Semiconductor device, and display device, driving method and electronic apparatus thereof

• US 20060208977A1
• Filed: 03/09/2006
• Published: 09/21/2006
• Est. Priority Date: 03/18/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kimura, Hajime
• Granted Patent: US 8,681,077 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2300/0465 Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0833 forming a linear amplifier or follower
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/0259 with use of an analog or digital ramp generator in the column driver or in the pixel circuit
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/30 using electroluminescent panels
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/1216 the pixel elements being capacitors
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 59/35 comprising red-green-blue [RGB] subpixels
• CPC Class Codes: H10K 59/351 comprising more than three subpixels, e.g. red-green-blue-white [RGBW]
• CPC Class Codes: H10K 59/38 : comprising colour filters or colour changing media [CCM]
• CPC Class Codes: Y02B 20/30 : Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

When light emitting elements have the same luminance, luminosity obtained from one pixel can be higher as area of a light emitting region in the pixel (also called an aperture ration) is increased. The aperture ratio of a pixel is low if the number of transistors and wires constituting the pixel is large. Thus, the invention is to decrease the number of transistors and wires constituting a pixel to increase the aperture ratio. Instead of a power supply line to which a certain potential is set, a potential supply line which controls a potential by a signal is provided; supplying an applied voltage to a light emitting element can be controlled by a signal of the potential supply line without providing a switch.

Claims

1. A semiconductor device including a pixel comprising:

an electrode;

a transistor having a gate terminal, a first terminal and a second terminal;

a first wire;

a second wire;

a capacitor for holding a potential difference between the gate terminal of the transistor and the first wire; and

a switch provided between the gate terminal and the second terminal of the transistor,

wherein the first terminal of the transistor is electrically connected to the second wire and the second terminal of the transistor is electrically connected to the electrode.

2. A semiconductor device including a pixel comprising:

an electrode;

a transistor having a gate terminal, a first terminal and a second terminal;

a first wire;

a second wire;

a capacitor for holding a potential difference between the gate terminal of the transistor and the first wire; and

a switch provided between the gate terminal and the second terminal of the transistor,

wherein the first terminal of the transistor is electrically connected to the second wire and the second terminal of the transistor is electrically connected to the electrode, and

wherein the first wire is electrically connected to the electrode through the capacitor and the switch.

3. A semiconductor device including a pixel comprising:

an electrode;

a transistor having a gate terminal, a first terminal and a second terminal;

a first wire;

a second wire;

a capacitor for holding a potential difference between the gate terminal of the transistor and the first wire; and

a switch provided between the gate terminal and the second terminal of the transistor,

wherein the first terminal of the transistor is electrically connected to the second wire and the second terminal of the transistor is electrically connected to the electrode,

wherein the first wire is electrically connected to the electrode through the capacitor and the switch, and

wherein the gate terminal of the transistor is electrically connected to the first wire through the capacitor.

4. A semiconductor device including a pixel comprising:

an electrode;

a transistor having a gate terminal, a first terminal and a second terminal;

a first wire;

a second wire;

a capacitor for holding a potential difference between the gate terminal of the transistor and the first wire;

a switch provided between the gate terminal and the second terminal of the transistor; and

at least first and second potential generating circuits,

wherein the first terminal of the transistor is electrically connected to the second wire and the second terminal of the transistor is electrically connected to the electrode,

wherein the first wire is electrically connected to the electrode through the capacitor and the switch, and

wherein the gate terminal of the transistor is electrically connected to the first wire through the capacitor.

10. The semiconductor device according to claim 4, further comprising:

a signal line driver, and

a switch provided between the signal line driver and the first wire.

5. A display device including a pixel comprising:

a light emitting element;

a driving transistor having a gate terminal, a first terminal and a second terminal and for driving the light emitting element;

a first wire;

a second wire;

a capacitor for holding a potential difference between the gate terminal of the driving transistor and the first wire; and

a switch provided between the gate terminal and the second terminal of the driving transistor,

wherein the first terminal of the driving transistor is electrically connected to the second wire and the second terminal of the driving transistor is electrically connected to a pixel electrode of the light emitting element.

