JPS6047696B2 - picture tube - Google Patents

Description

[Detailed description of the invention] The present invention relates to a picture tube.

Normally, the panel, which is the image surface of the picture tube, is made of convex glass, and when ceiling lights and window light hit the panel, specular reflection from the convex mirror occurs, causing the TV viewer to see a smaller image. It appears as a shining image, so-called luster,
In addition, the image of the observer and surrounding objects appear as shadows.

Particularly when the image plane shows a dark scene such as a night scene, the gloss and the TV image from the image plane appear superimposed, giving the viewer a sense of discomfort. Conventionally, various means have been proposed to prevent this gloss (dazzle), and some of them have been put into practical use.

One method is to roughen the surface of the picture tube glass panel like frosted glass and coat it with a light-absorbing material.

With this method, the external light image is diffused and blurred, and its luster decreases, but the brightness of the bright parts of the external light image hardly decreases, and the TV image from the screen is also diffused on the panel surface, resulting in improved sharpness. The disadvantage was that the value decreased. The second method is to adhere a front protection transparent plate coated with an antireflection film used in optical lenses and the like to the surface of the picture tube panel glass.

According to this method, the sharpness deteriorates, the glossy bright areas become dark and dark, and there are various difficulties in producing a large area antireflection film, and the cost is high.
The present invention provides a method that overcomes the above drawbacks.

That is, by forming the outer surface of the picture tube into a concave structure, gloss can be prevented without roughening the surface of the glass panel or applying any substance. An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the configuration of a picture tube in one embodiment of the present invention. 1 is the main body of the picture tube, which may be either a color tube or a black and white tube.

2 is a glass panel of the picture tube, and 3 is a fluorescent surface coated on the inner surface of the glass panel.

Reference numeral 7 denotes a transparent or semi-transparent panel having concave shapes on both sides, having a refractive index equal to or close to that of the glass panel 2, and made of acrylic resin, for example.

8 is the inner surface of the transparent panel 7 having the same curvature as the outer surface 5 of the glass panel 2, and 9 is the outer surface of the panel 7. As will be described in detail later, the curvature is selected to suit the purpose of the present invention.

A transparent adhesive 6 is used to bond the glass panel 2 and the transparent panel 7 of the picture tube 1, and is an adhesive having a refractive index equal to or close to that of the glass panel 2. For example, polyester resin is used.

The purpose of the present invention is to reduce the surface reflection of the outer surface 5 of the glass panel 2,
The purpose is to move it onto the outer surface 9 of the transparent panel 7 to replace convex reflection with concave reflection.

Therefore, the glass of the glass panel 2, the adhesive 6, and the transparent panel 7 need to be made of the same medium. Therefore, the refractive index of the glass panel 2, the refractive index of the adhesive 6, and the refractive index of the transparent panel 7 must be the same or as close as possible. Note that, without using the adhesive 6, the transparent panel 7 and the glass panel 2 may be mechanically adhered so that there is no space.

Although the explanation so far has been about the method of bonding the transparent panel 7 to the glass panel 2, manufacturing the transparent panel 7 may be difficult.

In this case, as shown in Figure 2, the radius of curvature of the outer surface of the panel 2 is large and it is much closer to a flat surface than a curved surface.
A plano-concave transparent panel 70 with a flat outer surface and a concave inner surface is manufactured, and its inner surface is selected to have a smaller radius of curvature (than the radius of curvature of the outer surface of the panel 2). ) and adhere it to the picture tube 1. When bonded in this manner, the flat outer surface of the transparent panel 70 becomes a desired curved surface. In the above explanation, the transparent panels 7 and 70 are bonded to a normal picture tube, but as shown in FIG. Good too.

The method of gluing a transparent panel onto a normal picture tube sometimes involves complicated steps.

For this reason, the glass panel 20 itself is designed and press-molded in the shape shown in FIG. 3, taking into account strength against atmospheric pressure and minimizing the weight increase associated with it.
Coating the glass panel 20 with a phosphor. Frit sealing with cloth or funnels can be performed without increasing the number of steps in the normal picture tube manufacturing process. If the picture tube is manufactured from the beginning using the glass panel 20 shown in FIG. 3 in this manner, the effect of the present invention will be achieved once the picture tube is completed, reducing the number of man-hours and being highly economical. In addition, since the panel parts are made of the same medium (glass), regular reflection of external light occurs only in the concave part of the outer surface of the picture tube.
The effects of the present invention are significant.

Based on this configuration, the causes of gloss and the principles of countermeasures will be explained. The generation of gloss will be explained using FIG. 4.

