KR102037050B1 - Vision testing system for display device and inspecting method thereof - Google Patents

Abstract

The present invention relates to an inspection apparatus for a display device, and more particularly, to a vision inspection system of a display device and an inspection method thereof.
A feature of the present invention is to apply electrical signals to a liquid crystal panel or a modular liquid crystal display device by applying an electrical signal to automate a vision inspection to detect defects through high resolution image acquisition, thereby speeding up the inspection process more quickly and accurately. It can proceed and improve the reliability of the inspection process.
In addition, the method further includes a foreign material detection process, and precisely distinguishes the fine dust accumulated on the surface of the liquid crystal panel or the modular liquid crystal display device and the defects of specific pixels (PD; Point Defect). The problem that the liquid crystal panel or the modular liquid crystal display device is disposed of by the fine dust can be prevented from occurring, thereby increasing productivity and lowering manufacturing cost.

Description

Vision testing system for display device and inspecting method

The present invention relates to an inspection apparatus for a display device, and more particularly, to a vision inspection system of a display device and an inspection method thereof.

In recent years, as the society enters a full-scale information age, a display field for processing and displaying a large amount of information has been rapidly developed, and various various flat panel display devices have been developed and are in the spotlight.

Specific examples of such a flat panel display device include a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), and an electroluminescent display device. (Electroluminescence Display device: ELD), etc. These flat panel display devices are rapidly replacing the existing cathode ray tube (CRT) by showing excellent performance of thin, light weight, low power consumption.

Among them, liquid crystal display devices are used in various fields such as laptops, monitors, and TVs because of their high contrast ratio, suitable for moving picture display, and low power consumption. The principle of image realization is the optical anisotropy of liquid crystals. As is well known, the liquid crystal has a thin and long molecular structure, optical anisotropy having an orientation in an array, and polarization in which the direction of molecular arrangement changes depending on its size when placed in an electric field.

That is, a general liquid crystal display device has a liquid crystal bonded through a liquid crystal layer between a first substrate having an array layer for driving a liquid crystal and a second substrate having a color filter layer for color implementation. The panel is an essential component, which causes a difference in transmittance by changing the arrangement direction of the liquid crystal molecules with an electric field inside.

The transmittance difference of the liquid crystal panel is displayed in the form of a color image by reflecting the color combination of the color filter through the light of the back light placed on the back.

A general LCD manufacturing process may be divided into a cell process of completing a liquid crystal panel and a module process of integrating a liquid crystal panel and a backlight with the liquid crystal panel.

The dual cell process repeats the process of thin film deposition, photo-lithography, etching, etc. several times to implement an array layer and a color filter layer on each substrate. After forming a seal pattern for bonding to any one of the second substrates, the two substrates are bonded to each other with the liquid crystal layer interposed therebetween to complete the liquid crystal panel. The completed liquid crystal panel is a polarizing plate and a driving circuit in a module process. After the furnace lamp is attached, it is integrated with the backlight to form a liquid crystal display device.

On the other hand, such a liquid crystal display device is to select a high-quality liquid crystal display device through a variety of inspection process, the present inspection equipment of the liquid crystal display device, if the minute dust (D) on the surface of the liquid crystal panel, the operator is practically It is difficult to accurately classify the fine dust D and the point defect of a specific pixel.

Therefore, the fine dust accumulated on the surface of the liquid crystal panel can be easily removed by washing, but it is difficult to accurately classify it, so that even if it is not a real defect, it is treated as a defect, which in turn lowers the reliability of the inspection process. This results in a problem of lowering the yield of the process and causing a loss of manufacturing cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object of the present invention is to provide an inspection system for a display device capable of accurately detecting only a defect of a liquid crystal panel.

Through this, the second object is to improve the reliability of the inspection process and the efficiency of the inspection process.

