JP3812293B2 - Manufacturing method of color cathode ray tube - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a color cathode ray tube, and more particularly to a method for forming a phosphor screen on the inner surface of a front panel.
[0002]
[Prior art]
FIG. 4 shows a partially cutaway perspective view of the color cathode ray tube apparatus. The color cathode ray tube apparatus includes a glass envelope comprising a front panel 1, a funnel 91 and a neck portion 92, an electron gun 93 enclosed in the neck portion 92, and a deflection yoke for deflecting an electron beam 94 emitted from the electron gun 93. 95, a phosphor screen surface 96, a color selection electrode 97 and a magnetic shield 98 which are disposed on the phosphor screen surface on the electron gun 93 side with a predetermined interval. As shown in the cross-sectional view of FIG. 2B, the phosphor screen surface 96 is provided with a black film 99 at a predetermined position on the inner surface of the front panel 1, on which red, green, and blue phosphor stripes are formed. 3, 4, and 5 are formed with a predetermined positional relationship, and a reflection film (not shown) such as aluminum is provided thereon. The phosphor films of the respective colors emit light when irradiated with the electron beam 94 that reaches through the color selection electrode 97.
[0003]
A slurry method is generally used as a method for producing a phosphor screen surface of a color cathode ray tube. A slurry in which phosphor powder is suspended in a photoresist obtained by adding an aqueous solution of ammonium dichromate (ADC) to an aqueous solution of polyvinyl alcohol (PVA), as shown in FIG. Inject while rotating slowly and then spread gently (arrows indicate the direction of rotation). After the slurry has spread over the entire inner surface of the front panel, as shown in FIG. 5 (b), a phosphor film having a uniform thickness is formed by swinging off the excess slurry by rotating the front panel at a high speed while tilting the front panel. Thereafter, the phosphor film is dried with a heater, warm air, or the like. Next, the color selection electrode is mounted at a predetermined position on the inner surface of the front panel, exposed, and developed with warm water or the like to form a phosphor film pattern of a predetermined color. This process is sequentially performed on the phosphors of three colors of green, blue, and red to form a predetermined pattern of three colors. Thereafter, an organic filming film is formed, and an aluminum vapor deposition film is formed thereon, whereby the phosphor screen surface of the color cathode ray tube is completed.
[0004]
One of the important things in the method of manufacturing the phosphor screen is to make the phosphor film thickness uniform in the swing-off process. If the film thickness of the phosphor film is non-uniform, the amount of light emitted from the phosphor becomes non-uniform, resulting in uneven brightness on the screen. Further, when a film thickness difference due to the position of the front panel and a luminance difference associated therewith occur in each of the three color phosphors, the luminance ratio of the three colors varies depending on the position of the front panel, and the white quality is significantly impaired. As a technique for improving / improving this, for example, in Japanese Patent Application Laid-Open No. 59-186230 and Japanese Patent Application Laid-Open No. 6-203752, a combination of swinging upward on the inner surface of the front panel and swinging downward on the inner surface of the front panel after slurry injection / spreading. Thus, it is disclosed that the phosphor film thickness is made uniform.
[0005]
[Problems to be solved by the invention]
However, when trying to carry out the method as described above, excessive slurry that splashes from the front panel corner during the swing-off rotation is prevented from splashing back to the inner surface of the front panel. A surplus slurry recovery facility is required, and a two-stage process is required.
[0006]
As a method for recovering surplus slurry other than the above, a small surplus slurry recovery box is installed at each corner of the front panel by using the centrifugal force of rotating the front panel to collect and discharge the surplus slurry. In addition, there is a method in which surplus slurry is collected and held by centrifugal force. However, since the surplus slurry is held in the collection box until the end of the rotation after the drying step, the surplus slurry is easily deteriorated due to heat from the drying step, which is disadvantageous for reuse.
[0007]
Therefore, in general, as shown in FIG. 6, after the slurry is spread and deposited on the entire inner surface of the front panel in the upward front panel tilt, the front panel is quickly tilted downward with a gentle rotation to Excess slurry is discharged downward, and while maintaining this angle, the phosphor film thickness is made uniform and further excess slurry is discharged by high-speed rotation. According to this method, it was possible to form a phosphor film having a uniform film thickness without deterioration of the recovered slurry with a one-step recovery facility.
[0008]
However, if the inclination angle when the front panel inner surface is vertically upward is 0 ° and the vertical downward angle is 180 °, the larger the inclination, the more the excess slurry is discharged, but at the same time the phosphor particles deposited on the inner surface of the front panel Floats downward due to gravity and is easy to fall. In particular, when forming the second and third color phosphor films, the centrifugal force applied to the phosphor particles due to the rotation during the swing-off process and the drying process is combined with gravity, so that the phosphors easily fall off. There is a problem that the packing density of the resin becomes low. This is remarkable at the part where the direction of centrifugal force and the direction of the groove formed by the phosphor film pattern of the first color or the second color coincide (stripe direction near the center in the stripe pattern, diagonal direction in the dot pattern). is there.
