KR19990075996A - Optical amplification panel and projection type liquid crystal display device having same - Google Patents

Abstract

The present invention relates to an optical amplifier panel and a projection type liquid crystal display device having the same. Transparent amplification is formed on the surface facing each other, the optical amplification comprising two transparent substrates bonded to maintain a predetermined gap between the transparent electrodes, and a photorefractive material interposed between the two transparent substrates Using a panel, it is possible to amplify the intensity of image light with optical information. Therefore, according to the present invention, a display device having high brightness can be realized.

Description

Optical amplification panel and projection type liquid crystal display device having same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical amplification panel and a projection type liquid crystal display device having the same, and more particularly, to an optical amplification panel for amplifying the intensity of an image light passing therethrough and a projection type liquid crystal display device having excellent brightness.

Conventional liquid crystal display projectors have a low luminance despite the use of a strong light source. 1 is a view showing a general projection type liquid crystal display device, in which reference numeral 1 denotes a light source, reference numeral 2 denotes a concave mirror, reference numeral 3 denotes a condenser lens, and reference numeral 4 denotes a dichroic mirror. , Reference numerals 5A, 5B, 5C, and 5D are reflecting mirrors, and reference numerals 6A, 6B, and 6C are liquid crystals corresponding to any one of red, blue, and green, respectively. In the panel, reference numeral 7 denotes a synthetic dichroic prism, reference numeral 8 denotes a projection lens, reference numeral 9 denotes means for blocking light outside the straight direction, and reference numeral 10 denotes a projection screen. Elements indicated by reference numerals (1) to (5D) constitute a color light source, and elements indicated by reference numerals (7) to (9) constitute a light projection system.

Referring to Figure 1, the operation principle of the projection type liquid crystal display device will be described. The white light from the light source 1 is divided into three primary colors of red, green and blue by the dichroic mirror 3, and then the panels 6A, 6B and 6C corresponding to the respective colors. Pass through. The light of the three primary colors passing through the panels 6A-6C is synthesized again by the dichroic prism 7 and projected on the screen 10 beyond the projection lens 8.

In the projection type liquid crystal display device operating on the principle as described above, it is common for the liquid crystal panel to adopt a twisted nematic (TN) type liquid crystal. In this case, two polarizing plates are required on both sides of the panel, and this polarizing plate has a problem of lowering the light transmittance and lowering the brightness of the screen.

In order to solve these drawbacks, a liquid crystal display device that does not require a polarizing plate and an alignment has been proposed. U.S. Patent No. 5,103,327 proposes a Polymer Dispersed Liquid Crystal Display (PDLCD) in a light scattering mode in which a polymer is dispersed in a liquid crystal. However, such a display device has a problem that the brightness enhancement effect can be obtained, but the contrast is lowered, making it difficult to be practical.

In addition, a method of improving luminance using a microarrangement has been proposed, but has not been put into practical use in large display devices of 50 inches or more. In addition, although a study of a projector using a laser has been recently conducted, it has not been used in a large projection of 70 inches or more due to a luminance problem.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide an optical amplification panel capable of solving the above problems and amplifying the intensity of image light.

Another object of the present invention is to provide a projection type liquid crystal display device with improved brightness.

1 is a view showing a general projection type liquid crystal display device.

2 is a schematic diagram illustrating a principle of amplifying image light according to the present invention.

In order to achieve the above object, in the present invention, transparent electrodes are formed on surfaces facing each other, and are interposed between two transparent substrates and the two transparent substrates bonded to maintain a predetermined gap between the transparent electrodes. And a photorefractive material having a function of amplifying image light passing therethrough.

In order to achieve the above another object, the present invention includes a liquid crystal panel interposed between a light source and a transparent substrate, a liquid crystal panel for transmitting or blocking the light source, and a light projection system for projecting a light source passing through the liquid crystal panel on a screen. In the projection type liquid crystal display device, an optical amplification panel is provided between the liquid crystal panel and the optical projection system, the optical amplification panel, a transparent electrode is formed on the surface facing each other, the predetermined between the transparent electrode A projection type liquid crystal display device comprising two transparent substrates bonded to each other so as to maintain a spacing therebetween, and a photorefractive material interposed between the two transparent substrates and having an effect of amplifying the image light passing through the two transparent substrates. Is provided.

