Optical: systems and elements – Single channel simultaneously to or from plural channels – By surface composed of lenticular elements
Reexamination Certificate
1998-12-07
2001-11-27
Mack, Ricky (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By surface composed of lenticular elements
C359S454000
Reexamination Certificate
active
06324011
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a reflection plate having directivity and a display apparatus using the same.
Conventionally, a reflection type display apparatus uses light taken in from external light as illumination light for a display panel and comprises a transmission type display panel
81
such as a liquid crystal display unit or the like which performs display by controlling transmission of light, and a diffusion reflection plate
82
opposed to the back surface of the display panel
81
, as shown in FIG.
21
.
In this reflection type display apparatus, external light such as natural light or room light entering from the front side of the display panel
81
is reflected by the diffusion reflection plate
82
and reflection light therefrom is used to illuminate the display panel
81
from its back side thereby to perform display. The external light entering from the front side is transmitted through the display panel
81
and is reflected by the diffusion reflection plate
82
, as indicated by an arrow in the figure. The light thus diffused within a wide range enters into the display panel
81
from its back surface and is emitted to the front side of the display panel
81
.
In general, in order to take in external light mainly from the upper edge of the screen, the reflection type display apparatus of the kind described above is used such that the direction inclined toward the upper edge of the screen (toward the left side in
FIG. 21
) with respect to the direction vertical to the screen is oriented in the direction from which brighter external light is obtained. The display is viewed from about the front surface direction which is close to the direction vertical to the screen or from about the direction which is inclined toward the lower edge of the screen from the vertical direction.
The conventional reflection type display apparatus using the diffusion reflection plate
82
has a problem that the display is dark. This is because the light reflected by the diffusion reflection plate
82
is widely diffused in directions which do not enter into the display panel
81
and the portion of the reflection light which can be used as illumination light is only the portion of light within a diffusion range within which light enters into the display panel
81
. Therefore, the amount of light which enters into the display panel
81
decreases. Further, the. spreading angle of light which is transmitted through the display panel
81
and emitted to the front side is large, so that the brightness of light emitted in the observation angle in which the display is viewed is low.
Display on a display apparatus is normally observed directly from the front side, as described above. In a conventional reflection type display apparatus, the spreading angle of light emitted to the front side of the display panel
81
is large, and only the portion of light emitted directly in the front direction is observed by an observer, and the other portion of the light emitted in oblique directions is not substantially observed by the observer. Therefore, actually observed display is dark as described above.
In case where a mirror reflection plate is used in place of the diffusion reflection plate
82
, regular reflection light reflected by the mirror reflection plate is emitted strongly in a specific direction at an angle symmetrical to the incidence angle with respect to the normal line of the reflection plate. However, since the intensity of light emitted in the direction toward the observer of the display panel
81
is weak, display is dark. In addition, since the reflection plate has a mirror structure, the surface distribution of the intensity of the reflection light is not uniform. Further, an environmental background view including the face of the observer and interior illumination devices is reflected on the display.
BRIEF SUMMARY OF THE INVENTION
The present invention has an object of providing a reflection plate having directivity, which is capable of sufficiently brightening display observed in a direction from an observer, and a display apparatus using the reflection plate.
In order to achieve the above object, the reflection plate having directivity according to a first aspect of the present invention comprises: a reflection film including a flat reflection surface; and an optical film having a first optical surface provided on the reflection surface and inclined in a first direction with respect to a normal line of the reflection surface thereby to reflect or refract light entering thereinto, second optical surfaces inclined in a second direction opposite to the first direction thereby to reflect or refract light entering thereinto, and a front surface into which external light enters and from which reflected light from the reflection surface and reflection light and/or refracted light from the first and second optical surfaces are emitted.
In the reflection plate having directivity according to the first aspect, incidence light which has entered within a wide angle range is emitted within a narrower angle range than the incidence angle range of the incidence light, by the reflection surface which reflects the incidence light as light having a strong light intensity in a predetermined direction, by reflection of light and a refraction effect inside the optical film, and by a strong reflection effect of the reflection surface.
This reflection plate may be provided such that the front surface (or emission surface) of the optical film is substantially parallel to the reflection surface of the reflection film.
Also, the first and second optical surfaces may be respectively arranged at inclination angles different from each other with respect to the normal line of the reflection surface of the reflection film. As a result of this, incidence light can be more effectively converged and emitted into the observation direction of from an observer.
The first and second optical surfaces may be provided to cross each other and grooves each having a triangular cross-section are formed in a side of a back surface of the optical film. Or, another third optical surface which crosses the first and second optical surfaces may be provided and a groove having a rectangular cross-section (which is substantially a trapezoid) may formed in the back surface side of the optical film.
A substance having a lower refraction ratio than the optical film may occupy the insides of the grooves having the triangular cross-section and the rectangular cross-section. As a result of this, the refraction effect or the reflection effect depending on the optical surfaces may be ensured.
By comprising the third optical surface, this third optical surface may be provided at a small angle with respect to the reflection surface, and therefore, much more reflection light from the reflection surface can be guided to the direction toward the front surface of the optical film.
The third optical surface should be preferably provided to be substantially parallel to the reflection surface of the reflection film. As a result of this, grooves each having a substantially trapezoidal cross-section may be formed in the back surface side of the optical film, by the first to third optical surfaces.
The display apparatus comprising a reflection plate having directivity, according to a second aspect of the present invention comprises: a liquid crystal display panel including liquid crystal between a pair of substrates; and a reflection plate having directivity and including a reflection film having a flat reflection surface, and an optical film having a first optical surface provided in the reflection surface and inclined in a first direction with respect to a normal line of the reflection surface thereby to reflect or refract light entering thereinto, second optical surfaces inclined in a second direction opposite to the first direction thereby to reflect or refract light entering thereinto, and a front surface into which external light enters and from which reflected light from the reflection surface and reflection
Casio Computer Co. Ltd.
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Mack Ricky
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