13. An electronic apparatus wherein the display device according to claim 5 is included in a display portion.

6. A display device including a pixel comprising:

a light emitting element;

a driving transistor having a gate terminal, a first terminal and a second terminal and for driving the light emitting element;

a first wire;

a second wire;

a capacitor for holding a potential difference between the gate terminal of the driving transistor and the first wire; and

a switch provided between the gate terminal and the second terminal of the driving transistor,

wherein the first terminal of the driving transistor is electrically connected to the second wire and the second terminal of the driving transistor is electrically connected to a pixel electrode of the light emitting element, and

wherein the first wire is electrically connected to the electrode through the capacitor and the switch.

14. An electronic apparatus wherein the display device according to claim 6 is included in a display portion.

7. A display device including a pixel comprising:

a light emitting element;

a driving transistor having a gate terminal, a first terminal and a second terminal and for driving the light emitting element;

a first wire;

a second wire;

a capacitor for holding a potential difference between the gate terminal of the driving transistor and the first wire; and

a switch provided between the gate terminal and the second terminal of the driving transistor,

wherein the first terminal of the driving transistor is electrically connected to the second wire and the second terminal of the driving transistor is electrically connected to a pixel electrode of the light emitting element,

wherein the first wire is electrically connected to the electrode through the capacitor and the switch, and

wherein the gate terminal of the driving transistor is electrically connected to the first wire through the capacitor.

15. An electronic apparatus wherein the display device according to claim 7 is included in a display portion.

8. A display device including a pixel comprising:

a light emitting element;

a driving transistor having a gate terminal, a first terminal and a second terminal and for driving the light emitting element;

a first wire;

a second wire;

a capacitor for holding a potential difference between the gate terminal of the driving transistor and the first wire;

a switch provided between the gate terminal and the second terminal of the driving transistor, and

at least first and second potential generating circuits,

wherein the first terminal of the driving transistor is electrically connected to the second wire and the second terminal of the driving transistor is electrically connected to a pixel electrode of the light emitting element,

wherein the first wire is electrically connected to the electrode through the capacitor and the switch, and

wherein the gate terminal of the transistor is electrically connected to the first wire through the capacitor.

11. The display device according to claim 8,

a signal line driver, and

a switch provided between the signal line driver and the first wire.

16. An electronic apparatus wherein the display device according to claim 8 is included in a display portion.

9. A display device comprising:

a plurality of scan lines;

a plurality of signal lines;

a plurality of pixels which are arranged in matrix corresponding to the plurality of scan lines and the plurality of signal lines and each of which is connected to one of the plurality of scan lines and one of the plurality of signal lines;

a signal writing means for supplying a video signal which is written in the pixels to the signal lines;

a pixel selecting means for supplying a signal for selecting a pixel to be written, to the plurality of scan lines; and

a potential supplying means for supplying a potential for controlling all at one light emission/non-light emission of the pixels based on a potential of the video signal which are written in the pixels, to the signal lines.

12. The display device according to claim 9, wherein the potential supplying means includes a means for supplying a different potential per some signal lines in the plurality of signal lines.

17. A driving method of a display device including a pixel comprising:

a light emitting element;

a driving transistor having a gate terminal, a first terminal and a second terminal and for driving the light emitting element;

a first wire;

a second wire;

a capacitor for holding a potential difference between the gate terminal of the driving transistor and the first wire; and

a switch for making a portion between the gate terminal and the second terminal of the driving transistor conductive/non-conductive,

wherein the first terminal of the driving transistor is electrically connected to the second wire and the second terminal of the driving transistor is electrically connected to a pixel electrode of the light emitting element, the driving method comprising;

making the portion between the gate terminal and the second terminal of the driving transistor conductive by the switch, inputting a video signal to the first wire, and inputting to the second wire a first potential of which potential difference to an opposing electrode of the light emitting element is equal to or higher than a forward threshold voltage of the light emitting element, in writing a signal to the pixel in a signal writing period to the pixel;

making the portion between the gate terminal and the second terminal of the driving transistor non-conductive by the switch, and inputting to the second wire a second potential of which potential difference to the opposing electrode of the light emitting element is lower than the forward threshold voltage of the light emitting element when the signal writing to the pixel is completed; and

inputting a potential varying in an analog manner to the first wire and inputting the first potential to the second wire in a light emitting period.