JPH09230320A - Liquid crystal display device formed by using hologram color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal display device which is good in color balance of three colors and is good in color reproducibility even if a fluorescent tube is used as a back light source. SOLUTION: This liquid crystal display device has liquid crystal display elements and hologram color filters which is disposed on the incident side of its illumination light 3, consist of arrays of element holograms 5' and spectral split incident white light 3 at an incident angle θ by wavelength dispersion of the holograms of the light in the direction approximately along the hologram recording surface. In such a case, the fluorescent tube which has at least one bright line peaks respectively in a recording region wavelength region, green wavelength region and blue wavelength region and in which the main bright line peak wavelengths of the red wavelength region and blue wavelength region exist approximately symmetrically around the main bright line peak wavelength in the green wavelength region as a center is used as the light source for the white line 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device using a hologram color filter, and more particularly, in a direct-viewing type liquid crystal display device using a fluorescent tube as a backlight source, color reproduction of three colors with good color balance. TECHNICAL FIELD The present invention relates to a liquid crystal display device using a hologram color filter in which the utilization efficiency of illumination light having good properties is significantly improved.

[0002]

2. Description of the Related Art Conventionally, in a color liquid crystal display device using an absorption color filter using a pigment, a dye or the like,
The backlight is indispensable for display.
However, if white light is simply irradiated from behind the color liquid crystal display device, its utilization efficiency is very low. The main reasons are as follows.

[0003] The area occupied by the black matrix other than the cells of each color is large, and the light hitting it is wasted. Among white light incident on each pixel, R (red), G (green),
Since the color components passing through the B (blue) color filter are limited, other complementary color components are wasted. There is a loss due to absorption in the color filter.

In order to solve such a problem, for example, a microlens array is installed in front of a color filter,
2. Description of the Related Art There has been conventionally known a method of increasing the utilization efficiency of a backlight by concentrating a backlight of white light on color filter cells R, G, and B, respectively.

[0005] However, even with this method, it is not possible to irradiate the white light 3 to each of the color filter cells R, G, B in a spectral manner, so that the above-mentioned problem cannot be solved.

Further, a liquid crystal projector in which the use efficiency of light is improved by using three dichroic mirrors and a microlens array without using such a color filter has been proposed in Japanese Patent Application Laid-Open No. Hei 4-60538. In this case, the above-mentioned absorption color filters using pigments, dyes and the like become unnecessary, and the above-mentioned problems (1) to (5) are solved, and the luminance of a color image is improved. However, since three dichroic mirrors are required, optical The system and equipment become large and bulky. In addition, there is a problem that the cost becomes high.

In view of such a situation, the present applicant has proposed in Japanese Patent Application No. 5-12170, etc. a color filter using a hologram and a color filter using the hologram in order to significantly improve the utilization efficiency of a liquid crystal display backlight or the like. We have proposed a liquid crystal display device using.

A liquid crystal display device using such a hologram color filter will be briefly described below. First, a liquid crystal display device using a first type hologram color filter will be described with reference to the sectional view of FIG. In the figure, a hologram array 5 constituting a color filter is arranged at a distance from the backlight 3 incident side of a liquid crystal display element 6 which is regularly divided into liquid crystal cells 6 '(pixels). On the back surface of the liquid crystal display element 6, a black matrix 4 provided between the liquid crystal cells 6 'is arranged. In addition to the above, polarizing plates (not shown) are arranged on the incident side of the hologram array 5 and on the exit side of the liquid crystal display element 6.
An absorption type color filter that transmits light of colors corresponding to the R, G and B color separation pixels is additionally arranged between the black matrixes 4 as in the conventional color liquid crystal display device. You may do it.

The hologram array 5 corresponds to a repeating period of R, G, and B color-separating pixels, that is, each set of three liquid crystal cells 6'adjacent to each other in the direction of the liquid crystal display element 6 in the plane of the drawing. It is composed of minute holograms 5'arranged in an array at the same pitch as the repeating pitch, and the minute holograms 5'are aligned in groups of three liquid crystal cells 6'adjacent to each other in the direction of the paper surface of the liquid crystal display element 6 to form one group. The micro holograms 5'are arranged one by one, and each micro hologram 5'corresponds to the micro hologram 5'the light of the green component in the backlight 3 which is incident at an angle θ with respect to the normal line of the hologram array 5. It is formed in a Fresnel zone plate shape so as to collect light on the liquid crystal cell G at the center of the three color-dividing pixels R, G, and B. The micro hologram 5 ′ has a relief type, which has no or little wavelength dependence of the diffraction efficiency.
It consists of transmission holograms such as phase type and amplitude type. Here, the term "diffraction efficiency has no or little wavelength dependency" does not mean that it is a type that diffracts only a specific wavelength and hardly diffracts other wavelengths like a Lippmann hologram. Is also diffracted, and the diffraction grating whose diffraction efficiency has little wavelength dependence diffracts at different diffraction angles depending on the wavelength.

