JP4909672B2 - Liquid crystal panel inspection method and apparatus - Google Patents

Description

  The present invention relates to a liquid crystal panel inspection method and apparatus for illuminating a liquid crystal panel with a backlight and observing defects such as dust inside the liquid crystal panel with an imaging device.

The following Patent Document 1 and Patent Document 2 are known as a type of liquid crystal panel inspection apparatus that illuminates a liquid crystal panel with a backlight and observes defects such as dust inside the liquid crystal panel with an imaging device.
JP 11-326123 A JP-A-10-227721

  In the liquid crystal panel inspection apparatus of Patent Document 1, a backlight is disposed so as to face the lower surface of the liquid crystal panel, and a sensor camera is disposed so as to face the upper surface of the liquid crystal panel. Hereinafter, the side facing the sensor camera is referred to as a front surface, and the side facing the backlight is referred to as a back surface. By turning on the backlight and photographing the backlight light transmitted through the liquid crystal panel with a camera, the inside of the liquid crystal panel is inspected. In this case, not only defects inside the liquid crystal panel, but also scratches on the protective film attached to the surface of the liquid crystal panel and dust attached to the surface are photographed by the sensor camera. Therefore, in Patent Document 1, an inclined illumination lamp is used so that light can be applied to the front surface of the liquid crystal panel from an oblique direction so that an internal defect and surface dust can be distinguished. First, with the backlight turned off, only the tilted illumination light is irradiated onto the front surface of the liquid crystal panel, and the reflected light is photographed with a sensor camera. At this time, the sensor camera shows scratches or dust on the surface of the liquid crystal panel, and no defects inside the liquid crystal panel are reflected. Next, the inclined illumination lamp is turned off, the backlight is turned on, and the transmitted light is photographed by the camera. At this time, the sensor camera shows both the defects inside the liquid crystal panel and the scratches and dust on the front side of the liquid crystal panel. Finally, by subtracting the photographed image information from the tilted illumination light from the photographed image information from the backlight, only the defects inside the liquid crystal panel can be obtained.

  The liquid crystal panel inspection apparatus of Patent Document 2 is the same as the apparatus of Patent Document 1. That is, the television camera is disposed so as to face the front surface of the liquid crystal panel, and the backlight is disposed so as to face the back surface of the liquid crystal panel. Before or after the lighting inspection with the backlight, the backlight is turned off, only the tilted illumination light is irradiated onto the front surface of the liquid crystal panel, and the reflected light is photographed with a television camera. At this time, what appears on the TV camera is scratches on the protective sheet on the front side of the liquid crystal panel and dust on the protective sheet (hereinafter referred to as surface defects), and no defects inside the liquid crystal panel are reflected. . On the other hand, in the lighting inspection, the inclined illumination lamp is turned off, the backlight is turned on, and the transmitted light is photographed by the camera. At this time, both the defects inside the liquid crystal panel and the surface defects of the liquid crystal panel are reflected on the television camera. The captured image information (reflected image information) by tilted illumination light and the captured image information (transmission image information) by backlight light are compared with each other in the coordinate position, and what is reflected in either captured image information is liquid crystal It can be determined that the surface defect of the panel, which is reflected only in the photographed image information by the backlight, is a defect inside the liquid crystal panel.

  The liquid crystal panel inspection apparatuses described in Patent Document 1 and Patent Document 2 described above have the following problems. In these prior arts, it is impossible to distinguish between dust adhering to the back side surface of the liquid crystal panel and defects inside the liquid crystal panel. That is, even if the illumination light is irradiated on the front surface of the liquid crystal panel, dust attached to the surface on the back surface side is not reflected in the camera image. On the other hand, when photographing with backlight, both surface dust on the back side of the liquid crystal panel and defects inside the liquid crystal panel appear as images, and thus cannot be distinguished.

  In addition, Patent Document 1 and Patent Document 2 described above are for inspecting the presence or absence of internal dust or the like for a liquid crystal panel provided with a polarizing plate, and nothing is touched on the liquid crystal panel before the polarizing plate is attached. . If it becomes clear that dust etc. has entered the inside of the liquid crystal panel at the stage before sticking the polarizing plate, there is no need to perform unnecessary work (such as sticking the polarizing plate) afterwards. Document 1 and Patent Document 2 do not mention what kind of device is necessary for inspecting internal dust or the like for a liquid crystal panel without a polarizing plate.

  An object of the present invention is to distinguish between images of dust adhering to the surfaces on both sides of a liquid crystal panel and defects inside the liquid crystal panel when inspecting a liquid crystal panel without a polarizing plate using an imaging device. And a liquid crystal panel inspection method and apparatus.

