KR100464291B1 - Polymer dispersed liquid crystal panel and image projection apparatus using the same and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a polymer dispersed liquid crystal panel, an image projection system using the same, and a method of manufacturing the same. In the polymer dispersed liquid crystal composite panel according to the present invention, the polymer liquid crystal composite is in scattering and transmissive mode, and an etchback type that is simple to manufacture is used as the TFT disposed at the corner of each cell, and light is disposed on the color filter substrate by placing microlenses. Since the leakage current due to the photocurrent generation is reduced and flicker is not generated due to the input signal waveform instability, all the voltages of the driving IC are applied to the pixels, so that there is no cause of deterioration of luminance.

Description

Polymer dispersed liquid crystal panel and image projection device using same and manufacturing method thereof

The present invention relates to a polymer dispersed liquid crystal panel, an image projection system using the same, and a method of manufacturing the same.

A liquid crystal projector is a light, thin, low-power liquid crystal that uses a liquid crystal to expand and project all moving and still images, such as video and TV signals, as well as computer data, up to 300 inches in size. The product is expected to be widely used at home as well as in various conferences and movie theaters. However, the device is still significantly darker than the cathode ray tube (CRT) or overhead projector (OHP) under normal lighting conditions in the room, and the power consumption increases when using a high power light source to increase the brightness. Increasing the temperature of the, the noise of the air-cooled fan increases and the performance degradation due to the temperature rise of the polarizing plate will appear disadvantages. Projection optics using CRTs are bulky, heavy and have high power consumption.

The image projection apparatus using TN (Twisted Nematic) or STN (Super Twisted Nematic) type liquid crystal display panel, which is the mainstream of liquid crystal display devices, uses light polarizers to transmit and block light, resulting in light loss caused by polarizers. The screen is dark due to low light efficiency and high brightness. In addition, when the surface density is required and the pixel density is high, the alignment process around the TFT (Thin Film Transistor) element becomes difficult, and the viewing angle is narrow to about 20 °. In order to solve these drawbacks, PDLC (Polymer Dispersed Liquid Crystal) or PNLC (Polymer Network Liquid Crystal) of light scattering mode has recently emerged. Unlike PDLC, polymers are continuous and liquid crystals form droplets, PNLC is a three-dimensional network structure in which liquid crystals are continuous and polymers are crosslinked. (JP01-198725) and drive voltage is generally lower than PDLC. Since the PDLC does not use a polarizing plate, the light efficiency is high, and thus, the use of the PDLC is very bright, and therefore, the LCD is very bright. In addition, even if the driving voltage and other properties of the PDLC material have a value capable of making a projector, a bright screen can be realized only when the TFT panel and the optical system are supported. Recently developed PDLC materials can be said that the properties such as driving voltage and response speed are enough to make a display.

In PDLC, when the electric field is not applied, the refractive indices of the liquid crystal and the polymer do not coincide, so that incident light is scattered and the cells appear opaque. When an electric field is applied, the liquid crystal is arranged in the electric field direction so that the cell appears transparent. However, since the polarizing plate is not used according to the principle of scattering and transmitting light, the light utilization efficiency is higher and the luminance is excellent and the viewing angle is excellent. Therefore, many efforts have been attempted to use a high-brightness direct-view or projection display using a light transmission / scattering mode without using polarization. However, since the PDLC is in the transmission and scattering mode and the OFF state is the scattering mode, there is a problem in the contrast of the OFF state for use in the direct view. Therefore, it can be said that it is more advantageous to use it as a projection screen of a bright screen.

In order to use PDLC as a projection type liquid crystal display, low voltage driving that can operate within the range of IC driving voltage is required, and in order to realize moving images, it has to have a fast response speed and high maximum transmittance to obtain a high brightness screen. In addition, it must have a physical property having a high contrast ratio which is an essential element. In the early stage of PDLC development, there was a problem that the driving voltage was rather high to be applied to the TFT. However, since the driving voltage was lowered to within 6V due to the progress of the material development, many attempts have been made to apply it to the display using the TFT. The first of these attempts was to disperse liquid crystal in a transparent polymer resin, as disclosed in US Pat. No. 4,435,047. This is evenly dispersed liquid crystal in gelatin, gum arabic or polyvinyl alcohol aqueous solution, and then uniformly coated on the glass plate or polyester film coated with conductive material ITO to 5-20μm thickness, and then evaporated water It is a method of manufacturing by bonding an ITO coated glass plate or a polyester film.

