JPH081781B2 - Color cathode ray tube screen forming method - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a screen forming method for a color cathode ray tube.

[Technical background of the invention and its problems]

The shadow mask type color CRT, as shown in FIG. 6, is a panel (2) that constitutes the front part of the envelope (1).
Opposed to the screen (3) formed on the inner surface, a spherical shadow mask (4) having a large number of electron beam passage holes regularly arranged inside thereof is provided. An electron gun (6) is arranged in the neck (5) on the back side of the shear mask (4). Then, this electron gun (6)
The required image is reproduced on the screen (3) by making the electron beam emitted from the electron beam passing through the electron beam passage hole of the shadow mask (4) incident on the required phosphor.

By the way, in the shadow mask (4), the area occupied by the electron beam passage holes is remarkably small with respect to the entire area thereof, and the electron beam incident on the fluorescent material is unknown. ) And heat it. On the other hand, the shadow mask (4) has a thickness of 0.
A large number of electron beam passage holes are formed in a thin steel plate of about 15 mm, which is further spherically shaped to form a mask body (7), and a frame (8) having high mechanical strength and large heat capacity is provided around the mask body (7). It is configured to be attached to the inside of the panel (2) by engaging the panel pin (9) attached to the inner surface of the panel (2) with the mask holder (10) attached to the frame (8). It is installed.

Therefore, when the shadow mask (4) is heated by the incidence of the electron beam, as shown by the alternate long and short dash line in FIG.
It bulges to the convex side and causes so-called doming. In this doming, the mask body (7) is heated by the incidence of the electron beam as shown by the alternate long and short dash line (11b) from the unheated initial state shown by the solid line (11a) in FIG. 7, and the heat capacity is larger than that. The frame (8) is not heated too much,
As a result, the mask main body (7) passes through a transient state in which the mask main body (7) bulges to the convex side, and
In addition to the mask body (7), the frame (8) is also heated,
The heating of the mask body (7) and the frame (8) and the heat dissipation from these are balanced, and the mask body (7)
And the frame (8) have a constant temperature difference (the mask body has a higher temperature than the frame) in a thermal equilibrium state. In this thermal equilibrium state, in the shear mask (4), not only the mask body (7) swells to the convex surface side, but also the frame (8) expands and is displaced in the lateral direction of the panel (2).

Usually, a screen (3) of a shadow mask type color cathode-ray tube has a photosensitive resin film or a phosphor slurry film composed of a photosensitive resin and a phosphor formed on the inner surface of the panel (2), and these films are formed at a temperature close to room temperature. It is formed by baking a desired pattern on the substrate through a shadow mask (4).

Therefore, if the color cathode ray tube having the screen (3) formed as described above is properly landed and adjusted without heating the shadow mask (4) mounted inside, the doming of the shadow mask (4) is performed. Corresponding to the change, the landing changes as shown in FIG. 9 (A). This FIG. 9 (A)
In the figure, the horizontal axis shows the screen of the black stripe type color cathode ray tube shown in FIG. 8 with the distance from the center of the screen to the periphery in the direction orthogonal to the longitudinal direction of the stripe as indicated by the arrow (12). The shift of the electron beam spot (14) with respect to the phosphor stripe (13) is represented along the axis as "+" when the shift is toward the center of the screen and "-" when the shift is toward the peripheral direction.

The landing of the electron beam on the phosphor is as shown by the solid line (15a) with respect to the initial state in which the landing is adjusted correctly, as the doming of the shadow mask (4) becomes a transient state or a thermal equilibrium state, and the dashed line (15b) ) And a two-dot chain line (15c) cause a landing shift. The amount of landing deviation changes depending on the electron beam current density, but the tendency does not change. Therefore, the actual color CRT is shown in Fig. 9 (B).
As shown by the double-dashed chain line (16c) in the figure, the landing adjustment is performed so that good landing can be obtained in the thermal equilibrium state. Therefore, as indicated by the solid line (16a) and the alternate long and short dash line (16b) in the figure, landing displacement occurs in the initial state and the transient state.

