JP2000346744A - Method and device for measuring color characteristic of color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the chromaticity value of a color filter for evaluating accurately without being affected by coloring density distribution in a pixel by increasing the ratio of the area of a measurement region for the area of a pixel opening as much as possible. SOLUTION: A measurement region 6 is set so that ratio of an area for the area of a pixel opening 5 is 30-100%. When the area of the measurement region 6 is set to be 30% or larger, the chromaticity value of a pixel can be obtained further accurately. Also, when the area is set to be 100% or less, overlapping with a frame (light-shielding part) 2 for forming the pixel opening 5 is not made. The shape of the measurement region 6 is preferably similar to that of the pixel opening 5 or rectangle. Also, when the measurement region 6 is rectangle, an angle formed between a direction where the change in the coloring density distribution in the pixel of the color filter is the largest and one side of the rectangle of the measurement region 6 is preferably within 15 degrees, and if possible measurement region 6 is set to that the angle is 0 degrees, that is, to make them parallel with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and apparatus for measuring color characteristics for evaluating a color filter used in a liquid crystal display device or the like.

[0002]

2. Description of the Related Art Generally, a liquid crystal display device is mounted on a personal computer, a word processor, a pachinko game console, an automobile navigation system, a small television, and the like, and the demand has been increasing in recent years. However, liquid crystal display devices are expensive and demands for cost reduction are increasing year by year.

A color filter constituting a liquid crystal display device is configured by arranging pixels of red (R), green (G), blue (B), etc. on a transparent substrate. Is provided with a black matrix for shielding light in order to enhance display contrast.

Conventionally, as a method for producing a color filter, a dyeing method, a pigment dispersion method, an electrodeposition method, a printing method and the like have been known.

[0005] The pigment dispersion method is a process of forming a photosensitive resin layer in which a pigment is dispersed on a glass substrate and patterning the same to obtain a monochromatic pattern three times for three colors of R, G and B. By repeating this, a color filter is formed.

In the dyeing method, a layer of a water-soluble polymer material, which is a material for dyeing, is formed on a glass substrate, formed into a desired pattern by photolithography, and the glass substrate is placed in a dyeing tank. The process of obtaining a colored pattern by immersion is repeated three times for three colors of R, G, and B to form a color filter.

The electrodeposition method involves forming a transparent electrode pattern on a glass substrate, immersing the glass substrate in an electrodeposition coating solution containing a pigment, a resin, an electrolytic solution and the like to electrodeposit a single color. The color filter is formed by repeating and firing three times for three colors of R, G, and B.

The printing method is to repeat printing three times using a composition in which a pigment is dispersed in a thermosetting resin,
This is a method in which R, G, and B colors are separately applied, and then the resin is thermally cured.

The common features of the above four methods are R,
It is necessary to repeat the same process three times for coloring the three colors G and B, and the number of processes is large, so that the yield is reduced and the cost is increased.

Furthermore, the electrodeposition method is difficult to apply to a TFT type liquid crystal element (an active matrix driving type liquid crystal element using a TFT (thin film transistor)) because the shape of a pattern that can be formed is limited. Further, the printing method has problems such as poor resolution and difficulty in responding to pattern miniaturization.

In order to overcome these problems, there has been proposed a technique of forming a color filter pattern by discharging ink on a glass substrate by an ink jet head. In such an ink jet system, R, G,
The formation of the pixels of each color B can be performed in one step,
A significant simplification of the manufacturing process and a significant cost reduction effect can be obtained.

The measurement of the color characteristics of a color filter manufactured by the above-described method is generally performed by using the SEMI standard,
Draft Doc., Which is being considered for standardization by the FPD Technology Committee and the FPD Color Filter Committee, # 284
6. A method based on a method represented by “Method for measuring color characteristics of color filter” is mainly used. In the measurement method,
As a spectrophotometer device specification, the spectral wavelength range is 38.
It is considered appropriate that the wavelength is from 0 nm to 780 nm, the wavelength resolution is 10 nm or less, and the measurement spot diameter can be adjusted from about 2 μm to 50 μm. It also states that there is no problem if the microscope stage has a movable range and accuracy that does not hinder measurement. In the spectroscopic measurement method, first, spectroscopic measurement is performed on a reference substrate serving as a reference for comparison with the transmittance of the colored portion, generally a glass substrate used for a color filter. Next, spectral measurement of the colored portion formed on the glass substrate is performed. The ratio at each wavelength obtained by the measurement is the spectral transmittance. Then, if necessary, a CIE1931xy chromaticity diagram or CIE1976L ^* a ^* is obtained from the spectral transmittance obtained by the measurement.
b ^* Represented as a chromaticity value according to a standard such as a color system.