Another more advanced method of preparing a polymer dispersed liquid crystal composite (PDLC) is a phase separation process that utilizes the solubility difference between a polymer and a liquid crystal monomer, as described in US Pat. Nos. 4,688,900 and 4,685,771. This is produced by dissolving the liquid crystal monomer in the monomer or oligomer of the transparent polymer resin and then reducing the solubility of the liquid crystal monomer as the polymerization reaction proceeds by ultraviolet rays or heat, thereby producing the liquid crystal monomer in the form of a droplet. . When the refractive index of the transparent polymer resin is ns, the normal light refractive index of the liquid crystal is no, and the abnormal light refractive index is ne, when the electric field is not applied, the refractive index of ne and ns do not coincide, and incident light is scattered, so that the film appears opaque. When is applied, the liquid crystals are arranged in the electric field direction so that no and ns coincide, and the film appears to be transparent. As described above, the polymer dispersed liquid crystal composite is a polymer dispersed liquid crystal optical shutter made by mixing a prepolymer component and a liquid crystal and curing the polymer component with ultraviolet rays or heat to cause phase separation between the polymer and the liquid crystal. Depending on whether voltage is applied or not, the refractive index of the polymer and the liquid crystal is the same, or the refractive index of the polymer and the liquid crystal does not match, so that light is transmitted or light scattering occurs at the interface between the polymer and the liquid crystal, thereby blocking light incident on the panel. The light is controlled by the light transmission and light scattering methods, thereby realizing an image. However, in the optical projection apparatus using the polymer dispersed liquid crystal composite, since the polarizing plate is not used, the brightness of the screen is improved, but unnecessary scattered light is incident on the screen, which causes the contrast of the screen. That is, since the light emitted from the lamp is divergent and the parallel light efficiency is low, the contrast of the screen is lowered. In order to control the scattered light, there is a method of uniformly distributing the light using two apertures or a prism, but the scattered light is not completely removed.

In order to develop PDLC as a projector through projection, PDLC should be injected into TFT and cured and put into projection optical system. At this time, the strong light of the projection lamp causes leakage current according to the photocurrent according to the structure of TFT, resulting in maximum voltage at PDLC. This may cause a flicker that causes the screen to flicker due to low luminance or distortion of an applied waveform.

On the other hand, the structure of the amorphous silicon (a: Si) TFT for applying a voltage for controlling the phase refractive index and the abnormal refractive index so that the polymer dispersed liquid crystal composite (PDLC) can display an image, the top gate type and There is a bottom gate type. Among them, a bottom gate type having excellent stability and performance is mainly used. There are two types of bottom gate type TFTs, an etch-back TFT and an etch-stopper TFT, depending on the patterning method of the n ⁺ -a: Si film formed on the upper portion of the channel. Etch-stopper TFT amorphous silicon (a: Si) film and an n ⁺ -a: Since the insulating layer between the Si film source - of the channel to the drain electrode as an etching mask, n ⁺ -a: removed by etching the Si . Therefore, the etch-stopper TFT can control the thickness of the amorphous silicon thinner than the etch-back TFT. However, because amorphous silicon increases the current in proportion to the thickness and area of the light, the etch-back TFT is easier to manufacture than the etch-stopper TFT, but when used for OHP and projectors requiring strong light due to the thick amorphous silicon It may cause deterioration of image quality due to increase of OFF current. Therefore, in the case of controlling the refractive index of the polymer liquid crystal composite using an amorphous silicon TFT, it is necessary to minimize the leakage current due to the photocurrent.

The present invention was devised to improve the above problems, focusing the projected light so as not to scatter toward the switching thin film transistor to minimize the leakage current caused by the photocurrent to brighten the image projected on the screen and reduce the occurrence of flicker The present invention provides a polymer dispersed liquid crystal panel, an image projection apparatus using the same, and a method of manufacturing the same.

In order to achieve the above object, the polymer dispersed liquid crystal panel according to the present invention includes two transparent substrates on which stripe-shaped transparent electrodes are formed on the opposite surfaces facing each other at predetermined intervals; Spacers for uniformly spaced apart the two transparent substrates; Scattering and transmissive polymer dispersed liquid crystal composites injected into the empty cells formed by the two substrates and the spacers; A bottom gate type thin film transistor disposed on a substrate on one side of one edge of the cells to apply a driving voltage to the transparent electrode; Microlenses formed on the transparent electrode of the other substrate in each cell region; And a color filter formed on the microlenses.

