JPH06242410A - Lcd display body inspecting device - Google Patents

Abstract

PURPOSE:To provide an LCD display body inspecting device which facilitates the adjustment of the relative position relation between a camera, lighting, and a body to be inspected so that the reflection of incident light on the surface of the body to be inspected is evaded. CONSTITUTION:This inspecting device, is provided with a light source 5, the camera 3 which forms an optical image by passing measurement light 27 containing the incident light from an LCD display body 8 through a lens 2, and an image processor 6 which applies an inspection pattern to a liquid crystal display element in the LCD display body and is supplied with a photoelectric conversion output corresponding to the measurement light to collate it with the inspection pattern and then decides whether or not the LCD display body 8 has a defective. Further, this device has a polarizing filter plate 1 which is arranged over the entire surface of the lens 2 and can rotate. A driving control part 7 which drives and rotates the polarizing filter plate 1, and the image processor 6 further equipped with a contrast processing part which calculates how much the contrast of the optical image is spoiled from interference generated between reflected light and the measurement light and sends a control signal out to the driving control part 7 so that the contrast reaches a specific threshold value are provided.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an LCD (Liquid).
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal display (LCD) display inspection device, and more particularly, to an LCD display inspection device that suppresses the influence of interference light that interferes with an optical image from an LCD display that is an inspection object.

[0002]

2. Description of the Related Art A reflection type L which is a typical LCD display
As shown in the schematic view of FIG. 4, the CD display body 8 includes a TN type liquid crystal display element 21 and a drive line 20 for applying a drive voltage.
A reflection plate 24 for reflecting the light of an LED (not shown), which will be described later, so that the irradiation light is incident on the liquid crystal display element 21;
It is provided with polarizing plates 22 and 23 which have a polarization plane in the direction of the absorption axis (arrow) and which absorbs light, and a surface cover 25 which is a surface forming a part of the casing. Polarizers 22 and 23
When the absorption axes are arranged so as to be orthogonal to each other, the normally white mode is set, and when they are arranged so as to be parallel to each other, the normally black mode is set.

As a conventional example of a device for inspecting the liquid crystal display element 21 itself shown in FIG. 4, as shown in JP-A-61-178648 and JP-A-3-61993, the absorption axes are orthogonal to each other with respect to the polarizing plate 23. The two inspection polarizing plates are placed at the position of the polarizing plate 22 and slid to make the absorption axis relatively orthogonal to or parallel to the polarizing plate 23 to simulate the normally white mode and the normally black mode. There is known a device that can be realized in real time to inspect a white defect or a black defect. It is to be noted that an LCD display body is commercially available in which the polarizing plates 22.23 are attached to the front and back surfaces of the liquid crystal display element 21 after the above-mentioned absorption axes are aligned according to the desired mode. Further, the above-mentioned LED is arranged at an end portion between the reflection plate 24 and the polarizing plate 23, irradiates the reflection plate 24, and the reflected light is incident on the polarizing plate 23 at a substantially right angle. Instead of the reflection plate 24, there is also a system in which a backlight is arranged at this position for irradiation. Although the above-mentioned LCD display inspection apparatus can detect the presence or absence of defects in the liquid crystal display element itself in both modes, it occurs on the front and back of each of the two polarizing plates 22 and 23 and the front and back of the reflection plate 24. No consideration is given to the influence of interference caused by reflected light. On the other hand, as shown in FIG. 3, the conventional example of the LCD display body inspection apparatus for mass production is as follows.
A light source 5 for illuminating the LCD display body 8 and a camera 3 with a lens 2 using a CCD or the like for receiving the measurement light 27.
And the drive line 20 to the liquid crystal display element 21 of the LCD display body 8,
The applied voltage of a specific pattern for inspection (characters, all dots turned on, all turned off, checkered pattern turned on, etc.) is output via 20A, and the photoelectrically converted signal received by the camera 3 and the sending specific pattern are collated. In addition, the image processing apparatus 6A determines whether or not there is a defect in the display function. Next, the state of the measuring light in the operation of the conventional example will be described. Referring also to FIG. 4, the incident light 26 from the light source 5 has a surface cover 25,
The light enters the reflection plate 24 through the polarization plate 22, the liquid crystal display element 21, and the polarization plate 23, and is reflected by the reflection plate 24. The reflected light from the reflection plate 24 travels in the opposite path to the measurement light 2
It becomes 7. In the example of FIG. 4, only the light polarized in a specific direction by the normally white mode polarization plates 22 and 23 is output as the measurement light 27. The incident angle of the incident light 26 with respect to the display body 8 is set by selecting the relative positional relationship of the light source 5 with respect to the display body 8 so that the measurement light 27 is correctly incident on the lens 2.

