JP2008107100A - Inspection device and method of liquid crystal panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection device of a liquid crystal panel capable of preventing an inspection omission. <P>SOLUTION: In the liquid crystal panel 11, color filters in three colors of R, G and B for filtering light radiated from a backlight are installed. The inspection device 30 for inspecting the liquid crystal panel 11 includes a camera 31 for imaging the liquid crystal panel 11, and outputting its light reception signal; a backlight 32 for inspection for irradiating the liquid crystal panel 11 with light from the opposite side to the camera 31; a color filter 35 for correction interposed between the liquid crystal panel 11 and the camera 31, for filtering so that each light can be detected as light having the same intensity by the camera 31 when each light in each color transmitted through each color filter of the liquid crystal panel 11 has the same light quantity; and an operation processing part 33 for comparing a detection value acquired based on the light receiving signal outputted from the camera 31 with a prescribed inspection reference value, and detecting as a defect when exceeding the inspection reference value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal panel inspection apparatus and a liquid crystal panel inspection method.

  In the liquid crystal panel which is a main part of the liquid crystal display device, various inspections are performed to determine whether or not the product is defective in the manufacturing process, and these inspections include a so-called lighting inspection.

  In the lighting inspection, the entire liquid crystal panel is made into a black screen, and while irradiating the backlight for inspection from the back side in that state, the light leaking despite the black screen is detected by imaging from the front side, When the brightness of the light is not less than a predetermined inspection reference value, it is detected as a defect. This transmitted light is filtered into any color by R, G, B color filters formed in the liquid crystal panel.

  By the way, as a camera used for an inspection apparatus, a monochrome camera is usually used because of the number of pixels and cost. This monochrome camera has a sensitivity characteristic. For example, even when R, G, and B light have the same light quantity, they tend to detect light with high intensity in the order of B, G, and R. On the other hand, human vision also has sensitivity characteristics, and even with the same amount of R, G, B light, it tends to feel brighter in the order of G, R, B, which is different from the sensitivity characteristics of a monochrome camera. is doing.

  Therefore, it is considered to install a correction color filter between the camera and the liquid crystal panel in order to match the sensitivity characteristic of the camera to the human visual characteristic. As shown in FIG. 6, this correction color filter has a large amount of transmitted light in the order of B, R, and G, and when the light feels the same brightness when viewed by humans, The transmitted light is set to be filtered so that they can be detected as light of the same intensity in the camera. Thereby, the intensity of light detected by the camera can be corrected so as to match the human visual characteristics, and an appropriate inspection can be performed.

In addition, what was described in the following patent document 1 is known as an example of the above lighting inspection apparatuses.
JP 2003-194669 A

  By the way, as a cause of a defect that always transmits light, there are a failure of a TFT, a foreign matter mixed in a liquid crystal, and the like, but a foreign matter sandwiched between a polarizing plate and a glass substrate can also be a cause. Since such a foreign substance exists in the position away from the color filter by the thickness of the glass substrate, the light that is visually recognized due to the foreign substance passes through the color filters of different colors depending on the viewing angle. That is, parallax occurs in the defect based on the foreign matter interposed between the polarizing plate and the glass substrate, and the color of the visible light changes according to the viewing angle.

  For example, the B light having the light amount shown by the broken line in FIG. 6 is corrected to a light amount that is lower than the inspection reference value in the process of passing through the correction color filter, and is not detected as a defect. R or G light can exceed the reference value. Therefore, in such a case, there has been a problem that inspection failure occurs.

  The present invention has been completed based on the above-described circumstances, and an object thereof is to prevent inspection omissions.

  An inspection apparatus for a liquid crystal panel according to the present invention is an inspection apparatus used for inspecting a liquid crystal panel, imaging means for imaging the liquid crystal panel and outputting a light reception signal thereof, and the imaging for the liquid crystal panel. An inspection illumination device that emits light from the side opposite to the means side, a correction color filter for correcting the sensitivity characteristic with respect to the wavelength of the visible light region in the imaging means to be flat, and the imaging means The detection value obtained based on the received light signal is compared with a predetermined inspection reference value, and defect detection means for detecting as a defect when the inspection reference value is exceeded is provided.

