Optical system in projection television receiver

Details Optical system in projection television receiver Optical system in projection television receiver

2000-07-24

2002-12-31

Miller, John (Department: 2614)

Television

Video display

Projection device

C348S776000, C348S779000, C348S781000

Reexamination Certificate

active

06501517

ABSTRACT:

PRIORITY
This application claims priority to an application entitled “Optical System in Projection Television Receiver” filed in the Korean Industrial Property Office on Jul. 24, 1999 and assigned Serial No. 99-30247, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an optical system in a projection television receiver and, more particularly, to an optical system in a projection television receiver in which R, G and B cathode ray tubes are arranged in a delta type array with a view to facilitating control of convergence.
2. Description of the Related Art
Unlike general televisions, the projection television receiver has three cathode ray tubes (CRTs) for red (R), green (G) and blue (B) colors and enlarges an image formed on the R, G and B CRTs through an optical system comprised of a plurality of reflecting mirrors and lenses, thereby displaying the enlarged image on a large-sized screen.
FIGS. 1 and 2
are diagrams illustrating the operational principle of an optical system in the related art projection television receiver and an array of R, G and B CRTs. Images each projected from R, G and B CRTs
100
,
102
and
104
are enlarged at lens parts
106
,
108
and
110
, reflected by a reflecting mirror
112
and displayed on a screen
114
. In the related art projection television receiver, as shown in
FIG. 2
, the R, G and B CRTs
100
,
102
and
104
are arranged in a straight line with respect to the screen
114
, i.e., the G CRT
102
is at the center of the screen
114
, with the R and B CRTs
100
and
104
being positioned on the left and right sides, respectively, thereof. As the image projected on the screen
114
from the R or B CRT
100
or
104
has an excessively large angle of projection with respect to the image from the G CRT
102
, as shown in
FIG. 3
, the images are out of accord with one another on the screen and thus the images are distorted. Such distortion of the image intensifies at the edges of the screen
114
.
FIG. 4
shows distorted R, G and B images displayed on the screen due to straight arrangement of the CRTs. It is shown in
FIG. 4
that distortion of the R, G and B images
400
,
402
and
404
appear more significant on the left and right sides of the screen
114
.
The related art projection television receiver, to overcome such a distortion problem, controls the convergence to make the images projected from the respective CRTs converged on a screen. However, compensation for the distortion of an image on the screen that results from the convergence control has a limitation and an excessive convergence control may incur an overload due to saturation of a power level.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an optical system in a projection television receiver for facilitating control of convergence.
To achieve the above object, there is provided an optical system in a projection television receiver including: a screen for simultaneously displaying R (Red), G (Green) and B (Blue) images thereon; and a light source part comprising R, G and B cathode ray tubes. The R and B cathode ray tubes project the R and B images on the screen via a reflecting mirror, with the G cathode ray tube being set together with the R and B cathode ray tubes in a delta type array and projecting the G image directly on the screen.


REFERENCES:
patent: 3969648 (1976-07-01), Hergenrother et al.
patent: 4870321 (1989-09-01), Kamohara
patent: 4883438 (1989-11-01), Hernqvist
patent: 5091673 (1992-02-01), Shimoma et al.
patent: 5382883 (1995-01-01), Chen et al.
patent: 5663774 (1997-09-01), Baik
patent: 5726719 (1998-03-01), Tanaka et al.

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