Display device and drive method therefor

Patent metadata

Field	Value
Publication number	US-2016155377-A1
Application number	US-201414900224-A
Country	US
Kind code	A1
Filing date	Jun 20, 2014
Priority date	Jun 27, 2013
Publication date	Jun 2, 2016
Grant date	—

Abstract

A monitor line electrically connectable with sources of drive transistors and positive electrodes of electro-optical elements is provided. A drive method includes a step of detecting the characteristics of a drive transistor, a step of detecting the characteristics of an electro-optical element, a step of storing characteristics data obtained on the basis of a result of the detection of the characteristics, as correction data for correcting a video signal, and a step of correcting the video signal on the basis of the correction data. Here, the length of a selection period is set to be equal for a monitored row and an unmonitored row. In addition, a potential given to the monitor line for the detection of the characteristics of the drive transistors and a potential given to the monitor line for the detection of the characteristics of the electro-optical elements are made different.

First claim

1 . A drive method for a display device having a pixel matrix of n rows and m columns constituted by n×m (where n and m are integers greater than or equal to 2) pixel circuits, each including an electro-optical element whose brightness is controlled with current and a drive transistor for controlling a current to be supplied to the electro-optical element, the drive method comprising:
a drive transistor characteristics detecting step of detecting characteristics of the drive transistor;
a correction data storing step of causing a correction data storage unit prepared in advance to store, as correction data for correcting a video signal, characteristics data obtained on the basis of a detection result in the drive transistor characteristics detecting step; and
a video signal correcting step of correcting the video signal on the basis of the correction data stored in the correction data storage unit, and generating a data signal to be supplied to the n×m pixel circuits,
wherein the display device has, for each column in the pixel matrix, a monitor line electrically connectable with sources of the drive transistors and positive electrodes of the electro-optical elements,
wherein processing of the drive transistor characteristics detecting step is performed for only one row in the pixel matrix per period of one frame,
wherein, when a row for which the processing of the drive transistor characteristics detecting step is performed within each frame period is defined as a monitored row and a row other than the monitored row is defined as an unmonitored row, a period of one frame for the monitored row includes a drive transistor characteristics detection period during which the processing of the drive transistor characteristics detecting step is performed, and a light emission period during which the electro-optical elements are enabled to emit light,
wherein, for the monitored row, the monitor line is electrically connected to the source of the drive transistor and the positive electrode of the electro-optical element throughout the drive transistor characteristics detection period and the light emission period, and
wherein a potential given to the monitor line during the drive transistor characteristics detection period and a potential given to the monitor line during the light emission period are made different so that a current flows through only the drive transistor out of the drive transistor and the electro-optical element during the drive transistor characteristics detection period and so that a current flows through only the electro-optical element out of the drive transistor and the electro-optical element during the light emission period.

2 . The drive method according to claim 1 , further comprising an electro-optical element characteristics detecting step of detecting characteristics of the electro-optical element,
wherein processing of the electro-optical element characteristics detecting step is performed during the light emission period, and wherein, in the correction data storing step, characteristics data obtained on the basis of a detection result in the electro-optical element characteristics detecting step is further stored in the correction data storage unit as the correction data.

3 . The drive method according to claim 2 , wherein, in the electro-optical element characteristics detecting step, a current flowing through the electro-optical element with a constant voltage being given to the electro-optical element is measured, so that the characteristics of the electro-optical element are detected.

4 . The drive method according to claim 3 , wherein, in the electro-optical element characteristics detecting step, a length of a time period during which the constant voltage is given to the electro-optical element is adjusted in accordance with target brightness.

5 . The drive method according to claim 4 , wherein, in the electro-optical element characteristics detecting step, the constant voltage, which has a plurality of levels within a range in which an integral value of light emission current for a period of one frame is equal to a value corresponding to target gradation, is given to the electro-optical element, so that a plurality of properties are detected as the characteristics of the electro-optical element.

6 . The drive method according to claim 3 , wherein the display device includes a current measurement circuit that measures a current of the monitor line,
wherein, in the drive transistor characteristics detecting step, the current measurement circuit measures a current of the monitor line, so that characteristics of the drive transistor are detected, and wherein, in the electro-optical element characteristics detecting step, the current measurement circuit measures a current of the monitor line, so that characteristics of the electro-optical element are detected.

7 . The drive method according to claim 2 , wherein, in the electro-optical element characteristics detecting step, a voltage across the positive electrode of the electro-optical element is measured with a constant current being given to the electro-optical element, so that the characteristics of the electro-optical element are detected.

8 . The drive method according to claim 7 , wherein, in the electro-optical element characteristics detecting step, a length of a time period during which the constant current is given to the electro-optical element is adjusted in accordance with target brightness.

9 . The drive method according to claim 8 , wherein, in the electro-optical element characteristics detecting step, the constant current, which has a plurality of levels within a range in which an integral value of light emission current for a period of one frame is equal to a value corresponding to target gradation, is given to the electro-optical element, so that a plurality of properties are detected as the characteristics of the electro-optical element.

10 . The drive method according to claim 7 , wherein
the display device includes
a current measurement circuit that measures a current of the monitor line, and
a voltage measurement circuit that measures a voltage across the monitor line,
wherein, in the drive transistor characteristics detecting step, the current measurement circuit measures a current of the monitor line, so that characteristics of the drive transistor are detected, and wherein, in the electro-optical element characteristics detecting step, the voltage measurement circuit measures a voltage across the monitor line, so that characteristics of the electro-optical element are detected.

11 . The drive method according to claim 2 , wherein the processing of the electro-optical element characteristics detecting step is not performed on a pixel displayed in black or substantially in black within the pixel matrix of n rows and m columns.

12 . The drive method according to claim 2 , further comprising:
a temperature detecting step of detecting a temperature; and a temperature change compensating step of subjecting the characteristics data to correction based on the temperature detected in the temperature detecting step, wherein, in the correction data storing step, data obtained in processing of the temperature change compensating step is stored in the correction data storage unit as the correction data.

13 . The drive method according to claim 1 , wherein, in the drive transistor characteristics detecting step, a current flowing between a drain and source of the drive transistor is measured with a voltage between a gate and source of the drive transistor being set to a predetermined magnitude, so that the characteristics of the drive transistor

Assignees

• Sharp Kk

Inventors

• Kishi Noritaka

Classifications

• G09G2320/043

  Preventing or counteracting the effects of ageing · CPC title

• G09G2300/0842

  forming a memory circuit, e.g. a dynamic memory with one capacitor · CPC title

• G09G2320/0295

  by monitoring each display pixel · CPC title

• G09G2310/0218

  with collection of electrodes in groups for n-dimensional addressing · CPC title

• G09G2300/043

  Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver · CPC title