JPH06281932A - Liquid crystal display device using hologram - Google Patents

Abstract

PURPOSE:To remarkably improve the using efficrency of a back light for liquid CONSTITUTION:In a liquid crystal display device periodically arranging color filter cells R, G, B with color different from each other for adjacent liquid crystal cells, and irradiating then with the back light 3 from a rear side and performing a color display, one sheet or above of holograms 5, 6 with a diffraction wavelength selectivity for a specific wavelength are arranged on the incident side of the back light 3, and specific wavelength components diffracted by the holograms 5, 6 are made incident on the color filter cells R, B of corresponding colors, and the remaining complementary color not diffracted by holograms 5, 6 is made incident on the correspondind color filter cell G, and respective wavelength components of the back light 3 are made incident on respective color cells efficiently to improve the availability remarkably. Further, the hologram selectively diffracting the complementary color may be added.

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, and more particularly to a liquid crystal display device using a hologram to improve the utilization efficiency of a backlight.

[0002]

2. Description of the Related Art Conventionally, in a color liquid crystal display device using a color filter, a backlight is indispensable for displaying. However, if the white light is directly emitted from the back of the color liquid crystal display device, its utilization efficiency is very low. The main reasons are listed below.

The black matrix other than the cells of each color occupies a large area, and the light impinging on it is wasted. Of the white light incident on each pixel, R (red), G (green),
Since the color components that pass through the B (blue) color filter are limited, other complementary color components are wasted.

In order to solve such a problem, as shown in FIG. 5, for example, a microlens array 2 is installed in front of the color filter 1, and a white light backlight 3 is provided in each of the color filter cells R, G, B. Conventionally, a method of increasing the utilization efficiency of the backlight 3 by collecting the light is known. In FIG. 5, reference numeral 4 indicates a black matrix provided between the color filter cells R, G and B.

[0005]

However, even in this method, the white light 3 is emitted to the respective color filter cells R, G, B.
The above-mentioned problem cannot be solved because the light cannot be spectrally irradiated.

The present invention has been made in view of such problems, and an object thereof is to significantly improve the utilization efficiency of a liquid crystal display backlight by using a hologram. Further, in the present invention, the hologram to be used may be formed by forming a liquid crystal display area for each pixel instead of aligning each pixel, and in that case, a complicated and fine forming process is required. Therefore, mass production is easy.

[0007]

In a liquid crystal display device using a hologram of the present invention that achieves the above object, color filter cells of different colors are periodically arranged with respect to adjacent liquid crystal cells, and a backlight is provided from behind. In a liquid crystal display device that performs color display by irradiating with, a single hologram or a plurality of holograms having a diffraction wavelength selectivity with respect to a specific wavelength is arranged on the incident side of the backlight, and the specific hologram diffracted by the hologram is placed. It is characterized in that the wavelength component is made incident on the color filter cell of the corresponding color.

In this case, the remaining complementary color components that are not diffracted by the above-mentioned single or multiple holograms may be made incident on the color filter cell of the corresponding color.

Further, the hologram may have a condensing property, or may be composed of uniform interference fringes having diffractive wavelength selectivity. In the latter case, it is desirable to dispose the light condensing element on the backlight entrance side or exit side of the hologram at a period corresponding to the above period.

[0010]

According to the present invention, a single hologram or a plurality of holograms having diffraction wavelength selectivity with respect to a specific wavelength is arranged on the incident side of the backlight, and the specific wavelength component diffracted by the hologram is dealt with. Since the color filters are made to enter the color filter cells, the respective wavelength components of the color filter backlight can be made to enter the respective color cells without waste, so that the utilization efficiency thereof can be significantly improved.

[0011]

