JPH08297204A - Color filter and color liquid crystal display device - Google Patents

Abstract

PURPOSE: To obtain such a color filter that white light entering perpendicular to the filter is changed into specified monochromatic light which is emitted from the filter perpendicular to the filter. CONSTITUTION: The color filter 10 is produced by laminating a transmission-type first hologram 14 and a second hologram 16 on both sides of a glass substrate 12. These holograms are laminated in such a manner that the pitch of a micro diffraction grating group 14R, 14G, 14B in the first hologram 14 is displaced by 1/2 of the color period from the pitch of a micro diffraction grating group 16R, 16G, 16B in the second hologram 16 and that the first order diffracted light beam of a specified color from the first hologram 14 enters the corresponding micro diffraction grating of the second hologram 16 and outgoes perpendicular to the grating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter using a diffraction grating, and more particularly to an apparatus in which a filter for transmitting a plurality of reference colors needs to be regularly patterned in a fine cell unit such as a color liquid crystal display. And a color liquid crystal display device using the same.

[0002]

2. Description of the Related Art A color liquid crystal display device using a filter as described above holds liquid crystal between two substrates having display electrodes, for example, one substrate side for color display corresponding to display pixels. The color display is performed by controlling the voltage between the counter electrodes and selectively changing the light transmission amount of the display unit.

[0003]

In the liquid crystal display device using the color filter for color display as described above,
The light transmittance of the color filter is about ⅙, and even an ideal optical system has a limit of ⅓, and there is a problem that the light utilization efficiency is low, that is, the screen becomes dark.

Further, a liquid crystal display device having a color filter has a problem that productivity is low and a yield is low, and especially when the size of the liquid crystal screen is large, it is difficult to manufacture and the cost is high. .

Further, the color filter used in the liquid crystal display device as described above is not a filter which transmits only a desired single color but a so-called bandpass filter, and its color separation ability is not always sufficient. .

The present invention has been made in view of the above-mentioned conventional problems, and when it is used in, for example, a color liquid crystal display device, the utilization efficiency of illumination light is high, therefore the screen is bright, and the productivity and yield are high. And a color filter capable of easily manufacturing even a large-sized screen at low cost and outputting a single color suitable for color separation input of CCD, and the like. An object is to provide a color liquid crystal display device using the same.

[0007]

According to the present invention, at least one kind of minute diffraction gratings are arranged in a direction orthogonal to the lattice stripes to form one color period, and a plurality of sets are regularly arranged in the direction orthogonal to the lattice stripes. Each of the minute diffraction gratings is a first transmissive diffraction grating having a pattern for emitting first-order diffracted light of a predetermined color when white light incident perpendicularly to the grating surface is transmitted. A medium and a minute diffraction grating patterned in the same type and order as in the first transmission type diffraction grating medium, and separated in parallel with the diffracted light output side of the first transmission type diffraction grating medium. Then, each set of the minute diffraction grating emits light from the minute diffraction grating of the first transmission type diffraction grating medium to the pair of the minute diffraction gratings of the opposing first transmission type diffraction grating medium. Origami is the first Second transmission diffraction grating arranged so as to be incident on a minute diffraction grating having the same pattern in the transmission diffraction grating medium at an angle equal to the diffraction angle of the first-order diffracted light, in a direction orthogonal to the grating stripes. A medium, and when the white light is perpendicularly incident on the first transmission type diffraction grating medium, the light of the predetermined color is emitted from the second transmission type diffraction grating medium. The above object is achieved by a color filter characterized by the above.

In the invention of claim 2, at least one kind of minute diffraction grating is arranged in a direction orthogonal to the grating stripes to form one color period, and a plurality of sets are regularly arranged in the direction orthogonal to the grating stripes. Each of the micro-diffraction gratings is patterned to emit a first-order diffracted light of a predetermined color when white light incident perpendicularly to the grating surface is transmitted, and has the same width as the micro-diffraction grating. And a first reflection type diffraction grating medium formed by patterning through holes arranged to transmit vertically incident light between the respective minute diffraction gratings,
The first reflection type diffraction grating medium is composed of a minute diffraction grating and a through hole which are patterned in the same type and rule, and the minute diffraction grating is opposed to the minute reflection grating of the first reflection type diffraction grating medium. Of the first diffraction grating medium of the first reflection type diffraction grating medium facing each other, and the first diffraction grating medium of the first transmission type diffraction grating medium, The first-order diffracted light reflected from the minute diffraction grating is orthogonal to the grating fringes so that the first-order diffracted light is incident on the minute diffraction grating of the same pattern in the second reflection-type diffraction grating medium at an angle equal to the diffraction angle of the first-order diffracted light. A second reflection-type diffraction grating medium arranged so as to be displaced in a direction, and the light of the predetermined color is emitted from the second reflection-type diffraction grating medium. Color fill Accordingly, it is intended to achieve the above object.

