JP3233133B2 - Color CRT and color display device - Google Patents

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 phosphor screen dot pattern of a cathode ray tube used in an exposure process for forming a fluorescent film of a color cathode ray tube. The present invention relates to a high-definition and 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 As the definition of a color cathode ray tube is required to be higher, the accuracy required for an exposure process for forming a fluorescent screen by exposure and development is also increasing.

In the formation of a fluorescent screen of a color CRT of a black matrix type, a black body is formed leaving a large number of stripe-like or dot-like holes, and a stripe-like or dot-like fluorescent film is formed in these holes. .
Therefore, the position of the hole and the position of the phosphor film coincide with each other, but it is important to accurately position both of the hole and the phosphor film at the position where the electron beam is projected.

Various correction lenses have been used to perform the above-described alignment (registration correction). Some correction lenses have a continuous curved surface and others have a discontinuous curved surface. Therefore, it has a very complicated surface shape because it is intended to approximate the actual electron beam orbit.

In the color cathode ray tube having the stripe-shaped fluorescent film, the fluorescent film has a long strip shape in the vertical direction. Therefore, even if the electron beam projected to emit the light is displaced in the vertical direction. No color shift occurs. 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 screens cannot be arranged at high density, high resolution cannot be obtained. For this reason, a color cathode-ray tube for a computer terminal which requires high resolution has a dot-like fluorescent film formed thereon.

In forming a fluorescent film of a color cathode ray tube having the above-mentioned dot-shaped fluorescent film, horizontal and vertical corrections must be made at the same time, and various correction lenses are used to obtain an optimum correction amount. Is used.

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

FIG. 8 shows the structure of an exposure table.
A face panel 85 on which a shadow mask 87 is mounted is installed on an exposure table 84 in which a light source 81, a lens 82, and a correction lens 83 are built. The correction lens 83 is shown in FIG.
(C) as shown in plan view and horizontal direction (x);
It has a cross-sectional shape inclined 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
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. Pattern of the photosensitive film 8
In order to prevent the exposure of the correction lens 83, the correction lens 83 is swung in the x and y2 directions during the exposure processing. However, since the dot formation cannot be performed with high accuracy due to the influence of the lattice-like dark line pattern, various methods for suppressing the occurrence of various lattice-like dark line patterns have been attempted. For example, a correction lens disclosed in Japanese Patent Application 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 a grid-like dark line pattern to some extent. The effective surface of the correction lens is divided into a plurality of regions, the thickness at the center of the region 103a is d1, the thickness at the center of 103b is d2, the thickness at the center of 103c is d3, the thickness at the center of 103d is d4, Assuming that the thickness of the center of 103e is d5 and the thickness of the center of 103f is d6, these d1, d2, d3, d4, d5, and d6 are the steps 104a, 104b, 104c, 104d, and 104e between the respective regions.
It was about 00 μm. The contrast and area of the lattice-like dark line pattern (dark line fringe) on the phosphor screen are reduced by reducing each step.

[0010] However, even with the use of the above-mentioned correction lens, it has not been possible to satisfy the need for a high definition color CRT.

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

FIG. 12 is a perspective view of a mold of a conventional correction lens used for molding the correction lens. The correction lens mold 121 has a desired plurality of 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 related art is one mold by a combination of several hundred blocks corresponding to the area. It is a so-called assembly type. Therefore, in order to satisfy the demand for higher definition, it is very difficult to further reduce the area of each of the divided regions of the correction lens and to further reduce the step at the region boundary. I have.

When the light beam 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, FIG.
As described with reference to (a), a grid-like dark line pattern of non-uniform width is generated on the photosensitive film due to the step height of the boundary between different areas of the correction lens surface, and the dots on the color CRT fluorescent screen are varied. I do. That is, the amount of light reaching the photosensitive film becomes non-uniform, the shape accuracy of the phosphor dots is poor, and the position accuracy is also poor. For this reason, it has been difficult to obtain a high-definition color CRT with good image quality.

