JPS6119196B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television image projection device that enlarges and projects a television image projected on a cathode ray tube onto a projection screen using an optical system.

In general, a television image projection device includes a cathode ray tube 1, a concave reflector 2 facing a face panel 1A, and a concave reflector 2, as shown in FIG.
The television image projected on the fluorescent surface 2 on the inner surface of the face panel 1A is formed by the concave reflecting mirror 2 and the correction lens 3. The image is enlarged and projected onto the projection screen 4 through the optical system.

If a curved surface with directivity is used as the projection screen 4, a bright projected image can be obtained.
By tilting the central axis 6 of the curved projection screen 4 by a predetermined angle α with respect to the optical axis 5 of the optical system, the reflected light 10 of the light 9 emitted from the indoor lighting lamp 8 can be directed downward. This allows only the effective light 7 to be directed toward the viewer.

However, in the television image projection device configured as described above, the television image A projected on the cathode ray tube 1 is placed at a position A' on the projection screen 4, and the television image B projected on the cathode ray tube 1 is placed at a position A' on the projection screen 4. are respectively formed at positions B' on the projection screen 4, and as a result, the enlargement ratio of the television image at B-B' becomes larger than the enlargement ratio of the television image at A→A'. Therefore, as shown in FIG. 2, the tube axis 11 (normal to the tangent line 12) of the cathode ray tube 1 is tilted by a predetermined angle β with respect to the optical axis 5 of the optical system, and the television images A and B are
It is necessary to equalize the magnification ratios of the optical systems. The angle β is expressed as α/m when the projection magnification is m, and when α = 20° and m = 20 times,
β=1°. And the total length of cathode ray tube 1 is
At 40cm, the rear end of the cathode ray tube 1 and the optical axis 5 of the optical system
The distance d from the CRT 1 is approximately 7 mm, and a portion of the effective television image is blocked at the rear of the CRT 1.
This will reduce the brightness characteristics of the device.

The present invention has been made to eliminate the above-mentioned drawbacks of the conventional art, and will be described below with reference to embodiments shown in the drawings.

As shown in FIG. 3, the tube axis 1 of the cathode ray tube 13
A face panel 13 forming the fluorescent surface of the cathode ray tube 13 is arranged coaxially with the optical axis 5 of the optical system consisting of the concave reflecting mirror 2 and the correction lens 3.
The central axis (normal line) 14 of A is inclined with respect to the tube axis 15 by a predetermined angle β (=α/m).

For this reason, the cathode ray tube 1 is
It is possible to prevent the above-mentioned disadvantage caused by the inclination of the tube axis 15 of No. 3, that is, the reduction in brightness of the television image due to a portion of the effective television image being blocked at the rear of the cathode ray tube. Further, since the optical system optical axis 5 and the tube axis 15 of the cathode ray tube 13 are made coaxial, the adjustment accuracy of the optical system can be improved, and the projection screen 2
The resolution of the television image on the screen can always be maintained at a good level.

As described above, according to the present invention, the optical axis of an optical system including a concave mirror facing a face panel forming a fluorescent surface of a cathode ray tube and a correction lens facing this concave mirror via the face panel is set to In addition to making the shaft coaxial,
The central axis of the face panel is tilted with respect to the tube axis, and by using a curved projection screen and setting the predetermined angles α and β in the conventional manner, the cathode ray tube can be It is possible to prevent a decrease in brightness due to the tube axis being tilted with respect to the optical axis of the optical system, and moreover, it is possible to improve the adjustment accuracy of the optical system and always obtain good resolution.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional television image projection apparatus, FIG. 2 is an enlarged view of essential parts of the same apparatus, and FIG. 3 is a block diagram showing an embodiment of the television image projection apparatus of the present invention. 13... Braun tube, 13A... Face panel, 14... Normal line, 15... Tube axis.

Claims (1)

[Claims] 1 If the optical axis of an optical system consisting of a concave reflecting mirror facing the face panel forming the fluorescent surface of the cathode ray tube and a correction lens facing this concave reflecting mirror via the face panel is coaxial with the tube axis of the cathode ray tube, A television image projection device characterized in that the central axis of the face panel is tilted with respect to the tube axis.