According to a third aspect of the present invention, in the second aspect, the through holes of the first and second reflection type diffraction grating media are capable of transmitting light and have a surface on which a minute diffraction grating is not formed. It was done.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the minute amount in the diffraction grating medium is corrected so as to correct a color shift due to a change in viewing angle from the front of the diffraction grating medium. The grating pitch of the minute diffraction grating on the central side in the direction orthogonal to the diffraction grating is made larger than the grating pitch of the minute diffraction grating at the end in the orthogonal direction according to the distance from the end.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the minute amount in the diffraction grating medium is corrected so as to correct the luminance change due to the change in the viewing angle from the front of the diffraction grating medium. The area of the minute diffraction grating in the central portion in the direction parallel to the diffraction grating is made smaller according to the distance from the end than in the end in the parallel direction.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the fine diffraction grating is patterned into three or more types so as to form first-order diffracted light of at least three colors. .

According to a seventh aspect of the present invention, in any one of the first to sixth aspects of the present invention, the first and second transmissive or reflective diffraction grating media are provided on both surfaces of one transparent parallel flat glass. It is a thing.

According to an eighth aspect of the present invention, in any one of the first to sixth aspects of the present invention, the first and second transmissive or reflective diffraction grating media are arranged via a space.

According to a ninth aspect of the present invention, in the invention according to any one of the first to eighth aspects, the diffraction grating medium is composed of an embossed film in which a minute diffraction grating is duplicated by an embossing method.

According to a tenth aspect of the present invention, liquid crystal is held between two substrates provided with display electrodes for each display pixel, and diffracted light of a color to be displayed by each display pixel is emitted outside one substrate. A color filter according to any one of claims 1 to 9 is provided,
The above-mentioned object is achieved by a color liquid crystal display device characterized by performing color display by controlling the voltage between the opposed electrodes to selectively change the light transmission amount of the illumination light in the display section.

[0017]

According to the first aspect of the present invention, the white light which is vertically incident on the first transmission type diffraction grating becomes a first-order diffracted light of a predetermined wavelength component when it is transmitted therethrough, and the white light has a diffraction angle of ± θ of 2
In order to be incident on the minute diffraction gratings of the same pitch in the corresponding second transmission type diffraction grating medium at the same angle, the light is vertically emitted from the second transmission type diffraction grating medium as first-order diffracted light. Go.

The light of another wavelength component that has passed through the first transmission type diffraction grating medium is incident on the minute diffraction grating of the second transmission type diffraction grating medium having a different grating pitch, so that it is converted into the first-order diffracted light from here. I can't emit light.

Further, since the first-order diffracted light which is incident on the minute diffraction grating of the second transmission type diffraction grating medium at a predetermined angle θ has a single wavelength, it is always emitted vertically from the second transmission type diffraction grating medium.

Further, the light emitted from the minute diffraction grating in the first transmission type diffraction grating medium and wrapping around to the uncorresponding minute diffraction grating in the second transmission type diffraction grating medium,
Since the wavelength and the incident angle are different, it is impossible to emit light from the minute diffraction grating in the second transmission type diffraction grating medium. Therefore, the desired single wavelength light is vertically emitted from the second transmission type diffraction grating medium.

According to the second aspect of the present invention, the light passing through the through hole of the second reflection type diffraction grating medium is vertically incident on the first reflection type diffraction grating medium, and the desired wavelength is obtained by each minute diffraction grating. The first-order diffracted light of the component is reflected in the direction of the second reflective diffraction grating medium at a diffraction angle of ± θ. The first-order diffracted light is incident on the corresponding minute diffraction grating of the same pitch in the second reflection-type diffraction grating medium, where it is vertically reflected as the first-order diffracted light and passes through the through-hole in the first diffraction grating to be vertically reflected. Light out.

The first-order diffracted light having another wavelength component from the first reflection-type diffraction grating medium is incident on a minute diffraction grating having a different grating pitch in the first reflection-type diffraction grating medium, or
Alternatively, since it enters the through hole, it cannot rise in the direction of the through hole in the first reflection type diffraction grating medium.