[0014]

In the above prior art, the width and contrast of the exposure light transmitted through the correction lens and irradiated onto the shadow mask is not good due to the step at the boundary between different areas of the correction lens surface. A uniform grid-like bright and dark line pattern is generated. As means for alleviating the influence of the grid-like light-dark line pattern, the thickness of the center of the lens plane is adjusted to reduce the occurrence of the grid-like light-dark line pattern, or at the time of exposure. By shaking 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, but the screen, which conventionally consisted of 400,000 pixels, is composed of 1 million or more pixels. It has not been possible to adequately respond to the need for high-definition color cathode-ray tubes to be attempted.

[0015] As described above, this is a CD of good image quality.
In order to obtain T, a high-precision phosphor dot position accuracy is required, and in order to obtain a high-accuracy phosphor dot position accuracy, it is necessary to form dots of a high-precision shape. This is because a high-precision correction lens to satisfy the condition was not obtained.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and eliminate the influence of a grid-like bright and dark line pattern generated by a correction lens at the time of exposure. It is an object of the present invention to provide a high-definition and high-quality CRT and a color CRT device in which the positions are formed with high precision.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to provide a light and dark line or a dark line pattern in a grid pattern generated by a correction lens having a plurality of planes or curved surfaces having different inclinations on an incident surface of exposure light. This is achieved by forming a correction lens so as to be uniform over the entire exposure surface, and exposing while oscillating the correction lens.

In the correction lens, a plurality of planes or curved surfaces having different inclinations formed on the lens surface are miniaturized to half to 1/3 or less of the conventional dimensions, and each of the miniaturized planes or curved surfaces is reduced. Each plane or curved surface is formed so that the step generated at the boundary is as small as possible. (1) The inclination of the step at the boundary is parallel to the incident direction of the exposure light, or
(2) The inclination of the step surface at the boundary is set to be equal to or less than 120 degrees with respect to the reference plane and to be constant with respect to the incident direction of the exposure light.
Alternatively, (3) the inclination of the step surface at 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 at the boundary portion is set as a reference. The angle is set to 120 degrees or less with respect to the surface, and stripes or scratches are formed with a certain width on a portion where the lattice-like dark line is emitted on the side of the exposure light emission surface of the correction lens to roughen the surface. ) To (4).

[0019]

By illuminating a shadow mask while oscillating the correction lens during exposure by making the width and contrast of a 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 certain 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 with good positional 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 described in the order described in the section for solving the above problems. By forming the surface parallel to the direction of incidence of the exposure light, the rate of secondary refraction on the stepped surface due to the exposure light is reduced, and the area affecting the exit surface is reduced. As a result, the line width due to the exposure light transmitted through the correction lens is narrow, and the contrast is constant.
A grid-like light and dark line pattern is generated.

(2) By making the inclination of the stepped surface at the boundary portion equal to or less than 120 degrees with respect to the reference plane and constant with respect to the incident direction of the exposure light, the exposure light incident on the stepped surface and its vicinity is exposed. Light interferes and scatters over a relatively large area, and the amount of exposure light emitted from a portion affected by the step surface of the correction lens is reduced, and this portion causes a grid-like dark line having a uniform width and contrast. A pattern occurs.

(3) By setting the inclination of the step surface at the boundary portion to 120 degrees or less with respect to the reference surface and forming minute irregularities on the surface of the step surface, the light transmittance on the step surface decreases. Therefore, the amount of exposure light emitted from the portion of the correction lens affected by the step surface is further reduced as compared with the case of the above (2), and the dark line pattern having a uniform width and contrast is formed by this portion. Occurs.

(4) The inclination of the step surface at the boundary is set to 120 degrees or less with respect to the reference plane, and a stripe having a constant width is formed at a portion where a lattice-like dark line is emitted on the side of the exposure light emission surface of the correction lens. Alternatively, by forming a flaw or the like to roughen the surface, a lattice-like dark line pattern having a uniform width and uniform contrast is generated by this portion.