In order to achieve the above object, the present invention is the first step of proceeding the lighting test of the inspection object to obtain a driving image through the imaging unit, and whether the inspection object is defective first through the driving image In the second step of determining, and the inspection object that the defect is not generated by the first determination proceeds to a subsequent process, the inspection object irradiated with light is irradiated with light to illuminate the inspection object generated by the primary determination. A third step of acquiring, a fourth step of secondly determining whether or not the inspection object is defective through the illumination image, and the inspection object, in which foreign matter defect is not generated by the second determination, is discarded, and The inspection object in which the foreign object defect is generated by the difference determination includes a fifth step of collecting, comparing, and analyzing the driving image and the illumination image. Provides an inspection method for the inspection system.
In this case, the imaging unit detects a luminance difference of the lighting test, detects a first defective part in the driving image, and detects a second defective part in the illumination image, and in the fifth step, After collecting the moving image and the illumination image, the first and second defective areas overlapping each other are removed to extract only the first defective areas.
Then, the inspection object including the first defective portion is discarded, and when there is no first defective portion, the inspection object is transferred to a subsequent process after the cleaning process is performed.

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As described above, according to the present invention, by applying an electrical signal to a liquid crystal panel or a modular liquid crystal display device, the vision inspection for detecting defects through high resolution image acquisition is automated. And the inspection process can proceed precisely, there is an effect that can improve the reliability of the inspection process.

In addition, the method further includes a foreign material detection process, and precisely distinguishes the fine dust accumulated on the surface of the liquid crystal panel or the modular liquid crystal display device and the defects of specific pixels (PD; Point Defect). It is possible to prevent a problem that the liquid crystal panel or the modular liquid crystal display device is disposed of by fine dust, thereby increasing productivity and lowering manufacturing cost.

1 is a flowchart showing step by step a manufacturing process of a display device;
2 schematically illustrates a vision inspection system of a display device according to an exemplary embodiment of the present invention.
3 is a flowchart illustrating a detailed operation of a vision inspection system of a display device according to an exemplary embodiment of the present invention.
4a to 4e are photographs taken through the imaging unit during vision inspection of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 is a flow chart illustrating a manufacturing process of a display device step by step, the display device contrast ratio (large contrast ratio) is suitable for moving picture display and low power consumption, the liquid crystal that is utilized in various fields, such as notebooks, monitors, TV The display device will be described as an example. The liquid crystal display first performs a TFT-LCD cell process St10, and forms a liquid crystal cell through the cell process St10.

In more detail, the TFT-LCD cell process (St10) is largely divided into the color filter substrate and the array substrate formation (St11), the alignment layer formation (St12), the failure turn and spacer formation (St13), the liquid crystal dropping (St14), and the bonding ( St15), cutting (St16), and cell inspection step (St17).

Accordingly, the first step St11 of the TFT-LCD cell process St10 is a step of forming an array substrate and a color filter substrate, respectively.

At this time, a plurality of gate wirings and data wirings intersect each other on the inner surface of the array substrate, and thin film transistors (TFTs) are provided at each crossing point to correspond one-to-one with transparent pixel electrodes formed in each pixel. Connected.

The inner surface of the color filter substrate is a color filter of red (R), green (G), and blue (B) color as an example corresponding to each pixel, and each of them includes a gate wiring, a data wiring, and a thin film. A black matrix covering non-display elements such as transistors is provided, and a transparent common electrode covering them is provided.

The second step St12 is a step of forming an alignment layer on the array substrate and the color filter substrate, and includes coating and curing of the alignment layer and a rubbing treatment process.

The third step St13 forms a failure turn so that the liquid crystal to be interposed between the array substrate and the color filter substrate is prevented from leaking, and a spacer having a constant size is formed to maintain a precise and uniform gap between the array substrate and the color filter substrate. It is a process of spreading.

The fourth step (St14) of the TFT-LCD cell process (St10) is a step of dropping liquid crystal onto one of the selected substrates, and the fifth step (St15) is a bonding process of the array substrate and the color filter substrate. After that, the sixth step (St16) of cutting the bonded substrate in cell units is performed.

Lastly, the seventh step St17 is a cell inspection process of the liquid crystal panel, in which an auto probe inspection of an electric signal is applied.

In the auto probe inspection, a failure of the liquid crystal panel is detected by applying an electric signal by a probe contact to a pad exposed to the outside to substantially drive the liquid crystal panel.

Through the automatic probe inspection process, high-quality liquid crystal panels are selected.

As a result, the TFT-LCD cell process St10 is completed, thereby completing the liquid crystal panel.