  The liquid crystal panel inspection method of the present invention includes the following steps (a) to (c). (A) In the state where no voltage is applied to the liquid crystal panel without the polarizing plate, one of the following steps (a1) and (a2) is performed, and then the other step is performed. Non-lighting inspection stage to carry out the stage. (A1) The first backlight disposed on the one surface of the liquid crystal panel so as to face the one surface is irradiated with the first backlight through the first illumination side polarizing plate, and the liquid crystal panel A first imaging stage in which the liquid crystal panel is imaged via a first imaging-side polarizing plate with a first imaging device arranged to face the other surface of the first imaging device. (A2) The first imaging device irradiates inclined illumination light onto the one surface from an inclined illumination light source arranged to illuminate the one surface with a predetermined inclination angle, and the first imaging device performs the first imaging. A second imaging step of imaging the liquid crystal panel through a side polarizing plate; (A3) A first defect detection stage that specifies a defect position of the liquid crystal panel based on the imaging result of the first imaging stage and the imaging result of the second imaging stage. (B) A lighting inspection stage in which the following stage (b1) is performed after the probe stage is in contact with the electrodes of the liquid crystal panel, and then the stage (b2) is performed. (B1) The second backlight is arranged so as to face the one surface, and the one surface is irradiated with the second backlight light through the second illumination side polarizing plate, and the other surface is faced. A third imaging stage in which the liquid crystal panel is imaged via the second imaging-side polarizing plate with the second imaging device arranged to be. (B2) A second defect detection stage that specifies a defect position of the liquid crystal panel based on the imaging result of the third imaging stage. (C) A determination step of determining, as a true defect position, a position where the defect position specified in the first defect detection step and the defect position specified in the second defect detection step overlap each other.

The non-lighting inspection stage described above is performed in the non-lighting inspection section, and the lighting inspection stage is performed in the lighting inspection section at a position different from the non-lighting inspection section. In that case, the first backlight, the first illumination-side polarizing plate, the first imaging device, and the first imaging-side polarizing plate are installed in the non-lighting inspection unit, and the second backlight and the second illumination. The side polarizing plate, the second imaging device, and the second imaging side polarizing plate are installed in the lighting inspection unit. In this case, the non-lighting inspection stage includes a first panel support that supports the liquid crystal panel, a first backlight, a first illumination-side polarizing plate, a first panel support that includes an inclined illumination light source, and a first imaging. It implements using the apparatus and the 1st imaging part provided with the 1st imaging side polarizing plate. The lighting inspection stage includes a second panel support that includes a second panel support that supports the liquid crystal panel, a second backlight, and a second illumination-side polarizing plate, a second imaging device, and a second imaging-side polarized light. It implements using the 2nd imaging part provided with the board. Then, after the non-lighting inspection stage is performed, the liquid crystal panel supported by the first panel receiver is transported to the second panel receiver using a transport means, and then the lighting inspection stage is performed. The

  The liquid crystal panel inspection apparatus of the present invention includes the following (a) to (c). (A) A non-lighting inspection unit including the following (a1) to (a8). (A1) A first panel support for supporting the liquid crystal panel. (A2) A first backlight arranged to face one surface of the liquid crystal panel. (A3) A first imaging device arranged to face the other surface of the liquid crystal panel. (A4) A first illumination-side polarizing plate disposed between the liquid crystal panel and the first backlight. (A5) A first imaging-side polarizing plate disposed between the liquid crystal panel and the first imaging device. (A6) An inclined illumination light source that applies illumination light to the one surface at a predetermined inclination angle, and the illumination light from the inclined illumination light source does not pass through the first illumination side polarizing plate. An inclined illumination light source arranged to hit the surface of (A7) A switching device for switching between illumination of the liquid crystal panel by the first backlight and illumination of the liquid crystal panel by the inclined illumination light source. (A8) An imaging result obtained by imaging the liquid crystal panel with the first imaging device under illumination by the first backlight, and the liquid crystal panel with the first imaging device under illumination by the tilted illumination light source. 1st defect detection means which specifies the defect position of the said liquid crystal panel based on the imaged imaging result. (B) A lighting inspection unit including the following (b1) to (b7). (B1) A probe unit including a probe needle that can contact the electrode of the liquid crystal panel. (B2) A second panel support for supporting the liquid crystal panel. (B3) A second backlight arranged so as to face the one surface. (B4) A second imaging device arranged to face the other surface. (B5) A second illumination-side polarizing plate disposed between the liquid crystal panel and the second backlight. (B6) A second imaging-side polarizing plate disposed between the liquid crystal panel and the second imaging device. (B7) Second defect detection means for specifying a defect position of the liquid crystal panel based on an imaging result obtained by imaging the liquid crystal panel with the second imaging device under illumination by the second backlight. (C) A determination unit that determines a position where a defect position specified by the first defect detection unit and a defect position specified by the second defect detection unit overlap each other as a true defect position.

  The present invention has an effect that when a liquid crystal panel without a polarizing plate is inspected by using an imaging device, an image of dust attached to both surfaces of the liquid crystal panel can be distinguished from defects inside the liquid crystal panel. Play.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing an overall image of an embodiment of the liquid crystal panel inspection apparatus of the present invention, and a part thereof is shown in a sectional view. The liquid crystal panel inspection apparatus includes a non-lighting inspection unit 10 and a lighting inspection unit 11 at a position different from the non-lighting inspection unit 10 . The non-lighting inspection unit 10 is a device part that inspects the liquid crystal panel in a state where no voltage is applied to each cell of the liquid crystal panel (non-lighting state). The lighting inspection unit 11 is an apparatus portion that inspects the liquid crystal panel in a state where a voltage for displaying a predetermined display pattern or the like is applied to each cell (lighting state). After defect inspection (internal dust inspection) by the non-lighting inspection unit 10, the liquid crystal panel 16 is transported to the lighting inspection unit 11, and defect inspection is performed by lighting inspection.

