Semiconductor display device and driving method the same

• US 10,013,087 B2
• Filed: 12/18/2015
• Issued: 07/03/2018
• Est. Priority Date: 04/28/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Koyama, Jun
• Primary Examiner(s): Okebato, Sahlu
• Application Number:
  US14/974,246
• Publication Number:
  US 20160117033A1
• Time in Patent Office: 928 Days
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G06F 1/3265 Power saving in display device
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/044 by capacitive means
• 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
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2310/0286 Details of a shift registers arranged for use in a driving circuit
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/14 Detecting light within display terminals, e.g. using a single or a plurality of photosensors
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3677 suitable for active matrices only
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

It is an object to provide a semiconductor display device having a touch panel, which can reduce power consumption. The semiconductor display device includes a panel which is provided with a pixel portion and a driver circuit which controls an input of the image signal to the pixel portion, and a touch panel provided in a position overlapping with the panel in the pixel portion. The pixel portion includes a display element configured to perform display in accordance with voltage of the image signal to be input, and a transistor configured to control retention of the voltage. The transistor includes an oxide semiconductor in a channel formation region. The driving frequency of the driver circuit, that is, the number of writing operations of the image signal for a certain period is changed in accordance with an operation signal from a touch panel.

Claims

1. A display device comprising:

a pixel portion comprising;

a transistor, a channel formation region of the transistor comprising an oxide semiconductor; and

a display element electrically connected to the transistor;

a driver circuit configured to drive the pixel portion; and

a touch panel overlapping with the pixel portion,

wherein a driving frequency of the driver circuit is changed in accordance with an operation signal supplied from the touch panel, and

wherein supply of a power supply potential, a clock signal, and a start signal to the driver circuit is stopped when a still image is displayed in the pixel portion.

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

a display control circuit electrically connected to the pixel portion and the driver circuit; and

a CPU electrically connected to the touch panel and the display control circuit.

3. The display device according to claim 1, wherein an off-state current density of the transistor is less than or equal to 100 zA/μ

m.

4. The display device according to claim 1, wherein a length of displaying the still image in the pixel portion is changed in accordance with the operation signal supplied from the touch panel.

5. The display device according to claim 1, wherein the driving frequency of the driver circuit when the still image is displayed in the pixel portion is lower than the driving frequency of the driver circuit when a moving image is displayed in the pixel portion.

6. The display device according to claim 1, wherein the driver circuit is configured to input an image signal to the pixel portion in a first period when the power supply potential, the clock signal, and the start signal are supplied to the driver circuit, and is configured to stop an input of the image signal to the pixel portion in a second period when supply of the power supply potential, the clock signal, and the start signal to the driver circuit is stopped.

7. The display device according to claim 1, wherein the touch panel uses any one of a resistive system, a touch panel capacitance system, an ultrasonic system, an optics system, and an electromagnetic induction system.

8. The display device according to claim 1, wherein the touch panel comprises a plurality of first electrodes and a plurality of second electrodes overlapping with the plurality of first electrodes.

9. A display device comprising:

a pixel portion comprising;

a transistor, a channel formation region of the transistor comprising an oxide semiconductor;

a display element electrically connected to the transistor; and

a photosensor; and

a driver circuit configured to drive the pixel portion,

wherein a driving frequency of the driver circuit is changed in accordance with an operation signal supplied from the photosensor, and

wherein supply of a power supply potential, a clock signal, and a start signal to the driver circuit is stopped when a still image is displayed in the pixel portion.

10. The display device according to claim 9, further comprising:

a display control circuit electrically connected to the pixel portion and the driver circuit; and

a CPU electrically connected to the display control circuit.

11. The display device according to claim 9, wherein an off-state current density of the transistor is less than or equal to 100 zA/μ

m.

12. The display device according to claim 9, wherein a length of displaying the still image in the pixel portion is changed in accordance with the operation signal supplied from the photosensor.

13. The display device according to claim 9, wherein the driving frequency of the driver circuit when the still image is displayed in the pixel portion is lower than the driving frequency of the driver circuit when a moving image is displayed in the pixel portion.

14. The display device according to claim 9, wherein the driver circuit is configured to input an image signal to the pixel portion in a first period when the power supply potential, the clock signal, and the start signal are supplied to the driver circuit, and is configured to stop an input of the image signal to the pixel portion in a second period when supply of the power supply potential, the clock signal, and the start signal to the driver circuit is stopped.

15. The display device according to claim 9, wherein the photosensor comprises a photodiode.