Display device and electronic device

• US 8,599,124 B2
• Filed: 11/24/2009
• Issued: 12/03/2013
• Est. Priority Date: 05/20/2005
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Koyama, Jun, Tanada, Yoshifumi, Osame, Mitsuaki, Kimura, Hajime, Fukumoto, Ryota, Yanai, Hiromi
• Primary Examiner(s): SPAR, ILANA L
• Application Number:
  US12/624,638
• Publication Number:
  US 20100066653A1
• Time in Patent Office: 1,470 Days
• Field of Search: 345/204, 345/207, 345/76, 345/77, 345/82, 345/87, 315/169.3
• US Class Current: 345/100
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• 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 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• 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 2310/0283 Arrangement of drivers for different directions of scanning
• CPC Class Codes: G09G 2310/0289 Details of voltage level shifters arranged for use in a driving circuit
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/001 using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across 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 59/1216 the pixel elements being capacitors
• CPC Class Codes: H10K 59/13 comprising photosensors that control luminance

Abstract

It is an object of the present invention to provide a display device in which images can be seen under a dark place to intense external light. In the display device, display is performed by changing the gray scale number depending on external light intensity, and display modes can be switched depending on contents displayed on the screen. An analog mode and a digital mode are switched depending on external light intensity. In an analog digital switching circuit, when a video signal is an analog value, a signal is outputted to a pixel array without any change and, when the video signal is a digital value, the signal is outputted to a circuit that performs a digital operation such as a latch circuit. Consequently, display gray scales of a pixel are changed appropriately. Accordingly, a clear image can be displayed. For example, it is possible to ensure visibility in a wide range of a dark place or under indoor florescent light to outdoor sun light.

Claims

1. A light-emitting device comprising:

a light-emitting element including an EL layer between an electrode and an opposite electrode;

a selecting transistor including a gate, a source and a drain, wherein one of the source and the drain is electrically connected to a source signal line;

a driving transistor including a gate, a source and a drain, wherein one of the source and the drain of the driving transistor is electrically connected to the electrode of the light-emitting element, the other of the source and the drain of the driving transistor is electrically connected to a power supply line, and the gate of the driving transistor is electrically connected to the other of the source and the drain of the selecting transistor;

a photo-sensor configured to detect an external light, wherein the photo-sensor includes a photoelectric conversion element and a current-voltage conversion circuit;

a source driver including a shift register, an analog digital switching circuit, and a digital data processing circuit, wherein the analog digital switching circuit is provided between the shift register and the digital data processing circuit; and

a display mode switching control circuit electrically connected to the photo-sensor, wherein the display mode switching control circuit outputs a display mode control signal to the analog digital switching circuit.

2. A light-emitting device according to claim 1, wherein the photoelectric conversion element includes a first electrode, a p-type layer over the first electrode, an i-type layer over the p-type layer, an n-type layer over the i-type layer, and a second electrode over the n-type layer.

3. A light-emitting device according to claim 1, wherein the photoelectric conversion element is formed so as not to overlap the light-emitting element via an insulating film.

4. A light-emitting device according to claim 1, wherein the display mode switching control circuit is configured to switch between an analog gray scale method and a digital gray scale method.

5. A light-emitting device according to claim 1, wherein the light-emitting device is incorporated in one selected from the group consisting of a camera, a computer, a goggle-type display, an image reproducing device, and a phone.

6. A light-emitting device comprising:

a light-emitting element including an EL layer between an electrode and an opposite electrode;

a selecting transistor including a gate, a source and a drain, wherein one of the source and the drain is electrically connected to a source signal line;

a driving transistor including a gate, a source and a drain, wherein one of the source and the drain of the driving transistor is electrically connected to the electrode of the light-emitting element, the other of the source and the drain of the driving transistor is electrically connected to a power supply line, and the gate of the driving transistor is electrically connected to the other of the source and the drain of the selecting transistor;

a photo-sensor configured to detect an external light, wherein the photo-sensor includes a photoelectric conversion element and a current-voltage conversion circuit;

an amplifier whose input is connected to an output of the current-voltage conversion circuit;

a source driver including a shift register, an analog digital switching circuit, and a digital data processing circuit, wherein the analog digital switching circuit is provided between the shift register and the digital data processing circuit; and

a display mode switching control circuit electrically connected to the amplifier, wherein the display mode switching control circuit outputs a display mode control signal to the analog digital switching circuit.