Since the first-order diffracted light incident on the second reflection type diffraction grating medium at a predetermined angle has a single wavelength, it does not emerge at an angle other than perpendicular to the through hole direction of the first minute diffraction grating. Therefore, the light emitted from the through hole of the first minute diffraction grating has a desired single wavelength component and is emitted vertically.

According to the third aspect of the present invention, the color filter can be easily and accurately formed by forming the through holes of the first and second reflection type diffraction grating media as the surfaces on which the minute diffraction grating which can transmit light is formed. Can be configured to.

According to the invention of claim 4, the grating pitch of the minute diffraction grating on the central side in the direction orthogonal to the minute diffraction grating in each diffraction grating medium is set to the grating of the minute diffraction grating at the end in the orthogonal direction. By making the pitch larger than the pitch in accordance with the distance from the edge, it is possible to correct the color shift due to the change in the viewing angle from the front surface of the diffraction grating medium.

Further, according to the invention of claim 5, in each diffraction grating medium, the area of the fine diffraction grating at the central portion in the direction parallel to the fine diffraction grating is set to be closer to the end portion than to the end portion in the parallel direction. By making it smaller according to the distance, it is possible to correct the change in luminance due to the change in the viewing angle from the front of the diffraction grating medium.

Further, according to the invention of claim 6, by patterning the minute diffraction grating in each of the diffraction grating media into three or more types so as to form at least three-color first-order diffracted light, for example, a color When used in a liquid crystal display device, accurate color display can be obtained.

According to the invention of claim 7, the color filter can be easily and easily formed by forming the first and second diffraction grating media as described above on both surfaces of one transparent parallel plate glass substrate. Can be configured accurately.

According to the invention of claim 8, the first, second
The weight of the color filter can be reduced by arranging the diffraction grating medium in parallel with each other through a space without using a glass substrate or the like.

According to the ninth aspect of the present invention, by forming the diffraction grating medium from an embossed film duplicated by an embossing method, a color filter can be formed easily, accurately and at low cost.

Further, according to the invention of claim 10, since the color filter composed of the first and second diffraction grating media as described above is provided as the color display means, the illumination light is not significantly attenuated, Diffracted light of a predetermined color is emitted to the display unit. Therefore, the screen is significantly brightened, and the diffracted light is monochromatic light, so that the color purity is high and vivid color display is performed.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, a color filter 10 made of a transmission type two-layer diffraction grating medium according to a first embodiment of the present invention comprises a transparent parallel plate glass substrate 12.
First hologram 1 which is a transmission type diffraction grating medium on both sides of
4 and the second hologram 16 are attached.

This diffraction grating medium can be obtained by drawing a diffraction grating pattern on a predetermined medium by using an electron beam on a resin sheet such as vinyl chloride as disclosed in JP-A-6-337315. It is obtained by pressing using a diffraction grating original plate.

However, since the diffraction grating medium of the present application is generally called a hologram, the term hologram will be used in the embodiments described below.

The first and second holograms 14 and 16
Is a three-dimensionally embossed transparent embossed hologram film 15, as shown in FIG.

The transmission type embossed hologram or the reflection type embossed hologram described later (see FIG. 3B) corresponds to the diffraction grating medium, but the resin sheet such as vinyl chloride is not always embossed. Instead of using a sheet, the glass substrate 12 may be directly etched to form a diffraction grating. However, the embossing method is preferable in terms of cost.

The first hologram 14 is patterned with different characteristics so that the first-order diffracted light having the diffraction angle θ when the light incident perpendicularly to the lattice plane is transmitted becomes the three primary colors of R, G and B, respectively. Each of the minute diffraction gratings 14R, 14G, and 14B having a width W is regularly arranged on the illumination light incident side (lower side in FIG. 1) in the RGB order in the direction perpendicular to the lattice stripes. Side (upper side in FIG. 1)
The second hologram 16 also has minute diffraction gratings 16R, 16G, and 16B arranged in the same pattern as the first hologram 14, and between the first and second holograms 14 and 16, the RGB cycle (in the direction orthogonal to the lattice stripes). The color period is arranged so as to be shifted by a half of the width of the minute diffraction grating W × 3), that is, 3W / 2.

