Pixel circuit and organic light emitting display device including the same

Patent metadata

Field	Value
Publication number	US-2017193896-A1
Application number	US-201615394306-A
Country	US
Kind code	A1
Filing date	Dec 29, 2016
Priority date	Dec 30, 2015
Publication date	Jul 6, 2017
Grant date	—

Abstract

A pixel circuit includes an OLED, an OLED driving block, a first switch, and a second switch. The OLED has an anode and a cathode connected to ELVSS. The OLED driving block connected between the anode and ELVDD controls a driving current flowing through the OLED, a first switch is turned on or off responding to a first control-signal and transfers a sensing-bias-voltage to the anode when turned on. The second switch is turned on or off responding to a second control-signal and transfers a deterioration-sensing-voltage to the anode when turned on. In a display mode, the first and second switches are turned off. In a deterioration sensing mode, the first switch is turned on and the second switch is turned off during a first time, and the first switch is turned off and the second switch is turned on during a second time.

First claim

What is claimed is:

1 . A pixel circuit comprising:
an organic light emitting diode having an anode and a cathode, the cathode being connected to a low power voltage; an organic light emitting diode driving block connected between the anode of the organic light emitting diode and a high power voltage and configured to control a driving current flowing through the organic light emitting diode based on a data signal applied via a data-line; a first switch configured to be turned on or off in response to a first control signal and to transfer a sensing bias voltage to the anode of the organic light emitting diode when being turned on; and a second switch configured to be turned on or off in response to a second control signal and to transfer a deterioration sensing voltage to the anode of the organic light emitting diode when being turned on, wherein, in a display mode, the first and second switches are turned off, and wherein, in a deterioration sensing mode, the first switch is turned on and the second switch is turned off during a first time, and the first switch is turned off and the second switch is turned on during a second time following the first time.

2 . The pixel circuit of claim 1 , wherein the second switch is connected between the data-line and the anode of the organic light emitting diode, and
wherein the deterioration sensing voltage is applied via the data-line during the second time of the deterioration sensing mode.

3 . The pixel circuit of claim 2 , wherein the first and second switches are implemented by p-channel metal oxide semiconductor (PMOS) transistors,
wherein the first switch is turned on when the first control signal has a low voltage level, and the second switch is turned on when the second control signal has the low voltage level, and wherein the first switch is turned off when the first control signal has a high voltage level, and the second switch is turned off when the second control signal has the high voltage level.

4 . The pixel circuit of claim 2 , wherein the first and second switches are implemented by n-channel metal oxide semiconductor (NMOS) transistors,
wherein the first switch is turned on when the first control signal has a high voltage level, and the second switch is turned on when the second control signal has the high voltage level, and wherein the first switch is turned off when the first control signal has a low voltage level, and the second switch is turned off when the second control signal has the low voltage level.

5 . The pixel circuit of claim 1 , wherein a sensing bias current that is generated based on the sensing bias voltage applied to the anode of the organic light emitting diode and the low power voltage applied to the cathode of the organic light emitting diode flows through the organic light emitting diode during the first time of the deterioration sensing mode.

6 . The pixel circuit of claim 5 , wherein the first time of the deterioration sensing mode is set to be longer than or equal to a time during which a temperature of the organic light emitting diode reaches a predetermined sensing reference temperature as the sensing bias current flows through the organic light emitting diode.

7 . The pixel circuit of claim 1 , wherein a deterioration sensing current that is generated based on the deterioration sensing voltage applied to the anode of the organic light emitting diode and the low power voltage applied to the cathode of the organic light emitting diode flows through the organic light emitting diode during the second time of the deterioration sensing mode.

8 . The pixel circuit of claim 7 , wherein the second time of the deterioration sensing mode is a time generated by subtracting the first time of the deterioration sensing mode from a predetermined sensing allowable time for sensing deterioration of the organic light emitting diode.

9 . An organic light emitting display device comprising:
a display panel including a plurality of pixel circuits each including an organic light emitting diode; a scan driving part configured to provide a scan signal to the display panel; a data driving part configured to provide a data signal to the display panel; a deterioration compensating part configured to control a sensing bias current to flow through the organic light emitting diode during a first time, to control a deterioration sensing current to flow through the organic light emitting diode during a second time following the first time, to determine deterioration of the organic light emitting diode by comparing the deterioration sensing current with a predetermined sensing reference current, and to generate deterioration compensation information for compensating for the deterioration of the organic light emitting diode in a deterioration sensing mode; and a timing control part configured to control the scan driving part, the data driving part, and the deterioration compensating part and to compensate image data corresponding to the data signal based on the deterioration compensation information.

10 . The display device of claim 9 , wherein the deterioration compensating part is implemented inside the timing control part or the data driving part.

11 . The display device of claim 9 , wherein the deterioration sensing mode is executed at a time point when the display panel is powered on or off.

12 . The display device of claim 9 , wherein, in the deterioration sensing mode, the deterioration compensating part generates the deterioration compensation information for all of the plurality of pixel circuits or generates the deterioration compensation information for some of the pixel circuits.

13 . The display device of claim 9 , wherein each of the plurality of pixel circuits includes:
the organic light emitting diode having an anode and a cathode that is connected to a low power voltage; an organic light emitting diode driving block connected between the anode of the organic light emitting diode and a high power voltage and configured to control a driving current flowing through the organic light emitting diode based on the data signal applied via a data-line; a first switch configured to be turned on or off in response to a first control signal and to transfer a sensing bias voltage to the anode of the organic light emitting diode when being turned on; and a second switch configured to be turned on or off in response to a second control signal and to transfer a deterioration sensing voltage to the anode of the organic light emitting diode when being turned on, wherein, in a display mode, the first and second switches are turned off, and wherein, in the deterioration sensing mode, the first switch is turned on and the second switch is turned off during the first time, and the first switch is turned off and the second switch is turned on during the second time.

14 . The display device of claim 13 , wherein the second switch is connected between the data-line and the anode of the organic light emitting diode, and
wherein the deterioration sensing voltage is applied via the data-line during the second time of the deterioration sensing mode.

15 . The display device of claim 14 , wherein the first and second switches are implemented by p-channel metal oxide semiconductor (PMOS) transistors,
wherein the first switch is turned on when the first control signal has a low voltage level, and the second switch is turned on when the second control signal has the low voltage level, and wherein the first switch is turned off when the first control signal has a high voltage level, and the second switch is turned off when the s

Assignees

• Samsung Display Co Ltd

Inventors

• Kim Sung-Hwan

Classifications

• G09G3/3233 Primary

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

• G09G3/325 Primary

  the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver · CPC title

• G09G2310/08

  Details of timing specific for flat panels, other than clock recovery · CPC title

• G09G2330/12

  Test circuits or failure detection circuits included in a display system, as permanent part thereof · CPC title

• G09G2320/043

  Preventing or counteracting the effects of ageing · CPC title