With such a configuration, when the white backlight 3 which is incident at an angle θ with respect to the normal line from the surface of the hologram array 5 opposite to the liquid crystal display element 6 is incident, the wavelength is changed. The diffraction angles of the minute holograms 5'are different depending on the wavelengths, and the focusing positions for each wavelength are dispersed in the direction parallel to the surface of the hologram array 5. Among them, the red wavelength component is located at the position of the liquid crystal cell R displaying red, the green component is located at the position of the liquid crystal cell G displaying green, and the blue component is located at the position of the liquid crystal cell B displaying blue. By arranging the hologram array 5 so as to diffract and collect light, each color component passes through each liquid crystal cell 6 ′ with almost no attenuation in the black matrix 4 and the liquid crystal cell 6 ′ at the corresponding position. Color display can be performed according to the state. The angle of incidence θ of the backlight 3 on the hologram array 5 depends on the hologram recording conditions, hologram array 5
Of the hologram array 5, the distance between the hologram array 5 and the liquid crystal display element 6, and the like.

As described above, by using the hologram array 5 as a color filter, each wavelength component of the conventional color filter backlight can be made incident to each liquid crystal cell 6'without being absorbed, and its utilization efficiency is improved. Can be significantly improved.

Next, a liquid crystal display device using a second type hologram color filter will be described with reference to the sectional view of FIG. In the figure, the second type hologram color filter 10 comprises a hologram 7 and a condensing microlens array 8, and the microlenses 8'constituting the microlens array 8 are R, G, and B.
Repetition cycle of the color-separated pixels, that is, the liquid crystal display element 6
Corresponding to each set of three liquid crystal cells 6'adjacent to each other in the direction of the plane of the drawing, they are arranged in an array at the same pitch as the repeating pitch. The hologram 7 is composed of parallel and uniform interference fringes acting as a diffraction grating, and is formed of a transmission hologram such as a relief type, a phase type, and an amplitude type having little or no wavelength dependence of diffraction efficiency. On the back surface of the liquid crystal display element 6, a black matrix 4 provided between the liquid crystal cells 6 'is arranged. In addition to the above, polarizing plates (not shown) are arranged on both sides of the liquid crystal display element 6. In addition,
As in the conventional color liquid crystal display device, an absorption type color filter which transmits light of colors corresponding to the R, G and B color separation pixels is additionally arranged between the black matrixes 4. May be.

Due to such a configuration, the hologram 7
When the backlight 3 is incident on the surface opposite to the liquid crystal display element 6 at an angle θ with respect to the normal line, the light is diffracted at different angles depending on the wavelength and dispersed on the exit side of the hologram 7. . Due to the microlenses 8 ′ arranged on the incident side or the exit side of the hologram 7, this dispersed light
The light is separated and focused on the focal plane for each wavelength. Among them,
The red wavelength component is diffracted and focused on the position of the liquid crystal cell R displaying red, the green component is focused on the position of the liquid crystal cell G displaying green, and the blue component is focused on the position of the liquid crystal cell B displaying blue. By arranging the hologram color filter 10 as described above, each color component passes through each liquid crystal cell 6 ′ with almost no attenuation in the black matrix 4,
Color display can be performed according to the state of the liquid crystal cell 6'at the corresponding position.

In such an arrangement, as the hologram 7, it is possible to use, as the hologram 7, a transmission type hologram having uniform diffraction fringes and having a small wavelength dependence of diffraction efficiency. No need to be aligned with each microlens 8 ', and the pitch of the microlens array 8 depends on each liquid crystal cell 6'.
It is three times as large as the conventional case where one microlens is arranged corresponding to each, and is characterized in that it is easy to manufacture and easy to align.

