JP2004279891A - Inspecting apparatus and inspection method for liquid crystal cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection apparatus and inspection method capable of inspecting the display unevenness of a liquid crystal cell before finishing assembly of a liquid crystal module without being affected by inspector's capabilities. <P>SOLUTION: The inspection apparatus 10 is equipped with an oscillator 12 which oscillates a laser 18a, a half mirror 20 which splits the laser 18a to the first laser 18b and the second laser 18c between the oscillator 12 and a color filter substrate 24. a first detector 14 which detects the quantity of light of the first laser 18b, a second detector 16 which detects the quantity of light of the second laser 18c transmitted through the liquid crystal cell 28 and an arithmetic means which calculates the transmittance of the second laser 18c to the liquid crystal cell 28 by the quantity of light detected with the first detector 14 and the quantity of light detected with the second detector 16. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inspection device and an inspection method for inspecting display unevenness of a liquid crystal cell.
[0002]
[Prior art]
A plurality of inspections are performed in a manufacturing process of a liquid crystal module. By performing a plurality of inspections, defective products are prevented from flowing into the subsequent processes, and the yield is prevented from deteriorating.
[0003]
The liquid crystal module is a display device in which a backlight and a driver circuit are attached to a liquid crystal cell in which liquid crystal is sealed in the gap between the array substrate and the color filter substrate with the array substrate and the color filter substrate facing each other. is there.
[0004]
It is difficult to inspect the display unevenness of the liquid crystal module. This is because display unevenness has a gradual change in luminance compared to a shining bright pixel, and display unevenness is more difficult to recognize. In addition, there is a large difference in the detection of display unevenness due to the visual inspection of the inspector. Even if a certain inspector can find display unevenness, another inspector may not find display unevenness.
[0005]
The display unevenness of the liquid crystal module may be caused by a defective liquid crystal cell and a defective backlight. If display unevenness of the liquid crystal module is found, it is necessary to remove the backlight from the liquid crystal cell and inspect the liquid crystal cell and the backlight. When disassembling the liquid crystal module, parts of the liquid crystal module may be damaged. Disassembly of the liquid crystal module is a proof that defective products have flowed into a post-process, and is a cause of a decrease in the yield of the liquid crystal module and an increase in manufacturing cost.
[0006]
Patent Document 1 describes a method for measuring the transmittance of a sample and quantifying the degree of unevenness. The light from the light projection head is transmitted through the sample, and the transmitted light is received by the light receiving head to determine the transmittance. The transmittance at a position other than the measurement position is inferred from surrounding measurement values. However, when the light output of the light projection head is unstable, an accurate transmittance cannot be obtained. The transmittance is not measured at all the positions to be measured, but there are also positions where the transmittance is obtained by analogy, and the transmittance is not accurately measured at all the positions.
[0007]
[Patent Document 1] Japanese Patent Application Laid-Open No. 5-196570 (FIG. 1)
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide an inspection apparatus and an inspection method capable of inspecting display unevenness in a liquid crystal cell before assembling a liquid crystal module without being affected by the ability of an inspector.
[0009]
[Means for Solving the Problems]
The gist of the liquid crystal cell inspection apparatus of the present invention is a liquid crystal cell inspection apparatus including a color filter substrate, an array substrate facing the color filter substrate with a gap, and a liquid crystal sealed in the gap. An oscillator that oscillates a laser, a half mirror that divides the laser into a first laser and a second laser between the oscillator and the color filter substrate, and a first mirror that detects a light amount of the first laser. A detector, a second detector for detecting an amount of the second laser transmitted through the liquid crystal cell, and a transmittance of the second laser to the liquid crystal cell based on the amount of light detected by the first detector and the amount of light detected by the second detector. Means for calculating. By calculating the transmittance of the laser beam transmitted through the liquid crystal cell, display unevenness can be quantitatively inspected.
[0010]
The liquid crystal cell includes means for scanning the second laser. By scanning the second laser, the second laser can be applied to all portions of the liquid crystal cell.
[0011]
The liquid crystal cell is divided into pixels arranged in rows and columns, and the pixels are further divided into a plurality of sub-pixels. The means for calculating the transmittance includes means for calculating the transmittance of each sub-pixel. By calculating the transmittance for each sub-pixel, display unevenness depending on the sub-pixel can be detected.