  FIG. 2 is a front view of the non-lighting inspection section, and a part thereof is shown in a cross-sectional view. The non-lighting inspection unit includes a first panel support unit 12 positioned below and a first imaging unit 13 positioned above.

  The first panel support unit 12 has a function of supporting the liquid crystal panel 16 and irradiating illumination light from below the liquid crystal panel 16. The first panel support 12 includes a first alignment stage 18, a first backlight 20, a work table base 22 (hereinafter, a work table is abbreviated as WT), a first WT block 24, an inclined illumination light source 26 and a first. Panel receiver 28 is provided. The first backlight 20 is fixed to the upper surface of the first alignment stage 18. The WT base 22 is fixed to the first alignment stage 18 by a plurality of support columns 30. A rectangular through hole 32 is formed in the center of the WT base 22, and a first diffusion plate 34 is fixed so as to cover the through hole 32. A first illumination side polarizing plate 36 is arranged on the upper surface of the first diffusion plate 34. The first WT block 24 is fixed on the WT base 22. A rectangular through hole 38 is formed at the center of the first WT block 24, and a central opening 39 is formed by the through hole 38. An illumination arrangement space 40 is formed in the first WT block 24, and the inclined illumination light source 26 is arranged in the illumination arrangement space 40. A reflector 42 is disposed between the illumination arrangement space 40 and the central opening 39. A first panel receiver 28 is fixed around the through hole 38 on the upper surface of the first WT block 24. The liquid crystal panel 16 in a state before the polarizing plate is attached is supported on the upper surface of the first panel receiver 28.

  The first imaging unit 13 includes a first CCD camera 48 (first imaging device) and a first imaging side polarizing plate 50. The first imaging side polarizing plate 50 is disposed below the first CCD camera 48. The output signal of the first CCD camera 48 is subjected to image processing by the image processing unit 54 and displayed on the display unit 56 (image display).

  A plurality of air blowing devices 52 (air blowing devices) are disposed above the first panel support portion 12. The air blowing device 52 blows air from the oblique direction to the surface of the liquid crystal panel 16 to blow off dust and the like on the surface of the liquid crystal panel 16.

  FIG. 3 is an enlarged view of a portion A in FIG. The first panel receiver 28 is provided with a pusher roller 60, and the pusher roller 60 can press the side surface of the liquid crystal panel 16 rightward in FIG. The reflection plate 42 has an inner surface (right surface in FIG. 3) as a reflection surface, and the light of the first backlight is reflected by the reflection surface and reaches the liquid crystal panel 16. If the reflection plate 42 is not present, the illuminance of the backlight light is lower in the peripheral portion of the liquid crystal panel 16 than in the central portion. However, if the reflection plate 42 is present, such a decrease in illuminance can be prevented. The reflector 42 can rotate around the rotation axis 62 within an angle range of about 90 degrees. When the reflecting plate 42 is rotated 90 degrees counterclockwise around the rotation shaft 62 from the state of FIG. The reflecting plate 42 is in a horizontal state, and the illumination arrangement space 40 opens toward the central opening 39. When the inclined illumination light source 26 is turned on in this state, the inclined illumination light is irradiated obliquely on the lower surface of the liquid crystal panel 16. Therefore, the reflection plate 42 also functions as a shutter between the inclined illumination light source 26 and the liquid crystal panel 16.

  FIG. 4 is an enlarged view of a portion B in FIG. Part B discloses substantially the same structure as part A (FIG. 3). The only difference is as follows. The first panel receiver 28 is provided with a guide roller 62, and the liquid crystal panel 16 pushed by the pusher roller 60 (FIG. 3) is received by the opposite guide roller 62. Thereby, the liquid crystal panel 16 is positioned on the first panel receiver 28.

  FIG. 5 is a perspective view showing the structure of the WT base 22 and the upper part of the panel support portion, with a part cut away. Four first WT blocks 24 are fixed to the upper surface of the WT base 22 that is rectangular in plan view. An inclined illumination light source 26 and a reflector opening / closing mechanism 64 are arranged inside each first WT block 24. Four sets of the inclined illumination light sources 26 are arranged so as to correspond to the four sides of the rectangular liquid crystal panel. Covers 66 are attached to both side surfaces of the first WT block 24 to cover the illumination arrangement space inside the first WT block 24. The reflector opening / closing mechanism 64 can rotate the reflector 42 within an angle range of about 90 degrees. When the four reflecting plates 42 are in an upright state, a side wall surrounding the central opening 39 is formed, and the side wall serves as a reflecting surface of the backlight light. The first panel receiver 28 is provided with a pusher roller 60 and a guide roller 62.