In the liquid crystal display device using the hologram color filter as described above, the liquid crystal display element 6 including the black matrix 4 is actually, for example, as shown in FIG.
As shown in the cross section in FIG. 1, the liquid crystal display element 6 is composed of, for example, a liquid crystal layer 25 such as twisted nematic sandwiched between two glass substrates 21 and 22, and is formed on the inner surface of the glass substrate 21 on the backlight side. Is provided with a black matrix 4 and a uniform transparent counter electrode 23, and on the inner surface of the glass substrate 22 on the display surface side, a transparent pixel electrode 24 and a TFT (not shown) are provided independently for each liquid crystal cell R, G, B. Is provided. An alignment layer (not shown) is also provided on the liquid crystal layer 25 side of the electrodes 23 and 24. The hologram color filter 5 or 10 provided on the surface of the substrate 26 on the side of the liquid crystal display element 6 that is close to or bonded to the glass substrate 21 on the backlight side is arranged, and the polarizing plate 12 is provided on the backlight side of the substrate 26. Polarizing plates 13 are attached to the outer surface of the observation-side glass substrate 22 of the liquid crystal display element 6, for example, and their transmission axes are arranged so as to be orthogonal to each other. The polarizing plate 12 on the backlight side
Instead of sticking to the backlight side of the substrate 26,
As shown by the dotted line in FIG. 9, it may be arranged in the optical path of the backlight 3 away from the hologram color filter 5.

Color display is possible by controlling the voltage applied between the transparent pixel electrode 24 and the transparent counter electrode 23 for each pixel of the liquid crystal display element 6 to change the transmission state thereof. .

[0017]

By the way, in a liquid crystal display device using the hologram color filter as described above, particularly in a direct-viewing type liquid crystal display device, it is considered to use a three-wavelength fluorescent tube as a white backlight light source. To be

However, in a normal three-wavelength fluorescent tube,
The peak wavelengths of the bright lines are around 430 nm for blue (B), around 545 nm for green (G), and around 610 nm for red (R). Compared with the wavelength difference between R and G, B and G
Is large, and the wavelength dispersion angle due to the hologram color filter is largely different on the R side and the B side with G as the center, and it is difficult to make all of the above three bright lines incident on the respective RGB openings of the black matrix. Therefore, it is difficult to improve the color balance of color display, and there is a problem that sufficient color reproducibility cannot be obtained.

The present invention has been made in view of such problems of the prior art, and an object thereof is to achieve good color reproducibility and good color balance of three colors even if a fluorescent tube is used as a backlight light source. An object of the present invention is to provide a liquid crystal display device using a good bright hologram color filter.

[0020]

A liquid crystal display device using a hologram color filter of the present invention that achieves the above-mentioned object is provided with at least a liquid crystal display element and an illumination light incident side thereof, and is provided with an element condensing hologram. A hologram color filter consisting of an array, in which each element condensing hologram disperses white light incident at a predetermined angle with respect to the normal line of the hologram recording surface by wavelength dispersion in a direction substantially along the hologram recording surface. , Or a hologram or diffraction grating consisting of parallel and uniform interference fringes and an array of element condensing lenses arranged on the incident side or the exit side thereof,
The hologram or diffraction grating consisting of parallel and uniform interference fringes and the complex of the element condensing lens respectively emit white light incident at a predetermined angle with respect to the normal to the recording surface of the hologram or diffraction grating. In a liquid crystal display device including a hologram color filter that disperses wavelengths in a direction substantially along a recording surface of a hologram or a diffraction grating and disperses the light, a red wavelength region, a green wavelength region, and a blue wavelength region are respectively provided as light sources of the illumination light. A fluorescent tube having at least one bright line peak in the red wavelength region and the main bright line peak wavelength in the blue wavelength region being substantially symmetrical with respect to the main bright line peak wavelength in the green wavelength region. It is a thing.

In this case, when the wavelength difference between the main emission line peak wavelength in the green wavelength region and the main emission line peak wavelength in the red wavelength region is 1, the main emission line peak wavelength in the blue wavelength region and the main emission line peak wavelength in the green wavelength region are The wavelength difference between the peak wavelengths of the main bright lines is preferably between 0.6 and 1.6.

Further, it is desirable to provide a means for converting the diffused light from the fluorescent tube into a substantially parallel light flux having a uniform direction. A wedge-shaped light guide plate, a louver, or the like is used as the means. It is also possible to provide a light beam direction conversion element that converts the direction of the substantially parallel light beam emitted from the means. A minute catadioptric prism assembly or the like is conceivable as the light flux direction conversion element.