When projecting polarized image light with some optical information onto a panel exhibiting the photorefractive effect and simultaneously projecting pump light having the same wavelength as the polarized light, the two lights interfere with each other and exhibit a photorefractive effect. . The optical refraction effect can be used to amplify the intensity of the image light, and the present invention is characterized by amplifying the luminance of display elements such as liquid crystal display elements using this principle.

In the present invention, a light used for amplifying red, green, and blue light is used as a He-Ne laser for red, and a second harmonic generator for green and blue. By amplifying each of them, a bright projection screen with natural colors can be obtained.

FIG. 2 is a schematic drawing for explaining the principle of amplifying image light according to the present invention, wherein reference numeral 11 is an optical amplification panel, and reference numeral 12 is an image light having optical information. , Reference numeral 13 is a pump light having the same wavelength as the image light, and reference numeral 14 is light that is amplified and projected while the image light 12 passes through the optical amplification panel. 1 and 2, the image light 12 having optical information through the liquid crystal panel 6A, 6B or 6C passes through the optical amplification panel 11 and then enters the light projection system. At this time, the pump light 13 having the same wavelength as the image light 12 is incident on the optical amplification panel 11, and the image light 12 is amplified in the optical amplification panel 11 by the pump light 13. Will be. Therefore, according to the present invention, the projection type liquid crystal display device having the optical amplification panel has an advantage of excellent brightness.

In the present invention, an optical amplification panel using the photorefractive effect includes a photorefractive material interposed between two transparent substrates and a transparent electrode formed on opposite surfaces of the transparent substrate. Here, the photorefractive material has the function of amplifying the image light passing through it.

In order for an organic material to exhibit a photorefractive effect, a mixed material consisting of a photoconductive material (odd transporter) and a nonlinear optical material (electrooptical chromophore) is required. In other words, when the diffraction pattern of the hologram is formed on the photorefractive material by using the two interfering light, the charge generated in the bright portion moves to the dark side and stays at a certain point, thereby forming a non-uniform internal electric field. The electric field stimulates the nonlinear optical material to cause a spatial change in the refractive index, and as a result, the light and dark pattern due to the optical interference is recorded as the refractive index change pattern.

In this way, the recording principle by optical refraction is the same as the recording principle of the hologram. Recording the wavefront and phase of light as a spatial modulation of the material's refractive index is identical to the photorefractive effect in that it is the fundamental principle of holograms. The difference between optical refraction recording and hologram is that the hologram material causes chemical changes due to light or heat, making it impossible to reuse even with a single optical recording. This is possible.

When the image light and the pump light are incident on the panel containing the material having the photorefraction effect as described above, the carrier is excited by the light at the bright part by the interference pattern, and the charge is spatially distributed by the diffusion of the carrier. . The spatial electric field spatially modulates the refractive index of the secondary nonlinear optical material (chromophore) by the primary electro-optic effect. Here, the change distribution of the refractive index forms a phase grid similar to the interference pattern. Refractive index modulation is represented by a phase shift of ± ½π with respect to light. By the light refraction principle, the energy of the pump light is transferred to the image light, resulting in the light intensity being amplified, thereby amplifying the brightness of the projector.

In the present invention, a conventional photoconductive material and a secondary nonlinear optical material can be used that can exhibit a photorefractive effect. As the photoconductive material, poly (vinylcarvazole), polyvinylcarbazole derivatives, siloxane polymer compounds, phthalocyanine derivatives, hydrazone derivatives and the like are preferable. Meanwhile, 2,4,7-trinitrofluorenone (TNF) is mixed with the photoconductive polymer to form a complex, thereby increasing the light absorption or adjusting the absorption wavelength. In addition, in order to increase the photosensitivity of the photoconductive material, it is preferable to add a single molecule charge generator. Types of charge generators include fullerenes, TCNQ, naphthalene derivatives, and quinone derivatives.

Nonlinear optical materials are important materials for determining the optical refractive effect, and in particular, materials for determining the optical durability of the optical refractive material. As non-optical optical material, which is a component of optical refraction material, the dipole moment and polarization anisotropy should be large in addition to durability, and the light absorption rate should be low. In addition, the solubility in the photoconductive material should be large. Examples of such materials include 2,5-dimethyl-4- (p-nitrophenylazo) anisole [2,5-dimethyl-4- (p-nitrophenylazo) anisole], dimethylbenzaldehydediphenylhydrazone, 4-dimethylamino Most of the organic compound which an electron donor and an electron acceptor exist in both -β-nitrostyrene and a benzene ring between them is mentioned.