In the present invention, the bottom gate type thin film transistor is an etch-back type amorphous silicon thin film transistor, and the microlens is formed of a photocurable cinnamic acid ester-based cinnamilcinnamate, and a binder has the same amount of PMMA as cinnamilcinnamate. It is preferred to be used.

In addition, the image projection apparatus using the polymer dispersed liquid crystal panel according to the present invention in order to achieve the above object, the lamp as a light source; A scrambler for evening the intensity of incident light from the lamp; An imaging lens for making divergent light from the scrambler into divergent light of a predetermined angle or less so as to be close to parallel light; A cold mirror that transmits and radiates infrared rays from the diverging light from the imaging lens and reflects the remaining ultraviolet rays and visible light to change an optical path; An ultraviolet filter that blocks the ultraviolet light and transmits the visible light; A first color separation dichroic mirror which transmits a first color light of the three primary colors and reflects the remaining second and third colors of light in the visible light; A second color dichroic mirror for transmitting the second color light among the second and third color light and reflecting the third color light to change an optical path; A first mirror reflecting the first color light to change an optical path; First, second, and third collimation lenses that respectively make the incident first, second, and three color lights into parallel lights; The first, second and third parallel lights incident from the first, second and third collimating lenses are respectively adjusted to transmit light according to a driving voltage applied to the first, second and third collimating lenses to form image lights. Two transparent substrates on which transparent electrodes on a stripe are formed on opposite opposing surfaces spaced apart from each other at intervals, a spacer for uniformly spaced apart the two transparent substrates at the interval, the two substrates, and the spacers A polymer dispersed liquid crystal composite injected into empty cells formed by the same, a bottom gate type thin film transistor disposed on a substrate on one side of one edge of the cells to apply a driving voltage to the transparent electrode, and the other side in each cell region. Microlenses formed on the transparent electrode of the substrate and a color filter formed on the microlenses Of the first polymer dispersed liquid crystal panel 1, 2 and 3, each having; First, second, and third collection lenses that focus the light for the image, respectively; The focused first color light from the first collection lens is transmitted, and the focused third color light from the third collection lens is reflected to equalize the path of the focused first color light and the third color light. A first color synthesizing dichroic mirror to be synthesized; A second mirror reflecting the second color light from the second collection lens to change an optical path; The focused second color light from the second mirror is transmitted, and the focused first and tricolor light from the first color synthesizing dichroic mirror are reflected to reflect the focused first, second and tricolor light. A second color synthesizing dichroic mirror that matches and combines paths; A projection lens for projecting the focused first, second, and three colors of image light from the second color-synthesizing dichroic mirror onto a screen; And an aperture for removing scattered light mixed in the focused first, second and three colors of image light and adjusting luminance.

In the present invention, the polymer dispersed liquid crystal composite is scattered and transmissive, the bottom gate type thin film transistor is an etch-back type amorphous silicon thin film transistor, the microlens is formed of a photocurable cinnamic acid ester-based cinnamilcinnamate The same amount of PMMA as cinnamilcinnamate is used as the binder, and the color filters of the polymer dispersed liquid crystal panels of the first, second and third are preferably red, green, and blue, respectively.

In addition, in order to achieve the above object, a method of manufacturing a polymer dispersed liquid crystal panel according to the present invention includes an etchback type amorphous silicon thin film transistor having a bottom gate type at one corner of each cell region on one substrate of two transparent substrates facing each other. Forming a; Forming a black matrix on a region of the other substrate corresponding to the thin film transistor; Coating a photocurable cinnamic acid ester compound on the other substrate and the black matrix; Irradiating light to the photocurable cinnamic acid ester compound using the black matrix as a mask to form a microlens; And forming a color filter on the microlens.

In the present invention, the forming of the etch back type amorphous silicon thin film transistor may include sequentially forming a gate insulating film, an amorphous silicon film, an n ⁺ -amorphous silicon film, and a metal layer for source and drain electrodes on the one side substrate on which the gate line is formed. Forming a sub-step; Patterning the metal layers for the source and drain electrodes to form source and drain electrodes; And sub-selectively etching the n ⁺ -amorphous silicon film and the amorphous silicon film using the source and drain electrodes as masks to etch a predetermined depth of the amorphous silicon film.

In the present invention, the source and drain electrode metal layer is made of Cr, Ti, Al, the black matrix is formed of chromium, the photocurable cinnamic acid ester compound is cinnamil cinnamate, a binder The same amount of PMMA as the cinnamilcinnamate is used, and the irradiated light is light emitted from a mercury lamp or a xenon lamp, and the color filter is preferably formed by a dyeing method or a printing method.

