Array testing method and device

• US 9,230,474 B2
• Filed: 08/09/2012
• Issued: 01/05/2016
• Est. Priority Date: 03/14/2012
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Jin, Guang hai, Choi, Jae-Beom, Jung, Kwan-Wook, Lee, June-Woo, Kim, Seong-Jun
• Primary Examiner(s): Le, Vu
• Assistant Examiner(s): WOLDEMARIAM, AKLILU K
• Application Number:
  US13/570,370
• Publication Number:
  US 20130243304A1
• Time in Patent Office: 1,244 Days
• Field of Search: 382/149, 324/414, 345/76, 345/211, 345/212, 345/92, 345/77, 345/82, 345/107
• US Class Current: 1/1
• CPC Class Codes: G01R 31/2635 Testing light-emitting diodes, laser diodes or photodiodes
• CPC Class Codes: G06F 18/00 Pattern recognition
• 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 3/3225 using an active matrix

Abstract

A method for testing an array, by using an array testing device for detecting a voltage distribution formed on an array substrate, includes resetting pixel voltages of a plurality of pixel circuits formed on the array substrate with a predetermined voltage, detecting the voltage distribution of the array substrate, generating a correction value for correcting the voltage distribution of the array substrate, and measuring a threshold voltage of a driving transistor included in the plurality of pixel circuits formed on the array substrate by applying the correction value.

Claims

1. A method for testing an array substrate by using an array testing device for measuring a voltage distribution formed on the array substrate based on an optical characteristic caused by the voltage distribution, the method comprising:

resetting pixel voltages of a plurality of pixel circuits formed on the array substrate with a predetermined voltage such that the pixel voltages of the plurality of pixel circuits have a same voltage, and the array substrate has uniform voltage distribution;

measuring the uniform voltage distribution of the array substrate by the array testing device to generate a measured voltage distribution of the array substrate;

generating a correction value for calibrating the array testing device based on the uniform voltage distribution and the measured voltage distribution of the array substrate; and

measuring a threshold voltage of a driving transistor included in each of the plurality of pixel circuits formed on the array substrate by applying the correction value.

2. The method as claimed in claim 1, wherein resetting of the pixel voltages of the plurality of pixel circuits formed on the array substrate with the predetermined voltage includes resetting a pixel voltage of a second electrode of the driving transistor with a first power source voltage connected to a first electrode of the driving transistor.

3. The method as claimed in claim 2, wherein resetting of the pixel voltages of the plurality of pixel circuits formed on the array substrate with the predetermined voltage includes resetting the pixel voltages to be about 0 V by setting the first power source voltage as about 0 V.

4. The method as claimed in claim 1, wherein resetting of the pixel voltages of the plurality of pixel circuits formed on the array substrate with the predetermined voltage includes:

generating a voltage at a gate electrode of the driving transistor as a first voltage;

reducing a voltage at a second electrode of a capacitor having a first electrode connected to the gate electrode of the driving transistor, generating the first voltage to be a gate on voltage by coupling caused by the capacitor, and turning on the driving transistor; and

resetting a pixel voltage of a second electrode of the driving transistor with a first power source voltage connected to a first electrode of the driving transistor.

5. The method as claimed in claim 1, wherein measuring of the threshold voltage of the driving transistor includes generating a voltage to which the threshold voltage of the driving transistor is applied as another pixel voltage by diode-connecting the driving transistor.

6. The method as claimed in claim 5, wherein measuring of the threshold voltage of the driving transistor further includes detecting another voltage distribution of the array substrate when the voltage to which the threshold voltage of the driving transistor is applied is generated as the other pixel voltage.

17. The method as claimed in claim 1, wherein resetting of pixel voltages of the plurality of pixel circuits formed on the array substrate with the predetermined voltage includes charging a portion of each of the pixel circuits to be connected to a light emitting diode with the predetermined voltage, and the portion of each of the pixel circuits is electrically floated.

18. The method as claimed in claim 1, wherein the correction value is for correcting the measured voltage distribution of the array substrate to be substantially same with the uniform voltage distribution of the array substrate.

