JPH05120993A - Exposure light source unit - Google Patents

Abstract

PURPOSE:To manufacture a printing plate having less dispersion in pattern dimensions and good sharpness of pattern without generation of pin-holes. CONSTITUTION:An original plate 11 having opaque patterns in the places corresponding to the hole forming portions of a shadow mask and a raw dry plate 12 covered with a sensitive film not yet exposed are brought into vacuum contact to each other. An exposure light source 20 is moved in upward direction Yu and in downward direction Yd by a drive unit 21. The exposure light source 20 is a substantially linear light source is longer than one side with respect to the face of a mask pattern, and there is provided a lens unit including a number of focusing-type optical fibers arranged on the light exit side of the exposure light source. And then the exposure light source 20 is moved in upward direction Yu and in downward direction Yd by the drive unit 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a shadow mask for a color picture tube, and more particularly to an exposure light source device used for producing a printing plate of a shadow mask pattern which is one step of the shadow mask production.

[0002]

2. Description of the Related Art A shadow mask for a color picture tube has a large number of apertures, and an electron beam emitted from an electron gun is selectively applied to a screen having phosphors of three colors which emit red, green and blue respectively. It has a function of passing through so as to project, and is also called a color selection electrode.

This shadow mask is generally manufactured by a photoetching method. The schematic configuration of this step is as follows. That is, a step of forming a resist film on the surface of a flat continuous strip-shaped metal plate having a desired thickness,
A shadow mask pattern printing plate is closely arranged on both main surfaces of the metal plate, and an exposure step of baking a desired shadow mask pattern on a resist film using a light source such as ultraviolet rays, an unexposed portion of the resist film is heated with hot water or the like. It consists of a step of dissolving and removing by spraying, a step of performing a high-temperature heat treatment for enhancing the etching resistance of the residual resist film, and a step of spraying an etching solution to punch a shadow mask.

The production of a shadow mask printing plate used in the above-mentioned exposure step of printing a shadow mask pattern on a shadow mask material having a photosensitive film formed thereon is generally carried out as follows. First, with a pattern generator called a photo plotter, an original plate having an opaque pattern at a portion corresponding to a shadow mask hole forming portion is created,
After correcting the defective portion and the necessary portion of the original plate, the raw dry plate having an unexposed photosensitive film and the original plate are vacuum-contacted with each other, and light is irradiated using an exposure light source device, and the transparent part and the opaque part of the original plate are Create a pattern in which is reversed. A mask pattern is created by correcting the defective portion and the necessary portion of this pattern. The mask pattern is further vacuum-contacted with an unexposed dry plate to irradiate it with light, so that the inverted pattern becomes a shadow mask pattern printing plate having an opaque pattern at a portion corresponding to the shadow mask hole forming portion, With the mask pattern, it is possible to duplicate the required number of printing plates.

An exposure light source device conventionally used for vacuum contact reversal for producing the above shadow mask pattern printing plate uses a mercury lamp 1 as a light source, as shown in FIG. 7, and a mercury lamp for increasing the light source intensity. A reflecting mirror 2 is attached to the back of 1. On the light exit side, there are a diffuser plate 3 for erasing the image of the lamp and making the light intensity distribution uniform, a diaphragm 4 for optimizing the exposure amount and light distribution, and an automatic shutter 5 for controlling the exposure time. Installed. The emulsion of the glass plate used for the printing plate is mainly silver based, and the amount of change in the printing pattern size with respect to the exposure amount (light intensity × exposure time) is large. Therefore, it is required that the light distribution is uniform over the entire irradiation surface, but in order to obtain a uniform light distribution, either reduce the aperture area of the diaphragm or increase the distance between the light source and the irradiation surface. Is good. However, along with this, the light intensity on the light-irradiated surface decreases too much, and even if the exposure amount is increased by long-time exposure, the occurrence of pinholes due to insufficient exposure due to insufficient minimum light intensity required for exposure It cannot be avoided. On the other hand, if the light intensity is too strong, a fog phenomenon occurs in the silver-based emulsion, and it is necessary to separate the light source to obtain an appropriate light intensity on the irradiation surface, which causes a space problem. In particular, with the recent increase in the size of shadow masks used for ultra-large color cathode ray tubes and high-definition tubes, the area of the printing plate is increasing at an accelerating rate, and it becomes more and more difficult to obtain a uniform light distribution in proportion to it. It has become to.

