This application claims priority to Korean Patent Application No. 10-2022-0104322, filed on Aug. 19, 2022, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which in its entirety is herein incorporated by reference.
The disclosure relates to an inspection device with improved reliability of defect determination and a method of inspecting a display device using the inspection device.
Various inspection devices are used to inspect a display device. Among the inspection devices, an optical inspection device inspects the display device using a camera. The optical inspection device inspects the display device for a short-circuit defect, an open-circuit defect, or a presence of fine particles in units of several micrometers to several tens of micrometers, for example. In addition, the optical inspection device inspects the display device for foreign substances or residual films of about several hundred micrometers or more.
The disclosure provides an inspection device with improved reliability of defect determination.
The disclosure provides a method of inspecting a display device using the inspection device.
An embodiment of the inventive concept provides an inspection device including an imaging unit which captures an inspection target and outputs image data corresponding to the inspection target, a data extraction unit which receives the image data and extracts inspection data corresponding to an inspection area of the inspection target from the image data, a setting unit which sets a threshold value based on a grayscale value of comparative data compared with the inspection data, and an inspection unit which determines whether the inspection target is defective based on the threshold value.
In an embodiment, the setting unit sets the threshold value to increase as the grayscale value of the comparative data increases.
In an embodiment, the grayscale value of the comparative data has a range including a first section, a second section, and a third section.
In an embodiment, the setting unit sets the grayscale value of the comparative data and the threshold value such that an increase amount of the grayscale value of the comparative data is directly proportional to an increase amount of the threshold value in each of the first section, the second section, and the third section.
In an embodiment, a relationship between the increase amount of the grayscale value of the comparative data and the increase amount of the threshold value in the first section is defined as a first proportional value, a relationship between the increase amount of the grayscale value of the comparative data and the increase amount of the threshold value in the second section is defined as a second proportional value, a relationship between the increase amount of the grayscale value of the comparative data and the increase amount of the threshold value in the third section is defined as a third proportional value, the third proportional value is set greater than the second proportional value by the setting unit, and the second proportional value is set greater than the first proportional value by the setting unit.
In an embodiment, the setting unit sets the threshold value to which a first correction value is applied in the first section, sets the threshold value to which a second correction value is applied in the second section, and sets the threshold value to which a third correction value is applied in the third section.
In an embodiment, a reference grayscale value is defined in a range of the grayscale value of the comparative data, and the inspection unit does not determine whether the inspection target is defective in a section where the grayscale value is greater than the reference grayscale value.
In an embodiment, the inspection area includes a first inspection area and a second inspection area, the data extraction unit extracts first inspection data corresponding to the first inspection area and second inspection data corresponding to the second inspection area, and the inspection unit determines whether the first and second inspection data are defective based on different threshold values from each other.
In an embodiment, the comparative data correspond to a comparative area from the image data to be compared with the inspection area.
In an embodiment, the inspection target includes a plurality of cells.
In an embodiment, the inspection target includes a plurality of layers, and the inspection area and the comparative area are defined in a same layer.
In an embodiment, the inspection device further includes a light source which irradiates a light and an optical member which controls a path of the light to direct toward the inspection target.
An embodiment of the inventive concept provides a method of inspecting an inspection target. The inspection method includes capturing, by an imaging unit, the inspection target and to output image data, receiving, by a data extraction unit, the image data and to extract inspection data from the image data, setting, by a setting unit, a threshold value based on a grayscale value of comparative data, and comparing the inspection data with the comparative data to determine whether the inspection target is defective based on the threshold value.
In an embodiment, the extracting the inspection data and the comparative data includes setting an inspection area and a comparative area.
In an embodiment, an increase amount of the grayscale value of the comparative data and an increase amount of the threshold value have a linear relationship.
In an embodiment, the grayscale value of the comparative data has a range including a first section, a second section, and a third section, the grayscale value of the comparative data and the threshold value have a first linear relationship in the first section, the grayscale value of the comparative data and the threshold value have a second linear relationship in the second section, and the grayscale value of the comparative data and the threshold value have a third linear relationship in the third section.