Embodiments of the liquid crystal display device using the hologram of the present invention will be described below with reference to the drawings. Figure 1
FIG. 3 is a diagram showing a cross section of a main part of the liquid crystal display device according to the first embodiment of the present invention, which is aligned and integrally bonded on a glass substrate 7 on the backlight incident side of the color filter 1 of the liquid crystal display device. Two transmissive holograms 5 and 6 are arranged. The transmissive holograms 5 and 6 are arrayed at the same pitch as the pixel pitch of the color filter 1 corresponding to each set of three color filter cells R, G, and B that form one pixel of the liquid crystal display device. Each of the unit holograms of the transmission type hologram 5 selectively diffracts the blue wavelength component in the white backlight 3 which is incident almost perpendicularly to the color filter 1 and selectively diffracts the blue color filter cell B. It is formed in the shape of a Fresnel zone plate having wavelength selectivity so as to focus light on the light source. Each unit hologram of the transmission hologram 6 selectively diffracts the red wavelength component in the backlight 3. It is formed in a Fresnel zone plate shape having wavelength selectivity so that the light is focused on the red color filter cell R. Here, the transmission hologram having wavelength selectivity is a type in which only a specific wavelength is diffracted and other wavelengths are transmitted without being diffracted, like a Lippmann hologram. Therefore, most of the blue wavelength component in the white backlight 3 which is vertically incident on the color filter 1 from behind the liquid crystal display device is diffracted and condensed by the blue hologram 5 and is incident on the position of the color filter cell B. However, most of the red wavelength component is diffracted and condensed by the red hologram 6 and enters the position of the color filter cell R. The green component which is not diffracted and condensed by the holograms 5 and 6 passes through the holograms 5 and 6 and the glass substrate 7 and goes straight to the color filter cells R and G.
One-third is incident on each of B, but the incident on the color filter cells R and B is blocked by the filter at that position, and is effectively incident on only the color filter cell G. The respective wavelength components pass through the respective color filter cells R, G, B with almost no attenuation, and color display is performed according to the state of the liquid crystal cell at the corresponding position. A liquid crystal display element (not shown) is arranged between the color filter 1 and the holograms 5 and 6 so that the filter cells R, G and B and the liquid crystal cell are aligned.

As described above, in the embodiment of FIG. 1, the color filters in which only the two specific wavelength components are arranged on the exit side of the holograms 5 and 6 by utilizing the wavelength selectivity of diffraction by the holograms 5 and 6. Each wavelength component of the conventional color filter backlight is made by diffracting and entering the corresponding color cells R and B of No. 1 and transmitting the remaining complementary color components to enter the corresponding color cell G. Since the light can be incident on each color cell without waste, the utilization efficiency thereof can be greatly improved. Instead of this, as shown in FIG. 2, a Fresnel zone plate shape having wavelength selectivity as well. The hologram 10 for green color is further added, and the corresponding wavelength components are diffracted and condensed into the corresponding color filter cells by the three holograms 5, 6, and 10. In this case, although the number of holograms increases, each wavelength component of the backlight 3 can be incident on each color cell R, G, B without waste, so that the utilization efficiency thereof is further improved. .

By the way, in the embodiment shown in FIGS. 1 and 2, the color filter cell R constituting one pixel,
The Fresnel zone plate-shaped micro-holograms 5, 6 and 10 are arranged so as to correspond to each group of G and B, but a uniform hologram acting as a diffraction grating having wavelength selectivity. It is possible to significantly improve the utilization efficiency of the liquid crystal display backlight by combining the and the microlens array and similarly utilizing the wavelength selectivity of diffraction. The embodiment will be described with reference to FIG. In FIG. 3, on the front surface of the color filter 1 of the color liquid crystal display device, there is arranged a microlens array 9 in which microlenses 8 having a diameter corresponding to the pixel pitch of the color filter 1 are provided on a glass substrate 7. On the color filter 1 side of the microlens array 9, there are integrally provided a blue hologram 5'and a red hologram 6 ', which are uniform interference fringes having wavelength selectivity. With this configuration, most of the blue wavelength component in the white backlight 3 collected by the microlens 8 is the blue hologram 5 '.
And is condensed at the position of the color filter cell B, and most of the red wavelength component is diffracted by the red hologram 6'and condensed at the position of the color filter cell R.
The green component which is not diffracted by the holograms 5 and 6 goes straight through the holograms 5'and 6'and is condensed at the position of the color filter cell G. Therefore, the red wavelength component of the white incident light 3 is condensed at the position of the color filter cell R, the green component is condensed at the position of the color filter cell G, and the blue component is condensed at the position of the color filter cell B. The components are the color filter cells R, G,
At B, the light passes through with almost no attenuation, and color display is performed according to the state of the liquid crystal cell at the corresponding position. In this embodiment, since the holograms 5'and 6'can be wavelength-selective holograms composed of uniform interference fringes having no light-collecting property, the holograms 5'and 6'are referred to as the color filter 1. Features are that it is not necessary to align, and the pitch of the microlens array 9 is three times that of the conventional case of FIG. 5, making it easy to make and align.
Further, as compared with the embodiment of FIG. 1, since all the complementary color components not diffracted by the holograms 5'and 6'can be made incident on the green color filter cell G, the backlight 3 can be used more efficiently for display. There is. Also in this case, as shown in FIG. 4, as in FIG. 2, a wavelength-selective green hologram 10 'having uniform interference fringes having no light-collecting property is further added, and three holograms 5', 6 ',
It is also possible to diffract the corresponding color components in the white backlight 3 collected by the microlenses 8 by the respective 10 'and make them incident on the corresponding color filter cells.

