Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
1999-08-23
2001-05-29
Allen, Stephone B. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C353S079000, C359S649000
Reexamination Certificate
active
06239424
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a light detecting system, and more particularly, to a light detecting system for detecting light projected from a projector.
2. Description of the Prior Art
Please refer to FIG.
1
and
FIG. 2
FIG. 1
is a perspective view of a prior art light detecting system
50
and a projector
52
.
FIG. 2
is a front view of the light detecting system
50
in FIG.
1
. The light detecting system
50
is used for detecting light projected from the projector
52
. When the projector
52
is initiated, it will project a picture image forward. The light detecting system
50
comprises a frame
54
positioned at a predetermined position in front of the projector
52
, thirteen light sensors
56
fixed on the frame
54
for detecting the picture image, a control device
60
connected with the projector
52
, and a screen
58
installed on the frame
54
to form a surface with a position mark. The control device
60
is used to output an image signal to the projector
52
so that the projector
52
can project a picture image onto the screen
58
. The position mark on the screen
58
is used to calibrate the position of the picture image on the screen
58
.
The screen
58
has five equally spaced vertical lines
53
A,
53
B,
53
C,
53
D,
53
E and five equally spaced horizontal lines
55
A,
55
B,
55
C,
55
D,
55
E. The vertical and horizontal lines form a number of intersections on the screen
58
. Thirteen of these intersections are defined as sampling positions. The thirteen light sensors
56
are installed at corresponding sampling positions for detecting light emitted from the projector
52
so as to calculate various parameters of the picture image such as average luminous flux, light uniformity, color temperature, color coordinate, color balance, color uniformity and color contrast ratio.
Because the light sensors
56
are very expensive and the light detecting system
50
uses thirteen of them, the cost of the light detecting system
50
becomes extremely high. Moreover, the light sensors
56
are fixed on the screen
58
, therefore the number of sampling positions cannot be increased when more detailed analysis of the picture image is required.
SUMMARY OF THE INVENTION
It is therefore a primary objective of the present invention to provide a light detecting system to solve the above mentioned problems.
Briefly, in a preferred embodiment, the present invention provides a light detecting system for detecting light projected from a projector. When the projector is initiated, it will project a picture image forward. The light detecting system comprises:
a frame positioned at a predetermined position in front of the projector;
a detecting device movably installed on the frame for detecting the picture image;
a driving device installed on the frame for moving the detecting device; and
a control device connected with the driving device and the detecting device for controlling the driving device to move the detecting device to various sampling positions on the frame and to control the detecting device to detect the picture image at each of the sampling positions.
It is an advantage of the present invention that the light detecting system utilizes the moveable light detecting device to detect the picture image so that the cost of the light detecting system is greatly reduced and more samples of the picture image can be taken when required.
These and other objects and the advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
REFERENCES:
patent: 4343539 (1982-08-01), Task
patent: 5850085 (1998-12-01), Rosenbluth
patent: 5907437 (1999-05-01), Sprotbery et al.
Allen Stephone B.
Hsu Winston
Primax Electronics Ltd.
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