JP2008241254A - Lighting inspection method, and method for manufacturing plane display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting inspection method to easily detect and evaluate the fault and variation of an image pickup element, or deviation and variation of lighting conditions and a method for manufacturing a plane display device using the above method. <P>SOLUTION: A resolution chart sheet 1A and the other chart sheets 1 are set on a lighting inspection device 10 comprising a CCD camera 2 and an image processing mechanism 3 instead of a liquid crystal display panel to perform reading. The brightness value of each CCD pixel in the "reference data" obtained in early stages is stored. "Re-reading data" is acquired by reading using the same chart sheet 1 periodically, and when the brightness value of each CCD pixel is within 10% of increase or decrease on the basis of a corresponding value in the "reference data", it is determined that the CCD pixel should be normal. Almost similarly, it is determined whether or not the lighting conditions are uniform. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lighting inspection method for detecting display defects and display unevenness using an image sensor and an image processing mechanism in a final or intermediate stage of manufacturing a liquid crystal display device and other flat display devices, and a lighting inspection. The present invention relates to a method of manufacturing a flat display device including steps.

  In recent years, flat display devices such as liquid crystal display devices have been used in various fields as display devices for personal computers, word processors, TVs, etc., and as projection display devices, taking advantage of their thin, lightweight, and low power consumption characteristics. ing.

  In particular, active matrix display devices in which a switch element is electrically connected to each pixel electrode can achieve a good display image without crosstalk between adjacent pixels, and therefore are actively researched and developed. .

  When manufacturing a flat panel display device, when the display panel body is completed or when the flat panel display module is completed, wire and conductive patterns are disconnected or short-circuited, and brightness or chromaticity unevenness due to dust or partial defects is displayed. Inspection is performed to detect defects. In general, an inspection for detecting defects such as disconnection and luminance unevenness is performed by inputting a predetermined inspection signal from the signal line pad and the scanning line pad and observing the display state of the pixel. Such an inspection is called “lighting inspection” because the light source device is turned on.

  Various proposals have been made to use an automatic device equipped with a CCD camera and an image processing mechanism for the lighting inspection of the display panel (for example, Japanese Patent Laid-Open Nos. 8-145848 and 11-101712).

  In performing the lighting inspection, for example, in the case of a light-transmitting liquid crystal display device, the lighting inspection is performed while illuminating with a surface light source device (backlight) disposed on the back side. However, if the illuminance of the surface light source device varies within the surface or changes with time, the accuracy of the lighting inspection is lowered.

In order to prevent variation in illuminance of the surface light source device used for the lighting inspection, it is proposed to adjust the illuminance by measuring the illuminance at each measurement point and feeding back this data to the dimming circuit (Japanese Patent Laid-Open No. 08-2008). 106076).
Japanese Patent Laid-Open No. 08-106076 JP 08-145848 A (Patent 3160743)

  However, when directly measuring the illuminance at each position of the surface light source device, the measurement data changes relatively greatly due to some variation in measurement conditions, and the measured value varies depending on the operator performing the measurement. It was happening. For this reason, it is difficult to make the variation in luminance within the predetermined range within the light emitting surface of the surface light source device and to make the illumination condition constant. To date, an efficient method for accurately setting the lighting environment for lighting inspection to a predetermined condition has not been established.

  On the other hand, a CCD camera is usually composed of lenses and CCD elements arranged in a matrix, but the photoelectric conversion characteristics of individual CCD elements may deviate from a predetermined standard value range over time. In such a case as well, the accuracy of the lighting inspection may be reduced, so that what should be originally detected as a display defect may not be detected, or display unevenness within an allowable range may be counted as a display defect.

  The present invention has been made in view of the above-described problems, and easily detects and evaluates defects and variations in imaging elements or deviations and variations in illumination conditions during a lighting inspection of a liquid crystal display device or other flat display devices. It provides a method that can be used.