[0013]

At present, a pigment dispersion method is mainly used as a method for producing a color filter, but various production methods other than the pigment dispersion method have been developed as described above. Among them, a color filter in which the cross-sectional shape of a colored portion in a pixel is not uniform and has a certain distribution has been developed, and a color filter in which the cross-sectional shape of the colored portion plays a functional role has been disclosed.

For example, Japanese Patent Application Laid-Open No. 7-32529 discloses an example of a color filter that functionally uses the convex shape of a colored portion.
9 and JP-A-9-304763.

In the color filter described in JP-A-7-325299, the colored portion is provided by intaglio offset printing with a printing ink containing a pigment, and has a convex section.
In addition, it has a shape in which the maximum thickness is larger than the total thickness of the portions overlapping the light-shielding film. For this reason, it is disclosed that in a measuring method for measuring the intensity unevenness of the reflected light by irradiating a sodium D line of 589 nm, the intensity unevenness hardly occurs and the display quality of the liquid crystal display device is improved. In this case, since the coloring density distribution in the pixel depends on the cross-sectional shape of the coloring portion, a coloring density distribution in the pixel occurs in which the density at the pixel central portion is high and the density at the light-shielding portion boundary portion is low.

Japanese Patent Application Laid-Open No. 10-206627 discloses an example in which a colored cross-sectional shape becomes convex in a method of manufacturing a color filter by an ink jet method. Since the color filter disclosed in this publication rises in a convex shape as shown in FIG. 1D of the publication in a drying step after filling with ink, a protective film is required to supplement flatness. I have. In this case, since the colored portion is convex, the density at the center of the pixel is high, and the density at the boundary with the light-shielding portion is low. Therefore, the pixel has a convex coloring density distribution in the pixel.

Further, examples in which the cross-sectional shape of the colored portion is concave are disclosed in JP-A-10-68810 and JP-A-9-258.
No. 208, for example. JP-A-10-68
The technique described in the No. 810 method is a method of manufacturing a color filter by filling a concave master with ink, forming a resin layer on an upper portion after drying, and then peeling the resin layer from the master. As shown in FIG. 1 (C) of the publication, the density of the colored portion is low at the center of the pixel, and the density is high around the pixel which is the boundary of the light shielding portion. Therefore, in this case, the pixel has a concave color density distribution. Japanese Patent Application Laid-Open No. 9-258208 discloses a color filter substrate capable of controlling the position of the axis of symmetry of an axis-symmetric alignment in a liquid crystal display device of an axis-symmetric alignment mode by making the surface of a coloring layer concave. And has the effect of improving the display quality. In this case, in the color density distribution in the pixel, the density at the center of the pixel is low and the density at the boundary of the light-shielding portion is high.

As described above, in a color filter in which the cross-sectional shape of the colored portion is not uniform and the film thickness of the colored portion is distributed, a colored density distribution occurs in the colored portion in the pixel. Therefore, the Draft Doc. Performing the measurement in accordance with # 2846 “Method for measuring color characteristics of color filter” causes a problem that the color characteristics cannot be measured accurately depending on the measurement conditions. The reason is that, since the measurement spot diameter is 50 μm or less, various chromaticity values are obtained depending on the size of the measurement spot diameter in a color filter having a color density distribution in a pixel. For example, the color density distribution in the pixel is low at the pixel center,
When the density is high at the boundary of the light-shielding portion, a small measurement spot results in a chromaticity value with low color purity, and a large measurement spot results in a chromaticity value with high color purity. It becomes unknown whether it shows. The panel actually assembled using the color filters measured as described above also has a problem that the chromaticity value is largely distorted.

An object of the present invention is to provide a method and a measuring apparatus for solving the above-mentioned problems, accurately measuring the chromaticity value of a color filter without being affected by the color density distribution in a pixel, and performing a highly accurate evaluation. To provide.