In an embodiment, the third linear relationship has a slope greater than a slope of the second linear relationship, and the second linear relationship has the slope greater than a slope of the first linear relationship.
In an embodiment, the method further includes providing the inspection target and irradiating a light to the inspection target using a light source.
In an embodiment, the irradiating the light to the inspection target includes controlling a path of the light toward the inspection target using an optical member.
In an embodiment, the inspection target has a multi-layer structure including a metal layer, and the outputting the image data by the imaging unit includes capturing the metal layer and outputting the image data.
According to the above, the inspection device determines whether the display panel is defective by comparing the image taken from the inspection area with the image taken from the comparative area. The threshold value is set to differ depending on the grayscale value of the comparative area in order to determine whether the inspection area is defective. In detail, the threshold value is set to have a lower value in a section where the grayscale value of the comparative area is relatively low to further detect whether the inspection area is defective, and the threshold value is set to have a higher value in a section where the grayscale value of the comparative area is relatively high to prevent errors in detecting defects. Accordingly, the reliability of defect detection of the inspection device is improved, and a yield of products inspected by the inspection device increases.
The above and other advantages of the disclosure will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which:
The disclosure may be variously modified and realized in many different forms, and thus illustrative embodiments will be exemplified in the drawings and descri bed in detail hereinbelow. However, the disclosure should not be limited to the specific disclosed forms, and be construed to include all modifications, equivalents, or replacements included in the spirit and scope of the disclosure.
In the disclosure, it will be understood that when an element (or area, layer, or portion) is referred to as being “on”, “connected to” or “coupled to” another element or layer, it may be directly on, connected or coupled to the other element or layer or intervening elements or layers may be present.
Like numerals refer to like elements throughout. In the drawings, the thickness, ratio, and dimension of components are exaggerated for effective description of the technical content.
As used herein, the term “and/or” may include any and all combinations of one or more of the associated listed items.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, a first element discussed below could be termed a second element without departing from the teachings of the disclosure. As used herein, the singular forms, “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another elements or features as shown in the drawing figures.
“About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). The term “about” can mean within one or more standard deviations, or within +30%, 20%, 10%, 5% of the stated value, for example.
The term “unit” as used herein is intended to mean a software component or a hardware component that performs a predetermined function. The hardware component may include a field-programmable gate array (“FPGA”) or an application-specific integrated circuit (“ASIC”), for example. The software component may refer to an executable code and/or data used by the executable code in an addressable storage medium. Thus, the software components may be object-oriented software components, class components, and task components, and may include processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, micro codes, circuits, data, a database, data structures, tables, arrays, or variables, for example.
Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It will be further understood that the terms “include” and/or “including”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Hereinafter, embodiments of the disclosure will be described with reference to accompanying drawings.
Referring to
A light source LA may provide a light Lt to the inspection target 500. The light Lt may be irradiated to an optical member OM. The light Lt provided to the optical member OM may travel to an inspection target 500 after passing through the optical member OM. In detail, the optical member OM may be placed at a position to allow a path of the light Lt to direct to the inspection target 500. The light Lt may have a visible light wavelength, however, it should not be limited thereto or thereby. In an embodiment, the light Lt may have an ultraviolet light wavelength.
The inspection target 500 may be disposed on a stage ST. Referring to
The inspection target 500 may include a first area 500-D and a second area 500-ND. The first area 500-D may correspond to a display area of the display device DD (refer to
The cells Sn (or pixels) may be arranged in the first area 500-D, and each of the cells Sn (or pixels) may include sub-pixels. The sub-pixels may include a red sub-pixel, a blue sub-pixel, and a green sub-pixel, for example, however, this is merely an illustrative embodiment. In an embodiment, the color of sub-pixels constituting one pixel may be changed in various ways.
The inspection target 500 may include an inspection area SPA and a comparative area CPA. The inspection area SPA may be an area that is inspected to determine whether the inspection target 500 is defective. Although not shown in drawing figures, the inspection area SPA may be provided in plural in the first area 500-D. In this case, the plural inspection areas SPA may be inspected at the same time in a defect detection process described later.
