JPH08166779A - Defect inspection apparatus and defect inspection method - Google Patents

Abstract

PURPOSE: To avert erroneous decision at the time of inspection by projecting and displaying the light image obtd. by illuminating a transmissible object to be inspected on a screen and inspecting the defect of the object to be inspected by visually observing this displayed image. CONSTITUTION: A liquid crystal panel 10 to be inspected is set in the prescribed position on a stage 19. This liquid crystal panel 10 is then connected to a panel driving section 11 and is driven. In succession, a light source 2 is lighted to illuminate the liquid crystal panel 10 and the light image of the display screen is projected via a projecting lens system 14 and first and second mirrors 15, 16 onto a screen 17. At this time, an operator (inspector) 18 changes a projection magnification by operating an operation panel 12 and visually inspects the defect with the display screen of the liquid crystal panel 10 projected on the screen 17. Continuous execution of such operation is possible as well. The video of the display screen of the liquid crystal panel 10 is exactly projectable on the screen 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection apparatus and a defect inspection method used in an inspection process of a liquid crystal display device such as a liquid crystal panel.

[0002]

2. Description of the Related Art Conventionally, as one of the methods for inspecting a defect of a liquid crystal display device after assembly, a display screen of the liquid crystal display device is driven and its optical image is a solid-state image pickup device such as CCD (charge coupled device). A method is known in which the captured image is captured on the screen of a cathode ray tube and the image is visually inspected.

FIG. 4 shows an example of such a method and an apparatus for implementing it. That is, FIG.
In the conventional method, the liquid crystal panel 52 to be inspected is connected to the drive board 53, as shown in FIG.
The two polarizing plates 54 and 55 are placed so as to sandwich the stage 51 and the liquid crystal panel 52. further,
A backlight 56 arranged below the polarizing plate 55 is turned on to irradiate the liquid crystal panel 52 with light, and an optical image on the display screen is captured by a television camera 57 having a solid-state image sensor 59 such as a CCD. The image is enlarged and displayed on the display device 58. Then, the defect on the liquid crystal panel 52 is visually identified based on the displayed image.

[0004]

However, in such a defect inspection apparatus, since the image is captured by the solid-state image pickup device 59, there is a problem that the accuracy of defect detection depends on the state of the solid-state image pickup device 59 and the like. is there. For example, if the solid-state image sensor 59 has a defect such as a white spot, the display image on the liquid crystal panel 52 cannot be accurately reproduced, and the determination may be erroneous. Further, since the television camera 57 captures the optical image of the liquid crystal panel 52 through the lens, a false signal (for example, moire fringes) due to the pixel pitch of the solid-state image sensor 59 and the liquid crystal panel 52 is generated, As a result, there is a problem that an erroneous determination is made during the image quality inspection.

The present invention has been made in consideration of the above problems of the prior art, and provides a defect inspection apparatus and a defect inspection method for accurately displaying an image of an inspection object to prevent erroneous determination. The purpose is to provide.

[0006]

A defect inspection apparatus according to the present invention guides a light source for illuminating a transparent inspection object and an optical image obtained by passing through the inspection object onto a screen. And an imaging optical system for

The image forming optical system has a telecentric lens system.

Further, the image forming optical system is configured to project an optical image obtained by passing through the object to be inspected onto the front surface of the screen.

On the other hand, in the defect inspection method according to the present invention, an optical image obtained by illuminating a transparent inspection object is projected and displayed on a screen, and the displayed image is visually observed to detect defects in the inspection object. It is configured to inspect.

[0010]

In the defect inspection apparatus according to the present invention, since the solid-state image sensor such as CCD is not used, white spots, moire fringes and the like due to the state of the solid-state image sensor do not appear on the screen. , An object to be inspected, in particular, an image on the display screen of the liquid crystal display device 10 in a driven state is accurately displayed on the screen 1.
It can be projected on 7. As a result, it is possible to avoid erroneous determination during the image quality inspection.

In this case, by using an image-forming optical system having a telecentric lens system, for example, in a state close to a state in which a liquid crystal display device as an object to be inspected is actually incorporated in a projection optical device such as a projector. An inspection can be done.

