JP3133367B2 - Method for forming phosphor screen of color picture tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a fluorescent screen of a color picture tube, and more particularly to a method of forming a fluorescent screen of a color picture tube with an improved exposure method for forming a black stripe type fluorescent screen.

[0003]

2. Description of the Related Art In general, a color picture tube is provided with a shadow mask having a large number of openings formed inside a panel facing a phosphor screen formed on the inner surface of a panel, and is provided with an electron beam emitted from an electron gun. By scanning the fluorescent screen through the opening of the shadow mask, a color image is displayed on the fluorescent screen. In such a color picture tube, in particular, a plurality of slit-shaped apertures are arranged in a row via a bridge in a shadow mask, and the aperture rows are formed in parallel, and corresponding to the apertures of the shadow mask, As shown in FIG. 4, a black stripe type light absorbing layer 1 in which a phosphor screen is formed with stripe-shaped gaps in parallel.
In some gaps, three-color phosphor layers 2B, 2G, and 2R in a stripe shape emitting blue, green, and red light are formed in parallel to form a black stripe-type phosphor screen.

Usually, this black stripe type fluorescent screen is
It is formed by forming a light absorbing layer by a photographic printing method and then forming a three-color phosphor layer in the stripe-shaped gap. The light absorbing layer forms a resist film by forming a photosensitive film on the inner surface of the panel, exposing the photosensitive film through a shadow mask to print and develop a pattern corresponding to the opening of the shadow mask, It is formed by applying a black paint and then peeling off the black paint on the resist film together with the resist film. The three-color phosphor layer is formed by forming a phosphor slurry layer containing a phosphor and a photosensitive agent as main components, and exposing the phosphor slurry layer through a shadow mask to form a pattern corresponding to the opening of the shadow mask. Is formed by baking and developing.

In the light exposure for forming the light absorbing layer and the phosphor layer of the black stripe type fluorescent screen, the light absorbing layer is formed by a continuous stripe-shaped gap corresponding to a bridge between slit-shaped openings of the shadow mask. , and to form the phosphor layer for likewise unbroken stripes, the array direction of the slit-shaped apertures arranged through the bridge, that is used is a linear light source to the aperture columns in the longitudinal direction I have.

As shown in FIG. 5, the length of the light source is usually L, the distance from the inner surface of the panel to the light source, q is the distance from the inner surface of the panel to the shadow mask, and PV is the slit shape arranged via a bridge. When the arrangement pitch of the apertures, n, is a natural integer, the length is determined by Expression (1).

[Equation 1] Le = n · (L / q) · PV (1) However, the light absorbing layer and the phosphor layer are formed by using light sources of the same length. Then, since the thickness of the photosensitive film for forming the light absorbing layer and the thickness of the phosphor slurry layer for forming the phosphor layer are significantly different, a considerably different effect of the length Le of the light source appears. That is, the thickness of the photosensitive film for forming the light absorbing layer is usually 1 μm or less, but the thickness of the phosphor slurry layer for forming the phosphor layer is several tens of μm.
The light image formed on the thin photosensitive film is sharp, but the light image formed on the phosphor slurry layer is scattered and blurred. Occurs. In the case of the light absorbing layer, if the length is deviated from the appropriate length determined by the expression (1), the constriction corresponding to the bridge of the shadow mask appears remarkably.
No clear difference appears due to the light image scattering described above. However, in the case of the phosphor layer, when observing the state of the stripe using the amount of exposure as a parameter, when the constriction occurs, a part of the phosphor layer is raised (usually called up),
When the exposure amount is further reduced, a part of the phosphor layer starts to peel off.

On the other hand, as a problem in the phosphor layer forming step,
There is chipping at the tip of the stripe peculiar to the stripe-shaped phosphor layer. This chipping is the peeling of the phosphor layer at the tip of the stripe, and sometimes not only the chipping but also a part of the peeled phosphor layer may overlap the adjacent other color phosphor layer. When a part of the phosphor layer is peeled off in this manner, the part does not emit light and becomes a defect of the phosphor screen. In addition, when it overlaps with the phosphor layer of another color, the color purity is degraded, and when it is poor, it is degraded even to the white uniformity.

