JP2003217471A - Color cathode-ray tube and color display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cathode-ray tube and a color display device having better image quality as compared with conventional ones by forming a phosphor dot pattern having high accuracy in shape and position on a face panel of a high-precision color cathode-ray tube or a display device. <P>SOLUTION: An integrally machined mold die is used to form a correction lens composed of a plurality of fine planes or curved surfaces, and constituted so as to be uniform, over the whole surface, in line width and contrast of lattice dark and light lines generated by stepped parts between the adjacent fine planes and curved surfaces when subjected to irradiation of exposure light. A photosensitive film on the internal surface of the face panel of the cathode-ray tube is exposed while the correction lens is swung. Thereby, since the whole surface of the photosensitive film on the internal surface of the face panel of he cathode-ray tube is uniformly exposed, the phosphor dot pattern having high accuracy in shape and position is formed, so that this cathode-ray tube and this color cathode-ray tube device having good image quality can be provided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube and a color display device, and more particularly to a correction lens for forming a cathode ray tube fluorescent screen dot pattern used in an exposure process for forming a fluorescent film of the color cathode ray tube (hereinafter referred to as a correction lens). The present invention relates to a high-definition / high-quality cathode ray tube and a color display device capable of obtaining a high-definition and high-quality cathode ray tube by improving (1).

[0002]

2. Description of the Related Art With the demand for higher definition of color cathode ray tubes, the precision required for the exposure process for forming the fluorescent surface by exposure and development is also increasing.

In forming the fluorescent surface of a black matrix type color cathode ray tube, a black body is formed leaving a large number of stripe-shaped or dot-shaped holes, and stripe-shaped or dot-shaped fluorescent films are formed in the holes. .
Therefore, the positions of the hole and the phosphor film coincide with each other, but it is important to accurately position them at the electron beam projection position.

Various correction lenses are used to perform the above-mentioned alignment (registration correction), but some have a continuous curved surface and some have a discontinuous curved surface, both of which refract light rays for exposure. Since it is intended to approximate the actual electron beam trajectory, it has a very complicated surface shape.

In the color cathode-ray tube having the stripe-shaped fluorescent film, the fluorescent film has a long belt shape in the vertical direction, and therefore, even if the electron beam projected for emitting the light is displaced in the vertical direction. Does not cause color shift. Therefore, since only the beam deviation in the horizontal direction needs to be corrected, the degree of freedom in designing the correction lens is high. However, since the fluorescent surface cannot be arranged at a high density, high resolution cannot be obtained. For this reason, a dot-shaped fluorescent film is formed in a color cathode ray tube for computer terminals which requires high resolution.

When forming the fluorescent film of the color CRT having the dot-shaped fluorescent film, horizontal and vertical corrections must be performed at the same time, so that various correction lenses can be obtained to obtain the optimum correction amount. Is used.

For example, an exposure table incorporating a discontinuity correcting lens as disclosed in Japanese Patent Publication No. 47-40983 will be described with reference to the drawings.

FIG. 8 shows the structure of the exposure table.
A face panel 85 having a shadow mask 87 mounted thereon is installed on an exposure table 84 having a light source 81, a lens 82, and a correction lens 83 built therein. The correction lens 83 is shown in FIG.
To (c) the plane shape and the horizontal direction (x),
It has a sectional shape having an inclination in the vertical direction (y) and is divided into a plurality of square or rectangular blocks in each direction. The exposure light beam emitted from the light source 81 is the lens 8
After passing through 2, the light is refracted by the correction lens 83, reaches the inner surface of the face panel 85 through the aperture of the shadow mask 87, and exposes the photosensitive film 86. However, the discontinuous boundary surface 83 ′ of the correction lens 83 has a lattice shape. The dark line pattern is the photosensitive film 8
In order to prevent exposure to No. 6, the correction lens 83 is swung in the x and y2 directions during the exposure process. However, due to the influence of this grid-like dark line pattern, the dot formation cannot be made highly accurate, so various methods have been tried for suppressing the occurrence of various grid-like dark line patterns. For example, the correction lens disclosed in Japanese Patent Laid-Open No. 62-154525 is one example. This lens shape will be described.

FIG. 10 is a sectional view of a correction lens for suppressing the grid-like dark line pattern to some extent. The effective surface of the correction lens is divided into a plurality of regions, the central thickness of the region 103a is d1, the central thickness of 103b is d2, the central thickness of 103c is d3, the central thickness of 103d is d4, Assuming that the central thickness of 103e is d5 and the central thickness of 103f is d6, these d1, d2, d3, d4, d5 and d6 are the step portions 104a, 104b, 104c, 104d and 104e between the respective regions.
It was about 00 μm. By reducing the size of each step in this way, the contrast and area of the grid-like dark line pattern (dark line stripes) on the phosphor screen are reduced.

However, even if the above-mentioned correction lens is used, the need for high definition of the color CRT cannot be satisfied.

