JPH09281477A - Reflection type direct viewing color display device formed by using hologram color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a reflection type direct viewing color display device of a color liquid crystal display device, etc., for which a back light source is not used by using hologram color filters. SOLUTION: This device consists of the hologram color filters 5 which consist of an array of element light condensing holograms 5' and in which these element light condensing holograms 5' spectrally split the white light 13 made incident at a prescribed angle with the normal of the hologram recording surface by wavelength dispersing the white light in the direction approximately along the hologram recording surface, a reflection type hologram 10 which is arranged near the light condensing surfaces thereof and a transmission type spatial optical modulator 16 arranged between the hologram color filters 5 and the reflection type hologram 10. As a result, the reflection type direct viewing color display device, such as bright color liquid crystal display device, which uses environmental light 13, is obtd. even if a back light source is not used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type direct view color display device using a hologram color filter,
In particular, the present invention relates to a reflective direct-view color display device such as a color liquid crystal display device which does not require a backlight light source, using a hologram color filter and a hologram reflection layer.

[0002]

2. Description of the Related Art Conventionally, the present applicant has filed Japanese Patent Application No. 5-1217.
In No. 0, etc., in order to significantly improve the utilization efficiency of a liquid crystal display backlight, a color filter using a hologram and a liquid crystal display device using the same were proposed.

A liquid crystal display device using this hologram color filter will be briefly described below with reference to the sectional view of FIG. In this figure, the liquid crystal cell 6 'is regularly arranged.
Backlight 3 of liquid crystal display element 6 divided into (pixels)
The hologram array 5 forming the color filter is arranged on the incident side with a space. 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 has a repetition period of R, G, and B color separation pixels, that is, a 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 paper. The micro holograms 5 'are arranged in an array at the same pitch as the repetition pitch. The micro holograms 5' are aligned with each set of three liquid crystal cells 6 'adjacent to each other in the direction of the plane of the liquid crystal display element 6, and each hologram 5' Each of the micro holograms 5 ′ corresponds to the light of the green component in the backlight 3 that enters at an angle θ with respect to the normal to the hologram array 5 and corresponds to the micro hologram 5 ′. It is formed in a Fresnel zone plate shape so that light is condensed on the liquid crystal cell G at the center of the three color separation 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.

[0005] With such a configuration, when the white backlight 3 that enters 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 reduced. Accordingly, the diffraction angle of the minute hologram 5 'is different, and the light condensing position for each wavelength is dispersed in a direction parallel to the hologram array 5 surface. 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.

[0007]

As described above, the above-mentioned hologram color filter proposed by the applicant of the present invention is
It can be used only for a color liquid crystal display device using a backlight, and when only ambient light such as ambient light is used as illumination light,
Each wavelength component is not diffracted and condensed at a desired position. Therefore, it cannot be used for a reflection type direct-viewing type liquid crystal display device or the like which does not require a backlight light source using ambient light as illumination light.

The present invention has been made in view of such a situation, and an object thereof is to use a hologram color filter proposed by the present applicant and reflect a color liquid crystal display device or the like without using a backlight light source. To provide a direct-view type color display device.

[0009]

A reflection type direct-view color display device using a hologram color filter of the present invention for achieving the above object comprises an array of element condensing holograms, each element condensing hologram being A hologram color filter that disperses wavelengths of white light incident at a predetermined angle with respect to the normal line of the hologram recording surface in a direction substantially along the hologram recording surface, and a reflection type disposed near the light condensing surface. It is characterized by comprising a hologram and a transmissive spatial light modulator arranged between the hologram color filter and the reflective hologram.

In this case, the reflection type hologram has interference fringes recorded in the same direction to reflect the light of the wavelength of each color in the vicinity of the position where the white light is dispersed by the hologram color filter and the light of each color is incident. Is desirable. As the transmissive spatial light modulator, for example, a liquid crystal display element can be used.