[0009]
And, as the radius of curvature of the front panel inner surface increases, that is, the closer to the plane, the smaller the component of the force that the phosphor particles are restrained on the inner surface of the front panel in the centrifugal force of the front panel rotation. Become prominent. On the other hand, when the inclination of the front panel is reduced in the swing-off process, the excess slurry tends to accumulate on the inner wall of the front panel, and unevenness tends to occur on the inner surface of the front panel. When forming the phosphor film of the first color, there is no groove direction formed by the phosphor film pattern on the front panel, so that the packing density of the phosphor particles does not decrease locally.
[0010]
The present invention has been made on the basis of the above circumstances, and provides a method for achieving both sufficient slurry discharge and uniform phosphor film formation without phosphor dropping even when the curvature of the inner surface of the front panel increases. It is the purpose.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the method of manufacturing a color cathode ray tube according to the present invention includes a step of forming a phosphor stripe pattern on the inner surface of the front panel two or more times while changing the tilt angle and rotation speed of the front panel. By repeating the above, a method for manufacturing a color cathode ray tube that forms a desired phosphor screen on the inner surface of the front panel, the second panel and subsequent phosphor stripe patterns are formed at a tilt angle of the front panel. An application step of spreading phosphor slurry on the inner surface of the front panel by rotating the front panel around its central axis at a predetermined rotational speed, and then the inclination angle of the front panel Is set to 105 ° or more and 130 ° or less so that the inner surface of the front panel is vertically inclined downward, and the front panel is predetermined around its central axis. A discharge step of discharging the excess amount of the phosphor slurry vertically from the inner surface of the front panel by rotating at a rotation speed of the front panel, and subsequently, an angle smaller than the inclination angle in the discharge step. in and with to return to an angle exceeding 90 °, by rotating the front panel with a large rotational speed than the rotational speed in the discharging process to about its central axis, with further discharging the excess of the phosphor slurry And a swing-off step for making the thickness of the phosphor slurry film on the inner surface of the front panel uniform (however, the inclination angle of the front panel is 0 when the inner surface of the front panel is vertically upward). °, 180 ° when vertically downward).
[0012]
After the phosphor slurry is spread and deposited on the inner surface of the front panel in this way, the front panel is quickly tilted downward by gentle rotation, and most of the excess slurry is discharged downward, and the phosphor film is rotated at high speed. In the process of forming a phosphor film by making the thickness uniform and further discharging excess slurry, the front panel is tilted downward to an angle at which excess slurry can be sufficiently discharged, and the tilt is returned quickly and uniformly. After the surplus slurry is discharged by performing the swing-off rotation for the conversion, it is possible to shift to the swing-off process while minimizing the lifting of the phosphor particles in the downward direction due to gravity. It is possible to simultaneously suppress unevenness due to the detachment and dropping of the phosphor particles.
[0014]
Further, it is preferable to the shake-off the inclination angle of the front panel 95 ° or more in the step (claim 2). If it does in this way, generation | occurrence | production of the return nonuniformity by the rebound of the surplus slurry from the surplus slurry collection | recovery equipment in a swing-off process can be suppressed.
[0015]
Further, an inclination angle of the front panel, it is preferable that the difference is made to be 5 ° or more and 20 ° or less and the discharge step and the shake-off process (Claim 3). If it does in this way, generation | occurrence | production of the nonuniformity by the scattering to the front panel inner surface of the fluorescent substance particle at the time of transfer from a discharge process to a swing-off process can be suppressed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
(First embodiment)
An embodiment in which the present invention is applied to formation of a phosphor stripe pattern of the third color will be described.
[0018]
FIG. 1 is a schematic diagram showing a change in the front panel tilt angle and the behavior of slurry on the inner surface of the front panel according to the embodiment of the present invention. The front panel 1 has an outer diameter of 500 [mm] × 700 [mm], and an inner surface curvature is about 10000 [mm] in radius. The phosphor slurry 2 to be injected is obtained by suspending about 30% of a red phosphor powder in a photoresist obtained by adding an ammonium dichromate (ADC) aqueous solution to a polyvinyl alcohol (PVA) aqueous solution. The front panel tilt angle is 0 ° when the inner surface is vertically upward, and θ represents the angle formed by the axis perpendicular to the front panel face and the vertical axis. In the drawings, for the sake of convenience, the angle between the front panel face surface and the horizontal plane is shown.