FIG. 11 is a partially enlarged sectional view of a conventional correction lens (the thickness of the center of each region is ignored). Area boundaries 34a and 34b of the conventional correction lens 33
Is perpendicular to the reference plane 32. Therefore,
As shown in FIG. 3A, since the incident light emitted from the light source and obliquely incident on the area boundary portions 34a and 34b of the correction lens 33 is secondarily refracted, the light is partially concentrated or dispersed. As a result, the light amount of the emitted light changes, and a dark line having a width t corresponding to the height of the step of the region boundary portion is generated.

FIG. 12 is a perspective view of a conventional correction lens mold used to mold the correction lens. The correction lens mold 121 has a plurality of desired divided regions (for example, 123) of the correction lens to be molded, and each region has a region boundary portion (for example, 124). The mold according to the prior art is one mold by combining several hundred blocks corresponding to the above regions. It is a so-called assembly type. Therefore, it is very difficult to further reduce the area of each region divided into a plurality of correction lenses or further reduce the step of the region boundary portion in order to satisfy the demand for high definition. There is.

When the light ray emitted from the light source is passed through the correction lens formed by the mold 121 to expose the photosensitive film on the inner surface of the face panel of the color cathode ray tube, as shown in FIG.
As described with reference to (a), a grid-like dark line pattern having a non-uniform width is generated due to the step heights of different areas of the correction lens surface on the photosensitive film, and the dots on the fluorescent screen of the color cathode-ray tube vary. To do. That is, the amount of light reaching the photosensitive film becomes uneven, the shape accuracy of the phosphor dots is poor, and the position accuracy is also poor. For this reason, it is difficult to obtain a high-definition color CRT with good image quality.

[0014]

In the above prior art, due to the step at the boundary between different areas of the correction lens surface, the exposure light that passes through the correction lens and is applied to the shadow mask has a width and a contrast that are different from each other. A uniform grid-like bright and dark line pattern is generated. Then, as a means for alleviating the effect of the grid-like bright and dark line pattern, the thickness of the center of the lens plane is adjusted to reduce the occurrence of the grid-like bright and dark line pattern, or at the time of exposure. By swinging the correction lens, the influence of the grid-like bright and dark line pattern is made to appear uniformly over the front surface of the exposure surface. However, the screen, which was conventionally composed of 400,000 pixels, is composed of more than 1 million pixels. We have not been able to fully meet the needs for high definition color CRTs.

As described above, this is a CD with good image quality.
In order to obtain T, highly accurate phosphor dot position accuracy is required, and in order to obtain highly accurate phosphor dot position accuracy, it is necessary to form highly accurate dots. This is because a highly accurate correction lens for satisfying it could not be obtained.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and eliminate the influence of the grid-like bright and dark line pattern generated by the correction lens at the time of exposure. An object of the present invention is to provide a high-definition and high-quality cathode ray tube and color cathode ray tube device whose position is formed with high precision.

[0017]

Means for Solving the Problems The above-mentioned object is to make the width and contrast of a grid-like bright and dark line or dark line pattern generated by a correction lens in which an incident surface of exposure light is composed of a plurality of flat surfaces or curved surfaces having different inclinations, This is achieved by forming a correction lens so that it is uniform over the entire exposure surface, and exposing while swinging the correction lens.

In the correction lens, a plurality of flat surfaces or curved surfaces having different inclinations formed on the lens surface are miniaturized to half to ⅓ or less of the conventional size, and each of the miniaturized flat surfaces or curved surfaces is reduced. It is formed so that the respective flat surfaces or curved surfaces are positioned so that the step generated at the boundary is as small as possible, and (1) the inclination of the step surface at the boundary is made parallel to the incident direction of the exposure light, or
(2) The inclination of the step surface of the boundary portion is 120 degrees or less with respect to the reference surface, and is made constant with respect to the incident direction of the exposure light.
Alternatively, (3) the inclination of the step surface of the boundary portion is set to 120 degrees or less with respect to the reference surface to form minute unevenness on the surface of the step surface, or (4) the inclination of the step surface of the boundary portion is used as the reference. The angle is 120 degrees or less with respect to the surface, and streaks or scratches are formed with a constant width at the portion where the grid-like dark line is emitted on the side of the exit surface of the exposure light of the correction lens to roughen the surface, or these (1 ) To (4) are combined.

When the correction lens irradiates the shadow mask while swinging the correction lens by making the width and contrast of the grid-like bright and dark line or dark line pattern generated by the correction lens uniform over the entire exposure surface. The amount of light applied to the exposure surface within a constant exposure time becomes uniform over the entire area of the exposure surface. By making the exposure amount uniform in this way, a dot pattern of a fluorescent film having good position accuracy and shape accuracy is formed on the face panel of the cathode ray tube.

