JP2014202779A - Liquid crystal panel inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact liquid crystal panel inspection apparatus capable of rapidly and accurately identifying a defective address.SOLUTION: An inspection apparatus includes: first and second polarizers that are arranged above and below a liquid crystal panel on a worktable; a backlight unit that orthogonally illuminates the liquid crystal panel on the worktable from an undersurface of the liquid crystal panel through the second polarizer; an oblique illumination source that obliquely illuminates the liquid crystal panel on the worktable from a lower part of the undersurface; a probe unit that applies voltage to pixels of the liquid crystal panel on the worktable in order to inspect its lighting; an imaging device that images an upper surface of the liquid crystal panel through the first polarizer in a state of selectively receiving any one of the illumination light from the backlight unit and the oblique illumination light from the oblique illumination source; and reflection means that guides the oblique illumination light to the undersurface of the liquid crystal panel so that the oblique illumination light enters the liquid crystal panel at an appropriate incident angle.

Description

  The present invention relates to a liquid crystal panel inspection apparatus that illuminates a liquid crystal panel in which a polarizing plate is not incorporated with a backlight and photographs the image with an imaging apparatus, and determines a defect address of the liquid crystal panel from the image.

  There exists an inspection apparatus of patent document 1 in this kind of inspection apparatus. As shown in FIG. 7, the conventional inspection apparatus includes a non-lighting inspection unit A and a lighting inspection unit B. In the non-lighting inspection section A, the liquid crystal panel 1 in which no polarizing plate is incorporated is inspected in a non-lighting (non-driving) state in which no voltage is applied to each pixel. In the lighting inspection unit B, the liquid crystal panel 1 is inspected in a lighting (driving) state in which a voltage is applied to each pixel through the probe unit 2.

  In the non-lighting inspection section A, a pair of polarizing plates 4 a and 4 b are disposed above and below the liquid crystal panel 1 on the work table 3. The backlight source 5 irradiates light at a right angle to the lower surface 1b of the liquid crystal panel 1 through the lower polarizing plate 4b. A mirror 6 is held vertically on the work table 3, and a part of the light from the backlight source 5 is directed to the periphery of the liquid crystal panel 1 by the reflection of the mirror 6. The amount of light is increased.

  The liquid crystal panel 1 is photographed on the upper surface 1a by the imaging device 7 through the upper polarizing plate 4a while receiving the light from the backlight light source 5. The pair of polarizing plates 4a and 4b are arranged such that their polarization directions are parallel to each other. The light transmitted through the non-lighting liquid crystal panel 1 is rotated by 90 degrees in phase while transmitting. Therefore, as long as there is no scattering factor in the optical path passing through the liquid crystal panel 1, the light from the backlight source 5 that passes through the liquid crystal panel 1 is blocked from traveling by the polarizing plate 4a. As a result, the light from the backlight light source 5 is not captured by the imaging device 7, and a black screen is obtained by the imaging device 7. However, if there is a defect in the liquid crystal panel 1 or a foreign object is attached to the surfaces 1a and 1b of the liquid crystal panel 1, strong light from the backlight source 5 is scattered by the defect or the foreign object. Since part of the scattered light is transmitted through the polarizing plate 4a, the imaging device 7 observes the defect or foreign matter as a bright spot on the black screen.

  Since the foreign matter adhering to the surfaces 1a and 1b of the liquid crystal panel 1 can be removed by, for example, washing, it is necessary to remove the bright spot due to the foreign matter from the subject of consideration. For this purpose, the liquid crystal panel 1 is next subjected to a non-lighting inspection using the inclined illumination light source 8 in the same non-lighting inspection part A. In this non-lighting inspection, the inclined illumination light source 8 incorporated in the work table 3 is turned on instead of the backlight light source 5. Further, the mirror 6 is accommodated in a horizontal storage position indicated by a broken line in the non-lighting inspection portion A of FIG. 7 so as not to obstruct the light from the inclined illumination light source 8. The liquid crystal panel 1 on the work table 3 receives obliquely irradiated light from the inclined illumination light source 8 from the lower surface 1b without passing through the polarizing plate 4b. This obliquely irradiated light does not reach the image pickup device 6 directly, but is scattered by foreign matters attached to the surfaces 1a and 1b of the liquid crystal panel 1. However, the obliquely irradiated light from the inclined illumination light source 8 is not scattered as strongly as the foreign matter due to defects in the liquid crystal panel 1. As a result, on the black screen of the surface 1a of the liquid crystal panel 1 photographed by the imaging device 7 through the polarizing plate 4a under the inclined illumination light source 8, the brightness difference between the bright spot due to the foreign matter and the bright spot due to the defect is determined. Can be determined.

