JPS6042581B2 - How to make a pattern for a graded type shadow mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a pattern manufacturing method for a crazet type shadow mask.

The manufacturing method of the shadow mask used in the shadow mask type picture tube for color television is to print a halftone dot pattern on an iron plate on which a photosensitive coating has been formed, and then to form through holes through a predetermined process such as phenomenon. Obtain the Shadow Mask.

The performance of the picture tube can be improved by forming the apertures of this shadow mask into a so-called graded mask, in which the diameter is large in the center of the effective surface of the mask and becomes successively smaller toward the periphery. It is. To form this graded type shadow mask, the method for attaching the marks is as follows: There are two methods: one is to grade the pattern itself for printing onto the plate, and the other is to grade the pattern after it is baked onto the metal plate from a two-dimensional uniform pattern.

The first method has conventionally been carried out as follows. That is, the device used in this case has a lamp 2, a milky white diffuser plate 3, and an aperture 4 disposed in a lamp house 1, as shown in FIG. A chromium-deposited filter 5, which is high in the center and becomes low toward the periphery, is fixedly placed, and a circular dot dry plate 6 having a transparent halftone dot group 8 as shown in FIG. This is a device that is disposed at the rear, and a photosensitive material 7 such as a film is fixed thereto. A lamp that serves as a light source for this device is turned on, and the light emitted from it passes through an aperture and irradiates the film, forming a pattern on the film.

However, when this method is used, the concentric difference in the transmittance of the vapor-deposited filter appears as a change in the pattern from the center to the periphery, and the disadvantage is that it is not sufficient to be used as a desired pattern for a shadow mask. be. The one shown in Figure 3 is an example of the transmittance curve of a conventional vapor-deposited filter. ), there is a difference of about ±1.5% on the concentric circles, and when printed as a pattern, it appears as a dimensional difference of 4 to 5p. This is undesirable because it causes unevenness in the product mask and lowers the quality of the color picture tube, that is, the white uniformity. For this purpose, the following apparatus is used for pattern formation. That is, a device as shown in FIG. 4 is used. Lamp house 11 as shown in the figure
A lamp 12 serving as a light source, a milky-white diffuser plate 13, and an aperture 14 are installed inside the lamp, and a light plate 15 is placed in front of the lamp 12, and a circular dot dry plate 16 and a photosensitive material 17 such as a film are fixed in front of the lamp 12. This is a device that is located at The shield light plate 15 in this device has a cutout hole 20 as shown in FIG. 5, and is attached to a frame 18, which is rotated by a rotating device 19. To form a pattern on a film using this device, a rotary device is driven to rotate a light plate attached to a frame, and the light emitted from the lamp passes through the holes in the light plate. The amount of light transmitted between the center and the periphery is continuously changed, and the thus changed light is irradiated onto the film, thereby burning a pattern onto the film. In this case, even if it is possible to reduce the difference in grade on concentric circles from the center, it is not possible to change the grade curve for each axis, and as with the filter method, a light plate is required for each product. Dej
However, due to the difficulty of manufacturing, there were problems with the quality and optionality of the grade of the mask.

This invention was made to eliminate the above-mentioned drawbacks, and a shield plate having an opening is disposed so as to be movable back and forth between the light source 3 and the photosensitive material. The present invention provides a method for forming a pattern of a desired grade.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 6 shows an example of an apparatus for forming a pattern for a graded type mask 4 or a shaded mask on a photosensitive material such as a film. A lamp house 21 is fixed to a lamp stand 22, and this lamp house 21 has a structure that cuts off light to the outside, and includes a lamp 23 as a light source, a condenser lens 24, and a milky white diffuser plate 25 therein. A diaphragm 26 is arranged in front of it, and further in front of the lamp house 21 a seven-sided shield plate 27 with a circular hole is arranged, which is attached to a moving device 30 driven by power. A pattern plate 2 having a uniform pattern of circular holes called halftone dots on the front side of this thin plate 27 opposite to the lamp house 21
A film 29 to which 8 is attached is placed. The shield plate 27 is moved back and forth between the film and the lamp house in the direction of the arrow by driving the moving device 30. To print a pattern on a film with such a device, a lamp in the lamp house is lit, and the light emitted from it passes through a condenser lens, a milky-white seven-color diffuser, and an aperture, and then passes through a circular hole in a shield plate. The light passes through, becomes circular light, and then passes through a pattern plate to reach the film, where a pattern is printed onto the film.