Here, the width and contrast of the grid-like bright and dark line or dark line pattern generated by the correction lens will be explained according to the order described in the section of the means for solving the above problems. By forming the surface parallel to the incident direction of the exposure light, the proportion of the second refraction on the step surface by the exposure light is reduced, and the area that affects the exit surface is reduced. As a result, the line width due to the exposure light that has passed through the correction lens is narrow, and the contrast is constant,
A grid-like bright and dark line pattern is generated. (2) By making the inclination of the step surface of the boundary portion 120 degrees or less with respect to the reference surface and a constant inclination with respect to the incident direction of the exposure light, the exposure light incident on the step surface and its vicinity interferes. Then, the light quantity of the exposure light emitted from the part affected by the step surface of the correction lens is reduced and dispersed in a relatively wide area, and this part creates a grid-like dark line pattern with uniform width and contrast. To do. (3) By setting the inclination of the step surface at the boundary to be 120 degrees or less with respect to the reference surface and forming minute irregularities on the surface of the step surface, the light transmittance at the step surface is reduced, and correction is performed. The light amount of the exposure light emitted from the portion affected by the step surface of the lens is further reduced as compared with the case of the above (2), and this portion generates a grid-like dark line pattern having a uniform width and contrast. . (4) The inclination of the step surface at the boundary is set to 120 degrees or less with respect to the reference surface, and lines or scratches having a constant width are formed at a portion where a dark line in a grid pattern is emitted on the side of the exit surface of the exposure light of the correction lens By roughening the surface by forming a pattern, a dark line pattern in a grid pattern having a uniform width and contrast is generated by this portion.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

Example 1. FIG. 1 is a perspective view showing the outer appearance of a correction lens according to an embodiment of the present invention. FIG. 2 is a sectional view of the correction lens.

The material forming the correction lens 3 is an optical plastic such as polymethylmethacrylate having a high light transmittance, and a plurality of flat surfaces or curved surfaces having different inclinations in the x and y directions with respect to the reference plane 2. 3a form a set.

The correction lens according to the present invention shown in FIG.
Although it has a shape similar to that of the correction lens manufactured by the conventional technique as shown in FIG. 9, in order to mold these correction lenses, conventionally, an assembly-type mold is used for each one. In contrast to the case where the respective planes or curved surfaces are formed by the mold, in the present invention, the respective planes or curved surfaces are formed by using an integral mold in which one mold material surface is formed by machining.

As described above, since the correction lens is molded by using an integral mold, a plurality of flat surfaces having different inclinations on the correction lens 3 or the minimum length of each side of the curved surface 3a is conventionally used. Since it is not restricted by the assembling type die, the dimension of each side of the flat surface or the curved surface 3a is half to one as compared with the dimension of each side formed by the conventional assembling type die. It can be formed by miniaturizing to / 3 or less.

Further, the above-mentioned integral type is arranged so that each plane or curved surface is positioned so that the value of the largest step among the steps at the boundary portion of the plane or curved surface having these inclination angles becomes the smallest (minimum). By determining the processing conditions, it is 100 in the conventional correction lens that is molded using the assembly type mold.
It is possible to reduce the level difference at the boundary portion, which was around μm, to 5 μm or less.

Further, since the integral mold for molding the above-mentioned correction lens is formed by machining by the method described later, in the present invention, the lens surface boundary step 4a is formed in the lattice shape formed by the step 4a. It can be formed at various angles according to the degree of occurrence of the bright and dark lines.

As a result, the step of the discontinuous boundary portion, which greatly affects the exposure effect for dot formation, can be greatly reduced, and the effect of the boundary step 4a on the area of the effective surface of the lens surface 3a is small, which is effective. The area is increased, and the degree of freedom in design can be increased.

FIG. 3 is a partially enlarged cross-sectional view of the conventional correction lens and the correction lens of the present invention and a comparison diagram of the exposure effect.

The step 3 of the boundary surface of the lens surface of the conventional correction lens
4a is configured to be perpendicular to the reference surface 32, and since the incident angle of the exposure light incident on the lens surface boundary step 34a differs depending on the location, it obliquely enters the lens surface boundary step 34a. The light quantity and the width of the grid-like bright and dark line pattern of the emitted light generated by the partial concentration or dispersion of the light due to the secondary refraction of the incident light causes a change (distribution) depending on the location.

On the other hand, in the correction lens of the present invention, the lens surface boundary step 4a is formed to be smaller than 1/20 of that of the conventional correction lens, so that the exposure light transmitted through the correction lens of the present invention is exposed. The amount of light and the width of the grid-like bright and dark lines generated by the light can be made substantially uniform over the entire exposed surface.

Further, the correction lens according to the present invention shown in FIG. 3B is formed so that the inclination direction of the lens surface boundary step shape 4a is parallel to the incident direction of the exposure light incident on the correction lens. Indicate the case.

