Display device and electronic apparatus

• US 8,169,432 B2
• Filed: 08/06/2009
• Issued: 05/01/2012
• Est. Priority Date: 08/08/2008
• Status: Active Grant

• Current Assignee: JDI Design and Development GK
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yamamoto, Tetsuro, Yamashita, Junichi, Jinta, Seiichiro, Sugimoto, Hideki, Uchino, Katsuhide
• Primary Examiner(s): Shankar, Vijay
• Application Number:
  US12/461,278
• Publication Number:
  US 20100033476A1
• Time in Patent Office: 999 Days
• Field of Search: 345 76- 83, 345 90-100, 345204-215, 3151691-1694
• US Class Current: 345/214
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs

Abstract

A sampling transistor in embodiments of the present invention is kept at the on-state with a time width shorter than one horizontal cycle, during the period from the rising of a control pulse supplied from a scanner to the falling of the control pulse, and samples a video signal Vsig from a signal line SL to write the video signal Vsig to a hold capacitor. A sampling transistor T1 has a double gate structure in which a pair of transistor elements are connected in common. This suppresses change in the threshold voltage of the sampling transistor.

Claims

1. An electronic apparatus including

a main body part and

a display part that displays information output from the main body part, the display part comprising:

a pixel array part configured to include

scan lines disposed along rows,

signal lines disposed along columns, and

pixels that are disposed at intersections of the scan lines and the signal lines and are arranged in a matrix; and

a drive part configured to drive the pixel array part and include

a control scanner and

a signal selector,

the control scanner sequentially applying a control pulse to the scan lines with a predetermined horizontal cycle to thereby line-sequentially scan the pixels on a row-by-row basis, the signal selector supplying a video signal to the signal lines disposed along the columns in matching with the line-sequential scanning, wherein

the pixel includes

a sampling transistor having a gate connected to the scan line and a source and a drain one of which is connected to the signal line,

a drive transistor having a gate connected to the other of the source and the drain of the sampling transistor and a source and a drain one of which is connected to a power supply,

a light-emitting element connected to the other of the source and the drain of the drive transistor, and

a hold capacitor connected between the source and the gate of the drive transistor,

the sampling transistor is kept at an on-state during a period from rising of a control pulse supplied from the control scanner to falling of the control pulse with a time width shorter than one horizontal cycle, and samples a video signal from the signal line to write the video signal to the hold capacitor,

the sampling transistor has a double gate structure in which a pair of transistor elements are connected in series between the signal line and the gate of the drive transistor and gates of the pair of transistor elements are connected in common, and

the drive transistor causes a drive current dependent on a video signal written to the hold capacitor to flow to the light-emitting element for light emission.

2. A display device comprising:

pixel array means for including

scan lines disposed along rows,

signal lines disposed along columns, and

pixels that are disposed at intersections of the scan lines and the signal lines and are arranged in a matrix; and

drive means for driving the pixel array means and including

a control scanner and

a signal selector,

the control scanner sequentially applying a control pulse to the scan lines with a predetermined horizontal cycle to thereby line-sequentially scan the pixels on a row-by-row basis, the signal selector supplying a video signal to the signal lines disposed along the columns in matching with the line-sequential scanning, wherein

the pixel includes

a sampling transistor having a gate connected to the scan line and a source and a drain one of which is connected to the signal line,

a drive transistor having a gate connected to the other of the source and the drain of the sampling transistor and a source and a drain one of which is connected to a power supply,

a light-emitting element connected to the other of the source and the drain of the drive transistor, and

a hold capacitor connected between the source and the gate of the drive transistor,

the sampling transistor is kept at an on-state during a period from rising of a control pulse supplied from the control scanner to falling of the control pulse with a time width shorter than one horizontal cycle, and samples a video signal from the signal line to write the video signal to the hold capacitor,

the sampling transistor has a double gate structure in which a pair of transistor elements are connected in series between the signal line and the gate of the drive transistor and gates of the pair of transistor elements are connected in common, and

the drive transistor causes a drive current dependent on a video signal written to the hold capacitor to flow to the light-emitting element for light emission.