  Further, the liquid crystal panel inspection method of the present invention is a liquid crystal panel inspection method, wherein the liquid crystal panel is irradiated with light by an inspection illumination device, and the liquid crystal panel is imaged by an imaging means from the opposite side. In this case, the correction color filter is used to filter the light so that the sensitivity characteristic with respect to the wavelength in the visible light region in the imaging unit becomes flat, and the detection obtained based on the received light signal output from the imaging unit by the defect detection unit. The value is compared with a predetermined inspection reference value, and if it exceeds the inspection reference value, it is detected as a defect.

  According to the above configuration, when the liquid crystal panel is inspected, the liquid crystal panel is imaged by the imaging unit while irradiating light from the inspection illumination device toward the black-displayed liquid crystal panel. Here, when a defect that always transmits light occurs in the liquid crystal panel, light leaks from the defective portion even though black is displayed. This transmitted light is filtered to the corresponding color by the color filter, and then filtered again by the correction color filter before reaching the imaging means. By this correction color filter, the sensitivity characteristic with respect to the wavelength in the visible light region in the imaging unit is corrected to be flat. Therefore, even when the defect generated in the liquid crystal panel is such that the color changes in accordance with the relative positional relationship between the defect and the imaging means, the defect can be reliably detected.

The following configuration is preferable as an embodiment of the present invention.
(1) The correction color filter is installed at a position separated from both the image pickup means and the liquid crystal panel. This facilitates the work when replacing the correction color filter.

(2) The correction color filter is supported in a posture inclined with respect to the plate surface of the liquid crystal panel. As a result, it is possible to avoid a situation in which the light from the inspection illumination device is reflected by the correction color filter and reflected on the liquid crystal panel, so that an accurate inspection can be expected.

(3) The defect detection unit is configured by an arithmetic processing unit that performs a smoothing process and a noise removal process on the light reception signal output from the imaging unit, and adds a binarization process. Thereby, a more accurate inspection can be expected.

(4) A determination signal output based on the binarization process is input from the arithmetic processing unit, and a monitor capable of displaying a determination result based on the determination signal is provided. Thereby, an operator can confirm an inspection result by visual observation.

(5) The liquid crystal panel in the normally black mode is inspected. This eliminates the need to give an inspection signal to the liquid crystal panel when performing the inspection, thereby simplifying the inspection apparatus.

  According to the present invention, it is possible to prevent inspection leakage.

<Embodiment>
An embodiment of the present invention will be described with reference to FIGS. In the present embodiment, an inspection device 30 for lighting inspection performed in the manufacturing process of the liquid crystal display device 10 will be described. In the following, the vertical direction is based on FIG.

  First, the structure of the liquid crystal display device 10 will be described. As shown in FIG. 1, the liquid crystal display device 10 roughly includes a liquid crystal panel 11 for displaying an image, and a backlight 12 that is an external light source disposed on the lower side (back side) of the liquid crystal panel 11. It is set as the structure assembled | attached mutually. The liquid crystal panel 11 is held in a state of being sandwiched between a backlight 12 on the back side thereof and a bezel 13 having a substantially frame shape arranged on the upper side (front side).

  The backlight 12 includes a substantially box-shaped case 14 that opens toward the upper side (the front side, the liquid crystal panel 11 side), and a plurality of linear light sources 15 that are accommodated in the case 14 so as to be arranged in parallel to each other. For example, a cold cathode tube), a plurality of optical sheets 16 (for example, a diffusion plate, a diffusion sheet, a lens sheet, and a brightness enhancement sheet in order from the back side) arranged in a stacked state in the opening of the case 14, and these optical sheets 16 It is comprised from the substantially frame-shaped flame | frame 17 for pinching | interposing a group between cases 14 and hold | maintaining. Each optical sheet 16 has a function of converting light emitted from each linear light source 15 into a planar shape.

