Liquid crystal cells – elements and systems – Particular structure – Particular illumination
Reexamination Certificate
2000-05-01
2004-08-03
Nguyen, Dung (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Particular illumination
C349S064000, C349S065000
Reexamination Certificate
active
06771331
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a lighting device in which ambient light collected and captured in a light-collecting unit is converted into a transmitting light and guided to an object to be illuminated. The present invention also relates to a liquid crystal display device provided with the lighting device.
(2) Description of the Prior Art
Liquid crystal display panels are widely utilized for an information display unit in camcorders, digital cameras, and the like. For such liquid crystal display devices, generally, transmissive-type liquid crystal display panels have been employed. In a display panel for such appliances as camcorders and digital cameras, it is necessary to prevent a display defect caused by ambient light incident on the panels, since such appliances are often used under strong ambient light. Accordingly, it is essential that liquid crystal display panels used for such appliances have a high luminance. In view of this, Japanese Unexamined Patent Publication No. 10-123507 discloses an apparatus having the following configuration. In the apparatus, a light-collecting unit for collecting ambient light is provided on an upper face of the apparatus, and the ambient light collected in the light-collecting unit is guided to a back surface of a liquid crystal display panel using microprisms so as to illuminate the liquid crystal display panel from the back surface of the panel, for the purpose of increasing a brightness of the liquid crystal display panel.
However, in the above-described device of prior art, the light-collecting unit is placed at the back of the liquid crystal display panel and formed in a rectangular-like shape on the upper face of the apparatus, and ambient light is directly guided to the back surface of the liquid crystal display panel. Therefore, the light-collecting unit cannot be made large, restricted to a relatively small area of a rectangular-like shape. It is noted here that the size of an area of the light-collecting unit directly influences a brightness of the display panel. Accordingly, the prior art device has at least a drawback that the improvement in brightness is insufficient since the light-collecting unit cannot be made large.
SUMMARY OF THE INVENTION
In view of the foregoing and other drawbacks in prior art, it is an object of the present invention to provide a lighting device and a liquid crystal display device in which, unlike conventional light-collecting units, two separate units each having a different function (i.e., a light-collecting unit for collecting and capturing ambient light, and a light-guiding unit, connected to the light-collecting unit, for guiding the light to a liquid crystal display panel) are provided to increase an occupied area of the light-collecting unit and thereby to achieve an increased brightness.
These and other objects are accomplished by providing a lighting device capable of utilizing ambient light for illuminating an object to be illuminated, comprising:
a light-collecting unit for collecting ambient light, and
means for converting at least a part of the ambient light into a transmitting light transmitted in the light-collecting unit, the means for converting being provided in the light-collecting unit.
By employing such a configuration, ambient light is captured and converted into a transmitting light in the light-collecting unit, and thereby ambient light is efficiently guided to the object to be illuminated.
The above-described lighting device according to the invention may further comprise a plurality of means for redirecting a proceeding direction of light, provided in a light path between the light-collecting unit and the object to be illuminated, and may be such a device in which a proceeding direction of the ambient light emitted from the light-collecting unit is redirected a plurality of times by the means for redirecting, so that the ambient light is guided to the object to be illuminated.
In the above-described configuration, the ambient light from the light-collecting unit is guided to the object to be illuminated by the means for redirecting, and thereby many variations in relative positions of the light-collecting unit and the object to be illuminated are made possible. The means for redirecting is not limited to a means that redirects a light by reflection, but other variations, for example, such means that redirects a light by refraction, diffraction, and the like may be employed.
The above-described lighting device may be such a device in which the light-collecting unit comprises a flat outward surface on which the ambient light is incident and a serrated reflecting surface provided on a surface opposite to the outward surface.
By employing the above configuration, ambient light can be efficiently converted into a transmitting light.
The above-described lighting device may be such a device in which the means for redirecting a proceeding direction of light is a reflecting surface for reflecting the ambient light.
The present invention also provides a liquid crystal display device capable of utilizing ambient light for illuminating a liquid crystal panel provided in a casing, comprising:
a light-collecting unit for collecting the ambient light and converting at least part of the ambient light into a transmitting light transmitted in the light-collecting unit, and
a light-guiding unit for guiding the transmitting light to the liquid crystal panel by redirecting a light path of the transmitting light.
By employing the above configuration, unlike conventional light-collecting units, two separate units each having a different function (i.e., a light-collecting unit for collecting and capturing ambient light, and a light-guiding unit, connected to the light-collecting unit, for guiding the light to a liquid crystal display panel) are provided in the device. Accordingly, an occupied area of the light-collecting unit is increased, and thereby an increased brightness is achieved.
A liquid crystal display device according to the invention may be such a device in which the light-collecting unit comprises a serrated reflecting surface provided on a surface of the light-collecting unit opposite to an outward surface of the light-collecting unit on which the ambient light is incident.
The serrated reflecting surface converts ambient light into a transmitting light to transmit the light to the light-guiding unit.
A liquid crystal display device according to the invention may be such a device in which the light-collecting unit is provided on an upper face of the casing of the liquid crystal display device.
By employing such a configuration, ambient light coming from an upward direction can be efficiently guided to the liquid crystal display panel.
A liquid crystal display device according to the invention may be such a device in which the light-collecting unit is provided on an upper face of the casing of the liquid crystal display device.
By employing such a configuration, ambient light coming from an upward direction and a sideward direction can be efficiently guided to the liquid crystal display panel.
A liquid crystal display device according to the invention may be such a device in which:
the light-collecting unit comprises a first light-collecting unit formed on a face of the casing opposite to a face on which the liquid crystal panel is provided, and a second light-collecting unit formed on an upper face of the casing, and
one of the end faces of the second light-collecting unit is connected to one of the end faces of the first light-collecting unit, and the other end face of the second light-collecting unit is connected to one of the end faces of the light-guiding unit.
By providing the first light-collecting unit and the second light-collecting unit as described above, more ambient light can be collected, and a brightness of the liquid crystal panel is further increased.
A liquid crystal display device according to the invention may further comprise:
a flat reflecting surface formed at a connecting part of the first light-collecti
Kubota Hirofumi
Nakao Kenji
Uemura Tsuyoshi
Matsushita Electric - Industrial Co., Ltd.
Nguyen Dung
Parkhurst & Wendel L.L.P.
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