However, the light reflected on the surface of the object to be measured is incident on the lens 2 due to the relative positional relationship between the camera 3, the light source 5 and the object to be inspected, causing interference with the desired measuring light, and the camera 3 deteriorates the sharpness of the optical image of the display body 8 formed inside 3. Particularly in the case of the object to be measured in which the surface cover 25 is installed in front of the LCD element 21 with a distance, the shadow of the opaque portion of the cover is the liquid crystal display element 21.
It is necessary to make the incident angle of the incident light large so as not to project the light on the surface of the camera 3. However, if this is done, there is a high possibility that the reflected light from the surface cover 25 will enter the camera 3 and cause the above-mentioned interference. The relative positional relationship with the DUT 8 requires delicate adjustment. In this case, the cover 2 of the DUT 8
If there is a variation in the mounting angle between the reflector 5 and the reflection plate 24, it is necessary to adjust the relative positional relationship for each object to be measured.

[0005]

As described above, in the conventional LCD display inspection apparatus, the reflection of the incident light on the surface of the inspection object enters the lens of the camera and interferes with the measurement light from the display section. Then, the sharpness, that is, the contrast, of the optical image on the display portion is deteriorated, which makes it difficult to perform image processing for determining the presence or absence of a defect in the inspection object. There is a drawback that adjustment is required to set the relative positional relationship among the camera, the illumination, and the inspection object so as to avoid the reflection.

[0006]

According to the present invention, a light source for supplying incident light to an LCD display body as an object to be inspected at a predetermined incident angle, and a measuring light including reflected light from the LCD display body as a lens. A camera that produces an optical image corresponding to the received measurement light via the lens and a drive voltage corresponding to the inspection pattern is generated.
An LCD having an image processing device which is applied to a liquid crystal display element in a CD display body and is supplied with a photoelectric conversion output corresponding to the measurement light and collated with the inspection pattern to determine whether or not there is a defect in the LCD display body. In the display body inspection apparatus, a polarization filter plate disposed in front of the lens and rotatable about the optical axis of the lens, a drive control unit that rotationally drives the polarization filter plate, and the reflected light between the measurement light. The image processing apparatus further comprising: a contrast processing unit that calculates the degree of the contrast of the optical image that is impaired by the interference caused by the above, and sends a control signal to the drive control unit so that the contrast reaches a predetermined threshold value. Have and.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

Referring to FIG. 1, which is a perspective view of an embodiment of the present invention, in this embodiment, a support member 8A for supporting an LCD display body 8 as an object to be inspected and an inspection pattern from an image processing apparatus described later are provided. Drive lines 20A, 20 for transmitting the drive signal of
And a camera 3 for forming an optical image of the LCD display body 8 by measuring light, and a condenser lens 2 attached to the camera 3.
The circular polarization filter plate 1 attached to the light receiving surface of the lens 2 and rotatable about the optical axis of the lens 2, the rotation drive unit 4 for rotating the polarization filter plate 1, and the illumination light to the inspection object 8. It comprises a light source 5 to be supplied, an image processing device 6 connected to the camera 3, a rotation drive unit 4 and a controller 7 which generates a drive voltage under the control of the image processing device 6. When the inspection object 8 is irradiated with the incident light 26 from the light source 5 and the camera 3 forms an optical image of the inspection object 8 by the measurement light to the lens 2, the controller 7 controls the rotation driving unit 4 to polarize the light. While rotating the filter plate 1,
The image signal a from the camera 3 is processed by the image processing device 6. The polarizing filter plate 1 has the same characteristics as the polarizing plate 22 in the LCD display body 8 and transmits only the polarized component in the direction perpendicular to the absorption axis. Therefore, in principle, at the point where the polarization axes of the polarization plate 22 and the polarization filter 1 coincide with the rotation of the polarization filter plate 1, the amount of transmitted measurement light 27 becomes maximum. Here, even if the incident light on the lens 2 of the reflected light from the surface cover 25, the polarizing plate 22 or the like, that is, the reflected light generated in a random direction with respect to the plane of the display 8 coincides with the measurement light, the change axis thereof is changed. Since they do not match, they can be removed by the polarizing filter plate 1. The contrast is high at the rotation angle of the polarization filter plate 1 where the change in the amount of the measurement light caused by the ON / OFF switching of the drive signal is the largest.

The method for setting the rotation angle of the filter plate 1 for maximizing the contrast is performed by the processing procedure of the contrast processing unit added to the image processing apparatus 6 according to the present invention, and the controller 7 is controlled. The rotation drive unit 4 is driven.