As described above, the lens surface boundary step shape 4a
Since the inclination direction of the incident light is formed to be parallel to the incident direction of the exposure light incident on the correction lens, the proportion of the incident light that is secondarily refracted on the step surface is reduced, and thus the grating generated by the second refraction is generated. It is possible to reduce the amount of light of the bright and dark lines substantially uniformly over the entire exposed surface, and to narrow the width of the bright and dark lines almost uniformly over the entire exposed surface.

Next, a mold for molding the correction lens of the present invention shown in FIG. 1 will be described.

FIG. 13 is a perspective view showing the outer appearance of a mold used for molding the correction lens according to the embodiment of the present invention shown in FIG. As a material of the die 131, a non-ferrous soft metal such as an aluminum alloy, brass, or copper is suitable from the viewpoint of workability.

The surface of the die 131 is formed corresponding to the transfer surface of the correction lens shown in FIG.

Next, a method of processing this die will be described. FIG. 14 is a view showing a cutting device for a correction lens forming die of the present invention. FIG. 15 is a view showing a flow chart of the cutting process of the mold of the present invention.

The mold 131 is held on a positioning table 143 in the pitch direction on the Z table. On this mold surface, the transfer surface of the above-mentioned correction lens surface shape is cut using a cutting tool such as a diamond tool. The diamond bite 144 is rotatably held on the rotary table 142 with the center of the tip of the cutting edge as the center of rotation, and is cut by the movement of the table 141 in the Y direction with respect to the die 131, and the table 141 is moved in the x direction. The cutting feed is applied by continuously moving.

Before performing this cutting, the height of the step 4a at the discontinuous boundary is calculated in advance from the flat surface of the correction lens of the present invention or the inclination angle of the curved surface 3a, and the maximum value of the step is minimized. Correction lens 3 optimized to be (minimum)
Determine the shape of. Furthermore, the incident angle of the light incident from the light source is calculated and the contact point with the adjacent inclined surface is obtained by the trigonometric function, the maximum value of the step is minimized, and the inclination direction of the lens surface boundary side wall is the exposure from the light source. The processing conditions are determined so that they are parallel to the incident direction of the working light. This cycle is sequentially repeated to determine the machining positions at the steps of all discontinuous boundaries, and then the die cutting process is performed.

Depending on the position of this cutting feed, the Z table 143 is pitch-fed each time the cutting of one flat surface or curved surface 133 is completed, and the desired flat surface or curved surface 133 to be cut next in the desired y direction. The diamond table 144 is machined by changing the posture of the diamond cutting tool 144 to an inclined angle by the rotary table 142 during cutting. The length of the cutting edge of the diamond cutting tool 144 in the direction perpendicular to the cutting direction x may be substantially equal to the length of a desired flat surface or curved surface 133 in the cutting width direction.

Next, a method for forming the mold of the correction lens of the present invention by plastic working will be described.

FIG. 16 is a view showing a plastic working apparatus for a correction lens forming die of the present invention. The mold 164 is held on a positioning table 163 that is held by the x table and the y table so as to be movable in the two orthogonal axis directions. A punch 16 for forming a plurality of flat surfaces or curved surfaces 133 having different inclinations with respect to the reference bottom surface 132 on the mold surface.
5 is rotatably held by the goniometer stages 166 and 167 about the machined surface of the punch, and the goniometer stage is attached to the lower end of the z-axis 168 which is vertically movable. In addition, the pressing force of the punch 165 to the processing surface is controlled,
Control device 169 including a force sensor for managing
Also attached to the lower end of this z-axis 168. The z-axis 168 is held by the column 170.

Next, the processing process of the correction lens molding die using this apparatus will be described.

FIG. 17 is a view showing a flow chart of the plastic working process of the die of the present invention. Before performing the die machining, the height of the step 134 at the discontinuous boundary is calculated in advance from the plane to be machined or the inclination angle of the curved surface 133, and the machining position where the step is minimized is determined. When the light / dark line is easily generated, the incident angle of the incident light is calculated from the light source, the contact point with the adjacent inclined surface is calculated from the trigonometric function, the step is minimized, and the inclination direction of the lens surface boundary side wall is the light source. Determine the processing conditions that are parallel to. This cycle is sequentially repeated to determine the processing position on the steps of all discontinuous boundaries, and then the mold processing is performed.

As the material of the punch 165, a high hardness material such as diamond, CBN, or super hard is suitable, and the shape of the surface involved in the processing of the lower end portion is a desired flat surface or a transfer surface of the surface shape of the curved surface 133. To be processed.
The position of the punch 165 with respect to the die 164 matches the inclination in the x and y directions with respect to the reference bottom surface 132 required for the surface to be processed, and the goniometer 166 in the x direction, and y.
The gonio stage 167 in each direction is positioned by a drive source such as a pulse motor. Also, the punch and die 164
Relative positioning in the xy plane is performed by driving the x table and the y table.

