Optical: systems and elements – Glare or unwanted light reduction – Directional or angular discrimination
Reexamination Certificate
1999-10-25
2001-03-13
Sikder, Mohammad Y. (Department: 2872)
Optical: systems and elements
Glare or unwanted light reduction
Directional or angular discrimination
C359S614000, C359S599000
Reexamination Certificate
active
06199989
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an optical plate that can realize high transmittance and reflectance.
BACKGROUND OF THE INVENTION
In recent years, liquid crystal displays have been used for various apparatuses such as electronic personal organizers, personal digital assistants, amusement apparatuses and portable telephones in addition to notebook type word processors and personal computers. Of these, portable apparatuses frequently use transflective liquid crystal displays. The transflective liquid crystal displays are used as reflective displays using natural light or indoor light (hereinafter, referred to as reflecting condition) in the daytime and under well-lighted conditions, and are used as transmissive displays using backlights (hereinafter, referred to as transmitting condition) in the nighttime and under low light conditions. As a transflective liquid crystal display, it is known that a display comprises a first polarizer, liquid crystal cells (TN cells and STN cells), a second polarizer, a transflective plate and a backlight unit.
As a transflective plate used in these displays, it is known that a display achieves both a reflecting function and a transmitting function by dispersing inorganic particles having high refractive index such as pearl mica into a matrix, causing light to be reflected at the particles in the reflecting condition and causing light to be transmitted through the gap among the particles in the transmitting condition.
Japanese Laid-open Patent Application No. 55-103583 describes a reflecting transmitting member having a pattern in which parts that reflect light and parts that transmit light are alternately arranged.
Japanese Laid-open Patent Application No. Sho 55-46707 discloses a transflective polarizer in which transparent and/or semitransparent particles such as aluminum oxide, titanium oxide, aluminum, tin, gold or silver are uniformly dispersed in an adhesive material layer.
However, in a case where the conventional transflective plates are laminated to polarizers with a pressure-sensitive adhesive and attached to reflective liquid crystal displays and the displays are driven, both brightness and viewability are not always sufficient.
FIG. 1
is a view illustrative of the principle of a conventional transflective plate in which inorganic particles having high refractive index such as pearl mica or particles having high reflectance such as a metal are dispersed in a matrix. In
FIG. 1
, the downside corresponds to the backside, and the upside corresponds to the viewer's side. As shown in
FIG. 1
, since substantially only the light leaking through the gap among the particles is used when the display is used in the transmitting condition because of the presence of the light component coming from the backside and being reflected at the inorganic particles or the metal particles to return to the backside, the light use efficiency is inferior, so that the transmittance cannot be increased. That is, to obtain high transmittance, it is necessary to decrease the particle content or increase the transmittance, so that the reflectance decreases. To increase the reflectance, it is necessary to increase the particle content or increase the reflectance (the transmittance decreases), so that the transmittance decreases.
An object of the present invention is to provide an optical plate having high transmittance and high reflectance, and a transflective plate and a transflective light guide with which excellent brightness and viewability are obtained when attached to a transflective liquid crystal display and the display is driven.
SUMMARY OF THE INVENTION
The present inventors have intensively studied to solve the above-mentioned problems, and have found that an optical plate having high reflectance in the reflecting condition, high transmittance in the transmitting condition by effectively using the reflected light and excellent brightness and viewability can be obtained in both of the conditions by providing a light reflecting layer having a specific shape, and have completed the present invention.
That is, the present invention provides an optical plate having both a light reflecting function and a light transmitting function comprises
a layer comprising convex members which are arranged inside or on a surface of the optical plate so that a tip of the convex portion faces a backside of the optical plate,
a gap having a transmitting function which is formed between the convex members, and
a reflecting layer which is arranged on an outer surface of the convex portion, and on a base or an inner surface of the convex portion,
wherein said convex members, said gap and said reflecting layer are arranged so that a part of light ray from the backside directly passes through the gap between the convex members, that apart of remaining light ray is reflected at least one time at the reflecting layer on the outer surface of the convex portion and passes through the gap having a transmitting function formed between the convex members to come out from a surface of the optical plate, and that a part of incident light ray from the surface side is reflected at the reflecting layer on the base or the inner surface of the convex portion to come out from a surface of the optical plate.
REFERENCES:
patent: 5467417 (1995-11-01), Nakamura et al.
patent: 5521725 (1996-05-01), Beeson et al.
patent: 5797668 (1998-08-01), Kojima et al.
patent: 2 437 633 (1980-04-01), None
patent: 55-46707 (1980-04-01), None
patent: 55-103583 (1980-08-01), None
patent: 6-194653 (1994-07-01), None
patent: 9-73083 (1997-03-01), None
patent: 9-222516 (1997-08-01), None
patent: 10-10526 (1998-01-01), None
patent: 10-73725 (1998-03-01), None
Fujisawa Koichi
Maeda Yasuteru
Miyazaki Susumu
Sikd-er Mohammad Y.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Sumitomo Chemical Company Limited
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