Next, a polarizing plate attaching process (St20) for attaching a polarizing plate to each of the array substrate and the color filter substrate of the completed liquid crystal panel is performed. The polarizing plate serves to change light sources into linear light on both sides of the liquid crystal panel. do.

Next, the driving circuit attaching process St30 is performed, and the driving circuit attaches the driving circuit for connecting the electrical signal to the array substrate of the liquid crystal panel through OLB (out lead bonding) and tap soldering. .

Each of these driving circuits is divided into a gate driver circuit that scans and transmits an on / off signal of a thin film transistor through a gate wiring, and a data driver circuit that transfers image signals for each frame through a data wiring, and is located at two adjacent edges of the liquid crystal panel. Can be.

This completes the actual driveable liquid crystal panel.

Therefore, in the liquid crystal panel having the above-described structure, when the thin film transistor selected for each gate wiring is turned on by the on / off signal of the gate driving circuit which is scanned and transmitted, the signal voltage of the data driving circuit is transferred to the corresponding pixel electrode through the data wiring. The direction of the liquid crystal molecules is changed by the electric field between the pixel electrode and the common electrode, thereby indicating the transmittance difference.

Next is the backlight assembly and modularization process (St40). The backlight assembly process includes a light source, a light guide to guide the light source to the lower surface of the liquid crystal panel, a light guide plate to guide the light incident from the light source toward the liquid crystal panel, and a plurality of optical sheets. Locate it.

Alternatively, in the above description, the edge type method using the light guide plate has been described, but a direct type in which a plurality of light sources are arranged side by side under the liquid crystal panel with the light guide plate omitted may be used.

In this case, a fluorescent lamp such as a cold cathode fluorescent lamp or an external electrode fluorescent lamp may be used as the light source. Alternatively, a light emitting diode lamp may be used as a light source in addition to the fluorescent lamp.

After the backlight assembly process, the modularization process is performed.

The modularization process is a process of modularizing the liquid crystal panel and the backlight through the top cover, the support main and the cover bottom. The top cover has a rectangular frame shape in which a cross section is bent in a shape to cover the top and side edges of the liquid crystal panel. The front surface of the cover is opened to display an image implemented in the liquid crystal panel.

In addition, the cover bottom, which is the basis for assembling the entire apparatus of the liquid crystal display device due to the mounting of the liquid crystal panel and the backlight, is configured by vertically bending the four edges thereof in a rectangular plate shape.

In addition, the support main seated on the cover bottom and covering the edges of the liquid crystal panel and the backlight is assembled with the top cover and the cover bottom to complete the modular liquid crystal display.

Next, a final inspection process St50 of the modular liquid crystal display device is performed.

The inspection process inspects whether there is a defect in the modular liquid crystal display, and detects a final defect in the modular liquid crystal display according to the inspection result.

The modular liquid crystal display device more accurately detects the defect of the liquid crystal panel and the defect of the modular liquid crystal display device which are not detected in the seventh step St17 of the TFT-LCD cell process St10 through the inspection process St50. Will be checked.

Among the modular liquid crystal display devices which have undergone the inspection process St50, the modular liquid crystal display device, which has been determined to be defective, is determined by the operator to decide whether to dispose of them.

On the other hand, the auto-probe inspection of the seventh step (St17) of the TFT-LCD cell process (St10) and the inspection process (St50) for finally inspecting the modular liquid crystal display device are both liquid crystal panels or modular liquid crystal display devices. It includes vision inspection to detect defects by applying an electrical signal to the high-resolution image acquisition.

Vision inspection is a very important inspection process that detects point defects of specific pixels such as line defects and point defects such as short circuit and disconnection. The inspection process should proceed quickly to improve the efficiency of the process.

Here, the present invention can proceed the inspection process more quickly and precisely by automating vision inspection, it is possible to improve the reliability of the inspection process.

In addition, by accurately classifying the fine dust on the surface of the liquid crystal panel or the modular liquid crystal display and the specific pixel defects (PD; Point Defect), the liquid crystal panel or The problem that the modular liquid crystal display device is discarded can be prevented from occurring, thereby increasing productivity and lowering manufacturing cost.

2 is a diagram schematically illustrating a vision inspection system of a display device according to an exemplary embodiment of the present invention.