After performing this relative positioning, the punch 16
5, the z-axis 168 holding 5 is pushed down to press the surface of the mold 164, and the control device 169 including a force sensor controls and manages the pressing force to obtain a desired flat surface or curved surface 133.
After the formation, the posture of the punch 165 is changed to form the step difference shape of the lens surface boundary portion. This cycle is sequentially repeated to process the mold.

The above processing method is a method of molding the mold of the correction lens of the present invention using a plastic processing method.

After finishing the processing of the mold by using either the plastic working method or the cutting method described above, an optical plastic such as polymethylmethacrylate having a high light transmittance as described above is formed on the surface of the mold. Alternatively, a correction lens is molded by supplying a thermosetting resin and heating and compression. In addition, by supplying UV curable resin to the mold surface,
The correction lens can also be formed by irradiating with ultraviolet rays.

In the mold manufactured by the two kinds of processing processes of the above-mentioned plastic working method and cutting processing method, the desired flat surface or curved surface 133 and the mold surface shape can be freely designed, so that a highly accurate correction lens is provided. Can be manufactured, and the pattern accuracy of the fluorescent film is improved, so that a high-definition CRT can be exposed.

The above-mentioned mold can be formed by electric discharge machining in addition to the above-mentioned plastic working method or cutting method.

Next, a method of exposing the photosensitive film on the inner surface of the face panel of the cathode ray tube by using the correction lens of the present invention formed by the above-described processing method to form the dot pattern of the phosphor will be described.

The method for forming the dot pattern of the fluorescent substance is the same as the method described with reference to FIG. 8 in the section of the prior art, and in the present invention, the conventional correction lens 83 in FIG. Replaced by the correction lens 3 by
The exposure light (shown by the dotted line in the figure) emitted from the lens 1
2 and the correction lens 3 are transmitted to illuminate the shadow mask 87. At this time, as the correction lens 3 is swung, the exposure light is uniformly irradiated on the shadow mask 87 within a predetermined time as described above. On the photosensitive film on the inner surface of the face panel, the light amount is uniformly distributed over the entire exposed surface.

By using the uniformly exposed photosensitive film as a mask to etch the fluorescent film formed under the layer of the photosensitive film, the inner surface of the face panel of the cathode ray tube has good positional accuracy and shape accuracy. A dot pattern of the fluorescent film is formed.

Further, by adopting the color cathode ray tube manufactured by the above method, a high-definition television set and a terminal monitor can be obtained.

Next, the result of evaluating the face panel of the cathode ray tube produced by the above method will be described.

FIG. 21 is a diagram comparing the exposure effects due to the difference of the correction lenses when the dot pattern of the fluorescent film is formed on the inner surface of the face panel of the cathode ray tube using the correction lens according to the present invention or the conventional correction lens. .

For comparison of the exposure effects, a television camera installed on the front side of the face panel 85 of a cathode ray tube on which a dot pattern of a fluorescent film is formed under each condition is uniformly illuminated on the inner surface 86 of the face panel from the back side. Then, the surface of the face panel was detected, and the detected image signal was processed in units of detection pixels.

The cathode ray tube face panel 85 manufactured by the above-described method generally has a longitudinal direction (y in FIG. 21).
In the image signal processing, in order to improve the processing accuracy, a signal obtained by adding up the signals of each pixel in the vertical direction is used in the horizontal direction (FIG. 21). The fluctuation of the luminance in the x direction) was evaluated.

Here, as an index for evaluating the fluctuation of the brightness, the brightness fluctuation as defined by the following equation (the brightness of each point in the x direction added in the y direction in the predetermined range 211 of the cathode ray tube fluorescent surface 210): Was differentiated by the coordinate x of each point) and the luminance variation rate.

Luminance fluctuation = d ² (luminance) / dx ²

[0060]

[Equation 1]

Here, the brightness variation defined above has a good correlation with the streak unevenness confirmed when the predetermined range 211 of the CRT fluorescent surface 210, which is the measurement surface, is visually observed. In order to obtain a high-quality cathode ray tube in which the unevenness of the stripes cannot be visually confirmed, it is necessary for the inventors to make it so that the luminance fluctuation is small and the luminance fluctuation rate is ± 0.15% or less. Experimentally required by.

In the present invention, the correction lens used for exposure is
The length of one side of a flat surface or curved surface constituting the lens surface is subdivided into half to one-third or less of that of the conventional one, and in addition, the energy of the light irradiated to the exposure surface at the time of forming the fluorescent screen pattern is partially varied. In order not to connect with each other, the step difference between multiple flat or curved surfaces with different inclinations is minimized with respect to the reference plane.
The boundary side wall is formed so that its inclination direction is parallel to the optical path of the light incident from the light source, and the exposure is performed while swinging this correction lens, whereby uniform exposure is realized over the entire exposure surface. By reducing the luminance variation rate to ± 0.05% or less compared to ± 0.35% of the conventional correction lens, the target luminance variation rate of ± 0.15% or less could be achieved. .