[0019]
In the front panel after the phosphor stripe pattern up to the second color is formed, as shown in FIG. 1 (a), the tilt angle θ of the front panel 1 is set to 14 ° (not shown), and the rotation speed at the time of injection is set. After injecting 200 [ml] of slurry at 15 [rpm], the slurry is kept at 40 [sec] at a low rotation of 6 [rpm] and spread over the entire inner surface of the front panel (the arrow indicates the direction of rotation). Subsequently, while the surplus slurry is discharged by quickly changing the inclination angle of the front panel 1 to 110 ° ((b) in the figure), it is continuously and promptly returned to 100 ° and 17 at 150 [rpm]. During [sec], the film thickness is made uniform by shaking off and further excess slurry is discharged ((c) in the figure). Thereafter, the coating process is completed through a drying process, and a phosphor film is completed through an exposure / development process.
[0020]
FIG. 2 is a schematic cross-sectional view of the front panel showing the degree of filling of the phosphor particles at the end of the coating process in the phosphor slurry of the third color according to the present embodiment. Further, FIG. 7 shows a cross section of the front panel of the conventional example (FIG. 5) in which the front panel inclination angle in the surplus slurry discharging step and the swing-off step is 110 ° for comparison.
[0021]
In the conventional example, a force to move radially to the phosphor particles is exerted by the centrifugal force at the time of swinging rotation. At this time, as shown in FIG. 6A, the phosphor particles 5 of the third color deposited between the stripes of the phosphor particles 3 of the first color and the stripes of the phosphor particles 4 of the second color are phosphor particles. The movement is restricted in the direction perpendicular to the three and four stripes, but not in the parallel direction. At the position of the same radial distance from the center of the front panel 1, the force applied in the parallel direction increases as the stripe portion is closer to the center. As a result of the synergistic effect of the phosphor particles 5 floating from the front panel 1 due to the front panel 1 facing downward, the movement of the phosphor particles 5 increases in the stripe portion closer to the center, as shown in FIG. As shown, the degree of filling of the stripes of the phosphor particles 5 becomes low.
[0022]
On the other hand, in the present embodiment, while discharging the surplus slurry without unevenness at a 110 ° inclination (FIG. 1B), the swinging off process is performed by continuously returning to the 100 ° inclination (FIG. 1C). )). Thereby, as shown to Fig.2 (a), the floating of the front panel of a fluorescent substance particle can be suppressed, and the filling degree of particle | grains improves significantly compared with a prior art example (FIG.2 (b)). Further, when the swing-off angle is 95 °, the quality is further improved.
[0023]
If the excess slurry is discharged at an angle of 105 ° or more, the inner surface of the front panel is not uneven. However, if the angle is too large, the phosphor particles tend to float, so it is desirable that the angle be 130 ° or less.
[0024]
The swing-off angle is set to an angle smaller than the discharge angle, that is, an angle smaller than 130 ° at the maximum. However, if the angle is 90 ° or less, surplus slurry that has flew to the upper inside of the recovery facility will bounce back into the front panel and cause unevenness. Therefore, the angle exceeds 90 °, preferably 95 ° or more.
[0025]
If the difference between the excess slurry discharge angle and the swing-off angle is too large, the phosphor particles are likely to be scattered on the inner surface of the front panel when returning to the swing-off angle, and unevenness is likely to occur. This angle difference is preferably 5 ° or more and 20 ° or less, but in the experiment, it was particularly good within 15 °.
[0026]
In the present embodiment, the front panel having an inner surface radius of curvature of about 10,000 [mm] has been described as an example. However, the appropriate angle slightly changes depending on the curvature of the inner surface. If the radius of curvature decreases, the resistance force from the inner curved surface against the centrifugal force acting on the phosphor particles increases, so that the angle can be set large.
[0027]
(Second Embodiment)
An embodiment in which the present invention is applied to formation of a phosphor stripe pattern of the second color will be described.
[0028]
In the front panel after the phosphor stripe pattern of the first color is formed, 200 [ml] of slurry is injected at a rotation speed of 15 [rpm] at a front panel tilt angle θ of 14 °, and then 6 [ [rpm] is maintained at 40 [sec] at a low rotation speed and spreads over the entire inner surface of the front panel, and then the front panel is quickly tilted to 110 [deg.] and the excess slurry is discharged and continuously returned to 100 [deg.] 150 [rpm ] For 17 [sec], the film thickness is made uniform by shaking off and further excess slurry is discharged, the coating process is completed through the drying process, and the phosphor film is completed through the exposure and development processes.
[0029]
FIG. 3 is a schematic cross-sectional view showing the filling degree of the phosphor particles at the end of the coating process in the phosphor slurry of the second color according to the present embodiment. Further, FIG. 7 shows, for comparison, the case of a conventional example as shown in FIG. 5 in which the front panel inclination angle at the time of discharging excess slurry and swinging off is 110 °.