The comparative area CPA may be an area similar to the inspection area SPA and may be defined adjacent to the inspection area SPA. The comparative area CPA may be defined as an area from which comparative data CPD used to compare the inspection area SPA with the comparative area CPA are extracted to determine whether the inspection target 500 is defective. A process of selecting the comparative area CPA may include selecting several candidate areas from the inspection area SPA and selecting the area most similar to the inspection area SPA, however, the disclosure should not be limited thereto or thereby. In an embodiment, the comparative data CPD may be selected based on data stored in the inspection device 1000.
Referring to
The display device DD may include a plurality of layers. In detail, the display device DD may include a display panel DP, an input sensing layer ISL, and a window WM. The display panel DP may include a base layer BS, a circuit layer DP-CL, a display element layer DP-ED, and an encapsulation layer TFE.
The inspection target 500 may include some of components of the display device DD. In an embodiment, the inspection target 500 may be the display device DD, or the inspection target 500 may include only the display panel DP. In an embodiment, the inspection target 500 may be a preliminary display panel before being formed into the display panel DP. The preliminary display panel may be in a state in which the circuit layer DP-CL is completely formed or only a portion of the circuit layer DP-CL is formed.
In an embodiment of the disclosure, in a process of obtaining image data IMD from the inspection target 500, the image data IMD may be data generated by imaging the same layer of the inspection target 500. When the inspection area SPA and the comparative area CPA are in different layers, a grayscale value of the comparative area CPA may differ greatly compared with a case when the inspection area SPA and the comparative area CPA are in the same layer. As it is difficult to conduct accurately the inspection by difference of the grayscale value, the inspection area SPA and the comparative area CPA may be in the same layer.
In an embodiment, the imaging unit 100 may be placed on a path of a light RLt reflected by the inspection target 500. The imaging unit 100 may capture the inspection target 500 and may output the image data IMD corresponding to the inspection target 500. In detail, the imaging unit 100 may generate the image data IMD from the light RLt reflected by the inspection target 500 and may output the image data IMD to the data extraction unit 200. The image data IMD may be white light or fluorescent light captured images.
In an embodiment, the data extraction unit 200 may receive the image data IMD and may extract inspection data SPD and comparative data CPD from the image data IMD. Referring to
The data extraction unit 200 may provide the comparative data CPD to the setting unit 300 and may provide the inspection data SPD and the comparative data CPD to the inspection unit 400. The data extraction unit 200 may be an arithmetic processing unit. In an embodiment, the data extraction unit 200 may be a graphics processing unit.
The setting unit 300 may receive the comparative data CPD and may set a threshold value Th based on the grayscale value of the comparative data CPD. The set threshold value Th may be provided to the inspection unit 400. The threshold value Th may be a reference value according to a difference in grayscale value between the inspection data SPD and the comparative data CPD and may be used as a reference value to determine whether the inspection target 500 is defective. In an embodiment, the setting unit 300 may set the threshold value Th to allow the threshold value Th to increase as the grayscale value of the comparative data CPD increases, however, it should not be limited thereto or thereby. The setting of the threshold value Th by the setting unit 300 will be described in detail later.
The inspection unit 400 may receive the inspection data SPD and the comparative data CPD from the data extraction unit 200 and may receive the threshold value Th from the setting unit 300. The inspection unit 400 may compare the inspection data SPD with the comparative data CPD and may determine whether the inspection target 500 is defective based on the threshold value Th. In detail, when a value corresponding to the difference between the grayscale value of the inspection data SPD and the grayscale value of the comparative data CPD is greater than the threshold value Th, the inspection unit 400 may determine that the inspection target 500 is defective, and when the value corresponding to the difference between the grayscale value of the inspection data SPD and the grayscale value of the comparative data CPD is equal to or smaller than the threshold value Th, the inspection unit 400 may determine that the inspection target 500 is normal. These processes are performed sequentially, so that all parts of the inspection target 500 may be inspected for defects. However, the disclosure should not be limited thereto or thereby. In an embodiment, the inspection data SPD may be obtained from a plurality of inspection areas SPA of the inspection target 500. The inspection unit 400 may set the inspection data SPD to be inspected from the inspection data SPD and may compare the inspection data SPD with the comparative data CPD based on the threshold value Th to determine whether the inspection target 500 is defective.