FIG. 21 shows a typical example according to the present invention. When a plurality of cathode ray tube face panels based on the above-mentioned embodiment were prepared and their luminance fluctuations were measured to obtain the luminance fluctuation rate. All of them were able to achieve the target luminance fluctuation rate of ± 0.15% or less.

That is, by reducing the width of the grid-like bright and dark line pattern that deteriorates the exposure effect, the accuracy of the pattern of the fluorescent film, that is, the positional accuracy and shape accuracy of the dot pattern is improved, and high definition is achieved. It can be seen that the color cathode ray tube was obtained. Example 2. FIG. 4 is a perspective view showing the outer appearance of a correction lens according to another embodiment of the present invention. FIG. 5 is a sectional view of a correction lens according to another embodiment of the present invention in FIG. Figure 6
The partial expanded sectional view of the conventional correction lens. FIG. 7 is a partially enlarged sectional view of a correction lens according to another embodiment of the present invention in FIG.

As a material for forming the correction lens 4, a plurality of planes made of optical plastic such as polymethylmethacrylate having a high light transmittance and having different inclinations in the x and y directions with respect to the reference plane 4c, Alternatively, it is formed of a set of curved surfaces 4b.

FIG. 4 has a shape similar to that of the correction lens manufactured by the conventional technique, but as shown in FIG. 7, a plurality of plane or curved area boundaries having different inclination angles of the correction lens are used. The angle .theta. Of the stepped surface 4a "of the portion with respect to the reference surface 4c is 120.degree. Generally, in consideration of releasability from a mold for molding a correction lens, a lens having such a shape cannot be molded, but in the present invention, the mold has a correction lens surface shape with a subdivided plane or curved surface. Since the transfer surface is formed, it is possible to reduce the height of the area boundary step of the area having a plurality of flat surfaces or curved surfaces with different inclination angles to 5 μm or less, and thus the correction lens made of the flexible optical plastic material. After being molded with a mold, it can be easily released from the mold.

As described above, by forming the step surface 4a ″ at an obtuse angle with respect to the reference surface, the exposure light incident on the area boundary portion and its vicinity interferes and is dispersed in a relatively wide area. However, the energy of the exposure light emitted from the portion affected by the area boundary of the correction lens is reduced,
This portion can generate a grid-like dark line pattern having a uniform width and contrast.

Further, as a means for further reducing the energy of the exposure light emitted from the portion affected by the region boundary portion of the correction lens, as shown in FIG. The surface roughness is deteriorated by inserting tens of lines. As a result, the light transmittance at the step surface 4a 'is reduced, and the light amount of the exposure light emitted from the portion affected by the area boundary portion of the correction lens can be further reduced.

Further, on the back surface of the area boundary portion, that is, on the side of the exit surface of the exposure light of the correction lens, a stripe or a scratch having a constant width is formed in the portion where the emitted light is affected by the area boundary portion. By roughening the surface and scattering the exposure light,
It is possible to compensate for the nonuniformity of the width of the grid-like dark line pattern, which is the largest cause of variations in the dot pattern formation. When the back surface is roughened like this, the step surface 4a '
Alternatively, the angle θ of 4a ″ does not have to be formed at a constant inclination with respect to the incident light for exposure, and for example, the angle θ may be formed to be constant. Further, the angle θ may be formed as a right angle or an acute angle.

That is, the correction lens 4 in the second embodiment has a dark line pattern generated on the exposure surface by the exposure light that has passed through the correction lens 4 and reached the exposure surface when the exposure light is irradiated. It suffices that the line width and the contrast become uniform over the entire exposed surface.

Next, a mold for molding the correction lens according to the present invention shown in FIG. 4 will be described.

FIG. 18 is a perspective view showing the outer appearance of a mold used for molding the correction lens according to the embodiment of the present invention shown in FIG. As a material of the mold 181, a nonferrous soft metal such as an aluminum alloy, brass, or copper is suitable from the viewpoint of workability described later. A plurality of flat surfaces or curved surfaces 181a having different inclinations with respect to the reference bottom surface 181c.
Is transferred as the uppermost point of the inclined surface of the correction lens to be molded. The surface of the mold 181 is formed corresponding to the transfer surface of the correction lens shown in FIG.

Next, a method of processing this die will be described.

FIG. 19 is a view showing a cutting device for a correction lens forming die of the present invention. FIG. 20 is a view showing a flowchart of the cutting process of the mold of the present invention.

The mold 191 is held on a positioning table 143 in the pitch direction on the Z table. On this mold surface, the transfer surface of the above-mentioned correction lens surface shape is cut using a cutting tool such as a diamond tool. The diamond cutting tool 144 is rotatably held on the rotary table 142 with the center of the cutting edge as the center of rotation, and is cut by the movement of the table 141 in the Y direction with respect to the die 181 to make the table 141 in the x direction. Is continuously moved to apply cutting feed.