  The liquid crystal panel 11 generally has a rectangular shape as a whole, and is sandwiched between a pair of transparent (translucent) glass substrates 18 and 19 and both the substrates 18 and 19 and an electric field. And a liquid crystal 20 which is a substance whose optical characteristics change with application. Both substrates 18 and 19 are bonded to each other with a predetermined gap (gap) therebetween by a spacer (not shown), and the liquid crystal 20 sandwiched therebetween is surrounded by a sealant 21 and is liquid-tight. Kept in a state. Also, a pair of front and back polarizing plates 22 and 23 are attached to the outer surface sides (surfaces opposite to the liquid crystal 20 side) of both substrates 18 and 19, respectively. The thickness dimension of both the substrates 18 and 19 is, for example, about 700 μm, whereas the thickness dimension of the layer of the liquid crystal 20 is, for example, about 3 to 5 μm.

  The two substrates 18 and 19 are the CF substrate 18 on the upper side (front side) and the array substrate 19 on the lower side (back side). A large number of switching elements (for example, TFTs) and pixel electrodes are provided side by side on the inner surface side (the liquid crystal 20 side, the side facing the CF substrate 18) of the array substrate 19, and these switching elements and pixel electrodes (pixels). A source wiring and a gate wiring having a lattice shape are arranged around the gate. In the vicinity of the edge of the array substrate 19, a terminal portion of each wiring is provided, and a driver connected to an external circuit that supplies an image signal to the terminal portion is crimped.

  On the other hand, on the inner surface side (the liquid crystal 20 side, the surface facing the array substrate 19) of the CF substrate 18, as shown in FIG. 2, a transparent counter electrode 24 facing the pixel electrode on the array substrate 19 side is provided. In addition, a large number of color filters 25 are arranged side by side at positions corresponding to the respective pixels. The color filter 25 has a function of filtering light emitted from the backlight 12 and allowing transmission of light having a specific wavelength. The color filter 25 is arranged so that three colors corresponding to three colors of R (red), G (green), and B (blue) are alternately arranged. Between the color filters 25, a black matrix 26 made of a light shielding material for preventing light leakage is provided. The color filter 25 has a rectangular shape in plan view, and its long side is about 600 μm, for example, while its short side is about 200 μm, for example. In the following description, when distinguishing the color filter 25, a red suffix is added to the red code, a suffix G is added to the green code, and a blue suffix is added to the blue code. In this case, no suffix is added to the reference sign.

  Further, the liquid crystal panel 11 is of a so-called normally black mode in which black is displayed with a minimum light transmittance when no signal is applied to each wiring and no electric field is applied to the liquid crystal 20. Yes.

  In the process of manufacturing the liquid crystal panel 11 having the above-described configuration, various inspections are performed to check whether the liquid crystal panel 11 is defective. As one of the inspections, there is a lighting inspection for inspecting the liquid crystal panel 11 for various defects. Next, the inspection device 30 used for lighting inspection will be described.

  As shown in FIG. 3, the inspection device 30 is arranged on the upper side (front side) of the liquid crystal panel 11 and can image the liquid crystal panel 11, and is arranged on the back side of the liquid crystal panel 11 and the liquid crystal panel. 11, a test backlight 32 that can irradiate light, an arithmetic processing unit 33 that is connected to the camera 31 and arithmetically processes a received light signal input from the camera 31, and a monitor that is connected to the arithmetic processing unit 33 34, and a correction color filter 35 disposed between the liquid crystal panel 11 and the camera 31.

  The camera 31 incorporates a CCD area sensor as an image sensor. The camera 31 is a so-called monochrome camera that does not have color identification capability. Although not shown, a total of four cameras 31 are installed side by side, and each camera 31 can divide the screen of the liquid crystal panel 11 into four regions and take an image. This camera 31 has a predetermined sensitivity characteristic with respect to the wavelength in the visible light region. For example, even when R, G, and B light have the same light amount, B, G, and R have high intensities in this order. It tends to detect (brighter) light. The camera 31 can output a light reception signal to the arithmetic processing unit 33 during imaging.

  The inspection backlight 32 has a configuration similar to that of the backlight 12 constituting the liquid crystal display device 10, and although not shown in detail, a large number of linear light sources (for example, a cold light source) are provided in a substantially box-shaped case whose upper surface is open. A plurality of optical sheets are stacked on the upper surface side of the case, and planar light can be irradiated as a whole.

