from the drive signal supply unit to enable detection of approach of the detection object to the touch panel based on the detection signal detected.

Claims

1. A display device comprising:

a display panel;

a touch panel control unit;

a plurality of scanning electrodes formed on the display panel;

a plurality of detection electrodes formed on the display panel so as to intersect with the plurality of scanning electrodes;

a drive signal supply unit for inputting a drive signal to each of the scanning electrodes; and

a detection unit for detecting a detection signal from each of the detection electrodes;

wherein the touch panel control unit supplies the driving signal to each of the scanning electrodes from the drive signal supply unit so as to enable detection of a touch position of a detection object based on the detection signal detected; and

supplies the driving signal to all of the scanning electrodes collectively from the drive signal supply unit so as to enable detection of approach of the detection object to the touch panel based on the detection signal detected.

2. The display device according to claim 1,

wherein the drive signal supply unit has

a first switching element that supplies a first drive voltage to each of the plurality of scanning electrodes, and

a second switching element that supplies a second drive voltage to each of the plurality of scanning electrodes,

wherein the detection unit has

an integration circuit in which a reference voltage is input to one terminal,

a third switching element that is connected between each of the detection electrodes and the other terminal of the integration circuit, and

a fourth switching element that is connected between each of the detection electrodes and the one terminal of the integration circuit,

the first switching element and the second switching element are provided for each of the scanning electrodes, and

the integration circuit, the third switching element and the fourth switching element are provided for each of the detection electrodes.

3. The display device according to claim 2,

wherein a touch position detection period of the detection object has a reset period and a detection period for each of the scanning electrodes;

wherein in the reset period in a scanning electrode of a scanning target to which the drive signal is input, the first switching element of the scanning electrode of the scanning target is turned off, the second switching element of the scanning electrode of the scanning target is turned on, the first switching element and the second switching element of the scanning electrode other than the scanning target are turned off, the third switching elements of all the detection electrodes are turned off, and the fourth switching elements of all the detection electrodes are turned on, capacity between the scanning electrode of the scanning target and all the detection electrodes is charged with the reference voltage;

wherein in the detection period, the first switching element of the scanning electrode of the scanning target is turned on, the second switching element of the scanning electrode of the scanning target is turned off, the first switching element and the second switching element of the scanning electrode other than the scanning target are turned off, all the third switching elements are turned on, all the fourth switching elements are turned off, and the electric current flowing in a capacity between the scanning electrode of the scanning target and all the detection electrodes is integrated by the integration circuit provided for each of the detection electrodes, and

wherein the detection unit detects the touch position of the detection object, based on the output voltage of the integration circuit provided for each of the detection electrodes.

4. The display device according to claim 2,

wherein an approach detection period of the detection object to the detected has a reset period, a charge period, and a detection period,

wherein in the reset period, the first switching elements of all the scanning electrodes are turned off, the second switching elements of all the scanning electrode are turned on, the third switching elements of all the detection electrodes are turned off, and the fourth switching elements of all the detection electrodes are turned on, and a capacity between all the scanning electrodes and all the detection electrodes is charged with the reference voltage,

wherein in the charge period, the first switching elements of all the scanning electrodes are turned on, the second switching elements of all the scanning electrodes are turned off, the third switching elements of all the detection electrodes are turned off, and the fourth switching elements of all the detection electrodes are turned off, and a capacity between all the scanning electrodes and each of the detection electrodes is charged with a sum of the reference voltage and the first driving voltage,

wherein in the detection period, the first switching elements of all the scanning electrodes are turned on, the second switching elements of all the scanning electrodes are turned off, the third switching elements of all the detection electrodes are turned on, and the fourth switching elements of all the detection electrodes are turned off, and a capacity between all the scanning electrodes and each of the detection electrodes is integrated by the integration circuit provided for each of the detection electrodes, and

wherein the detection unit detects that the detection object approaches, based on the output voltage of the integration circuit provided for each of the detection electrodes.

5. The display device according to claim 2,

wherein the first drive voltage is a higher voltage than a voltage of the second drive voltage.

6. The display device according to claim 1,

wherein the plurality of scanning electrodes and the plurality of detection electrodes are formed on different surfaces.

7. The display device according to claim 1,

wherein one electrode of the plurality of scanning electrodes and the plurality of detection electrodes is formed on a surface of an observer side of the display panel, and

the other electrode of the plurality of scanning electrodes and the plurality of detection electrodes is formed on the inside of the display panel.

8. The display device according to claim 1,

wherein the display panel is a liquid crystal display panel that has a first substrate, a second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate,

the second substrate is placed on an observer side,

one electrode of the plurality of scanning electrodes and the plurality of detection electrodes is formed on a surface of an opposite side to the liquid crystal layer of the second substrate, and

the other electrode of the plurality of scanning electrodes and the plurality of detection electrodes is formed on a surface of the liquid crystal layer side of the first substrate.

9. The display device according to claim 1,

wherein the plurality of scanning electrodes and the plurality of detection electrodes are stripe-shaped electrodes.