For example, is the outer surface of the picture tube panel 1? Radius for picture tube is 538
It has a curvature of TWL. Light coming from outside is reflected by the outer surface of the panel, and light entering the inner surface is reflected by the fluorescent surface.
The reflection on the fluorescent surface becomes diffused reflection and the image is completely blurred, so it is ignored. The reflection on the outer surface of the panel is regular reflection, and since the curved surface is convex, it can be said that it is a low contrast convex mirror whose back surface is lined with a white diffusing surface made of fluorophore. To explain with reference to FIG. 4, as is well known, the image 11 incident on the convex mirror 15 produces an erect virtual image 1' between the focal point F of the convex mirror and the center Z of the convex mirror.In other words, the image at infinity is focused as a light point. Virtual image 1 appears on F as it approaches mirror 15.
"The image gradually becomes larger and approaches the center Z, and finally becomes a virtual image at the center Z that is the same size as the real thing. In other words, a wide range of external scenery is reduced and projected on the picture tube surface.Reflected image The fact that the image is reduced in size and appears shiny means that it feels brighter than when looking at an equal-sized light-emitting surface, where the luster appears as a bright spot.These developments make the viewer aware of the presence of the picture tube. In order to eliminate this drawback, the panel of the picture tube should be made into a concave mirror in order to enlarge or infinity the external image.As shown in FIG. 5, in the concave mirror 25, An object at infinity becomes a point at the focal point f as an inverted real image.As the object 21 approaches the center of curvature U of the concave mirror from infinity, the inverted real image 2 gradually becomes larger and approaches the center of curvature C, and the center of curvature U This results in an inverted real image 22'' that is the same size as the object 22. As the object 23 moves from the center of curvature C toward the focal point f, the inverted real image 23'' expands, and when it reaches the focal point f, the inverted real image becomes an infinite image at infinity. The vertical virtual image 24'' becomes a virtual image 24'' of twice the size at a position f/2 from the infinity size at negative infinity, and becomes an equal-sized virtual image at the center Z.

The curvature of the concave mirror when the picture tube panel is made into a concave mirror is determined by the following consideration.

If the external image captured on the picture tube is enlarged to about twice the size or more, it becomes difficult to recognize the shape of the object and it becomes difficult to be conscious of it. Therefore, if the position of a ceiling light, window light, observer, etc. is in the range f/2 from the center of curvature U, especially around f/2 around the focal point f, the outside image will be more than twice as large. desirable. That is, if the radius of curvature is C, then since C=7, the radius of curvature C should be determined so that the outside scene is located within the range of 114C to 314C. Observation conditions for television receivers vary widely and cannot be generalized.A typical example is that the distance from the receiver to the electric light on the ceiling is 1~3rrL.
The distance from the picture receiver to the window is about 3 to 67n, and these appear as gloss on the convex picture tube. In addition, the image of the observer himself is not a luminous object, but is a matter of concern because it appears as a reduced shadow. However, it is said that the suitable viewing distance for a television image is about 7 to 1 height of the picture tube height H, so the viewer should be positioned at a position of about 0.5 to 5 meters, depending on the size of the picture tube. It would be good to think that it is. Taking these conditions into consideration, it is appropriate to select the radius of concave curvature C of the picture tube of the present invention to be approximately C=1 to 107n (f=0.5 to 5 m) as shown in Table 1.

As mentioned above, by making the surface of the picture tube concave with a large radius of curvature, the external image can be enlarged from about twice to infinity to a virtual image, making the TV viewer unaware of the external image. becomes possible.

Furthermore, since the present invention has a simple configuration, it is also highly economical. The present invention is not only applicable to all current monochrome picture tubes, color picture tubes, and observation tubes, but also applicable to all existing monochrome picture tubes, color picture tubes, and observation tubes.
:5 high-definition television picture tube.

Note that the present invention is applicable not only to cases where the outer surface of the picture tube is spherical;
Needless to say, the present invention can be easily applied to a cylindrical picture tube.

[Brief explanation of the drawing]

1, 2 and 3 are sectional side views showing a picture tube according to an embodiment of the present invention, and FIGS. 4 and 5 are diagrams illustrating the principle of the present invention. No. 1... Picture tube, 2, 20... Panel, 3
...Fluorescent surface, 6...Adhesive, 7,70
...Transparent panel.

Claims (1)

Claims: 1. A picture tube characterized in that the front surface is formed into a concave surface, and the radius of curvature C of the concave surface is set so that the distance between the reflecting object and the screen satisfies 1/4C to 3/4C. 2. The picture tube according to claim 1, wherein a transparent or translucent panel having a refractive index equal to or close to that of the glass panel is adhered to the outer surface of the glass panel so that the front surface is concave. 3. The picture tube according to claim 1, wherein the front surface of the glass panel itself is concave.