  The arithmetic processing unit 33 has a function of determining the presence / absence of a defect by applying predetermined arithmetic processing to the light reception signal output from the camera 31. Specifically, the arithmetic processing unit 33 performs preprocessing such as smoothing processing and noise removal processing on the received light reception signal, and then adds binarization processing. The obtained detection value is a predetermined value. If it exceeds the threshold value, that is, the inspection reference value, it is determined that there is a defect, and it is determined as NG. If it is lower, it is determined that there is no defect, it is determined as OK, and the determination signal is output to the monitor 34. The monitor 34 can display a determination result of “OK” or “NG” based on the determination signal output from the arithmetic processing unit 33.

  Next, the correction color filter 35 interposed between the liquid crystal panel 11 and the camera 31 will be described in detail. The correction color filter 35 is for correcting the sensitivity characteristic with respect to the wavelength of the visible light region in the camera 31 to be flat. Specifically, as shown in FIG. 4, the color in the liquid crystal panel 11 is corrected. When the light of each color transmitted through the filter 25 has the same amount of light, the camera 31 is set to perform filtering so that the light can be detected as light of the same intensity. In other words, in the correction color filter 35, the ratio between the original light amount (the light amount before passing through the correction color filter 35) and the intensity of the light detected by the camera 31 is the same regardless of the color of the light. To be filtered. More specifically, the correction color filter 35 is set so that the amount of light to be filtered increases in the order of B, G, and R, that is, the order in which the camera 31 detects with high intensity. In FIG. 4, the left side of FIG. 4 represents the light amounts of the R, G, and B colors before passing through the correction color filter 35, and the right side of FIG. 4 is detected by the camera 31 after passing through the correction color filter 35. The light intensity of each of the R, G, and B colors is shown.

  The correction color filter 35 is suspended from the camera 31 by an attachment (not shown), and is fixedly supported at a position spaced downward from the camera 31 and spaced upward from the liquid crystal panel 11. Thereby, compared with the case where the correction color filter is provided integrally with the lens of the camera 31, for example, the replacement work of the correction color filter 35 is facilitated. Further, the correction color filter 35 is supported in an inclined posture with respect to the plate surface of the liquid crystal panel 11. As a result, it is possible to avoid a situation in which the light from the inspection backlight 32 is reflected by the correction color filter 35 and reflected on the liquid crystal panel 11.

  This embodiment has the structure as described above, and the operation thereof will be described subsequently. When the liquid crystal panel 11 is manufactured, a switching element, a pixel electrode, and the like are formed on the array substrate 19 side by a known method, while a color filter 25, a counter electrode 24, and the like are formed on the CF substrate 18 side. 18 and 19 are bonded together, and the liquid crystal 20 is injected between them. Thereafter, when the polarizing plates 22 and 23 are attached to the outer surface sides of both the substrates 18 and 19, respectively, the lighting inspection of the liquid crystal panel 11 is performed using the inspection device 30 having the above-described configuration.

  As shown in FIG. 3, when the liquid crystal panel 11 to be inspected is set at a predetermined position in the inspection apparatus 30, the liquid crystal panel 11 is imaged by the camera 31 while the inspection backlight 32 is turned on. At this time, imaging is performed in a state where no voltage is applied to each wiring, that is, in a black screen state, without connecting an external circuit to each wiring of the liquid crystal panel 11. At this time, the inspection backlight 32 may be always turned on or may be turned on only during imaging. Further, since the liquid crystal panel 11 to be inspected is in the normally black mode, it is not necessary to give an inspection signal to the liquid crystal panel 11. Thereby, simplification of the inspection apparatus 30 is realized.

  Here, when the defect which always permeate | transmits light has arisen in the liquid crystal panel 11, light leaks out to the camera 31 side by the defect. The transmitted light is filtered into a predetermined color through the color filter 25 in the liquid crystal panel 11, and then passes through the correction color filter 35 and then reaches the camera 31.

  The light reception signal output from the camera 31 along with the imaging is input to the arithmetic processing unit 33 and various arithmetic processes are performed. Then, the detected value of the intensity of the obtained light is compared with the inspection reference value, and if the detected value exceeds the inspection reference value, it is determined that there is a defect, and if not, the defect is determined not to exist, A determination signal corresponding to that is output. The monitor 34 displays a determination result of “OK” or “NG” based on the input determination signal. The operator can confirm the inspection result by viewing the monitor 34.

