JPH0990336A - Transmission type color liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance brightness and to reduce the diameter of projecting lenses by combining flat plate type microlens arrays with a color liquid crystal display element of a transmission type. SOLUTION: The transmission type liquid crystal display element 1 is constituted by packing liquid crystals 5 into the spacing 4 between translucent panels 2 and 3. The translucent panel 2 existing on the incident side of irradiation light is constituted by laminating the first and second flat plate type microlens arrays 6, 7. The thicknesses of glass substrates 8, 11 are adjusted by polishing in order to match the focal lengths, etc., of these flat plate microlens arrays 6, 7 with set values. The formation of the lens parts 10, 13 of the flat plate type microlens arrays 6, 7 is executed by forming recessed parts 9, 12 by etching on the fire finish surfaces of the glass substrates 8, 11 and packing high- refractive index resins into these recessed parts 9, 12, thereby forming the lens parts 10, 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive color liquid crystal display device incorporated in a liquid crystal projector or a projector television (PTV) for enlarging and displaying a television screen or a computer screen.

[0002]

2. Description of the Related Art A projector using a liquid crystal display element capable of brightening a screen according to the brightness of an irradiation light source has come to be used instead of a cathode ray tube type projector. As such a liquid crystal display element, a transmissive liquid crystal display element and a reflective liquid crystal display element, in which irradiation light is incident on a liquid crystal layer on which an image is formed, and irradiation light transmitted through the liquid crystal layer is projected onto a screen through an optical system. There is.

Further, as a projector for color display, there is a single plate type using a mosaic-type three primary color filter in addition to a system using a liquid crystal display element for each of the three primary colors. Since only 1/3 of the light is used, as a technique improving this, Japanese Patent Laid-Open No. 4-60
There is one disclosed in Japanese Patent No. 538.

The projector disclosed in Japanese Patent Laid-Open No. 4-60538 is shown in FIG. 7 and FIG.
As shown in, the dichroic mirror 101 applies the irradiation light emitted from the white light source 100 to red (R), blue (B),
The green (G) three primary colors are separated, the separated three primary color lights are incident on the liquid crystal display element 102 at different angles, and the light emitted from the liquid crystal display element 102 is passed through the field lens 103 and the projection lens 104 to a screen 105. It is configured to project on.

The liquid crystal display element 102 includes a glass substrate 106,
The scanning electrode 106a and the signal electrode 107a are provided on the facing surface of 107.
Liquid crystal 109 is filled in the gap between the glass substrates 106 and 107 formed by the spacer 108, and the flat plate type microlens array 110 is bonded to the glass substrate 106 on the side where the irradiation light is incident. The irradiation light is focused on the signal electrode 107a (pixel electrode).

As described above, by using the flat plate type microlens array 110, most of the irradiation light can be transmitted, so that the image projected on the screen can be brightened. However, the liquid crystal display element 10
Since the divergence angle of the irradiation light that emits 2 becomes large, as shown in FIG.
As shown in (1), the diameter of the projection lens 104 must be increased, and the entire optical system becomes large.

There is a proposal that the diameter of the projection lens can be suppressed even if a flat plate type microlens array is used.
It is disclosed in Japanese Patent No. 41283 or Japanese Patent Laid-Open No. 181487/1995. As shown in FIG. 10, the contents of Japanese Patent Application Laid-Open No. 5-341283 use a microlens array in which lens portions 111 and 112 are formed on both surfaces of a single glass substrate, and irradiation light is emitted from the first lens portion 111. Are concentrated on the pixel opening, and the principal ray of the emitted light is made parallel to the optical axis by the second lens portion 112. Further, the content of Japanese Patent Laid-Open No. 181487/1995 is to bond a microlens array to both sides of one glass substrate.

[0008]

When the double-sided lens shown in FIG. 10 is applied to the optical system shown in FIGS. 7 and 8, the thickness of the substrate 106 is adjusted so that the chief rays of R and B inclined at a specific angle. , It is necessary to set the values so as to enter the pixel electrodes 107a corresponding to R and B of the liquid crystal panel. In many cases, the pixel pitch is given by the liquid crystal panel used, and the tilt angles of the R, G, and B rays are given by the aperture of the projection lens and the layout of the illumination optical system, and then the values of these two values are given. The thickness of the substrate 106 is determined corresponding to. That is, the substrate 106 can have various thicknesses depending on the liquid crystal panel used and the illumination system.

