DISPLAY DEVICE AND ELECTRONIC APPARATUS

• US 20090115737A1
• Filed: 06/10/2008
• Published: 05/07/2009
• Est. Priority Date: 11/05/2007
• Status: Active Grant

• Current Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Original Assignee: Epson Imaging Devices Corporation (Seiko Group)
• Inventors: TOYOSHIMA, Yosuke
• Granted Patent: US 8,350,816 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

A display device of the invention includes a display panel 10 and a touch panel 22. A detector circuit 50 has switches 411 and 412. Switches 411 and 412 are alternately turned on and off repeatedly in the setting period. Touch detection is performed during a counting period that follows the setting period on the basis of required time until a voltage at the node reaches a reference voltage while the switch 411 is turned off and switch 412 is turned on. Common voltage changes in the setting period while switch 411 is turned off and switch 412 is turned on.

Claims

1. A display device comprising:

a display panel including a plurality of pixels each having a gray scale according to the difference voltage between a voltage applied to an associated pixel electrode and a voltage applied to a common electrode, the common electrode facing the pixel electrodes;

a driver circuit that supplies data signals to the pixel electrodes and supplies a common signal alternately switched between a first voltage and a second voltage higher than the first voltage to the common electrode;

a touch panel substrate that is laminated on the display panel and includes a detection electrode; and

a detector circuit that performs touch detection on the detection electrode, wherein

the detector circuit includes

a constant current source that maintains current flowing between a power supply line and a predetermined node constant,

a first switch that is disposed between the detection electrode and the node and is turned on or off,

a second switch that is disposed between the detection electrode and a grounding line and is turned on or off, and

a capacitor interposed between the node and the grounding line,

the detector circuit has a settling period in which alternately turning on and off the first and second switches is repeated and a counting period, which follows the setting period and in which touch detection on the detection electrode is performed on the basis of time required until a voltage at the node reaches a preset reference voltage while the first switch is turned off and the second switch is turned on, and

the driver circuit switches the common signal between the voltages while the second switch is turned on in the settling period.

2. The device according to claim 1, further comprising:

an oscillator that outputs a clock signal, wherein

the driver circuit switches the common signal between the voltages in response to the clock signal, and

the driver circuit turns the first and second switches on and off in response to a signal, obtained by dividing the frequency of the clock signal, in the settling period.

3. The device according to claim 1, wherein

the detector circuit includes an oscillator that outputs a clock signal,

the detector circuit turns the first and second switches on and off in response to the clock signal in the settling period, and

the driver circuit switches the common signal between the voltages in response to a signal obtained by dividing the frequency of the clock signal.

4. The device according to claim 1, wherein

the driver circuit includes an oscillator that outputs a clock signal,

the driver circuit switches the common signal between the voltages in response to the clock signal, and

the detector circuit turns the first and second switches on and off in response to the clock signal in the settling period.

5. An electronic apparatus comprising the display device according to claim 1.