In the present invention, a hologram color filter and a reflection hologram are used in combination with a transmissive spatial light modulator composed of an aggregate of pixels such as a liquid crystal display element, so that a backlight light source is not used.
A reflective direct-view color display device such as a bright color liquid crystal display device can be obtained by utilizing ambient light.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a reflection type direct-view color display device using the hologram color filter of the present invention will be described below. FIG. 1 shows a schematic cross-sectional view of one embodiment of a reflection type direct-view color display device using the hologram color filter as shown in FIG. In the figure, a hologram color is provided on the incident side of the illumination light 13 in the environment of the transmissive spatial light modulator 16 including a liquid crystal display device, a polymer dispersed liquid crystal (PDLC) display device, etc., which are regularly divided into pixels 16 '. The filters 5 are arranged separately. On the rear surface of the transmissive spatial light modulator 16, a reflective hologram 10, which will be described in detail later, and a light absorbing layer 15 are arranged on the rear surface. A black matrix 4 is arranged between each pixel 16 ′ of the transmissive spatial light modulator 16. The distance between the hologram color filter 5 and the reflection hologram 10 is the focal length of the minute hologram 5 '(focal length).
Is selected approximately equal to.

Also in this case, the hologram color filter 5 is adjacent to the repeating period of the R, G, and B color separation pixels of the transmissive spatial light modulator 16, that is, in the direction of the plane of the transmissive spatial light modulator 16 in the drawing. Corresponding to each set of three pixels 16 ′, the minute holograms 5 ′ are arranged in an array at the same pitch as the repeating pitch, and the minute holograms 5 ′ are in the paper surface of the transmissive spatial light modulator 16. One each is arranged corresponding to each group of three pixels 16 'that are adjacent in the direction, and each minute hologram 5'is the illumination light that is incident at an angle θ with respect to the normal line of the hologram color filter 5. The green component light 11G in 13 is formed in a Fresnel zone plate shape so as to be condensed in the vicinity of the pixel G at the center of the three color separation pixels R, G, B corresponding to the minute hologram 5 '. Is shall. The minute hologram 5'is formed of a transmission hologram such as a relief hologram, a phase hologram, or an amplitude hologram, which has little or no wavelength dependency of diffraction efficiency. 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 an arrangement, when the ambient light 13 is incident from the front surface side of the hologram color filter 5 at an incident angle θ, the hologram color filter 5 wavelength-disperses the light, and the light-collecting position for each wavelength is the hologram color filter 5. Dispersed in a direction parallel to the plane. Among them,
The red wavelength component 11R is near the surface of the reflection hologram 10 at the position of the pixel R displaying red, the green component 11G is near the surface of the reflection hologram 10 at the position of the pixel G displaying green, and the blue component. 11B is configured by arranging the hologram color filter 5 so as to diffract and collect light in the vicinity of the surface of the reflection hologram 10 of the pixel B that displays blue.
At, it passes through each pixel 16 'with almost no attenuation and reaches the reflection hologram 10 at the corresponding position.

Here, the reflection hologram 10 is a volume phase hologram (Lippmann hologram), and each of the red diffraction component 11R, the green diffraction component 11G, and the blue diffraction component 11B corresponding to the ambient light 13 having the incident angle θ is condensed. Interference fringes 10R, 1 in the reflection hologram 10 near the position
0G and 10B are formed so as to reflect only red wavelength light, green wavelength light, and blue wavelength light, respectively, and the inclinations of the interference fringes 10R, 10G, and 10B are:
The red diffraction component 11R and the green diffraction component 11 described above, respectively.
The G and blue diffractive components 11B are configured so as to be reflected and diffracted as reflected lights 12R, 12G, and 12B traveling in substantially the same direction.

By the way, the ambient light 13 incident in the angle range of ±± Δ near the incident angle θ is also wavelength-dispersed by the hologram color filter 5, and each color component 11R, 11G,
The colors are separated in the same manner as 11G, but are diffracted at an angle different from the angle shown by the solid line in FIG. In FIG. 1, only the chief ray of the green component is shown by a broken line. For each color, the incident angle θ
In the case of, the diffraction components 11R, 11G, and 11G are distributed near both sides in the dispersion direction. The interference fringes 10 in the reflection hologram 10 are arranged so that such diffracted components are reflected and diffracted in the same direction as the reflected lights 12R, 12G, and 12B, respectively.
R, 10G, and 10B are also continuously distributed at the positions corresponding to the pixels R, G, and B.