  FIG. 6 is an enlarged view of a portion C in FIG. The reflector opening / closing mechanism 64 includes an electric motor 68 and a reflector support 70. The output shaft of the electric motor 68 extends in the horizontal direction, and the reflector support 70 is fixed thereto. A reflection plate 42 is fixed to the reflection plate support 70. When the output shaft of the electric motor 68 rotates within a range of about 90 degrees, the reflector support 70 rotates, and the reflector 42 rotates (opens and closes).

  FIG. 7 is a perspective view showing a state in which the four reflecting plates 42 are closed. The four reflecting plates 42 are upright, and the central opening 39 is surrounded by the four reflecting plates 42.

  FIG. 8 is a perspective view showing a state in which the four reflecting plates 42 are opened. The four reflecting plates 42 are rotated approximately 90 degrees outward from the state of FIG. 7 and are in a substantially horizontal state. The central opening 39 is in a state connected to the illumination arrangement space 40 (see FIG. 3).

  Next, a method for inspecting a defect (inside dust) of the liquid crystal panel in the non-lighting inspection unit will be described. FIG. 9 is a front view showing an optical path when the first backlight 20 illuminates the lower surface of the liquid crystal panel 16 and the liquid crystal panel 16 is observed by the first CCD camera 48. The reflector 42 is closed (upright). The backlight switch 72 is closed, and the output of the first backlight power supply 74 is supplied to the first backlight 20. The tilt illumination switch 76 is open, and the output of the tilt illumination power supply 78 is not supplied to the tilt illumination light source 26. The switch 72 for backlight and the switch 76 for inclined illumination correspond to the switching device in the present invention. The light 80 from the first backlight 20 passes through the first diffusion plate 34 and the first illumination side polarizing plate 36 and reaches the lower surface of the liquid crystal panel 16. The light 82 reflected by the reflecting plate 42 also reaches the lower surface of the liquid crystal panel 16. The action of the reflecting plate 42 prevents the illuminance near the periphery of the liquid crystal panel 16 from lowering than the center. The light 84 that has passed through the liquid crystal panel 16 passes through the first imaging-side polarizing plate 50 and reaches the first CCD camera 48.

  FIG. 10 is a front view showing an optical path when the lower surface of the liquid crystal panel 16 is illuminated obliquely with the inclined illumination light source 26 and the liquid crystal panel 16 is observed with the first CCD camera 48. The reflector 42 is open (almost horizontal). The tilt illumination switch 76 is closed, and the output of the tilt illumination power supply 78 is supplied to the tilt illumination light source 26. The backlight switch 72 is open, and the output of the first backlight power source 74 is not supplied to the first backlight 20. Light 86 from the inclined illumination light source 26 illuminates the lower surface of the liquid crystal panel 16 from an oblique direction. The light 84 that has passed through the liquid crystal panel 16 passes through the first imaging-side polarizing plate 50 and reaches the first CCD camera 48.

  FIG. 11 schematically shows a light scattering state by dust in the state of FIG. The liquid crystal panel 16 is in a state where no signal is input to the electrode (non-lighting state). Considering a liquid crystal device composed of two polarizing plates 36 and 50 and the liquid crystal panel 16, this liquid crystal device is in a mode for blocking the passage of light (light shielding mode). At this time, when the liquid crystal panel 16 is irradiated with the backlight light 80, the entire liquid crystal panel 16 looks dark when viewed from the first CCD camera 48. The reason is as follows. When the backlight light 80 passes through the first diffusion plate 34 and the first illumination side polarizing plate 36, it becomes a linearly polarized light 88 that vibrates only in one direction. The polarization axis of the linearly polarized light 88 is rotated by 90 degrees by the liquid crystal panel 16. Thus, the linearly polarized light whose polarization axis is rotated cannot pass through the first imaging-side polarizing plate 50. Therefore, when viewed as the entire liquid crystal device, the light shielding mode is set.

  When the above-mentioned linearly polarized light 88 hits the dust 90 inside the liquid crystal panel 16, that is, the dust 90 existing in the space between the two glass plates 92 and 94, the light is irregularly reflected and the polarization state changes. To do. Accordingly, part of the scattered light 96 from the dust 90 can pass through the first imaging-side polarizing plate 50, and this reaches the first CCD camera 48. As a result, dust 90 appears on the video as a bright spot. Similarly, with respect to the dust 98 attached to the back side surface of the liquid crystal panel 16, the light is scattered here, and the scattered light 100 appears as a bright spot. The scattered light 104 also appears as a bright spot on the dust 102 adhering to the front side surface of the liquid crystal panel 16. In this way, both the internal dust 90 (defects of the liquid crystal panel) of the liquid crystal panel 16 and the dusts 98 and 102 attached to the surface appear as bright spots on the image of the first CCD camera 48.

