JPH0795603A - Projection type color television device - Google Patents

Abstract

PURPOSE:To provide a projection type color TV device which can improve the luminance of images without requiring the luminance adjustment of a blue bell by using the same specifications of an electronic gun among the red, green end blue balls. CONSTITUTION:A projection type color TV device is provided with a red ball 1, a green bell 2, a blue ball 3, a screen 7 where the images formed on the fluorescent surfaces 1P, 2P end 3P of bells 1, 2 and 3, respectively are projected, end the projection lenses 4L, 5L and 6L which are placed near the surfeces 1P-3P and project the images on the screen 7. In such 8 constitution, the distance between a main lens 3M end the surface 3P of the ball 3 is set larger than those distances of other balls 1 and 2. Therefore, the beam spot of the ball 3 is larger then those of balls 1 and 2 and the luminance of the bell 3 is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type color television apparatus, and more particularly, the specifications of an electron gun for a projection type cathode ray tube for forming a blue image are the same as those of a projection type cathode ray tube for forming an image of another color. The present invention relates to a projection type color television device capable of forming a projected image of high brightness by improving its brightness.

[0002]

2. Description of the Related Art The brightness quality of an image of a projection type color television apparatus of this type depends on its blue brightness.

A projection type cathode ray tube used in a conventional projection type color television apparatus has a specification of a projection type cathode ray tube for forming a blue image (hereinafter referred to as a blue ball) which is the same as that of a projection type cathode ray tube for forming a red image ( (Hereinafter referred to as a red sphere) and a projection type cathode ray tube for forming a green image (hereinafter referred to as a green sphere) are made different to increase the spot diameter of the electron beam, or a red sphere, a green sphere and a blue sphere. Each sphere has the same specifications, and the blue sphere is defocused to increase the diameter of the blue electron beam spot to increase the brightness.

For example, Japanese Patent Laid-Open No. 60-200216 can be cited as a disclosure of the prior art relating to this type of projection color television apparatus.

[0005]

In the former technique in the above-mentioned prior art, that is, in which the specification of an electron gun for a blue ball is different from the specification of an electron gun for a red ball and a green ball, a projection type cathode ray tube having different electron gun specifications is used. There is a problem that it is necessary to prepare a separate one, and a separate drive circuit is designed, which complicates manufacturing and assembly and adjustment.

The latter technique, that is, a red sphere, a green sphere,
If the blue ball has the same electron gun specifications and defocuses the electron beam of the blue ball to increase the brightness, there is a problem that the focus adjustment becomes troublesome and the adjustment work becomes complicated.

The object of the present invention is to solve the above-mentioned problems of the prior art, and to adjust the brightness of the blue sphere by using the same electron gun specifications as the red sphere, the green sphere, and the blue sphere. It is to provide a projection-type color television device that improves without doing so.

[0008]

In order to achieve the above object, the present invention provides a projection type cathode ray tube for forming a red image, a green image and a blue image, and fluorescent light of each of the projection type cathode ray tubes. Projection type color television apparatus having at least a screen for projecting an image formed on a surface thereof, and a projection lens arranged in proximity to the fluorescent screen of each of the projection type cathode ray tubes to project the image on the screen. In the above, the distance between the main lens of the projection type cathode ray tube for forming the blue image and the fluorescent screen is longer than that of the projection type cathode ray tube for forming the red image and the green image. To do.

[0009]

In general, the electron beam diameter in the cathode ray tube changes depending on the distance between the main lens and the fluorescent screen.

FIG. 4 is an explanatory view of the relationship between the distance between the main lens and the fluorescent screen and the electron beam diameter on the fluorescent screen. The horizontal axis represents the distance between the main lens and the fluorescent screen, and the vertical axis represents the electron. Indicates the beam spot diameter.

As shown in the figure, the electron beam spot diameter increases as the distance between the main lens and the phosphor screen increases.

The brightness of the blue sphere increases as the spot diameter of the electron beam increases.

FIG. 5 is an explanatory diagram of the relationship between the spot diameter of the electron beam and the brightness of the blue sphere, where the horizontal axis represents the electron beam spot diameter and the vertical axis represents the brightness of the blue sphere.

As shown in the figure, it can be seen that the brightness of the blue sphere increases as the spot diameter of the electron beam increases.

FIG. 6 is an explanatory view of the relationship between the cathode current and the electron beam spot diameter due to the difference in the distance between the main lens and the phosphor screen. The horizontal axis represents the cathode current and the vertical axis represents the electron beam spot. The diameter is shown as a, a is the change curve of the electron beam spot diameter when the distance between the main lens and the fluorescent screen is increased, and b is the normal length of the distance between the main lens and the fluorescent screen. It is a change curve of the electron beam spot diameter. The specifications of the electron gun are the same.

As shown in the figure, if the specifications of the electron gun are the same and the distance between the main lens and the phosphor screen is long, the electron gun on the phosphor screen in all the cathode current regions is shorter than the short one. The electron beam spot diameter becomes larger.

FIG. 7 is an explanatory view of the relationship between the brightness of a blue sphere and the cathode current. The cathode current is plotted on the horizontal axis and the brightness of the blue sphere is plotted on the vertical axis, and a is the main lens and the phosphor screen. The curve of the brightness of the blue sphere when the distance between them is increased, and b is the curve of the brightness of the blue sphere with the distance between the main lens and the fluorescent surface being the normal length. The specifications of the electron gun are the same.

As can be seen from this relationship diagram, when the distance between the main lens and the fluorescent screen is increased, the brightness is higher than when it is decreased.