When the distance between the first hologram 14 and the second hologram 16 in the thickness direction of the glass substrate 12 is D, the wavelengths of the first-order diffracted light in the minute diffraction gratings R, G and B are λ _R and λ. _G , λ _B , the grating pitch of the minute diffraction grating is P
_{Letting R} , P _G , P _B and the diffraction angle in the glass substrate 12 be θ, the following equation is established between them.

Sin θ = λ _R / P _R = λ _G / P _G = λ _B / P _B (1) tan θ = 3W / 2D (2)

The amount of deviation between the first and second holograms 14 and 16 in the direction orthogonal to the lattice fringes is n · 3W / 2 (n
May be a natural number). Further, since the diffraction angle is a refractive index n> 1 of the glass substrate 12, the real value is different from that in air, but the diffraction angle θ in the present invention is θ regardless of the refractive index of the substance through which the diffracted light passes. Shall be represented.

Next, the color filter 10 according to the above embodiment.
The operation of will be described.

In FIG. 1, the lower side, that is, the first hologram 1
When white light is vertically radiated from the outside of 4, the white light is reflected by the minute diffraction gratings 14R, 14G, 1 of the first hologram 14.
The light is diffracted in each of 4B, and the first-order diffracted light is emitted into the glass substrate 12 at a diffraction angle θ.

In the transmissive embossed hologram, as shown in an enlarged view in FIG. 3A, light is transmitted through the convex portion 15 A of the embossed hologram film 15 and the concave portion 15 is formed.
In B, scattering occurs and transmitted light is diffracted. Note that the unevenness on the glass substrate may be opposite to that in FIG.

First, the minute diffraction gratings 14R, 14G, 14B
The 1st-order diffracted light emitted from the light is split into two directions at a diffraction angle of ± θ with respect to the vertical line, and the corresponding minute diffraction gratings 16R, 16 of the second hologram 16 located at a position shifted by 3W / 2.
Since it is incident on G and 16B at an angle of ± θ, the incident wavelength λ
The lights of _R , λ _G , and λ _B are vertically diffracted and emitted from the respective minute diffraction gratings 16R, 16G, 16B of the second hologram 16.

Therefore, the light is vertically incident on the color filter 10.
The white light has a predetermined wavelength λ_R, Λ _G, Λ_BDivided into light
Light is emitted vertically from the second hologram 16.
It

Light of other wavelength components emitted from the first hologram 14 into the glass substrate 12 is incident on the minute diffraction gratings of the second hologram 16 having different pitches at the angle θ. It cannot be emitted as a break light. Therefore, the second hologram 16
Does not emit light other than the desired wavelength component.

Further, the second hologram 16 has a predetermined angle θ.
Since the first-order diffracted light that has entered at 1 is a single wavelength of R, G, or B, it cannot be emitted from the second hologram 16 at an angle other than vertical.

Furthermore, as shown in FIG. 4, for example,
From the minute diffraction grating 14R of one hologram 14 to the second holog
The light that has entered the minute diffraction grating 16G of the ram 16 has a wavelength
Is λ _RFrom λ_GThe angle of incidence is greater than θ
The small diffraction grating of the second hologram 16 is also small
I can't emit light through 16G.

In this embodiment, since the vertically incident white light can be used, a backlight structure similar to that of the color filter in the conventional color liquid crystal display device can be obtained. There is no need to use oblique parallel light.

Further, as described above, the first hologram 14
The wraparound light from the minute diffraction grating is prevented from entering the minute diffraction grating of the second hologram 16 to which it does not correspond, and the light is emitted from there, so that vivid color display can be performed.

Furthermore, since the diffracted light from the two corresponding minute diffraction gratings of the first hologram is incident on each of the minute diffraction gratings of the second hologram 16 from two directions, when the aperture area is doubled. You can get the same brightness as.

Further, since the light emitted from the color filter 10 has a single wavelength, it is possible to obtain light of a sharp color as compared with the conventional color filter which is substantially a bandpass filter.

In particular, when the color filter of this embodiment is used in a color liquid crystal display device, the following effects are obtained.
First, color display can be performed without using a color filter. Further, since the light is not attenuated by the color filter, it is possible to significantly improve the brightness on the screen of the liquid crystal panel and reduce the power consumption of the backlight.

Further, in terms of manufacturing cost, an embossed hologram can be manufactured for several hundred yen for a liquid crystal panel having a color filter size of about 10,000 yen conventionally.