  The gap t2 between the two glass plates 92 and 94 is, for example, about 5 μm, and the maximum thickness of the internal dust 90 is also about 5 μm. On the other hand, the size t1 of the dust 98, 102 on the back surface or the front surface of the liquid crystal panel 16 is, for example, about several tens of μm and is three-dimensional. When illuminated with the backlight light 80, any dust 90, 98, 102 reflects light irregularly and appears as a bright spot on the image of the CCD camera 44.

  FIG. 12 schematically shows a light scattering state by dust in the state of FIG. The liquid crystal panel 16 is in a non-lighting state as in the case of FIG. When the inclined illumination light source 26 irradiates light 86 on the back surface of the liquid crystal panel 16 from an oblique direction, the intensity of the scattered light 96 due to the dust 90 inside becomes weak, and the intensity of the bright spot reflected on the first CCD camera 48 is become weak. The reason is as follows. As described above, the gap t2 between the two glass plates 92 and 94 is about 5 μm, and the dust 90 in the glass plate 92 and 94 has a maximum thickness of about 5 μm. When such thin dust 90 is irradiated with light from an oblique direction, the intensity of the light 96 scattered in the direction of the first CCD camera 48 becomes weak. On the other hand, the dust 98, 102 on the back surface or the front surface of the liquid crystal panel 16 has a size of, for example, about several tens of μm and is three-dimensional. The light 100 and 104 scattered by the dusts 98 and 102 appears as bright spots on the image of the first CCD camera 48. In order to project only the dust on the surfaces on both sides of the liquid crystal panel without reflecting the dust inside the liquid crystal panel (that is, by reducing the intensity of scattered light toward the camera), the light 86 emitted from the inclined illumination light source 26 And the angle between the liquid crystal panel 16 and the back surface is preferably within a range of 10 to 50 degrees.

  Since the light 86 of the tilted illumination light source 26 is irradiated obliquely with respect to the back surface of the liquid crystal panel 16, the light transmitted through the liquid crystal panel 16 does not go directly to the first imaging-side polarizing plate 50. The transmitted light is not reflected on the first CCD camera 48. Of the light scattered by the dusts 90, 98, and 102, light that matches a specific polarization direction passes through the first imaging-side polarizing plate 50 and reaches the first CCD camera 48.

  FIG. 13A is an enlarged schematic view showing a part of the image of the liquid crystal panel taken by illuminating with the backlight 80 as shown in FIG. The lines extending in the vertical direction and the horizontal direction are the gate line 106 and the data line 108. A region surrounded by two adjacent gate lines 106 and two adjacent data lines 108 is one pixel. Internal dust inside the liquid crystal panel appears as a bright spot 110, and external dust attached to the front or back surface of the liquid crystal panel also appears as bright spots 112 (in this example, there are three). The positions of these bright spots 110 and 112 are stored in the memory.

  FIG. 13B is a schematic image view similar to FIG. 13A taken by illuminating with the inclined illumination light 86 as shown in FIG. The intensity of the bright spot 110 for the internal dust of the liquid crystal panel is reduced. The bright spot 112 of the external dust attached to the front or back surface of the liquid crystal panel has a high strength. If only the intensity of light above a predetermined threshold is taken out as meaningful data, the bright spot 110 due to internal dust disappears in terms of data. Only the position of the bright spot 112 of the external dust is stored in the memory.

  The data processing unit compares the data on the positions of the bright spots 110 and 112 in FIG. 13A with the data on the position of the bright spots 112 in FIG. Point). Thereby, as shown in FIG. 14, only the position data (defect position) of the bright spot 110 of the internal dust remains. If there is no internal dust, the defect location data does not remain. In this way, the defect inspection of the liquid crystal panel by the non-lighting inspection is completed.

  Next, the lighting inspection unit 11 in FIG. 1 will be described. FIG. 15 is a front view of the lighting inspection part, and a part thereof is shown in a sectional view. The lighting inspection unit includes a second panel support unit 12a positioned below, a second imaging unit 13a positioned above, and a probe unit 14 positioned therebetween.

  The second panel support portion 12 a has a function of supporting the liquid crystal panel 16 and irradiating illumination light from below the liquid crystal panel 16. The second panel support 12a includes a second alignment stage 18a, a second backlight 20a, and a second WT block 24a. The second backlight 20a is fixed to the upper surface of the second alignment stage 18a. The second WT block 24a is fixed to the second alignment stage 18a by a plurality of support columns 30a. Compared with the first WT block 24 for non-lighting inspection shown in FIG. 2, the second WT block 24 a has a higher rigidity because there is no inclined illumination space, and sufficiently withstands the needle pressure of the probe needle 46. be able to. A rectangular through hole 38a is formed at the center of the second WT block 24a, and a central opening 39a is formed by the through hole 38a. A second diffusion plate 34a is fixed to the step in the center in the height direction of the through hole 38a. A second illumination side polarizing plate 36a is disposed on the upper surface of the second diffusion plate 34a. The upper surface of the second WT block 24a serves as a second panel receiver, and this portion can support the liquid crystal panel 16 in a state before the polarizing plate is attached. The second panel receiver is also provided with a pusher roller and a guide roller in the same manner as the non-lighting test panel receiver 28 shown in FIG.