Hereinafter, an image projection apparatus using a polymer dispersed liquid crystal panel according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic layout view of an image projection optical system using three polymer dispersed liquid crystal panels according to the present invention. As shown, an optical system of an image projection apparatus using three polymer dispersed liquid crystal composite panels includes a scrambler 21, an imaging lens 22, and a cold mirror 23 in front of a lamp 20, Infrared rays are transmitted by the cold mirror 23 and the ultraviolet rays filter 24, the mirrors 25a and 25b, the polymer dispersed liquid crystal complexes 26, 28 and 31 and the dichroic mirror for color separation are provided in the path of the remaining reflected light. (27a, 27b; Dichroic mirror) and color-synthesizing dichroic mirrors 27c, 27d are disposed. Collimation lenses 29a, 29b, and 29c and collection lenses 30a, 30b, and 30c, respectively, are disposed in front and behind the polymer dispersed liquid crystal composite panels 26, 28, and 31. Finally, the light exiting the collection lenses 30a, 30b, and 30c is controlled by the aperture 32 and the image is formed on the screen by the projection lens 33.

As described above, the optical system of the image projection apparatus using three polymer dispersed liquid crystal panels having the functions of color filters of red, green, and blue, respectively, operates as follows.

Light is emitted from the lamp 20 and light is incident on the scrambler 21. Uniform light is made in the scrambler 21 and is incident on the imaging lens 22. The imaging lens 22 produces parallel light that emits incident light within 3 degrees. In the balanced light having an angle of divergence within 3 °, infrared rays in the long wavelength region are diverged through the cold mirror 23, and the remaining visible light is reflected and incident on the ultraviolet filter 24, where the ultraviolet rays are removed. The visible light passing through the ultraviolet filter 24 is transmitted by the dichroic mirror 27a to the light having a red wavelength and proceeds to the mirror 25b, and is reflected by the mirror 25b to collide the lens 29c. Incident. Light of the remaining green and blue wavelengths is reflected by the dichroic mirror 27a and is incident to the dichroic mirror 27b. Blue and green light incident on the dichroic mirror 27b are separated again by the dichroic mirror 27b. The light of the blue wavelength is incident on the collimation lens 29b, and the light of the green wavelength is reflected. And enters the collimation lens 29a. Green, blue, and red wavelengths of light incident on the collimation lenses 29a, 29b, and 29c respectively become fully balanced light and enter the polymer / liquid crystal composite panels 28, 26, and 31, respectively. The polymer / liquid crystal composite panels 26, 28, and 31 transmit or scatter red, green, and blue color light incident by the applied voltage, respectively, and the intensity of each color light is controlled by the voltage applied to each panel. do. The red light passing through the polymer / liquid crystal panel 31 passes through the color synthesizing dichroic mirror 27c, and the green light passing through the polymer / liquid crystal panel 28 passes to the dichroic mirror 27c. Reflected by it, the red light and green light are combined and directed to the dichroic mirror 27d. Green light and red light are combined in the dichroic mirror 27d and directed to the dichroic mirror 27d. The blue light transmitted through the polymer / liquid crystal composite panel 26 is reflected by the mirror 25a to enter the color-composite dichroic mirror 27d. In the dichroic mirror 27d, blue light from the mirror 25a is transmitted, and the red light and green light from the dichroic mirror 27c are reflected to combine three colors of red, green, and blue light. . Therefore, the color is determined by the amount of transmitted light of R, G, and B, and the red, blue, and green light of which the light amount is adjusted is added to the projection lens 33 to be incident. At this time, the light exiting the polymer / liquid crystal composite panels 26, 28, and 31 should be collected in the projection lens 33, so that the light is focused by the respective collection lenses 30b, 30a, and 30c and incident on the projection lens 33. do. The projection lens 33 projects the incident light on the screen. Unnecessarily scattered light due to the light scattering characteristics of the polymer / liquid crystal composite lowers the contrast of the image. Is controlled by That is, opening the aperture 32 increases the scattered light to decrease the contrast, and closing closes the scattered light to increase the contrast. In addition, the aperture 32 functions to adjust not only the scattered light but also the brightness of the screen. When the aperture 32 is opened, the luminance increases, and when the aperture 32 is closed, the luminance decreases.