  The lighting inspection method and the flat display device manufacturing method of the present invention use a lighting inspection device including an imaging device, an image processing mechanism, and an illumination device in which imaging elements are arranged, and replace the display panel with the chart sheet. Set the lighting inspection device to perform reading, measure the data consisting of the luminance value for each image sensor, or the average luminance value for each color component in each area of the chart sheet, and use the one data as reference data The step of storing, the step of setting the same chart sheet in the lighting inspection device and reading it again to obtain the reread data, and comparing each measured value of the reread data with the corresponding measured value in the reference data And determining whether the corresponding image sensor is good or bad and whether the lighting environment is good or not based on whether the increase / decrease is within an allowable reference value. , Adjustment and setting of the data processing conditions of the image processing mechanism, the adjustment of the imaging device, repair or replacement, or adjustment of the lighting environment, characterized by comprising a step of performing repair or exchange of the lighting device.

  During lighting inspections, it is possible to easily detect and evaluate defects and variations in image sensors, or deviations and variations in lighting conditions, and based on this, adjustments for setting to predetermined environments and conditions are easily performed. be able to.

  An imaging condition uniformizing method according to an embodiment of the present invention will be described with reference to FIGS.

  First, a method for detecting and evaluating a defect in an image sensor (CCD pixel) will be described with reference to FIGS.

  As shown in FIG. 1, a test chart / sheet (screen gauge) 1 is set in the lighting inspection device 10 in place of the light transmission type liquid crystal display panel. The lighting inspection device 10 includes a CCD camera 2 and an image processing mechanism 3. Further, in the illustrated example, the backlight unit 4 that is disposed below and supplies the illumination light for transmission from the back surface side, and the auxiliary illumination light 5A that is disposed obliquely above the left and right front and rear and from the front surface side is provided. And a plurality of illumination lamps 5.

  In the right half part of FIG. 1, as a specific example of the test chart sheet 1 used for detecting and evaluating defects of the image sensor, a resolution chart sheet 1A and a color chart sheet composed of a solid pattern of one color are shown. 1B is shown.

  FIG. 2 shows data obtained by setting the resolution chart sheet 1 </ b> A on the lighting inspection apparatus 10 and reading the resolution instruction pattern 11 into 256 gradations by the CCD camera 2 and the image processing mechanism 3. The left half of FIG. 2 shows a three-dimensional graph 12 of luminance distribution data, and the right half of FIG. 2 shows the luminance distribution for each primary color of red (R), green (G), and blue (B). A table set 13 summarizing the numerical values of the data is shown. Each numerical value of the table 13 is a luminance value obtained by the corresponding CCD pixel (minimum unit image sensor). Each CCD pixel includes a color filter, and detects each color component of red (R), green (G), and blue (B).

  Data initially obtained by such a method is stored as initial “reference data” (initial data) in a storage device of the image processing mechanism 3 such as a personal computer, such as a hard disk or a DVD. Then, periodically, the same resolution chart sheet 1A is set in the lighting inspection apparatus 1, and each pattern 11 is read again in the same manner, thereby obtaining “re-import data” 13B. For example, “recapture data” 13B is acquired every two weeks or every week. Alternatively, the process of reading the resolution chart sheet 1A is incorporated into the image processing software for lighting inspection, and each time the image processing software is started, a kind of calibration using the resolution chart sheet 1A is performed in the first step. You can also make it happen.

  As shown in FIG. 3, the “reference data” 13A (the left half of FIG. 3) and the “recapture data” 13B (the right half) are compared for each CCD pixel. Then, when the luminance value of the “recapture data” is increased or decreased by, for example, 10% or more compared to the “reference data”, it is determined that an abnormality has occurred in the corresponding CCD pixel (imaging device). The reason why the increase / decrease of less than 10% is set as the allowable variation range is that it is generally known that if the increase / decrease is less than 10% (less than ± 10%), the detection of the display defect is not greatly affected. . However, if the required accuracy for detection of display unevenness is improved, the allowable fluctuation range also becomes a smaller value. On the other hand, when the variation due to the illumination environment and other factors is large, the allowable variation range has to be set to a certain extent. Thus, depending on the situation, the lower limit of the absolute value of the fluctuation value that falls outside the allowable fluctuation range is 10%, as appropriate, 5%, 8%, 12%, 15%, or 5-15. Any value within the range of% is selected.

  For CCD pixels that are determined to be abnormal, the settings in the image processing mechanism can be changed to cover the abnormality. If the degree of abnormality is so great that it cannot be corrected by software, replace the CCD camera. In some cases, repair or adjustment of the CCD pixel that has caused an abnormality is performed.

