JPH0636710A - Display control circuit and device - Google Patents

Abstract

PURPOSE:To optically improve the flatness of a display screen and reduce the glaring of the external light by forming the front face of an image display face into a concave lens structure. CONSTITUTION:The phosphor face 3 of a cathode-ray tube 1 is formed into a normal concave structure as seen from the tube inside, and the outer face 11 of the cathode-ray tube 1 is formed into a flat or concave structure. A glass tube pinched by the faces 3, 11 exerts a concave lens action, and the optical image forming face of the image formed on the face 3 is floated toward the view point by the refraction factor of glass when viewed from the outside of the tube. The radius of curvature of the optical image forming face is increased nearly to a flat surface. The image is made flat, and the glaring of the external light is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a cathode ray display tube used in televisions and the like.

[0002]

2. Description of the Related Art Conventionally, a cathode ray display tube (hereinafter, abbreviated as CRT) used in a television or the like has a convex display surface when viewed from the outside, based on its principle.

As shown in FIG. 2, this is an inevitable structure for scanning a cathode ray inside the CRT to cause the phosphor to emit light.

The smaller the curvature of the CRT display surface, that is, the larger the radius of curvature, the flatter the display surface becomes, and it is easier to see visually, and there are advantages such as less reflection of an electric light on the glass surface. Efforts for flattening are still being made.

[0005]

However, the larger the radius of curvature of the display surface is, the more the interior is in vacuum, so that the problem of the strength of the CRT glass tube, the problem of the deflection distortion of the electron beam, etc. become more serious. There is a limit to flattening the display surface.

In view of the above problems, it is an object of the present invention to enhance the flatness of the display surface without impairing the intensity of the CRT and the linearity of the deflection.

[0007]

In the present invention, CR is used.
By providing a concave lens on the entire surface of T and optically increasing the flatness of the display screen by the action of the concave lens, and making the outer surface of the lens flat or concave, the reflection of external light is reduced. .

[0008]

In this structure, the image produced by emitting light from the fluorescent substance by the electron beam exists on the inner surface of the CRT display surface, but by placing a concave lens on the entire surface of the CRT,
The image is optically formed in front of the fluorescent surface, and the movement of the optical image is increased toward the end of the lens. As a result, the curvature of the optical image formation surface is smaller than that of the electronic image formation surface. That is, it becomes flat.

In the past, there have been some cases in which a convex lens is placed on the entire surface of the CRT to make the screen look large, but this has different purposes, structures, and effects.

[0010]

First, an embodiment of the present invention will be described with reference to FIG.

In FIG. 1, 1 is a cathode ray display tube (hereinafter C
RT abbreviated glass outer tube, 2 shadow mask, 3 fluorescent body, 4 electron gun, 5 cathode ray (electron beam), 6 deflection coil, 11 yes CRT outer surface, emitted from electron gun 4. The cathod rays 5 (three electron beams in the case of color) are deflected and scanned by the deflection coil 6, and in the case of a color TV, they pass through the shadow mask and reach the phosphors 3 of the three primary colors to project an image on the surface of the phosphor. .

The structure and mechanism of the conventional CRT shown in FIG.
However, the CRT shown in FIG. 1 of the present invention is different from the conventional convex surface in that the structure of the cathode ray tube outer surface 11 is different and is a flat surface or a concave surface.

Conventionally, the display surface of a CRT has a convex surface. Firstly, the inside of the CRT is a vacuum, and a stress is generated in the glass tube of the CRT due to the pressure difference between the internal and external pressures. In order to prevent the pipe from breaking, it must be convex when viewed from outside the pipe.
In addition, when the curvature of the tube surface is small and the distance from the electron gun is different depending on the location, distortion occurs in the image projected by the deflection of the electron beam and it becomes difficult to focus the electron beam. ing.

Therefore, in the present invention, as shown in FIG.
The surface of the fluorescent material that emits light when irradiated with an electron beam has a concave structure (convex when viewed from the outside of the tube) as in the conventional case, and the outside surface of the tube has a flat or concave structure and is sandwiched between both surfaces. Due to the action of the concave lens structure thus constituted, the image projected on the fluorescent surface is made closer to a flat surface.

FIG. 3 shows the action and effect. The glass tube sandwiched on both sides fulfills the action of a concave lens because the fluorescent surface side is concave and the outer surface of the tube is flat or concave. . There is a fluorescent body on this one surface, and the image formed by electron beam irradiation on it has an optical image plane that is raised in the direction of the viewpoint when viewed from outside the tube due to the refractive index of glass. . That is, the image formed by the electron beam at the point A in FIG. 3 is optically formed at the point A ′ by the action of the concave lens.