7. A testing device for testing an array substrate, wherein the testing device for measuring a voltage distribution formed on the array substrate based on an optical characteristic caused by the voltage distribution, the device comprising:

a light source that provides light to the array substrate, the array substrate having a uniform voltage distribution generated by resetting pixel voltages of a plurality of pixel circuits included in the array substrate with a predetermined voltage such that the pixel voltages of the plurality of pixel circuits have a same voltage, in a first array test;

a modulator that modulates an optical characteristic of light having passed through the array substrate;

a sensor that receives light modulated by the modulator and generating image information on the array substrate; and

an image processor that measures the uniform voltage distribution formed on a surface of the array substrate by analyzing the image information including an optical characteristic caused by the uniformed voltage distribution to generate a measured voltage distribution of the array substrate, wherein;

the image processor is to generate a correction value for calibrating the array testing device and to correct noise of the measured voltage distribution based on the uniform voltage distribution and the measured voltage distribution of the array substrate in the first array test, and

the testing device performs a second array test after the first array test to measure a threshold voltage of a driving transistor included in each of the plurality of pixel circuits on the array substrate by applying the correction value.

8. The device as claimed in claim 7, wherein the second array test is performed when a voltage to which the threshold voltage of the driving transistor included in the plurality of pixel circuits is applied is generated as another pixel voltage.

9. The device as claimed in claim 7, wherein the noise depends on non-uniformity of a distance between a surface of the modulator and the surface of the array substrate.

10. The device as claimed in claim 7, further comprising a first polarizer that polarizes light output by the light source in a first polarization direction and irradiates first polarized light to the array substrate.

11. The device as claimed in claim 10, further including a second polarizer that polarizes the light modulated by the modulator in a second polarization direction and irradiates second polarized light it to the sensor.

12. A method for testing an array substrate of a display device by using an array testing device for measuring a voltage distribution formed on the array substrate based on an optical characteristic caused by the voltage distribution, the array substrate including a plurality of pixels each having a switching transistor for transmitting a data signal, a capacitor connected between the switching transistor and a driving transistor, and a compensation transistor connected between a gate electrode and a drain electrode of the driving transistor, the method comprising:

resetting pixel voltages of the plurality of pixels with a predetermined voltage such that the pixel voltages of the plurality of pixels have a same voltage, and the array substrate has a uniform voltage distribution;

measuring the uniform voltage distribution of the pixels by the array testing device to generate a measured voltage distribution of the pixels;

generating a correction value for calibrating the array testing device based on the uniform voltage distribution and the measured voltage distribution of the pixels; and

measuring threshold voltages of the driving transistors of the plurality of pixels by applying the correction value.

13. The method as claimed in claim 12, wherein resetting of the pixel voltages of each of the plurality of pixels with the predetermined voltage includes:

supplying a data signal of a first level to a first electrode of the capacitor while the switching transistor is turned on;

turning on the compensation transistor, and controlling a power source voltage connected to a source electrode of the driving transistor to have a second level;

turning off the compensation transistor;

supplying a data signal of a second level to the first electrode of the capacitor; and

turning on the driving transistor, and resetting the pixel voltages with the power source voltage.

14. The method as claimed in claim 12, wherein resetting of the pixel voltages of each of the plurality of pixels with the predetermined voltage includes:

turning on the switching transistor and supplying a data signal of a first level to a first electrode of the capacitor while a power source voltage connected to a source electrode of the driving transistor is maintained at the first level;

turning on the compensation transistor; and

resetting the pixel voltages and the gate electrode of the driving transistor with the power source voltage.

15. The method as claimed in claim 12, wherein measuring of each of the threshold voltages of the driving transistors includes turning on the compensation transistor, controlling a power source voltage to have a first level, and generating voltages to which the threshold voltages of each of the driving transistors are applied as other pixel voltages.

16. The method as claimed in claim 15, wherein measuring of each of the threshold voltages of the driving transistors further includes detecting another voltage distribution of the plurality of pixels while the voltages to which the threshold voltages of each of the driving transistors are applied are generated to be the other pixel voltages.