JPH03241634A - Manufacture of fluorescent screen for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To form dots with a shape near a true circle at all portions on a fluorescent screen by rotating a linear light source covered by a shielding plate having slits around the preset axis at a preset radius, and weighing the required exposure. CONSTITUTION:Phosphor dots are formed on a panel 1 by the exposure of a linear light source 3. The linear light source 3 is rotated at a preset radius centering a straight line 2a parallel with the tangential plane of the panel 1 through the exposure center 2. The linear light source 3 is covered by a shielding plate 5 having slits 4 with the preset width in the longitudinal direction centering the light source center 3a. The rotating radius is changed continuously or in steps as desired during rotation and finally set to zero. The slit width is inversely proportional to the rotating radius. The exposure time is inversely proportional to the rotating radius. The light source luminance is inversely proportional to the rotating radius. The light source 3 can be referred as equivalent to a light source apparently approximate to a sphere.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a color cathode ray tube phosphor surface of a shadow mask type dot-type phosphor using photolithographic technology, and in particular, the present invention relates to a method for manufacturing a phosphor surface of a color cathode ray tube using a shadow mask type dot-type phosphor, and in particular, the present invention relates to a method of manufacturing a phosphor surface of a color cathode ray tube using a shadow mask type dot-type phosphor. This invention relates to a method for manufacturing a fluorescent surface of a color cathode ray tube, which allows a dot shape close to a perfect circle to be obtained over the entire surface.

[Prior Art] Generally used color picture tubes for television use have a fluorescent surface in which a large number of narrow longitudinal stripe patterns of three primary color phosphors are repeatedly arranged in parallel in a predetermined color order. However, display terminals for data processing devices that require high-definition display use an array of small-diameter, generally circular dot patterns.

The fluorescent surface of the above color cathode ray tube for display terminals is coated with a black non-reflective layer (black matrix) in which holes are formed at positions corresponding to the phosphor driver 1 pattern to improve contrast, and these holes are filled. A three-primary color phosphor dot pattern is formed, and in each case, the light rays are emitted from a light source placed at a predetermined (substantially) n-light center and passed through a hole in the shadow mask, and the photoresist film or photosensitive material at the exposure position is exposed. It is manufactured using the well-known Holingraph technology, in which a phosphor film mixed with a fluorescent substance is exposed to light and solidified. In this process,
Previously, a point light source was used, which was a combination of a small ultra-high-pressure mercury lamp and a halo, commonly known as a collimator.

When using this light source, there were no problems with dot shapes, etc., but because the light intensity was low and the exposure time was long, it was necessary to use a linear light source, which was actually longer than the previous one. A method has come to be used in which light from a relatively long section of a high-pressure mercury lamp is used directly as an exposure light source without passing through a so-called collimator to obtain a large amount of luminous flux. However, when such a long and thin light source is used while stationary, there are various problems such as the desired circular shape becoming oval, and the shape and size varying depending on the position on the fluorescent surface. Therefore, many countermeasure proposals have been made, some of which are listed below.

Japanese Utility Model Publication No. 54-22375 describes a relatively long ultra-high pressure mercury lamp (actually, it is used by covering it with a shielding plate that extracts only the light from the central part of the arc, which is a stable light emitting part). It is shown that the entire housed lamp house can be rotated. There is no problem at the center of the fluorescent blood, but at the periphery, the dot shape is no longer a perfect circle because the light rays that passed through the circular hole in the shadow mask are projected diagonally onto the panel.
Furthermore, the exposure intensity changes gradually at the periphery of the dot, resulting in areas with poor sharpness during development.

Japanese Utility Model Application Publication No. 62-34.743 discloses rotating the light source and the fluorescent surface while changing the distance therebetween.

JP-A-61-99245 and JP-A-62-281230
The publication discloses moving or reciprocating an ultra-high pressure mercury lamp covered with a light-shielding plate containing Surin l- in a direction perpendicular to its tube axis.

[Problems to be Solved by the Invention] 3. The above-mentioned conventional techniques have certain effects at specific positions on the periphery of the fluorescent surface, which each proposal aims to improve; It is not possible to obtain a dot with a shape close to a perfect circle of the same size as the part.

The present invention controls the position, moving speed, size, brightness, etc. of the light source so that it becomes a substantially spherical light source, and creates a perfect circle not only in the center of the fluorescent surface but also anywhere on the periphery. An object of the present invention is to provide a method for manufacturing a fluorescent surface of a color cathode ray tube, which allows dots of similar size and shape to be obtained.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a linear light source (forming a fluorescent surface) covered with a plate having a desired width of 1 to 100 mm perpendicular to the longitudinal direction of the light source. (parallel to a tangential plane touching the panel at the center of the panel) was exposed while rotating at a desired radius around a straight line passing through the exposure center and parallel to the light source as the central axis. More specifically, a) the length of the radius during the rotation is changed continuously or stepwise as desired;

b) The slit width is adjusted continuously or stepwise as desired in conjunction with changes in the radius, so that the slit width is narrow when the radius is long, and becomes wide when the radius is short or the light source passes through the exposure center. C) Control the speed of radius change continuously or stepwise so that the exposure time is short when the radius is long and the exposure time is long when the radius is short or the light source passes through the exposure center. d) Adjust the light source brightness continuously or stepwise in conjunction with changes in the radius so that the light source brightness is low when the radius is long, and high when the radius is short or the light source passes through the exposure center. to change, to make.

