Optics: image projectors – Lens support – Lens position adjustable
Reexamination Certificate
2000-02-22
2001-09-04
Dowling, William (Department: 2851)
Optics: image projectors
Lens support
Lens position adjustable
Reexamination Certificate
active
06283599
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a projector with adjustable brightness and uniformity.
2. Description of the Related Art
The portable digital projectors commercially available in the market include DLP (Digital Light Processing) projectors and LCD panel (Liquid Crystal Display panel) projectors. The two kinds of projectors have a common defect: either the picture brightness or the uniformity of brightness produced by the projectors is poor.
FIGS. 1A and 1B
depict this conundrum. In
FIG. 1A
, the brightness on the central portion of a projection surface (xy-plane)
100
is strong but the brightness on the side portions of the projection surface
100
is weak. That is, the brightness is good but the uniformity of brightness is poor. In
FIG. 1B
, the uniformity of brightness on the projection surface
100
is greatly improved. However, the brightness on the central portion of the projection surface
100
is weakened.
Generally, a portable digital projector is connected to a computer for a user to make a briefing, or is connected to an image output device such as a video tape recorder, a VCD player, an LD player or a DVD player to show films. In the case of a briefing, the user prefers the brightness rather than the uniformity of brightness because the briefing room generally is not dark enough. In the case of showing films, however, the user prefers the uniformity of brightness rather than the brightness so as to produce clear and beautiful pictures. Taking both cases into consideration, the projector manufacturers generally compromise between the brightness and the uniformity in design. As a result, the projection picture produced by the projector is not bright enough when the user makes a briefing, and the uniformity of brightness is not good enough when the user watches a film.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a projection display device that solves the above-mentioned problem.
The projection display device of the present invention includes a lens module, a light source and an adjusting device. The lens module has a first lens and a second lens. The light source emits light through the first lens and the second lens to a projection surface. The adjusting device is used to change the distance between the first lens and the second lens, thereby adjusting the brightness and the uniformity of brightness on the projection surface to meet the needs of users in various applications.
In conclusion, the projection display device of the present invention allows the user to adjust the brightness and the uniformity of brightness so as to produce good projection quality in different situations.
REFERENCES:
patent: 4988188 (1991-01-01), Ohta
patent: 5029992 (1991-07-01), Richardson
patent: 5046838 (1991-09-01), Iwasaki
patent: 5467146 (1995-11-01), Huang et al.
patent: 5649753 (1997-07-01), Masumoto
patent: 5860721 (1999-01-01), Bowron et al.
patent: 5868483 (1999-02-01), Okada et al.
patent: 6054832 (2000-04-01), Kunzman et al.
Acer Peripherals Inc.
Dowling William
Nath & Associates PLLC
Novick Harold L.
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