In the polymer dispersed liquid crystal composite panel used in the optical system of the image projection apparatus as described above, the amount of passing light for forming each pixel of the image is determined by the difference between the refractive index of the polymer resin and the abnormal light refractive index of the liquid crystal as described above. do. This difference in refractive index is determined by the voltage applied to the polymer dispersed liquid crystal composite, and this voltage is provided by the thin film transistor having a structure as shown in Figs. 2A and 2B. In general, polysilicon (poly silicon) has the advantage that the system can be miniaturized because it can be embedded into the drive IC compared to amorphous silicon (amorphous silicon), but it is difficult to realize the large-scale and complicated manufacturing, it has a disadvantage of Figure 2a and As shown in FIG. 2B, an amorphous silicon thin film transistor is mainly used as a thin film transistor (TFT) applied to a polymer dispersed liquid crystal composite and used for switching (for voltage application).

The structure of the amorphous silicon TFT includes a top gate type and a bottom gate type, but a bottom gate type, as shown in Figs. 2A and 2B, which is excellent in stability and performance, is mainly used. 2A is a vertical cross-sectional view of an etch-back (E / B) type thin film transistor, and FIG. 2B is a vertical cross-sectional view of an etch-stop (E / S) type thin film transistor.

Relatively low resistance metals such as Cr, Ta, and Al are used as the gate 4 and 14 electrodes, and silicon nitride films (SiNx; 7, 17, 18) and a-Si semiconductor films are used as gate insulating films thereon. (1, 11). Cr, Ti, Al, etc. are used as the source (2, 12) and drain (3, 13) electrodes, and the source (2, 12), drain (3, 13) electrodes and the a-Si film (1, 11) In between, there is a low resistance n ⁺ -a: Si film doped with phosphorus, which plays an important role in securing ON current by electrons and reducing OFF current by holes. Amorphous silicon is divided into an etch-back type and an etch-stopper type as shown in Figs. 2A and 2B according to the patterning method of the n ⁺ -a: Si films 6 and 16 formed on the channel.

In the etch-back TFT of FIG. 2A, the gate insulating film 7, the a: Si film 1, and the n ⁺ -a: Si film 6 are continuously grown, and then the source 2 and drain 3 electrodes are formed. The n ⁺ -a: Si film 6 is etched and removed by a certain thickness using an etching mask. At this time, since the n ⁺ -a: Si film 6 and the a: Si film 1 below it are the same material, it is difficult to selectively etch. Therefore, a method of adjusting the etching thickness in consideration of the etching rate, etching uniformity and reproducibility of the n ⁺ -a: Si film 6 during plasma etching is used. Accordingly, the thickness of the a: Si film 1 is increased to about 3,4 times that of n ⁺ -a: Si in consideration of the process margin. Since a: Si increases the current in proportion to the thickness and area of the light, thicker a: Si may cause deterioration of the quality when applied to OHP or projectors that require strong light.

In the etch-stopper type of FIG. 2B, the gate insulating film 17, the a: Si film 11, the SiNx film 18 for the etch-stopper (for etching stop) are grown in succession, and then the channel length and width of the TFT are increased. The etch-stopper SiNx film 18 to be patterned is patterned. On top of n ⁺ -a: depositing a Si respectively etched back to a: by the formation of islands, and source 12 and drain 13 electrodes of the Si film 11 as an etching mask for the channel n ⁺ -a: The Si film 16 is removed by etching. At this time, even though the n ⁺ -a: Si film 16 is sufficiently etched under the n ⁺ -a: Si film 16, the a-Si film 11 is formed of SiNx even if the n ⁺ -a: Si film 16 is sufficiently etched. Protected by a membrane 18. Therefore, since the a: Si thickness can be controlled sufficiently lower than that of the etch-back type, the leakage current can be minimized. Therefore, since the etch-stopper TFT has a smaller leakage current than the etch-back TFT, it is advantageous to use as an OHP or a projector, but there is a process difficulty in that the PR process is added once more and more precisely controlled.

In the present invention, a simple etch-back TFT process is used, and as shown in FIG. 3, the microlens 43 is placed on the front glass substrate 5 ′ in the direction of the color filter 41 of the polymer dispersed liquid crystal composite panel. It is arranged to minimize the leakage current of the TFT. A plan view of the unit pixel of the polymer dispersed liquid crystal composite panel is illustrated in FIG. 4 (perspective plan view). The leakage current due to light, that is, the photocurrent to the TFT is generated when strong light is irradiated to the TFT 50 in one pixel as shown in FIG. Therefore, if the strong light is not irradiated near the TFT 50, the photocurrent can be minimized. In order to eliminate such leakage current due to light (hereinafter referred to as “photocurrent”), the color filter 41 placed on the front glass substrate 5 ′ for each unit pixel of the polymer dispersed liquid crystal panel is shown in FIG. 3. A microlens 43 is provided to focus light so that light is not irradiated to the TFT. If this is explained in more detail as follows.

