Current sensing circuit and organic light emitting display device including the same

Patent metadata

Field	Value
Publication number	US-9984620-B2
Application number	US-201514986602-A
Country	US
Kind code	B2
Filing date	Dec 31, 2015
Priority date	Feb 4, 2015
Publication date	May 29, 2018
Grant date	May 29, 2018

Abstract

A current sensing circuit includes a first integrator configured to receive a first input current and to output a first integration signal, a second integrator configured to receive a second input current and to output a second integration signal, and a current controller configured to control at least one of the first input current and the second input current in response to the second integration signal.

First claim

What is claimed is:

1. A current sensing circuit, comprising:
a first integrator coupled to a first terminal of the current sensing circuit and configured to receive a first input current and to output a first integration signal;
a second integrator coupled to a second terminal of the current sensing circuit and configured to receive a second input current and to output a second integration signal, the first and second integrators being configured to concurrently receive respective ones of the first and second input currents;
a first variable current source coupled to an input terminal of the first integrator;
a second variable current source coupled to an input terminal of the second integrator; and
a current controller configured to control the first input current and the second input current by adjusting both an output current of the first variable current source coupled to the first integrator and an output current of the second variable current source coupled to the second integrator based on the second integration signal.

2. The current sensing circuit as claimed in claim 1 , further comprising an output unit configured to receive the first integration signal and the second integration signal, and to output a signal corresponding to a difference between the first integration signal and the second integration signal.

3. The current sensing circuit as claimed in claim 1 , wherein the output current of the first variable current source and the output current of the second variable current source are substantially the same.

4. The current sensing circuit as claimed in claim 1 , wherein the current controller is further configured to compare a value of the second integration signal with a reference value, and to increase the output current of the first variable current source and the output current of the second variable current source when the value of the second integration signal is greater than the reference value.

5. The current sensing circuit as claimed in claim 1 , wherein the first input current decreases as the output current of the first variable current source increases, and
wherein the second input current decreases as the output current of the second variable current source increases.

6. An organic light emitting display device, comprising:
a plurality of pixels coupled to a plurality of scan lines and a plurality of data lines; and
a current sensing circuit configured to receive a first sensing current and a second sensing current output from two of the data lines,
wherein the current sensing circuit comprises:
a first terminal configured to receive the first sensing current;
a second terminal configured to receive the second sensing current;
a first integrator having an input terminal coupled to the first terminal, the first integrator being configured to receive a first input current and to output a first integration signal;
a second integrator having an input terminal coupled to the second terminal, the second integrator being configured to receive a second input current and to output a second integration signal, the first and second integrators being configured to concurrently receive respective ones of the first and second input currents;
a first variable current source coupled to the input terminal of the first integrator;
a second variable current source coupled to the input terminal of the second integrator; and
a current controller configured to control the first input current and the second input current by adjusting both an output current of the first variable current source coupled to the first integrator and an output current of the second variable current source coupled to the second integrator based on the second integration signal.

7. The organic light emitting display device as claimed in claim 6 , wherein the current sensing circuit further comprises an output unit configured to receive the first integration signal and the second integration signal, and to output a signal corresponding to a difference between the first integration signal and the second integration signal.

8. The organic light emitting display device as claimed in claim 6 , wherein the output current of the first variable current source and the output current of the second variable current source are substantially the same.

9. The organic light emitting display device as claimed in claim 6 , wherein the current controller is further configured to compare a value of the second integration signal with a reference value, and to increase the output current of the first variable current source and the output current of the second variable current source when the value of the second integration signal is greater than the reference value.

10. The organic light emitting display device as claimed in claim 6 , wherein the first input current decreases as the output current of the first variable current source increases, and
wherein the second input current decreases as the output current of the second variable current source increases.

11. The organic light emitting display device as claimed in claim 6 , further comprising a multiplexer coupled to the data lines, wherein the multiplexer is configured to select the two of the data lines and to electrically connect the two of the data lines to the first terminal and the second terminal, respectively.

12. The organic light emitting display device as claimed in claim 11 , wherein each of the pixels comprises:
an organic light emitting diode;
a pixel circuit between a scan line of the plurality of scan lines, a data line of the plurality of data lines, and an anode electrode of the organic light emitting diode, and configured to control a current supplied to the organic light emitting diode; and
a sensing switch coupled between the anode electrode of the organic light emitting diode and the data line.

13. The organic light emitting display device as claimed in claim 12 , wherein each pixel circuit comprises:
a driving transistor coupled between a driving voltage supply and the anode electrode of the organic light emitting diode and having a gate electrode coupled to a first node;
a scan transistor coupled between the respective data line in the pixel circuit and the first node and having a gate electrode coupled to the scan line; and
a storage capacitor coupled between the driving voltage supply and the first node.

14. The organic light emitting display device as claimed in claim 13 , wherein the pixel circuit further comprises a control transistor coupled between the driving transistor and the organic light emitting diode.

15. The organic light emitting display device as claimed in claim 12 ,
wherein the plurality of data lines comprise a first sensing data line electrically coupled to the first terminal of the current sensing circuit and a second sensing data line electrically coupled to the second terminal of the current sensing circuit by the multiplexer,
wherein at least one of sensing switches including the sensing switch coupled to the first sensing data line is turned on, and
wherein all the sensing switches coupled to the second sensing data line are turned off.

Assignees

• Samsung Display Co Ltd

Inventors

• Lee Giljae

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

• G09G2320/0233

  Improving the luminance or brightness uniformity across the screen · CPC title

• G09G2330/12

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

• G09G3/006

  Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays (testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309) · CPC title