[0020]

According to the present invention, there is provided a color filter having a color density distribution in a pixel, which solves the above-mentioned problems.
This is a measurement method which is considered in order to obtain a chromaticity value comparable to that of a color filter having a substantially uniform coloring density in a pixel.

That is, the present invention is a method for measuring the chromaticity characteristics of a color filter by measuring the spectral spectrum of a colored region, wherein the ratio of the area of the measured region to the area of the pixel opening is 30% to 100%. %, Which is a method for measuring the color characteristics of a color filter.

In the present invention, it is preferable that the measurement region has a shape similar to the shape of the pixel opening, a shape having a curvature at the corner of the similar shape, a square, or a shape having a curvature at the corner of the square. In addition, the angle between the direction of the largest change in the color density distribution in the pixel of the color filter and one side of the square of the measurement area is within 15 °, and particularly the direction of the largest change in the color density distribution, Desirably, it is parallel to one side of the square.

The present invention is also an apparatus for measuring the color characteristics of a colored region of a color filter, wherein the shape of the stop is similar to the shape of the pixel opening, and the similar shape has a curvature at the corner. , A quadrangle, or a shape in which a corner of the quadrangle has a curvature.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a measuring method according to the present invention, a color density distribution which depends on a concave or convex shape in a pixel is not measured with a relatively small spot diameter, but includes the color density distribution. By measuring the area, the chromaticity value of the colored portion of the pixel can be obtained more accurately. This will be described in detail below.

In the present invention, the ratio of the area of the measurement region to the area of the pixel opening is 30% to 100%.
Set so that By setting the area ratio to 30% or more, the chromaticity value of the pixel can be obtained more accurately. Further, by setting the content to 100% or less, there is no overlap with the frame forming the pixel opening. The shape of the measurement region is preferably similar to or similar to the shape of the pixel opening. Also, if the measurement area is square,
The angle between the direction of the largest change in the color density distribution in the pixel of the color filter and one side of the square of the measurement area is 1
The measurement region is preferably set to be within 5 °, and desirably, the angle is set to 0 °, that is, parallel.

In the present invention, the ratio of the area of the measurement area and the shape of the measurement area are determined by the distribution direction and degree of the color density distribution, the shape of the pixel opening, and the color. What is necessary is just to select suitably considering the tolerance with respect to the measured value of a characteristic, the spectral wavelength resolution, the spectrometer specification, etc. In addition, a measure may be added such that the shape of the measurement area is rounded to the extent that it does not interfere with the corners, thereby preventing the diffraction phenomenon.

FIG. 1 schematically shows a cross section of an example of a color filter which is suitable as an object of the measuring method of the present invention and whose colored section is convex. In the figure, 1 is a colored portion, 2 is a light shielding portion, 3 is a glass substrate, and 4 is a protective layer. According to a general measuring method, the color characteristics of a color filter having a colored portion having a convex cross section as shown in FIG. 1 are measured by measuring a circular region as shown by 6 in FIG. I have. The measurement area 6 is circular because most of the spectrophotometer devices use pinholes or shutters.

When the colored portion 1 of the color filter shown in FIG. 1 is measured in a circular measurement area 6 having a small area as shown in FIG. 2, the characteristics of the color filter are as shown in FIG. This means that a part of the region with the highest concentration (measurement region A) is being measured. Therefore, although a chromaticity value with a high color purity is shown, it is clear that the color purity of the pixel itself of the color filter is low because there is a low-density region that is not actually measured. At this time, the area of the measurement region with respect to the pixel opening area is only about 10%.

As described above, the color density distribution of the color filter shown in FIG. 1 has a high color density at the center of the pixel and a lower color density around the light-shielding portion than at the center of the pixel as shown in FIG. . In the present invention, it is possible to measure the absolute color characteristic of the pixel of the color filter itself by setting the measurement region of the color characteristic so as to cover the color density distribution. In order to set the area so as to cover the color density distribution, the area ratio of the measurement area to the pixel opening may be set as large as possible. Therefore, in the color filter having the density distribution characteristic shown in FIG. 3, the absolute color characteristic of the pixel itself can be measured by measuring the entire colored density distribution of the measurement area as shown by the measurement area B in FIG. It will be good. As an example of the measurement area setting, an area indicated by 6 in FIG. 4 can be set. At this time, the area of the measurement region with respect to the pixel opening area is about 35%.