First, a black matrix 40 such as chromium is coated on the front glass substrate 5 ', and the color filters 41 of red (R), green (G), and blue (B) are disposed here. The lens 43 is arranged so that light is focused only near the pixel ITO electrode 51 as shown in FIG. The microlens 43 is manufactured using a photocurable cinnamic acid ester such as cinnamilcinnamate and the like, and a PMMA of about the same amount as cinnamilcinnamate is used as a binder. The resin mixture is dissolved in a solvent such as dioxane and spin-coated on the front glass substrate 5 'on which the black matrix 40 is already formed. When the coated photocurable mixture is irradiated with light such as a mercury lamp or xenon lamp on the back side of the front glass substrate 5 'for about 1 hour using a black matrix 40 as a mask, the irradiated portion swells and emits light. A microconvex lens 43 for focusing is formed. When the color filter is formed on the microlens 43 thus manufactured using a dyeing method or a printing method, a polymer dispersed liquid crystal panel is completed. When the image projection apparatus is manufactured using the polymer dispersed liquid crystal panel manufactured as described above, the light is focused only in the pixel direction by the microconvex lens 43 and no light current is emitted. At the same time, since the amount of light focused on the pixels is increased, an image projection apparatus capable of obtaining a brighter image with higher light efficiency can be manufactured. Such an image projector can be manufactured very simply because only one step of forming a microlens using a photocurable resin is required before forming a color filter in the manufacturing process of a polymer dispersed liquid crystal panel employing a TFT as a switching element. In operation, the generation of photocurrent can also be blocked very effectively.

The color filter substrate manufactured in this manner is bonded to a TFT substrate coated with a spacer uniformly to a predetermined thickness to form a blank cell. Injecting the polymer liquid crystal dispersion solution is uniformly mixed in such a blank cell and cured with ultraviolet rays to prepare a polymer liquid crystal composite.

The polymer dispersed liquid crystal composite thus prepared is an R, G, B panel in which the transmittance is adjusted differently, and is mounted on the optical system of the image projection apparatus as shown in FIG. 1. The light incident from the light source into the white light is split through the dichroic mirrors into the respective colors and then merged again and projected onto the screen. The screen screen of the image projection apparatus using the polymer dispersed liquid crystal composite thus manufactured appears as a very bright screen because of scattering and transmission mode, and there is no flicker because the generation of leakage current due to the photocurrent flow is greatly reduced. The pixel voltage is also maximized, and high brightness images can be realized without a decrease in luminance.

Embodiments of the polymer dispersed liquid crystal composite panel used in the optical system of the image projection apparatus as described above will be described by comparison with a comparative example.

First, in Example, a 10 wt% solution is prepared by adding dioxane, a polar solvent, to a photocurable mixture in which cinnamilcinnamate and PMMA are mixed 1: 1. The homogeneous mixed solution is spin-coated on a black matrix substrate made of a chromium oxide compound at 3500 rpm for 40 seconds, and the solvent is evaporated at 70 ° C. for 2 minutes. In addition, when a 1 kW mercury lamp is irradiated for one hour using a black matrix as a photomask from the rear side of the glass substrate, the pixel area is convexly swelled to form a microconvex lens. An RGB color filter is formed on this microconvex lens to complete the color filter substrate. The substrate is manufactured in an etch-back form and bonded to a TFT substrate on which a spacer has been sprayed in advance, thereby forming an empty cell. A homogeneous mixed solution of 20:80 of acrylic polymer monomer and liquid crystal monomer was vacuum-injected into the empty cell thus prepared, and irradiated with ultraviolet rays to cure. When the three TFT PDLCD panels manufactured as described above are applied to the optical system as shown in Fig. 1, an image of high brightness without flickering can be obtained. In fact, the leakage current of TFT PDLCD panel is very low, 0.7pA, so the switching ratio is more than 106, so there is no problem in driving and the illuminance on the screen is more than 1500lux.

Next, as a comparative example, a polymer dispersed liquid crystal panel was manufactured using a substrate prepared in the same manner as in Example, but without a microconvex lens formed on the color filter substrate. In the image projection apparatus using the polymer dispersed liquid crystal panel, strong projection light is irradiated also in the TFT direction, and leakage current by a-Si photocurrent is 1.5pA, causing a lot of flicker in the image and the maximum voltage of the polymer liquid crystal composite film. Since it was not applied, the luminance also decreased a lot, and the screen contrast was 800 lux or less.

