JP3380946B2 - Transmission type color display - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive color display device such as a liquid crystal panel incorporated in a projector. More specifically, it relates to a technique for improving light resistance of a color filter formed on a liquid crystal panel.

[0002]

2. Description of the Related Art FIG. 8 shows an example of a conventional projector. This projector includes a light source 101 along the optical axis direction,
Liquid crystal panel 102, projection lens 103, screen 10
4 are arranged in order. White light emitted from the light source 101 passes through a transmissive color display device including a liquid crystal panel 102 and the like, is enlarged and projected forward through a projection lens 103, and a color image is displayed on a screen 104. The transmissive color liquid crystal panel 102 is composed of a pair of transparent electrode substrates that are joined together with a predetermined gap therebetween to form pixels in a matrix. Liquid crystal is held in this gap as an electro-optical substance, and the transmittance changes for each pixel. A color filter is formed on one transparent electrode substrate. This color filter contains pigments of a plurality of coloring species selectively dispersed corresponding to pixels, and selectively colors light passing through each pixel into any of the three primary colors.

[0003]

By the way, in recent years, projectors are increasingly required to have the brightness of the projected screen (image brightness). Therefore, the output of the light source 101 is increased and the liquid crystal panel 102 is illuminated with strong white light. In addition, the liquid crystal panel 102 is combined with a microlens array to collect the light from the light source on each pixel to increase the brightness. In this case, a large amount of light rays are applied to the color filter, which causes deterioration of the pigment dispersed in the color filter. Generally, in a color filter, an organic pigment is used in order to obtain a desired chromaticity, and accordingly, the light resistance is insufficient. On the other hand, if an inorganic pigment that is more excellent in light resistance than an organic pigment is used, the chromaticity of the three primary colors required for a color filter cannot be obtained properly. For this reason, in the conventional projectors, strong light source light cannot be used in order to suppress the color filter deterioration and the image brightness is limited. Further, the light resistance of the color filter is generally closely related to the temperature.
That is, fading deterioration is accelerated as the ambient temperature rises. Therefore, in order to suppress heat generation due to absorption of light from the light source, it is necessary to incorporate a large-scale cooling device in the projector. It should be noted that a technique for achieving high brightness by adopting a three-plate type instead of the single-plate type using one transmissive color liquid crystal panel shown in FIG. 8 has been developed. This three-panel system uses three monochrome liquid crystal panels, each with a polarizing beam splitter (PBS).
And the like are used to illuminate the light source light that is split into the three primary colors.
However, the three-plate type projector has a large demerit such as a complicated optical system as compared with the single-plate type projector.

[0004]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, an object of the present invention is to improve the light resistance of color filters. The following measures have been taken in order to achieve this object. That is, the transmission type color display device according to the present invention has, as a basic configuration, a pair of transparent electrode substrates, an electro-optical material, and a color filter. The pair of transparent electrode substrates are bonded to each other with a predetermined gap therebetween to form a matrix of pixels. The electro-optical material is held in the gap and the transmittance changes for each pixel. The color filter contains pigments of a plurality of coloring species selectively dispersed corresponding to pixels, and selectively colors light passing through each pixel into any of the three primary colors. As a feature of the present invention, the color filter uses organic pigments for most of the coloring species having relatively good light resistance, and uses inorganic pigments only for some coloring species having poor light resistance. That is , the color filter uses an organic pigment as a main coloring species corresponding to the three primary colors having good light resistance, and only an inorganic pigment having poor light resistance among auxiliary coloring species added for chromaticity correction of the three primary colors is used. To use. Preferably, the transmissive color display device is an active matrix type. That is, one transparent electrode substrate has a continuous transparent electrode, and the other transparent electrode substrate has a transparent electrode separated for each pixel and a switching element for driving each transparent electrode. In this case, the color filter is formed on the other transparent electrode substrate in alignment with each transparent electrode. Further, preferably, the transmission color display device is provided with a microlens array, and collects incident light for each pixel and makes it enter the color filter.

[0005]