  Therefore, by comparing the bright spot data obtained in the non-lighting inspection section A under the backlight light source 5 and the bright spot data obtained in the non-lighting inspection section A under the tilted illumination light source 8, any bright spot data is obtained. It can be determined whether the point is a bright point due to a true defect (pixel defect).

  However, in both inspections in the non-lighting inspection section A described above, since a bright spot is displayed on the black screen, the pixel address of the bright spot determined to be due to a defect, that is, an accurate pixel address of the defect is obtained. It cannot be determined quickly.

  Therefore, in order to obtain the pixel address of the bright spot determined to be defective in both inspections in the non-lighting inspection part A, the liquid crystal panel 1 is applied with a voltage via the probe unit 2 in the lighting inspection part B. Inspected in the lighted (driven) state. In the lighting inspection section B, the liquid crystal panel 1 receives the light from the backlight light source 5 'through the polarizing plate 4b' similar to the polarizing plate 4b and passes through the polarizing plate 4a 'similar to the polarizing plate 4a to the imaging device 7. Taken by '. By this photographing, the defect and foreign matter are captured as black dots on the lighting screen of the liquid crystal panel 1, and a black matrix that partitions each pixel is captured on the lighting screen. Therefore, it is possible to easily read the address of the black spot corresponding to the bright spot due to the defect from the photographing screen of the imaging device 7 ', and thereby the pixel address of the true defect can be easily found.

  As a result, the defective pixel can be appropriately repaired based on the defective pixel address.

  However, in the above-described conventional liquid crystal panel inspection apparatus, installation space for configuring each inspection part is required for each of the non-lighting inspection part A and the lighting inspection part B, and the footprint becomes large. Further, it is necessary to transfer the liquid crystal panel 1 between the inspection parts A and B. In order to associate the bright spot obtained by the non-lighting inspection part A with the black spot obtained by the lighting inspection part B, the liquid crystal panel 1 Since accurate arrangement is required, it is disadvantageous in terms of shortening the line tact.

Japanese Patent Laid-Open No. 2008-40201

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a liquid crystal panel inspection apparatus that eliminates the above-mentioned drawbacks and is compact and can quickly and accurately identify a defective address of a liquid crystal panel.

  In order to prevent the problem of the conventional footprint and the transfer between both inspection parts A and B of the liquid crystal panel, it is conceivable to incorporate the probe unit 2 of the lighting inspection part B into the non-lighting inspection part A. However, even if the probe unit 2 of the lighting inspection unit B is simply incorporated in the non-lighting inspection unit A, the periphery of the liquid crystal panel 1 on the side opposite to the side where the inclined illumination light source is disposed depending on the oblique illumination from the inclined illumination light source 8 Appropriate oblique irradiation light does not sufficiently reach the area, and there is a case where the appropriate irradiation light is insufficient in the peripheral portion of the liquid crystal panel 1. This insufficient oblique irradiation light hinders quick and easy determination of bright spots in the non-lighting inspection section A under the inclined illumination light source 8.

  Therefore, in the present invention, in the non-lighting inspection under the inclined illumination light source light, in order to increase the oblique irradiation light in the peripheral portion of the liquid crystal panel, basically, the oblique inclination from the inclined illumination light source is placed in the work table. Reflection that guides a part of the oblique irradiation light to the peripheral part of the lower surface of the liquid crystal panel so that the irradiation light enters the liquid crystal panel at an appropriate incident angle without passing through the polarizing plate disposed below the liquid crystal panel. Means is provided.

  That is, the present invention is a liquid crystal panel inspection apparatus for inspecting a liquid crystal panel without a polarizing plate, and is a lifting table and a work table disposed on the lifting table and having a rectangular opening as a whole. A work table for receiving the edge of the liquid crystal panel by the frame body to hold the liquid crystal panel above the elevator, and first and first disposed above and below the liquid crystal panel on the work table. A first polarizing plate and a second polarizing plate, each of which is held in a predetermined relationship with each other, and the liquid crystal panel on the work table from the lower surface of the liquid crystal panel through the second polarizing plate. A backlight unit for irradiating the lower surface with light substantially perpendicular to the lower surface; an inclined illumination light source for irradiating the liquid crystal panel on the work table from an angle below the lower surface; A probe unit for applying a voltage to a pixel of the liquid crystal panel for lighting inspection of the liquid crystal panel at an ascending position, and the orthogonal illumination light from the backlight unit and the oblique illumination light from the inclined illumination light source An imaging device for photographing the upper surface of the liquid crystal panel through the first polarizing plate in a state where either one is selectively received, and the oblique illumination light from the inclined illumination light source disposed in the work table. Reflecting means for guiding a part of the oblique irradiation light to the peripheral portion of the lower surface of the liquid crystal panel so as to be incident on the liquid crystal panel at an appropriate incident angle without passing through the second polarizing plate.