FIGS. 5 and 6 show the results when the color filter of FIG. 1 was measured by the general measuring method and the measuring method of the present invention, respectively. The broken line in FIG. 5 represents the spectral transmittance when measured in a circular measurement area according to a general measurement method, and the solid line is the spectral transmittance when measured in an area including the color density distribution according to the measurement method of the present invention. Represents FIG. 6 shows the difference on the xy chromaticity diagram between these two conditions. xy
The chromaticity diagram is based on a 2 ° viewing angle equation function under a standard C light source based on the CIE1931 color system.

In the above measurement example, a color filter in which the coloring density distribution in the pixel is convex has been described as an example, but the same concept can be applied to a color filter in which the color density distribution is concave. In particular, the difference in the coloring density in the pixel is 5% between the central part and the peripheral part.
When this is the case, the present invention is more effective. Also,
The same applies to a color filter having an uneven color density distribution in which the convex shape and the concave shape are intricately combined.

The method of creating the shape of the measurement area that covers the color density distribution in the pixel differs depending on the spectrometer, so if the measurement area is set according to the apparatus actually used for the measurement. Good.

According to the color characteristic measuring apparatus of the present invention, the shape of the stop is defined as a shape similar to the shape of the pixel opening, a shape having a curvature at the corner, or a square or a shape having a curvature at the corner. It is characterized by having done. In the device of the present invention,
The portion other than the measurement region is not particularly limited, and may be any device having a general optical system.

[0034]

EXAMPLES Example 1 An example in which a chromaticity value of a color filter was measured by setting a rectangular measurement area using a microspectrophotometer “MHL-525MS + OSP-SP200” manufactured by Olympus Corporation. Show. FIG. 7 shows a part of an optical system of the microspectrophotometer. In the figure, 8 is a light source for measurement, 9 is an aperture, 10 is a beam splitter, 11 is a condenser lens, 12 is a sample, 13 is an objective lens, 14
Is a diaphragm, 15 is a diffraction grating, 16 is a mirror, 17 is a line sensor, and 18 is a spectral unit.

In the microspectrophotometer, the light emitted from the measuring light source 8 is stopped down by the stop 9 and the optical axis is changed to the sample direction by the beam splitter 10. Spectroscopic unit (OSP
-SMU) 18, passes through the stop 14 at the entrance of the spectroscopic unit 18, is separated by the diffraction grating 15, and the separated light is measured by the line sensor 17 for measuring the light intensity.

FIG. 8 shows the appearance of the spectroscopy unit 18. In this example, a unit 20 in which the shape of the diaphragm is square without using the pinhole unit (OSP-TUR) 19 attached to the diaphragm 14 at the entrance of the spectroscopic unit 18 (FIG. 9)
Was prepared and used. The unit 20 having the square shape of the manufactured aperture 21 is made of a 3 mm-thick super-hard material, the aperture portion is a square hole of 1.5 mm square, and the thickness of this portion is 0.3 mm. processed. When the objective lens 13 of the microspectrophotometer is 20 times, the aperture width of the pixel portion of the sample 12 is 75 mm.
It is consistent with μm square. FIG. 4 shows a measurement region when the above setting is made. Under the conditions, the color filter having a convex cross section shown in FIG.
The xy chromaticity values at a 2 ° viewing angle under a standard C light source based on the 931 color system are as follows: R: x = 0.57, y = 0.33 G: x = 0.31, y = 0.53 B : X = 0.14, y = 0.15.

(Comparative Example 1) In Example 1, instead of using the unit 20 having a rectangular aperture shape, an attached pinhole unit (OSP-TUR) 19 was used so that the measurement area became φ = 25 μm. Set. FIG. 2 shows the measurement area of the color filter of FIG. 1 when set in this manner. As a result of measuring the same color filter as in Example 1 under these conditions, the measurement was performed under a standard C light source based on the CIE1931 color system. The xy chromaticity values at a 2 ° viewing angle are as follows: R: x = 0.60, y = 0.33 G: x = 0.31, y = 0.56 B: x = 0.14, y = 0.14 It became.