Further, if the light image obtained by passing through the object to be inspected is projected on the front surface of the screen by the image forming optical system, it is possible to prevent the reduction of the luminance when the screen is transmitted in the rear projection type. it can.

On the other hand, in the case of the defect inspection method according to the present invention,
Since the light image obtained by illuminating the transparent inspection object is projected and displayed on the screen, the inspection is performed in a state close to that of directly inspecting the inspection object. A liquid crystal display device of a mold or a liquid crystal display device used for a device such as a projector for projection can be inspected in a state close to an actual use state.

[0014]

Embodiments of a defect inspection apparatus and a defect inspection method according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic block diagram showing an embodiment of the defect inspection apparatus according to the present invention. In the apparatus configuration shown in FIG. 1, a light source 2 including, for example, a metal halide lamp is provided below the apparatus body 1, and a reflecting mirror 3 is disposed on the back side of the light source 2. The positions of the light source 2 and the mirror 3 are adjusted so that the light source 2 emits light in the horizontal direction.

The direction of emission of light from the light source 2 and the light source 2
A mirror 4 for reflection is provided near the. The mirror 4 is fixed at an angle of 45 ° with respect to the horizontal direction so as to reflect the light from the light source 2 in the vertically upward direction.
Two rotatable turrets 5 and 6 are provided above the mirror 4. These turrets 5,
Reference numeral 6 denotes a plate-shaped member, and each plate-shaped member has a plurality of openings (not shown) formed therein. Although not shown, for example, an ND filter (Neut) for controlling the amount of light hitting the liquid crystal display device is provided in these openings.
Ral Density Filter) and R
Filters of respective colors such as (red), G (green), B (blue) are provided. Furthermore, above the turrets 5 and 6,
A plurality of condenser lenses 7 for condensing the light from the light source 2,
8 and 9 are arranged.

A stage 19 for setting an object to be inspected is provided above the condenser lens 9 and substantially in the center of the apparatus main body 1. A liquid crystal panel 10 as a liquid crystal display device, which is an object to be inspected, is placed on the stage 19. In this case, the liquid crystal panel 10 is placed so that the display screen to be inspected is located on the optical path of the light from the light source 2. The liquid crystal panel 10 is connected to a panel drive unit 11 for driving the liquid crystal panel 10, and is driven based on a control signal from an operation panel 12 provided on the front surface side of the apparatus body 1. A pair of polarizing plates (not shown) are arranged above and below the liquid crystal panel 10.

Further, above the liquid crystal panel 10, a projection lens system 14 attached to the rotary shaft 13 is arranged. The projection lens system 14 is composed of, for example, two single focus lenses, and constitutes a telecentric system optical system in combination with the above-mentioned condenser lenses 7, 8 and 9. In this case, a plurality of projection lens systems 14 having different magnifications are attached to the rotary shaft 13, and the projection magnification is switched by rotation of the rotary shaft 13 based on a control signal from the operation panel 12. By the way,
In this embodiment, for example, a projection lens system 14 having a projection magnification of 12 times and 20 times is attached to the rotary shaft 13. Further, in the case of this embodiment, the zoom mechanism is not intentionally adopted in the projection lens system 14 in order to suppress the aberration, but it goes without saying that the projection magnification can be arbitrarily changed by adopting the zoom mechanism.

Above the projection lens system 14, mirrors 15 and 16 for guiding the light from the light source 2 to the screen 17 are provided. More specifically, in this embodiment, one mirror 15 is arranged immediately above the projection lens system 14,
The other mirror 16 is arranged in the upper rear part of the apparatus main body 1. A screen 17 is arranged on the front side of the apparatus body 1.

When inspecting by using the above-described defect inspecting apparatus, first, the liquid crystal panel 10 to be inspected is set on the stage 1.
The liquid crystal panel 10 is connected to the panel drive unit 11 and driven. Then, the light source 2
Is turned on to illuminate the liquid crystal panel 10, and the optical image of the display screen is projected on the screen 17 through the above-mentioned projection lens system 14, the first and second mirrors 15 and 16. At this time, the operator (inspector) 18 operates the operation panel 12 to change the projection magnification, and visually inspects the display screen of the liquid crystal panel 10 projected on the screen 17 for defect inspection. Note that these operations can be performed continuously.