Further, the present invention has at least one bright line peak in each of the red wavelength region, the green wavelength region and the blue wavelength region, and the main bright line peak wavelength in the green wavelength region and the main bright line peak in the red wavelength region. When the wavelength difference between the wavelengths is 1, the wavelength difference between the main emission line peak wavelength in the blue wavelength region and the main emission line peak wavelength in the green wavelength region is between 0.6 and 1.6. It includes a fluorescent tube that operates.

In the present invention, as a light source of illumination light,
There is at least one bright line peak in each of the red wavelength region, the green wavelength region, and the blue wavelength region, and the main bright line peak wavelengths of the red wavelength region and the blue wavelength region are substantially symmetrical with respect to the main bright line peak wavelength in the green wavelength region. Since the fluorescent tube located at
It is possible to make all the light of the three colors dispersed by the hologram color filter enter the respective openings of RGB of the black matrix, and the color balance is good and sufficient color reproducibility is obtained, and the use of illumination light The efficiency can be greatly improved.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION A liquid crystal display device using the hologram color filter of the present invention will be described below based on embodiments. The present invention is a liquid crystal display device using the hologram color filters shown in FIGS. 7 to 9, and more particularly, in a direct-viewing type liquid crystal display device, as a light source for the backlight 3, it is substantially symmetric about the G peak line wavelength. By using a three-wavelength fluorescent tube having the peak wavelengths of R and B emission lines, it is possible to allow all three color lights dispersed by the hologram color filter 5 or 10 to enter the respective RGB openings of the black matrix. The color balance is improved so that sufficient color reproducibility can be obtained.

FIG. 6 is a diagram showing an emission spectrum of a commonly used three-wavelength fluorescent tube. The peak wavelengths of the bright lines of the three colors are around 430 nm for blue (B), around 545 nm for green (G), and around 610 nm for red (R).

By the way, for example, as shown in FIG. 7, the focusing positions for the apertures for R, G and B pixels of the black matrix 4 of each wavelength diffracted and dispersed by the hologram color filter 5 are as shown in FIG. . In this example,
One micro hologram 5'and a pair of adjacent R, G,
The size of the color separation pixel of B is 330 μm × 330 μm,
The incident angle θ of the backlight 3 is 40 °, and the focal length of the minute hologram 5 ′ is 2.2 mm.

As is clear from FIG. 5, G of 545n
The bright line near m and the bright line near 610 nm of R are black.
It is incident on the G and R openings of the matrix 4 and G pixels,
Although it is used for displaying R pixels, the bright line of B near 430 nm cannot enter the aperture for B and is blocked by the black matrix 4. Therefore, B of 43
Since the bright line near 0 nm is not used for the display of the B pixel, the color balance of RGB three-color display cannot be obtained.

Therefore, as shown by the broken line in FIG.
When the configuration and arrangement are changed so that the bright line near 430 nm of B is incident on the aperture for B, this time, it becomes 610 n of R.
The bright line near m cannot enter the opening for R and is blocked by the black matrix 4. Therefore, similarly, color balance of RGB three-color display cannot be achieved.

Therefore, in the present invention, as a three-wavelength fluorescent tube, an R that is substantially symmetrical with respect to the G peak line wavelength is centered.
By using a three-wavelength fluorescent tube having the peak wavelengths of the B and B emission lines, it is possible to prevent the above R or B emission lines from being blocked by the black matrix 4,
The three RGB bright lines respectively enter the openings of all RGB of the matrix 4 and are used for the display of the R pixel, the G pixel, and the B pixel, thereby achieving the color balance of the three-color display.

FIG. 4 shows an example of the emission spectrum of a three-wavelength fluorescent tube satisfying such conditions. The peak wavelengths of the bright lines of the three colors are around 480 nm for blue (B) and green (G).
In the vicinity of 545 nm and in the vicinity of 610 nm in the case of red (R) (the sub-wavelength peak in the B region of FIG.
m was changed to be the main peak), in this case,
The wavelength difference between the BG bright line peaks is 65 nm and the wavelength difference between the GR bright line peaks is 65 nm, and the R and B bright line peak wavelengths are symmetrical with respect to the G bright line peak wavelength. When a three-wavelength fluorescent tube having such an emission spectrum is used as a light source for the backlight 3, as shown in FIG. 3A, the three RGB bright lines diffracted and separated by the minute hologram 5 ′ of the hologram color filter 5 are The light enters the apertures for the corresponding colors of the black matrix 4 and is used for displaying the spectral pixels of the respective colors, so that the color balance of the three-color display can be sufficiently obtained.