  The probe unit 14 includes a plurality of probe blocks 44, and each probe block 44 includes a plurality of probe needles 46. When performing a lighting test of the liquid crystal panel, the second alignment stage 18 a is raised to bring the probe needle 46 into contact with the electrode of the liquid crystal panel 16. A lighting signal is supplied from the signal generator 58 to the probe unit 14.

  The second imaging unit 13a includes three second CCD cameras 48a, 48b, and 48c (second imaging device), and second imaging-side polarizing plates 50a, 50b, and 50c corresponding to the cameras. These polarizing plates are arranged below the three second CCD cameras.

  A plurality of air blow devices 52a are arranged above the second panel support portion 12a. The air blowing device 52 a blows air from the oblique direction to the surface of the liquid crystal panel 16 and blows off dust and the like placed on the surface of the liquid crystal panel 16.

  The output signals of the three second CCD cameras 48a, 48b, and 48c are subjected to image processing by the image processing unit 54 and displayed on the display unit 56 (image display). FIG. 16 is a plan view showing an imaging range of three second CCD cameras. For the liquid crystal panel 16, the camera 48a covers the left imaging range 114a, the camera 48b covers the central imaging range 114b, and the camera 48c covers the right imaging range 114c. That is, the imaging ranges 114a, 114b, and 114c of the three cameras each cover approximately one third of the area of the liquid crystal panel 16, and these imaging ranges partially overlap each other. In the lighting inspection, the resolution can be increased by using three cameras, and the image of each pixel can be distinguished and recognized.

  In the lighting inspection unit shown in FIG. 15, the probe needle 46 is brought into contact with the electrode of the liquid crystal panel 16 to display a predetermined display pattern, and the lighting inspection is performed. Point) inspection, dark dot (black dot) inspection, display unevenness inspection, line defect inspection, and the like. Relevant to the present invention is the inspection of bright spots. At the stage of the non-lighting inspection described above, the presence of the internal dust and the position thereof are already inspected by inspecting the bright spot, but the bright spot is also inspected in the lighting inspection.

  In order to inspect the lighting of the liquid crystal panel by the lighting inspection unit of FIG. 15, the second alignment stage 18a is raised and the probe needle 46 is brought into contact with the electrode of the liquid crystal panel 1, and a predetermined pattern signal corresponding to the inspection item is generated. Apply to the cell. In order to inspect the bright spot, the screen needs to be a black screen, so an application pattern that does not apply a voltage to all cells is used. Then, the second backlight 20a is turned on and the liquid crystal panel is photographed by the three cameras 48a, 48b, and 48c. In this case, both the dust on the outside of the liquid crystal panel and the dust on the inside are reflected as bright spots. FIG. 17A is a schematic diagram showing an enlarged part of the video at that time. Internal dust inside the liquid crystal panel appears as bright spots 116, and external dust attached to the front or back surface of the liquid crystal panel also appears as bright spots 118 (three in this example). The positions of these bright spots 116 and 118 are stored in the memory.

  In the inspection at the non-lighting inspection part, the position (defect position) of the internal dust is obtained, so the bright spot positions 116 and 118 in FIG. The position where the position (the position of the bright spot 110 in FIG. 14) overlaps (the position of the bright spot 116) is the position of the internal dust (the true defect position). The other bright spots can be determined to be bright spots caused by external dust. The data processing unit automatically makes such a determination. The true defect position described above is shown as a bright spot 116 in FIG.

  The reason why the position of the internal dust is obtained again in the lighting inspection although the position of the internal dust is already obtained in the non-lighting inspection is as follows. This is because the accuracy of the defect position is low in the non-lighting inspection, whereas the accuracy of the defect position is high in the lighting inspection. In the non-lighting inspection, as shown in FIG. 2, one CCD camera 48 is used, and the image position resolution (internal dust position accuracy) may be larger than the pixel pitch. In this case, even if the internal dust is present at any one of the pixels, an area occupied by a plurality of pixels including surrounding pixels is recognized as a bright spot. In FIG. 13, the position of the internal dust 110 is drawn so that it can be recognized as the position of one pixel. However, actually, even if the internal dust exists only in one pixel, as described above. It may be recognized as the position of a plurality of pixels. On the other hand, in the lighting inspection, as shown in FIG. 15, three CCD cameras 48a, 48b, and 48c are used, and the position resolution of the image is the same as or smaller than the pixel pitch. . Internal dust position data consisting of multiple pixel positions obtained by non-lighting inspection, and dust position data consisting of single pixel positions obtained by lighting inspection (external dust position and internal dust position) Only the internal dust remains, and the position of a single pixel can also be obtained for the internal dust. In this way, the presence / absence and the position (defect position) of the internal dust on the liquid crystal panel can be determined with high accuracy at the individual pixel level while being distinguished from the external dust.

