Method of inspecting organic electroluminescence display device

• US 8,687,874 B2
• Filed: 10/24/2012
• Issued: 04/01/2014
• Est. Priority Date: 04/27/2010
• Status: Active Grant

• Current Assignee: JDI Design and Development GK
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Hiraoka, Tomomi
• Primary Examiner(s): Werner, Brian P
• Application Number:
  US13/659,084
• Publication Number:
  US 20130044937A1
• Time in Patent Office: 524 Days
• Field of Search: None
• US Class Current: 382/149
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2360/147 the originated light output being determined for each pixel
• 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 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: H10K 71/00 Manufacture or treatment specially adapted for the organic devices covered by this subclass
• CPC Class Codes: H10K 71/861 Repairing

Abstract

A method of inspecting an organic electroluminescence (EL) display device which includes pixels each of which includes an organic electroluminescence (EL) element includes: imaging the pixels for a predetermined time with a reverse bias voltage being applied to the pixels; identifying light emitting points which produce, in the imaging, light leakage that is greater than or equal to threshold intensity, the light emitting points being located within the pixels; and determining that a pixel including one light emitting point is a defective pixel when, after plural iterations of the imaging and the identifying, the light emitting point is identified in twice or more in the plural iterations of the identifying.

Claims

1. A method of inspecting an organic electroluminescence (EL) display device which includes pixels each of which includes an organic EL element, the method comprising:

imaging the pixels for a predetermined time with a reverse bias voltage being applied to the pixels;

identifying light emitting points which produce, in the imaging, luminance of light leakage that is greater than or equal to threshold intensity, the light emitting points being located within the pixels; and

determining that a pixel including a one of the light emitting points is a defective pixel when, after plural iterations of the imaging and the identifying, the one light emitting point is identified twice or more in the plural iterations of the identifying,

wherein the threshold intensity is set based on average luminance of the pixels that is obtained by imaging simultaneous light emission from all the pixels in the imaging.

2. The method of inspecting an organic EL display device according to claim 1,

wherein a value of the reverse bias voltage is constant for the predetermined time for imaging the pixels in the imaging.

3. The method of inspecting an organic EL display device according to claim 2,

wherein the value of the reverse bias voltage applied to the pixels is kept unchanged from a start of a first iteration of the imaging to an end of a final iteration of the imaging in the plural iterations of the imaging.

4. The method of inspecting an organic EL display device according to claim 1,

wherein, in the imaging, application of the reverse bias voltage to the pixels and imaging of the pixels are synchronized.

5. The method of inspecting an organic EL display device according to claim 1,

wherein the predetermined time for imaging the pixels in the imaging varies from 5 seconds to 60 seconds.

6. The method of inspecting an organic EL display device according to claim 1,

wherein the imaging and the identifying are each repeated from 3 to 10 times.

7. The method of inspecting an organic EL display device according to claim 1,

wherein in the imaging, imaging is performed by a cooled charge coupled device (CCD) camera, and

in the identifying, the light emitting points which produce light leakage are identified based on an image obtained from the imaging.

8. The method of inspecting an organic EL display device according to claim 1,

wherein when the one light emitting point is identified twice or more in the plural iterations of the identifying and the one light emitting point is not identified in the final iteration of the identifying in the plural iterations of the identifying,

in the determining, the pixel including the light emitting point is determined as a defective pixel.

9. The method of inspecting an organic EL display device according to claim 1,

wherein in the imaging, the average luminance of the pixels is calculated as an average value of noise by imaging simultaneous light emission from all the pixels, and

in the identifying, from an image obtained by imaging light emitted from the pixels or part of the pixels, a light emitting point producing light emission that is greater than or equal to the threshold intensity is identified as a light emitting point producing light leakage, the threshold intensity being a value obtained by adding a predetermined offset value to the average value of noise.