[0012]
Means for determining a change in transmittance of the sub-pixel. A portion having display unevenness can be detected from a change in transmittance between subpixels of the same color of adjacent pixels.
[0013]
The color filter substrate and the array substrate have electrodes for driving liquid crystal, and include means for applying a voltage to the electrodes. The inspection items of the liquid crystal cell can be changed depending on whether or not a voltage is applied to the electrodes.
[0014]
The gist of the liquid crystal cell inspection method according to the present invention is to inspect a liquid crystal cell including a color filter substrate, an array substrate facing the color filter substrate with a gap, and a liquid crystal sealed in the gap. A method of oscillating a laser, splitting the laser into a first laser and a second laser, detecting an amount of light of the first laser, and a second laser transmitted through the liquid crystal cell. Detecting the amount of light of the first laser and calculating the transmittance of the second laser to the liquid crystal cell from the amount of the second laser transmitted through the liquid crystal cell.
[0015]
Scanning the second laser in the liquid crystal cell.
[0016]
The liquid crystal cell is divided into pixels arranged vertically and horizontally, the pixels are divided into a plurality of sub-pixels, and the step of calculating the transmittance is performed for each of the sub-pixels.
[0017]
Using the transmittance calculated for each of the sub-pixels to determine a change in transmittance between sub-pixels of the same color of adjacent pixels.
[0018]
Selecting whether to drive or not to drive the liquid crystal.
[0019]
[Embodiment of the present invention]
An embodiment of a liquid crystal cell inspection apparatus and an inspection method according to the present invention will be described with reference to the drawings. The inspection is an inspection for display unevenness of the liquid crystal cell.
[0020]
The liquid crystal cell to be inspected includes a color filter substrate, an array substrate facing the color filter substrate with a gap, and a liquid crystal sealed in the gap. The liquid crystal cell is divided vertically and horizontally into a plurality of pixels. Each pixel is divided into three sub-pixels (or picture elements). The three primary colors (R (red), G (green), and B (blue)) of light are generated by the sub-pixels, and the color of one pixel is expressed. Further, the liquid crystal cell is provided with an alignment film and an ITO (Indium Tin Oxide) which is an electrode for driving the liquid crystal on a color filter substrate or an array substrate.
[0021]
As shown in FIG. 1, the inspection apparatus 10 includes an oscillator 12 that oscillates a laser 18a, and a half mirror 20 that divides the laser 18a into a first laser 18b and a second laser 18c between the oscillator 12 and the color filter substrate 24. A first detector 14 for detecting a light amount of the first laser 18b, a second detector 16 for detecting a light amount of the second laser 18c transmitted through the liquid crystal cell 28, and a light amount and a second detector detected by the first detector 14. An arithmetic unit (not shown) for calculating the transmittance of the second laser 18c to the liquid crystal cell 28 based on the amount of light detected by the light source 16 is provided. In this specification, the light amount is a laser power.
[0022]
The power of the second laser 18c is set to 8 μJ or less so that the liquid crystal does not vaporize. Further, the amount of light detected by the second detector 16 is set to 18 mJ / mm ² or less so that the alignment film and ITO are not affected by the heat of the second laser 18 c.
[0023]
The laser 18a is a three-color independent light source or a three-color same light source. The three-color independent light source oscillates the laser 18a of each wavelength of RGB with each light source. The same light source of three colors oscillates the laser 18a of each wavelength of RGB with the same light source.
[0024]
There are two types of three-color independent light sources: a type in which the laser 18a of each of the RGB wavelengths has a different optical axis, and a type in which the laser 18a has the same optical axis. In the type 12a having a different optical axis of the laser 18a shown in FIG. 2A, the optical axes of the three colors are shifted by the pitch of the sub-pixel of the liquid crystal cell. If the RGB arrangement of the liquid crystal cell 28 is a stripe arrangement as shown in FIG. 3, it is possible to simultaneously irradiate each of the RGB sub-pixels 34 with the second laser 18c. Therefore, display unevenness of each of the RGB sub-pixels 34 can be inspected simultaneously.
[0025]
The type 12b in which the optical axes of the three colors are coaxial as shown in FIG. 2B synchronizes the oscillating light source with the sub-pixel 34 to be inspected. For example, when irradiating the second laser 18c to the R sub-pixel 34, the R laser 18a is oscillated.
