Color image display device and projection-type image display...

Optics: image projectors – Composite projected image – Multicolor picture

Reexamination Certificate

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Details

C353S034000, C353S037000, C359S201100, C359S204200, C359S212100, C359S216100, C359S223100

Reexamination Certificate

active

06568811

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a color image display device and a projection-type image display apparatus that display a color image with one light valve as a light modulating member.
2. Description of Related Art
Along with a sufficient supply of video equipment and video software such as a video tape recorder and a video disk player, the demand for a large screen image display apparatus for enjoying powerful images has become intensified in recent years. As a conventional large screen image display apparatus, there is an image display apparatus that uses a liquid crystal panel (a light valve) for an image display portion so as to modulate light emitted from a light source spatially by the liquid crystal panel and project an image onto a screen. Currently commercialized image display apparatus using the liquid crystal panel can be classified roughly into a three-plate system using three liquid crystal panels and a single-plate system using one liquid crystal panel.
FIG. 21
shows a configuration of one example of the conventional three-plate system image display apparatus.
Light emitted from a lamp
901
as a light source and light reflected by a reflection mirror
902
are converged by a focusing lens
903
, and then separated into red, green and blue components of primary colors by a blue-reflecting dichroic mirror
904
and a green-reflecting dichroic mirror
905
. Light beams of these primary colors respectively are directed to a liquid crystal panel for red light
912
, a liquid crystal panel for green light
913
and a liquid crystal panel for blue light
914
, combined by a color combination prism
915
, and then projected onto a screen
917
by a projection lens
916
. In this figure, total reflection mirrors
906
,
907
and
908
change optical paths of the light beams, and lenses
909
,
910
and
911
adjust the incident angles of the light beams entering the respective liquid crystal panels. A white light source used for the lamp
901
as the light source is, for example, a discharge-type extra-high pressure mercury vapor lamp or metal halide lamp, or a thermoluminescence-type halogen lamp.
The liquid crystal panel for red light
912
, the liquid crystal panel for green light
913
and the liquid crystal panel for blue light
914
are driven by a video signal for red light, a video signal for green light and a video signal for blue light respectively. The light irradiated by the lamp
901
is modulated spatially when passing through the respective liquid crystal panels, and projected onto the screen
917
by the projection lens
916
as an image.
FIG. 22
shows a configuration of one example of the conventional single-plate system image display apparatus.
Light emitted from a lamp
931
as a light source and light reflected by a reflection mirror
932
are converged by a focusing lens
933
, and then irradiated on a liquid crystal panel
940
. The liquid crystal panel
940
is constituted by a mosaic color filter substrate
941
and a TFT array substrate
942
as shown in FIG.
23
. When a white light beam from the lamp
931
passes through the color filter
941
, red, green and blue light beams of primary colors are obtained. These light beams of primary colors that have passed through the liquid crystal panel
940
are projected onto a screen
935
by a projection lens
934
.
In the conventional three-plate system image display apparatus described above (see FIG.
21
), the liquid crystal panel is driven by the video signal so that the liquid crystal panel changes transmittance of the light, thereby modulating the light spatially so as to display the image. Since the entire spectrum of the white light from the lamp can be utilized, the image display apparatus of this system has a high efficiency of light utilization. However, the necessity of the three liquid crystal panels, a color separation optical system, a color combination optical system and a convergence adjusting mechanism between the liquid crystal panels has posed a problem in that this system is relatively expensive.
On the other hand, the conventional single-plate system image display apparatus described above (see
FIGS. 22 and 23
) is compact and inexpensive because the image formed on the liquid crystal panel having the mosaic color filter simply is magnified and projected onto the screen. However, since this system obtains desired light of the primary colors by absorbing light with an unwanted color using the color filter, the efficiency of light utilization is low (one-third or less), making it very difficult to increase brightness.
SUMMARY OF THE INVENTION
In an image display apparatus using a single image display panel, it is a first object of the present invention to provide a color image display device and a projection-type image display apparatus that can utilize light from a light source effectively and display a high-brightness image. Also, it is a second object of the present invention to provide a small color image display device and a small projection-type image display apparatus using a single image display panel. Furthermore, in the apparatus achieving the above objects, it is a third object of the present invention to provide a color image display device and a projection-type image display apparatus that are provided with a preferable adjusting means.
In order to achieve the above-mentioned objects, the present invention has the following configurations.
A color image display device according to a first configuration of the present invention includes a light source portion for emitting respective light beams of red, green and blue, an image display panel provided with many pixels for modulating an incident light according to color signals of at least red, green and blue, an optical system for directing the respective light beams to enter the image display panel so that the respective light beams from the light source portion form belt-like illuminated regions at different positions on the image display panel and the regions illuminated by the respective light beams move continuously on the image display panel, and an image display panel driving circuit for driving each of the pixels of the image display panel. Each of the pixels is driven by a signal corresponding to a color of light entering this pixel, thereby displaying a color image. The respective light beams are directed to enter the image display panel so that the illuminated regions adjacent to each other on the image display panel partially overlap each other. The pixel that the light beams of the overlapping two colors enter is driven by a brightness signal component.
With this first configuration, the color image can be displayed using only one image display panel having neither a color filter nor a pixel exclusively for the respective light beams. Moreover, since the red, green and blue light beams are irradiated simultaneously on different regions on the image display panel so as to display red, green and blue images on these regions simultaneously, it is possible to utilize light effectively and display a high-brightness image.
Also, unlike the case of the conventional color image display apparatus using the single image display panel (see FIG.
22
), the image display panel does not have the pixels exclusively for displaying the red, green and blue images. Therefore, ⅓ of the number of the pixels of the conventional image display panel (see
FIG. 23
) is sufficient for the image display panel of the present invention, allowing a cost reduction.
Furthermore, by partially overlapping the illuminated regions of the adjacent two colors on the image display panel, a focused area of the light beams can be made larger than that in the case without any overlapping portion, achieving a smaller focusing optical system, and making it possible to reduce the size of the entire device. Moreover, a point light source does not have to be used. In addition, by using the light of the overlapping portions for the display of a brightness component, the light from the light

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