Based on the above facts, the projection type color in which the brightness of the blue sphere is improved by using the same electron gun specifications for all the red sphere, green sphere and blue sphere by adopting the constitution of the present invention. A television device can be provided.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic view for explaining the constitution of one embodiment of a projection type color television apparatus according to the present invention,
1 is a red sphere, 2 is a green sphere, 3 is a blue sphere, 1 _M is a main lens composed of a red sphere electron gun, 2 _M is a main lens composed of a green sphere electron gun, 3 _M is a blue sphere The main lens composed of the electron gun,
1 _P is a fluorescent surface of a red sphere, 2 _P is a fluorescent surface of a green sphere, 3 _P is a fluorescent surface of a blue sphere, 4 _L is a projection lens provided on a red sphere, 5 _L is a projection lens provided on a green sphere, 6 _L is the projection lens on the blue ball,
7 is a projection screen.

In the figure, the red sphere 1, the green sphere 2, and the blue sphere 3 have the same electron gun specifications, and the distance L _R between the main lens 1 _M of the red sphere 1 and the fluorescent screen 1 _P and the green sphere are the same. The distance L _G between the second main lens 2 _M and the fluorescent screen 2 _P is the same, and the main lens 3 _M of the blue ball 3
And the fluorescent screen 3 _P are the distances L _R and L between the two spheres.
Longer than _G. Here, L _G −L _R (L _G ) = 10 mm
And

On the central axis of the green sphere 2, a projection screen 7 is arranged at a position facing the fluorescent screen 2 _P and spaced apart at a constant interval. A red sphere 1 and a blue sphere 3 are installed at a predetermined angle.

The images formed on the fluorescent screens 1 _P , 2 _P and 3 _P of the red sphere 1, the green sphere 2 and the blue sphere 3 arranged as described above are projected onto the entire surface of each sphere by the projection lens 4 respectively. _L , 5 _L ,
6 _L is superimposed on the projection screen 7 to form a color image.

With this configuration, a large screen image is obtained on the projection screen 7, the brightness of the blue component of the image formed by projection is increased, and the image quality is improved.

FIG. 2 is a front view of a rear projection type television device as an example of the projection type color television device, in which three projections of a red sphere, a green sphere and a blue sphere are projected on the lower portion 20 of the projection screen 7. The cathode ray tube, the projection optical system, the receiver circuit, etc. are housed.

FIG. 3 is a side sectional view for explaining the schematic internal structure of the projection type color television apparatus shown in FIG.
Reference numeral 21 is a mirror, 22 is a lens coupler, and the same parts as those in FIG.

In the figure, a projection type cathode ray tube (red ball 1,
A projection lens (4 _L , 5 _L , 6 _L ,) is coupled to the green sphere 2 and the blue sphere 3) via a lens coupler 22, and is directed toward a mirror 21 installed at a predetermined angle above the rear surface of the device. Will be placed.

The three-color image formed on the fluorescent surface of the projection type cathode ray tube (red ball 1, green ball 2, blue ball 3) is reflected by the projection lens (4 _L , 5 _L , 6 _L ,) on the mirror 21. It is projected on the projection screen 7 via the screen.

The projection type color television apparatus incorporating the projection type cathode ray tube utilizing such rear projection can reduce the depth of the television apparatus and is advantageous in compactness.

In the projection type color television apparatus described above, the projection type cathode ray tube (red ball 1,
By using the green sphere 2 and the blue sphere 3), it is possible to obtain a high quality projection type color television device with improved brightness.

Needless to say, the present invention is not limited to such a rear projection type television device, but can be applied to a projection type color television device of a type in which a projection screen is separated.

[0033]

As described above, according to the present invention,
It is possible to provide a projection type color television device capable of reproducing a bright image by using the same electron gun specifications for all the red, green and blue balls.

That is, the same electron gun specifications are used for all the red, green, and blue spheres, so that focus adjustment for defocusing the electron beam of the blue sphere to raise the brightness is not necessary, and the brightness of the blue sphere can be adjusted. It is possible to provide a projection type color television device capable of improving the brightness without needing.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a configuration of an embodiment of a projection type color television device according to the present invention.

FIG. 2 is a front view of a rear projection type television device as an example of a projection type color television device.

FIG. 3 is a side sectional view for explaining a schematic internal structure of the projection type color television device shown in FIG.

FIG. 4 is an explanatory diagram of a relationship between a distance between a main lens and a fluorescent screen and an electron beam spot diameter on the fluorescent screen.

FIG. 5 is an explanatory diagram of the relationship between the spot diameter of an electron beam and the brightness of a blue ball.

FIG. 6 is an explanatory diagram of the relationship between the cathode current and the electron beam spot diameter due to the difference in the distance between the main lens and the phosphor screen.

FIG. 7 is an explanatory diagram of the relationship between the brightness of a blue sphere and the cathode current.

[Explanation of symbols]

1 Red sphere 2 Green sphere 3 Blue sphere 1 _M Main lens composed of red electron gun 2 _M Main lens composed of 2 _M green ball electron gun 3 _M Main lens composed of blue ball electron gun 1 _P Fluorescent surface of red sphere 2 _P Fluorescent surface of green sphere 3 _P Fluorescent surface of blue sphere 4 _L Projection lens provided on red sphere 5 _L Projection lens provided on green sphere 6 _L Projection lens provided on blue sphere 7 Projection screen.

Claims (1)

[Claims] 1. A projection type cathode ray tube for forming a red image, a green image and a blue image, and a screen for projecting an image formed on a fluorescent screen of each of the projection type cathode ray tubes.
In a projection type color television device having at least a projection lens arranged in close proximity to the phosphor screen of each of the projection type cathode ray tubes to project the image on the screen, the projection type cathode ray tube for forming the blue image. The projection type color television device is characterized in that the distance between the main lens and the fluorescent screen is longer than that of the projection type cathode ray tube for forming the red image and the green image.