[Action] If the light source exists only on one plane (even if it is rotated or translated in parallel), the shape of the exposed area formed on the inner surface of the panel by the light rays passing through the nearly perfect circular hole of the shadow mask will be If it is generally circular or square, it will be a substantially perfect circle at the center of the panel where the light rays intersect perpendicularly to the shadow mask surface, but it will not be circular at the periphery of the panel where the light rays obliquely intersect the shadow mask surface. If the linear light source is rotated and the axis of rotation is moved up and down, the shape approaches a circle, but the illuminance of the exposed area and the degree of chemical change in the photosensitive material become uneven, making it impossible to obtain a neat circular dot after development. Sometimes.

The point light source used previously required a long exposure time due to insufficient light intensity, but there were almost no problems with the shape of the dots. The present invention rotates a linear and somewhat long light source around a straight line that passes through the center of exposure and is parallel to the panel surface that is the exposure target (strictly speaking, parallel to the tangential plane that is in contact with the panel surface at the center of the panel). Change the radius appropriately (by controlling the speed of radius change (stopping time for each stage when changing stepwise)), and if necessary, change the slit width of the light shielding plate covering the light source or the light source brightness to change the radius. By changing the brightness in conjunction with the change in , a substantially spherical light source (expanding a point into a sphere) is realized, with the brightness being highest near the center and gradually decreasing in brightness at the periphery. With such a light source, substantially circular dots can be obtained anywhere on the panel surface. In practice, the speed of change in radius, slit width, light source brightness, etc. are controlled in combination so that circular dots can be obtained over a wide range on the fluorescent surface. The chemical change in the photosensitive material film occurs in response to the amount of exposure of the exposed area, that is, the time-integrated value of the illuminance, so it is in this sense that the light source is referred to as a spherical light source.

[Example] The present invention will be explained with reference to FIG. 1(a). In the figure, 1 is a panel with a photosensitive film formed on one back side, 2 is the exposure center, 2a is a straight line passing through the exposure center and serves as the central axis of rotation, and 3 is a line parallel to the tangential plane touching the panel at the center of the panel. The arranged linear light source (ultra-high pressure mercury lamp) 3a is the center of the light source. The distance between the straight line 2a and the light source 3, that is, the radius of rotation, is 1 to 2I.
It is approximately IIn (S/4 to S/2, where S is the distance between adjacent primary color exposure centers). FIG. 1(b) is a detailed view of the light source section, in which the linear light source 3 is covered by a light shielding plate 5 having slits 4 formed symmetrically on both sides of the light source center 3a and perpendicular to the light source.

At the start of exposure, the linear light source 3 is rotated about the straight line 2a, and as the exposure progresses, the radius of rotation is decreased, and at the end of the exposure, the light source 3 is aligned with the straight line 2a. At this time, by reducing the radius of rotation at a speed as shown in FIG. 2(a), the exposure time becomes longer as the light source 3 approaches the straight line 2a, which is the central axis of rotation. Furthermore, as the light source 3 approaches the straight line 2a, which is the central axis of rotation, the light source brightness is increased as shown in FIG. 2(b), or the slit width is widened as shown in FIG. 2(c). , the exposure amount may be increased near the straight line 2a at the center of rotation. By optimizing the weighting of the exposure amount in this way, it becomes equivalent to performing exposure with a light source that is approximately spherical in appearance. The roundness of the risk hole shape and the phosphor dot shape can be improved, and effects such as improved color purity tolerance and geomagnetic tolerance can be obtained.

[Effect of the invention] As explained above, according to the present invention, the product characteristics are 1.
The color linearity latitude and geomagnetic latitude are each improved by about 10 μm, the state of film breakage around the black matrix holes and phosphor dots is improved, and the level of color unevenness is also improved. on the other hand,
In terms of production, since the slit width can be selected wider than in conventional methods, the illuminance can be improved even if the light source brightness remains the same, so the exposure time can be cut in half and throughput improved.

[Brief explanation of drawings]

FIG. 1(a) is an explanatory diagram of the present invention, FIG. 1(b) is a detailed view of the light source according to the present invention, and FIG. 2(, ) is a state in which the radius of rotation of the light source decreases as the exposure time passes. Figure 2 (
b) is a diagram showing a state in which the light source brightness increases as the exposure time elapses; FIG. 2(c) is a diagram showing a state in which the slit width of the light source shielding plate becomes wider as the exposure time elapses. 1... Panel, 2... Exposure center, 2a... Straight line passing through the exposure center and serving as the central axis of rotation, 3... Linear light source, 3a... Light source center, 4... Slit, 5
Figure 1 (0) (b) 4-. 7 So・Zo 1 5-Cave wo Saka Diagram (b) 188-

Claims (1)

[Claims] 1. In a method for manufacturing a fluorescent surface of a shadow mask type color cathode ray tube, in which a fluorescent surface on which phosphor dots of different emission colors are arranged is formed by photolithography, A color cathode ray tube characterized in that a linear light source covered with a plate having orthogonal slits of a desired width is exposed while being rotated at a desired radius with the central axis being a straight line passing through the exposure center and parallel to the light source. A method for manufacturing a fluorescent surface. 2. The method for manufacturing a fluorescent surface of a color cathode ray tube according to claim 1, wherein the rotation is performed while changing the length of the radius continuously or stepwise. 3. The slit width is changed continuously or stepwise in conjunction with the change in radius so that when the radius is long, the slit width is narrow, and when the radius is short or the light source passes through the exposure center, the slit width is wide. 3. A method for manufacturing a fluorescent surface of a color cathode ray tube according to claim 2.