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Projection display apparatus
| Details |
Inventors: Miyatake, Yoshito; Masumoto, Yoshihiro;
Assignee: Matsushita Electric Industrial Co., Ltd. (Osaka, JP)
Primary Examiner: Haroian; Harry N.
Assistant Examiner:
Attorney, Agent or Firm: Wenderoth, Lind & Ponack
A projection display apparatus has a light source, a component color separator, a light transmitter(s), three light valves, a light combiner, a single projection lens, and a drive circuit. The light transmitter includes an input side convergent lens for producing a real image of a luminous element in the light source at a location adjacent to a central convergent lens. The central convergent lens produces a real image of an object situated about a position of the input side convergent lens at a location adjacent to an output side convergent lens. The output side convergent lens permits its output light to reach the projection lens. Accordingly, divergent light is converged along a considerably extending portion of the optical path and directed to the projection lens so that the efficiency of light in use can be improved, thus allowing the projection display apparatus to remain compact in size and provide a great light output power. |
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DETAILED DESCRIPTION The present invention is directed in view of the above respects towards a projection display apparatus adapted to improve efficiency in the use of light in an optical system and yet, to remain compact in size and provide a great light output power.
To achieve the above object, a projection display apparatus according to the present invention comprises a light source for generating a light containing three primary colors, component color separator means for separating the output light from the light source into three primary color lights, three light valves having formed therein optical images for modulating the three primary color lights separated by the component color separator means respectively, a drive circuit for driving the three light valves in response to a video signal to form the optical images, light combiner means for combining the modulated lights from the three light valves into a composite light, a projection lens for projecting the composite light onto a screen to obtain an enlargement of the optical images, and light transmission means disposed across an optical path having a distance from the component color separator means to a corresponding light valve larger than two times an width of an effective flux of light entering the light valve for guiding a light output from the component color separator means to the corresponding light valve.
The light transmission means comprises an input side convergent lens disposed at an input end, an output side convergent lens disposed at an output end, and a central convergent lens disposed across an optical path between the input side and output side convergent lenses.
The input side convergent lens produces a real image of a luminous element in the light source at a location adjacent to the central convergent lens.
The central convergent lens produces a real image of an object adjacent to the input side convergent lens at a location adjacent to the output side convergent lens.
The output side convergent lens is arranged to direct its light output to the projection lens
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LCD 