Thus, in the case of the apparatus of this embodiment, CC
Since a solid snow image element such as D is not used, white spots, moire fringes, etc. due to the state of the solid state image pickup element, etc.
The image on the display screen of the liquid crystal panel 10 can be accurately displayed on the screen 17 without appearing in the screen. Therefore, it becomes possible to perform the defect inspection with high accuracy in comparison with the conventional apparatus and method.

Further, according to the method of this embodiment, since the inspection is performed in a state close to that of directly looking at the liquid crystal panel 10, it is aimed at the projection of a direct view type liquid crystal display device such as a viewfinder or a projector. The liquid crystal display device can be inspected in a state close to the actual use state, and as a result, defect detection with higher accuracy can be performed.

The present invention is not limited to the above-mentioned embodiment, and various modifications can be made. For example,
The defect inspection apparatus according to the present invention is not limited to the rear projection type which projects an optical image from the liquid crystal panel 10 on the back surface of the screen 17 as shown in FIG.
It can also be applied to a front type inspection device that projects on the front surface of the. An example thereof will be described below.

FIG. 2 is a schematic configuration diagram showing a preferred example of the defect inspection apparatus when applied to the front type. In the device configuration shown in FIG. 2, a light source 22 including, for example, a metal halide lamp is provided below the device body 21.
Further, a cooling fan 23 is attached near the light source 2. A fixed filter 24 is arranged above the light source 22 on its optical path. This fixed filter 24
In order to avoid the adverse effect of heat on the inspection accuracy, the light source 22
It is provided to cut out the infrared region, which particularly has a heating effect, from the light components emitted from, and a cooling fan 25 is provided in the vicinity thereof to prevent overheating of the filter. There is. The fixed filter 24
Can be similarly provided in the inspection apparatus shown in FIG.

Above the fixed filter 24, a flat plate-shaped 2
The turrets 26 and 27 are arranged with a predetermined gap, and the individual turrets 26 and 27 are mounted on the same rotary shaft 28 in parallel with each other. A plurality of openings are formed in each of the turrets 26 and 27 as in the above embodiment, and an ND filter or a filter of each color (red, green, blue) is set in each opening. Further, above the turrets 26 and 27, a condenser lens system 2 for condensing the light emitted from the light source 22.
9 are arranged.

Above the condenser lens system 29, the apparatus main body 21 is provided.
A stage 30 for setting an object to be inspected is provided at a substantially central position. And this stage 1
A liquid crystal panel 31 as a liquid crystal display device, which is an object to be inspected, is mounted on the display panel 9. In this case, the liquid crystal panel 3
As described in the above embodiment, 1 is placed so that the display screen to be inspected is located on the optical path emitted from the light source 22. The liquid crystal panel 31 is connected to a panel drive unit 32 for driving the liquid crystal panel 31, and is driven based on a control signal from an operation panel (not shown) provided on the front surface side of the apparatus body 21. In this embodiment also, a pair of polarizing plates (not shown) are arranged above and below the liquid crystal panel 31.

On the other hand, above the liquid crystal panel 31, a turret 34 is arranged so as to be supported by the rotating shaft 33. In the opening (not shown) of this turret 34,
For example, an ND filter for controlling the amount of light that has passed through the liquid crystal panel 31 and color filters that transmit only specific color components are set. Further, a projection lens 35 is arranged above the turret 34. By the way, in this embodiment, a fixed single focus lens is adopted to suppress the aberration, but as the projection lens system, a lens system capable of switching magnification as in the above embodiment and a lens system having a zoom mechanism are used. It can also be adopted.

Above the projection lens 35, a mirror 3 for reflecting the optical image obtained by passing through the liquid crystal panel 31 by the illumination from the light source 22 toward the front surface of the screen 36.
7 are arranged. The mirror 37 is attached at an angle of 45 ° so as to horizontally reflect an image of light emitted from the light source 22 in the vertical direction. Also, mirror 3
The light image reflected by 7 is projected perpendicularly to the front surface of the screen 36 in order to prevent distortion of the display screen displayed on the front surface of the screen 36.