[0024]

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

Embodiment 1 FIG. 1 is a perspective view showing the appearance of a correction lens according to one 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 polymethyl methacrylate having a high light transmittance, and a plurality of planes having different inclinations in the x and y directions with respect to the reference plane 2 or curved surfaces. 3a is formed.

The correction lens according to the present invention shown in FIG.
It has a shape similar to the correction lenses shown in FIG. 9 manufactured by the prior art, but these correction lenses are conventionally formed one by one using an assembling mold. While each flat or curved surface is formed by a die, in the present invention, each flat or curved die is formed by using an integrated die formed by machining one die material surface.

As described above, since the correction lens is molded by using the integral mold, the correction lens 3 is conventionally formed to have a plurality of planes having different inclinations or the minimum length of each side of the curved surface 3a. Therefore, the dimension of each side of the flat surface or the curved surface 3a is reduced by half to 1 times as compared with the dimension of each side formed by the conventional assembling mold. / 3 or less.

Further, the integral type is arranged such that each plane or curved surface is positioned such that the value of the largest step among the planes having the inclination angles or the boundaries of the curved surfaces becomes the smallest (minimum). By determining the processing conditions, a conventional correction lens formed using an assembling mold has a 100
The step at the boundary, which was about μm, can be reduced to 5 μm or less.

Further, since an integrated mold for forming the above-mentioned correction lens is formed by machining by a method as described later, in the present invention, the step 4a at the lens surface boundary portion is formed in a lattice shape generated by the step 4a. Can be formed at various angles in accordance with the degree of occurrence of light and dark lines.

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

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

Step 3 at the boundary between the lens surfaces of the conventional correction lens
4a is configured to be perpendicular to the reference plane 32, and the incident angle of the exposure light incident on the lens surface boundary step 34a varies depending on the location. The light quantity and the width of the lattice-like bright and dark line pattern of the outgoing light generated due to the partial concentration or dispersion of the light due to the secondary refraction of the incident light cause a change (distribution) depending on the place.

On the other hand, in the correction lens according to the present invention, the step 4a at the lens surface boundary portion is formed to be 1/20 or less as compared with the conventional correction lens. The light quantity and the width of the grid-like light and dark lines generated by light can be made substantially uniform over the entire exposure surface.

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

As described above, the step shape 4a at the lens surface boundary portion is obtained.
Is formed so that the inclination direction of the light is parallel to the incident direction of the exposure light incident on the correction lens, so that the ratio of the incident light that is refracted secondarily on the stepped surface is reduced. The light amount of the light and dark lines can be reduced substantially uniformly over the entire surface of the exposure surface, and the width of the light and dark lines can be reduced substantially uniformly over the entire surface of the exposure 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 appearance of a mold used for molding the correction lens according to the embodiment of the present invention shown in FIG. As a material for the mold 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 mold 131 is formed to correspond to the transfer surface of the correction lens shown in FIG.

Next, a method of working this mold will be described.

FIG. 14 is a view showing an apparatus for cutting a molding die for a correction lens according to the present invention.

FIG. 15 is a view showing a flowchart of the cutting process of the mold according to the present invention.

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

Before performing this cutting, the height of the step 4a at the discontinuous boundary is calculated in advance based on the inclination angle of the plane or the curved surface 3a of the correction lens of the present invention, and the maximum value of the step is minimized. Correction lens 3 optimized to be (minimal)
Determine the shape of Further, 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 a trigonometric function, the maximum value of the step is minimized, and the inclination direction of the side wall at the lens surface boundary is exposed from the light source. Processing conditions are determined so as to be parallel to the incident direction of the working light. This cycle is sequentially repeated, and after the machining positions at the steps of all the discontinuous boundaries are determined, die cutting is performed.

In accordance with the position of the cutting feed, every time the cutting of one plane or curved surface 133 is completed, the pitch feed of the Z table 143 is performed, and then the plane or curved surface 133 to be cut is moved in the desired y direction. The position of the diamond cutting tool 144 is sequentially changed during the cutting by the rotary table 142 at the inclination angle, and processing is performed. 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 one desired flat surface or the side of the 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 of a molding die for a correction lens according to the present invention.