As shown in the drawing, the inspection apparatus includes an inspection table 100, an imaging unit 123, an illumination unit 125, and a control system 127.

In more detail, the inspection table 100 is a place where an inspection is performed, and a stage 121 on which an LCD panel or a modular liquid crystal display device 111 (hereinafter referred to as an inspection object) is placed on the inspection table 100. Located.

In this case, the stage 121 may be driven in various ways such as a horizontal method or a tilting method, and may rotate the stage 121 little by little even during the vision inspection.

Accordingly, the inspection object 111 can be inspected in various directions while the stage 121 on which the inspection object 111 is seated is rotated little by little, so that a defect in which a defect is differently determined according to a viewing angle can also be detected.

In addition, an imaging unit 123 is provided for capturing a defect of the inspection object 111 above the stage 121. The imaging unit 123 scans a plurality of wires of the inspection object 111 in high resolution. To camera.

The imaging unit 123 may be photographed while moving in the vertical direction while moving to the upper, lower, left and right regions from the upper portion of the inspection object 111 or scanning in the horizontal direction. At this time, the imaging unit 123 photographs the entire surface of the inspection object 111 or transmits an image obtained by photographing the entire region of the inspection object 111 while scanning in a predetermined direction to the control system 127.

The image pickup unit 123 enlarges the defective portion of the inspection object 111 to be photographed by a worker, and the image pickup unit 123 calculates the position of the defective portion in coordinates. The coordinates of the defective parts calculated in this way are transmitted to the control system 127 and stored.

Here, the defective area is an area where luminance unevenness of the inspection object 111 occurs, which is a line of specific defects such as line defects and point defects such as short circuits and disconnection of the inspection object 111. It may be caused by PD (Point Defect) or fine dust attached to the surface of the inspection object 111.

The imaging unit 123 detects a defect on the inspection object 111 at a very high speed compared to the inspection time by the human eye.

And, the lighting unit 125 is located on one side of the inspection object 111, the light emitted to the illumination unit 125 is irradiated from one side of the inspection object 111 to reach the other side.

The foreign matter attached to the surface of the inspection object 111 is inspected through the lighting unit 125.

That is, when a foreign material is attached to the surface of the inspection object 111, a shadow is generated near the area where the foreign material is attached by the light irradiated by the illumination unit 125, and photographed by the imaging unit 123 By transmitting the image thereof to the control system 127, the foreign matter attached to the surface of the inspection object 111 is inspected. We will discuss this in more detail later.

The control system 127 is responsible for the control for the lighting unit 125 and the defect inspection, the driving unit for selectively driving the imaging unit 123, the lighting unit 125 or adjust the overall drive, and the imaging unit 123 And an inspection unit for storing and reading the photographed information.

The inspection method of the vision inspection system for a display device of the present invention having the above components is as follows.

First, the illumination unit 125 is driven to irradiate light onto the surface of the inspection object 111, and then photographs the entire surface of the inspection object 111 through the imaging unit 123 to detect a luminance difference on the inspection object 111. The illumination image is transmitted to the inspection unit of the control system 127.

The control system 127 detects the position and the number information of the defective area on the surface of the inspection object 111 through the transmitted illumination image.

Subsequently, after driving the inspection object 111, the front surface of the inspection object 111 is photographed through the imaging unit 123, and then the control image 127 detects the driving image of the luminance difference on the inspection object 111. To the inspection department.

At this time, the control system 127 detects the position and the number information of the possible defects on the surface of the inspection object 111 and the interior of the inspection object 111 through the transmitted driving image.

Here, the order of acquiring the illumination image and the driving image is not particularly limited since any one of them is performed first and the others proceed sequentially.

Then, the inspection unit of the control system 127 collects the illumination and the driving image, and removes the defectable portions overlapping each other, that is, the region where the luminance difference occurs, among the defectable portions of the illumination and the driving image, thereby substantially failing the driving image. Only extract possible areas.

In this case, the defective part of the illumination image is an area where the luminance difference on the inspection object 111 is generated by a defect generated by foreign matter such as fine dust present on the surface of the inspection object 111, and the defective portion of the driving image. Defects caused by foreign matter such as fine dust present on the surface of the inspection object 111 and specific defects such as line defects and point defects such as short circuits and disconnection inside the inspection object 111 This is an area where a luminance difference on the inspection object 111 occurs due to a defective point (PD) of the pixel.