  By the way, the defect that always transmits light may be caused by the foreign matter X sandwiched between the CF substrate 18 and the polarizing plate 22 on the front side, as shown in FIG. In this case, since the foreign matter X is arranged at a position separated from the color filter 25 by the thickness of the CF substrate 18, the light that is visually recognized due to the foreign matter X varies depending on the viewing angle. The color filter 25 is transmitted. That is, in this type of defect (occurred outside the substrates 18 and 19), parallax occurs, and the color changes depending on the relative positional relationship between the foreign object X and the camera 31 in the plate surface direction of the liquid crystal panel 11. To do.

  Specifically, when the camera 31 is at the position indicated by the solid line in FIG. 5, the camera 31 detects blue light that has passed through the blue color filter 25 </ b> B located directly below the foreign object X. However, when the camera 31 is at the position indicated by the two-dot chain line in FIG. 5, the green light that has passed through the green color filter 25 </ b> G located on the diagonally lower left side of the foreign object X is detected by the camera 31. Similarly, when the camera 31 is in another position, the camera 31 may detect red light that has passed through the red color filter 25R. The brightness of the defect (the amount of light transmitted through the liquid crystal panel 11) depends on the size, shape, material, etc. of the foreign matter X. In addition to the above, a foreign matter sandwiched between the array substrate 19 and the polarizing plate 23 on the back side or a foreign matter attached to the surface of the polarizing plates 22 and 23 always transmits light and has a defect whose color changes depending on the viewing angle. Can cause

  If a correction color filter that matches the sensitivity characteristics of the camera 31 with human visual characteristics is used as in the prior art, for example, the light that has passed through the blue color filter 25B due to foreign matter X is converted into the conventional correction color. Even if it is detected by the camera 31 as light having an intensity lower than the detection reference value by passing through the filter, if the color of the light is green or red, it may exceed the detection reference value. Will result in inspection omission (see FIG. 6).

  In that respect, according to the inspection apparatus according to the present embodiment, the light transmitted through the liquid crystal panel 11 passes through the correction color filter 35 before reaching the camera 31, so that the light is transmitted as shown in FIG. Regardless of the color, the original light amount (the light amount before passing through the correction color filter 35) and the intensity detected by the camera 31 are filtered so that the ratio is the same. Even if it exists, it can detect as light of the same intensity. That is, since the sensitivity characteristic with respect to the wavelength of the visible light region in the camera 31 is corrected to be flat, whatever the color of the light reaching the camera 31 is surely exceeded for the inspection reference value. Can be detected. As a result, it is possible to prevent a conventional inspection leakage from occurring.

  As described above, according to the present embodiment, when the light of each color transmitted through each color filter 25 of the liquid crystal panel 11 has the same light amount, the light is filtered so that the camera 31 can detect the light as light having the same intensity. The correction color filter 35 is interposed between the camera 31 and the liquid crystal panel 11 so that the sensitivity characteristic with respect to the wavelength in the visible light region in the camera 31 is corrected to be flat. Even when the defect is such that the color changes in accordance with the relative positional relationship between the defect and the camera 31, the defect can be reliably detected, thereby preventing an inspection omission. it can.

  Further, since the correction color filter 35 is installed at a position separated from both the camera 31 and the liquid crystal panel 11, the work for replacing the correction color filter 35 is facilitated.

  Further, since the correction color filter 35 is supported in a posture inclined with respect to the plate surface of the liquid crystal panel 11, the light from the inspection backlight 32 is reflected by the correction color filter 35 and is reflected on the liquid crystal panel 11. The situation of reflection can be avoided and accurate inspection can be expected.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In the above-described embodiment, the inspection apparatus for inspecting the presence / absence of a defect has been exemplified. However, the present invention includes an apparatus that acquires defect position information.

  (2) In the above-described embodiment, the case where the inspection apparatus is used for the lighting inspection performed after the polarizing plate is attached is exemplified. However, the inspection apparatus is used for the lighting inspection performed at a stage before the polarizing plate is attached. May be. Even in such a case, it is effective to detect foreign matter adhering to the outer surface of the substrate.