The mold 164 is held on a positioning table 163 held so as to be movable in two orthogonal axes in an x table and a y table. A reference bottom surface 1 is placed on this mold surface.
A plurality of planes or curved surfaces 1 having different inclinations with respect to 32
The gonio stages 166 and 167 are rotatable around the machined surface of the punch 165 for forming the punch 33.
And the gonio stage is attached to the lower end of the z-axis 168 that can move in the vertical direction. A control device 169 including a force sensor for controlling and managing the pressing force of the punch 165 on the processing surface is also attached to the lower end of the z-axis 168. This z-axis 168 is a column 170
Is held at

Next, a description will be given of a processing process of a molding die for a correction lens using the present apparatus.

FIG. 17 is a view showing a flowchart of the plastic working process of the mold according to the present invention. Before performing die processing, the height of the step 134 at the discontinuous boundary is calculated in advance based on the inclination angle of the plane or the curved surface 133 to be processed, and the processing position where the step is minimized is determined. If the shape is such that bright / dark lines are likely to occur, the incident angle of the incident light is calculated from the light source, the contact point with the adjacent inclined surface is obtained from the trigonometric function, and the step is minimized and the inclination direction of the lens surface boundary side wall is the light source. Is determined so as to be parallel to. This cycle is sequentially repeated to determine the processing position at the step at all the discontinuous boundary portions, and then perform the die processing.

As the material of the punch 165, a high-hardness material such as diamond, CBN or carbide 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 curved surface 133. Processed in advance.
The gonio stage 166 in the x direction and the y in the y direction are adjusted so that the posture of the punch 165 with respect to the mold 164 coincides with the inclination in the x and y directions with respect to the reference bottom surface 132 required for the work surface.
The gonio stage 167 in each direction is positioned by a driving source such as a pulse motor. The punch and the mold 164
Relative positioning in the xy plane is performed by driving the x table and the y table.

After performing the relative positioning, the punch 16
5 is pressed, the surface of the mold 164 is pressed, and a control device 169 including a force sensor controls and manages the pressing force, and a desired flat surface or curved surface 133 is provided.
Is formed, the posture of the punch 165 is changed to form a step shape at the boundary between the lens surfaces. This cycle is sequentially repeated to process the mold.

The above-mentioned processing method is to form a mold of the correction lens of the present invention by using a plastic processing method.

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

In a mold manufactured by the above-described two types of processing processes, the plastic working method and the cutting working method, a desired flat surface or the size of the curved surface 133 and the surface shape of the mold can be freely designed. 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 for forming a dot pattern of a phosphor by exposing a photosensitive film on the inner surface of a face panel of a cathode ray tube using the correction lens according to the present invention formed by the above-described processing method 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, and in the present invention, the conventional correction lens 83 in FIG. Light source 8 instead of the correction lens 3
Exposure light (indicated by a dotted line in the figure) emitted from 1
The light passes through the correction mask 2 and the correction lens 3 and is irradiated onto the shadow mask 87. At this time, by oscillating the correction lens 3, the exposure light is uniformly irradiated on the shadow mask 87 within a predetermined time as described above, so that the exposure light that has passed through the shadow mask 87 is a cathode ray tube. The photosensitive film on the inner surface of the face panel is uniformly irradiated over the entire exposed surface in a state where the distribution of the irradiated light amount is uniform.

By using the uniformly exposed photosensitive film as a mask and etching the fluorescent film formed under the photosensitive film layer, 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.

By employing the color cathode ray tube manufactured by the above method, a high definition television set and a monitor for a terminal can be obtained.

Next, the results of evaluation of the CRT face panel produced by the above method will be described.

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

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

The face panel 85 of the cathode ray tube manufactured by the above-described method is generally provided with a vertical direction (y in FIG. 21).
21), it is easy to generate streak-like luminance unevenness in the horizontal direction (FIG. 21). (X direction) was evaluated.