At this time, the moving device that holds the shield plate is driven and the film is irradiated with light from the light source while moving the shield plate, for example, from position A to KN, so the amount of light passing through the pattern plate is limited to the central part. Compared to when they are fixed, they can be changed continuously, and a desired graded pattern can be obtained. Further, the shield plate may be moved in the direction from A'' to A, or may be moved back and forth between A and A'', that is, between the lamp house and the film. Furthermore, by changing the time for moving a certain distance in this manner, patterns of different grades can be obtained as shown in FIG.
That is, a grade such as 1 in the figure can be given, or a grade such as 2 in the figure can also be given. As mentioned above, the amount of light can be changed arbitrarily by changing the way the shielding plate is moved, so the shielding plate can be suitably patterned with the desired grade required for various shadow masks. This can be easily obtained by moving it to

For example, a difference of 0 to 50p can be made between the central part and the peripheral part. In this way, according to the method of the present invention, a pattern that is extremely useful as a shadow mask pattern can be easily obtained. Next, an example will be described.

A 500W white lamp is used as the light source lamp, and the thickness of the milky white diffuser plate is 27r1f! 1, the aperture has a radius of 25 mm, and the radius of the opening in the shield plate is 25 wn. The pattern was photographed using halftone positive dots having a size of 100 μm and the displacement of the shield plate being 1.3rr1. The size of the circular light hitting a pattern plate with a uniform halftone dot group as shown in Figure 2 is as follows: The radius of the circle is 357 rrm.
It can be changed to a range up to 50wsL, and at this time the distance between the pattern board and the film is 2T! r! By setting the temperature at n, it was possible to print a pattern with an effective diameter of up to 600 mm on the film. The pattern at this time is 1 in the center.
30μ, with dimensions of 100μ at the periphery, thus approx.
I was able to get a grade of 0P. It goes without saying that in addition to the above-mentioned structure, other structures having modified structures can be obtained according to the gist of the present invention.

Furthermore, by changing the cut-out shape of the shield plate of this invention, the dot size grading curve, which could not be controlled using conventional methods using vapor-deposited filters, can be adjusted for each axis, for example. As shown in Figure 8,
It is possible to exhibit excellent effects in that each axis, Y axis, P axis, and Q axis can be controlled individually.

In other words, curve 1 in FIG. 8 is a grade ink curve for the X axis, curve 2 for the Y axis, and curve 3 for the P and Q axes, which can sufficiently accommodate the arbitrariness of the grade of the pattern. . As described above, according to the method of the present invention, it is possible to form a pattern that is successively smaller as desired from the center to the periphery without any error, and even for each axis. Different grade curve patterns can be obtained as desired. As a result, the quality of products using the shadow mask formed by the pattern according to the present invention is significantly improved, and there are great practical benefits.

[Brief explanation of the drawing]

Fig. 1 is a side view of a conventional graded type shadow mask pattern manufacturing device, Fig. 2 is a front view of a dot dry plate showing halftone positives, b is a side view, and Fig. 3 is a vapor deposition filter in the conventional device. FIG. 4 is a side view of another conventional graded shadow mask pattern manufacturing device, FIG. 5 is a front view of a shadow light plate used in the device shown in FIG. 4, and FIG. 6 is a diagram showing the transmittance curve of FIG. 7 is a perspective view showing an embodiment of the apparatus of this invention, FIG. 7 is a view showing an example of a graded pattern obtained by this invention, and FIG. 8 is a diagram showing each axis of size grading according to this invention. FIG. 3 is a diagram showing different patterns in FIG. 21... Lamp house, 23... Lamp, 24... Condenser lens, 25... Diffusion plate, 26... Aperture, 27... Conversion Hei board, 2
8... Pattern board, 29... Film, 3
0...Moving device.

Claims (1)

[Claims] 1. When producing a pattern for a graded type shadow mask, a shield plate with an opening is placed between a light source and a photosensitive material placed opposite to it, and a shield plate with an opening is placed between the light source and the photosensitive material. A method for producing a pattern for a graded shadow mask, characterized in that a pattern of a predetermined grade is obtained by controlling the amount of exposure that passes through the opening and reaches the photosensitive material while moving the shadow plate between the two.