In order to improve the landing characteristics of the shadow mask (4) due to the doming, the shadow mask (4) heated to a predetermined temperature, that is, the domed shadow mask (4) is used to 2) There is a method of baking a pattern on the photosensitive resin film formed on the inner surface or the film of the phosphor slurry containing the photosensitive resin to form a screen.

As a method for heating the shadow mask (4), there is disclosed in
Japanese Patent Laid-Open No. 58-44651 and Japanese Patent Laid-Open No. 85-8067 disclose a method of heating by blowing warm air. However, the method of heating with warm air is such that
Further, local heating due to blown air occurs, and the temperature distribution of the shadow mask (4) becomes uneven, resulting in uneven doming.

Further, Japanese Patent Application Laid-Open No. 48-22269 discloses a method of heating by high frequency, but in this high frequency heating, due to the high frequency current flowing in the thick frame (8),
In the peripheral portion of the mask body (7), the temperature rise on the frame side is large, and temperature unevenness is likely to occur. Further, due to the expansion of the frame (8) due to the temperature rise, there is a problem that the doming tends to decrease.

Further, JP-A-58-175233 discloses a method of heating the shadow mask (4) with an infrared lamp. However, in this method, infrared rays are radiated through the panel (2) and part of the infrared rays is absorbed by the panel (2), so that the heating efficiency is reduced. There is also a problem that the temperature difference between the center and the periphery of the shadow mask becomes too large depending on the shape and arrangement of the infrared lamp.

Instead of the method of heating the shadow mask (4) to form a screen, as shown in FIG. 10, a lens (17) for correcting landing displacement due to doming of the shadow mask (4) is provided. Using an exposure device,
There is also a method of baking a desired pattern while keeping the panel (2) and the shadow mask (4) at the same temperature, but this method requires that the atmosphere temperature during baking be kept at a high temperature of about 30 to 40 ° C. It is not good for the working environment.

In short, the conventional method of heating the shadow mask (4) to form the screen (3) is an excellent method for obtaining a color cathode ray tube having a good landing characteristic, but the desired doming cannot be obtained and the desired landing characteristic is obtained. Can't get

[Object of the Invention]

An object of the present invention is to obtain a required landing characteristic in a screen forming method of a color cathode ray tube in which a shadow mask is heated to form a screen.

[Outline of Invention]

In the screen forming method of a color cathode ray tube that heats a shadow mask to form a screen, a shadow mask is attached to a panel heated to a predetermined temperature, the shadow mask is heated by radiant heat from this panel, and the mask body is removed from the frame. After entering a thermal equilibrium state with a temperature difference of 3-10 ° C, the pattern of the mask body is baked on the photosensitive resin-containing coating formed on the inner surface of the panel to easily form a screen with the required landing. I made it possible.

Example of Invention

Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

First, the screen forming process of the black matrix type color CRT will be described with reference to FIG. First, as shown in FIG. 1A, a photosensitive resin is applied to the inner surface of the panel (2), and the photosensitive resin is heated to coat the photosensitive resin (20).
The panel (2) is heated to 30 to 40 ° C. at the same time as the formation of the above. The panel (2) may be heated to the same temperature by heating the panel (2) after forming the photosensitive resin film (20), if necessary. Next, as shown in FIG. 3B, a shadow mask (4) is attached to the heated panel (2) and placed on an exposure device (not shown), and the attached shadow mask (4) is attached to the panel ( After the temperature is raised by the radiant heat from 2) to reach a thermal equilibrium state, the photosensitive resin film (20) is irradiated with light through the electron beam passage hole of the shadow mask (4) to burn a desired pattern. wear.

After that, remove the shadow mask (4),
After developing the photosensitive resin film (20), a film of a light absorbing paint is formed. Then, the exposed portion of the photosensitive resin coating film (20) is peeled off together with the light absorbing coating material applied thereon by a release agent, and further washed with water to form a stripe light absorbing layer.