  (3) In the above-described embodiment, the correction color filter is illustrated as being separated from the camera. However, the present invention also includes a correction color filter that is provided integrally with a camera lens or the like. included.

  (4) In the above-described embodiment, the correction color filter is supported by being inclined with respect to the plate surface of the liquid crystal panel. However, the correction color filter installed in parallel with the liquid crystal panel is also the present invention. include.

  (5) In the above-described embodiment, a case where a CCD area sensor is used as an image pickup element of a camera has been described. However, the present invention includes an image pickup element using another type of image pickup element such as a CMOS area sensor.

  (6) In the above-described embodiment, the case where the color filter of the liquid crystal panel to be inspected has three colors of R, G, and B has been described. However, C (cyan), M (magenta), and Y (yellow) The present invention is also applicable when inspecting a liquid crystal panel having three color filters.

  (7) In the above-described embodiment, the case of inspecting a normally black mode liquid crystal panel has been shown. However, the light transmittance is maximized when no signal is applied to each wiring and no electric field is applied to the liquid crystal. The present invention can also be applied to inspecting a so-called normally white mode liquid crystal panel that displays white.

Sectional drawing of the liquid crystal display device which concerns on one Embodiment of this invention Expanded sectional view of the liquid crystal panel Schematic representing the entire inspection device Explanatory diagram showing the relationship between the amount of light of each color before passing through the correction color filter and the intensity of light of each color detected by the camera after passing through the correction color filter Explanatory diagram regarding defects that cause parallax Explanatory drawing showing the relationship between the light quantity of each color before permeate | transmitting the conventional correction color filter, and the intensity | strength of the light of each color detected by the camera after permeate | transmitting the conventional correction color filter

Explanation of symbols

11 ... Liquid crystal panel 12 ... Backlight (external light source)
25 ... Color filter 30 ... Inspection device 31 ... Camera (imaging means)
32 ... Backlight for inspection (lighting device for inspection)
33 ... arithmetic processing unit (defect detection means)
34 ... Monitor 35 ... Color filter for correction

Claims (7)

An inspection device used to inspect a liquid crystal panel,
Imaging means for imaging the liquid crystal panel and outputting a light reception signal thereof;
An illumination device for inspection that irradiates light from the opposite side of the imaging means to the liquid crystal panel;
A correction color filter for correcting the sensitivity characteristic with respect to the wavelength of the visible light region in the imaging means to be flat;
A detection value obtained on the basis of the light reception signal output from the imaging means is compared with a predetermined inspection reference value, and a defect detection means for detecting a defect when the inspection reference value is exceeded is provided. A liquid crystal panel inspection device. The liquid crystal panel inspection apparatus according to claim 1, wherein the correction color filter is disposed at a position separated from both the imaging unit and the liquid crystal panel. The liquid crystal panel inspection apparatus according to claim 1, wherein the correction color filter is supported in a posture inclined with respect to a plate surface of the liquid crystal panel. 2. The defect detection unit includes an arithmetic processing unit that applies a binarization process after performing a smoothing process and a noise removal process on a light reception signal output from the imaging unit. The liquid crystal panel inspection apparatus according to claim 3. 2. A monitor, which receives a determination signal output from the arithmetic processing unit based on the binarization process and displays a determination result based on the determination signal. The liquid crystal panel inspection apparatus according to claim 4. 6. The liquid crystal panel inspection apparatus according to claim 1, wherein the liquid crystal panel in a normally black mode is inspected. An inspection method for a liquid crystal panel,
When the liquid crystal panel is irradiated with light by the inspection illumination device and the liquid crystal panel is picked up by the image pickup means from the opposite side, the correction color filter has a sensitivity characteristic with respect to the wavelength of the visible light region in the image pickup means. When the light is filtered to be flat and the detection value obtained by the defect detection means based on the received light signal output from the imaging means is compared with a predetermined inspection reference value, and the inspection reference value is exceeded Is a method for inspecting a liquid crystal panel, characterized in that it is detected as a defect.

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