Referring to
In an embodiment, the data extraction unit 200 may generate first inspection data SPD-1 corresponding to the first inspection area SPA-1 and second inspection data SPD-2 corresponding to the second inspection area SPA-2 and may provide the first inspection data SPD-1 and the second inspection data SPD-2 to the inspection unit 400. The inspection unit 400 may determine whether the first and second inspection areas SPA-1 and SPA-2 are defective based on the threshold value Th set from the first inspection data SPD-1 and the second inspection data SPD-2.
In detail, the setting unit 300 may provide the threshold value Th set from the second inspection data SPD-2 to the inspection unit 400, and the inspection unit 400 may determine whether the first inspection area SPA-1 is defective based on the threshold value Th set from the second inspection data SPD-2. The setting unit 300 may provide the threshold value Th set from the first inspection data SPD-1 to the inspection unit 400, and the inspection unit 400 may determine whether the second inspection area SPA-2 is defective based on the threshold value Th set from the first inspection data SPD-1. However, the disclosure should not be limited thereto or thereby. In an embodiment, the setting unit 300 may provide the threshold value Th set from the second inspection data SPD-2 to the inspection unit 400 to determine whether the first inspection area SPA-1 is defective, however, the inspection unit 400 may determine whether the second inspection area SPA-2 is defective based on a predetermined threshold value Th.
In
Referring to
In an embodiment, the first section S1 may be wider than the second section S2, and the second section S2 may be wider than the third section S3, however, the disclosure should not be limited thereto or thereby. Each of first section S1, the second section S2, and the third section S3 may be changed in various ways.
In an embodiment, the setting unit 300 may set an increase amount of the comparative grayscale value CG to be directly proportional to an increase amount of the threshold value Th in each of the first section S1, the second section S2, and the third section S3. In detail, a relationship between a first grayscale value increase amount CG-G1 of the comparative data CPD and a first threshold value increase amount Th-G1 in the first section S1 may be defined as a first proportional value PV1, a relationship between a second grayscale value increase amount CG-G2 of the comparative data CPD and a second threshold value increase amount Th-G2 in the second section S2 may be defined as a second proportional value PV2, and a relationship between a third grayscale value increase amount CG-G3 of the comparative data CPD and a third threshold value increase amount Th-G3 in the third section S3 may be also referred to as a third proportional value PV3.
The third proportional value PV3 may be set greater than the second proportional value PV2 by the setting unit 300, and the second proportional value PV2 may be set greater than the first proportional value PV1 by the setting unit 300, however, the disclosure should not be limited thereto or thereby. In an embodiment, the third proportional value PV3 may be set equal to the second proportional value PV2, and the second proportional value PV2 may be set equal to the first proportional value PV1.
In an embodiment, the setting unit 300 may set the comparative grayscale value CG and the threshold value Th such that the increase amount of the comparative grayscale value CG and the increase amount of the threshold value Th have a linear relationship in each of the first section S1, the second section S2, and the third section S3. In detail, the comparative grayscale value CG and the threshold value Th may have a first linear relationship in the first section S1, may have a second linear relationship in the second section S2, and may have a third linear relationship in the third section S3.
In
A slope of the first linear relationship may correspond to the first proportional value PV1, a slope of the second linear relationship may correspond to the second proportional value PV2, and a slope of the third linear relationship may correspond to the third proportional value PV3. Accordingly, the slope of the third linear relationship may be greater than the slope of the second linear relationship, and the slope of the second linear relationship may be greater than the slope of the first linear relationship. That is, the slope of the third linear graph G3 may be greater than the slope of the second linear graph G2, and the slope of the second linear graph G2 may be greater than the slope of the first linear graph G1. However, the disclosure should not be limited thereto or thereby. In an embodiment, the slope of the third linear graph G3 may be the same as the slope of the second linear graph G2, and the slope of the second linear graph G2 may be the same as the slope of the first linear graph G1.
