Light-emitting device capable of correcting variation in luminance among pixels

Patent metadata

Field	Value
Publication number	US-9659526-B2
Application number	US-201414479630-A
Country	US
Kind code	B2
Filing date	Sep 8, 2014
Priority date	Sep 13, 2013
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

A light-emitting device is provided, which is capable of correcting variation in luminance among pixels due to variation in electrical characteristics, such as threshold voltage or mobility, among driving transistors in a period where image display is performed. The light-emitting device includes a pixel; a first circuit configured to generate a signal including information about a value of current extracted from the pixel; and a second circuit configured to correct an image signal in accordance with the signal. The pixel includes a light-emitting element; a transistor whose drain current has a value determined in accordance with the image signal; a first switch configured to control supply of the drain current to the light-emitting element; and a second switch configured to control extraction of the drain current from the pixel and control the supply of the drain current to the light-emitting element.

First claim

What is claimed is:

1. A light-emitting device comprising:
a pixel comprising:
a transistor, a value of current flowing through the transistor determined in accordance with an image signal;
a light-emitting element directly connected to a first terminal of the transistor;
a first switch, a terminal of the first switch electrically connected to a second terminal of the transistor;
a second switch, a first terminal of the second switch electrically connected to the second terminal of the transistor; and
a first capacitor, a first terminal of the first capacitor electrically connected to a gate of the transistor and a second terminal of the first capacitor directly connected to the first terminal of the transistor;

a first circuit electrically connected to a second terminal of the second switch, the first circuit configured to generate a signal including information about the value of the current; and
a second circuit electrically connected to the first circuit, the second circuit configured to correct the image signal in accordance with the signal.

2. The light-emitting device according to claim 1 , wherein the transistor is an n-channel transistor.

3. The light-emitting device according to claim 1 , wherein the transistor comprises a channel formation region in an oxide semiconductor film.

4. The light-emitting device according to claim 1 , wherein each of the first switch and the second switch comprises a transistor comprising a channel formation region in an oxide semiconductor film.

5. The light-emitting device according to claim 1 , wherein the first circuit comprises an operational amplifier, a second capacitor, and a third switch,
wherein a first terminal of the second capacitor and a first terminal of the third switch are electrically connected to an input terminal of the operational amplifier, and
wherein a second terminal of the second capacitor and a second terminal of the third switch are electrically connected to an output terminal of the operational amplifier.

6. The light-emitting device according to claim 1 , further comprising a selection circuit electrically connected between the pixel and the first circuit.

7. A light-emitting device comprising:
a pixel comprising:
a transistor, a value of current flowing through the transistor determined in accordance with an image signal;
a light-emitting element directly connected to a first terminal of the transistor;
a first switch, a terminal of the first switch electrically connected to a second terminal of the transistor;
a second switch, a first terminal of the second switch electrically connected to the second terminal of the transistor;
a third switch, a terminal of the third switch electrically connected to the first terminal of the transistor and the light-emitting element; and
a first capacitor, a first terminal of the first capacitor electrically connected to a gate of the transistor and a second terminal of the first capacitor directly connected to the first terminal of the transistor;

a first circuit electrically connected to a second terminal of the second switch, the first circuit configured to generate a signal including information about the value of the current; and
a second circuit electrically connected to the first circuit, the second circuit configured to correct the image signal in accordance with the signal.

8. The light-emitting device according to claim 7 , wherein the transistor is an n-channel transistor.

9. The light-emitting device according to claim 7 , wherein the transistor comprises a channel formation region in an oxide semiconductor film.

10. The light-emitting device according to claim 7 , wherein each of the first switch, the second switch, and the third switch comprises a transistor comprising a channel formation region in an oxide semiconductor film.

11. The light-emitting device according to claim 7 , wherein the first circuit comprises an operational amplifier, a capacitor, and a fourth switch,
wherein a first terminal of the capacitor and a first terminal of the fourth switch are electrically connected to an input terminal of the operational amplifier, and
wherein a second terminal of the capacitor and a second terminal of the fourth switch are electrically connected to an output terminal of the operational amplifier.

12. The light-emitting device according to claim 7 , further comprising a selection circuit electrically connected between the pixel and the first circuit.

13. A light-emitting device comprising:
a pixel comprising:
a first transistor, a gate of the first transistor electrically connected to a first wiring and a first terminal of the first transistor supplied with an image signal;
a second transistor, a gate of the second transistor electrically connected to a second terminal of the first transistor;
a light-emitting element directly connected to a first terminal of the second transistor;
a third transistor, a first terminal of the third transistor electrically connected to a second terminal of the second transistor;
a fourth transistor, a first terminal the fourth transistor electrically connected to the second terminal of the second transistor; and
a first capacitor, a first terminal of the first capacitor electrically connected to the gate of the second transistor and a second terminal of the first capacitor directly connected to the first terminal of the second transistor;

a first circuit electrically connected to a second terminal of the fourth transistor, the first circuit configured to generate a signal including information about a value of current flowing through the second transistor; and
a second circuit electrically connected to the first circuit, the second circuit configured to correct the image signal in accordance with the signal,
wherein a gate of the third transistor is electrically connected to a second wiring and a gate of the fourth transistor is electrically connected to a third wiring.

14. The light-emitting device according to claim 13 , wherein each of the first transistor and the second transistor is an n-channel transistor.

15. The light-emitting device according to claim 13 , wherein each of the first transistor and the second transistor comprises a channel formation region in an oxide semiconductor film.

16. The light-emitting device according to claim 13 , wherein each of the third transistor and the fourth transistor comprises a channel formation region in an oxide semiconductor film.

17. The light-emitting device according to claim 13 , wherein the first circuit comprises an operational amplifier, a capacitor, and a switch,
wherein a first terminal of the capacitor and a first terminal of the switch are electrically connected to an input terminal of the operational amplifier, and
wherein a second terminal of the capacitor and a second terminal of the switch are electrically connected to an output terminal of the operational amplifier.

18. The light-emitting device according to claim 13 , further comprising a selection circuit electrically connected between the pixel and the first circuit.

Assignees

• Semiconductor Energy Lab

Inventors

• Miyake Hiroyuki

Classifications

• G09G2320/0295

  by monitoring each display pixel · CPC title

• G09G3/3233 Primary

  with pixel circuitry controlling the current through the light-emitting element · CPC title

• G09G2310/0291

  Details of output amplifiers or buffers arranged for use in a driving circuit · CPC title

• G09G2300/0417

  Special arrangements specific to the use of low carrier mobility technology · CPC title

• G09G2300/0861

  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 title