  In this way, the method of detecting an abnormality of a CCD pixel using a resolution chart sheet or other chart sheet is compared with a case where the luminance at each position on the light emitting surface of the backlight is directly measured by the CCD pixel. Thus, it is possible to detect an abnormality with extremely high accuracy. In the case of directly measuring the luminance of the light emitting surface, it is often difficult to read the change in luminance in a fine area corresponding to a high-definition CCD pixel due to light wraparound or irregular reflection.

  Next, a method for setting / adjusting the illumination environment will be described with reference to FIGS.

  FIG. 4 shows a color chart sheet 1C of 24 colors (4 × 6 columns). This color chart sheet 1C is set in the lighting inspection apparatus 10 of FIG. 1, and a red part (red color patch) 1C-R, a green part (green color patch) 1C-G and a blue part 1C-B, and The other color portions are imaged by the CCD camera 2. Thus, as shown in FIG. 5, the red component luminance distribution 14 </ b> R and the green component luminance for each of the red portion 1 </ b> C-R, the green portion 1 </ b> C-G, the blue portion 1 </ b> C-B, and the other color portions. The distribution 14G and the luminance distribution 14B of the blue component are obtained. Then, an average luminance value of each color component is obtained in each color part. In this way, 24 × 3 = 72 average luminance values are obtained in the illustrated example.

  As in the case of detecting and evaluating defects in the image sensor, the initial “reference data” is stored in the storage device of the image processing mechanism 3, and the same color chart sheet 1C is set periodically. , "Re-import data" is acquired. When all the numerical values (average luminance values of each color component for each color part) included in the “recapture data” stay within an increase / decrease within 20% with respect to the corresponding value in the “reference data”, for example, Judge that the environment is constant. That is, in the example shown in the figure, it is determined that the illumination environment is constant when the 72 average luminance values are all within 20% of increase / decrease over time. Here, the allowable variation range is within 20%. In general, even if an increase or decrease of more than 20% occurs in one or a very small number of measurement values within this range, in general, detection of display defects and display unevenness is detected. This is because it was known that it does not affect However, when the demand for display defects and display unevenness is improved, it is necessary to set a smaller range of increase / decrease as the allowable variation range, and for products with low required performance, the larger range of increase / decrease is set as the allowable variation range. be able to. Therefore, the increase / decrease value used as a criterion for determination here can be selected from a value of 5%, 10%, 15%, 25%, etc., depending on the situation, in addition to 20%.

  If it is determined that the lighting environment is not constant, the variation is covered by adjusting the setting value of the software of the image processing mechanism 3, or the lighting device is adjusted. For example, replacement of a cold cathode tube provided in the backlight, adjustment of an input system for causing the LED to emit light, and the like can be performed.

  If the color chart sheet 1C or other chart sheet as described above is used to detect a time-dependent shift in the luminance distribution of the backlight 4, the light emitting surface of the backlight directly with a CCD camera or other light receiving element. Compared with the case where the luminance at each position is detected, the measurement accuracy can be remarkably improved.

  A commercially available product can be used as it is for the test chart sheet 1 of the above embodiment. Resolution chart sheet 1A includes, for example, “ISO12233 resolution chart” from the Camera & Imaging Products Association of Japan, “Screen Gauge” from the Imaging Society of Japan, “Ladder Pattern Chart” from FUJIFILM Imagetech Co., Ltd. It can be used as it is. For the color chart sheet, the color checker chart (24 colors) of GretagMacbeth can be used as it is. In some cases, a commercially available color chart sheet may be superposed on or bonded to a glass plate to have the same thickness as the liquid crystal display panel.

  Resolution chart sheets (resolution charts) and other test chart sheets are generally light-transmitting and a test pattern is formed on a colorless or transparent glass or plastic substrate by printing, etc. It has been done. Any sheet or film (hereinafter also referred to as a sheet including a sheet having a small thickness) can be used as long as it has appropriate transparency (light transmittance and haze) and durability. is there. Preferable examples include olefin resins such as polymethylpentene resin, saturated polyester resins such as PET (polyethylene terephthalate) and polyethylene naphthalate, and sheets having a thickness of 50 to 500 μm, such as methacrylic resins and acrylic resins. Can do.