At present, since the color filter incorporated in the transmissive color display device uses an organic pigment, when it is applied to a projector or the like, it is irradiated with strong light from a light source and deteriorates in color. Further, since there are extremely few choices of coloring species using only inorganic pigments, the chromaticity of the color filter is poor and it cannot be used in practice. Therefore, in the present invention, at least one kind of inorganic pigment is mixed in place of the organic pigment having low light resistance, thereby improving the light resistance without lowering the chromaticity.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic sectional view showing a first embodiment of a transmissive color display device according to the present invention. This embodiment shows an active matrix type liquid crystal panel as a transmissive color display device. The present liquid crystal panel is formed using an upper transparent electrode substrate (counter substrate) 1 and a lower transparent electrode substrate (driving substrate) 2. Counter substrate 1
And the driving substrate 2 are joined to each other with a predetermined gap therebetween to form pixels in a matrix. Specifically, the counter substrate 1 is formed by continuously forming a transparent electrode (counter electrode) 4 on an inner surface of a glass base material 3. On the other hand, the drive substrate 2 is formed by arranging transparent electrodes (pixel electrodes) 6 in a matrix on the inner surface of the glass substrate 5. A pixel is defined between the counter electrode 4 and the pixel electrode 6. A liquid crystal 7 is held in the gap between the counter substrate 1 and the driving substrate 2 as an electro-optical substance,
The transmittance changes for each pixel. Further, a color filter 8 is formed on the drive substrate 2 side, contains pigments of a plurality of coloring species selectively dispersed corresponding to pixels, and selectively transmits light passing through each pixel in three primary colors (R , G, B). As a feature of the present invention, the pigment-dispersed color filter 8 uses organic pigments for most of the coloring species having relatively good light resistance, and uses inorganic pigments only for some coloring species having poor light resistance. I am using. For example, an organic pigment is used for the main coloring species corresponding to the three primary colors (R, G, B) having good light resistance, and one of the auxiliary coloring species added for the chromaticity correction of the three primary colors has poor light resistance ( For example Yel
An inorganic pigment is used only in (low). With this configuration,
The light resistance can be improved without substantially lowering the chromaticity of the color filter 8.

Continuing to refer to FIG. 1, a method of manufacturing an active matrix type liquid crystal panel will be briefly described. First, the thin film transistor 9 is integrally formed on the glass substrate 5. The thin film transistor 9 serves as a switching element for driving each pixel electrode 6. First, the glass substrate 5
Forming a semiconductor thin film 10 such as polycrystalline silicon on the surface of
The element region is patterned into a predetermined shape. A gate electrode G is patterned on the semiconductor thin film 10 via a gate insulating film. Impurities are injected into the semiconductor thin film 10 at a high concentration by self-alignment using the gate electrode G as a mask to form a source region and a drain region. Thereby, the top gate type thin film transistor 9 can be formed. The thin film transistor 9 is covered with a first interlayer insulating film 11 made of PSG or the like. A contact hole is opened in the first interlayer insulating film 11, and a metal film is formed thereon.
This metal film is patterned into a predetermined shape to provide a source electrode S connected to the source region of the thin film transistor 9 and a drain electrode D connected to the drain region. The source electrode S and the drain electrode D are covered with the second interlayer insulating film 12 also made of PSG or the like. Second interlayer insulating film 12
After opening a contact hole in the substrate, a metal film is formed, patterned into a predetermined shape, and processed into the black matrix 13. The black matrix 13 is electrically connected to the drain electrode D via the contact hole. Further, the pigment dispersion type color filter 8 is formed on the second interlayer insulating film 12. First, a photosensitive material (color resist) in which a pigment finely adjusted according to the chromaticity of R is dispersed is applied, exposed,
Develop and bake. Similarly, a color resist containing a pigment prepared according to the chromaticity of G is applied, and exposure, development and baking are performed. Further, a color resist containing a pigment prepared according to the chromaticity of B is applied, and exposure, development and baking are performed. In this way, the color filters 8 that are divided and arranged corresponding to each pixel are provided. The color filter 8 has a black matrix 13 for each of R, G, and B.
Separated by. A flattening film 14 made of acrylic resin or the like is applied so as to cover the color filter 8. After opening a contact hole in the flattening film 14, a transparent conductive film made of ITO or the like is formed and patterned into a predetermined shape to form the pixel electrode 6. Each pixel electrode 6 is provided with a thin film transistor 9 through a corresponding black matrix 13.
Is electrically connected to the drain electrode D. On the other hand, a transparent conductive film also made of ITO or the like is entirely formed on the surface of the upper glass substrate 3, and the counter electrode 4 is processed. The counter substrate 1 thus obtained and the drive substrate 2 previously obtained are bonded together with a predetermined gap. When the liquid crystal 7 is injected into this gap,
The active matrix type color liquid crystal panel is completed.