Further, in the case of a liquid crystal panel using a color filter, when the color filter is defective, it has a great influence on optical characteristics such as color unevenness, so that the yield in the manufacturing process is low, but in the case of an embossed hologram. Even if some defects such as flaws do not affect the optical characteristics, the yield in the manufacturing process is extremely good. Also, conventional color C
In the case of a shadow mask in RT, convergence color shift is likely to occur, but in the case of this embodiment, since the color filter is replaced with an embossed hologram, color shift does not occur as in the color filter system. .

Next, a second embodiment of the present invention shown in FIG. 5 will be described.

The color filter 20 according to the second embodiment.
Is a structure in which a first hologram 24 and a second hologram 26, which are reflection type diffraction grating media, are attached to both surfaces of a transparent parallel plate-shaped glass substrate 22, respectively.

The first hologram 2 in the second embodiment
4, the second hologram 26 has the second hologram 26 on the light incident side and the first hologram 24 on the light outgoing side, contrary to the first embodiment.

Further, the first and second holograms 24, 26
Is provided with minute diffraction gratings 24R, 24G, 24B, 26R, 26G, and 26B of three primary colors of RGB arranged regularly, and both have the same pattern. Through holes 28 having the same width are regularly arranged. Therefore, the first and second holograms 2
The RGB cycle (color cycle) in the directions orthogonal to the grating stripes in Nos. 4 and 26 is 6W, which is the width W × 3 of the three-color minute diffraction gratings plus the width W × 3 of the three through holes 28. Corresponding first and second holograms 24, 26 in
The amount of deviation between the minute diffraction gratings is 6 W / 2 = 3 W.

These first and second holograms 24 and 26
As shown in an enlarged view in FIG. 3B, embossing is performed on the transparent synthetic resin embossed hologram film 15 on which the reflection film 15C made of aluminum is provided on the surface on the glass substrate 22 side. And the through hole 28 is a transparent synthetic resin layer on which the reflection film 15C is not formed and which is not embossed.

The distance D between the first and second holograms 24 and 26 and the wavelength λ of the first-order diffracted light in the second embodiment.
_R , λ _G , λ _B , pitches of minute diffraction gratings P _R , P _G , P
_B is set so that the equation (1) and the following equation (3) are established.

Tan θ = 6W / 2D (3)

Also in this embodiment, the amount of deviation between the first and second holograms 24 and 26 in the direction orthogonal to the lattice stripes is
It may be 3 W × n.

Next, the operation of the second embodiment will be described.

First, the vertically incident light from the white light source (not shown) arranged at the lower position in FIG. 4 passes through the through hole 28 of the second hologram 26 and the first hologram 24.
The light is vertically incident on the minute diffraction gratings 24R, 24G, and 24B, and is diffracted in the glass substrate 22 downward in the figure and in the direction of the second hologram 26 at an angle of ± θ. The wavelength components of this diffracted light are the desired λ _R , λ _G , and λ _B.

In the reflection type embossed hologram, as shown in FIG.
The illumination light incident from above in (B) is reflected by the concave portion 15D, and scattered by the convex portion 15E, and the reflected light is diffracted.

The diffracted light is incident on the minute diffraction gratings 26R, 26G and 26B of the corresponding second hologram 26 arranged with a shift of 6 W / 2 at an angle of ± θ, and
The minute diffraction gratings 26R and 26 of the second hologram 26
The wavelengths λ _R , λ _G , and λ _B lights incident on G and 26B are vertically diffracted here, and pass through the through holes 28 of the first hologram 24 to be emitted upward in FIG.

Also in the second embodiment, the first-order diffracted light having another wavelength component from the first hologram 24 is incident on the minute diffraction grating of the second hologram 26 having a different pitch or enters the through hole 28. Is either
It cannot rise in the direction of the through hole 28 of the first hologram 24.

Further, since the first-order diffracted light incident on the second hologram at a predetermined angle ± θ has a single wavelength, it cannot be emitted at an angle other than perpendicular to the through hole 28 direction of the first hologram. Therefore, the white light vertically incident on the color filter 20 from below must be the wavelength λ _R , λ _G, or λ _B.
The light is vertically emitted as light of three wavelengths.

The color filter 20 according to the second embodiment.
Has the same effect as the color filter 10 of the first embodiment, but has the following effect in addition to the case of the color filter of the first embodiment.

First, since it is not affected by the 0th-order diffracted light which is a straight traveling light, each color becomes clear and the contrast is improved. Next, as compared with the case of using the transmission type hologram as in the first embodiment, since the diffraction grating efficiency is high, its brightness is improved when used in the color liquid crystal display device.

