CN111665260A - Display panel inspection device - Google Patents

Display panel inspection device Download PDF

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CN111665260A
CN111665260A CN201911308754.2A CN201911308754A CN111665260A CN 111665260 A CN111665260 A CN 111665260A CN 201911308754 A CN201911308754 A CN 201911308754A CN 111665260 A CN111665260 A CN 111665260A
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display panel
display
reference pattern
camera
phase
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CN111665260B (en
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李相允
姜声镛
李贤植
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Intekplus Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8806—Specially adapted optical and illumination features
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
    • G01N2021/8887—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges based on image processing techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N2021/9513—Liquid crystal panels
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/063—Illuminating optical parts
    • G01N2201/0636—Reflectors

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  • Chemical & Material Sciences (AREA)
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  • General Health & Medical Sciences (AREA)
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  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Signal Processing (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
  • Electroluminescent Light Sources (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Testing Of Optical Devices Or Fibers (AREA)

Abstract

The present invention relates to a display panel inspection apparatus. The display generates a periodic reference pattern, and irradiates the surface of the display panel to be inspected with an incident angle larger than a critical angle of total reflection. The camera acquires an image reflected from the surface of the display panel in a state where the reference pattern is irradiated to the surface of the display panel. The controller sequentially acquires images through the camera while phase-shifting the reference pattern by a predetermined angle each time in one period through the display, and then calculates a phase and a tilt with respect to the surface of the display panel based on the acquired images, thereby discriminating whether the surface of the display panel is defective.