Here, as an index for evaluating the change in luminance, the luminance change as defined by the following equation (the luminance at each point in the x direction in the predetermined range 211 of the fluorescent screen 210 of the cathode ray tube added in the y direction). Is differentiated by the second order at the coordinates x of each point) and the luminance variation rate.

Brightness fluctuation = d ² (brightness) / dx ²

[0067]

(Equation 1)

Here, the luminance fluctuation defined above has a good correlation with the streak unevenness which is confirmed when the predetermined range 211 of the cathode ray tube fluorescent screen 210 which is the measurement surface is visually observed. In order to obtain a high-quality cathode ray tube in which the streak unevenness cannot be confirmed by visual observation, it is necessary to make the luminance fluctuation small and the luminance fluctuation rate to be ± 0.15% or less. Is experimentally required by

In the present invention, the correction lens used for exposure is
The length of one side of the plane or curved surface constituting the lens surface is subdivided into half to 1/3 or less than that of the conventional one, and the energy of light applied to the exposure surface at the time of forming the phosphor screen pattern is partially varied. In order not to be connected, the boundary step between a plurality of planes or curved surfaces with different inclinations with respect to the reference plane is minimized,
By forming such that the inclination direction of the boundary side wall is parallel to the optical path of the light incident from the light source, and performing the exposure while oscillating the correction lens, uniform exposure is realized over the entire exposure surface, By reducing the luminance fluctuation rate to ± 0.05% or less with respect to the conventional correction lens of ± 0.35%, the target luminance fluctuation rate of ± 0.15% or less could be achieved. .

FIG. 21 shows a typical example according to the present invention. A plurality of face panels of a CRT based on the above embodiment were prepared, and their luminance fluctuations were measured to determine the luminance fluctuation rate. All of them could achieve the above-mentioned target luminance variation rate ± 0.15% or less.

That is, by reducing the width of the grid-like bright / dark line pattern which deteriorates the exposure effect, the accuracy of the fluorescent film pattern, that is, the position accuracy and the shape accuracy of the dot pattern is improved, and the high definition is achieved. It can be seen that a color CRT was obtained.

Embodiment 2 FIG. FIG. 4 is a perspective view showing the appearance of a correction lens according to another embodiment of the present invention. FIG. 5 is a cross-sectional view of a correction lens according to another embodiment of the present invention in FIG. FIG. 6 is a partially enlarged cross-sectional view of a conventional correction lens. FIG.
FIG. 5 is a partially enlarged sectional view of a correction lens according to another embodiment of the present invention in FIG.

The correction lens 4 is made of an optical plastic such as polymethyl methacrylate having a high light transmittance, and has a plurality of planes 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 prior art, but as shown in FIG. 7, a plurality of flat or curved area boundaries having different inclination angles of the correction lens. When the angle θ of the step surface 4a ″ of the portion with respect to the reference surface 4c is equal to or less than 120 °, the portion is formed to have a constant inclination with respect to the incident exposure light. In general, a lens having such a shape cannot be molded in consideration of mold releasability from a mold for molding a correction lens. However, in the present invention, the mold has a correction lens surface shape formed by a subdivided flat surface or curved surface. Since the transfer surface is formed, the height of the step at the region boundary portion of the region having a plurality of planes or curved surfaces having different inclination angles can be reduced to 5 μm or less, so that the correction lens is made of a flexible optical plastic material. Can be easily released from this mold after being molded in the mold.

As described above, by forming the step surface 4a '' at an obtuse angle with respect to the reference plane, the exposure light incident on the region boundary portion and its vicinity interferes with each other and disperses into a relatively wide region. The energy of the exposure light emitted from the portion affected by the region boundary of the correction lens is reduced,
With this portion, a grid-like dark line pattern having a uniform width and contrast can be generated.