One specific example of FIG. 3 is shown. Omnipond 352 (film thickness: 10 μm) manufactured by DuPont was used as a photosensitive material, and a light source having a wavelength of 514.5 nm of an argon ion laser (output 5 W) manufactured by Spectra Physics was used.
A blue hologram 5'and a red hologram 6'are created by parallel two-beam interference. This hologram 5 ',
When the diffraction efficiency of 6'was measured for red and blue, it was possible to obtain 99.8% for blue and 85.5% for red. These holograms 5'and 6'are aligned and bonded on one glass substrate 7, and on the back surface thereof, R,
Diameter 30 corresponding to G, B1 set of color filter cells
The 0 μm microlenses 8 were installed in an array. Subsequently, the glass substrate 7 and the color filter 1 are adhered while aligning the positions of the microlens 8 and the color filter 1, and a white parallel light source configured by combining this with a metal halide lamp and a parabolic mirror. Back light 3 of each color filter cell R, G,
When the transmitted light intensity from B was measured, it was 40 to 40 in comparison with the conventional microlens array-only system as shown in FIG.
An efficiency improvement of 50% was observed, confirming the effectiveness of the present invention.

By the way, the above holograms 5, 6,
A known volume type hologram recording material such as a photopolymer can be used as the recording material 5 ′, 6 ′, 10, 10 ′, and the hologram is recorded by two-beam interference. Not only the computer generated hologram but also a computer generated hologram (CG) created by calculating a desired hologram interference fringe with a computer and drawing with an electron beam or the like.
H: Computer Generated Holo
It is also possible to use a hologram that is reproduced by causing the reproduction illumination light and the diffraction light generated when the reproduction illumination light is incident on the gram) to interfere with each other in the closely contacted photosensitive material. Further, instead of the plurality of holograms 5, 6, 5 ', 6', 10, 10 ', one hologram of multiple recording volume type may be used.

In the above, the holograms 5, 6,
The light collecting form of 10 may be a point-like light collecting form on the corresponding color filter cell or a line-like light collecting form. Further, the microphone lens 8 may be a rotationally symmetric lens that collects light in a dot shape on the color filter cell, a cylindrical lens that collects light in a linear shape, a toric lens, or the like.

The liquid crystal display device using the hologram of the present invention has been described above based on several embodiments.
The present invention is not limited to these embodiments and various modifications can be made.

[0018]

As is apparent from the above description, according to the liquid crystal display device using the hologram of the present invention, a single or a plurality of holograms having diffraction wavelength selectivity with respect to a specific wavelength are incident on the backlight. Since the specific wavelength component diffracted by the hologram is made incident on the color filter cell of the corresponding color by arranging it on the side, each wavelength component of the color filter backlight can be made incident on each color cell without waste. Therefore, the utilization efficiency can be greatly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section of a main part of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a view showing a cross section of a main part of a modification of the first embodiment.

FIG. 3 is a diagram showing a cross section of a main part of a liquid crystal display device according to a second embodiment.

FIG. 4 is a diagram showing a cross section of a main part of a modification of the second embodiment.

FIG. 5 is a diagram for explaining a conventional illumination method for a liquid crystal display device.

[Explanation of symbols]

 1 ... Color filter 3 ... Backlight 5 ... Transmissive hologram for blue 6 ... Transmissive hologram for red 7 ... Glass substrate 8 ... Microlens 9 ... Microlens array 10 ... Transmissive hologram for green 5 '... Transmissive hologram for blue 6 '... Transmission hologram for red 10' ... Transmission hologram for green

Claims (4)

[Claims] 1. A liquid crystal display device in which color filter cells of different colors are periodically arranged with respect to adjacent liquid crystal cells and a backlight is irradiated from behind to perform color display, and a diffractive wavelength is obtained with respect to a specific wavelength. It is characterized in that a single or multiple holograms having selectivity are arranged on the incident side of the backlight so that a specific wavelength component diffracted by the hologram is made incident on a color filter cell of a corresponding color. Liquid crystal display device using hologram. 2. The liquid crystal display device using a hologram according to claim 1, wherein the remaining complementary color components that are not diffracted by the hologram are made incident on the color filter cell of the corresponding color. 3. A liquid crystal display device using a hologram according to claim 1, wherein the hologram has a light converging property. 4. The hologram is composed of uniform interference fringes having diffraction wavelength selectivity, and a condensing element is arranged on a backlight incident side or an exit side of the hologram at a period corresponding to the period. A liquid crystal display device using the hologram according to claim 1.