[0030]
Similar to the first embodiment, in the conventional example, a force to move radially in the radial direction acts on the phosphor particles by the centrifugal force during the swing-off rotation. At this time, as shown in FIG. 7A, the movement of the second-color phosphor particles 4 deposited between the first-color phosphor stripes 3 and 3 is restricted in a direction perpendicular to the phosphor stripe 3. However, the direction parallel to the stripe 3 is not restricted. At a position at the same radial distance from the front panel center, the direction of the force applied in the parallel direction becomes greater as the stripe portion is closer to the center. As a result of a synergistic effect with the floating of the particles from the front panel due to the front panel facing downward, the movement of the particles becomes larger in the stripe portion closer to the center, and the degree of filling becomes lower as shown in FIG. 7B. .
[0031]
On the other hand, in the present embodiment, while discharging the surplus slurry without unevenness at a 110 ° inclination (FIG. 1B), the swinging off process is performed by continuously returning to the 100 ° inclination (FIG. 1C). )). Thereby, as shown to Fig.3 (a), the floating of the front panel of a fluorescent substance particle can be suppressed, and the filling degree of particle | grains improves significantly compared with a prior art example (FIG.3 (b)). Further, when the swing-off angle is 95 °, the quality is further improved.
[0032]
As in the first embodiment, if the excess slurry discharge angle is 105 ° or more and 130 ° or less, the front panel inner surface will not be uneven. If the swing-off angle is less than 95 °, the surplus slurry that flies to the upper inside of the recovery equipment will bounce back into the front panel and cause unevenness. If the difference between the excess slurry discharge angle and the swing-off angle is too large, the phosphor particles are likely to be scattered on the inner surface of the front panel when returning to the swing-off angle, and unevenness is likely to occur. This angle difference is not less than 5 ° and not more than 20 °, preferably not more than 15 °.
[0033]
As described above, the front panel on which the phosphor screen surface is formed is joined to a funnel, an electron gun is incorporated, and finally a cathode ray tube is completed through other processes.
[0034]
【The invention's effect】
As described above, according to the present invention, even if the inner surface of the front panel approaches a flat surface, after the surplus slurry is discharged, the process proceeds to the swing-off step while minimizing the upward lifting of the phosphor particles due to gravity. It is possible to suppress the unevenness due to the remaining surplus slurry and the dropping of the phosphor particles at the same time. And the color cathode ray tube manufactured by this invention can maintain favorable white quality.
[Brief description of the drawings]
FIG. 1 is a diagram showing a change in the inclination angle of a front panel in the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a front panel showing a state of filling phosphor particles in the first embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a front panel showing a state of filling phosphor particles according to a second embodiment of the present invention. FIG. 4 is a partially cutaway perspective view of a general color cathode ray tube apparatus. FIG. 6 is a cross-sectional schematic diagram of a front panel showing a state of filling with phosphor particles according to the prior art. FIG. 7 is a front panel showing a state of filling with phosphor particles according to the prior art. Cross-sectional schematic diagram [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Front panel 2 Phosphor slurry 3 1st color phosphor particle 4 2nd color phosphor particle 5 3rd color phosphor particle

Claims (3)

A color cathode ray for forming a desired phosphor screen on the inner surface of the front panel by repeating the step of forming a phosphor stripe pattern on the inner surface of the front panel at least twice while changing the tilt angle and rotation speed of the front panel. A method of manufacturing a tube,
When forming phosphor stripe patterns for the second and subsequent colors,
An application step of spreading phosphor slurry on the inner surface of the front panel by setting the inclination angle of the front panel to less than 90 ° and rotating the front panel around its central axis at a predetermined rotation speed;
Subsequently, the inclination angle of the front panel is 105 ° or more and 130 ° or less , the front panel inner surface is vertically inclined downward, and the front panel is rotated around its central axis at a predetermined rotation speed, A discharge step of discharging the surplus of the phosphor slurry vertically downward from the inner surface of the front panel;
Then, the inclination angle of the front panel with to return to an angle exceeding the angle less at and 90 ° than the inclination angle in the discharge step, the central axis of the front panel from the rotational speed at a high rotational speed in the discharging process By rotating around, further discharging the surplus of the phosphor slurry, and making the thickness of the phosphor slurry film on the inner surface of the front panel uniform,
A method for producing a color cathode ray tube, comprising: The method for manufacturing a color cathode ray tube according to claim 1, wherein an inclination angle of the front panel in the swing-off step is 95 ° or more. The manufacturing method of the color cathode ray tube according to claim 1 or 2 , wherein a difference between the inclination angle of the front panel is 5 ° or more and 20 ° or less between the discharge step and the swing-off step.

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