(Comparative Example 2) A color filter having a cross-sectional structure of a general color filter as shown in FIG. 10 and having a substantially constant coloring density distribution in a pixel was manufactured under the same measurement conditions as in Comparative Example 1. It was prepared by a pigment dispersion method so as to have the same chromaticity value as 1.

After a color liquid crystal display device was manufactured using the color filters measured in Example 1 and Comparative Example 1 and the color filter manufactured in Comparative Example 2, respectively, a color luminance meter BM-5A manufactured by Topcon Corporation was used. As a result of comparing chromaticity,
It was confirmed that the two color liquid crystal display devices had substantially the same xy chromaticity. From this, when measuring the color characteristics of a color filter having a color density distribution in a pixel,
Measurement conditions that depend on the size of the pinhole are not preferable, and it has been clarified that accurate color characteristics can be measured by measuring in a measurement region covering the color density distribution.

[0040]

As described above, according to the present invention,
Even with a color filter having a color density distribution in a pixel, an accurate chromaticity value comparable to that of a uniform color filter without a color density distribution in a pixel can be obtained, and a cross section is intentionally obtained. It is possible to accurately evaluate a color filter having a convex or concave shape and having a functional role.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a color filter having a convex cross-sectional shape, which is a preferable measurement target of the present invention.

FIG. 2 is a schematic plan view showing an example of a measurement area in a general measurement method.

FIG. 3 is a diagram showing a coloring density distribution of the color filter shown in FIG. 1;

FIG. 4 is a schematic plan view showing an example of a measurement region in the present invention.

5 is a diagram showing spectral transmittances when the color filter of FIG. 1 is measured by a general measuring method and a measuring method of the present invention, respectively.

FIG. 6 is a diagram showing differences on an xy chromaticity diagram when the color filter of FIG. 1 is measured by a general measuring method and a measuring method of the present invention, respectively.

FIG. 7 is a schematic diagram showing an optical system of a microspectrophotometer used in an example of the present invention.

FIG. 8 is a diagram showing an appearance of a spectroscopic unit of the microspectrophotometer used in the embodiment of the present invention.

FIG. 9 is a view showing an aperture unit having a square aperture used in the embodiment of the present invention.

FIG. 10 is a schematic cross-sectional view of a general color filter manufactured in Comparative Example 2 of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 colored portion 2 light-shielding portion 3 glass substrate 4 protective layer 5 pixel opening 6, 7 measurement region 8 measurement light source 9 aperture 10 beam splitter 11 condenser lens 12 sample 13 objective lens 14 aperture 15 diffraction grating 16 mirror 17 line sensor 18 spectral Unit 19 Pinhole unit 20 Square aperture unit 21 Square shape aperture

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Yoshihisa Yamashita, Inventor 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Akio Kashiwazaki 3- 30-2, Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Masafumi Hirose 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Ken Miyazaki 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (8)

[Claims] 1. A method for measuring a color characteristic of a color filter by measuring a spectral spectrum of a colored region, wherein a ratio of an area of the measurement region to an area of a pixel opening is 30% to 100%. A method for measuring the color characteristics of a characteristic color filter. 2. The method according to claim 1, wherein the measurement area has a shape similar to the shape of the pixel opening. 3. The method for measuring color characteristics of a color filter according to claim 1, wherein the measurement area has a shape in which a corner similar to the shape of a pixel opening has a curvature. 4. The method for measuring color characteristics of a color filter according to claim 1, wherein the measurement area is rectangular. 5. The method for measuring color characteristics of a color filter according to claim 1, wherein the measurement area has a shape in which a corner of a quadrangle has a curvature. 6. The color characteristic of the color filter according to claim 5, wherein the angle between the direction in which the color density distribution in the pixel of the color filter has the largest change and one side of the square of the measurement area is within 15 °. Measuring method. 7. The method for measuring color characteristics of a color filter according to claim 6, wherein the direction in which the color density distribution has the largest change is parallel to one side of the rectangle. 8. An apparatus for measuring color characteristics of a colored region of a color filter, wherein the shape of the stop is similar to the shape of a pixel opening, a shape in which a corner of the similar shape has a curvature, a square, An apparatus for measuring the color characteristics of a color filter, wherein the corners of a quadrangle have a curvature.