Therefore, the defective parts that overlap each other in the illumination and the driving image are areas in which the luminance difference is caused by foreign matter such as fine dust existing on the surface of the inspection object 111, which can be removed through a simple cleaning process. The inspection object 111 in which such a defect has occurred may be proceeded to a subsequent process.

In addition, defects that do not overlap each other in the illumination and driving images are defects that are substantially generated inside the inspection object 111 and cannot be removed by a simple cleaning process. The inspection object 111 in which such defects are generated is The next process is determined by determining whether to dispose of the waste at the discretion of the worker.

That is, the vision inspection process of the present invention accurately distinguishes the fine dust that has accumulated on the surface of the inspection object 111 and the defect of a specific pixel (PD; Point Defect), and thus, the fine dust that can be easily removed through a cleaning process. This prevents the problem of discarding the liquid crystal panel or the modular liquid crystal display device, thereby increasing productivity and lowering manufacturing costs.

3 is a flowchart illustrating a detailed operation of a vision inspection system of a display device according to an exemplary embodiment of the present invention.

4A through 4E are photographs taken through the imaging unit during vision inspection of the present invention.

As shown in FIG. 3, the inspection object (111 of FIG. 2), that is, vision inspection of the display device according to the embodiment of the present invention, first prepares the inspection object (111 of FIG. 2) (st100), and displays it. It is placed in the vision inspection system for the device and set up for inspection.

Next, as illustrated in FIG. 4A, a signal is applied to the inspection object (111 of FIG. 2) to simulate driving the inspection object (111 of FIG. 2), and then the inspection object (123 of FIG. Photograph the entire surface of 111 of FIG. 2 to detect the luminance difference on the inspection object (111 of FIG. 2) (st110), and determine whether the inspection object (111 of FIG. 2) is defective according to the detected luminance difference. st120).

That is, after photographing the entire surface of the inspection object (111 of FIG. 2) through the imaging unit (123 of FIG. 2) in this step, the luminance difference on the inspection object (111 of FIG. 2) is detected as shown in FIG. The driving image is obtained. The driving image is transferred to the inspection unit of the control system 127 of FIG. 2, and the inspection unit determines whether the inspection object (111 of FIG. 2) is defective.

Here, the inspection unit compares the driving image with a reference luminance value to determine the position and the number information of the first defective portion possible due to the luminance difference on the inspection object (111 in FIG. 2).

Here, the reference luminance value is preferably set to a value obtained by collecting the luminance values within a certain measurement range among the luminance values measured for the plurality of inspection objects (111 in FIG. 2).

That is, if the luminance difference does not occur on the inspection object (111 in FIG. 2), the inspection object (111 in FIG. 2) proceeds to the subsequent process (st190) immediately after receiving a good decision, and the image on the inspection object (111 in FIG. 2). When the first defective area where the luminance difference is generated is detected, the inspection object (111 in FIG. 2) performs the foreign material detection test st130.

The foreign material detection test st130 does not drive the inspection object (111 of FIG. 2), and the inspection object (FIG. 2 of FIG. 2) through the illumination unit 125 of FIG. 2. After irradiating light to the surface of 111, the front surface of the inspection object (111 of FIG. 2) is photographed through the imaging unit 123 of FIG. 2 to detect a luminance difference on the inspection object (111 of FIG. 2).

Here, when light is irradiated to the surface of the inspection object (111 of FIG. 2) from one side of the inspection object (111 of FIG. 2) through the lighting unit (125 of FIG. 2), the surface of the inspection object (111 of FIG. 2) When foreign matter such as fine dust is attached, shadows are generated in the opposite direction to which light is irradiated, and reflected light is generated in the direction in which light is irradiated.

At this time, the brightness difference caused by the shadow and the reflected light is photographed through the imaging unit 123 of FIG. 2 to obtain an illumination image including the second defective part as illustrated in FIG. 4C.

The illumination image thus obtained is transmitted to the inspection unit of the control system 127 of FIG. 2, and determines whether the inspection object (111 of FIG. 2) is defective according to the detected luminance difference (st140).