Next, a phosphor slurry containing a photosensitive resin is applied and dried on the inner surface of the panel (2) having the light absorbing layer formed thereon, and the panel (2) is baked in the same manner as in the baking of the photosensitive resin coating film (20). Is heated to 30 to 40 ° C., a shadow mask (4) is attached, and after the shadow mask (4) is in a thermal equilibrium state, a desired pattern is printed. Then, the coating film of this phosphor slurry is developed to remove the unexposed portion, and a stripe-shaped phosphor layer is formed in the gap between the stripe-shaped light absorption layers.

Required screen, after forming the light absorption layer,
This formation of the photophosphor layer can be obtained by repeating the three-color phosphors of red, green and blue. In this screen forming step, when a desired pattern is printed on the photosensitive resin film (20) and the phosphor slurry film formed on the inner surface of the panel (2) through the shadow mask (4), the panel (2) is heated. Other than the above, it is the same as the known screen forming method that has been conventionally performed.

In FIG. 1, in this screen forming method, the panel (2) on which the photosensitive resin (20) is formed is heated to 35 ° C.,
Panel (2) and shadow mask (4) for an example of mounting a shadow mask (4) at 22 ° C on this
Shows the temperature change of.

As can be seen from this figure, since the panel (2) heated to 35 ° C. has a large heat capacity, it gradually decreases with time as shown by the straight line (22). On the other hand, since the mask body of the shadow mask (4) has a small distance from the panel (2) and a small heat capacity, it rises in a relatively short time due to the radiant heat of the panel (2) as shown by the curve (23). It heats up to a metastable state, after which the temperature rises slowly and approaches the panel temperature. However, since the frame has a larger distance from the side surface of the panel (2) than the distance from the panel (2) of the mask body and a large heat capacity, the curve (24)
The temperature is gradually raised as shown in.

As a result, the temperature difference between the mask body of the shadow mask (4) heated by the radiant heat of the panel (2) and the frame becomes a metastable state as shown by the curve (25) in FIG. Up to a relatively large value, but after entering the metastable state, there is a nearly constant temperature difference (stable temperature difference)
And the shadow mask (4) is in thermal equilibrium.
The pattern is printed on the photosensitive resin film (20) while the shadow mask (4) maintains this stable temperature difference, as indicated by the broken line (26) in the figure.

The stable temperature difference of the shadow mask (4) can be arbitrarily changed by the temperature difference between the first panel (2) and the shadow mask (4). However, the time until the stable temperature difference is reached (stable time) changes as shown by the curve (27) in FIG. Generally, in order to obtain a high stable temperature difference, it takes time for the temperature of the mask body to rise, and for the frame to slowly rise in temperature, it takes time.
It takes time to reach a stable temperature difference. In addition, the high stable temperature difference has a shorter duration than the low stable temperature difference, and the fluctuation within the pattern printing time for the photosensitive resin coating becomes large, which makes the screen formation unstable. The stable temperature difference that can be obtained in a relatively short time and that can be stably maintained is 10 ° C or less. In this temperature range, the pattern (2) and the shadow mask (4) are attached, and one minute later, the pattern is not baked. You can start.

On the other hand, the temperature difference (corresponding to a stable temperature difference) between the mask body and the frame in the thermal equilibrium state of the shadow mask type color cathode-ray tube and the maximum landing deviation amount due to the temperature difference have a constant relationship. FIG. 4 shows the relationship of a 21-inch color CRT in which a screen is formed by a usual method without heating the JADOW mask. In measuring the amount of landing deviation, changing the temperature difference between the mask body of the shadow mask and the frame can be easily performed by changing the current density of the electron beam incident on the screen and the shadow mask.

As can be seen from this drawing, the landing deviation amount with respect to the temperature difference changes linearly as shown by the center line (28). However, when the temperature difference approaches zero, the stress due to the difference in thermal expansion between the mask main body and the frame decreases, the change due to the manufacturing variation when assembling the shadow mask cannot be absorbed, and the variation in the landing deviation amount increases. However, the temperature difference in normal operation of the color CRT is 2 to
At 12 ° C., the variation of the landing deviation amount is almost constant in this range.