  According to the liquid crystal panel inspection apparatus according to the present invention, non-lighting inspection is performed under irradiation light from a backlight unit provided on a single lifting platform, and the inclined illumination is used instead of the irradiation light from the backlight. A non-lighting inspection can be performed under a light source, and a lighting inspection using the probe unit can be performed under irradiation light from a backlight unit. Therefore, it is possible to perform a series of inspections quickly without the need to transfer the liquid crystal panel from the non-lighting inspection part A to the lighting inspection part B as in the prior art, and there is no need for alignment in both inspection parts A and B. Become. Therefore, it is possible to quickly inspect with a compact apparatus configuration, and it is possible to shorten the tact time.

  Further, in the non-lighting inspection under the inclined illumination light source light, the reflection means causes the oblique irradiation light from the oblique illumination light source to enter the liquid crystal panel at an appropriate incident angle without passing through the second polarizing plate. In addition, a part of the oblique irradiation light is guided to the lower surface of the liquid crystal panel. Therefore, there is no shortage of obliquely irradiated light in the periphery of the liquid crystal panel in the non-lighting inspection under the inclined illumination light source light. Therefore, the problem due to the shortage of light quantity can be solved, and the bright spot can be quickly and easily determined by the non-lighting inspection under the inclined illumination light source light.

  In order to enable uniform oblique irradiation to the lower surface of the liquid crystal panel according to the size of the liquid crystal panel, the reflecting means can be supported rotatably about an axis supported by the work table. In addition, the reflecting means can be held at an appropriate angle by the operating means for rotating around the axis.

  The angle of the reflecting means can be adjusted by the actuating device so that an incident angle to the lower surface that is reflected by the reflecting means and enters the liquid crystal panel is set to 60 degrees or more and less than 90 degrees.

  The axis of the reflecting means can be arranged along one side of a pair of opposite sides of the rectangular opening of the work table, and the inclined illumination light source is placed on the other side of the pair of sides. Can be arranged to extend along. The reflecting means and the inclined illumination source may be arranged to make a pair with each other on each of the four sides of the rectangular opening.

  The reflecting means can be constituted by a reflecting mirror supported by the work table via a horizontal axis at the upper edge. In this case, the actuating device can be operatively coupled to the reflector to hold the reflector at the desired rise angle.

  The actuating device may include any one of a ball screw mechanism and a linear motor including a bolt member rotatable by an electric motor and a nut member screwed to the bolt member.

  The inclined illumination light source can be supported on the lifting platform such that the height position thereof is higher than the second polarizing plate. In addition, the inclined illumination light source can be supported on the lifting platform via a base for the backlight supported on the lifting platform on the lifting platform.

  The work table can be held at a distance from the lifting platform via a spacer member. In this case, the inclined illumination light source can be disposed in a space between the work table and the lifting platform defined by the spacer member.

  The frame of the work table can be adjusted in dimensions on each side of the opening so as to be suitable for liquid crystal panels having different sizes. Such a frame can be realized, for example, by combining the members in a cross-beam shape so that they can be translated.

  Instead of using the adjustable frame described above, the work table is removably supported on the lifting platform so that the work table provided with the opening suitable for the liquid crystal panel can be replaced. be able to.

  In the case of adopting a structure that can be replaced with a work table in which the opening can be adjusted according to the size of the liquid crystal panel as described above or a work table provided with the opening suitable for the liquid crystal panel, the reflecting means is used. The above-mentioned configuration is supported in which the reflecting means is held at an appropriate angle by the operating means for rotating the shaft around the shaft supported by the work table and rotating the shaft around the shaft. Is desirable. This is because, regardless of the size of the liquid crystal panel, the liquid crystal panel can be uniformly irradiated with oblique irradiation light in an appropriate incident angle range.

  According to the present invention, as described above, since the liquid crystal panel can be performed on a single apparatus without being transferred between two inspection sections, the inspection apparatus can be made compact and the tact time can be shortened. Can be achieved. Furthermore, since the non-lighting inspection under the tilted illumination light source enables the bright spot to be determined quickly and easily, the tact time can be further shortened.