The threshold value Th shown by the y-axis may correspond to the reference value according to the grayscale value of the comparative data CPD and may be used as a reference to determine whether the inspection target 500 is defective. The threshold value Th may be selected from a range from 0 to 255.
According to a comparative example, the threshold value Th used to determine whether the inspection target 500 is defective may be fixed to a predetermined value, e.g., 23. Accordingly, even though positions of inspection areas are different in the inspection target 500 or the grayscale values of the comparative data CPD from inspection areas are different, the defects of the inspection areas are determined based on the same threshold value Th. In this case, an intrinsic defect may not be detected, or an extrinsic defect may be detected as the intrinsic defect, and thus, a reliability of the inspection may be deteriorated.
According to the disclosure, the threshold value Th may be changed depending on positions of the inspection areas in the inspection target 500 or the grayscale value of the comparative data CPD. In an embodiment, the intrinsic defect that may be missed in the comparative example may be detected by setting the threshold value Th at a relatively low level in the section where the comparative grayscale value CG of the comparative area CPA is relatively low, and the extrinsic defect that may be mis-determined as the intrinsic defect in the comparative example may not be mis-determined as the intrinsic defect by setting the threshold value Th at a relatively high level in the section where the comparative grayscale value CG of the comparative area CPA is high. The threshold voltage Th may be set as three linear graphs according to the comparative grayscale value CG of the comparative area CPA. As a result, the reliability of the defect determination by the inspection device may be improved, and a yield of products inspected by the inspection device may be improved. In addition, in a case where the region of interest for inspection is inspected, the threshold value Th may increase or decrease according to characteristics of the region of interest for inspection.
Referring to
In an embodiment, the inspection unit 400 may not determine whether the inspection target 500 is defective in a section where the comparative grayscale value CG is greater than the reference grayscale value CG-R. In detail, the setting unit 300 may set the threshold value Th in response to the comparative grayscale value CG of the comparative area CPA, however, the threshold value Th may not be set in the section where the comparative grayscale value CG is greater than the reference grayscale value CG-R of the third section S3 in which the reference grayscale value CG-R is set. Then, since the threshold value Th is not set in the section where the comparative grayscale value CG is greater than the reference grayscale value CG-R, the inspection unit 400 that does not receive the threshold value Th may not determine whether the inspection target 500 is defective, however, the disclosure should not be limited thereto or thereby. In an embodiment, the threshold value Th may be set to infinity (∞) or 255 in the section where the comparative grayscale value CG is greater than the reference grayscale value CG-R. Then, since the threshold value Th is infinity (∞), a value corresponding to the difference between the grayscale value of the inspection data SPD and the comparative grayscale value CG of the comparative data CPD is smaller than the threshold value Th, and thus, the inspection unit 400 may determine that the inspection target 500 is normal.
In an embodiment, the setting unit 300 may set the comparative grayscale value CG such that the increase amount of the comparative grayscale value CG of the comparative data CPD and the increase amount of the threshold value Th may have the linear relationship in each of the first section S1, the second section S2, and the third section S3. In detail, the increase amount of the comparative grayscale value CG and the increase amount of the threshold value Th may have the first linear relationship in the first section S1, may have the second linear relationship in the second section S2, and may have the third linear relationship in the third section S3.
In an embodiment, the linear relationship may be represented by a linear graph. The comparative grayscale value CG and the threshold value Th may have a first linear graph G1 in the first section S1, a second linear graph G2 in the second section S2, and a third linear graph G3a in the third section S3 corresponding to, respectively, the first linear relationship, the second linear relationship, and the third linear relationship. When compared with the graph of
As the reference grayscale value CG-R is set and whether the inspection target 500 is defective is not determined in the section where the comparative grayscale value CG is greater than the reference grayscale value CG-R, it is possible to prevent errors of determining non-defective products as defective in the section where the comparative grayscale value CG of the comparative area CPA is high. As a result, the reliability in determining the defects of the inspection device may be improved, and the yield of the products inspected by the inspection device may be improved.
