Apparatus and method for testing pixels of flat panel display

• US 7,012,583 B2
• Filed: 02/07/2003
• Issued: 03/14/2006
• Est. Priority Date: 02/07/2003
• Status: Expired due to Fees

• Current Assignee: Shimadzu Corporation
• Original Assignee: Shimadzu Corporation
• Inventors: Baker, David, Toro-Lira, Guillermo
• Primary Examiner(s): Shankar, Vijay
• Assistant Examiner(s): DHARIA, PRABODH M
• Application Number:
  US10/360,223
• Publication Number:
  US 20040155838A1
• Time in Patent Office: 1,131 Days
• Field of Search: 345/904, 345/75, 345/74.1, 345/75.2, 324/765, 324/751, 324/770, 324/501, 257/66, 250/221
• US Class Current: 345/75.2
• CPC Class Codes: G01R 31/305 using electron beams investigating or analysing materials by measuring photoelectric effect G01N23/227
• 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 3/3611 Control of matrices with row and column drivers

Abstract

An apparatus for testing pixels of a flat panel display has a palette for holding a TFT substrate, drive signal source units, and predetermined voltage source units. The palette is grounded. One of the predetermined voltage source units applies a predetermined voltage to a Cs electrode of each of pixels constituting the TFT substrate so that the predetermined voltage is used as a reference voltage of the TFT substrate 11. The drive signal source units supply drive signals to a gate electrode G and a source electrode S respectively in each of the pixels constituting the TFT substrate. The voltages of the drive signals are floated by predetermined voltages given by the corresponding predetermined voltage source units respectively.

Claims

1. An apparatus for testing pixels of a flat panel display, comprising:

an electron beam source for irradiating said flat panel display with an electron beam;

a secondary electron detector for detecting secondary electrons emitted from each of said pixels of said flat panel display irradiated with said electron beam;

a holding member for holding said flat panel display; and

a voltage source unit for applying a first predetermined voltage to either said holding member or an electrode of a storage capacitor contained in each pixel in a condition that a reference voltage of said pixel is applied to said electrode of said storage capacitor, so as to reduce a voltage difference between the holding member and the pixel.

2. The apparatus for testing pixels of a flat panel display according to claim 1, wherein said voltage source unit applies said first predetermined voltage as a plus value to said electrode of said storage capacitor.

3. The apparatus for testing pixels of a flat panel display according to claim 2, wherein said voltage source unit applies said first predetermined voltage as a plus value to a data signal input terminal of a transistor contained in each pixel and to a switching control signal input terminal of said transistor.

4. The apparatus for testing pixels of a flat panel display according to claim 1, wherein said voltage source unit applies said first predetermined voltage as a minus value to said holding member.

5. The apparatus for testing pixels of a flat panel display according to claim 1, further comprising:

a filter which is provided in a trajectory of secondary electrons emitted from said pixel and to which a second predetermined voltage is applied;

wherein said voltage source unit further applies said first predetermined voltage to said filter.

10. The apparatus for testing pixels of a flat panel display according to claim 1, wherein the holder comprises a palette for supporting the flat panel display and a prober for supplying drive signals to each pixel.

6. A method of testing pixels of a flat panel display, comprising:

holding said flat panel display by a holding member;

applying a first predetermined voltage to either said holding member or an electrode of a storage capacitor contained in each of said pixels in a condition that a reference voltage of said pixel is applied to said electrode of said storage capacitor, so as to reduce a voltage difference between the holding member and the pixel;

irradiating said flat panel display with an electron beam; and

detecting secondary electrons emitted from each of said pixels of said flat panel display irradiated with said electron beam.

7. The method of testing pixels of a flat panel display according to claim 6, wherein the predetermined voltage applying step applies said first predetermined voltage as a plus value to said electrode of said storage capacitor.

8. The method of testing pixels of a flat panel display according to claim 7, wherein the predetermined voltage applying step applies said first predetermined voltage as a plus value to a data signal input terminal of a transistor contained in each of said pixels and to a switching control signal input terminal of said transistor.

9. The method of testing pixels of a flat panel display according to claim 6, wherein the predetermined voltage applying step applies said first predetermined voltage as a minus value to said holding member.

12. The method of testing pixels of a flat panel display according to claim 6, further comprising a step of removing secondary electrons below a predetermined energy indicating noise from being detected by the secondary electron detector, thereby improving pixel voltage waveform contrast and improving detection of pixel defect.

11. An apparatus for testing pixels of a flat panel display, comprising:

an electron beam source for irradiating said flat panel display with an electron beam;

a secondary electron detector for detecting secondary electrons emitted from each of said pixels of said flat panel display irradiated with said electron beam;

a holding member for holding said flat panel display;

a voltage source unit for applying a first predetermined voltage to either said holding member or an electrode of a storage capacitor contained in each pixel in a condition that a reference voltage of said pixel is applied to said electrode of said storage capacitor, so as to reduce a voltage difference between the holding member and the pixel; and

a filter which is provided in a trajectory of secondary electrons emitted from said pixel and to which a second predetermined voltage is applied;

wherein said voltage source unit further applies said first predetermined voltage to said filter;

wherein the filter comprises a grid that removes secondary electrons below a predetermined energy indicating noise from being detected by the secondary electron detector, thereby improving pixel voltage waveform contrast and improving detection of pixel defect.