On the other hand, as a method of manufacturing the double-sided lens shown in FIG. 10, a method shown in FIG. 11 can be considered. Glass substrate 110 (for example, Corning # 7059, # 173)
7, NH Techno Glass Co. NA45, NA35, etc.) is covered with a mask 113 and isotropically etched as shown in the figure to form a substantially hemispherical recess 114, and the recess 114 has a high refractive index. The resin is filled to form the microlens array 111, and then the glass substrate 110 is polished to have a desired thickness for the reason described above, and the recessed portion is formed on the polished surface by etching in the same manner as described above. The concave portion is filled with a high refractive index resin to form the microlens array 112.

At this time, if the surface roughness of the polished surface is insufficient and fine scratches remain on the surface, etching proceeds along these scratches, and as shown in FIG.
Will be distorted and the light-collecting characteristics will deteriorate. While various thicknesses are required as the glass substrate as described above, the substrate thickness supplied as the glass substrate is actually some specific thickness such as 1.1 mm and 0.7 mm. In order to obtain a desired thickness, it is often necessary to polish a considerable amount, and it is necessary to adjust the thickness by rough polishing using coarse abrasive grains and a hard pad such as so-called lapping. After such rough polishing, it is extremely difficult to perform finish polishing (polishing) to a level at which the shape is not distorted by etching, and there is a problem that the cost is significantly increased. In the above example, the etching lens is formed on one surface, and then the opposite surface is polished. However, the same problem naturally occurs when both surfaces are polished to a desired thickness. Therefore, FIG.
A double-sided lens configuration such as that shown in 0 is, in practice, extremely expensive. In addition, the structure in which microlens arrays are bonded to both sides of one glass substrate is
It has the disadvantage of increasing the overall thickness.

[0011]

In order to solve the above problems, the present invention provides a translucent panel on the side on which the irradiation light of each of the three primary colors of a so-called transmissive color liquid crystal display element is incident. A flat plate type microlens array is formed by stacking, and a lens part for converging each irradiation light to each corresponding pixel electrode is formed in the first flat plate type microlens array separated from the liquid crystal layer, and the liquid crystal layer is formed. The second flat microlens array close to is formed with a lens portion that makes the direction of the principal ray of each irradiation light passing through each pixel electrode substantially parallel to the optical axis, and further includes the first and second flat microlens arrays. The thickness of the lens array is adjusted by polishing the side opposite to the lens portion forming surface, so that the lens forming surface of the first flat plate type microlens array and the polishing surface of the second flat plate type microlens array are joined together. did.

It is preferable that the pixel electrodes corresponding to these three primary colors are repeatedly arranged linearly and that the centers of the respective pixel electrodes of the three primary colors are within the area of one lens portion.

It is preferable that both the first and second flat plate type microlens arrays are made into a lens portion by forming a concave portion on the fire-making surface by etching and filling the concave portion with a high refractive index resin. . Here, the fired surface refers to the unpolished surface of the molten glass that has been gradually cooled and plated when the glass substrate is manufactured by the fusion method or the like.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a sectional view of a transmissive liquid crystal display device according to the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is an enlarged sectional view of an essential part of FIG.

The transmissive liquid crystal display element 1 is a translucent panel 2,
The transparent panel 2 located on the incident side of the irradiation light is formed by stacking the first and second flat plate type microlens arrays 6 and 7 on top of each other. ing.

That is, a black matrix layer of Cr or the like and a transparent conductive film of ITO or the like are formed on the surface of the translucent panel 2 (flat type microlens array 7), and an alignment film is further provided on the black matrix layer. TFT is provided on the opposite surface of the light-sensitive panel 3.
(Thin film transistor) and pixel electrodes are formed, these translucent panels 2 and 3 are combined to form a cell group, and finally liquid crystal is injected and sealed to complete the liquid crystal display element 1.