  Next, the entire procedure of the internal dust inspection method using both the non-lighting inspection and the lighting inspection will be described. First, in FIG. 2, the liquid crystal panel 16 is placed on the first panel receiver 28, and dust on the surface of the liquid crystal panel 16 is blown off as much as possible by the air blowing device 52. Next, as shown in FIG. 11, the lower surface of the liquid crystal panel 16 is illuminated by the first backlight 20, and the image of the liquid crystal panel 16 is recorded by the first CCD camera 48. At this time, the positions of the bright spots 110 and 112 as shown in FIG. Next, as shown in FIG. 12, the lower surface of the liquid crystal panel 16 is illuminated obliquely with the inclined illumination light source 26, and the image of the liquid crystal panel is recorded with the first CCD camera 48. At this time, as shown in FIG. 13B, the position of the bright spot 112 having a high intensity and the position of the bright spot 110 having a low intensity are obtained. If processing is performed with a predetermined threshold, only the position of the bright spot 112 having a strong intensity remains. When the data of the bright spot position obtained by the inclined illumination is removed from the bright spot position data obtained by the backlight illumination, only the bright spot 110 position of the internal dust remains as shown in FIG. . In this way, the presence / absence of internal dust, and the presence of internal dust, the defect position can be obtained.

  Next, as shown in FIG. 1, the liquid crystal panel 16 is transported from the first panel receiver of the non-lighting inspection unit 10 to the second panel receiver of the lighting inspection unit 11 using a transport device. Then, in the lighting inspection section shown in FIG. 15, the second air blow device 52a is used to blow off the dust on the liquid crystal panel 16 attached during transportation. Then, the bright spot is inspected with the liquid crystal panel 16 in a lighting inspection state. As a result, the positions of the bright spots 116 and 118 as shown in FIG. A position where the data of these positions overlaps with the data of the defect position of the internal dust obtained in the non-lighting inspection is defined as a true defect position.

It is a front view which shows the whole image of one Example of the liquid crystal panel test | inspection apparatus of this invention. It is a front view of a non-lighting inspection part. It is an enlarged view of the A section of FIG. It is an enlarged view of the B section of FIG. It is the perspective view which showed the structure of the WT base and its upper part among panel support parts. It is an enlarged view of the C section of FIG. It is a perspective view which shows the state which four reflecting plates closed. It is a perspective view which shows the state which four reflection plates opened. It is a front view which shows the optical path when illuminating the lower surface of a liquid crystal panel with a 1st backlight and observing a liquid crystal panel. It is a front view which shows the optical path when illuminating the lower surface of a liquid crystal panel from diagonally with an inclination illumination light source and observing a liquid crystal panel. FIG. 10 is a front view schematically showing a light scattering state by dust in the state of FIG. 9. It is a front view which shows typically the scattering state of the light by dust in the state of FIG. It is the schematic diagram which expanded and showed a part of image | video of a liquid crystal panel. It is another schematic diagram which expanded and showed a part of image | video of a liquid crystal panel. It is a front view of a lighting inspection part. It is a top view which shows the imaging range of three 2nd CCD cameras. It is another schematic diagram which expanded and showed a part of image | video of a liquid crystal panel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Non-lighting test | inspection part 11 Lighting test | inspection part 12 1st panel support part 13 1st imaging part 14 Probe part 16 Liquid crystal panel 18 1st alignment stage 20 1st backlight 22 WT base 24 1st WT block 26 Inclined illumination light source 28 1st 1 panel receiver 34 first diffuser plate 36 first illumination side polarizing plate 40 illumination arrangement space 42 reflector 44 probe block 46 probe needle 48 first CCD camera 50 first imaging side polarizing plate 52 air blow device 54 image processing unit 56 Display unit 58 Signal generator 64 Reflector opening / closing mechanism 72 Backlight switch 74 First backlight power supply 76 Inclined illumination switch 78 Inclined illumination power supply

Claims (7)