7. A light-emitting device according to claim 6, wherein the photoelectric conversion element includes a first electrode, a p-type layer over the first electrode, an i-type layer over the p-type layer, an n-type layer over the i-type layer, and a second electrode over the n-type layer.

8. A light-emitting device according to claim 6, wherein the photoelectric conversion element is formed so as not to overlap the light-emitting element via an insulating film.

9. A light-emitting device according to claim 6, wherein the display mode switching control circuit is configured to switch between an analog gray scale method and a digital gray scale method.

10. A light-emitting device according to claim 6, wherein the light-emitting device is incorporated in one selected from the group consisting of a camera, a computer, a goggle-type display, an image reproducing device, and a phone.

11. A light-emitting device comprising:

a light-emitting element including an EL layer between an electrode and an opposite electrode;

a selecting transistor including a gate, a source and a drain, wherein one of the source and the drain is electrically connected to a source signal line;

a driving transistor including a gate, a source and a drain, wherein one of the source and the drain of the driving transistor is electrically connected to the electrode of the light-emitting element, the other of the source and the drain of the driving transistor is electrically connected to a power supply line, and the gate of the driving transistor is electrically connected to the other of the source and the drain of the selecting transistor;

a photo-sensor configured to detect an external light, wherein the photo-sensor includes a current mirror circuit, a photoelectric conversion element and a current-voltage conversion circuit;

a source driver including a shift register, an analog digital switching circuit, and a digital data processing circuit, wherein the analog digital switching circuit is provided between the shift register and the digital data processing circuit; and

a display mode switching control circuit electrically connected to the photo-sensor, wherein the display mode switching control circuit outputs a display mode control signal to the analog digital switching circuit.

12. A light-emitting device according to claim 11, wherein the photoelectric conversion element includes a first electrode, a p-type layer over the first electrode, an i-type layer over the p-type layer, an n-type layer over the i-type layer, and a second electrode over the n-type layer.

13. A light-emitting device according to claim 11, wherein the photoelectric conversion element is formed so as not to overlap the light-emitting element via an insulating film.

14. A light-emitting device according to claim 11, wherein the display mode switching control circuit is configured to switch between an analog gray scale method and a digital gray scale method.

15. A light-emitting device according to claim 11, wherein the light-emitting device is incorporated in one selected from the group consisting of a camera, a computer, a goggle-type display, an image reproducing device, and a phone.

16. A light-emitting device comprising:

a light-emitting element including an EL layer between an electrode and an opposite electrode;

a selecting transistor including a gate, a source and a drain, wherein one of the source and the drain is electrically connected to a source signal line;

a driving transistor including a gate, a source and a drain, wherein one of the source and the drain of the driving transistor is electrically connected to the electrode of the light-emitting element, the other of the source and the drain of the driving transistor is electrically connected to a power supply line, and the gate of the driving transistor is electrically connected to the other of the source and the drain of the selecting transistor;

a photo-sensor configured to detect an external light, wherein the photo-sensor includes a current mirror circuit, a photoelectric conversion element and a current-voltage conversion circuit;

an amplifier whose input is connected to an output of the current-voltage conversion circuit;

a source driver including a shift register, an analog digital switching circuit, and a digital data processing circuit, wherein the analog digital switching circuit is provided between the shift register and the digital data processing circuit; and

a display mode switching control circuit electrically connected to the amplifier, wherein the display mode switching control circuit outputs a display mode control signal to the analog digital switching circuit.

17. A light-emitting device according to claim 16, wherein the photoelectric conversion element includes a first electrode, a p-type layer over the first electrode, an i-type layer over the p-type layer, an n-type layer over the i-type layer, and a second electrode over the n-type layer.

18. A light-emitting device according to claim 16, wherein the photoelectric conversion element is formed so as not to overlap the light-emitting element via an insulating film.

19. A light-emitting device according to claim 16, wherein the display mode switching control circuit is configured to switch between an analog gray scale method and a digital gray scale method.

20. A light-emitting device according to claim 16, wherein the light-emitting device is incorporated in one selected from the group consisting of a camera, a computer, a goggle-type display, an image reproducing device, and a phone.