Optical: systems and elements – Single channel simultaneously to or from plural channels – By surface composed of lenticular elements
Reexamination Certificate
2003-06-04
2004-08-24
Epps, Georgia (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By surface composed of lenticular elements
C359S620000, C359S622000, C264S001700, C216S026000
Reexamination Certificate
active
06781762
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a method of manufacturing a microlens which constitutes, for example, a microlens array plate suited for application to an electrooptic device, such as a liquid crystal device. The invention further relates to a microlens manufactured by the manufacturing method, a microlens array plate, an electrooptic device including the microlens, and an electronic equipment including the electrooptic device.
2. Description of Related Art
In a related art electrooptic device, such as a liquid crystal device, various wiring lines, such as data lines, scanning lines and capacitance lines, and various electronic elements, such as thin film transistors (hereinbelow “TFTs”) or thin film diodes (hereinbelow “TFDs”), are formed within an image display area. In each pixel, therefore, a region through or from which light capable of actually contributing to display is transmitted or reflected is essentially limited due to the existence of the various wiring lines and electronic elements, etc. Specifically, regarding each pixel, the opening rate of each pixel as is the rate of a region through or from which light actually contributing to display is transmitted or reflected (that is, the aperture region of each pixel), to the whole region, is about 70%, for example. Illumination source light or external light which is entered into the electrooptic device mostly includes parallel light rays, at least, when passing through an electrooptic substance layer, such as a liquid crystal layer, within the electrooptic device. However, in a case where parallel light rays have been entered into the electrooptic device, only that part of the whole quantity of light which is proportional to the opening rate of each pixel can be utilized without any contrivance.
Therefore, in the related art, a microlens array which includes microlenses corresponding to the respective pixels can be formed in an opposite substrate, or a microlens array plate can be stuck on an opposite substrate. Due to such microlenses, light rays which ought to progress toward the non-aperture regions of the respective pixels except the aperture regions thereof without the microlenses are collected in pixel units, so as to be guided into the aperture regions of the respective pixels when they are transmitted through the electrooptic substance layer. As a result, a bright display is realized by utilizing the microlens array in the electrooptic device.
The manufacture of this type of related art microlens is provided as stated below. First, a mask which is provided with a pit at a position corresponding to the center of the microlens to be formed is formed on, for example, a transparent substrate. Subsequently, the transparent substrate is subjected to wet etching through the mask, to thereby excavate a spherical recess which defines the curved surface of the microlens. Thereafter, the mask is removed, and the recess is filled up with a transparent medium of high refractivity. Thus, the microlens is formed in which a hemispherical recess centering around the pit having been first provided in the mask is included as a lens spherical surface. The microlens array can be manufactured by forming a large number of such microlenses in the shape of an array.
In the case of this type of microlens, it is important as basic requirements to enhance a lens efficiency and further to diminish spherical aberration.
According to the related art method of manufacturing the microlens as stated above, however, a non-spherical lens cannot be manufactured, although a spherical lens can be manufactured, comparatively easily.
In this regard, in order to manufacture the non-spherical lens, the related art includes a complicated and high-degree manufacturing method, for example, one in which a non-spherical recess is formed from a separate material on a substrate and is thereafter transferred onto the side of the substrate, or one in which a substrate is subjected to a plurality of different etching steps stage by stage. Such a manufacturing method, however, is basically difficult and increases manufacturing costs as well as reduces an available percentage. Further, there occurs the problem that, as manufacturing steps become complicated and high in degree, controlling the degree of non-sphericalness in the non-spherical lens becomes technically very difficult.
SUMMARY OF THE INVENTION
The present invention addresses or solves the above and/or other problems, and provides a method of manufacturing a microlens that is capable of manufacturing the non-spherical microlens comparatively easily. The invention also provides the microlens which is manufactured by the manufacturing method, an electrooptic device which includes the microlens, and an electronic equipment which includes the electrooptic device.
In order to address or solve the above, a method of manufacturing a microlens according to the present invention includes: forming on a substrate a first film an etching rate of which for a predetermined kind of etchant differs from that of the substrate; forming on the first film a mask in which a pit is provided at a position corresponding to a center of the microlens to-be-formed; and performing wet etching through the mask, to thereby excavate in the substrate a non-spherical recess which defines a curved surface of the microlens.
In accordance with the method of manufacturing a microlens according to the present invention, first of all, the substrate, for example, a quartz substrate or a glass substrate is formed thereon with the first film the etching rate of which for the predetermined kind of etchant, for example, one of hydrofluoric acid type differs from that of the substrate. Such a first film is formed by, for example, CVD (Chemical Vapor Deposition) or sputtering. Subsequently, the mask in which the pit is provided at the position corresponding to the center of the microlens to-be-formed is formed on the first film. Such a mask may well be formed in such a way, for example, that a second film is formed on one surface of the first film by CVD, sputtering or the like, whereupon it is patterned by photolithography and etching so as to provide the pit. Alternatively, the mask may well be formed directly on the region of the first film except the pit. Thereafter, the first film and the substrate are wet-etched through such a mask. The etching rates for the etchant employed here differ from each other between the first film and the substrate. Therefore, before the etching penetrates through the first film, a spherical recess is excavated in the part of the first film around the pit, by the wet etching which has no directionality. After the penetration, however, a non-spherical recess is excavated because the degree to which the first film is etched and the degree to which the substrate is etched are different from each other.
Thereafter, the non-spherical microlens can be manufactured comparatively easily by utilizing the curved surface which the non-spherical recess thus excavated defines. By way of example, it is permitted to manufacture the non-spherical micro lens by making the substrate a transparent one and filling up the recess with a transparent medium. Alternatively, it is permitted to manufacture the non-spherical microlens by utilizing the recess as a mold. Further, it is permitted to manufacture the microlens being a biconvex lens, by preparing two substrates, each of which is formed with such a microlens, and then sticking them to each other.
In an aspect of the method of manufacturing a microlens according to the present invention, the first film is higher in the etching rate than the substrate.
In accordance with this aspect, due to the etching, the recess in the shape of a pan whose bottom is shallower than a hemisphere is excavated in the substrate unlike in the first film which is higher in the etching rate than the substrate.
In another aspect of the method of manufacturing a microlens according to the present invention, the substrate is made of a transparent substrate; a
Dinh Jack
Seiko Epson Corporation
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