Further, conventionally, there is a method of irradiating the entire surface to be irradiated by dividing the surface to be irradiated into a plurality of fields using a light source having a cylindrical light beam and scanning the light source along a predetermined track. It is disclosed in JP-A-61-126544. This is to irradiate the entire surface to be illuminated uniformly by overlapping and irradiating the boundary portion with a luminous intensity of 1/2 in order to prevent excess or deficiency of illuminance at the boundary portion of each divided field. Is what you are trying to do.

[0007]

As described above, in order to prepare a shadow mask printing plate, it is required that the light distribution be uniform over the entire irradiation surface during the exposure process. This is because the emulsion of the glass plate used for the printing plate is mainly silver based, and the amount of change in the baking pattern size with respect to the exposure amount (light intensity × exposure time) is large. In order to obtain a uniform light distribution, it is necessary to reduce the aperture area of the diaphragm or increase the distance between the light source and the irradiation surface, but with this, the light intensity on the irradiation surface decreases. Even if the exposure amount is increased by exposure for a long time, it is impossible to avoid the occurrence of pinholes due to insufficient exposure. On the other hand, if the light intensity is too high, the fog phenomenon occurs in the silver-based emulsion, and it is necessary to separate the light source to obtain an appropriate light intensity on the irradiation surface, which causes a space problem. In particular, with the recent increase in the size of shadow masks used for ultra-large color cathode ray tubes and high-definition tubes, the area of the printing plate is increasing at an accelerating rate, and it becomes more and more difficult to obtain a uniform light distribution in proportion to it. It has become to.

Also proposed is a method of irradiating the entire surface to be irradiated by dividing the surface to be irradiated into a plurality of fields using a light source having a cylindrical light beam and scanning the light source along a predetermined track. However, it is not sufficient in terms of uniformity of light distribution.

The present invention has been made in view of the above problems, and an object thereof is to provide an exposure light source device having a uniform light distribution.

[0010]

In order to solve the above-mentioned problems, according to the present invention, an original plate on which a shadow mask pattern is formed and a dry plate having an unexposed photosensitive film are vacuum-contacted and irradiated with light. An exposure light source device used in a pattern forming step of forming an inversion pattern by: including an exposure light source portion longer than one side of the pattern, and a driving device that reciprocates the exposure light source in the other direction of the pattern, The exposure light source device is characterized in that a lens unit having a large number of converging optical fibers arranged is disposed on the light exit side of the exposure light source unit.

[0011]

A lens unit in which a large number of converging optical fibers are arranged on the light outlet side of the exposure light source by using the exposure light source of the exposure light source device as a substantially linear light source longer than one side of the mask pattern surface. By arranging, the light distribution on the irradiation surface becomes uniform regardless of the irradiation area. This is because the converging optical fiber has a uniform distribution of the light illuminance in its cross section. By using a substantially linear light source longer than one side of the mask pattern surface, By making the distribution of light illuminance uniform and further moving the exposure light source in the other direction, a uniform light distribution can be obtained on the entire irradiation surface.

Therefore, it is possible to provide an appropriate light intensity, and it is possible to produce a printing plate in which the pattern dimension variation is extremely small, the pattern is well cut, and pinholes are not generated.

Further, since the exposure light source can be used in the vicinity of the irradiation surface, the space for placing the exposure light source device and the reversing device for vacuum-contacting the original plate and the dry plate can be small.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the outline of the present invention. An original plate 11 having an opaque pattern at a portion corresponding to a shadow mask hole forming portion and a raw dry plate 12 on which an unexposed photosensitive film is adhered are vacuum-contacted, and an exposure light source 20 is moved upward by a drive device 21.
u, move to Yd downward. The scanning speed of the exposure light source 20 can be changed by the changeover switch 22.

FIG. 2 shows the exposure light source 20 and the driving device 21 of FIG.
FIG. 1 is a schematic overall view of an exposure light source device provided with. Figure 2 (a)
Is a schematic perspective view, (b) is a plan view, and (c) is a side view. In FIG. 2, neither the original plate having an opaque pattern at the portion corresponding to the shadow mask hole forming portion nor the raw dry plate coated with the unexposed photosensitive film is shown, but only the exposure light source device is shown. The exposure light source 20 is moved up and down by a drive device 21 including a drive chain connected to a speed change motor along a guide rod 23 in order to prevent blurring during movement. At the time of movement, the exposure amount fluctuates if the vertical movement speed is different, so a balancer (not shown) is attached to the back surface so that the vertical movement speed is constant. Exposure light source 20
The upper and lower moving ranges can be arbitrarily changed by changing the positions of the limit switches mounted above and below the guide rod 23 of the exposure light source device according to the size of the material to be exposed. The scanning speed of the exposure light source 20 is specified by turning the drive motor rotation speed control knob mounted on the control panel 24, and the number of reciprocations is specified by the counter mounted on the control panel 24. The signal of the limit switch is transmitted to the changeover switch 22 and the operating state of the drive device 21 is controlled so that it can be arbitrarily changed. Further, since the caster 25 is attached to the lower part of the exposure light source device, it is possible to manually bring the original plate and the raw dry plate into close contact with each other by manual force.