Here, the opening area in the second embodiment is half that in the first embodiment, but the opening area is somewhat smaller due to the gap between the liquid crystal cells on the color liquid crystal side. Has no effect.

When the color filter according to the present invention is used in a color liquid crystal display device, the color shift becomes larger from the center toward the peripheral position of the screen due to the change of the viewing angle from the front of the liquid crystal screen.

To correct this, for example, as in the third embodiment shown in FIG. 6, the grating pitch of the minute diffraction grating 32 on the screen center side in the direction orthogonal to the grating of the minute diffraction grating in the diffraction grating medium 30. May be larger than the grating pitch of the minute diffraction grating at the end in the orthogonal direction according to the distance from the end.

Further, as in the fourth embodiment of the present invention shown in FIG. 7, the diffraction grating medium 3 is arranged so as to correct the brightness change (darker toward the periphery of the screen) due to the change in the viewing angle from the front.
The area of the micro-diffraction grating 36 in the central portion in the direction parallel to the grating of the micro-diffraction grating in 4 may be made smaller depending on the distance from the end than in the end in the parallel direction.

Further, the third and fourth embodiments may be combined to correct both the color shift and the luminance change due to the change of the viewing angle.

Next, an embodiment of a color liquid crystal display device using the color filter according to the present invention will be described with reference to FIG.

A color liquid crystal display device 40 according to this embodiment.
On the back side of the liquid crystal panel 42, a backlight 44 and a color filter 46 made of the above diffraction grating medium are arranged in combination.

Like the conventional liquid crystal panel, the liquid crystal panel 42 has a pair of opposing glass substrates 42A and 42B provided with transparent electrodes 42C and alignment films 42D and 42E, and a liquid crystal 42F held between them. Yes, glass substrate 42
Polarizing plates 42G and 42H are arranged outside the A and 42B, respectively.

The backlight 44 is composed of a point light source, a line light source or a surface light source which emits ordinary white light.

The minute diffraction grating of the above embodiment is RGB
However, the present invention is not limited to this, and other colors such as YMCK may be used, and when used as a monochromatic filter, only one type of minute diffraction grating is used. Become.

Furthermore, although the color filter according to the above-described embodiment is mainly used for a color liquid crystal display device, the color filter according to the present invention is not limited to this, and for example, a color filter such as CCD can be used. Those used for disassembly input, those used for single color filters, etc.
It can be generally used as a color filter.

[0084]

Since the present invention is configured as described above, it is possible to vertically emit the white light vertically incident on the filter as a single wavelength light having a desired wavelength. Therefore, it is a simple light source and bright and vivid. You can get colored light.

When the color filter according to the present invention is used in a color liquid crystal display device, diffracted light of a predetermined color is emitted to the display pixel without significantly attenuating the illumination light. Therefore, since the illumination light is less attenuated, the screen can be significantly brightened as compared with the case where the conventional color filter is used. Further, since the diffracted light of the color of each display pixel is monochromatic light, vivid color display can be performed.

Further, the color filter of the present invention is, for example, C
When used for color separation input of a CD, since the light passing through the color filter is a single color, the color separation ability can be greatly improved.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing a first embodiment of a color filter according to the present invention.

FIG. 2 is a schematic plan view showing a pattern of a minute diffraction grating of the same example.

FIG. 3 is an enlarged sectional view showing an embossed hologram used in the present invention.

FIG. 4 is an enlarged sectional view showing a part of the operation of the first embodiment.

FIG. 5 is a sectional view showing a color filter according to a second embodiment of the invention.

FIG. 6 is a schematic plan view showing a diffraction grating medium of a color filter according to a third embodiment of the invention.

FIG. 7 is a schematic plan view showing a diffraction grating medium of a color filter according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view showing an embodiment of a color liquid crystal display device using the color filter as a color display means.