[0026]
In the type 12b of the three-color independent light source shown in FIG. 2B, since the prism 32 has one optical axis, the inspection is performed in synchronization.
[0027]
The type 12c of the same light source of three colors shown in FIG. 2 (c) performs the inspection while maintaining synchronization in the same manner as the type 12b of the three color independent light sources having the same optical axis.
[0028]
The three-color independent light sources shown in FIGS. 2A and 2B use laser diodes 30R, 30G, and 30B of each color. For the same light source of three colors, a He-Cd laser 12c, which is a metal vapor laser, or the like is used.
[0029]
The reason for using the lasers 18 corresponding to each color of RGB will be described. The color filter substrate 24 has a coloring layer corresponding to each color of the sub-pixel 34. Each color of the colored layer can transmit light of a wavelength in a band corresponding to each color. However, the laser 18a is light having a single wavelength, and the laser 18a having a wavelength other than the band corresponding to the color of the colored layer cannot pass through the colored layer. Therefore, a laser 18a corresponding to each of the RGB colors of the sub-pixel 34 is required. By using the lasers 18 corresponding to the respective colors of RGB, it is possible to inspect the display unevenness based on the transmittance of each of the sub-pixels 34.
[0030]
In the present invention, display unevenness is inspected using the transmittance of the laser 18a in the liquid crystal cell 28. In order to determine the transmittance of the laser 18a, the first detector 14 needs to be disposed at the point C. However, when the first detector 14 is disposed at the point C, the laser 18a cannot pass through the liquid crystal cell 28. Therefore, the laser 18a is divided into the first laser 18b and the second laser 18c by the half mirror 20, and the transmittance of the second laser 18c is obtained. The ratio between the first laser 18b and the second laser 18c split by the half mirror 20 is constant. For example, the ratio is 1: 1. The transmittance is obtained by dividing the light amount of the second laser 18c by the light amount of the first laser 18b.
[0031]
Since the inspection is performed for each sub-pixel 34, the second laser 18 c is converged to the size of the sub-pixel 34 when transmitting through the liquid crystal cell 28. This is for preventing a TFT (Thin Film Transistor) of the array substrate 26 from malfunctioning due to photo leak when performing the inspection by driving the liquid crystal, as described later, and performing a highly accurate inspection. The inspection device 10 may include a lens for converging the second laser 18c as described above. For example, the size of the spot of the second laser 18c is about 18 μm × 24 μm, and is at least about 50 μm × 50 μm or less.
[0032]
Even if the output of the laser 18a oscillated by the oscillator 12 is unstable, if the liquid crystal cell 28 is normal, the second laser obtained by dividing the light amount of the first laser 18b from the light amount of the second laser 18c. The transmittance of 18c becomes constant. Therefore, the transmittance of the second laser 18c is used for inspection of display unevenness.
[0033]
The laser spot of the second laser 18c is caused to scan on the surface of the liquid crystal cell 28. The means for performing scanning is a means for holding the liquid crystal cell 28 or a transparent plate on which the liquid crystal cell 28 is placed and through which the second laser 18c passes. The second laser 18c can be scanned by the holding means or the transparent plate moving the liquid crystal cell 28. By scanning the second laser 18c, a difference in the transmittance of the second laser 18c in the sub-pixel 34 can be obtained.
[0034]
Using the transmittance calculated by the arithmetic means, there are provided means for determining a change in transmittance between adjacent sub-pixels 34 of the same color of pixels, and means for determining unevenness. The change in transmittance is a difference between the transmittances of the sub-pixels 34. A portion where there is a change equal to or larger than a threshold determined by the liquid crystal module is determined to be uneven. The calculation means, the means for determining the transmittance, and the means for determining unevenness may be constituted by a program such as a computer.
[0035]
Means are provided for graphing the transmittance of each sub-pixel calculated by the arithmetic means for each color of the sub-pixel. As shown in FIG. 4 and FIG. 5, by plotting the transmittance in a graph, the change in the transmittance can be easily understood, and unevenness can be detected from the graph. 4 and 5, the transmittance indicates the ratio of the amount of light detected by the first detector 14 and the amount of light detected by the second detector 16 as a relative value of the amount of laser reflection and absorption. In FIG. 4, there is a difference in transmittance at a position of about 50 to 100 mm, and it is determined to be uneven. In FIG. 4, the peaks at both ends are portions other than the display area of the liquid crystal cell 28. FIG. 5 shows that the transmittance changes periodically and the transmittance can be measured in units of sub-pixels 34.