As means for further reducing the energy of the exposure light emitted from the portion of the correction lens affected by the region boundary, as shown in FIG. 5, several steps are formed on the step surface 4a 'at the region boundary. Surface roughness is degraded by inserting tens of lines. As a result, the transmittance of light on the step surface 4a 'decreases, and the amount of exposure light emitted from the portion affected by the region boundary of the correction lens can be further reduced.

Further, a streak or a flaw or the like having a constant width is formed on the back surface of the region boundary, that is, on the portion where the emitted light is affected by the region boundary on the side of the exposure light emission surface of the correction lens. By scattering the light for exposure,
It is possible to compensate for the unevenness of the width of the lattice-like dark line pattern, which is the largest cause of the occurrence of variation during dot pattern formation. When the back surface is roughened in this way, the step surface 4a '
Alternatively, it is not necessary to form the angle θ of 4a ″ at a constant inclination with respect to the incident exposure light. For example, the angle θ may be formed to be constant. Further, the angle θ may be formed to be a right angle or an acute angle.

That is, the correcting 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 was irradiated. It is only necessary that the line width and the contrast be 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 appearance of a mold used for molding the correction lens according to one embodiment of the present invention shown in FIG. As a material of the mold 181, a non-ferrous soft metal such as an aluminum alloy, brass, or copper is suitable from the viewpoint of workability described later. A plurality of planes having different inclinations with respect to the reference bottom surface 181c, or a curved surface 181a
Is transferred as the highest point of the inclined surface of the correction lens to be formed. The surface of the mold 181 is formed corresponding to the transfer surface of the correction lens shown in FIG.

Next, a method of working this mold will be described.

FIG. 19 is a view showing an apparatus for cutting a molding die for a correction lens according to the present invention.

FIG. 20 is a view showing a flow chart of the die cutting process of the present invention.

The mold 191 is held on a positioning table 143 in the pitch direction of the Z table. The transfer surface of the correction lens surface shape described above is cut on the die surface by 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 tip of the cutting edge as a center of rotation. The cutting is given to the mold 181 by moving the table 141 in the Y direction, and the table 141 is moved in the x direction. Is moved continuously to apply cutting feed.

Before performing this cutting, an angle θ with respect to the reference plane is calculated in advance from the highest point of the boundary of the plane or curved surface to be processed with respect to the reference plane. This cycle is sequentially repeated to determine the machining position at the step at all the discontinuous boundaries, and then die cutting is performed.

As shown in FIG. 5, the step surface 4 at the region boundary portion
In order to degrade the surface roughness of a ', several steps
In the case of processing with dozens of streaks, the cutting conditions are controlled so that the feed amount of the cutting changes at every desired pitch when the step surface 181a of the mold 181 is processed. As a result, a depth of 0.1 mm is formed on the step surface 181a. Streak-like irregularities of several μm can be generated.

After cutting a row of planes or curved surfaces, the Z table 143 is pitch-fed, and then the attitude of the diamond cutting tool 144 is adjusted by the rotary table 142 to the desired y-direction inclination angle of the plane or curved surface 181b to be cut. 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 one desired flat surface or one side of the curved surface 181b.

An optical plastic or a thermosetting resin such as polymethyl methacrylate having a high light transmittance is supplied to the surface of the mold by using a mold processed by the above-mentioned cutting method, and is heated and compressed. To form a correction lens. The molding can also be carried out by supplying an ultraviolet-curable resin to the surface of the mold and irradiating it with ultraviolet light.

In the mold manufactured by the above-described machining 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 becomes possible.

Next, a method of exposing a photosensitive film on the inner surface of the face panel of a CRT using the correction lens 4 according to the present invention formed by the above-described processing method to form a dot pattern of a 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. The conventional correction lens 83 in FIG. 8 is replaced with the correction lens 4 according to the present invention, and the exposure light (indicated by a dotted line in FIG.
And irradiates it on the shadow mask 87. The correction lens 4 is provided at the boundary surface (4a '' or 4a ') of the region boundary.
Is a constant obtuse angle with respect to the reference plane 4c,
This correction can be made by deteriorating the surface roughness of this boundary surface, or by putting streaks or scratches of a fixed width on the back surface of the region boundary to roughen the surface and reduce the amount of transmission of exposure light from this part. The width and contrast of the grid-like dark line generated by the exposure light transmitted through the lens can be made uniform.