Therefore, from the above data, when the pattern is printed on the photosensitive resin film (20) formed on the inner surface of the panel (2), keep the stable temperature difference between the mask body of the shadow mask and the frame at 3 to 10 ° C. In this case, the required light absorbing layer can be stably formed, and similarly, the required phosphor layer can be stably formed between the light absorbing layers, and a screen having a good landing characteristic can be obtained.

Moreover, when the shadow mask (4) is heated by the radiant heat from the panel (2) as described above, it is possible to uniformly heat the mask body and the frame without locally heating them, and between the mask body and the frame. Therefore, a required temperature difference can be easily generated, and the shadow mask (4) can be subjected to the doming required for forming a required screen.

Further, by utilizing the radiant heat from the panel (2), the stable temperature difference between the mask body and the frame can be maintained for a long time, and the doming change during pattern printing can be reduced.

In addition, especially the stable temperature difference between the mask body and the frame is 3
At ~ 10 ° C, the time until the shadow mask (4) reaches a stable temperature difference becomes almost constant, so after attaching the shadow mask (4) to the panel (2), pattern baking can be started after a certain time. , Work management becomes easy.

〔The invention's effect〕

A shadow mask is installed on the panel heated to a predetermined temperature, and the radiant heat from this panel raises the temperature of the shadow mask, and after the mask body and the frame are in a thermal equilibrium state where a constant temperature difference is maintained, the inner surface of the panel is A predetermined pattern is baked on the photosensitive resin-containing film formed on the screen, and when the shadow mask type color CRT is operating, the shadow mask is heated by the incidence of the electron beam to form a screen in the same thermal equilibrium state. By doing so, it is possible to easily form a screen having good landing characteristics.

[Brief description of drawings]

1 to 5 are explanatory views of an embodiment of the present invention.
FIG. 2 is a diagram showing the relationship between a heated panel and the mask body and frame of a shadow mask that is heated by radiant heat from this panel. FIG. 2 is a diagram showing the temperature difference between the mask body and frame at that time. Fig. 3 shows the relationship between the time until the temperature difference between the mask body and the frame becomes constant and the stable temperature difference, and Fig. 4 shows that the shadow mask incorporated in the color CRT is heated by the electron beam incident. FIG. 5 is a diagram showing the relationship between the temperature difference between the mask main body and the frame and the amount of landing displacement when in a thermal equilibrium state, FIGS. 5 (A) and 5 (B) are diagrams for explaining the screen forming process, FIG. 6 is a diagram showing the structure of a shadow mask type color cathode ray tube, FIG. 7 is a diagram showing the doming of the shadow mask when heated by the incidence of an electron beam, and FIG. Shows a landing deviation with respect to the screen of the click stripe type color picture tube, 9
The figure shows the relationship between the doming of the shadow mask and the amount of landing deviation. (A) shows the figure when the landing adjustment is performed in the initial state where the shadow mask does not do, and (B) shows the shadow mask. FIG. 10 is a diagram illustrating a case where the landing adjustment is performed when the thermal equilibrium state is reached, and FIG. 10 is a configuration explanatory view of the exposure apparatus. (2) …… Panel, (3) …… Screen (4) …… Shadow mask, (7) …… Mask body (8) …… Frame, (20) …… Photosensitive resin coating

Claims (1)

[Claims] 1. A step of forming a photosensitive resin-containing coating on the inner surface of a panel of a color cathode ray tube and heating the entire panel to a predetermined temperature, and a peripheral portion of a mask body in which a large number of electron beam passage holes are formed in the panel. A shadow mask having a frame attached to it is mounted, and the shadow mask is heated by radiant heat from the panel heated to the predetermined temperature, and the mask main body has a temperature difference of 3 to 10 ° C. higher than that of the frame. And a step of baking a predetermined pattern obtained from the mask main body on the photosensitive resin-containing coating formed on the inner surface of the panel after the state is brought into a state, the method for forming a screen of a color cathode ray tube.