Liquid crystal display device and electronic apparatus having the same

• US 10,310,348 B2
• Filed: 08/23/2018
• Issued: 06/04/2019
• Est. Priority Date: 10/16/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Koyama, Jun, Miyake, Hiroyuki, Tsubuku, Masashi, Noda, Kosei
• Primary Examiner(s): Boyd, Jonathan A
• Application Number:
  US16/109,886
• Publication Number:
  US 20180364510A1
• Time in Patent Office: 285 Days
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G09G 2310/0286 Details of a shift registers arranged for use in a driving circuit
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: G09G 2330/027 Arrangements or methods related to powering off a display
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3674 Details of drivers for scan electrodes
• CPC Class Codes: G09G 3/3677 suitable for active matrices only
• CPC Class Codes: G09G 5/18 Timing circuits for raster scan displays specially adapted for television H04N ; synchronisation between the display unit and other display units, videodisc player G09G5/12
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

A liquid crystal display device includes: a driver circuit portion; a pixel portion; a signal generation circuit for generating a control signal for driving the driver circuit portion and an image signal which is supplied to the pixel portion; a memory circuit; a comparison circuit for detecting a difference of image signals for a series of frame periods among image signals stored for respective frame periods in the memory circuit; a selection circuit which selects and outputs the image signals for the series of frame periods when the difference is detected in the comparison circuit; and a display control circuit which supplies the control signal and the image signals output from the selection circuit, to the driver circuit portion when the difference is detected in the comparison circuit, and stops supplying the control signal to the driver circuit portion when the difference is not detected in the comparison circuit.

Claims

1. A liquid crystal display device comprising:

a pixel portion comprising a transistor and a liquid crystal element; and

a driver circuit portion electrically connected to the pixel portion,

wherein a channel formation region of the transistor comprises an oxide semiconductor layer,

wherein an off-state current per micrometer of a channel width of the transistor is 1×

10<sup>−

16</sup> A/μ

m or lower at a drain voltage of 6V and a gate voltage of −

5V or −

10V, and

wherein supply of a control signal to the driver circuit portion is stopped when a still image is displayed on the pixel portion.

2. The liquid crystal display device according to claim 1, wherein the oxide semiconductor layer comprises indium, gallium, and zinc.

3. The liquid crystal display device according to claim 1, wherein the oxide semiconductor layer comprises a crystal.

4. The liquid crystal display device according to claim 1, wherein the oxide semiconductor layer has a hydrogen concentration of 1×

10¹⁶/cm³ or less which is detected by secondary ion mass spectrometry.

5. The liquid crystal display device according to claim 1, wherein the oxide semiconductor layer has a carrier density which is less than 1×

10¹⁴/cm³.

6. The liquid crystal display device according to claim 1, wherein an off-state resistivity of the transistor is 1×

10⁹ Ω

m or more.

7. The liquid crystal display device according to claim 1, wherein the control signal is a high power supply potential, a low power supply potential, a clock signal, a start pulse signal, or a reset signal.

8. An electronic apparatus comprising the liquid crystal display device according to claim 1.