As described above, in order to achieve color balance of three-color display, the G region (wavelength range 500
Centered on the peak wavelength of the bright line in
When the wavelength difference between the bright line peaks of G is 1, the wavelength difference between the bright line peaks of BG must be between 0.6 and 1.6. It is said that the R and B emission line peak wavelengths are located substantially symmetrically. The wavelength range of the B region is 400 to 500 nm, and the wavelength range of the R region is 600 to 700 nm.

Hereinafter, referring to FIG. 1, a three-wavelength fluorescent tube 3 having an emission spectrum such that the R and B emission line peak wavelengths are located substantially symmetrically with respect to the G emission line peak wavelength as described above.
An example in which a direct-view color liquid crystal display device using the hologram color filter 5 as shown in FIG. In this example, the diffused light from the three-wavelength fluorescent tube 30 is made incident from one end of a wedge-shaped light guide plate 31 made of a transparent material such as acrylic resin, and a substantially parallel light flux whose direction is aligned is emitted from the side surface thereof. A collimated light beam is made incident substantially along one surface of a micro catadioptric prism assembly 32 called a lens film, a collimated light beam is emitted from its opposite surface at a predetermined emission angle, and the collimated light beam is made incident on the hologram color filter 5. The light 3 is used, and the combination of the hologram color filter 5, the black matrix 4 and the liquid crystal display element 6 is the same as in FIGS. 7 and 9, and the operation of the hologram color filter 5 is also the same. As a result, the color balance of the three-color display can be sufficiently obtained, and bright color display can be performed.

In the case of the example of FIG. 1, the light guide plate 31, the minute catadioptric prism assembly 32, and the hologram color filter 5 are used.
Are arranged in parallel to each other, and from the front surface of the light guide plate 31 made of acrylic resin, the diffused light having the above-described emission spectrum from the three-wavelength fluorescent tube 30 is a substantially parallel light flux with an exit angle of 81 °. Is converted into and ejected. The micro catadioptric prism assembly 32 has a partial cross section as shown in FIG.
3 is arranged in parallel, and when the refractive index is 1.57 at an angle as shown in the figure, the exit angle from the light guide plate 31 is 8
A substantially parallel light beam emitted at 1 ° is emitted from a plane on the opposite side of the minute catadioptric prism assembly 32 at an emission angle of 40 ° and is incident on the hologram color filter 5 at an incident angle θ = 40 °.

Similarly, when the hologram color filter 10 as shown in FIG. 8 is used, a direct-view type can be constructed, and in this case also bright color display with sufficient color balance can be performed.

The liquid crystal display device using the hologram color filter of the present invention has been described above based on the embodiments, but the present invention is not limited to these embodiments and various modifications can be made. The hologram color filters 5 and 1
The hologram of 0 is not limited to the one composed of a single layer or a single hologram, but Japanese Patent Application No. 7-290819,
As described in JP-A 7-290820, two or more layers or two or more layers in which the spatial wavelength distributions of wavelength dispersion are substantially the same and the peak wavelengths of diffraction efficiency are different from each other. Alternatively, it may be composed of holograms recorded in multiplex. Further, the means for converting the diffused light from the fluorescent tube into a substantially parallel light flux having a uniform direction is not limited to the above-mentioned wedge-shaped light guide plate, but is disclosed in Japanese Patent Application No.
The waveguide, louver, etc. proposed in Japanese Patent No. 273790 and Japanese Patent Application No. 7-274158 can also be used.

[0037]

As is apparent from the above description, according to the liquid crystal display device using the hologram color filter of the present invention, at least a red wavelength region, a green wavelength region, and a blue wavelength region are at least used as a light source of illumination light. Since a fluorescent tube having one emission line peak and the main emission line peak wavelengths of the red wavelength region and the blue wavelength region being located substantially symmetrically with respect to the main emission line peak wavelength in the green wavelength region is used, RGB of the black matrix are respectively All of the light of three colors separated by the hologram color filter can be made incident on the aperture for use, the color balance is good, sufficient color reproducibility is obtained, and the utilization efficiency of the illumination light is greatly improved. be able to.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of one embodiment of a liquid crystal display device using a hologram color filter according to the present invention.

FIG. 2 is a partial cross-sectional view of a micro catadioptric prism assembly.