[Explanation of symbols]

10, 20 ... Color filter 12, 22 ... Glass substrate 14, 24 ... First hologram 14R, 14G, 14B, 16R, 16G, 16B, 2
4R, 24G, 24B, 26R, 26G, 26B, 3
2, 36 ... Minute diffraction grating 16, 26 ... Second hologram 28 ... Through hole 30, 34 ... Diffraction grating medium 40 ... Color liquid crystal display device 42 ... Liquid crystal panel 44 ... Backlight 46 ... Color filter 42A, 42B ... Glass substrate 42C ... Transparent electrodes 42D, 42E ... Alignment film 42F ... Liquid crystal

Claims (10)

[Claims] 1. A set of at least one type of minute diffraction gratings arranged in a direction orthogonal to the grating stripes to form one color period, and a plurality of sets are regularly patterned in a direction orthogonal to the grating stripes. The minute diffraction grating has a pattern of a first transmission type diffraction grating medium which emits first-order diffracted light of a predetermined color when white light incident perpendicularly to the grating surface is transmitted, and the first transmission type diffraction grating medium. Microdiffraction grating, which is patterned in the same type and order as in the diffraction grating medium, is spaced apart in parallel with the diffracted light output side of the first transmission type diffraction grating medium, and is also a microdiffraction grating. The first-order diffracted light emitted from the minute diffraction grating in the first transmission type diffraction grating medium is the second transmission type In a diffraction grating medium A second transmission type diffraction grating medium arranged in a direction orthogonal to the grating fringes so as to be incident on the minute diffraction grating having the same pattern at an angle equal to the diffraction angle of the first-order diffracted light. And when the white light is vertically incident on the first transmission type diffraction grating medium, the light of the predetermined color is emitted from the second transmission type diffraction grating medium. . 2. A set of at least one kind of minute diffraction gratings arranged in a direction orthogonal to the lattice stripes to form one color period, and a plurality of sets are regularly patterned in a direction orthogonal to the lattice stripes. The minute diffraction grating has a pattern that emits first-order diffracted light of a predetermined color when white light incident perpendicularly to the grating surface is transmitted, and transmits vertically incident light with the same width as the minute diffraction grating. A first reflection type diffraction grating medium formed by arranging through holes to be arranged between the respective fine diffraction gratings and patterned, and the fine diffraction patterned by the same type and rule as in the first reflection type diffraction grating medium. The minute diffraction grating is composed of a grating and a through hole, and the minute diffraction grating faces the minute diffraction grating of the first reflection type diffraction grating medium and is spaced apart in parallel. The first-order diffracted light reflected from the minute diffraction grating in the first transmissive diffraction grating medium is the second reflective diffraction grating with respect to the pair of the minute diffraction gratings in the first reflective diffraction grating medium facing each other. A second reflection type diffraction grating medium arranged so as to be incident on a minute diffraction grating having the same pattern in the medium at an angle equal to the diffraction angle of the first-order diffracted light, the second reflection type diffraction grating medium being displaced in a direction orthogonal to the grating fringes. Done,
A color filter characterized in that the light of the predetermined color is emitted from the second reflective diffraction grating medium. 3. The color according to claim 2, wherein the through holes of the first and second reflection type diffraction grating media are light transmissive and are surfaces on which minute diffraction gratings are not formed. filter. 4. The diffraction grating medium according to any one of claims 1 to 3, in a direction orthogonal to the minute diffraction grating in the diffraction grating medium so as to correct a color shift due to a change in viewing angle from the front side. A color filter characterized in that the grating pitch of the minute diffraction grating on the central side is made larger than the grating pitch of the minute diffraction grating at the end in the orthogonal direction according to the distance from the end. 5. The diffraction grating medium according to any one of claims 1 to 4, in a direction parallel to the minute diffraction grating in the diffraction grating medium, so as to correct a change in luminance due to a change in viewing angle from the front of the diffraction grating medium. A color filter characterized in that the area of the minute diffraction grating at the central portion is made smaller according to the distance from the end portion than at the end portion in the parallel direction. 6. The color filter according to claim 1, wherein the minute diffraction grating is patterned into three or more kinds so as to form first-order diffracted light of at least three colors. 7. The method according to claim 1, wherein the first and second transmissive or reflective diffractive grating media are provided on both sides of one transparent parallel flat glass. Color filter. 8. A color filter according to claim 1, wherein the first and second transmissive or reflective diffraction grating media are arranged with a space in between. 9. The color filter according to claim 1, wherein the diffraction grating medium comprises an embossed film in which a minute diffraction grating is duplicated by an embossing method. 10. A liquid crystal is held between two substrates provided with a display electrode for each display pixel, and diffracted light of a color to be displayed by each display pixel is emitted outside one substrate. A color liquid crystal display device, wherein any one of the above color filters is provided, and color display is performed by controlling the voltage between the counter electrodes to selectively change the light transmission amount of illumination light in the display section.