A half mirror (first mirror) 38 is arranged on the optical path between the mirror 37 and the screen 36, and a mirror (second mirror) 39 is arranged above the half mirror 38. . The half mirror 38 is
The reflected light image from the front surface of the screen 36 (the liquid crystal panel 3
1 display screen image) to reflect in the vertical direction,
The mirror 39 is arranged at an angle of 45 ° with respect to the screen 36, and the mirror 39 above it is parallel to the reflected light image reflected by the half mirror 38, that is, parallel to the axis of the light image projected on the screen 36. It is arranged at an angle of 45 ° in the same manner as the half mirror 38 in order to reflect the light.

When inspecting by using the above defect inspecting apparatus, first, the liquid crystal panel 31 to be inspected is moved to the stage 30.
The liquid crystal panel 31 is set to a predetermined position above, and then the liquid crystal panel 31 is connected to the panel drive unit 32 and driven. Then, the light source 22
Is turned on to illuminate the liquid crystal panel 31, and the optical image of the display screen is projected on the front surface of the screen 37 via the projection lens 35 and the mirror 37 described above. In addition, the screen 37
The reflected light image from the front surface (light image of the display screen of the liquid crystal panel 31) is emitted to the front surface side of the apparatus main body 21 via the half mirror 38 and the mirror 39. Therefore, the device body 2
The operator (inspector) 40 who is heading for 1 is the screen 3
The display screen of the liquid crystal panel 31 projected on the front of 6
It can be visually confirmed from the direction coaxial with the axis of the optical image traveling from the mirror 37 to the screen 36.

This makes it possible to avoid a decrease in the brightness of the rear projection type during screen transmission, so that it is possible to perform an inspection on a brighter screen screen, and it is expected that the inspection accuracy will be improved. Further, since it becomes possible to visually confirm from a direction which is pseudo coaxial with the axis of the optical image directed to the screen 36, the liquid crystal panel 31
It is possible to perform the inspection in the almost same state as when the display screen of 1 is viewed directly from the front. Further, since the light image reflected by the mirror 37 is projected vertically on the surface of the screen 36 so that the display screen of the liquid crystal panel 31 is projected on the front surface of the screen 36, erroneous determination due to screen distortion is surely performed. Can be prevented.

In the inspection apparatus according to the present invention,
The arrangement of the light source and the screen can be variously changed depending on how the mirror is reflected. For example, in the case of the front type, as shown in FIG. 3, an optical image obtained by passing through the liquid crystal panel 41 is projected on the front surface of the screen 44 via the projection lens 42 and the half mirror 43, It is also possible to emit the reflected light image to the front side of the device (left side in the drawing) via the half mirror 43 which is the first mirror, the mirror 45 which is the second mirror, and the mirror 46 arranged above it. On the operator side, it is possible to perform the inspection in substantially the same state as when the display image of the liquid crystal panel 41 is directly viewed from the front. Further, the object to be inspected is not limited to the liquid crystal display device such as the liquid crystal panel applied in the above-mentioned embodiment, but can be applied to various objects to be inspected as long as light can be transmitted. However, if it is applied to the liquid crystal display device as described above, the defect can be detected most effectively.

[0033]

As described above, according to the defect inspection apparatus of the present invention, since the solid-state image pickup device such as CCD is not used, white spots or moire on the screen due to the state of the solid-state image pickup device or the like. It is possible to prevent streaks and the like, and as a result, it is possible to accurately display the image of the inspection object, especially the display screen of the liquid crystal display device in the driven state. This makes it possible to reliably avoid erroneous determination in the image quality inspection and improve the accuracy and reliability of the defect inspection.

If a system having a telecentric lens system is used as the image forming optical system, for example, a state close to a state in which a liquid crystal display device as an object to be inspected is actually incorporated in a projection optical device such as a projector. Therefore, it is possible to manufacture an optimum liquid crystal display device according to various uses.

Further, if the optical image obtained by passing through the object to be inspected is projected on the front surface of the screen by the image forming optical system, it is possible to avoid a decrease in the luminance when transmitting through the screen in the rear projection type. Because you can
The inspection can be performed with a brighter display screen, and the inspection accuracy can be expected to improve.