It is sectional drawing which shows schematically the liquid crystal panel test | inspection apparatus which concerns on this invention. It is sectional drawing which shows the liquid crystal panel test | inspection apparatus in the non-lighting (non-drive) test | inspection step under backlight light source light. It is sectional drawing which shows the liquid crystal panel test | inspection apparatus in the non-lighting (non-drive) test | inspection step under inclination illumination light source light. It is sectional drawing which shows the liquid crystal panel test | inspection apparatus in the lighting (driving) test | inspection step under backlight light source light. The imaging screen obtained by the imaging device in each inspection step is shown, (a) is the imaging screen obtained in the non-lighting (non-driving) inspection step under the backlight light source light shown in FIG. 2, (b) 4 is an imaging screen obtained in the non-lighting (non-driving) inspection step under the inclined illumination light source light shown in FIG. 3, and (c) is the lighting (driving) inspection step under the backlight light source light shown in FIG. It is the obtained imaging screen. It is sectional drawing similar to FIG. 3 which shows the other example of the liquid crystal panel test | inspection apparatus which concerns on this invention. It is sectional drawing which shows the conventional liquid crystal panel test | inspection apparatus.

  The liquid crystal panel inspection apparatus 10 according to the present invention is used for inspection of a liquid crystal panel 12 that does not have a pair of polarizing plates. The liquid crystal panel 12 has a rectangular planar shape, and a well-known electrode (not shown) for applying a driving voltage to each pixel of the liquid crystal panel 12 is provided on each side portion of one surface (upper surface) 12a. Are arranged.

  The liquid crystal panel inspection apparatus 10 includes a lift 14 that can be lifted and lowered along a vertical direction (z-axis direction) as viewed in FIG. 1, and a liquid crystal panel 12 that is supported on the lift and is an object to be inspected. And an imaging means 18 such as a CCD camera capable of photographing the upper surface 12a of the liquid crystal panel 12 held on the work table from above the work table 16.

  The lifting platform 14 can be constituted by, for example, an xyzθ stage that can move in the x and y directions on the xy plane perpendicular to the z axis and that can rotate about the z axis. On the lift 14, a well-known backlight unit 20 is arranged so as to be located almost directly below the liquid crystal panel 12 held on the work table 16. The backlight unit 20 is attached to the lifting platform 14 by a unit base 20b so that the light emitting surface 20a thereof is substantially parallel to the lower surface 12b of the liquid crystal panel 12 held on the work table 16.

  Between the image pickup means 18 and the backlight unit 20, first and second polarizing plates 22 a and 22 b are disposed so as to be positioned above and below the liquid crystal panel 12, respectively. In the illustrated example, three cameras 18a, 18a, 18a are used as the imaging means 18, and the cameras 18a are arranged in alignment so as to slightly overlap the imaging regions. In addition, three first polarizing plates 22a are arranged corresponding to each camera 18a. Instead, the imaging region of each camera 18a can be covered with a single first polarizing plate 22a.

  The second polarizing plate 22b is disposed on the light emitting surface 20a of the backlight unit 20 via a light diffusing plate 24 for equalizing the light intensity. The first polarizing plate 22a and the second polarizing plate 22b are held so that their polarization directions are parallel to each other.

  The work table 16 that holds the liquid crystal panel 12 is held on the lift table 14 via the spacers 26 at intervals from the lift table and is disposed along each side of the rectangular liquid crystal panel 12. A rectangular frame body 28 is provided on the whole. The frame body 28 has a rectangular opening 28 a, and each side portion of the frame body 28 receives each corresponding side portion of the liquid crystal panel 12. Light from the backlight unit 20 that has passed through the light diffusion plate 24 and the second polarizing plate 22b can irradiate the lower surface 12b of the liquid crystal panel 12 through the opening 28a of the work table 16 at an angle substantially perpendicular to the surface. It is.

  For example, four linear inclined illumination light sources 32 are arranged in the space 30 held between the work table 16 and the lift 14 by the spacer 26. FIG. 1 shows two of the four inclined illumination light sources 32 facing each other. Each inclined illumination light source 32 extends substantially parallel to each corresponding side of the liquid crystal panel 12 and is disposed so as to surround the light emitting surface 20a of the backlight unit 20 in cooperation with each other. Further, each inclined illumination light source 32 is held on the unit base 20b of the backlight unit 20 by the bracket 32a so as to be held at a height position higher than the second polarizing plate 22b below the outer region of the liquid crystal panel 12. It is supported by. Instead of supporting the inclined illumination light source 32 on the unit base 20b, it can be directly supported on the lifting platform 14.

