JPS6160534B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a phosphor surface of a color picture tube that selectively transmits the emitted color of a phosphor and selectively absorbs light coming from outside the screen.

In order to improve the contrast under brighter external light than ever before, a color picture tube has been proposed that has filter means for each of the phosphors that emit red, green, and blue colors when struck by an electron beam. . The function of the filter means is to selectively transmit the light emitted by the corresponding phosphor layer without changing its color, and selectively absorb light other than the light emitted by the phosphor among the light coming from outside the screen. Therefore, the amount of external light reflected on the screen surface is greatly reduced, improving contrast.

There are, for example, three methods for these filter means.The first method is to filter the phosphor layers between the phosphor screen surface and the inner surface of the glass panel, corresponding to the phosphor layers that emit red, green, and blue colors. It forms red, green, and blue filter material layers,
Red, green, and blue filter layers are formed using PVA + ADC + filter material or fritted glass + filter material. The second method is to coat the surface of phosphor particles with fine particle powder of a filter material corresponding to each emission color, and use these phosphors to form red, green, and blue filter layers. The third method is to form red, green, and blue filter layers by mixing corresponding filter materials in the phosphor layers that emit light in red, green, and blue on the inner surface of the glass panel.

However, when forming a filter layer using these methods, a major problem is the overall characteristics of reduced brightness and improved contrast due to the presence of the filter material. Contrast is of course dependent on the capabilities of the filter material used, but it is clear that contrast can be improved by increasing the amount of filter material used. On the other hand, as a result, the amount of light emitted from the phosphor absorbed by the filter material increases, and the rate at which the energy of the electron beam that should cause the phosphor to emit light is attenuated by passing through the filter material increases, resulting in an increase in brightness. decreases dramatically. However, the rate at which the energy of the electron beam is attenuated by the filter material greatly depends on the structure of the filter layer to be formed.

The first method is used to cause 100% of the phosphor particles to emit light without the energy of the electron beam being attenuated by the filter material, since no filter material is present in the phosphor layer. On the other hand, since the filter layer is located between the inner surface of the glass panel and the phosphor layer, the external light that passes through the glass panel is absorbed predominantly without penetrating to the phosphor layer, so the contrast is lower than the brightness reduction rate. The effect of improvement is significant.
However, before forming the phosphor layer, a filter layer must be formed in advance at the location where the phosphor of the corresponding luminescent color is to be printed, which has the drawback of increasing the number of steps. In addition, when forming a filter layer, the filter material tends to remain on the phosphor layer or the position where the filter layers of the other two colors are to be formed, and the former causes a color shift and a decrease in brightness, and the latter causes a decrease in brightness. has.

The second method uses a phosphor coated with a filter material, so that the filter material is uniformly distributed in the filter layer, and as mentioned above, the rate at which the energy of the electron beam is attenuated by the filter material is reduced. There will be more. Furthermore, in order to achieve the same improvement in contrast as in the first method, a larger amount of filter material must be present than in the first method, and this method has the disadvantage that brightness is greatly reduced compared to the improvement in contrast.

In the third method, a desired amount of filter material is mixed into a phosphor slurry and a filter layer can be easily formed using a conventional slurry method. However, since slurry recovery is involved, it is difficult to maintain a constant proportion of the filter material mixed in the phosphor layer, and as in the first method, the filter material is extremely small, so it may not be placed in a location other than the intended location. It has the disadvantage that it remains behind, causing color shift and a reduction in brightness. Furthermore, in order to obtain the same contrast as in the first method, a large amount of filter material must be present as in the second method, and there is a drawback that the brightness is greatly reduced compared to the improvement in contrast.

The method for forming a color picture tube fluorescent surface of the present invention improves the above-mentioned drawbacks, greatly simplifies the manufacturing method, minimizes brightness attenuation, and maximizes the effect of improving contrast. It's about doing.

That is, the present invention forms a filter layer using a conventional method using a phosphor slurry mixed with a filter substance, and the structure of this filter layer is such that the concentration is high on the panel side and low concentration on the electron gun side. It has characteristics.

The details of the present invention will be described below.

Suitable filter materials to be used include cadmium sulfide selenide and red iron sulfide for the red phosphor, cobalt green for the green phosphor, and cobalt aluminate and ultramarine for the blue phosphor. If so, you can use something instead of these.