Therefore, not only the incident angle θ but also the ambient light 13 incident on the angle range of θ ± Δ is wavelength-dispersed by the hologram color filter 5, and the red wavelength component 11R therein is distributed to the pixel R displaying red. The incident light is intensity-modulated according to the display state of the pixel and is transmitted, and the reflected light 12 is reflected in a certain direction by the interference fringes 10R in the reflection hologram 10.
It is reflected as R, passes through the pixel R from the back side again, and then enters the hologram color filter 5, and this time it passes through the hologram color filter 5 with almost no diffraction and enters the eye of the observer located in that direction. To do. Similarly, the green wavelength component 11G and the blue wavelength component 11B, which are diffracted and dispersed by the hologram color filter 5, enter the pixels G and B displaying green and blue, respectively, and intensities corresponding to the display states of those pixels. The light is modulated and transmitted, and is reflected by the interference fringes 10G and 10B in the reflection hologram 10 as reflected light 12G and 12B in the same fixed direction as described above, and the pixels G and B are transmitted again from the rear surface side,
Further, it enters the hologram color filter 5, and this time it is transmitted with almost no diffraction by the hologram color filter 5 and enters the eyes of the observer located in that direction. Therefore, a color image can be displayed by combining the modulation states of the pixels R, G, and B. The ambient light 13 outside the angle range of θ ± Δ is partially diffracted by the hologram color filter 5 and partially transmitted to reach the reflection hologram 10, but its incident direction and wavelength are interference fringes 10R, 10R.
Since the diffraction conditions of G and 10B are not satisfied, the light is transmitted through the reflection hologram 10 and is absorbed by the light absorption layer 15, and is not reflected toward the observer.

Therefore, as described above, by using the hologram color filter 5 and the reflection hologram 10 in combination with the transmissive spatial light modulator 16 including an assembly of pixels such as a liquid crystal display element, a backlight light source is obtained. Without using, it is possible to obtain a reflective direct-view color display device such as a bright color liquid crystal display device by utilizing ambient light.

The reflection type direct-view color 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.

[0020]

As is apparent from the above description, according to the reflective direct-view color display device using the hologram color filter of the present invention, the hologram color filter and the reflective hologram are assembled into a group of pixels such as a liquid crystal display element. By using it in combination with a transmissive spatial light modulator composed of a body, a reflective direct-view color display device such as a bright color liquid crystal display device can be obtained by utilizing ambient light without using a backlight light source.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of one embodiment of a reflective direct-view color display device using a hologram color filter of the present invention.

FIG. 2 is a schematic cross-sectional view of a liquid crystal display device using a conventional hologram color filter.

[Explanation of symbols]

 4 ... Black matrix 5 ... Hologram color filter 5 '... Micro hologram 10 ... Reflective hologram 10R ... Red diffraction interference fringe 10G ... Green diffraction interference fringe 10B ... Blue diffraction interference fringe 11R ... Red diffraction component 11G ... Green diffraction component 11B ... Blue diffractive component 12R ... Red reflected light 12G ... Green reflected light 12B ... Blue reflected light 13 ... Ambient light (illumination light) 15 ... Light absorption layer 16 ... Transmissive spatial light modulator 16 '... Pixels R, G, B ... Minutes Color pixel

Claims (3)

[Claims] 1. An array of element condensing holograms, wherein each element condensing hologram makes white light incident at a predetermined angle with respect to a normal line of the hologram recording surface substantially along the hologram recording surface. A hologram color filter that disperses wavelengths in a direction to disperse light, a reflection hologram disposed near the condensing surface of the hologram color filter, and a transmissive spatial light modulator disposed between the hologram color filter and the reflection hologram. A reflection type direct-view color display device using a hologram color filter characterized by the above. 2. The reflection-type hologram is recorded with interference fringes that reflect light of wavelengths of respective colors in the same direction in the vicinity of a position where the white light is dispersed by the hologram color filter and light of respective colors is incident. The reflection type direct-view color display device using the hologram color filter according to claim 1, wherein 3. A reflective direct-view color display device using a hologram color filter according to claim 1, wherein the transmissive spatial light modulator comprises a liquid crystal display element.