  On the inner side of the work table 16, that is, on the side of the opening 28 a of the frame 28, a reflecting means 34 such as a reflecting mirror along the corresponding side portion of the frame 28 has its reflecting surface 34 a at the center of the opening 28 a. It is arranged toward the. Each reflecting means 34 is rotatably supported on the work table 16 at the upper edge by a shaft 36 that is disposed substantially horizontally and supported by the work table 16. Further, the work table 16 is provided with an actuating device 38 for rotating each reflecting means 34 around the shaft 36.

  Each actuating device 38 is operatively connected to the lower edge of the corresponding reflecting means 34 in order to adjust the rising angle θ of the reflecting means 34, which is a narrow angle between the reflecting surface 34a and the horizontal surface, and to maintain the desired setting angle. Has been. As such an actuating means 38, for example, although not shown, a conventionally well-known ball screw mechanism or linear that includes an electric motor, a bolt member that can be rotated by the electric motor, and a nut member that is screwed to the bolt member. A motor or the like can be employed.

  The actuating device 38 sets each rising angle θ to be less than 90 degrees, so that, as will be described later, the reflecting means 34 disposed on one of the corresponding sides of the opening 28a is along the other side facing each other. The oblique illumination light from the arranged inclined illumination light source 32 is guided to the lower surface 12b so that the incident angle to the lower surface 12b of the liquid crystal panel 12 is appropriate.

  In the example shown in FIG. 1, in order to make it possible to replace the work table 16 having the opening 28a corresponding to the size of the liquid crystal panel 12, the work table 16 is not shown, but a bolt-nut assembly or a releasable clamp mechanism or the like. Is removably coupled to the spacer 26.

  In FIG. 1, a work table 16 having an opening 28a of a size suitable for the liquid crystal panel 12 shown by a solid line is shown by a solid line, and the work table 16 having a size smaller than that is suitable for a liquid crystal panel 12 '. A work table 16 'having an opening 28a' is shown in phantom.

  Instead of replacing the entire work table 16 with the work table 16 'as described above according to the dimensions of the liquid crystal panel 12, four side members are provided as disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-163426. The frame body 28 having the opening 28a whose dimensions can be adjusted can be configured by coupling in a cross-beam shape or a hook shape so as to be able to move in parallel.

  Above the work table 16, a well-known probe unit 40 for driving the liquid crystal panel for lighting inspection of the liquid crystal panel 12 on the work table is disposed. The probe unit 40 brings the corresponding probe 40 a into contact with the electrode of the liquid crystal panel 12 at the raised position of the lifting platform 14.

  The imaging means 18 is set so that the distance from the liquid crystal panel 12 is constant when the liquid crystal panel 12 is inspected. Image data obtained by each imaging means 18 is sent to a well-known image processing device 42.

  Hereinafter, a procedure for inspecting the liquid crystal panel 12 using the liquid crystal panel inspection apparatus 10 will be described.

[Non-lighting inspection under backlight illumination]
In the non-lighting inspection under the backlight irradiation light, the inclined illumination light source 32 is turned off, and the backlight unit 20, that is, the backlight light source is turned on. Further, as shown in FIG. 2, each probe 40a of the probe unit 40 is in a non-contact state with the electrode of the liquid crystal panel 12, so that the liquid crystal panel 12 is in a non-lighting (non-driving) state. I'm left.

  In this non-lighting state, the light emitted from the light emitting surface 20a of the backlight unit 20 passes through the second polarizing plate 22b while being suitably dispersed by the light diffusion plate 24. The light from the backlight unit 20 is converted into polarized light by passing through the second polarizing plate 22b, and the polarized light is incident on the liquid crystal panel 12 at a substantially right angle. Since the liquid crystal panel 12 is in a non-driven state, the polarization plane of the polarized light is rotated 90 degrees by the transmission of the liquid crystal panel 12. The polarized light whose plane of polarization has been rotated by 90 degrees is blocked from being transmitted by the first polarizing plate 22a.

  As a result, the polarized light is not captured by each camera 18a, and the image of the liquid crystal panel 12 that has passed through the first polarizing plate 22a has no foreign matter attached to the upper surface 12a or the lower surface 12b of the liquid crystal panel 12, and the liquid crystal panel. As long as there are no defects in the 12 pixels, the shooting screen of the liquid crystal panel 12 obtained by shooting with each camera 18a and processing the data with the image processing device 42 is observed as a black screen. However, if foreign matter adheres to the upper surface 12a or the lower surface 12b of the liquid crystal panel 12 or foreign matter is present inside the pixels of the liquid crystal panel 12, these cause scattering of the polarized light, and the scattered light is imaged through the first polarizing plate 22a. The means 18 is regarded as a bright spot.

