Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-10-22
2002-11-05
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S138000, C349S110000
Reexamination Certificate
active
06476890
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display apparatus, in particular, to a liquid crystal display apparatus provided with an effective function for reflective color displaying.
A conventional reflective color liquid crystal display apparatus, which comprises a reflector provided on many micro-protrusions formed of resin, is disclosed in JP-A-4-243226 (1992). A color filter for reflective color liquid crystal display apparatus is disclosed in JP-A-6-230364 (1994) and others. The color filter does not make any trouble in driving liquid crystal, even if an optical reflector composing a reflector causes an electrical short circuit with transparent electrodes via a defect of color filter, by patterning the reflector to a shape approximately as same as the shape of the color filter.
In accordance with the prior art, a reflector comprising many fine protrusion-depression reflecting planes, whereon circular protrusions or depressions are arranged irregularly so as not to generate optical interference, is disclosed.
Furthermore, as disclosed in JP-A-10-177106 (1998), a liquid crystal display apparatus; wherein liquid crystal element comprises a reflector, which is made to collect incident light in a specified direction by forming circular protrusions or depressions having unsymmetrical distribution of slope angles in their cross section shape; has been proposed.
SUMMARY OF THE INVENTION
In accordance with the prior art described above, any black matrix becomes unnecessary, because the liquid crystal driving does not cause any trouble, even if an optical reflecting film composing a reflector causes an electrical short circuit with transparent electrodes via a defect of color filter, by patterning the reflector to a shape approximately as same as the shape of the color filter, and unnecessary reflection light from unopened portion can be prevented. However, the color filter for reflective color liquid crystal display apparatus had such a problem that contrast was decreased with an element structure having no black matrix layer depending on display mode (for instance, normally open mode), because the color filter for reflective color liquid crystal display apparatus must have spectral characteristics utilizing positively the light in a certain wavelength region, which should be shielded naturally.
Because a liquid crystal layer having an uniform thickness could not be formed with the composition of the prior art described above, wherein only a color filter layer was formed on a surface-roughened reflector, the color filter had additionally such problem that a quality of display (brightness and contrast) was decreased.
In accordance with the prior art, if a leveling layer was provided onto the color filter layer for forming a liquid crystal layer having an uniform thickness, a problem such as decreasing the brightness and others were generated.
The prior art had a problem that display was dark, because, in order to prevent coloring caused by optical interference by arranging circular protrusions or depressions irregularly in a region corresponding to pixel electrode portions, the number of protrusions or depressions, which were reflecting elements for controlling incident light, was decreased significantly from a case when the protrusions or depressions were arranged in a closest packing manner.
In accordance with the prior art, reflected light was collected in a specified direction by making the slope angle distribution of the circular protrusions or depressions unsymmetrical. Therefore, there was a problem such as difficulty in controlling the shape of the fine protrusion or depression, because the manufacturing process became complex.
Furthermore, in accordance with the prior art, fine circular protrusions or depressions were formed by a photolithography method. Therefore, there was a problem such as a high cost, because the manufacturing process was complex, and the number of manufacturing steps was large.
The object of the present invention is to provide a liquid crystal display apparatus comprising a reflector having preferable reflecting characteristics by solving the above described problems, and to provide a manufacturing method thereof.
As a first means for achieving the above object, the reflective color liquid crystal display apparatus of the present invention uses the following liquid crystal display element:
The liquid crystal display element comprises an electrode substrate: wherein a reflector composed of a metal such as aluminum, silver, and others, is formed on many fine protrusions and depressions formed with a resin, wherein a black pigment having light shielding function is dispersed, on a glass substrate corresponding to apertures: color filters of red, green, and blue having leveling function are formed on the reflector; and transparent electrodes and alignment layer are formed on the color filters: and another electrode substrate: wherein transparent electrodes and alignment layer are formed on a glass substrate: the liquid crystal display element is manufactured by matching the electrode substrates via a spacing material for defining thickness of the liquid crystal so that each of the alignment layers are faced each other, filling liquid crystal into the interval between the electrode substrates by any method such as vacuum filling method and the like, and sealing the interval.
As a second means for achieving the above object, the reflective color liquid crystal display apparatus of the present invention is a reflective color liquid crystal display apparatus comprising a reflector composed by laminating a polymer layer having protrusions and depressions and a reflective layer onto a glass substrate: the reflector comprises the polymer layer, whereon fine protrusion-depression planes are formed by the following method and the like in order to achieve the above object:
1) string shaped protrusions having smooth curves, or string shaped depressions are arranged continuously and alternately,
2) string shaped protrusions having smooth curve are arranged continuously, and
3) string shaped depressions having smooth curve are arranged continuously.
In accordance with the reflector of the reflective liquid crystal display apparatus of the present invention, fine protrusion-depression planes are formed on the polymer layer by arranging the string shaped protrusions or the string shaped depressions in a manner that the slope angle distribution of the cross section shapes of the depressions and depressions in a direction at a right angle to the longitudinal direction is approximately symmetrical from right and left, and total lengths of the respective string shaped protrusions or string shaped depressions in respective directions are approximately equal.
In accordance with the reflector of the reflective liquid crystal display apparatus of the present invention, fine protrusion-depression planes are formed on the polymer layer by arranging the string shaped protrusions or the string shaped depressions in a manner that the slope angle distribution of the cross section shapes of the depressions and depressions in a direction at a right angle to the longitudinal direction is approximately symmetrical from right and left, and total lengths of the respective string shaped protrusions or string shaped depressions in respective directions differ each other.
The reflective liquid crystal display apparatus of the present invention is featured in having an element structure; wherein an electrode substrate comprising a polymer layer, which comprises the fine protrusion-depression planes composed of the string shaped protrusions and string shaped depressions, a reflective layer, an insulating layer, transparent electrodes, and an alignment layer laminated on a glass substrate; and another electrode substrate comprising a black matrix layer, color filters, a leveling layer, transparent electrodes, and an alignment layer are laminated on a glass substrate; are arranged so that the transparent electrodes of the above respective electrode substrates
Abe Makoto
Funahata Katsuyuki
Itou Osamu
Komura Shinichi
Kondo Katsumi
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
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