Electroluminescent display and method of sensing electrical characteristics of electroluminescent display

• US 10,460,662 B2
• Filed: 11/03/2017
• Issued: 10/29/2019
• Est. Priority Date: 11/28/2016
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Song, Eunji, Son, Kiwon, Shin, Hunki, Kim, Dongik
• Primary Examiner(s): Li, Lin
• Application Number:
  US15/802,877
• Publication Number:
  US 20180151112A1
• Time in Patent Office: 725 Days
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0264 Details of driving circuits
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 2370/08 Details of image data interface between the display device controller and the data line driver circuit
• CPC Class Codes: G09G 3/006 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 Class Codes: G09G 3/2096 Details of the interface to the display terminal specific for a flat panel suitable for both CRT and flat panel G09G5/006; specific for a CRT G09G1/167
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/325 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 Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements
• 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

Abstract

An electroluminescent display and a method of sensing electrical characteristics of the electroluminescent display are disclosed. The electroluminescent display includes a display panel including a plurality of pixels, a plurality of gate lines, and a plurality of data lines and a driver integrated circuit connected to the data line through a channel terminal. The driver integrated circuit includes a data voltage generator configured to generate a data voltage to be supplied to the pixel, a first switch connected between the channel terminal and the data voltage generator, a sensor configured to sense electrical characteristics of the pixel, and a second switch connected between the channel terminal and the sensor.

Claims

1. An electroluminescent display comprising:

a display panel including a plurality of pixels, a plurality of gate lines, and a plurality of data lines; and

a driver integrated circuit connected to the data line through a channel terminal,

wherein the driver integrated circuit includes;

a data voltage generator configured to generate a data voltage to be supplied to the pixel;

a first switch connected between the channel terminal and the data voltage generator;

a sensor configured to sense electrical characteristics of the pixel; and

a second switch connected between the channel terminal and the sensor,

wherein each pixel includes;

a driving thin film transistor (TFT) including a control electrode connected to a first node, a first electrode connected to a high potential driving power, and a second electrode connected to a second node;

an organic light emitting diode (OLED) connected between the second node and a low potential driving power;

a first switching TFT including a control electrode connected to a first gate line supplied with a first gate signal, a first electrode connected to the data line, and a second electrode connected to the first node;

a second switching TFT including a control electrode connected to a second gate line supplied with a second gate signal, a first electrode connected to the data line, and a second electrode connected to the second node; and

a storage capacitor connected between the high potential driving power and the first node,

wherein during a degradation tracking period following a first programming period, the first and second switches are turned off, and the first and second switching TFTs are turned on.

2. The electroluminescent display of claim 1, wherein during the first programming period, the first switch, the first switching TFT, and the second switching TFT are turned on, and the second switch is turned off,

wherein during a second programming period following the degradation tracking period, the first switch and the second switching TFT are turned on, and the second switch and the first switching TFT are turned off, and

wherein during a sensing period following the second programming period, the second switch and the second switching TFT are turned on, and the first switch and the first switching TFT are turned off.

3. The electroluminescent display of claim 2, wherein the data voltage generator supplies a first data voltage to the data line during the first programming period and the degradation tracking period, and supplies a second data voltage higher than the first data voltage to the data line during the second programming period.

4. The electroluminescent display of claim 3, wherein a difference between a voltage of the high potential driving power and the first data voltage is greater than a threshold voltage of the driving TFT.

5. The electroluminescent display of claim 4, wherein a voltage of the data line increases in proportional to a degradation of the OLED during the degradation tracking period, and

wherein during the sensing period, a rising slope of the voltage of the data line is less after the degradation of the OLED than before the degradation of the OLED.

6. The electroluminescent display of claim 1, wherein the driving TFT, the first switching TFT, and the second switching TFT are implemented as p-type metal-oxide semiconductor (PMOS) transistors.

7. A method of sensing electrical characteristics of an electroluminescent display including a driver integrated circuit having a first switch and a second switch, and a plurality of pixels each including a driving thin film transistor (TFT) including a control electrode connected to a first node, a first electrode connected to a high potential driving power, and a second electrode connected to a second node, an organic light emitting diode (OLED) connected between the second node and a low potential driving power, a first switching TFT including a control electrode connected to a first gate line supplied with a first gate signal, a first electrode connected to a data line, and a second electrode connected to the first node, a second switching TFT including a control electrode connected to a second gate line supplied with a second gate signal, a first electrode connected to the data line, and a second electrode connected to the second node, and a storage capacitor connected between the high potential driving power and the first node, the method comprising:

during a first programming period, applying a first data voltage to the first node and the second node through a data line to turn on the driving TFT;

during a degradation tracking period following the first programming period, applying a driving current to the OLED from the driving TFT to set a voltage of the second node depending on a degradation of the OLED;

during a second programming period following the degradation tracking period, applying a second data voltage higher than the first data voltage to the second node through the data line; and

during a sensing period following the second programming period, reading out a change in the voltage of the second node, which decreases depending on the driving current, through the data line,

wherein during the degradation tracking period, the first and second switches are turned off, and the first and second switching TFTs are turned on.

8. The method of claim 7, wherein a voltage of the data line connected to the second node increases in proportional to the degradation of the OLED during the degradation tracking period, and

wherein during the sensing period, a rising slope of the voltage of the data line connected to the second node is less after the degradation of the OLED than before the degradation of the OLED.

9. A method of sensing electrical characteristics of an electroluminescent display including a driver integrated circuit having a first switch and a second switch, and a plurality of pixels each including a driving thin film transistor (TFT) including a control electrode connected to a first node, a first electrode connected to a high potential driving power, and a second electrode connected to a second node, and an organic light emitting diode (OLED) connected between the second node and a low potential driving power, a first switching TFT including a control electrode connected to a first gate line supplied with a first gate signal, a first electrode connected to a data line, and a second electrode connected to the first node, a second switching TFT including a control electrode connected to a second gate line supplied with a second gate signal, a first electrode connected to the data line, and a second electrode connected to the second node, and a storage capacitor connected between the high potential driving power and the first node, the method comprising:

during an initialization period, applying a data voltage higher than a threshold voltage of the OLED to the second node through the data line to initialize the second node by turning on the first switch and the second switching TFT and turning off the second switch and the first switching TFT; and

during a sensing period following the initialization period, reading out a change in a voltage of the second node, which decreases as the data voltage is discharged through the OLED, through the data line by turning on the second switch and the second switching TFT and turning off the first switch and the first switching TFT.

10. The method of claim 9, wherein during the sensing period, a falling slope of a voltage of the data line connected to the second node is less after a degradation of the OLED than before the degradation of the OLED.