Details of the structure of the exposure light source are shown in FIG. Figure 3
3A is a side sectional view, and FIG. 3B is a plan sectional view. As the light source, a long and narrow incandescent fluorescent lamp 31 of 40 W is used as a lamp, and a shutter 32 and a lens unit 40 in which a large number of converging optical fibers are arranged are arranged on the light output side. As the structure of the shutter 32, for example, there is one in which a spring coil is arranged around a movable iron core. When the electric current is applied, the coil is contracted and the iron core is rotated to move the shutter. You can At this time, the axis of the converging optical fiber that constitutes the lens unit 40 is oriented substantially in the central axis direction of the fluorescent lamp 31. When the shutter 32 falls down, the light emitted from the incandescent fluorescent lamp 31 passes through the lens unit 40 and goes out of the exposure light source. The lens unit 40 made of this converging optical fiber makes the light distribution uniform in the width direction of the mask pattern. The operation of the lens unit 40 will be described below. The converging optical fiber is characterized by its refractive index distribution as compared with the clad type optical fiber. That is, since the clad type optical fiber utilizes total reflection at the interface, it has a discontinuous refractive index distribution composed of a high refractive index core and a lower refractive index, but the converging optical fiber is The refractive index continuously decreases from the central axis toward the outer side in the radial direction. Further, in general, the speed of the light traveling in the medium decreases as the refractive index increases, so that the converging optical fiber can make the light illuminance distribution in the cross section uniform. Therefore, since the converging optical fibers serve as one light source and are densely arranged, even if the light distribution of the light source itself is nonuniform, the variations are averaged. As a result, a surface light source having a desired width and length and a uniform light distribution can be formed.

The diameter of one converging optical fiber constituting the lens unit 40 is about 0.5 to 1.0 mm, and the image forming range thereof is about several mm. By arranging a large number of light converging optical fibers that overlap each other and form an erecting equal-magnification image, a surface light source in a required range can be obtained.

FIG. 4 is a partially cutaway enlarged view of the lens unit 40 made of the converging optical fiber shown in FIG. 3, in which one made of the converging optical fibers 41 arranged in a zigzag pattern is used as one of the lens elements. It is a unit. FIG. 5 shows an arrangement in which the units shown in FIG. 4 are arranged in upper and lower two rows and provided at the light irradiation outlet of the exposure light source.

Further, in order to block light from other than the lens unit, black blinds of an automatic winding type may be attached above and below the exposure light source for unwinding and winding according to the movement of the light source.

Although only one exposure light source is attached to the exposure light source device in FIG. 2, the present invention is not limited to this. That is, the photosensitivity greatly varies depending on the type of emulsion of the photosensitizer used. For example, the sensitivity of a Kodak high resolution plate (HRP) is as low as about one-hundredth of that of a line precision plate (LPP), and exposure in this case slows down the scanning speed of the exposure light source and increases the number of scanning times. Although there is a means to increase the exposure amount, the exposure time becomes long and the work efficiency deteriorates. Therefore, the number of exposure light sources is not limited to one, and it is possible to arrange a plurality of exposure light sources and change the number of scanning times according to the emulsion sensitivity.

Further, depending on the emulsion, if the light intensity is too weak, the pinhole phenomenon is likely to occur even if the exposure amount is increased, and conversely, if the light intensity is too strong, the fog phenomenon occurs. Therefore,
It is necessary to arbitrarily select the type of light source used.

Furthermore, it is desirable that the distance between the exposed material and the lens unit is set to a distance for obtaining a constant light intensity determined by the sensitivity of the photosensitizer.

A pattern of a shadow mask used for a 35 V color picture tube, that is, a pattern of 770 mm × 600 mm is printed on a 30 inch × 43 inch Kodak LPP dry plate, and this embodiment and 200 are applied to the dispersion of the size.
Table 1 shows a comparison with a conventional device using a W mercury lamp.