Conventionally, when chipping of the stripe tip starts to occur, the exposure time is extended to increase the stripe size, the drying of the phosphor slurry layer is enhanced, and the thickness of the phosphor slurry layer is reduced. Means prevent chipping, but increasing the stripe size is likely to cause so-called fogging, and strengthening the drying of the phosphor slurry layer is likely to cause thermal fogging, and further increasing the film thickness of the phosphor slurry layer. Reducing the thickness has adverse effects such as lowering the luminance, and there is no practically effective means.

[0010]

As described above, as a method of forming a black stripe type fluorescent screen of a color picture tube, when a light absorbing layer and a phosphor layer are formed by using a light source of the same length, light absorption is difficult. Since the thickness of the photosensitive film for forming the layer and the thickness of the phosphor slurry layer for forming the phosphor layer are significantly different, the influence of the length of the light source is considerably different. That is, since the photosensitive film for forming the light absorption layer is thin, if the length of the light source is not appropriate, the constriction corresponding to the bridge of the shadow mask appears remarkably. In contrast,
Since the phosphor slurry layer for forming the phosphor layer has a large film thickness, an optical image is scattered, and constriction corresponding to a bridge hardly appears. However, in the case of the phosphor layer, floating occurs in a part of the phosphor layer when the constriction occurs, and when the exposure amount is further reduced, a part of the phosphor layer starts to peel off. On the other hand, as a problem in the phosphor layer forming step, there is chipping due to peeling of the phosphor layer at the tip of the stripe peculiar to the stripe phosphor layer. When this chipping occurs, the chipped part does not emit light and becomes a fluorescent screen defect, and when a part of the peeled phosphor layer overlaps with the adjacent other color phosphor layer, the color purity is deteriorated,
When the degree is poor, it deteriorates even to the white uniformity.

For this reason, conventionally, when the tip of the stripe is chipped, the exposure time is extended to increase the stripe size, the drying of the phosphor slurry layer is enhanced, the thickness of the phosphor slurry layer is reduced, and the like. However, increasing the stripe size tends to cause so-called fogging, and enhancing the drying of the phosphor slurry layer tends to cause thermal fogging, and further increasing the thickness of the phosphor slurry layer. There is a problem that lowering the luminance leads to a decrease in luminance, and practically effective means have not been found.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an improved exposure method for forming a light absorbing layer and a phosphor layer of a black stripe type phosphor screen to prevent the occurrence of a phosphor screen defect. It is another object of the present invention to obtain a phosphor screen forming method capable of improving phosphor screen quality and manufacturing yield.

[Structure of the Invention]

[0014]

A plurality of slit-shaped apertures are formed on the inner surface of a panel by a linear light source arranged in a longitudinal direction with the arrangement direction of the apertures through a shadow mask arranged in a row through a bridge. Expose the exposed photosensitive film, while forming a black stripe type light absorbing layer by baking a pattern corresponding to the opening on the photosensitive film, and exposing the phosphor slurry layer formed on the inner surface of the panel, In a phosphor screen forming method of a color picture tube that forms a striped phosphor layer by baking a pattern corresponding to the opening on the phosphor slurry layer, the light source length when forming a light absorption layer, When forming the phosphor layer, a linear light source having a short light source length was used.

[0015]

As described above, when the phosphor layer is formed, if a linear light source having a shorter light source length than the light source length when forming the light absorbing layer is used, the photosensitive film when forming the light absorbing layer is used. Compared to the light image above, the penumbra of the light image on the phosphor slurry layer can be made smaller, the umbrella part can be made larger and the size of the stripe-shaped phosphor layer can be enlarged, and the tip of the stripe-shaped phosphor layer peels off Can be prevented.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings based on embodiments.