The first flat plate type microlens array 6 provided at a position apart from the liquid crystal 5 has a concave portion 9 formed on one surface of the glass substrate 8 by etching, and the concave portion 9 is filled with a high refractive index resin to form a lens. Part 10 is set. The second flat plate microlens array 7 provided near the liquid crystal 5 also has a concave portion 12 formed by etching on one surface of the glass substrate 11, and the concave portion 12 is filled with a high refractive index resin to form a lens portion 13. I am trying to become. Here, it goes without saying that the high-refractive-index resin should clear the weather resistance at the level of general household electrical appliances, and further, the temperature of the liquid crystal display element manufacturing process, that is, the transparent conductive film formation, the alignment film formation , Temperature of each process of cell set, about 150 to 2
Select one that can withstand 00 ° C.

The lens portions 10 and 13 of the first and second flat plate type microlens arrays 6 and 7 are provided corresponding to each other, and as shown in FIG.
In one region of 0 and 13, the pixel electrodes 3a are evenly arranged so that the centers of the pixel electrodes 3a are located at the vertices of the triangle. In this arrangement, as shown by the dotted line in the figure, red (R), blue (B),
The centers of the green (G) pixels are linearly arranged over a plurality of lens regions.

Regarding the arrangement of the lens portion and the pixels, as shown in FIG. 3, the red (R), blue (B), and green (G) pixels are linearly arranged and one lens portion 10, 1
3, or the contour shape of the lens portion may be square instead of hexagonal as shown in FIG.

Further, in the flat plate type microlens arrays 6 and 7, the thickness of the glass substrates 8 and 11 is adjusted by polishing so as to adjust the focal length and the like to a set value. The lens portions 10, 13 of the flat plate type microlens arrays 6, 7 are
In forming the pits, the glass substrates 8 and 11 are etched into the recessed portions 9 and 12 by etching on the non-polished fired surface.
Is formed, and the concave portions 9 and 12 are filled with a high refractive index resin to form the lens portions 10 and 13. Here, the recesses 9, 1
In addition to 2, an outer peripheral groove or the like is formed by etching at the same time, and if an extra high refractive index resin is received in this outer peripheral groove, an extra resin layer is hardly formed in the lens portion, and the lens surface is flattened. The property is significantly improved as compared with the conventional two-layer structure, which is extremely effective in producing a liquid crystal display element.

As described above, since the recesses 9 and 12 are formed by etching on the fire-polished surface (smooth surface), recesses are formed in conformity with the opening shape of the mask without unevenness. Due to the polishing, fine scratches (irregularities) 14 remain as shown in FIG. However, as shown in FIG. 5, when used by being filled with a high-refractive-index resin, it is easy to make fine scratches after polishing invisible to the extent used in a liquid crystal projector. Very low cost polishing grades are sufficient compared to the surface level used.

Specific dimensions and the like of the transmissive liquid crystal display device according to the present invention will be described below. (Example 1) LCD pixel pitch: 30 × 90 μm (90 × 90 μm RGB3
Pixels) Number of LCD pixels: 2400 × 600 (square array) LCD screen effective area: 72 × 54 mm Microlens pixel pitch: 90 × 90 μm (square dense array) Glass substrate (8,11): non-alkali glass, n = 1. 51 Glass substrate (8) thickness: 0.7 mm Glass substrate (11) thickness: 0.66 mm Curvature radius of etching recess: 66 μm (both first and second lenses) Refractive index of high refractive index resin: n = 1.66 (first Microlens focal length: f = 440 (both first and second lenses) (Example 2) LCD pixel pitch: 20 × 60 μm (60 × 60 μm RGB3
Pixels) Number of LCD pixels: 2400 × 600 (square array) LCD screen effective area: 48 × 36 mm Microlens pixel pitch: 60 × 60 μm (square dense array) Glass substrate (8,11): non-alkali glass, n = 1. 51 Glass Substrate (8) Thickness: 0.7mm Glass Substrate (11) Thickness: 0.44mm Curvature Radius of Etching Recess: 44 μm (Both First and Second Lens) High Refractive Index Resin Refractive Index: n = 1.66 Microlens focal length: f = 296 (both first and second lens)

[0023]

According to the present invention as described above,
The transmissive panel of the transmissive liquid crystal display element on the side where the irradiation light is incident is constructed by laminating the first and second flat plate microlens arrays, and the first flat plate microlens array separated from the liquid crystal layer is The irradiation light is focused on each pixel, and the second flat plate type microlens array close to the liquid crystal layer is set so that the directions of the chief rays are substantially parallel to each other. Can be kept small.