As described above, the image projection apparatus using the polymer dispersed liquid crystal composite panel according to the present invention and the method of manufacturing the polymer dispersed liquid crystal panel according to the present invention do not use a polarizing plate because the polymer liquid crystal composite film is scattering and transmissive mode, so that light utilization efficiency is increased. Therefore, it is possible to manufacture a display capable of realizing a high brightness screen. In addition, the manufacturing yield is improved because the manufacturing is simple because no alignment is performed, and defects generated in the alignment process during TFT fabrication are eliminated. In addition, as the TFT uses a simple etch-back type and designs a microlens on the color filter substrate, the light is collected only at the pixel area and does not proceed in the TFT direction. Since the leakage current is reduced, there is no flicker caused by the input signal waveform instability, and the voltages of the driving ICs are all applied to the pixels, thereby making it possible to manufacture a display having no luminance deterioration factor.

1 is a schematic layout view of an image projection optical system according to the present invention;

2A and 2B are vertical cross-sectional views of an amorphous silicon thin film transistor (TFT) used in the polymer / liquid crystal composite panel of the image projection optical system of FIG.

2A is a vertical sectional view of an etch back (E / B) type thin film transistor,

2B is a vertical sectional view of an etch stopper (E / S) type thin film transistor,

3 is an excerpt vertical cross-sectional view of a unit pixel of a polymer dispersed liquid crystal composite panel used in the imaging optical system of FIG. 1;

4 is a schematic perspective plan view of a unit pixel of a polymer dispersed liquid crystal composite panel used in the image projection optical system of FIG. 1.

<Description of Symbols for Main Parts of Drawings>

1,11: a-Si 1 ': etched a-Si

2,12 source electrode 3,13 drain electrode

4,14 gate 5,15 (back) glass substrate

5 ': front glass substrate 6,16: n ⁺ -a: Si

7,17,18: SiNx

20 lamp 21 scrambler

22: imaging lens 23: cold mirror

24: UV filter 25a, 25b: mirror

26, 28, 31: polymer dispersed liquid crystal composite panel

27a, 27b, 27c, 27d: dichroic mirror

29a, 29b, 29c: Collimation Lens

30a, 30b, 30c: collection lens

32: aperture 33: projection lens

40: black matrix 41: color filter

43: microlens 44: PDLC

50: TFT 51: ITO electrode

52: data line 53: storage capacitor

54: gate line

Claims (21)