3. An electronic apparatus including

a main body part and

a display part that displays information output from the main body part, the display part comprising:

pixel array means for including

scan lines disposed along rows,

signal lines disposed along columns, and

pixels that are disposed at intersections of the scan lines and the signal lines and are arranged in a matrix; and

drive means for driving the pixel array means and including

a control scanner and

a signal selector,

the control scanner sequentially applying a control pulse to the scan lines with a predetermined horizontal cycle to thereby line-sequentially scan the pixels on a row-by-row basis, the signal selector supplying a video signal to the signal lines disposed along the columns in matching with the line-sequential scanning, wherein

the pixel includes

a sampling transistor having a gate connected to the scan line and a source and a drain one of which is connected to the signal line,

a drive transistor having a gate connected to the other of the source and the drain of the sampling transistor and a source and a drain one of which is connected to a power supply,

a light-emitting element connected to the other of the source and the drain of the drive transistor, and

a hold capacitor connected between the source and the gate of the drive transistor,

the sampling transistor is kept at an on-state during a period from rising of a control pulse supplied from the control scanner to falling of the control pulse with a time width shorter than one horizontal cycle, and samples a video signal from the signal line to write the video signal to the hold capacitor,

the sampling transistor has a double gate structure in which a pair of transistor elements are connected in series between the signal line and the gate of the drive transistor and gates of the pair of transistor elements are connected in common, and

the drive transistor causes a drive current dependent on a video signal written to the hold capacitor to flow to the light-emitting element for light emission.

4. A display device comprising:

a pixel array part configured to include

scan lines disposed along rows,

signal lines disposed along columns, and

pixels that are disposed at intersections of the scan lines and the signal lines and are arranged in a matrix; and

a drive part configured to drive the pixel array part and include

a control scanner and

a signal selector,

the control scanner sequentially applying a control pulse to the scan lines with a predetermined horizontal cycle to thereby line-sequentially scan the pixels on a row-by-row basis, the signal selector supplying a video signal to the signal lines disposed along the columns in matching with the line-sequential scanning, wherein

the pixel includes

a sampling transistor having a gate connected to the scan line and a source and a drain one of which is connected to the signal line,

a drive transistor having a gate connected to the other of the source and the drain of the sampling transistor and a source and a drain one of which is connected to a power supply,

a light-emitting element connected to the other of the source and the drain of the drive transistor, and

a hold capacitor connected between the source and the gate of the drive transistor,

the sampling transistor is kept at an on-state during a period from rising of a control pulse supplied from the control scanner to falling of the control pulse with a time width shorter than one horizontal cycle, and samples a video signal from the signal line to write the video signal to the hold capacitor,

the sampling transistor has a double gate structure in which a pair of transistor elements are connected in series between the signal line and the gate of the drive transistor and gates of the pair of transistor elements are connected in common, and

the drive transistor causes a drive current dependent on a video signal written to the hold capacitor to flow to the light-emitting element for light emission.

5. The display device according to claim 4, wherein

in the sampling transistor, a capacitor is formed between the gate of the sampling transistor and an intermediate node that interconnects the pair of transistor elements.

6. The display device according to claim 5, wherein

film thickness of an insulating film that forms the capacitor is larger than film thickness of an insulating film between the gates of the pair of transistor elements and channels of the pair of transistor elements.

7. The display device according to claim 4, wherein

channel regions of the pair of transistor elements are covered by a metal that is formed on an opposite side to the gates of the pair of transistor elements with intermediary of channels of the pair of transistor elements and is at the same potential as potential of the gates of the pair of transistor elements.

8. The display device according to claim 4, wherein

the pair of transistor elements are different from each other in channel length.

9. The display device according to claim 4, wherein

of the pair of transistor elements, the transistor element closer to the signal line has channel length larger than channel length of the transistor element closer to the gate of the drive transistor.

10. The display device according to claim 9, wherein

the pair of transistor elements have the same channel width.

11. The display device according to claim 4, wherein

in the period during which the sampling transistor is kept at the on-state to sample a video signal from the signal line and write the video signal to the hold capacitor, negative feedback of a drive current flowing through the drive transistor to the hold capacitor is carried out to thereby give correction for mobility of the drive transistor to the video signal written to the hold capacitor.