In order to obtain the macroelectro-optic properties of the photorefractive material, the nonlinear optical material must be oriented through a polling process by an external electric field. The role of the external electric field is to assist in the generation of charge by reducing the possibility of charge recombination in addition to polling.

Hereinafter, the effects of the present invention will be described in detail through Examples and Comparative Examples, but the present invention is not necessarily limited thereto.

<Example 1>

85 g of a mixture of polyvinylcarbazole and 2,4,7-trinitrofluorenone (weight ratio 55:30) as a photoconductive material, 2,5-dimethyl-4- as a secondary nonlinear material A photorefractive material consisting of 14 g of (p-nitrophenylazo) anisole and 1 g of n-ethylcarbazole as an additive was prepared. Two transparent substrates each having an indium tin oxide (ITO) electrode formed on each surface were bonded to each other to prepare a panel having empty cells having a thickness of 100 μm. The photorefractive material obtained in the above step was injected into an empty cell, followed by polling by applying an electric field at 180 ° C., followed by cooling to prepare a photorefractive cell.

The 30 nm polarized He-Ne laser was irradiated with a pump laser at a 45 degree angle in the normal direction while simultaneously injecting a 30 nm polarized He-Ne laser in the normal direction of the cell. At this time, it was confirmed that the intensity of light emitted from the photorefractive cell was amplified by 1.7 times the light intensity of the 30 kHz polarized He-Ne laser incident in the normal direction of the cell.

<Example 2>

Except for the use of green and blue lasers whose wavelengths differ from those in Example 1, the effects of the photorefractive cells were tested in the same manner as in Example 1, with the light intensity of 1.7 times and 1.8 times amplification was confirmed.

As can be seen from the above, the use of the optical amplification panel makes it possible to amplify the intensity of the image light. Therefore, the projection type liquid crystal display device according to the present invention has an advantage that the luminance is high by providing an optical amplifier panel.

Claims (8)

Two transparent substrates are formed on the surface facing each other, the two transparent substrates are bonded to maintain a predetermined gap between the transparent electrodes; And And an optical refraction material interposed between the two transparent substrates and having a function of amplifying the image light passing therethrough. The method of claim 1, wherein the photorefractive material, An optical amplification panel comprising a photoconductive material and a secondary nonlinear optical material. The method of claim 2, wherein the photoconductive material, An optically amplified panel, characterized in that at least one selected from the group consisting of polyvinylcarbazole derivatives, siloxane polymer compounds, phthalocyanine derivatives, and hydrazone derivatives. The method of claim 2, wherein the secondary nonlinear optical material, 2,5-dimethyl-4- (p-nitrophenylazo) anisole, dimethylbenzaldehydediphenylhydrazone, 4-dimethylamino-β-nitrostyrene, and a benzene ring in between the electron donor and electron acceptor An optical amplification panel, characterized in that at least one selected from the group consisting of organic compounds present. Light source; A liquid crystal panel interposed between the transparent substrates and transmitting or blocking the light source; And A projection type liquid crystal display device comprising a light projection system for projecting a light source passing through the liquid crystal panel on a screen, An optical amplifier panel is provided between the liquid crystal panel and the optical projection system. The optical amplifier panel, Two transparent substrates are formed on the surface facing each other, the two transparent substrates are bonded to maintain a predetermined gap between the transparent electrodes; And And a photorefractive material interposed between the two transparent substrates and having a function of amplifying the image light passing through the two transparent substrates. 6. The liquid crystal display of claim 5, wherein the photorefractive material comprises a photoconductive material and a secondary nonlinear optical material. The liquid crystal display of claim 6, wherein the photoconductive material is at least one selected from the group consisting of polyvinylcarbazole derivatives, siloxane polymer compounds, phthalocyanine derivatives, and hydrazone derivatives. The method of claim 6, wherein the secondary nonlinear optical material, 2,5-dimethyl-4- (p-nitrophenylazo) anisole, dimethylbenzaldehydediphenylhydrazone, 4-dimethylamino-β-nitrostyrene, and a benzene ring in between the electron donor and electron acceptor A projection type liquid crystal display device, characterized in that at least one selected from the group consisting of organic compounds present.