  A predetermined pattern is provided on the transparent sheet serving as the base material by a general printing method such as photolithography. The transparent sheet of the base material is preliminarily subjected to treatment for improving printability as necessary. In some cases, a pattern can be provided by an ink jet drawing method or an offset method.

  When the liquid crystal display panel is of a reflective type, a similar chart sheet that is commercially available for reflection can be used. The chart sheet for reflection is generally composed of an opaque resin layer whose pattern by printing or the like contains a pigment. In addition, as the base resin sheet, a substantially perfect white plate can be used by kneading a white pigment such as titanium oxide.

  The lighting inspection including the evaluation and correction of the imaging conditions as described above should be performed after the display panel body is assembled and before or after the TCP (tape carrier package) or driving PCB is assembled (that is, after the display panel is completed). Can do. In some cases, it may be performed after the backlight device or the like is assembled.

  The array substrate and the counter substrate in the flat display device are manufactured by, for example, a method described in JP-A-9-160076, JP-A-2000-267595, JP-A-2000-330484, or JP-A-2001-339070. be able to.

  The above-described method for detecting and evaluating defects in CCD pixels is not limited to the manufacture of liquid crystal display devices, but can also be used in the manufacture of organic EL display devices and other self-luminous flat display devices. .

  In the above description, the image pickup device is described as being composed of a CCD, but the same is true even if it is composed of a CMOS or the like.

It is a block diagram which shows typically a mode that a resolution chart sheet or a color chart sheet is set to the lighting inspection apparatus. FIG. 6 is a screen composite diagram showing a state where a resolution instruction pattern on a resolution chart sheet is read to acquire data of a three-dimensional graph and a table as a combination of monitor screens. It is a screen composite diagram showing a state in which each luminance value of “reference data” obtained in the initial stage is compared with each luminance value of “recapture data” obtained at the time of subsequent inspection. It is a top view which shows the 24 color chart / sheet used for the setting / adjustment of illumination environment. For each color part (color patch) in the color chart sheet of FIG. 4, the luminance distribution of each of the three primary color components is obtained, and further the average luminance is shown by an array of three-dimensional graphs and numerical values attached thereto. It is one monitor screen figure.

Explanation of symbols

1 Chart sheet 1A Resolution chart sheet
1B Solid color chart sheet 1C 24 color chart sheet
DESCRIPTION OF SYMBOLS 10 Lighting inspection apparatus 11 Pattern 12 Three-dimensional graph of luminance distribution data
13 Table 13A “Reference data” 13B “Re-import data”
2 CCD camera 3 Image processing mechanism 4 Backlight unit 5 Illumination lamp

Claims (4)

In a lighting inspection method using a lighting inspection apparatus including an imaging device in which imaging elements are arranged, an image processing mechanism, and a lighting device,
Instead of a display panel, a chart sheet is set in the lighting inspection device and read, and data consisting of luminance values for each image sensor or data consisting of average luminance values for each color component in each area of the chart sheet is read. A process of acquiring;
Storing the one data as reference data, setting the same chart sheet in the lighting inspection device, reading again and obtaining reread data,
Comparing each measurement value of the reread data with the corresponding measurement value in the reference data, and determining whether the increase or decrease is within the allowable variation, and determining whether the corresponding image sensor is good or bad, and the lighting environment,
And adjustment or setting of data processing conditions by the image processing mechanism, adjustment, repair or replacement of the image sensor, or adjustment of the lighting environment and repair or replacement of the lighting device based on this determination. Lighting inspection method.   In determining whether each image sensor is good or bad, data including luminance values for each image sensor is acquired using a resolution chart sheet or a color chart sheet, and when the increase / decrease is 10% or more, there is an abnormality in the image sensor. The lighting inspection method according to claim 1, wherein the lighting inspection method is determined to have occurred.   In determining whether the lighting environment is good or bad, a color chart sheet composed of a plurality of color portions is used to acquire data consisting of average luminance values in each color portion, and lighting is performed when all the average luminance values increase or decrease within 20%. The lighting inspection method according to claim 1, wherein it is determined that the environment is constant when viewed from a reference.   The manufacturing method of the flat display apparatus using the lighting inspection method in any one of Claims 1-3.