FIG. 2 is a schematic partial sectional view showing a second embodiment of the transmission type color display device according to the present invention. Basically, it is the same as the liquid crystal panel shown in FIG. 1, and corresponding parts are designated by corresponding reference numerals to facilitate understanding. The difference is that the microlens array 15 is formed on the counter substrate 1 side. The microlens array 15 is provided corresponding to each pixel electrode 6. Specifically, the microlens array 15 has a structure in which it is sandwiched between the upper glass substrate 3 and the lower glass substrate 16. For example, the microlens array 15 can be formed by forming a concave portion in the upper glass substrate 3 by etching and filling the concave portion with a resin having a high refractive index. Alternatively, the microlens array 15 may be formed by introducing impurity ions into the glass base material 3 in a lens shape to change the refractive index. The microlens array 15 collects incident light for each pixel and makes it enter the color filter 8. By doing this, the black matrix 13 is originally
The incident light that is blocked by can also be focused on the color filter 8, so that when incorporated in a projector or the like, the light source light can be used more efficiently. On the other hand, since the light intensity becomes high, fading deterioration of the pigment dispersed in the color filter 8 is promoted. In view of this point, in the present invention, the inorganic pigment is used only for the coloring species having particularly poor light resistance.

FIG. 3 is a schematic sectional view showing a third embodiment of the transmissive color display device according to the present invention, and shows a simple matrix type liquid crystal panel. This liquid crystal panel has an upper transparent electrode substrate 31 and a lower transparent electrode substrate 32.
It has a structure in which and are joined via a predetermined gap. The transparent electrode 33 is patterned on the inner surface of the upper transparent electrode substrate 31 along the row direction. The transparent electrodes 34 are patterned on the inner surface of the lower transparent electrode substrate 32 along the column direction. Transparent electrode 33 and transparent electrode 34
Pixels arranged in a matrix (matrix arrangement) are defined at the intersections of. A liquid crystal 35 is provided between the transparent electrode 33 and the transparent electrode 34.
Is held.

The upper transparent electrode substrate 31 is a glass base material 36.
Is formed by using. A black matrix 37 is patterned on the inner surface of the glass substrate 36. First, on the surface of the glass substrate 36, Cr, Ti, Al, W, M
a metal film having a light-shielding property such as o by sputtering or the like
It is possible to form a film with a thickness of 1000 nm, pattern it into a predetermined shape, and process it into the black matrix 37. Alternatively, instead of the metal film, a resin in which a black pigment or carbon is dispersed may be applied by spin coating to a thickness of 100 to 3000 nm and patterned into a predetermined shape. A color resist to be a colored layer is applied on the black matrix 37 with a film thickness of about 0.5 to 3.0 μm, and exposure, development and baking are performed three times for each of the RGB segments. To process. After that, for example, acrylic or styrene resin is applied in a thickness of 500 to 3000 nm to form a protective film 39. A transparent conductive film such as ITO having a thickness of 50 to 200 nm is formed on the protective film 39 by sputtering, and is patterned into stripes to form the transparent electrode 33. Here, the color resist used for the color filter 38 is a main coloring species (Red, Green, Blue) substantially corresponding to the three primary colors of RGB, and an auxiliary coloring species (Yellow, Vi) added for chromaticity correction of the three primary colors.
olet). Organic pigments are used for the main coloring species having good light resistance, and inorganic pigments are used only for auxiliary coloring species having poor light resistance (for example, Yellow). That is, the light resistance of the color filter 38 as a whole is improved by mineralizing only the minimum necessary amount of pigment, and a large deterioration in chromaticity is prevented.

FIG. 4 is a schematic partial sectional view showing a fourth embodiment of the transmissive color display device according to the present invention. Basically, it is similar to the third embodiment shown in FIG. 3, and corresponding parts are designated by corresponding reference numerals to facilitate understanding. However, in FIG. 4, only the upper transparent electrode substrate 31 is shown. The transparent electrode substrate 31 contains a microlens array 41, and collects incident light for each pixel R,
It enters the G and B color filters 38. The microlens array 41 is held by glass substrates 36 and 40 from above and below. The microlens array 41 is formed by applying an etching method or an ion substitution method to the glass base material 36.

FIG. 5 is a graph showing the spectral transmittance characteristics of the color filter. The horizontal axis shows wavelength (nm) and the vertical axis shows transmittance (%). The color filter is B of the three primary colors
The spectral characteristics include peaks corresponding to the component, the G component, and the R component. The peak wavelength of the B component is 470 nm and the peak transmittance is 73%. In order to obtain such a spectral characteristic, the color filter uses a mixed pigment of the main coloring species Blue and the chromaticity correction auxiliary coloring species Violet. The peak wavelength of the G component is 540 nm, and the peak transmittance is 68%. In order to obtain this spectral characteristic, the color filter uses a mixed pigment of the main coloring species Green and the auxiliary coloring species Yellow. The peak wavelength of the R component is 630 nm, and the peak transmittance is 91%. In order to obtain this spectral characteristic, the color filter uses a mixed pigment of the main coloring species Red and the auxiliary coloring species Yellow.