  The polarized light obtained by the light from the backlight unit 20 passing through the light diffusing plate 24 and the second polarizing plate 22b is substantially liquid crystal by the reflecting surface 34a held at the rising angle of the angle θ approximating a right angle. It is not directed to the periphery of the panel 12.

  FIG. 5A shows an example of bright spots scattered on the black screen obtained from the image processing device 42. In the example shown in FIG. 5A, four bright spots 44a, 44b, 44c, and 44d are observed.

  Of these four bright spots 44a, 44b, 44c, and 44d, which of the four bright spots 44a, 44b, 44c, and 44d is caused by foreign matter adhering to the upper surface 12a and the lower surface 12b of the liquid crystal panel 12 that is not defective, and the pixels of the liquid crystal panel 12 that can be regarded as pixel defects It is necessary to determine whether it is due to internal foreign matter. In order to determine the bright spot due to the adhesion of the foreign matter and the bright spot due to the pixel defect, a non-lighting inspection under inclined illumination light source light described below is performed.

[Non-lighting inspection under tilted illumination source light]
In the non-lighting inspection under the inclined illumination light source, the inclined illumination light source 32 is turned on instead of the backlight unit 20, and the backlight unit 20 is turned off. Further, as shown in FIG. 3, each probe 40a of the probe unit 40 is in a non-contact state with the electrode of the liquid crystal panel 12, so that the liquid crystal panel 12 is in a non-lighting (non-driving) state. I'm left.

  Light from the inclined irradiation light source 32 is irradiated obliquely upward toward the lower surface 12b of the liquid crystal panel 12 on the work table 16 without passing through the light diffusion plate 24 and the second polarizing plate 22b. Although the inclined illumination light source 32 is arranged along each side of the liquid crystal panel 12, light from the inclined illumination light source sufficiently reaches the vicinity of the corresponding side of the liquid crystal panel 12 to which the inclined illumination light source is adjacent. It is difficult to do. For example, the oblique light emitted from the inclined irradiation light source 32 located on the right side in the drawing as viewed in FIG. 3 does not easily reach the peripheral portion of the liquid crystal panel 12 located on the right side in the drawing. Similarly, the oblique light emitted from the inclined irradiation light source 32 located on the left side in the figure does not directly reach the peripheral part of the liquid crystal panel 12 located on the left side in the figure.

  However, the liquid crystal panel inspection apparatus 10 according to the present invention is provided with the reflecting means 34 that is rotatably supported on the work table 16 by the shaft 36 and whose rising angle θ is adjusted to an appropriate angle by the operating device 38. Therefore, for example, part of the oblique light emitted from the inclined irradiation light source 32 provided on the right side of FIG. 3 is reflected on the liquid crystal panel by the reflecting surface 34a of the reflecting means 34 provided on the left side of FIG. 12 is guided at an incident angle of α degrees toward the peripheral portion located on the right side of the lower surface 12b of the figure. Similarly, a part of the oblique light emitted from the inclined irradiation light source 32 provided on the left side of FIG. 3 is reflected on the lower surface of the liquid crystal panel 12 by the reflection surface 34a of the reflection means 34 provided on the right side on the opposite side. It is guided at an incident angle of α degrees toward the peripheral portion located on the left side of the figure of 12b.

  The amount of light at each peripheral portion of the liquid crystal panel 12 is increased by the reflected light from the reflecting surface 34a of the reflecting means 34, so that the shortage of light at the peripheral portion is eliminated. The above-described rising angle θ of the reflection means 34 can be adjusted to an appropriate angle of less than 90 degrees so that the incident angle α to the reflection surface 34a is 60 degrees or more and less than 90 degrees.

