Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2002-08-16
2004-10-12
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
Reexamination Certificate
active
06803980
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 producing a reflective color display.
A conventional reflective color liquid crystal display apparatus, which comprises a reflector provided with many micro-protrusions formed of resin, is disclosed in JP-A-4-243226 (1992). A color filter for a reflective color liquid crystal display apparatus is disclosed in JP-A-6-230364 (1994) and other publications. The color filter will not create any problems in the driving of a liquid crystal, such as when an optical reflector causes an electrical short circuit with transparent electrodes via a defect in the color filter, if the reflector is patterned to a shape approximately the same as the shape of the color filter.
A reflector comprising many fine protrusion-depression reflecting planes, whereon circular protrusions or depressions are arranged irregularly so as not to generate optical interference, has been proposed.
Furthermore, JP-A-10-177106 (1998) discloses a liquid crystal display apparatus, in which a 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 sectional shape.
SUMMARY OF THE INVENTION
In accordance with the prior techniques described above, the use of a black matrix becomes unnecessary, because the liquid crystal driving will not create any problems, such as when an optical reflecting film forming a reflector causes an electrical short circuit with transparent electrodes via a defect of a color filter, if the reflector is patterned to a shape approximately the same as the shape of the color filter, and so unnecessary reflection of light from an unopened portion can be prevented. However, the color filter for a reflective color liquid crystal display apparatus has a problem in that contrast is decreased with an element structure having no black matrix layer, depending on the display mode (for instance, normally open mode), because the color filter for a reflective color liquid crystal display apparatus must have spectral characteristics positively utilizing the light in a certain wavelength region, which should be shielded naturally.
Because a liquid crystal layer having a uniform thickness could not be formed with the composition of the liquid crystal display devices described above, wherein only a color filter layer was formed on a surface-roughened reflector, the color filter had an additional problem in that the quality of display (brightness and contrast) was decreased.
In accordance with the prior liquid crystal display devices, if a leveling layer was provided on the color filter layer for forming a liquid crystal layer having an uniform thickness, a problem, such as a decrease of the brightness, and other problems were generated.
The prior liquid crystal display devices had a problem in that the 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 in which the protrusions or depressions were arranged in a closely packed manner.
In accordance with the prior liquid crystal display devices, 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 protrusions or depressions, because the manufacturing process became complex.
Furthermore, in accordance with the prior liquid crystal display devices, fine circular protrusions or depressions were formed by a photolithography method. Therefore, there was a problem, such as a high cost of manufacture, 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 method of manufacture 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 construction.
The liquid crystal display apparatus comprises an electrode substrate, wherein a reflector composed of a metal, such as aluminum, silver, and the like, is deposited on many fine protrusions and depressions formed on a resin layer, wherein a black pigment having a light shielding function is dispersed, and the resin layer is disposed on a glass substrate. Color filters of red, green, and blue having a leveling function are formed on the reflector; and transparent electrodes and an alignment layer are formed on the color filters. The liquid crystal display apparatus has another electrode substrate, wherein transparent electrodes and an alignment layer are formed on a glass substrate. The liquid crystal display apparatus is manufactured by joining the electrode substrates via a spacing material for defining the thickness of the liquid crystal so that each of the alignment layers face each other, filling liquid crystal into the interval between the electrode substrates by any method such as a 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 has 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 a smooth curve are arranged continuously; and
3) string-shaped depressions having a smooth curve are arranged continuously.
In 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 such a manner that the slope angle distribution of the cross sectional 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 the total lengths of the respective string-shaped protrusions or string-shaped depressions in respective directions are approximately equal.
In 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 such a manner that the slope angle distribution of the cross section shapes of the depressions, and the depressions in a direction at a right angle to the longitudinal direction, is approximately symmetrical from right and left, and the total lengths of the respective string-shaped protrusions or string-shaped depressions in respective directions differ from each other.
The reflective liquid crystal display apparatus of the present invention is featured in having an electrode substrate formed by a polymer layer, which comprises fine protrusion-depression planes composed of 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 e
Abe Makoto
Funahata Katsuyuki
Itou Osamu
Komura Shinichi
Kondo Katsumi
Hitachi , Ltd.
Parker Kenneth
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