Description

Display panel inspection device
Technical Field
The present invention relates to a display panel inspection apparatus, and more particularly, to an apparatus for inspecting an appearance defect of a display panel.
Background
In general, display panels are widely used for smart phones, notebook computers, televisions, computer monitors, and the like. Such Display panels include LCD (Liquid Crystal Display) panels, OLED (Organic light emitting Diode) panels, and the like.
On the other hand, appearance defects such as scratches (scratch), cracks (crack), chipping (chipping), and the like may occur on the surface of the display panel during the production process of the display panel. In particular, the OLED panel is composed of a flexible substrate, and has low hardness, so that an appearance defect such as a dent (dent) may occur even when the surface is pressed. Therefore, a process for inspecting the appearance defect of the display panel is performed at the production site of the display panel.
However, in the case where a technician checks with the naked eye in the past, there are problems as follows: since the reliability of inspecting the defect is lowered due to individual differences in the proficiency of the worker, etc., and the worker intensively works for a long time in order to inspect the defect to cause eye fatigue, productivity is lowered.
Disclosure of Invention
(problem to be solved)
The invention provides a display panel inspection device, which can automatically detect the appearance defects of a display panel, improve the productivity and improve the reliability of the detected defects.
(means for solving the problems)
The display panel inspection apparatus of the present invention for achieving the above object includes: display, camera and controller. The display generates a periodic reference pattern, and irradiates the surface of the display panel to be inspected with an incident angle larger than a critical angle of total reflection. The camera acquires an image reflected from the surface of the display panel in a state where the reference pattern is irradiated to the surface of the display panel. The controller sequentially acquires images through the camera while phase shifting (phase shifting) the reference pattern by a predetermined angle each time in one period through the display, and then calculates a phase and a gradient with respect to the surface of the display panel based on the acquired images, thereby discriminating whether the surface of the display panel is defective.
Here, the controller sequentially acquires four images through the camera while phase-shifting the reference pattern by 90 ° each time through the display.
Then, the display panel inspection apparatus includes a mirror that receives the light reflected from the surface of the display panel to reflect to the camera. The camera may be configured to receive light reflected by the mirror.
(Effect of the invention)
The invention can automatically detect the appearance defects of the display panel, and has the effects of improving the productivity and improving the reliability of the detected defects.
Drawings
Fig. 1 is a structural diagram of a display panel inspection apparatus according to an embodiment of the present invention.
Fig. 2 is a block diagram illustrating a part of the display panel inspection apparatus of fig. 1.
Fig. 3 is a perspective view of fig. 2.
Fig. 4 is a photograph showing an example of images sequentially acquired while phase-shifting the reference pattern by 90 ° each time.
Fig. 5 is a photograph showing a phase image and a gradient image obtained based on the image of fig. 4.
(description of reference numerals)
10: display panel
110: display device
111: reference pattern
120: camera head
140: mirror
130: controller
Detailed Description
The present invention is described in detail below with reference to the accompanying drawings. Here, the same reference numerals are used for the same components, and repetitive description is omitted, so that detailed description of known functions and configurations which may make the gist of the present invention unclear is omitted. Embodiments of the present invention are provided so that this disclosure will be more fully informed by those having ordinary skill in the art. Therefore, the shapes, sizes, and the like of the members may be exaggerated in the drawings for the purpose of more clear description.
Fig. 1 is a structural diagram of a display panel inspection apparatus according to an embodiment of the present invention. Fig. 2 is a block diagram illustrating a part of the display panel inspection apparatus of fig. 1. Fig. 3 is a perspective view of fig. 2.
Referring to fig. 1 to 3, a display panel inspection apparatus 100 according to an embodiment of the present invention includes: display 110, camera 120, and controller 130.
The display 110 generates a periodic reference pattern 111 to be irradiated on the surface of the display panel 10 as an inspection object. Here, the display panel 10 may be an OLED panel, but may also be an LCD panel or the like. In the case where the display panel 10 is mounted on the XY horizontal plane of the inspection stage 101 in a state where the surface to be inspected is directed upward, the display 110 may be configured to irradiate the reference pattern 111 at a set incident angle on the upper side of the display panel 10. The inspection table 101 may be secured to and supported by the inspection frame 102 and the display 110 may be secured to and supported by the inspection frame 102.
The reference pattern 111 may be configured in a form in which relatively bright bands and relatively dark bands are alternately arranged. The bright and dark bands have a predetermined period, respectively. The display 110 is constituted by a flat display device such as an LCD device or an OLED device, and the reference pattern 111 is irradiated to the entire surface of the display panel 10 in the form of a surface light source. The display 110 is controlled by the controller 130 to phase-shift the reference pattern 111 by a predetermined angle each time in one period when the surface of the display panel 10 is subjected to the appearance inspection.
The display panel 10 is configured to transmit light through a surface, and thus it is necessary that the reference pattern 111 incident from the display 110 to the surface of the display panel 10 be totally reflected to be provided to the camera 120. For this, the display 110 irradiates the reference pattern 111 on the surface of the display panel 10 at an incident angle α greater than a critical angle of total reflection. The larger the incident angle α of the reference pattern 111, the better the total reflection of the reference pattern 111 can be achieved, but the Footprint (Footprint) of the display panel inspection apparatus 100 may be increased. If the display panel 10 is an OLED panel, the incident angle α of the reference pattern 111 may be set to 55 to 57 °.
The camera 120 acquires an image reflected from the surface of the display panel 10 in a state where the reference pattern 111 is irradiated to the surface of the display panel 10. When the reference pattern 111 is irradiated on the surface of the display panel 10, the reference pattern 111 may be deformed by the influence of the surface shape of the display panel 10. The camera 120 acquires an image of the deformed reference pattern, and can determine the surface shape of the display panel 10 in reverse.
The camera 120 may be a CCD camera (charge-coupled device camera) or the like. A CCD camera is a device that converts an image into an electric signal using a Charge Coupled Device (CCD). The camera 120 may receive light reflected from the surface of the display panel 10 through a lens.
The camera 120 may be disposed at one side of the display panel 10 together with the display 110 to minimize the footprint of the display panel inspection apparatus 100. For example, if the display 110 is disposed on the left side of the display panel 10, the camera 120 may be disposed higher than the display 100 on the left side of the display panel 10. In this case, the light reflected from the surface of the display panel 10 received by the mirror 140 may be reflected to the camera 120.
The mirror 140 is disposed on the opposite side of the display 110, and the display panel 10 is disposed between the mirror 140 and the display 110. The mirror 140 can be vertically disposed in a state where the reflection surface faces the display 110 side. The mirror 140 may be fixed and supported to the inspection frame 102. The camera 120 may be configured to receive light reflected by the mirror 140. The camera 120 may be fixed to the inspection frame 102 by a bracket or the like in a state where the light receiving axis is inclined at a set angle β with respect to the horizontal plane. If the incident angle α of the reference pattern 111 is 56 °, the light receiving axis angle β of the camera 120 may be 34 °.
The controller 130 sequentially acquires images through the camera 120 while phase-shifting (phaseshifting) the reference pattern 111 by a predetermined angle each time in one cycle through the display 110, and then calculates a phase shift and a tilt for the surface of the display panel 10 based on the acquired images, thereby discriminating whether the surface of the display panel 10 is defective.
If there are appearance defects such as scratches, cracks, chipping, etc. on the surface of the display panel 10, appearance defect regions may occur in the phase image and the inclination image that are calculated by the controller 130. The controller 130 processes the phase image and the inclination image to recognize whether the surface of the display panel 10 is defective.
For example, the controller 130 may detect the apparent defect region using a labeling (labeling) technique with respect to the phase image and the inclination image. Labeling is a method of searching for all pixels of an image and distinguishing each object by a number method using a connection relationship such as four-connected (4-connected) or eight-connected (8-connected).
The controller 130 distinguishes the background region and the apparent defect region based on the phase image data and the inclination data obtained by labeling, by which the apparent defect region can be detected. If the apparent defect area is detected, the controller 130 determines that the surface of the display panel 10 has a defect. At this time, if the apparent defect region is detected from both the phase image data AND the inclination image data through the AND calculation, the controller 130 may determine that there is a defect on the surface of the display panel 10. The controller 130 may be constituted by at least one program that can execute a control program.
On the other hand, the controller 130 may sequentially acquire four images through the camera 120 while phase-shifting the reference pattern 111 by 90 ° each time through the display 110. For example, in the case where the controller 130 sequentially acquires four images through the camera 120 while phase-shifting the reference pattern 111 by 90 ° each time through the display 110, the brightness values of the four images are as shown in mathematical formula 1 below:
(math formula 1)
I1(x，y)＝I0(x，y){1+γ(x，y)cos[φ(x，y)]}
Figure BDA0002323918240000061
I3(x，y)＝I0(x，y){1+γ(x，y)cos[φ(x，y)+π]}
Figure BDA0002323918240000062
Here, x and y are spatial variables (spatial variables). I is0(x, y) is an average luminance value of the reference pattern. Visibility (visibility) of γ (x, y) reference pattern. Phi (x, y) is the phase value to be measured. The finger of phi (x, y) + moves the reference pattern by about every time, i.e. by 90 deg..
Transforming I as brightness values of four images shown in the above mathematical formula 1 by calculation of trigonometric function equivalent values1(x，y),I2(x，y),I3(x，y),I4(x, y) and then solving the simultaneous equations, the following equations can be obtained2, obtaining the phase phi (x, y) of each point on the surface of the display panel:
(math figure 2)
Figure BDA0002323918240000071
The inclination can be found by substituting the phase Φ (x, y) found as described above into the following equation 3 representing the relationship between the phase and the inclination:
(math figure 3)
Figure BDA0002323918240000072
Figure BDA0002323918240000073
In this case, the amount of the solvent to be used,
Figure BDA0002323918240000074
the x-axis and y-axis inclinations of the local position (i, j), respectively, h is the data interval, and N is the data number.
For example, in the case where the surface of the display panel 10 has an appearance defect, if the controller 130 sequentially acquires four images by the camera 120 while phase-shifting the reference pattern 111 by 90 ° each time through the display 110, the acquired images may be as shown in (a), (b), (c), and (d) of fig. 4.
If the controller 130 calculates the phase and the inclination with respect to the surface of the display panel 10 based on the acquired image, a phase image may be obtained as in (a) of fig. 5 and an inclination image may be obtained as in (b) of fig. 5. As shown in fig. 5 (a) and (b), it was confirmed that a defect region (DZ) occurred in the phase image and the tilt image. The controller 130 processes the phase image and the inclination image as in the above example to recognize whether the surface of the display panel 10 is defective.
As described above, with the display panel inspection apparatus 100 of the present embodiment, the detection of the appearance defect of the display panel 10 is automated, the productivity can be improved, and the reliability of detecting the defect can be improved.
The invention has been described with reference to an embodiment shown in the drawings, which are intended to be exemplary only, and it is to be understood that various modifications and equivalent other embodiments may be devised by those skilled in the art. Accordingly, the true scope of the invention should be defined only by the claims.