As a result of closely examining the chipping due to peeling of the stripe-shaped phosphor layer tip of the black stripe type phosphor screen, the size of the chipping was determined by the arrangement of a plurality of apertures arranged via the bridge of the shadow mask. The maximum number of holes is 1/2 or less of the arrangement pitch of the openings in the direction, and is at most about 1 pitch. 30 to 40 with respect to the vertical axis passing through the center of the panel
It was found that the phosphor layer was more likely to occur in the peripheral portion of the panel near the tilted axis, and the chipping easily occurred in the peripheral portion of the panel, in which the thickness of the phosphor layer was about 5% thicker than in other portions. Further, it has been found that a case where the distance from the inner surface of the panel to the shadow mask is large is likely to occur.

Therefore, as a result of studying means for preventing the occurrence of chipping based on these facts, as a result, when the phosphor slurry layer formed on the inner surface of the panel is exposed through a shadow mask, the light obtained on the phosphor slurry layer is exposed. The penumbra portion of the image is greatly involved, and if the penumbra portion of this light image is reduced,
It was concluded that chipping of the phosphor layer tip could be largely prevented.

In order to reduce the penumbra of the light image, at the time of exposure, the arrangement direction of the plurality of openings arranged via the bridge of the shadow mask, that is, the arrangement direction of the openings is set as the longitudinal direction. It has been confirmed that the length of the light source may be shortened, and the chipping of the tip of the phosphor layer can be considerably improved as the length of the light source is shortened. On the other hand, when the length of the light source is shortened, the constriction generated corresponding to the bridge of the shadow mask increases, resulting in a defective fluorescent screen.

As a result of the experiment, as shown in FIG. 1A, when the photosensitive film for forming the black stripe type light absorbing layer is exposed, the light source 4 which does not cause a constriction corresponding to the bridge of the shadow mask 5 is exposed. For the proper length Leb,
When exposing the phosphor slurry layer for forming the stripe-shaped phosphor layer, as shown in FIG. It has been found that the chip at the layer tip can be eliminated and the constriction corresponding to the bridge of the shadow mask 5 can be made inconspicuous. That is, assuming that the appropriate length of the light source when exposing the photosensitive film for forming the black stripe type light absorbing layer is n = 2 in the equation (1), the fluorescent light for forming the stripe-shaped phosphor layer is formed. When exposing the body slurry layer, it is preferable to use a light source having a length of n = 1 in the equation (1).

In FIGS. 1 (a) and 1 (b),
3 is a panel.

Next, a method of forming a black stripe type fluorescent screen using the above light source will be described.

As shown in FIG. 2A, a photosensitive agent containing polyvinyl alcohol (hereinafter referred to as PVA) and ammonium dichromate (hereinafter referred to as ADC) as main components is applied to the inner surface of the panel 3 and dried. A photosensitive film 10 is formed. Next, as shown in (b), the longitudinal direction is set through the shadow mask 5 in which a plurality of slit-shaped openings are arranged in a row via the bridge, and the arrangement direction of the openings 11 arranged through the bridge is arranged. Exposure is performed by the linear light source 4 having the length Leb (see FIG. 1A), and a pattern corresponding to the opening 11 of the shadow mask 5 is printed on the photosensitive film 10. Next, as shown in (c), development is performed to remove unexposed portions, and a resist film 12 having a stripe-shaped gap is formed. Next (d)
As shown in FIG. 3, the panel 3 on which the resist film 12 is formed is formed.
After a black paint is applied to the inner surface and dried to form a paint layer 13, as shown in (e), the resist film and the paint layer thereon are peeled off to form a black stripe having a stripe-shaped gap portion 14. The light absorption layer 1 is formed.

Thereafter, as shown in FIG. 3A, a phosphor slurry containing, for example, blue phosphor, PVA and ADC as main components is applied to the inner surface of the panel 3 on which the black stripe type light absorbing layer 1 is formed. And dry the phosphor slurry layer 16
To form Next, as shown in FIG.
The openings 11 arranged through the shadow mask 5 used when exposing 10 and the bridge of the shadow mask 5
The phosphor slurry layer 16 is exposed by a linear light source 4 (see FIG. 1B) having a length of Les arranged with the arrangement direction as a longitudinal direction, and is exposed to the blue phosphor layer forming position in the stripe-shaped gap. Then, a pattern corresponding to the opening 11 of the shadow mask 5 is printed. Next, as shown in (c), development is performed to remove the unexposed portions, and a stripe-shaped blue phosphor layer 2B is formed in the stripe-shaped gap at the position where the blue phosphor layer is formed. Thereafter, the method for forming the blue phosphor layer 2B is repeated for the green and red phosphors, and as shown in FIG. 2G and the red phosphor layer 2R are formed.