A filter substance was added to distilled water to a concentration of 30 to 40% by weight, and a surfactant was added thereto, followed by glass bead milling to loosen the filter substance and simultaneously disperse it in an aqueous solution to obtain a filter dispersion. Here, the particle size distribution of the filter material in the dispersion can be controlled by the milling time and the concentration of the filter material in the aqueous solution. A desired amount of this filter substance dispersion is added to the milled phosphor dispersion, and after stirring well, polyvinyl alcohol (PVA) is added. Fluorescent material/
When the filter material and polyvinyl alcohol were well mixed, ammonium dichromate and various surfactants were added to form a filter material-mixed phosphor slurry.

First, a green phosphor slurry mixed with a green filter material is applied thinly and evenly to the inner surface of the glass panel using a spin coating method. After sufficiently drying, a light source that emits ultraviolet rays such as a mercury lamp is used to bake the phosphor at the position through a shadow mask. Burns a latent image onto the inside of the panel. Next, the non-exposed areas are dissolved using hot water to obtain a desired green filter layer. After sufficiently drying the obtained filter layer, diluted ammonia water is sprayed to dissolve the polyvinyl alcohol on the electron gun side of the filter layer, and remove the filter material contained therein and the filter material located outside the intended location. remove. After washing with water and thoroughly drying, blue and red filter layers are formed in this order in the same manner as above. The appropriate concentration of ammonia water used here is about 0.02 to 0.2%, and it is necessary to select the optimum concentration based on the processing time. Furthermore, in order to decompose the exposed polyvinyl alcohol, it is needless to say that not only ammonia water but also sodium hydroxide, potassium hydroxide, and other substances capable of obtaining similar effects may be used. Further, although the order of forming the filter layers is described here as green, blue, and red, a different order may be used. Possible methods for dissolving polyvinyl alcohol in the diluted ammonia water include spraying, dipping, and other appropriate methods.

As described above, after forming a filter layer using the conventional slurry method, the exposed polyvinyl alcohol is decomposed with aqueous ammonia to the extent that the filter layer does not come off, thereby removing the filter substance contained in the polyvinyl alcohol. . In other words, a filter layer with a low concentration on the electron gun side where a certain amount of the filter material was removed and a high concentration filter material distribution state in which a desired amount of filter material was mixed was formed on the inner surface of the panel. As a result, the energy attenuation of the electron beam due to the filter material is reduced, and the reduction in brightness is alleviated. Furthermore, since the filter material present in areas other than the intended areas is also removed, a fluorescent surface without color shift can be obtained.
The amount of filter material mixed in the filter layer can be controlled by applying a slurry containing a small amount of filter material while supplying a constant amount.

In this way, a filter layer with a structure similar to that in which a filter layer is provided between the inner surface of the panel and the phosphor layer can be obtained using a very simple method, and there is no color shift due to the filter material and there is no reduction in brightness. This is an excellent method as it provides a fluorescent surface with greatly improved contrast.

It goes without saying that this method of forming a fluorescent surface can be directly applied to forming a fluorescent surface of a color picture tube regardless of the presence or absence of a black material layer.

Further, in the above embodiment, a filter material was mixed in each of the phosphors that emit red, green, and blue, but this is not limited to three colors; for example, only blue, only red, etc. Needless to say, the present invention can be applied to cases where green is excluded from blue and red, or when at least one other phosphor is mixed with a filter substance corresponding to its emission color.

Claims (1)

[Scope of Claims] 1. A method for forming a color picture tube phosphor surface in which at least one of the phosphor layers that emits red, green, and blue colors upon impingement of an electron beam includes a filter material,
A step of forming a film on the inner surface of the panel by a slurry method by mixing a filter material corresponding to the emission color of the phosphor in a phosphor slurry containing a photosensitive agent forming the phosphor layer, and a step of forming a film on the inner surface of the panel through a shadow mask. exposing the film to light and dissolving the unexposed part;
A method for forming a color picture tube phosphor surface, comprising the step of forming a phosphor layer having a filter material distribution state of low concentration on the electron gun side and high concentration on the inner surface side of the panel. 2. The step of forming a phosphor layer having a filter substance distribution state in which the concentration is low on the electron gun side and high concentration on the inner surface side of the panel is that the surface of the phosphor layer on the electron gun side is coated with a photosensitive film decomposing agent. 2. A method for forming a color picture tube fluorescent surface according to claim 1, further comprising the step of dissolving the fluorescent surface of a color picture tube.