The processing procedure of this contrast processing section is shown in FIG.
The flowchart will be described. First, the liquid crystal display element (LCD) is brought into a non-driving state so that only the reflected light L2 is incident on the lens 2 (step S1). Next, rotation of the polarization filter plate 1 is started (S2). The light quantity level of the reflected light L2 is sequentially measured and stored for each pitch Δθ of this rotation angle (S3). The pitch of this rotation angle is determined in consideration of the resolutions of the reflected light and the measurement light that cause interference. After the polarizing filter plate 1 is rotated 360 degrees, the LCD is switched to the driving state (S4). At this stage, both the reflected light and the measuring light that has passed through the LCD element 21, the polarizing plates 22 and 23 and the reflector 24 are reflected by the lens 2.
It becomes incident light on. This incident light is measured and stored as the reflected light level L1 for each rotation angle pitch Δθ (S5).
Next, the maximum value L1M of the reflected light level L1 and the corresponding rotation angle θ1 are extracted (S6). Since the ratio of the maximum value L1M to the reflected light level L2 at the rotation angle θ1 represents the L1M / L2 contrast, the value of this ratio is calculated (S7). It is compared whether or not this ratio L1M / L2 exceeds a threshold value T required for determining the inspection pattern in the image processing device 6 (S8). If the result of this comparison is YES, the image processing device 6 sends the original inspection pattern (for example, a checkerboard pattern), and the LCD
Whether or not there is a defect in the display body 8 is determined (S9). If the comparison result is NO, the position of the light source 5 is adjusted (S1
0), steps 1 to 8 are repeated. If the contrast satisfies the predetermined threshold value T by the procedure of the contrast processing section, the relative positional relationship between the light source 5 and the camera 3 including the lens 2 is set, and the LCD display of the next object to be inspected is set. Even if the position of the body 8 is slightly displaced and the polarization axis of the measurement light 27 is changed, the contrast is not significantly deteriorated. As is clear from the above description, the local defect inspection of the LCD display element 21 is possible by limiting the range of the surface of the LCD display 8 on which the optical image is formed by the camera 3.

[0011]

As described above, the LCD display inspection apparatus of the present invention automatically selects the rotation angle of the polarizing filter plate that minimizes the influence of the interference light caused by the reflected light on the surface of the inspection object. However, since the deterioration of the contrast of the optical image of the non-inspection object due to the interference can be minimized, the defect of the LCD display element can be easily detected. Similarly, it facilitates adjustment of the relative positional relationship between the light source, the camera, and the non-inspection object.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the image processing apparatus included in this embodiment.

FIG. 3 is a perspective view of a conventional example.

FIG. 4 is a schematic view of a general LCD display body.

[Explanation of symbols]

 1 Polarization Filter Plate 2 Lens 3 Camera 4 Filter Plate Rotation Drive Unit 5 Light Source 6, 6A Image Processing Device 7 Controller 8 LCD Display 8A Support Member 20, 20A Drive Line a Video Signal

Claims (2)

[Claims] 1. A light source for supplying incident light to an LCD display body, which is an object to be inspected, at a predetermined incident angle, and measuring light including reflected light from the LCD display body through a lens, and optics corresponding to the measuring light. A camera that produces an image and a drive voltage corresponding to the inspection pattern are generated and applied to a liquid crystal display element in the LCD display body, and a photoelectric conversion output corresponding to the measurement light is supplied and the inspection pattern is collated. LCD having an image processing device for determining the presence or absence of a defect in the LCD display body
In the display body inspection apparatus, a polarizing filter plate arranged on the front surface of the lens and rotatable about the optical axis of the lens,
The degree to which the contrast of the optical image is impaired is calculated by the interference between the drive control unit that rotationally drives the polarization filter plate and the measurement light, and the contrast reaches a predetermined threshold value. An image display apparatus further comprising a contrast processing section for sending a control signal to the drive control section as described above. 2. A means for sequentially measuring and storing a light quantity L2 of reflected light for each predetermined rotation angle pitch Δθ in a state where the contrast processing unit rotates the polarization filter plate and all the LCDs are in a non-driving state, A means for measuring and storing the light quantity L1 of the reflected light in a state in which all the LCDs are driven at a predetermined rotation angle θ1 of the polarization filter plate, and the rotation angle θ.
2. The LCD display according to claim 1, further comprising means for calculating a ratio between the light quantity L1 and the light quantity L2 in No. 1 and means for comparing a predetermined threshold value with an output of the calculation means. Physical examination device.