Optics: measuring and testing – By alignment in lateral direction – With light detector
Reexamination Certificate
2002-01-22
2004-12-07
Toatley, Jr., Gregory J. (Department: 2877)
Optics: measuring and testing
By alignment in lateral direction
With light detector
C430S320000, C425S374000, C264S001600, C264S002200, C428S148000
Reexamination Certificate
active
06829050
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical device provided with a thin resin film having a micro-asperity pattern, a manufacturing method, and an apparatus of the optical device.
2. Description of the Related Art
Nowadays, liquid crystal display devices are increasingly applied to personal computers, TV receivers, word processors, video equipment, etc. To increase the functionality and reduce the size, power consumption, cost, etc. of such electronic equipment, reflection-type liquid crystal display devices are being developed that display an image by reflecting external light instead of using a backlight.
FIG. 15
shows an example of such reflection-type liquid crystal display devices. A reflection plate
1
is disposed under a counter substrate
28
that is composed of a transparent electrode facing a liquid crystal layer
27
, a color filter layer formed over the transparent electrode, and a surface glass substrate disposed over the color filter layer. The reflection plate
1
is used to increase the viewing angle of image display of the liquid crystal display device by diffuse-reflecting light coming from the counter substrate
28
.
For example, reflection plates used in such reflection-type liquid crystal display devices are formed by the following melting method. A photosensitive resin material is applied, by spin coating or the like, to the surface of a glass or resin substrate or the surface of a structure in which TFT transistors, liquid crystal driving elements, etc. are formed on such a substrate. The photosensitive resin layer is processed by photolithography so as to have asperities that are generally rectangular in cross-section, and then it is subjected to a heat treatment, whereby a smooth surface is formed by surface tension etc.
A roll embossment method is also known. In this method, a melted resin is applied to the surface of a micro-asperity pattern stamper that is provided on the outer circumferential surface of an embossment roll. As the resin sheet formed with an asperity pattern is cooled and set and also pealed off the stamper surface, it is contact-bonded to the surface.
Incidentally, a method for manufacturing an ideal micro-asperity pattern is required to satisfy the following and other conditions: 1) various three-dimensional shapes can be formed and arranged regularly or randomly; 2) a surface shape is not made obtuse by heating and the processing accuracy is high; 3) a thin film having a uniform planar shape can be formed; 4) a wide selection range of resin materials is available; 5) the cycle time is short and the mass-productivity is high.
The melting method can easily form a thin film because a resin is formed on a substrate by spin coating. However, since the melting method makes use of the phenomenon that a surface shape of a resin layer is made obtuse by a heat treatment, it cannot realize acute angles nor long planar shapes. It can realize only a narrow variety of three-dimensional shapes.
The melting method has additional problems. Since the melting conditions depend on the asperity shape that is formed by photolithography, the shape dispersion tends to be large and the processing accuracy is low. A number of manufacturing steps are needed and hence the cycle time is long. The degree of freedom of selection of photosensitive materials is low.
In the roll embossment method, since the resin application step and the transfer step can be combined into a single step, the cycle time of formation of a micro-asperity pattern is short. Since the stamper is produced in advance, a desired three-dimensional shape can be realized accurately in a stable manner. Any resin material can be used as long as it is meltable; that is, the degree of freedom of selection of resin materials is high. However, the thickness of a resin sheet is one order greater than in the melting method; it is difficult to form a thin film that is as thin as several micrometers.
In reflection-type liquid crystal display devices, no backlight is used and a reflection layer is formed on an asperity pattern layer to introduce external light to a liquid crystal layer. A reflection film having the asperity pattern layer is disposed under color filters enclosed by a block matrix, and liquid crystal driving elements are disposed between the reflection film and the color filter layer or under the reflection film.
If a registration error occurs between the color filter layer and the asperity pattern, light that should enter one of R, G, and B color filters may enter a color filter adjacent to it or a sufficient quantity of light may not enter color filters because of interruption by the black matrix, as a result of which a moire may occur and lower the legibility. If a registration error occurs between the color filter layer and the liquid crystal driving elements, intended liquid crystal portions cannot be driven and hence an intended image cannot be formed.
To avoid the above problems, the reflection film having the asperity pattern is provided with asperity pattern layer alignment marks and the liquid crystal driving elements are disposed by using those alignment marks as references. On the other hand, the color filter layer is provided with filter layer alignment marks. The reflection layer and the color filter layer are registered with each other by locating the two kinds of alignment marks at the same positions.
However, conventionally, as shown in
FIGS. 23A-23C
, the liquid crystal driving elements
31
are disposed in two ways: under the reflection film
26
(see FIG.
23
B); and over the reflection film
26
(see FIG.
23
C).
In the arrangement shown in
FIG. 23B
, since the liquid crystal driving elements
31
are disposed under the reflection layer
26
, to perform registration between the reflection layer
26
and the color filter layer
35
it is necessary to remove parts of the asperity pattern layer
4
corresponding to the alignment marks
22
and thereby enable visual or optical detection of the alignment marks
22
.
In the arrangement shown in
FIG. 23C
in which the liquid crystal driving elements
31
and the alignment marks
22
are disposed on a transparent planarization layer
45
, it is necessary to form the planarization layer
45
separately, to dispose the alignment marks
22
on the surface of the planarization layer
45
so as to correspond to respective alignment marks
4
a
of the asperity pattern layer
4
, and dispose the liquid crystal driving elements
31
also on the surface of the planarization layer
45
. This results in a problem that the number of members and manufacturing steps are large.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above circumstances in the art, and an object of the invention is therefore to provide an optical device having an asperity pattern that can be formed as a thin film with high accuracy in any of various three-dimensional shapes, as well as to provide a manufacturing method and apparatus of such an optical device. In this specification, “micro-asperity pattern” is a generic term of asperity shapes that develop one-dimensionally or two-dimensionally and is 0.1 &mgr;m to hundreds of micrometers in depth and arbitrary in width, length, and shape. Also, “reflection-type liquid crystal display device” is a generic term of devices in which a liquid crystal is sealed between a transparent counter substrate having a transparent electrode and an active matrix substrate having a reflection surface that is provided with a surface micro-asperity pattern.
The invention provides a manufacturing method of an optical device, comprising the steps of preparing a cylindrical die unit an outer circumferential surface of which is formed with a micro-asperity pattern; preparing a substrate that is coated with a thin resin film; holding the substrate by a transfer stage; and forming a micro-asperity pattern on the thin resin film by pressing the outer circumferential surface of the die unit against the thin resin film with pressurizing means while rolling th
Aoyama Shigeru
Funamoto Akihiro
Ikeda Masaaki
Matsushita Motohiko
Lauchman Layla
Omron Corporation
Osha & May L.L.P.
Toatley , Jr. Gregory J.
LandOfFree
Optical device provided with a resin thin film having a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical device provided with a resin thin film having a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical device provided with a resin thin film having a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3305498