[0036]
A mirror 22 is provided between the oscillator 12 and the liquid crystal cell 28. The angle of the mirror 22 is adjusted so that the angle of the second laser 18c with respect to the liquid crystal cell 28 becomes 90 °.
[0037]
The color filter substrate 24 and the array substrate 26 have electrodes. When a voltage is applied to this electrode, the liquid crystal is driven. The inspection device 10 includes a unit that applies a voltage to the electrode. The display unevenness detected differs depending on whether or not the voltage is applied. When a voltage is applied, display unevenness due to the structure of the array substrate 26, a cell gap, or the like can be detected. When no voltage is applied, display unevenness due to components that are not affected by liquid crystal driving, such as the color filter substrate 24, can be detected. Inspection items differ depending on whether or not a voltage is applied.
[0038]
An inspection method of the liquid crystal cell 28 will be described. Whether or not to apply a voltage to the electrode of the liquid crystal cell 28 is selected according to the inspection item, and the liquid crystal is driven or not driven.
[0039]
A laser 18a is oscillated by the oscillator 12. With respect to the laser 18a that oscillates, if the arrangement of the sub-pixels 34 of the liquid crystal cell 28 is a stripe arrangement and the optical axes of the three colors of the laser 18a are different, three lasers oscillate simultaneously. If the optical axes of the three colors are the same, the laser 18a oscillating to the color of the sub-pixel 34 to be inspected is synchronized.
[0040]
Half mirror 20 divides laser 18a into first laser 18b and second laser 18c. The light amount of the first laser 18b is detected by the first detector 14 at the destination. Since the first laser 18b does not transmit through the liquid crystal cell 28, if the ratio of the light amounts of the first laser 18b and the second laser 18c is 1: 1, the light amount at the point C on the surface of the liquid crystal cell 28 is the same. .
[0041]
The traveling direction of the second laser 18c is adjusted by the mirror 22 so as to be incident on the liquid crystal cell 28 at an angle of 90 °. The second laser 18c passes through the liquid crystal cell 28, and the amount of light is detected by the second detector 16.
[0042]
The calculating means calculates the transmittance of the second laser 18c by dividing the light amount of the second laser 18c by the light amount of the first laser 18b.
[0043]
The second laser 18c is scanned, and the transmittance at each sub-pixel 34 is obtained to make a graph. The position where the transmittance changes is detected. That is, the difference in the transmittance between the sub-pixels 34 of the same color of the adjacent pixels is obtained, and a portion having a change equal to or more than the threshold determined by the liquid crystal module is determined to be uneven.
[0044]
As described above, according to the present invention, display unevenness of the liquid crystal cell 28 can be quantitatively detected. The presence or absence of display unevenness due to the difference in inspector's ability is eliminated. Since the display unevenness can be inspected at the time of the liquid crystal cell 28, defective products of the liquid crystal cell 28 can be found out before assembling the liquid crystal module. Therefore, it contributes to improvement in yield and reduction in manufacturing cost. Further, since the inspection is performed for each sub-pixel 34, display unevenness depending on RGB of the sub-pixel 34 can be detected.
[0045]
Further, the inspection for display unevenness may be performed for each area of the liquid crystal cell 28. As shown in FIG. 6, the area is divided into a plurality of areas 36a and 36b, and a difference is calculated from the transmittance between the areas 36a and 36b by using the transmittance between the areas 36a and 36b having the common portion 36c. To determine unevenness. In order to make the determination of unevenness as described above, the inspection apparatus 10 calculates the transmittance of each area 36a, 36b using the transmittance of each sub-pixel calculated by the arithmetic means, and determines the transmittance of each area 36a, 36b. Means for calculating a difference in transmittance, and means for determining unevenness from the obtained difference are included. Each of these means may be configured by a computer program.
[0046]
In the case of inspecting the display unevenness in units of area, by increasing the overlap 36c between the areas 36a and 36b and the areas 36a and 36b, it is possible to minimize influences such as measurement error and thermal fluctuation of the oscillator. On the other hand, the inspection resolution can be increased by reducing the overlap 36c and the areas 36a and 36b. As for the overlap 36c between the areas 36a and 36b and the areas 36a and 36b, an optimum value is searched from the specification of the target liquid crystal module and the measured absolute amount.
