JP2004319184A - Fluorescent film forming method and cathode-ray tube using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescent film forming method by which it is possible to form a uniform fluorescent film which assures no falling of a fluorescent material even if a curvature of the inner face of a panel becomes small. <P>SOLUTION: This fluorescent film forming method includes a process of injecting and spreading a phosphor material slurry to the inner face of the panel, a process of discharging redundant liquid of the slurry in order to homogenize the film thickness of the phosphor slurry spread on the inner face of the panel, and a process of drying the phosphor slurry in which the excess liquid is discharged, and in the process of drying, the phosphor slurry is dried by rotating the panel at a revolution number of 6 rpm or more and 10 rpm or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for forming a fluorescent screen used in a cathode ray tube such as a color cathode ray tube and a cathode ray tube using the same.
[0002]
[Prior art]
FIG. 4 is a partial cross-sectional perspective view showing the configuration of a general cathode ray tube, and FIG. 5 is a perspective view showing the configuration of a general fluorescent screen provided on the cathode ray tube.
[0003]
The cathode ray tube includes a glass envelope including the panel 1, a funnel portion 91 and a neck portion 92, an electron gun 93 sealed in the neck portion 92, and a deflection yoke for deflecting an electron beam 94 radiated from the electron gun 93. 95, a fluorescent screen 96, a color selection electrode 97 arranged at a predetermined distance from the fluorescent screen 96 on the electron gun 93 side, and a magnetic shield 98.
[0004]
FIG. 6A is a cross-sectional view showing the state of filling the phosphor particles of the second color after shaking-off drying in the conventional phosphor film forming method, and FIG. 6B is a diagram showing the filling state of the phosphor particles of the second color after completion. It is sectional drawing which shows a state.
[0005]
As shown in FIGS. 5 and 6A, a black film 99 is formed at a predetermined position on the inner surface of the panel 1, and red, green, and blue fluorescent film patterns 100 are formed thereon at predetermined positions. It is formed by forming a reflective film 101 of aluminum or the like thereon. The fluorescent film of each color emits light when irradiated with the electron beam 94 that reaches through the color selection electrode 97.
[0006]
Generally, a slurry method is used as a method for manufacturing a fluorescent screen of a color cathode ray tube. In this slurry method, a slurry in which phosphor powder is suspended in a photoresist obtained by adding an aqueous solution of ammonium bichromate (ADC) to an aqueous solution of polyvinyl alcohol (PVA) is inclined at a predetermined angle with the inner surface of panel 1 facing upward. Then, slowly rotate and inject, and then slowly spread the coating. After the slurry has spread over the entire inner surface of the panel 1, the panel is tilted and rotated at a high speed to discharge the excess slurry. A film is formed, and the fluorescent film is dried by a heater, warm air or the like. Next, the color selection electrode 97 is mounted at a predetermined position on the inner surface of the panel 1, exposed, and developed with warm water or the like to form a fluorescent film pattern of a predetermined color.
[0007]
This process is sequentially performed on 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-deposited film is formed thereon to manufacture a fluorescent screen of a color CRT.
[0008]
One of the important items in the method of manufacturing the phosphor screen is to make the phosphor film thickness uniform. When the thickness of the fluorescent film is not uniform, the amount of light emitted from the phosphor is not uniform, and there is a problem that unevenness of brightness and darkness occurs on a screen. In addition, if a film thickness difference and a resulting luminance difference occur depending on the panel position for each of the three colors, there is a problem that the white color quality is significantly impaired because the luminance ratio of the three colors differs depending on the panel position.
[0009]
As a technique for solving such a problem, for example, Japanese Patent Application Laid-Open No. Sho 54-69058 discloses that the number of rotations of the panel in the drying step is made slower than the high-speed rotation so as to make the thickness of the phosphor uniform. Have been.
