Optics: image projectors – Composite projected image – Multicolor picture
Reexamination Certificate
1999-09-10
2001-11-20
Dowling, William (Department: 2851)
Optics: image projectors
Composite projected image
Multicolor picture
C353S098000, C353S094000, C349S061000
Reexamination Certificate
active
06318863
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 88100890, filed Jan. 21, 1999, the full disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates in general to an illumination device. More particularly, this invention relates to an illumination device of a display.
2. Description of the Related Art
The conventional projection apparatus is basically applied to a front projection type or a large screen back projection type display. Light sources such as halogen lamps and arc lamps with enough luminance, for example, high pressure mercury lamp, metal halogen lamp, and xenon lamps, have to be used. These kinds of lamps have the advantage of high luminance, but also have the disadvantages such as high power consumption, short lifetime and high temperature. Therefore, these kinds of lamps are only used while a high luminance is required.
Referring to both FIG.
1
A and
FIG. 1B
, two conventional illumination devices are shown schematically.
FIG. 1A
shows a projection apparatus disclosed in U.S. Pat. No. 5,418,583. A first lens array
20
and a second lens array integrator
30
are used to achieve the uniformity of a light source
10
, followed by projecting the light onto a light valve
40
.
FIG. 1B
shows another projection apparatus disclosed in U.S. Pat. Nos. 4,656,562 and 5,634,704. A light pipe integrator
25
and a lens
35
are used to uniformize a light source
10
and to project the uniform light onto a light valve
40
. In Both
FIGS. 1A and 1B
, halogen lamps or various kinds of arc lamps have to be used to obtain the required luminance. Therefore, both of these two conventional projection apparatus have disadvantages such as high power consumption, short lifetime, abundant ultra-violet irradiation and high temperature. These conventional projection apparatus are thus not suitable for use in a display with a small feature size.
A desktop display normally has a diagonal length less than about 30 inches. Thus, the high luminance required by those large screens or display is not demanded for a desktop display. In addition, the desktop display is very often in an on status, so that a light source has to continuously provide a light for illumination. Again, those conventional illumination devices which use high pressure mercury lamp do not have enough lifetime are not suitable for use as a desktop display.
Apart from the high power consumption, short lifetime, and high temperature, the light source with a high luminance further has the disadvantages of hazard in application and high fabrication cost.
SUMMARY OF THE INVENTION
The invention provides an illumination device. Multiple light emitting devices are used as a light source. The light emitting devices have advantages such as low power consumption, long lifetime, and generating low thermal energy. Since lights emitted from the multiple light emitting devices overlay on a light valve, the lifetime of the illumination device is increased by an order of the number of the light emitting devices. The uniformity of the light displayed on the light valve is also enhanced. Since the light source with high luminance is not used, so that the drawbacks in the conventional illumination devices are resolved. In addition, since less thermal energy is generated, materials such as plastic can be used for optical lens to reduce the fabrication cost.
In one aspect, the invention further provides a projection apparatus using the above mentioned illumination devices. The light emitting from the illumination devices travels through the projection apparatus and projects onto a screen. The projection apparatus using the illumination devices have the advantages of low cost and high efficiency.
In one embodiment of the invention, an illumination device including a light source and a uniform illuminating means are provided. The illumination device has multiple light emitting devices, while lights emitted from the light emitting devices are uniformized by the uniform illuminating means to project onto a light valve, for example, a LCD for display.
Since most of the light valve can accept polarized light, therefore, the polarization converter is frequently used to efficiently utilize the light provided by the illumination device.
Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
REFERENCES:
patent: 4735495 (1988-04-01), Henkes
patent: 5347433 (1994-09-01), Sedlmayer
patent: 5398086 (1995-03-01), Nakano et al.
patent: 5765934 (1998-06-01), Okamori et al.
patent: 5808800 (1998-09-01), Handschy et al.
patent: 5829858 (1998-11-01), Levis et al.
patent: 5971545 (1999-10-01), Haitz
Chan Sheng-Hsiung
Chuang Fu-Ming
Shiau Tzeng-Ke
Tiao Kuo-Tung
Yoo Jinn-Chou
Dowling William
Huang Jiawei
Industrial Technology Research Institute
J. C. Patents
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