When exposure is performed using the correction lens 4 formed as described above, the exposure light is irradiated while the correction lens 4 is oscillating, so that the shadow mask 87 is placed on the shadow mask 87 for a predetermined time as described above. Since the light for exposure is uniformly irradiated, the light for exposure that has passed through the shadow mask 87 is deposited on the photosensitive film on the inner surface of the face panel of the cathode ray tube, and is distributed on the front surface of the exposed surface in a state where the distribution of the light energy to be irradiated is uniform. 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.

Further, by employing the above 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 the present embodiment was measured, the same result as in the first embodiment was obtained.

As described above, the means for practicing the present invention are as follows.
Although described using one embodiment, the present 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 cathode ray tube according to the present invention is configured by a plurality of minute planes or curved surfaces, and irradiates the exposure light. The line width of the light and dark line pattern or the dark line pattern that occurs in a grid pattern on the exposed surface, and the contrast between the pattern and the exposure light irradiated on the exposed surface other than the pattern is uniform over the entire exposed surface. The method disclosed in the first embodiment and the method disclosed in the second embodiment may be combined as long as they are formed as described above. You may.

For example, the correction lens is processed into the method and the 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 as disclosed in the second embodiment on the opposite side of the emission surface, light-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 between the pattern and the exposure light applied to the exposure surface other than the pattern are uniformly formed over the entire exposure surface.

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

Further, by using this cathode ray tube, a high definition television set and a monitor for a terminal can be obtained.

[0101]

According to the present invention, the line width and contrast of the grid-like light and dark lines generated by the correction lens constituted by a plurality of minute planes or curved surfaces are adjusted over the entire exposure surface on the shadow mask. By exposing while oscillating this correction lens, a phosphor dot pattern with good shape accuracy and positional accuracy can be formed, and a cathode ray tube with good image quality can be obtained. it can.

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

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an 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 the first embodiment of the present invention.

FIG. 3 is a partially enlarged cross-sectional view of a conventional correction lens and a correction lens according to Example 1 of the present invention, and a comparison diagram of an exposure effect.

FIG. 4 is a perspective view illustrating an appearance of a correction lens according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a correction lens according to a third embodiment 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 a configuration of an exposure table.

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

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

FIG. 11 is a partially enlarged cross-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 appearance of a mold for forming a correction lens according to the first embodiment of the present invention.

FIG. 14 is an apparatus for cutting a molding die for a correction lens according to the first embodiment of the present invention.

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

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

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

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

FIG. 19 is an apparatus for cutting a molding die for a correction lens according to a third embodiment of the present invention.

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

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

[Explanation of symbols]

Reference numeral 3 denotes a correction lens; 131 denotes a correction lens mold; 3a, 3b, 3c; a plurality of areas (lens surfaces) 4
a, 4b, 4c a plurality of area boundaries 141 ... an XY table 142 ... a rotary table 143 ... a Z table 144 ... a diamond bite 165 ... a punch 1
66 ... X-direction goniometer stage 167 ... Y-direction goniometer stage

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01J 9/227

Claims (2)

(57) [Claims] An exposure light is formed by a plurality of planes or curved surfaces, and a step surface between the adjacent planes or curved surfaces is provided with a light for exposure through a correction lens formed in parallel with an incident direction of the light for exposure. A method of manufacturing a color cathode ray tube, which comprises irradiating to form pixels comprising a phosphor dot pattern on a face panel. 2. A method according to claim 1, wherein the exposure light passes through a correction lens formed of a plurality of flat surfaces or curved surfaces, and a step between the adjacent flat surfaces or curved surfaces is formed in parallel with the direction of incidence of the exposure light. A method for manufacturing a color display device, comprising irradiating a pixel with a phosphor dot pattern on a face panel.