Here, the inspection unit compares the illumination image with the reference luminance value to determine the position and the number information of the second defective possibility portion by the luminance difference on the inspection object (111 in FIG. 2) as shown in FIG. 4D.

In this case, when no luminance difference occurs in the illumination image, no foreign matter exists on the surface of the inspection object (111 in FIG. 2), and thus, the inspection object (111 in FIG. 2) is determined to have only a defect detected during the lighting inspection. It is determined (st180) whether to dispose of the waste at the discretion of the operator.

On the contrary, when a luminance difference occurs in the illumination image, the inspection unit collects the driving image acquired during the lighting inspection and the illumination image obtained during the foreign material detection inspection, and compares the first defective portion and the second defective portion in comparison (st150). Done.
By doing this, by removing the defective parts overlapping each other among the first defective part and the second defective part, and extracting only the first defective part of the driving image obtained during the foreign material detection test as shown in FIG. The inspection object (111 in FIG. 2) is third-determined (st160).
That is, after comparing the first defective part and the second defective part according to the collection of the driving image and the illumination image, and removing the first defective part and the second defective part that overlap each other in the driving image and the illumination image. , Check whether there are remaining defective parts on the inspection object (111 in FIG. 2).

At this time, when no defect possible part is present on the inspection object (111 of FIG. 2), the inspection object (111 of FIG. 2) is all the first defect possible parts detected during the lighting test (111 of FIG. 2). It can be seen that the foreign matter such as fine dust attached to the surface of the).

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Through this, the inspection object (111 of FIG. 2) through the cleaning process (st170), after removing the foreign matter adhering to the surface of the inspection object (111 of Figure 2), and proceeds directly to the subsequent process (st190).

In addition, even when the first and second defective areas are overlapped with each other and the defective areas are present on the inspection object (111 of FIG. 2), the defects of the inspection object (111 of FIG. 2) are determined by the inspection object (FIG. 2) of the specific pixels that cannot be removed by a simple cleaning process (st170), that is, such as line defects and point defects such as short circuits and breaks in wirings (PD). With Point Defect, it is determined (st180) whether or not to discard at the worker's discretion.

As described above, the vision inspection system for a display device of the present invention applies a electrical signal to a liquid crystal panel or a modular liquid crystal display device to automate a vision inspection that detects defects through high resolution image acquisition, so that The inspection process can be carried out precisely, and the reliability of the inspection process can be improved.

In addition, the method further includes a foreign material detection process, and precisely distinguishes the fine dust accumulated on the surface of the liquid crystal panel or the modular liquid crystal display device and the defects of specific pixels (PD; Point Defect). The problem that the liquid crystal panel or the modular liquid crystal display device is disposed of by the fine dust can be prevented from occurring, thereby increasing productivity and lowering manufacturing cost.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

100: inspection unit, 111: inspection object
121: stage, 123: imaging unit, 125: lighting unit, 127: control system

Claims (10)

delete delete delete A first step of conducting a lighting test of the inspection object to acquire a driving image through the imaging unit;
A second step of primarily determining whether the inspection object is defective through the driving image;
A third step of performing a subsequent process on the inspection object in which the defect is not generated by the primary determination, and obtaining an illumination image by irradiating light to the inspection object in which the defect is generated by the primary determination;
A fourth step of determining whether the inspection object is defective through the illumination image;
The inspection object which is not caused by foreign matters by the second determination is discarded, and the inspection object that is caused by foreign matters by the second determination collects, compares and analyzes the driving image and the illumination image. 5th step
Inspection method of the vision inspection system for a display device comprising a.
The method of claim 4, wherein
And the imaging unit detects a luminance difference of the lighting inspection, detects a first defective portion in the driving image, and detects a second defective portion in the illumination image.
The method of claim 5,
In the fifth step, after the driving image and the illumination image is collected, the first and second defective areas overlapping each other between the first and second defective areas are removed.
And an inspection method of the vision inspection system for a display device, extracting only the first defective portion that does not overlap with the second defective portion.
The method of claim 6,
And a method for inspecting a vision inspection system for a display device, wherein the inspection object including the first defective portion is disposed.
The method of claim 6,
In the absence of the first defective portion, the inspection object is delivered to the subsequent process after the cleaning process, the inspection method of the vision inspection system for a display device.
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