[0025]

[Table 1] In Table 1, the exposure conditions of the examples are as follows: the distance between the exposure light source and the pattern is 800 mm, the scanning speed of the light source is 6 m / min, the scanning range is 1000 mm up and down, the number of scans is 1 reciprocation, and the exposure time of the pattern part is 15 mm. Second, the total exposure time including the part other than the pattern part is set to 20 seconds. The exposure conditions of the conventional example are as follows: a 200 W mercury lamp is used as the light source, the distance between the light source and the pattern is 2000 mm, the aperture diameter is 45 φ,
The illuminance is 2 lx and the exposure time is 10 seconds.

FIG. 5 shows another embodiment of the exposure light source.
5A is a side sectional view, and FIG. 5B is a plan sectional view.
As a light source, 100 W ball bulbs 51 are arranged in series in a number of lamps in the required width of the material to be exposed, and a heat absorbing glass plate 52 on the light exit side and a diffusion plate 53 for eliminating the image of the bulb and making the light distribution uniform. Is installed. Further, there is a solenoid-operated shutter 54, and when the shutter 54 is tilted, light passes through a lens unit 60 attached to one, which corresponds to substantially the center of the ball bulb 51, and goes out. The light intensity can be arbitrarily changed by changing the supply voltage of the ball bulb 51 via the sliding transformer.

As described above, according to the present invention, the distance between the exposure light source and the material to be exposed can be reduced, and the light source can be selected in a wider range. At this time, the wavelength of the lamp of the exposure light source must be adjusted to the photosensitive wavelength because the photosensitive wavelength varies depending on the photosensitizer applied to the raw dry plate which is the exposed material. Further, it is desirable to select the transmission wavelength of the light converging optical fiber so that the light converging optical fiber transmits light having a photosensitive wavelength.

Further, since the exposure light source can be used in the vicinity of the irradiation surface, the space for placing the exposure light source device and the reversing device for vacuum-contacting the original plate and the dry plate can be small.

Further, in the above-mentioned embodiment, the driving device is constituted by the driving chain and the exposure light source is moved up and down.
The present invention is not limited to this. That is, the drive device may have any structure as long as it can move the exposure light source back and forth, and the exposure light source may be vertically long and moved horizontally.

Furthermore, although the exposure light source device of the present application has been described with respect to the production of a shadow mask for a color picture tube, it can be used in other than the shadow mask production process.

[0031]

As described above, according to the present invention, the exposure light source of the exposure light source device is provided with respect to the surface of the mask pattern.
As a substantially linear light source longer than the side, by arranging a lens unit consisting of a large number of converging optical fibers arranged on the light exit side of the exposure light source, the light distribution on the irradiation surface can be distributed regardless of the irradiation area. Be uniform. Further, by moving the exposure light source in the other direction, a uniform light distribution can be obtained over the entire irradiation surface.

Therefore, it becomes possible to provide an appropriate light intensity, and it is possible to produce a printing plate in which the variation in the pattern dimension is extremely small, the pattern is well cut, and pinholes are not generated.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an outline of the present invention.

FIG. 2 is a schematic perspective view, a plan view and a side view showing an embodiment of the present invention.

3A and 3B are a side sectional view and a plan sectional view showing the structure of the exposure light source shown in FIG.

FIG. 4 is a partially cutaway enlarged view showing the structure of a lens unit in which a large number of converging optical fibers shown in FIG. 3 are arranged.

5 is a front view showing an exposure light source provided with the lens unit shown in FIG.

6A and 6B are a side sectional view and a plan sectional view showing another structure of the exposure light source.

FIG. 7 is a sectional view showing a structure of a conventional exposure light source.

[Explanation of symbols]

 11 ... Original plate 12 ... Raw dry plate 20, 40, 60 ... Lens unit 21 ... Driving device 31 ... Incandescent fluorescent lamp 51 ... Ball bulb 41 ... Focusing optical fiber

Claims (1)

[Claims] 1. An exposure light source device used in a mask pattern forming step of forming a reversal pattern by vacuum-contacting an original plate on which a shadow mask pattern is formed and a raw dry plate having an unexposed photosensitive film, and irradiating with light. In the above, an exposure light source longer than one side of the pattern and a driving device that reciprocates the exposure light source in the other direction of the pattern are provided, and a large number of converging optical fibers are arranged on the light outlet side of the exposure light source. An exposure light source device characterized in that a lens unit comprising the above is provided.