Claims (3)

1. A display panel inspection apparatus, comprising:
a display for generating a periodic reference pattern and irradiating the surface of a display panel to be inspected with an incident angle larger than a critical angle of total reflection;
a camera which acquires an image reflected from the surface of the display panel in a state where a reference pattern is irradiated to the surface of the display panel; and
and a controller which sequentially acquires images through the camera while phase-shifting the reference pattern by a predetermined angle each time in one period through the display, and then calculates a phase and a tilt for the surface of the display panel based on the acquired images, thereby discriminating whether the surface of the display panel is defective.
2. The display panel inspection apparatus according to claim 1,
the controller obtains four images in sequence through the camera while shifting the phase of the reference pattern by 90 degrees each time through the display.
3. The display panel inspection apparatus according to claim 1, comprising:
a mirror to receive light reflected from the display panel surface to reflect to the camera.
CN201911308754.2A 2019-03-07 2019-12-18 Display panel inspection device Active CN111665260B (en)

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Publication number Priority date Publication date Assignee Title
US20070091319A1 (en) * 2004-06-04 2007-04-26 Asahi Glass Company, Limited Method and apparatus for inspecting front surface shape
CN102169095A (en) * 2009-09-24 2011-08-31 凯德易株式会社 Inspecting system and inspecting method
KR20110087551A (en) * 2010-01-26 2011-08-03 주식회사 고영테크놀러지 Image sensing system and method
JP2014020870A (en) * 2012-07-17 2014-02-03 Kurabo Ind Ltd Surface shape inspection device and surface shape inspection method
TW201741779A (en) * 2016-03-01 2017-12-01 Ａｓｍｌ荷蘭公司 Method and apparatus to determine a patterning process parameter
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KR20200107404A (en) 2020-09-16

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