FIG. 6 is a graph showing the spectral characteristics of each individual colored species. In this example, as a coloring species Red, a dianthraquinone-based organic pigment R177 (Pigment No.
The same shall apply hereinafter). As the coloring species Green, a halogenated copper phthalocyanine type G36 is used. As the coloring species Blue, a copper phthalocyanine-based organic pigment B15: 6 is used. As the auxiliary coloring species Yellow, an isoindoline-based organic pigment Y139 has been conventionally used. For the remaining auxiliary coloring species Violet, a dioxazine-based organic pigment V23 is used.
As can be understood from the spectral characteristics of the individual colored species shown in FIG. 6, for example, the main colored species Red and the auxiliary colored species Yellow
By using the mixed pigment of w, a desired red chromaticity suitable for a color filter can be obtained. Similarly, by using a mixed pigment of the main coloring species Green and the auxiliary coloring species Yellow,
A desired green chromaticity suitable for the color filter can be obtained.
Further, by using a mixed pigment of the main coloring species Blue and the auxiliary coloring species Violet, a desired blue chromaticity suitable for a color filter can be obtained.

FIG. 7 is a graph showing the results of the light resistance test of the color filter obtained by blending the various coloring species shown in FIG. The changes with time of the R, G, and B chromaticities are shown on the xy chromaticity diagram of the CIE color system. The light fastness test was carried out while irradiating light of 5 million lux and keeping the color filter at 60 ° C. The conditions are based on actual use in the projector. Each RGB chromaticity is 0 hour, 24
It is measured every 0 hours, 500 hours, 1000 hours and 1500 hours and is plotted in the graph. As is clear from this graph, the fading deterioration of the G component is remarkable, and it changes in the direction of the B component on the chromaticity diagram. It is considered that this is because the organic pigment used for the auxiliary coloring species Yellow of the G component is extremely deteriorated. Therefore, in the present invention, as the auxiliary coloring species Yellow, an inorganic pigment is used instead of the conventional organic pigment. As this inorganic pigment,
For example, Ti-Sb-Ni-based oxide or Ti-Sb
A -Cr-based oxide can be used.

[0015]

As described above, according to the present invention, in the pigment-dispersed color filter, at least one inorganic pigment is mixed and used in place of a part of the organic pigment having particularly poor light resistance. The light resistance of the color filter as a whole can be improved without significantly degrading the chromaticity. As a result, when the color liquid crystal panel is incorporated in the projector, the panel cooling mechanism and the optical system can be simplified. As described above, a high-luminance, compact transmissive color display device can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a transmissive color display device according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of a transmissive color display device according to the present invention.

FIG. 3 is a sectional view showing a third embodiment of a transmissive color display device according to the present invention.

FIG. 4 is a partial sectional view showing a fourth embodiment of a transmissive color display device according to the present invention.

FIG. 5 is a graph showing a spectral transmittance characteristic of a color filter.

FIG. 6 is a graph showing spectral transmittance characteristics of individual pigments used for color filters.

FIG. 7 is a graph showing the light resistance test results of color filters.

FIG. 8 is a schematic diagram showing an example of a conventional projector.

[Explanation of symbols] 1 Counter substrate 2 drive board 3 glass base materials 4 Counter electrode 5 glass base materials 6 pixel electrodes 7 liquid crystal 8 color filters 9 thin film transistor 10 Semiconductor thin film 13 Black Matrix 14 Flattening film 15 Micro lens array

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuneo Kusunoki 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation (56) Reference JP-A-4-177203 (JP, A) JP-A 6-167704 (JP, A) JP 5-346578 (JP, A) JP 62-218902 (JP, A) JP 63-125902 (JP, A) JP 63-314501 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02F 1/1335 505 G02F 1/13 505 G09F 9/00

Claims (3)

(57) [Claims] 1. A pair of transparent electrode substrates which are bonded to each other through a predetermined gap to form a matrix of pixels, an electro-optic substance which is held in the gap and whose transmittance changes for each pixel, and a pixel corresponding to the pixel. And a color filter containing a plurality of colored pigments selectively dispersed therein and having a color filter that selectively colors light passing through each pixel into one of the three primary colors, wherein the color three primary filter having a relatively good with organic pigments for the majority of the colored species having light resistance, there is used an inorganic pigment only part of the colored species having poor lightfastness, good lightfastness About the main colored species corresponding to
As an organic pigment, it is added for chromaticity correction of the three primary colors
Use inorganic pigments only for auxiliary coloring species with poor light resistance
Transmissive color display device, characterized in that there. 2. One transparent electrode substrate has a continuous transparent electrode, the other transparent electrode substrate has a transparent electrode separated for each pixel, and a switching element for driving each transparent electrode, 2. The transmissive color display device according to claim 1, wherein the filter is aligned with each transparent electrode and formed on the other transparent electrode substrate. 3. The transmissive color display device according to claim 1, further comprising a microlens array that collects incident light for each pixel and makes it enter the color filter.