Before performing this cutting, the angle θ with respect to the reference plane is calculated in advance from the uppermost point of the area boundary portion of the flat surface or curved surface to be processed, and the number of streaks and the optimum value are determined by the height of the step 181a. After determining the appropriate machining position and repeating this cycle in sequence to determine the machining position at the steps of all discontinuous boundaries, die cutting is performed.

As shown in FIG. 5, the step surface 4 at the region boundary portion
In order to deteriorate the surface roughness of a ', several steps are formed on the step surface 4a'.
When several tens of streaks are to be machined, when machining the step surface 181a of the die 181, the machining conditions are controlled so that the feed amount of the machining process changes at every desired pitch. As a result, the step surface 181a has a depth of 0. It is possible to generate stripe-shaped irregularities of several μm.

After cutting one plane or curved surface, the Z table 143 is pitch-fed, and the rotary table 142 is used to position the diamond cutting tool 144 at the desired inclination angle of the plane or curved surface 181b to be cut in the y direction. This is a processing method that changes sequentially during cutting.

The length of the cutting edge of the diamond cutting tool 144 in the direction perpendicular to the cutting direction x may be equal to or slightly longer than the length of one desired flat surface or curved surface 181b.

Using a mold processed by the above-described cutting method, supply the above-mentioned optical plastic such as polymethylmethacrylate having a high light transmittance or a thermosetting resin to the surface of the mold and heat-compress it. The correction lens is molded by. It is also possible to form the resin by supplying an ultraviolet curable resin to the surface of the mold and irradiating it with ultraviolet rays.

In the mold manufactured by the above-described cutting process, the size of the desired flat surface or curved surface 181b and the surface shape of the mold can be freely designed, so that a highly accurate correction lens can be manufactured. It will be possible.

Next, a method of exposing the photosensitive film on the inner surface of the face panel of the cathode ray tube by using the correction lens 4 of the present invention formed by the above-described processing method to form the dot pattern of the phosphor will be described. .

The method of forming the dot pattern of the phosphor is the same as the method described with reference to FIG. 8 in the section of the prior art as described in the first embodiment, and in the present invention, The conventional correction lens 83 in FIG. 8 is replaced with the correction lens 4 according to the present invention, and the exposure light (shown by the dotted line in the drawing) emitted from the light source 81 is corrected by the lens 82 and the correction lens 4.
And is projected onto the shadow mask 87. The correction lens 4 has a boundary surface (4a ″ or 4a ′) of the area boundary portion.
The obliquity angle with respect to the reference plane 4c is a constant obtuse angle, and
This correction is performed by deteriorating the surface roughness of this boundary surface or making a line or scratch of a certain width on the back surface of the area boundary part to roughen the surface and reduce the amount of exposure light transmitted from this part. The width and contrast of the grid-like dark lines generated by the exposure light that has passed through the lens can be made uniform.

When the correction lens 4 thus formed is used for exposure, the exposure light is emitted while the correction lens 4 is swung, so that the shadow mask 87 is exposed on the shadow mask 87 in a predetermined time as described above. Since the exposure light is uniformly irradiated, the exposure light passing through the shadow mask 87 is applied to the photosensitive film on the inner surface of the face panel of the cathode ray tube on the front surface of the exposure surface with a uniform distribution of the amount of applied light energy. It is irradiated across.

As a result, a dot pattern of a fluorescent film having good positional accuracy and shape accuracy is formed on the inner surface of the face panel of the cathode ray tube.

By adopting the color cathode ray tube, a high-definition television set and a terminal monitor can be obtained.

When the exposure effect of the color cathode ray tube manufactured according to this example was measured, the same result as that of the first example was obtained.

As described above, the means for carrying out the present invention is 2
Although described with reference to three embodiments, the invention is not limited to these embodiments. That is, the exposure correction lens for forming the dot pattern of the fluorescent film on the inner surface of the face panel of the color CRT in the present invention is composed of a plurality of minute flat surfaces or curved surfaces, and is irradiated with the exposure light. The line width of the light-dark line pattern or the dark line pattern generated in a grid pattern on the exposure surface and the contrast of the exposure light applied to the pattern and the exposure surface other than the pattern are uniform over the entire exposure surface. The method disclosed in the first embodiment and the method disclosed in the second embodiment may be combined, and the method disclosed in part of them may be used. You may.

For example, the correction lens is processed into the method and shape disclosed in the first embodiment on the side of the incident surface of the exposure light,
By forming a rough surface having a uniform width on the opposite side of the emission surface as disclosed in the second embodiment, bright and dark lines generated in a grid pattern on the exposure surface when the exposure light is irradiated. The line width of the pattern or the dark line pattern and the contrast of the exposure light applied to the pattern and the exposure surface other than the pattern are uniformly formed over the entire exposure surface.