As described above, when the black stripe type light absorbing layer 1 is formed, n = 2 and (1)
Exposure is performed using the linear light source 4 having the length Leb determined by the formula to form the stripe-shaped three-color phosphor layers 2B, 2G, and 2R, where n = 1 and Le determined from the formula (1).
When exposure is performed using the linear light source 4 having a length Les shorter than b, the light source has the same length as the linear light source when forming the light absorbing layer as in the related art, that is, in this case, n = 2 and ( 1) Compared to the case where a stripe-shaped phosphor layer is formed by using a linear light source having a length determined by the formula, the penumbra portion of the light image on the phosphor slurry layer is reduced, and conversely, the umbra portion Is increased, the size of the stripe-shaped phosphor layer can be increased, and chipping at the tip of the stripe can be almost completely prevented.

In the above embodiment, the length of the linear light source when forming the stripe-shaped phosphor layer is set to the length determined by the equation (1), where n = 1, and The length of the linear light source when forming
= 2 and the length determined by equation (1). In this case, the length of the linear light source when forming the black stripe type light absorption layer 1 is such that n is an integer of 2 or more (3, 4, 4).
..) May be the length determined by equation (1). In other words, when the length of the linear light source when forming the striped phosphor layer is 1, the length of the linear light source when forming the striped phosphor layer is 0.5 to 0.9. Thereby, chipping of the stripe-shaped phosphor layer tip can be almost completely prevented as in the above-described embodiment.

[0027]

According to the present invention, when forming a black stripe type phosphor screen, a linear light source having a short length is used when forming a stripe type phosphor layer with respect to the light source length when forming the black stripe type light absorbing layer. When used, the penumbra portion of the light image on the phosphor slurry layer is made smaller and the umbra portion is made larger with respect to the light image on the photosensitive film when the light absorbing layer is formed, and the stripe-shaped phosphor layer is formed. size can greatly, the Stra
Chipping of the tip of the ip- shaped phosphor layer can be almost completely prevented.

[Brief description of the drawings]

FIG. 1A is a view for explaining a light source length for forming a black stripe type light absorbing layer according to an embodiment of the present invention, and FIG. It is a figure for explaining the light source length for forming.

FIGS. 2A to 2E are explanatory views of a method of forming the black stripe type light absorbing layer.

FIGS. 3A to 3D are explanatory views of a method of forming the stripe-shaped phosphor layer.

FIG. 4A is a plan view showing a structure of a black stripe type fluorescent screen, and FIG. 4B is a bb sectional view thereof.

FIG. 5 is an explanatory diagram of the length of a light source used when forming a black stripe type fluorescent screen.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Black stripe type light absorption layer 2B, 2G, 2R ... Striped three-color phosphor layer 3 ... Panel 4 ... Linear light source 5 ... Shadow mask 10 ... Photosensitive film 11 ... Slit-shaped aperture 16 ... Phosphor slurry layer

Claims (1)

(57) [Claims] 1. A photosensitive film formed on an inner surface of a panel by a linear light source having a plurality of slit-shaped openings arranged in a line through a bridge and arranged in a line with a shadow mask arranged in a line with the arrangement direction of the openings being a longitudinal direction. To form a black stripe type light absorbing layer by baking a pattern corresponding to the opening on the photosensitive film, and exposing the phosphor slurry layer formed on the inner surface of the panel to expose the phosphor slurry. In a method for forming a phosphor screen of a color picture tube, which forms a stripe-shaped phosphor layer by baking a pattern corresponding to the opening in the layer, the phosphor is formed with respect to the light source length when the light absorption layer is formed. A method of forming a phosphor screen for a color picture tube, comprising using a linear light source having a short light source length when forming a layer.