FIG. 3 is a diagram showing, in comparison, incident positions of RGB spectroscopic lights in the case of using a fluorescent tube according to the present invention and a conventional fluorescent tube.

FIG. 4 is a diagram showing an example of an emission spectrum of a three-wavelength fluorescent tube satisfying the conditions of the present invention.

FIG. 5 is a diagram showing a focusing position with respect to an aperture of a black matrix of each wavelength, which is diffracted and dispersed by a hologram color filter.

FIG. 6 is a diagram showing an emission spectrum of a commonly used three-wavelength fluorescent tube.

FIG. 7 is a schematic cross-sectional view of a liquid crystal display device using a first type hologram color filter.

FIG. 8 is a schematic cross-sectional view of a liquid crystal display device using a second type hologram color filter.

FIG. 9 is a cross-sectional view of a liquid crystal display element.

[Explanation of symbols]

 3 ... Backlight 4 ... Black matrix 5 ... Hologram array (hologram color filter) 5 '... Micro hologram 6 ... Liquid crystal display element 6' ... Liquid crystal cell 7 ... Hologram 8 ... Light collecting microlens array 8 '... Microlens 10 ... Hologram color filters 12, 13 ... Polarizing plate 21 ... Backlight side glass substrate 22 ... Display surface side glass substrate 23 ... Transparent counter electrode 24 ... Transparent pixel electrode 25 ... Liquid crystal layer 26 ... Substrate 30 ... Three-wavelength fluorescent tube 31 ... Wedge -Shaped light guide plate 32 ... Micro catadioptric prism assembly (lens film) 33 ... Micro catadioptric prism having a triangular cross section

Claims (8)

[Claims] 1. A liquid crystal display element, and an array of element light converging holograms provided on the illumination light incident side thereof, each element light converging hologram having a predetermined distance from a normal line of a hologram recording surface. , A hologram color filter that disperses wavelengths of white light incident at an angle of approximately in the direction along the hologram recording surface, or a hologram or diffraction grating consisting of parallel and uniform interference fringes and its entrance side or exit side. And a composite of a hologram or diffraction grating and an element condensing lens, each of which is composed of an array of element condensing lenses arranged in parallel with each other, and is composed of parallel and uniform interference fringes, and A hologram color filter for wavelength-dispersing white light incident at a predetermined angle with respect to a line in a direction substantially along a recording surface of a hologram or a diffraction grating, and In the liquid crystal display device including, as a light source of the illumination light, having at least one bright line peak in each of the red wavelength region, the green wavelength region, and the blue wavelength region, with the main emission line peak wavelength in the green wavelength region as the center. A liquid crystal display device using a hologram color filter, characterized in that a fluorescent tube in which main emission peak wavelengths in a red wavelength region and a blue wavelength region are positioned substantially symmetrically is used. 2. A main emission line peak wavelength in the blue wavelength region and a main emission line main wavelength in the green wavelength region, where the wavelength difference between the main emission line peak wavelength in the green wavelength region and the main emission line peak wavelength in the red wavelength region is 1. The liquid crystal display device using a hologram color filter according to claim 1, wherein the wavelength difference between the peak wavelengths of the bright lines is between 0.6 and 1.6. 3. A liquid crystal display device using a hologram color filter according to claim 1 or 2, further comprising means for converting diffused light from the fluorescent tube into a substantially parallel light flux having a uniform direction. 4. A liquid crystal display using a hologram color filter according to claim 3, wherein the means for converting the diffused light from the fluorescent tube into a substantially parallel light flux with a uniform direction is a wedge-shaped light guide plate. apparatus. 5. A liquid crystal display device using a hologram color filter according to claim 3, wherein the means for converting the diffused light from the fluorescent tube into a substantially parallel light flux with a uniform direction is a louver. 6. The hologram color filter according to claim 3, further comprising a light beam direction conversion element for converting the direction of the substantially parallel light beam emitted from said means. Liquid crystal display device. 7. A liquid crystal display device using a holographic color filter according to claim 6, wherein the light beam direction changing element is composed of a micro catadioptric prism assembly. 8. A wavelength between at least one bright line peak wavelength in the green wavelength region and at least one bright line peak wavelength in the red wavelength region, and a wavelength between the main bright line peak wavelength in the red wavelength region. When the difference is 1, the fluorescent tube has a wavelength difference between the main emission peak wavelength in the blue wavelength region and the main emission line peak wavelength in the green wavelength region is between 0.6 and 1.6.