At this time, the thickness of the substrate between the first microlens array and the second microlens array is
It is possible to realize a low-cost two-layer microlens array, which can be easily mass-produced and can be easily manufactured to a desired value.

In particular, in a single-plate type color liquid crystal projector, for a transmissive liquid crystal display element of a type in which angles are made different for each of the three primary colors, incident light is assumed to be incident at an angle with respect to the optical axis. Therefore, the diffusion angle of the emitted light becomes large. However, by using the transmissive liquid crystal display element of the present invention, as shown in FIG. Separated for ease)
This is extremely effective because it can concentrate on the lens and reduce the diameter of the projection lens.

[Brief description of drawings]

FIG. 1 is a sectional view of a transmissive liquid crystal display element according to the present invention.

FIG. 2 is a view taken in the direction of arrows AA in FIG. 1;

FIG. 3 is a view similar to FIG. 2 showing another embodiment of the arrangement of the lens portion and the pixels.

FIG. 4 is a view similar to FIG. 2 showing another embodiment of the arrangement of the lens portion and the pixels.

5 is an enlarged cross-sectional view of the main part of FIG.

FIG. 6 is a diagram showing the spread of R, G, and B light beams on the projection lens.

FIG. 7 is an overall view of a conventional single-panel type color liquid crystal projector.

8 is a sectional view of a liquid crystal display element used in the projector of FIG.

FIG. 9 is a diagram showing the spread of R, G, and B light beams on the projection lens.

FIG. 10 is a cross-sectional view of a conventional liquid crystal display device to which a flat plate type microlens array in which lenses are formed on both surfaces of one glass substrate is applied.

FIG. 11 is a diagram illustrating a method of forming lenses on both surfaces of a glass substrate.

FIG. 12 is a diagram illustrating a method of forming lenses on both surfaces of a glass substrate as in FIG. 11.

FIG. 13 is a diagram pointing out problems when forming lenses on both surfaces of a glass substrate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Transmissive liquid crystal display element, 2, 3 ... Translucent panel, 4 ...
Gap, 5 ... Liquid crystal, 6, 7 ... Flat plate type microlens array, 8, 11 ... Glass substrate, 9, 12 ... Recessed portion, 10, 1
3 ... Lens part, 14 ... Fine scratches due to polishing.

Claims (3)

[Claims] 1. A liquid crystal layer provided between a pair of translucent panels is irradiated with irradiation light from one translucent panel side, and the irradiation light is irradiated to the other translucent panel side through a pixel opening. In a transmissive color liquid crystal display element that is adapted to emit light,
The translucent panel on the side where the irradiation light is incident has the first and second transmissive panels.
Of the flat plate type microlens array, the irradiation light beams of different wavelength regions are incident on the first flat plate type microlens array apart from the liquid crystal layer at different angles, and the pixels corresponding to the respective irradiation light beams are provided. A lens portion for condensing light is formed on the electrode, and a lens for making the direction of the principal ray of each irradiation light passing through each pixel electrode substantially parallel to the optical axis is formed in the second flat plate type microlens array near the liquid crystal layer. Part is formed,
Further, the thickness of the first and second flat plate type microlens arrays is adjusted by polishing the side surface opposite to the lens portion forming surface, and the lens forming surface of the first flat plate type microlens array and the second flat plate type microlens are adjusted. A transmissive color liquid crystal display device, characterized in that the polished surface of the array is bonded. 2. The transmissive color liquid crystal display device according to claim 1, wherein the irradiation light in the different wavelength ranges is irradiation light of three primary colors, and pixel electrodes corresponding to these three primary colors are linearly repeated. A transmissive color liquid crystal display element, which is arranged so that the centers of the respective pixel electrodes of the three primary colors fit within the area of one lens portion. 3. The transmissive color liquid crystal display element according to claim 1, wherein the flat plate type microlens array has a recess formed by etching on a fired surface of a glass substrate, and the recess has a high refractive index resin. A transmissive color liquid crystal display device, characterized in that a lens portion is formed by filling the same.