[0010]
[Patent Document 1]
JP-A-54-69058
[Problems to be solved by the invention]
However, in the above technique, when the phosphor is dried and fixed at a certain rotation speed or more, the phosphor particles move by the action of centrifugal force due to the rotation of the panel. As a result, in the case of the phosphor film formed in the second color, as shown in FIGS. 6A and 6B, the filling ratio of the phosphor outside the phosphor 3 in the first color with respect to the center of the panel 1 is high. The filling ratio of the phosphor inside the phosphor 3 of the first color with respect to the center of the panel 1 becomes low. As a result, the filling rate of the phosphor 4 of the second color differs between the left and right sides of the screen, resulting in an uneven film thickness.
[0012]
FIG. 7A is a cross-sectional view showing a state of filling the phosphor particles of the third color after shaking-off drying in the conventional phosphor film forming method, and FIG. 7B is a diagram showing the filling state of the phosphor particles of the third color after completion. It is sectional drawing which shows a state.
[0013]
In the case of the phosphor 5 formed in the third color, the direction of the groove formed by the pattern of the phosphor films 3 and 4 of the first color and the second color coincides with the direction of the centrifugal force applied to the phosphor, particularly from the center of the panel 1. In the region above and below the phosphor, the filling factor of the phosphor is remarkably reduced, resulting in an uneven film thickness. In particular, the smaller the curvature of the inner surface of the panel 1 is, the smaller the component of the centrifugal force of the rotation of the panel in which the phosphor particles are suppressed by the inner surface of the panel 1 is, so this tendency becomes more remarkable.
[0014]
An object of the present invention is to provide a method for forming a fluorescent film and a cathode ray tube using the same, which can form a uniform fluorescent film without a phosphor falling off even if the curvature of the inner surface of the panel becomes small.
[0015]
[Means for Solving the Problems]
The phosphor film forming method according to the present invention is a phosphor film forming method of forming a phosphor film on an inner surface of a panel provided in a cathode ray tube, wherein a step of injecting and spreading a phosphor slurry on the inner surface of the panel, A step of discharging an excess liquid of the phosphor slurry in order to make the thickness of the phosphor slurry spread on the inner surface of the panel uniform, and a step of drying the phosphor slurry from which the excess liquid has been discharged. The drying step includes drying the phosphor slurry while rotating the panel at a rotation speed of 6 rpm or more and 10 rpm or less.
[0016]
A cathode ray tube according to the present invention includes a panel having a phosphor film formed on an inner surface by the phosphor film forming method according to the present invention.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
In the phosphor film forming method according to the present embodiment, the phosphor slurry is dried while rotating the panel at a rotation speed of 6 rpm or more and 10 rpm or less. Therefore, the movement of the phosphor due to the influence of the centrifugal force can be minimized. As a result, the thickness of the phosphor formed on the inner surface of the panel can be made uniform.
[0018]
In this embodiment, in the drying step, it is preferable that the panel is rotated at a rotation speed of 6 rpm or more and 10 rpm or less until the fixation of the phosphor starts. Here, "until the fixation of the phosphor starts" refers to a point in time at which at least a part of the phosphor film starts to fix after the drying of the phosphor film is started. When the fixation of the phosphor film starts, the surface of the portion starts discoloring, and can be visually confirmed. Thereafter, even if the rotation speed of the panel is increased, the movement of the phosphor due to the centrifugal force can be suppressed.
[0019]
The phosphor film is sequentially formed on three color phosphor films, and in the drying step, the panel may be rotated at a rotation speed of 6 rpm or more and 10 rpm or less when the second or third color phosphor film is formed. preferable.
[0020]
It is preferable that the inner surface has a radius of curvature of 10,000 millimeters (mm) or less.
[0021]
In the drying step, the phosphor slurry is preferably dried by a heater and warm air.
[0022]
Preferably, in the spreading step, the phosphor slurry is injected while rotating the panel at a rotation speed of 15 rpm or more.