A liquid crystal panel inspection method comprising the following steps (a) to (c):
(A) In the state where no voltage is applied to the liquid crystal panel without the polarizing plate, one of the following steps (a1) and (a2) is performed, and then the other step is performed. Non-lighting inspection stage to carry out the stage.
(A1) The first backlight disposed on the one surface of the liquid crystal panel so as to face the one surface is irradiated with the first backlight through the first illumination side polarizing plate, and the liquid crystal panel A first imaging stage in which the liquid crystal panel is imaged via a first imaging-side polarizing plate with a first imaging device arranged to face the other surface of the first imaging device.
(A2) The first imaging device irradiates inclined illumination light onto the one surface from an inclined illumination light source arranged to illuminate the one surface with a predetermined inclination angle, and the first imaging device performs the first imaging. A second imaging step of imaging the liquid crystal panel through a side polarizing plate;
(A3) A first defect detection stage that specifies a defect position of the liquid crystal panel based on the imaging result of the first imaging stage and the imaging result of the second imaging stage.
(B) A lighting inspection stage in which the following stage (b1) is performed after the probe stage is in contact with the electrodes of the liquid crystal panel, and then the stage (b2) is performed.
(B1) The second backlight is arranged so as to face the one surface, and the one surface is irradiated with the second backlight light through the second illumination side polarizing plate, and the other surface is faced. A third imaging stage in which the liquid crystal panel is imaged via the second imaging-side polarizing plate with the second imaging device arranged to be.
(B2) A second defect detection stage that specifies a defect position of the liquid crystal panel based on the imaging result of the third imaging stage.
(C) A determination step of determining, as a true defect position, a position where the defect position specified in the first defect detection step and the defect position specified in the second defect detection step overlap each other. The liquid crystal panel inspection method according to claim 1, wherein the non-lighting inspection stage is performed in a non-lighting inspection section, and the lighting inspection stage is performed in a lighting inspection section at a position different from the non-lighting inspection section, The first backlight, the first illumination-side polarizing plate, the first imaging device, and the first imaging-side polarizing plate are installed in the non-lighting inspection unit, and the second backlight, the second illumination side A liquid crystal panel inspection method, wherein the polarizing plate, the second imaging device, and the second imaging-side polarizing plate are installed in the lighting inspection unit . The liquid crystal panel inspection method according to claim 2,
(A) In the non-lighting inspection stage, a first panel support unit including a first panel receiver that supports the liquid crystal panel, the first backlight, the first illumination-side polarizing plate, and the inclined illumination light source. And the first imaging device and the first imaging unit provided with the first imaging side polarizing plate,
(A) In the lighting inspection stage, a second panel support unit including a second panel receiver that supports the liquid crystal panel, the second backlight, and the second illumination side polarizing plate; and the second imaging. Implemented using a device and a second imaging unit comprising the second imaging side polarizing plate,
(C) After the non-lighting inspection step is performed, the liquid crystal panel supported by the first panel receiver is transported to the second panel receiver using a transport means, and then the lighting inspection step is performed. To be
A liquid crystal panel inspection method characterized by the above.   3. The liquid crystal panel inspection method according to claim 2, wherein the first imaging device includes one camera that images the entire liquid crystal panel, and the second imaging device includes a plurality of different regions on the liquid crystal panel. A method for inspecting a liquid crystal panel, comprising a plurality of cameras that respectively capture images. A liquid crystal panel inspection apparatus comprising the following (a) to (c).
(A) A non-lighting inspection unit including the following (a1) to (a8).
(A1) A first panel support for supporting the liquid crystal panel.
(A2) A first backlight arranged to face one surface of the liquid crystal panel.
(A3) A first imaging device arranged to face the other surface of the liquid crystal panel.
(A4) A first illumination-side polarizing plate disposed between the liquid crystal panel and the first backlight.
(A5) A first imaging-side polarizing plate disposed between the liquid crystal panel and the first imaging device.
(A6) An inclined illumination light source that applies illumination light to the one surface at a predetermined inclination angle, and the illumination light from the inclined illumination light source does not pass through the first illumination side polarizing plate. An inclined illumination light source arranged to hit the surface of
(A7) A switching device for switching between illumination of the liquid crystal panel by the first backlight and illumination of the liquid crystal panel by the inclined illumination light source.
(A8) An imaging result obtained by imaging the liquid crystal panel with the first imaging device under illumination by the first backlight, and the liquid crystal panel with the first imaging device under illumination by the tilted illumination light source. 1st defect detection means which specifies the defect position of the said liquid crystal panel based on the imaged imaging result.
(B) A lighting inspection unit including the following (b1) to (b7).
(B1) A probe unit including a probe needle that can contact the electrode of the liquid crystal panel.
(B2) A second panel support for supporting the liquid crystal panel.
(B3) A second backlight arranged so as to face the one surface.
(B4) A second imaging device arranged to face the other surface.
(B5) A second illumination-side polarizing plate disposed between the liquid crystal panel and the second backlight.
(B6) A second imaging-side polarizing plate disposed between the liquid crystal panel and the second imaging device.
(B7) Second defect detection means for specifying a defect position of the liquid crystal panel based on an imaging result obtained by imaging the liquid crystal panel with the second imaging device under illumination by the second backlight.
(C) A determination unit that determines, as a true defect position, a position where the defect position specified by the first defect detection unit and the defect position specified by the second defect detection unit overlap each other. 6. The liquid crystal panel inspection apparatus according to claim 5, further comprising the following (d) to (h).
(D) A first panel support section including the first panel receiver, the first backlight, and the first illumination side polarizing plate.
(E) A second panel support section including the second panel receiver, the second backlight, and the second illumination side polarizing plate.
(F) A first imaging unit that faces the first panel support unit and includes the first imaging device and the first imaging-side polarizing plate.
(G) A second imaging unit that faces the second panel support unit and includes the second imaging device and the second imaging-side polarizing plate.
(H) A transport device that transports the liquid crystal panel between the first panel support of the first panel support and the second panel support of the second panel support.   6. The liquid crystal panel inspection apparatus according to claim 5, wherein the first imaging device includes a single camera that images the entire liquid crystal panel, and the second imaging device includes a plurality of different regions on the liquid crystal panel. A liquid crystal panel inspection apparatus including a plurality of cameras that respectively capture images.

Images