Optical: systems and elements – Single channel simultaneously to or from plural channels – By surface composed of lenticular elements
Reexamination Certificate
2000-10-17
2002-08-20
Epps, Georgia (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By surface composed of lenticular elements
C359S642000, C349S057000, C427S162000
Reexamination Certificate
active
06437918
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a planar micro-lens for use in a liquid crystal display element and so on, and relates to a planar micro-lens being characterized by the lens material thereof.
DESCRIPTION OF PRIOR ART
A liquid crystal display element is used in a projector television (PTV). In this liquid crystal display element, wherein a liquid crystal is put into a gap defined between two (2) pieces of glass plates, a TFT (thin film transistor) is formed from amorphous silicon and/or polysilicon, upon a surface of each of site glass plates facing to the liquid crystal, corresponding to each of pixels.
And, in the PTV using a penetrative type of liquid crystal display element therein, an illumination light is irradiated from a xenon lamp or a metal halide lamp, etc., upon the liquid crystal display element, so that it penetrate through pixel openings of the liquid crystal display element to an exit side, thereby projecting a picture or video image formed on the liquid crystal display element through a projection lens onto a screen.
For brightening the above-mentioned projection picture through collecting or condensing the above-mentioned illumination light onto the pixel openings, so as to increase the ratio of the illumination light penetrating through the liquid crystal display element, a planar micro-lens is connected or bonded on one of the two (2) pieces of glass substrates constructing the liquid crystal display element, at a side upon which the illumination light is incident, so that the illumination light is condensed onto the pixel openings, and a method for manufacturing such planar micro-lens is known, as is disclosed, for example, in Japanese Laid-Open Patent Hei 7-225303 (1995). Also, further methods are known, such as those disclosed in Japanese Laid-Open Patent Hei 2-42401 (199), Japanese Laid-Open Patent Hei 2-116809 (1990), and U.S. Pat. No. 5,513,289.
Explanation of the manufacturing method of the planar micro-lens disclosed in the Japanese Laid-Open Patent Hei 7-225303 is as below, explained with reference to to FIGS.
20
(
a
) through (
h
).
First, as shown in FIG.
20
(
a
), a light sensitive film is formed on a surface of the substrate, and an electron beam is irradiated on the light sensitive film so as to form the lens portion, as shown in FIG.
20
(
b
), thereby producing a master disc of the micro-lens array.
Next, as shown in FIG.
20
(
c
), upon the surface of the master disc of the micro-lens array is laminated nickel or the like through an electrocast method, and further, as shown in FIG.
20
(
d
), the laminated body is separated or removed from the master disc of the micro-lens array, thereby producing a stamper.
Then, as shown in FIG.
20
(
e
), an ultraviolet ray curable resin is poured into recess portions of the stamper, and as shown in FIG.
20
(
f
), it is extended while being pushed down by a transparent substrate, and further as shown in FIG.
20
(
g
), the ultraviolet ray curable resin is cured, and thereafter as shown in FIG.
20
(
h
), the ultraviolet ray curable resin is separated from the stamper together with the transparent substrate.
Then, upon the surface of the separated transparent substrate, on which the lens portions are formed from the ultraviolet ray curable resin, a cover glass is fitted to be bonded on it, by pouring an adhesive resin of low refraction index to be contained between the facing surfaces thereof, thereby forming the planar micro-lens.
The lens portions are formed by means of irradiating an electron beam upon a resist in the above-mentioned method, however it is difficult to form a microscopic lens by this method with high precision or accuracy.
Also, for the planar micro-lens to be installed within a liquid crystal display device, it is desirable to be of a dense type, in which a large number of the lens portions are aligned closely without gaps between them in the plane view thereof, however it is difficult to produce such the dense micro-lens array through such a conventional manufacturing method as that mentioned above.
Further, for manufacturing the liquid crystal display device, it is also necessary to form elements or components such as transparent electrodes, an orientation film, a black matrix, etc., on a surface of the above-mentioned cover glass facing to the liquid crystal. Since the steps for the forming of those elements must be conducted under heating, it is therefore determined that resin materials forming the lens and the adhesive layers should not be such ones that may be subject to thermal cracking and/or thermal deformation and decreases of transparency thereof, and in the Japanese Laid-Open Patent Hei 7-225303 (1995) are listed various materials being commercially available for use as resins heat-resistant against temperatures of 150° C. or more. However, in actual practice, by taking the temperature for forming the transparent electrodes and the orientation film with a spattering method, etc., into consideration, heat-resistance against 150° C. or more is not great enough resistance, since there can be easily caused a change of color (i.e., transparent material changed in color to yellow), separation, cracks, dimness, etc., therefore at least a heat-resistance to temperatures of 180° C. or more is required for the resin material having high refraction index, which is used as the lens portion in particular.
DISCLOSURE OF THE INVENTION
In accordance with the present invention, for dissolving such problems of the conventional arts as those mentioned above, a first object is to provide a method for manufacturing a planar micro-lens, with which microscopic lens portions can be formed on the surface of a glass substrate with high precision or accuracy, and a second object is to provide a planar micro-lens having a superior hear-resistance thereof.
For achieving the first object, according to the present invention, there are provided methods relating to the present claims 1 through 3, assuming that each of them is based upon a method for manufacturing a planar micro-lens, having a high refractive index resin material and a low refractive index resin material, being laminated in layers within a region defined between a first glass substrate and a second glass substrate, wherein microscopic spherical surfaces or microscopic cylindrical surfaces are aligned on a boundary surface of the two kinds of the resin materials in a single dimension or two dimensions, wherein the method for manufacturing a planar micro-lens defined in claim
1
comprises the following first through sixth steps:
(First step)
a step for forming a large number of microscopic recess portions forming cylindrical or spherical surfaces on a surface of a glass substrate in a single dimension or two dimensions, by conducting a wet etching through a mask upon the surface of the glass substrate as a forming die;
(Second step)
a step for aligning the large number of the microscopic recess portions densely, by again conducting the wet etching upon the surface of the glass substrate as the forming die on which the microscopic recess portions are formed in the first step, but not through the mask;
(Third step)
a step for applying a separating agent upon the surface of the glass substrate as the forming die having the microscopic recess portions aligned densely being formed in the second step, and further for applying a light-curable or heat-curable resin material of high refractive index thereon;
(Fourth step)
a step for curing the high refractive index resin material, after piling a first glass substrate upon the high refractive index resin material which is applied to the glass substrate as the forming die in the third step, so as to cause the high refractive index resin material to extend on the surface thereof;
(Fifth step)
a step for separating the high refractive index resin material which is cured in the fourth step and the first glass substrate from the glass substrate as the forming die, and for applying a low refractive index resin material on the high refractive index r
Arai Daisuke
Hamanaka Kenjiro
Hirayama Naoto
Kishimoto Takashi
Matsuda Atsunori
Epps Georgia
Merchant & Gould P.C.
Nippon Sheet Glass Co. Ltd.
Spector David N.
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