  The oblique irradiation light from the inclined irradiation light source 32 does not reach the imaging means 18 via the first polarizing plate 22a unless it is scattered. However, if foreign matter adheres to the upper or lower surfaces 12a and 12b of the liquid crystal panel 12, a part of the scattered light of the foreign matter is captured by the imaging means 18 through the first polarizing plate 22a. In addition, even a defect in the liquid crystal panel 12 is scattered, but not as strongly scattered as the foreign matter. As a result, in the black screen of the surface 1a of the liquid crystal panel 1 photographed by the imaging means 18 through the first polarizing plate 22a under the oblique illumination light of the oblique illumination light source 32, as shown in FIG. In addition, four bright spots 44a, 44b, 44c, and 44d are observed at the same positions as shown in FIG. However, since there is a clear luminance difference between the bright spot due to the foreign matter and the bright spot due to the defect, the image processing device 42 sets the appropriate threshold value in the image processing device, so that the brightness thereof Based on the difference, a bright spot caused by a foreign substance and a bright spot caused by a pixel defect are discriminated. In the illustrated example, the bright spots 44b, 44c, and 44d are caused by a foreign substance, and the bright spot 44a having a lower luminance than the bright spots 44b, 44c, and 44d is caused by a pixel defect. Therefore, it can be determined that the bright spot 44a is a pixel defect to be detected.

  As described above, the oblique irradiation light from the inclined irradiation light source 32 is spread over the entire area of the liquid crystal panel 12 with a desired light amount because the reflection means 34 compensates for the light amount shortage in the peripheral portion of the liquid crystal panel 12. . Therefore, even if the bright spot due to the foreign matter and the bright spot due to the pixel defect are located in the peripheral portion of the liquid crystal panel 12, it is possible to discriminate both relatively easily and reliably based on the luminance difference.

[Lighting inspection]
Subsequently, the liquid crystal panel 12 on the work table 16 undergoes a lighting test in a state where each pixel is driven. In this lighting inspection, as shown in FIG. 4, each probe 40 a of the probe unit 40 contacts the corresponding electrode of the liquid crystal panel 12 on the work table 16, and a drive voltage is supplied to each pixel. . Therefore, each pixel of the liquid crystal panel 12 does not rotate the polarization plane of the light passing therethrough. Therefore, when the backlight unit 20 is turned on again in place of the inclined irradiation light source 32, the light from the backlight unit 20 is converted into uniform polarized light through the light diffusion plate 24 and the second polarizing plate 22b. Since this liquid crystal panel 12 is in a driving state, this polarized light is transmitted through the liquid crystal panel 12 without rotating its polarization plane and reaches the first polarizing plate 22a. The first polarizing plate 22a allows transmission of the polarized light whose polarization plane is not rotated. As a result, the image of the liquid crystal panel 12 obtained by the imaging means 18 is a white screen when the liquid crystal panel 12 is a monochrome panel, that is, a color screen according to the color scheme of the filter when the liquid crystal panel 12 is a color panel.

  In this lighting screen, as shown in FIG. 5C, the pixel defects and the foreign matters described above are captured as black dots 44a, 44b, 44c, and 44d, respectively, and each pixel is displayed on the lighting screen. A partitioning black matrix 46 is captured. From the black image or the image data obtained in FIGS. 5A and 5B, it is determined that the bright spot 44a is caused by a pixel defect, and the black spot 44a on the lighting screen corresponding to this bright spot 44a. The pixel address can be easily obtained from the image of FIG. 5C in which the black matrix 46 is reflected or its image data. Therefore, it is possible to easily obtain the pixel address of the black point 44a in FIG.

  According to the liquid crystal panel inspection apparatus 10 according to the present invention, as described above, all the inspection steps of the liquid crystal panel 12 can be performed on the single work table 16 of the single liquid crystal panel inspection apparatus 10. The apparatus can be made compact, and the tact time can be shortened. Further, in the non-lighting inspection under oblique light of the inclined illumination light source 32, sufficient irradiation light can be guided to the peripheral part of the liquid crystal panel 12 by the reflecting means 34, so that the liquid crystal panel is also provided in the peripheral part of the liquid crystal panel 12. Since it is possible to quickly and easily determine the bright spot due to the foreign matter adhering to the 12 faces 12a and 12b and the bright spot due to the pixel defect, the tact time can be further shortened.

  FIG. 6 shows a work table having an opening 28a ′ having a size suitable for the liquid crystal panel 12 ′ having a smaller size than the liquid crystal panel 12 shown by a solid line in FIG. 1, as indicated by a virtual line in FIG. It is drawing which shows the example using 16 'and shows the non-lighting test | inspection under inclination illumination light source light similar to FIG.

  As shown in FIG. 6, when the small liquid crystal panel 12 ′ is handled as compared with the case where the large liquid crystal panel 12 is handled, the rising angle θ of the reflecting means 34 is set to a smaller value than in the former case. . The rising angle θ of the reflecting means 34 ensures a sufficient amount of light in the peripheral portion of the liquid crystal panel 12 ′ by operating the operating device 38 ′ of the work table 16 ′ as in the case of the large liquid crystal panel 12 described above. Therefore, the incident angle α to the lower surface 12b ′ of the liquid crystal panel 12 ′ is set to an angle within an appropriate angle range (60 degrees or more and less than 90 degrees).