[0047]
The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. In addition, the present invention can be implemented in various modified, modified, and changed forms based on the knowledge of those skilled in the art without departing from the scope of the present invention.
[0048]
【The invention's effect】
According to the present invention, display unevenness of a liquid crystal cell can be quantitatively detected regardless of the ability of an inspector. Detection of display unevenness can be performed at a certain level. Since the display unevenness can be inspected at the time of the liquid crystal cell, a defective product can be found out before assembling the liquid crystal module. Therefore, it contributes to improvement in yield and reduction in manufacturing cost. Since the inspection is performed for each sub-pixel, display unevenness depending on the RGB of the sub-pixel can be detected. Since display unevenness can be detected in the liquid crystal cell, when display unevenness is found in the liquid crystal module, it is immediately known that the display unevenness is caused by a defective backlight.
[Brief description of the drawings]
FIG. 1 is a view showing an apparatus for inspecting display unevenness of a liquid crystal cell according to the present invention.
2A and 2B are diagrams showing a configuration of each laser, in which FIG. 2A is a diagram in which optical axes are divided by three-color independent light sources, and FIG. 2B is a diagram in which optical axes are identical by three-color independent light sources. , (C) is a diagram of the same light source for three colors.
FIG. 3 is a diagram in which sub-pixels are arranged in a stripe array.
FIG. 4 is a graph showing transmittance.
FIG. 5 is a diagram illustrating a state in which transmittance can be measured for each sub-pixel.
FIG. 6 is a diagram for measuring a change in transmittance by dividing a liquid crystal cell into a plurality of regions.
[Explanation of symbols]
10: Inspection device 12, 12a, 12b, 12c: Oscillator 14, 16: Detector 18a, 18b, 18c: Laser 20: Half mirror 22: Mirror 24: Color filter substrate 26: Array substrate 28: Liquid crystal cells 30R, 30G, 30G : Laser diode 34: sub-pixel 36a, 36b, 36c: area

Claims (10)

A color filter substrate,
An array substrate facing the color filter substrate with a gap,
A liquid crystal sealed in the gap,
An inspection apparatus for a liquid crystal cell including:
An oscillator that oscillates a laser,
A half mirror that divides the laser into a first laser and a second laser between the oscillator and the color filter substrate;
A first detector for detecting a light amount of the first laser;
A second detector for detecting a light amount of a second laser transmitted through the liquid crystal cell;
Means for calculating the transmittance of the second laser to the liquid crystal cell from the amount of light detected by the first detector and the amount of light detected by the second detector;
Inspection equipment including. The inspection apparatus according to claim 1, further comprising a unit configured to scan the liquid crystal cell with the second laser. 3. The liquid crystal cell according to claim 2, wherein the liquid crystal cell is divided into vertically and horizontally arranged pixels, the pixels are divided into a plurality of sub-pixels, and the means for calculating the transmittance includes means for calculating the transmittance for each sub-pixel. Inspection equipment. The inspection apparatus according to claim 3, further comprising a unit that obtains a change in transmittance of the sub-pixel. The inspection apparatus according to any one of claims 1 to 4, wherein the color filter substrate and the array substrate have electrodes for driving liquid crystal, and include means for applying a voltage to the electrodes. A color filter substrate,
An array substrate facing the color filter substrate with a gap,
A liquid crystal sealed in the gap,
A liquid crystal cell inspection method comprising:
Oscillating a laser;
Splitting the laser into a first laser and a second laser;
Detecting the amount of light of the first laser;
Detecting a light amount of the second laser transmitted through the liquid crystal cell;
Calculating the transmittance of the second laser to the liquid crystal cell based on the light intensity of the first laser and the light intensity of the second laser transmitted through the liquid crystal cell;
Inspection method including. The inspection method according to claim 6, further comprising scanning the second laser in the liquid crystal cell. 8. The inspection method according to claim 6, wherein the liquid crystal cell is divided into pixels arranged vertically and horizontally, the pixels are divided into a plurality of sub-pixels, and the step of calculating the transmittance is performed for each of the sub-pixels. The inspection method according to claim 8, further comprising: using a transmittance calculated for each of the sub-pixels, determining a change in transmittance between sub-pixels of the same color of adjacent pixels. The inspection method according to claim 6, further comprising selecting whether to drive or not to drive the liquid crystal.

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