According to the present invention, the line width of the grid-like bright and dark lines generated by the correction lens composed of a plurality of minute planes or curved surfaces and the contrast thereof are uniform over the entire exposed surface on the shadow mask. Therefore, by exposing the correction lens while swinging it, a fluorescent substance dot pattern with good shape accuracy and position accuracy is formed, and a cathode ray tube with good image quality can be obtained.

Furthermore, by using this CRT, a high-definition television set and a terminal monitor can be obtained.

[0092]

According to the present invention, the line width of the grid-like bright and dark lines generated by the correction lens composed of a plurality of minute planes or curved surfaces and the contrast thereof are spread over the entire exposed surface on the shadow mask. It is possible to obtain a cathode ray tube with good image quality by forming a fluorescent dot pattern with good shape accuracy and position accuracy by exposing while swinging this correction lens. it can.

Furthermore, by using this CRT, a high-definition television set and a terminal monitor can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing the outer appearance of a correction lens according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a correction lens according to Example 1 of the present invention.

FIG. 3 is a partially enlarged cross-sectional view of a conventional correction lens and a correction lens according to a first embodiment of the present invention and a comparison diagram of exposure effects.

FIG. 4 is a perspective view showing the appearance of a correction lens according to Example 3 of the present invention.

FIG. 5 is a sectional view of a correction lens according to Example 3 of the present invention.

FIG. 6 is a partially enlarged sectional view of a conventional correction lens.

FIG. 7 is a partially enlarged sectional view of a correction lens according to a third embodiment of the present invention.

FIG. 8 is a sectional view showing the structure of an exposure table.

FIG. 9 is a plan view and a sectional view of a conventional correction lens.

FIG. 10 is a plan view and a sectional view of a conventional correction lens.

FIG. 11 is a partially enlarged sectional view of a conventional correction lens.

FIG. 12 is a perspective view of a mold of a conventional correction lens.

FIG. 13 is a perspective view showing the outer appearance of a mold for molding the correction lens according to the first embodiment of the present invention.

FIG. 14 is a cutting device for a correction lens forming die according to the first embodiment of the present invention.

FIG. 15 is a flowchart of a cutting process of a mold for a correction lens according to the first embodiment of the present invention.

FIG. 16 is a plastic working apparatus for a correction lens forming die according to the first embodiment of the present invention.

FIG. 17 is a flowchart of the plastic working process of the mold of the correction lens according to the first embodiment of the present invention.

FIG. 18 is a perspective view showing the outer appearance of a mold for molding the correction lens according to the third embodiment of the present invention.

FIG. 19 is a cutting device for a correction lens forming die according to a third embodiment of the present invention.

FIG. 20 is a flowchart of a cutting process of a mold for a correction lens according to a third embodiment of the present invention.

FIG. 21 is a comparison diagram of exposure effects of the correction lens according to the first embodiment of the present invention and the conventional correction lens.

[Explanation of symbols]

3 ... Correction lens, 131 ... Correction lens mold, 3a, 3b, 3c ... Plural regions (lens surfaces) 4a, 4b, 4c ... Plural region boundary portions 141 ... XY table 142 ... Rotary table
143 ... Z table 144 ... Diamond bite 165 ... Punch 166 ... X direction goniometer stage 167 ... Y direction goniometer stage

[Procedure amendment]

[Submission date] March 18, 2003 (2003.3.1)
8)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

1. A fluorescent device comprising 1 million or more pixels.
Is provided on the inner surface of the face panel, and the phosphor dot pattern has a luminance variation rate of -0.15%.
To + 0.15% within the range
A color cathode ray tube.

Claims (4)

[Claims] 1. A color cathode ray tube having a face panel, wherein the face panel includes pixels each having a phosphor dot pattern formed by exposure through a shadow mask.
A color cathode-ray tube having at least 0,000 pieces and having a luminance variation rate of a screen constituted by the pixels within a range of -0.05% to + 0.05%. 2. A color display device having a color cathode ray tube, wherein the color cathode ray tube has one pixel including a phosphor dot pattern formed by exposure through a shadow mask.
It is equipped with a face panel having at least, 000,000 pieces, and the luminance variation rate of the screen constituted by the pixels is -0.05% to +
A color display device characterized in that it is within a range of 0.05%. 3. A face panel having 1 million or more pixels each composed of a phosphor dot pattern formed by exposing through a shadow mask, and when the back surface of the face panel is uniformly illuminated, The luminance variation rate of the screen based on the image signal detected from the front side of the face panel,
A color cathode ray tube characterized by being formed within a range of 0.15% to + 0.15%. 4. A color cathode-ray tube comprising a face panel having 1 million or more pixels each having a phosphor dot pattern formed by exposing through a shadow mask, and uniformly illuminating the back surface of the face panel. When I did
A color display device, wherein a brightness variation rate of a screen based on an image signal detected from the front side of the face panel is formed within a range of -0.15% to + 0.15%.