  The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the rising angle θ of the reflecting means can be fixed. Moreover, a single camera can be used as the imaging means 18, and the number of cameras can be increased according to the required image resolution.

DESCRIPTION OF SYMBOLS 10 Liquid crystal panel inspection apparatus 12, 12 'Liquid crystal panel 12a, 12a' Upper surface of liquid crystal panel 12b, 12b 'Lower surface of liquid crystal panel 14 Lifting table 16, 16' Work table 18 Imaging means 20 Backlight unit 22a, 22b Polarizing plate 26 Spacer 28 Frame body 32 Inclined irradiation light source 34 Reflecting means 34a Reflecting surface 36 Axis 38 Actuator 40 Probe unit

Claims (10)

A liquid crystal panel inspection apparatus for inspecting a liquid crystal panel without a polarizing plate,
A platform,
A work table disposed on the lifting platform, comprising a frame having a rectangular opening as a whole, and receiving the edge of the liquid crystal panel by the frame to hold the liquid crystal panel above the lifting platform A work table,
First and second polarizing plates disposed above and below the liquid crystal panel on the work table, the polarization directions of which are maintained in a predetermined relationship with each other;
A backlight unit that irradiates the liquid crystal panel on the work table with irradiation light substantially perpendicular to the lower surface from the lower surface of the liquid crystal panel through the second polarizing plate;
An inclined illumination light source for angularly illuminating the liquid crystal panel on the work table from below the lower surface;
A probe unit for applying a voltage to the pixels of the liquid crystal panel for lighting inspection of the liquid crystal panel at the raised position of the elevator;
For photographing the upper surface of the liquid crystal panel through the first polarizing plate while selectively receiving either the right-angle irradiation light from the backlight unit or the oblique irradiation light from the inclined illumination light source An imaging device;
A part of the oblique irradiation light is arranged in the work table so that the oblique irradiation light from the inclined illumination light source enters the liquid crystal panel at an appropriate incident angle without passing through the second polarizing plate. A liquid crystal panel inspection apparatus including a reflecting means for guiding the peripheral portion of the lower surface of the liquid crystal panel.   The reflecting means is supported so as to be rotatable about an axis supported by the work table so as to enable uniform oblique irradiation to the lower surface of the liquid crystal panel according to the size of the liquid crystal panel. The liquid crystal panel inspection apparatus according to claim 1, wherein the reflecting means is held at an appropriate angle by an operating means for rotating about the axis.   The angle of the reflecting means is adjusted by the actuating device so that an incident angle to the lower surface that is reflected by the reflecting means and enters the liquid crystal panel is set to 60 degrees or more and less than 90 degrees. The liquid crystal panel inspection apparatus described in 1.   The axis of the reflecting means is disposed along one side of a pair of opposite sides of the rectangular opening of the work table, and the inclined illumination light source extends along the other side of the pair of sides. The liquid crystal panel inspection apparatus according to claim 2, wherein the liquid crystal panel inspection apparatus is arranged appropriately.   The reflecting means comprises a reflecting mirror supported on the work table via a horizontal axis at the upper edge, and the actuating device is operatively applied to the reflecting mirror to hold the reflecting mirror at a desired rising angle. The liquid crystal panel inspection apparatus according to claim 4, wherein the liquid crystal panel inspection apparatus is combined.   The liquid crystal panel inspection apparatus according to claim 5, wherein the operating device includes a ball screw mechanism or a linear motor including a bolt member rotatable by an electric motor and a nut member screwed to the bolt member.   2. The liquid crystal panel inspection apparatus according to claim 1, wherein the inclined illumination light source is supported by the lifting platform so that a height position thereof is higher than that of the second polarizing plate.   The work table is held at a distance from the lift table via a spacer member, and the inclined illumination light source is disposed in a space between the work table and the lift table defined by the spacer member. The liquid crystal panel inspection apparatus according to claim 7.   The liquid crystal panel inspection apparatus according to claim 1, wherein a dimension of each side of the opening is adjustable so that the frame of the work table is suitable for liquid crystal panels having different sizes.   The liquid crystal panel inspection apparatus according to claim 1, wherein the work table is removably supported on the lifting platform so that the work table can be replaced with a work table provided with the opening suitable for the liquid crystal panel. .

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