Method of inspecting defect for electroluminescence display apparatus, defect inspection apparatus, and method of manufacturing electroluminescence display apparatus using defect inspection method and apparatus

• US 8,493,296 B2
• Filed: 09/04/2007
• Issued: 07/23/2013
• Est. Priority Date: 09/04/2006
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Sanyo Semiconductor Company Limited (ON Semiconductor Corporation), Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Inventors: Ogawa, Takashi
• Primary Examiner(s): Awad, Amr
• Assistant Examiner(s): BRAY, STEPHEN A
• Application Number:
  US11/849,825
• Publication Number:
  US 20080055211A1
• Time in Patent Office: 2,149 Days
• Field of Search: 345 76- 83, 324/414, 324/770, 32476001-76002, 324/762.07, 324/762.09, 445 1- 3, 445 60- 63
• US Class Current: 345/77
• 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
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

A dark spot defect of an EL element is detected based on an emission brightness or a current flowing through the EL element when an element driving transistor which controls a drive current to be supplied to the EL element is operated in its linear operating region and the EL element is set to an emission level. A dim spot defect caused can be detected based on a current flowing through the EL element when the element driving transistor is operated in its saturation operating region and the EL element is set to the emission level. When an abnormal display pixel is detected based on an emission brightness, a pixel which is determined as an abnormal display pixel and which is not determined as a dark spot defect is determined, and the pixel is detected as a dim spot defect caused by the characteristic variation of the element driving transistor.

Claims

1. A method of inspecting a defect for an electroluminescence display apparatus, wherein

the display apparatus comprises, in each pixel, an electroluminescence element and an element driving transistor which is connected to the electroluminescence element and which controls a current flowing through the electroluminescence element, the method comprising:

supplying a first inspection ON display signal, which sets the electroluminescence element to an emission level, to each pixel;

operating the element driving transistor in a saturation operating region of the transistor;

observing an emission state of the electroluminescence element;

identifying a pixel having an emission brightness which is smaller than a reference brightness as an abnormal display defect pixel while the element driving transistor is operated in a saturation operating region of the transistor;

supplying a second inspection ON display signal, which sets the electroluminescence element to an emission level, to each pixel;

operating the element driving transistor in a linear operating region of the transistor;

observing an emission state of the electroluminescence element;

identifying a non-emission pixel as a dark spot defect pixel caused by the electroluminescence element; and

identifying a pixel which is identified as the abnormal display defect pixel and which is not identified as the dark spot defect pixel as a dim spot defect pixel caused by the element driving transistor.

2. The method of inspecting a defect for an electroluminescence element according to claim 1, wherein

the detection of the dark spot defect pixel is executed after a reverse bias voltage is applied to the electroluminescence element of each pixel.

3. A method of manufacturing an electroluminescence display apparatus, wherein

a laser repairing is executed, on the dark spot defect pixel detected by the defect inspection method according to claim 1, in which laser light is selectively irradiated on a short-circuited region between an anode and a cathode of the electroluminescence element of the pixel and a current path in the short-circuited region is cut.

4. A method of manufacturing an electroluminescence display apparatus, wherein

ultraviolet light is irradiated, on the dim spot defect pixel detected by the inspection method according to claim 1, while a predetermined bias is applied to the element driving transistor of the pixel, to repair a shift of a current supplying characteristic of the element driving transistor.

5. A defect inspection apparatus for an electroluminescence display apparatus which comprises, in each pixel, an electroluminescence element having a diode structure and an element driving transistor which is connected to the electroluminescence element and which controls a current flowing through the electroluminescence element, the defect inspection apparatus comprising:

a power supply generation section which generates a plurality of power supplies to be supplied to each pixel during defect inspection;

a power supply switching section which switches a power supply to be supplied to the pixel in order to switch and control an operation of the element driving transistor in a saturation operating region and in a linear operating region according to a defect inspection mode;

an inspection signal generation section which generates an inspection timing signal and an inspection ON display signal;

an emission detecting section which detects an emission state of the electroluminescence element; and

a defect determining section, wherein

in an abnormal display inspection mode,

with a power supply for dim spot inspection selected by the power supply switching section and the timing signal, the element driving transistor is operated in a saturation operating region of the transistor and an inspection ON display signal which sets the electroluminescence element to an emission level is supplied to a corresponding pixel,

the emission detecting section detects an emission brightness of the electroluminescence element, and

the defect determining section compares the detected emission brightness to a reference brightness and determines a pixel having the emission brightness which is smaller than the reference brightness as an abnormal display defect pixel,

in a dark spot inspection mode,

with a power supply for dark spot inspection selected by the power supply switching section and the timing signal, the element driving transistor is operated in a linear operating region of the transistor and a dark spot inspection ON display signal which sets the electroluminescence element to an emission level is supplied to a corresponding pixel,

the emission detecting section detects an emission brightness of the electroluminescence element, and

the defect determining section compares the detected emission brightness to a reference brightness and determines a pixel having the emission brightness which is smaller than the reference brightness as a dark spot defect pixel caused by the electroluminescence element, and

in a dim spot inspection mode, the defect determining section determines a pixel which is detected as the abnormal display defect pixel and which is not detected as the dark spot defect pixel as a dim spot defect pixel caused by the element driving transistor.