The movement of this image forming point is substantially proportional to the refractive index of the glass and the thickness of the glass at that point, so that the curvature of the optical image forming surface is smaller than that of the fluorescent body surface, that is, the radius of curvature is large. It's closer to a plane.

Here, the outer surface of the tube may be a concave surface, and the curvature of the optical image forming surface may be 0, that is, a flat surface as the curvature is increased.

Next, FIG. 4 shows the effect of preventing the reflection of external light by making the outer surface of the CRT concave. When the tube surface is convex, a wide range of external light is reflected by the convex mirror effect. Then, it becomes narrower, and when it is made concave, its radius of curvature is equal to the viewpoint, and when viewed from its center point, the reflection is completely eliminated (in principle, one point of the viewer's pupil is the entire tube surface. Reflected in).

Of course, since the viewer does not look exactly from the center point, the reflection cannot be completely eliminated, but when the radius of curvature is set to the optimum viewpoint distance, the reflection of external light is greatly reduced. It

Furthermore, as another effect, as shown in FIG. 5, pincushion distortion in which an image of four corners of the tube surface spreads outward due to the flattening and wide deflection angle of the CRT is reflected by the concave lens action. It is possible to reduce.

As another effect, when the tube surface is convex, it cannot be stably placed, but the flat outer surface allows stable placement, and handling of the CRT during assembly and the like. Will be easier. Further, the concave surface has an effect that the display surface does not come into direct contact with the storage space, and thus scratches are less likely to occur.

The above has realized the structure of the concave lens by the CRT glass tube itself of FIG. 1, but in order to obtain such a structure, the tube manufacturing process and the jig must be recreated at all, and There is also the problem of making the tube itself heavy.

Therefore, as shown in FIG. 6 and FIG.
It is also possible to use a conventional tube for T itself and arrange a concave lens made of glass or plastic on the entire surface to give the same effect.

In this case, when the lens is made of plastic, it is more easily scratched than glass, and the outer surface of the plastic concave lens is protected by glass as shown in FIG. 7, and in some cases, the glass is provided with a Fresnel lens structure. The effect of the concave lens can also be enhanced by making it.

The structure of this Fresnel lens can be formed on the surface of the lens body 7 to give the same effect.

When such a tube and a lens are separately manufactured, they may be adhered to each other and handled as one body, or may be filled with silicone oil, silicone grease or the like without being adhered.
It is also possible to devise a method for preventing reflection on the boundary surface between external light and an image due to a change in refractive index.

[0027]

As described above, according to the present invention, it is possible to realize flattening of an image displayed by a cathode ray tube (CRT) so as to improve the structure without lowering the structural strength and distortion of the image. It is possible to reduce the reflection of external light, and
It can be placed stably in the assembly process of TVs, etc., and it is possible to obtain effects such as scratches on the display surface.
The effect is enormous.

[Brief description of drawings]

FIG. 1 shows a structure of a cathode ray display tube according to an embodiment of the present invention.

FIG. 2 shows a structure of a conventional cathode ray display tube.

FIG. 3 shows the optical action and effect of the embodiment of the present invention.

FIG. 4 shows the structure and operation of the entire surface of the display tube of the embodiment of the display invention.

FIG. 5 shows the optical action and effect of the embodiment of the present invention.

FIG. 6 shows the structure of the second embodiment of the present invention.

FIG. 7 shows the structure of the third embodiment of the present invention.

[Explanation of symbols]

1. ． Cathode ray display tube, 2. ． Shadow mask, 3. ． Fluorescent body, 4. ． Electron beam, 5. ． Electron gun, 6. ． Deflection coil, 7. ． Additional lens body, 8. ． Fresnel lens

Claims (8)

[Claims] 1. A cathode ray display tube characterized in that a member having a concave lens structure is provided on the front surface of an image display surface. 2. The cathode ray display tube according to claim 1, wherein an outer surface of the glass body of the cathode ray display tube has a curvature different from that of an inner surface of the display surface, which is a fluorescent material coating surface, and the concave lens structure is formed by glass bodies sandwiched on both sides. A cathode ray display tube comprising the above member. 3. The cathode ray display tube according to claim 2, wherein the outer surface of the display surface is a concave surface. 4. The cathode ray display tube according to claim 3, wherein a radius of curvature of the display outer surface is set to an optimum viewing distance. 5. The cathode ray display tube according to claim 1, wherein the member having the concave lens structure is constituted by a lens separated from the cathode ray display tube. 6. The cathode ray display tube according to claim 5, wherein the member of the concave lens structure is a plastic. 7. The cathode ray display tube according to claim 6, wherein the surface of said plastic lens is coated with glass. 8. The cathode ray display tube according to claim 7, wherein at least one surface of the coated glass and the plastic lens has a Fresnel lens structure.