Referring to
Referring to
In
A comparative grayscale value CGa may be 64, and the inspection grayscale value SGa may be within a range from 64 to 80. A maximum difference between the inspection grayscale value SGa and the comparative grayscale value CGa may be 16. According to a comparative example, since the threshold value is fixed to 23, the difference between the inspection grayscale value SGa and the comparative grayscale value CGa may not be greater than the threshold value. Accordingly, the error that the intrinsic defect is not determined as the defect may occur. However, according to the disclosure, the threshold value Th may be lowered to about 12 by taking into account the comparative grayscale value CGa. Accordingly, the difference between the inspection grayscale value SGa and the comparative grayscale value CGa may be greater than the threshold value Th, and thus, the intrinsic defect may be detected as the intrinsic defect. As a result, the reliability in determining the defects of the inspection device may be improved, and the yield of the products inspected by the inspection device may be improved.
Referring to
A comparative grayscale value CGb may be 256, and the inspection grayscale value SGb may be within a range from 224 to 256. A maximum difference between the inspection grayscale value SGb and the comparative grayscale value CGb may be 32. According to the comparative example, since the threshold value is fixed to 23, the difference between the inspection grayscale value SGb and the comparative grayscale value CGb may be greater than the threshold value. Accordingly, the error that the extrinsic defect of the normal products is determined as the defect may occur. However, according to the disclosure, the threshold value Th may be equal to or greater than about 200 by taking into account the comparative grayscale value CGb. Accordingly, the difference between the inspection grayscale value SGb and the comparative grayscale value CGb is smaller than the threshold value Th, and thus, the extrinsic defect may be prevented from being detected as the defect. As a result, the reliability in determining the defects of the inspection device may be improved, and the yield of the products inspected by the inspection device may be improved.
Referring to
Referring to
In an embodiment, the display panel DP may include the metal layer. In an embodiment, the input sensing layer ISL may also include the metal layer. Accordingly, the outputting of the image data IMD by the imaging unit 100 (S200) may be performed by capturing the metal layer included in the display panel DP or the input sensing layer ISL and outputting the image data IMD.
The data extraction unit 200 may receive the image data IMD and may extract the inspection data SPD and the comparative data CPD from the image data IMD (S300), however, the disclosure should not be limited thereto or thereby. In an embodiment, the data extraction unit 200 may extract only the inspection data SPD from the image data IMD and the inspection device 1000 (refer to
Referring to
The setting unit 300 may set the threshold value Th based on the grayscale value of the comparative data CPD (S400). In an embodiment, the setting unit 300 may set the threshold value Th to allow the threshold value Th to increase as the grayscale value of the comparative data CPD increases. Referring to
The inspection unit 400 may compare the inspection data SPD with the comparative data CPD and may determine whether the inspection target 500 is defective based on the threshold value Th (S500). In detail, the inspection unit 400 may compare the inspection data SPD with the comparative data CPD, which are provided from the data extraction unit 200, based on the threshold value Th provided from the setting unit 300 to determine whether the inspection target 500 is defective. Although not shown in drawing figures, the inspection unit 400 may determine that the inspection target 500 is defective when the value corresponding to the difference between the grayscale value of the inspection data SPD and the grayscale value of the comparative data CPD is greater than the threshold value Th and may determine that the inspection target 500 is normal when the value corresponding to the difference between the grayscale value of the inspection data SPD and the grayscale value of the comparative data CPD is equal to or smaller than the threshold value Th.
Although the embodiments of the disclosure have been described, it is understood that the disclosure should not be limited to these embodiments but various changes and modifications may be made by one ordinary skilled in the art within the spirit and scope of the disclosure as hereinafter claimed.
Therefore, the disclosed subject matter should not be limited to any single embodiment described herein, and the scope of the inventive concept shall be determined according to the attached claims.
Number | Date | Country | Kind |
---|---|---|---|
10-2022-0104322 | Aug 2022 | KR | national |