In addition to this, according to the defect inspection method of the present invention, an optical image obtained by irradiating a transparent inspection object (for example, a liquid crystal display device in a driven state) is projected and displayed on the screen. Therefore, the visual inspection can be performed in a state close to that of directly looking at the inspection object. As a result, for example, a direct view type liquid crystal display device such as a viewfinder, or a liquid crystal display device used for a device for projection such as a projector, it is possible to perform an inspection in a state close to the actual use state, It is possible to further improve the accuracy of defect inspection.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a defect inspection apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram showing another embodiment of the defect inspection apparatus according to the present invention.

FIG. 3 is a schematic view of a main part showing a modified example of the present invention.

FIG. 4 is a schematic configuration diagram showing an example of a conventional defect inspection apparatus.

[Explanation of symbols]

 1 Device Main Body 2 Light Sources 7, 8, 9 Condensing Lens (Image Forming Optical System) 10 Liquid Crystal Panel (Liquid Crystal Display Device / Inspection Object) 11 Panel Drive Unit 14 Projection Lens System (Image Forming Optical System) 15 Mirror (Image Forming) Optical system 16 Mirror (imaging optical system) 17 Screen 18 Operator 36 Screen 38 Half mirror (first mirror) 39 Mirror (second mirror)

Claims (16)

[Claims] 1. A light source for illuminating a transparent inspection object, and an imaging optical system for guiding an optical image obtained by passing through the inspection object onto a screen. Defect inspection device. 2. The defect inspection apparatus according to claim 1, wherein the defect inspection apparatus is a liquid crystal display device in a state where an inspection object is driven. 3. The defect inspection apparatus according to claim 1, wherein the imaging optical system has a telecentric lens system. 4. The defect inspection apparatus according to claim 1, wherein the imaging optical system projects an optical image obtained by passing through the inspection object onto the front surface of the screen. 5. The defect inspection apparatus according to claim 2, wherein the imaging optical system has a telecentric lens system. 6. The defect inspection apparatus according to claim 2, wherein the imaging optical system projects an optical image obtained by passing through the inspection object on the front surface of the screen. 7. The defect inspection apparatus according to claim 3, wherein the imaging optical system projects an optical image obtained by passing through the inspection object on the front surface of the screen. 8. A first mirror for reflecting a reflected light image from the front surface of the screen in a predetermined direction, and the reflected light image reflected by the first mirror,
5. A second mirror for reflecting the light image projected on the front surface of the screen in parallel with the axis of the light image.
The described defect inspection device. 9. The defect inspection apparatus according to claim 5, wherein the imaging optical system projects an optical image obtained by passing through the inspection object on the front surface of the screen. 10. A first mirror for reflecting a reflected light image from the front surface of the screen in a predetermined direction, and the reflected light image reflected by the first mirror,
7. A second mirror for reflecting the light image projected on the front surface of the screen in parallel with the axis of the light image.
The described defect inspection device. 11. A first mirror for reflecting a reflected light image from a front surface of a screen in a predetermined direction, and the reflected light image reflected by the first mirror,
8. A second mirror for reflecting the light image projected on the front surface of the screen in parallel with the axis of the light image.
The described defect inspection device. 12. A first mirror for reflecting a reflected light image from the front surface of the screen in a predetermined direction, and the reflected light image reflected by the first mirror,
10. A second mirror for reflecting the light image projected on the front surface of the screen in parallel with the axis of the light image.
The described defect inspection device. 13. A defect characterized in that a light image obtained by illuminating a transparent inspection object is projected and displayed on a screen, and the displayed image is visually inspected for defects in the inspection object. Inspection methods. 14. The defect inspection method according to claim 13, wherein the liquid crystal display device is in a state in which a transparent inspection object is driven. 15. An optical image obtained by illuminating a transparent inspection object is projected and displayed on the front surface of a screen, and the displayed image is visually inspected for defects in the inspection object. The defect inspection method according to claim 13. 16. An optical image obtained by illuminating a transparent inspection object is projected and displayed on the front surface of the screen, and the displayed image is visually inspected for defects in the inspection object. The defect inspection method according to claim 14.