Two transparent substrates on which transparent electrodes on a stripe are formed on opposite surfaces that face each other at predetermined intervals, respectively; Spacers for uniformly spaced apart the two transparent substrates; A scattered and transmissive polymer dispersed liquid crystal composite that is injected into empty cells formed by the two substrates and the spacers; A bottom gate type thin film transistor disposed on a substrate on one side of one edge of the cells to apply a driving voltage to the transparent electrode; Microlenses formed on the transparent electrode of the other substrate in each cell region; And A color filter formed on the microlenses; Polymer dispersed liquid crystal panel characterized in that the provided. The method of claim 1, Wherein the bottom gate type thin film transistor is an etch-back type amorphous silicon thin film transistor. The method of claim 1, And the bottom gate type thin film transistor is an etch-stopper amorphous silicon thin film transistor. The method of claim 1, The microlens is a polymer dispersed liquid crystal panel, characterized in that formed of a photocurable cinnamic acid ester compound. The method of claim 4, wherein The said photocurable cinnamic acid ester type compound is cinnamil cinnamate, The polymer dispersed liquid crystal panel characterized by the above-mentioned. The method of claim 5, A polymer dispersed liquid crystal panel characterized by using the same amount of PMMA as the cinnamilcinnamate as the binder of the cinnamilcinnamate. Lamps as light sources; A scrambler for evening the intensity of incident light from the lamp; An imaging lens for making divergent light from the scrambler into divergent light of a predetermined angle or less so as to be close to parallel light; A cold mirror that transmits and radiates infrared rays from the diverging light from the imaging lens and reflects the remaining ultraviolet rays and visible light to change an optical path; An ultraviolet filter that blocks the ultraviolet light and transmits the visible light; A first color separation dichroic mirror which transmits a first color light of the three primary colors and reflects the remaining second and third colors of light in the visible light; A second color dichroic mirror for transmitting the second color light among the second and third color light and reflecting the third color light to change an optical path; A first mirror reflecting the first color light to change an optical path; First, second, and third collimation lenses that respectively make the incident first, second, and three color lights into parallel lights; The first, second, and third parallel lights incident from the first, second, and third collimation lenses are respectively adjusted according to a driving voltage applied to the first, second, and third collimating lenses to form image lights. Two transparent substrates on which transparent electrodes on a stripe are formed on opposite opposing surfaces spaced apart from each other at intervals, a spacer for uniformly spaced apart the two transparent substrates at the interval, the two substrates, and the spacers A polymer dispersed liquid crystal composite injected into empty cells formed by the same, a bottom gate type thin film transistor disposed on a substrate on one side of one edge of the cells to apply a driving voltage to the transparent electrode, and the other side in each cell region. Microlenses formed on the transparent electrode of the substrate and a color filter formed on the microlenses First, second and third polymer dispersed liquid crystal panels, respectively; First, second, and third collection lenses that focus the light for the image, respectively; The focused first color light from the first collection lens is transmitted, and the focused third color light from the third collection lens is reflected to equalize the path of the focused first color light and the third color light. A first color synthesizing dichroic mirror to be synthesized; A second mirror reflecting the second color light from the second collection lens to change an optical path; The focused second color light from the second mirror is transmitted, and the focused first and tricolor light from the first color synthesizing dichroic mirror are reflected to reflect the focused first, second and tricolor light. A second color synthesizing dichroic mirror that matches and combines paths; A projection lens for projecting the focused first, second, and three colors of image light from the second color-synthesizing dichroic mirror onto a screen; And An aperture for removing scattered light mixed in the focused first, second and three colors of image light and adjusting luminance; An image projection apparatus, characterized in that provided. The method of claim 7, wherein The polymer dispersed liquid crystal composite is an image projection device, characterized in that the scattering and transmission. The method of claim 7, wherein And the bottom gate type thin film transistor is an etch-back type amorphous silicon thin film transistor. The method of claim 7, wherein And the bottom gate type thin film transistor is an etch-stopper amorphous silicon thin film transistor. The method of claim 7, wherein The microlens is an image projection apparatus, characterized in that formed of a photocurable cinnamic acid ester compound. The method of claim 11, Said photocurable cinnamic acid ester type compound is cinnamil cinnamate, The image projection apparatus characterized by the above-mentioned. The method of claim 12, The image projection apparatus characterized by using the same amount of PMMA as the cinnamil cinnamate as the binder of cinnamil cinnamate. The method of claim 7, wherein And the color filters of the first, second and third polymer dispersed liquid crystal panels are red, green, and blue, respectively. Forming an etch-back amorphous silicon thin film transistor as a bottom gate type at one corner of each cell region on one of the two transparent substrates facing each other; Forming a black matrix on a region of the other substrate corresponding to the bottom gate type thin film transistor; Coating a photocurable cinnamic acid ester compound on the other substrate and the black matrix; Irradiating light to the photocurable cinnamic acid ester compound using the black matrix as a mask to form a microlens; And Forming a color filter on the microlens; Method for producing a polymer dispersed liquid crystal panel, characterized in that it comprises. The method of claim 15, Forming the etch back amorphous silicon thin film transistor, A step of sequentially forming a gate insulating film, an amorphous silicon film, an n ⁺ -amorphous silicon film, and a metal layer for source and drain electrodes on the one side substrate on which the gate line is formed; Patterning the metal layers for the source and drain electrodes to form source and drain electrodes; A sub-step of selectively etching the n ⁺ -amorphous silicon film and the amorphous silicon film using the source and drain electrodes as a mask to etch a predetermined depth of the amorphous silicon film; Method for producing a polymer dispersed liquid crystal panel, characterized in that it comprises. The method of claim 16, The metal layer for the source and drain electrodes is deposited with Cr, Ti, Al. The method of claim 15, The black matrix is a method of manufacturing a polymer dispersed liquid crystal panel, characterized in that formed of chromium. The method of claim 15, The said photocurable cinnamic acid ester type compound is cinnamil cinnamate, and the manufacturing method of the polymer dispersed liquid crystal panel characterized by using the same amount of PMMA as said cinnamic cinnamate as a binder. The method of claim 15, The irradiation light is a method of manufacturing a polymer dispersed liquid crystal panel, characterized in that the light emitted from a mercury lamp or xenon lamp. The method of claim 15, The color filter is formed by a dyeing method or a printing method.

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