[0023]
In the step of discharging the surplus liquid, it is preferable to discharge the surplus liquid while rotating the panel at a rotation speed of 100 rpm or more.
[0024]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0025]
FIG. 1A is a cross-sectional view showing the filling state of the second color phosphor particles after shaking-off drying in the phosphor film forming method according to the present embodiment, and FIG. 1B is a sectional view of the second color phosphor particles. It is sectional drawing which shows the filling state after completion.
[0026]
The panel 1 has an outer diameter of 500 millimeters (mm) × 700 millimeters (mm), and the inner surface has a radius of curvature of about 10,000 millimeters (mm).
[0027]
The phosphor slurry to be injected is obtained by suspending about 30% of a red phosphor powder in a photoresist obtained by adding an aqueous solution of ammonium bichromate (ADC) to an aqueous solution of polyvinyl alcohol (PVA). The angle of inclination of the panel 1 is 0 ° when the inner surface is vertically upward, and the angle between an axis perpendicular to the panel face and the vertical axis is indicated as θ. In this embodiment, the fluorescent film is formed in the order of green, blue, and red.
[0028]
In the panel after the formation of the stripe pattern of the green phosphor of the first color, 200 ml (ml) of blue phosphor slurry is injected at a rotation speed of the panel 1 of 15 rpm with the panel inclination angle θ being 14 °. . Thereafter, the panel 1 is held at a low rotation of 6 rpm for 40 seconds, and the phosphor slurry is spread over the entire inner surface of the panel 1.
[0029]
Then, while the panel 1 is quickly tilted to 110 degrees to discharge the excess liquid, the panel 1 is rotated at 150 rpm for 20 seconds to uniformize the film thickness by shaking off and further discharge the excess liquid. Next, while the rotation speed of the panel 1 is maintained at 8 rpm, a coating process is completed through a process of drying with a heater and warm air for 200 seconds, and a phosphor film is completed through an exposure and development process.
[0030]
FIGS. 6A and 6B show the degree of filling of the phosphor particles at the end of the coating step when the panel rotation speed in the drying step is 12 rpm or more, and FIG. FIG. 1B shows the degree of filling of the phosphor particles at the end of the application step in the case where the present embodiment is performed.
[0031]
In the conventional example shown in FIGS. 6A and 6B, a force to move the phosphor particles acts due to the centrifugal force during the drying rotation. At this time, the second color phosphor film 4 deposited between the first color phosphor stripes 3 moves to the outside of the first color phosphor stripe 3 with respect to the center of the panel 1 under the influence of the centrifugal force. .
[0032]
For this reason, a large difference in the phosphor filling ratio (phosphor film thickness) occurs between the outside and the inside of the phosphor stripe 3 of the first color. The non-uniform distribution of the filling ratio of the color fluorescent film 4 is different.
[0033]
On the other hand, when the drying rotation speed is set to 10 rpm or less as in the present embodiment, the difference in the phosphor filling ratio between the outside and the inside of the first color phosphor stripe 3 with respect to the panel center is greatly reduced. The difference was almost eliminated when the drying rotation speed was set to 8 rpm or less. Further, when the drying rotation speed was set to 6 rpm or less, unevenness occurred due to the excess slurry of the panel skirt returning to the inner surface of the panel 1.
[0034]
FIG. 2 is a graph showing the relationship between the panel rotation speed during drying and the thickness of the phosphor of the second color in the phosphor film forming method according to the present embodiment. In the prior art, the filling rate of the blue phosphor film 4 of the second color is a non-uniform distribution in which the filling rate decreases on the left side of the screen and the filling rate improves on the right side of the screen due to the stripe arrangement, and the white quality is yellowish on the left side of the screen. It became white and cyan white on the right side of the screen. By setting the drying rotation speed to 6 rpm or more and 10 rpm or less as in the present embodiment, the problem of the white quality described above was solved.
[0035]
As described above, according to the present embodiment, the phosphor slurry is dried while rotating panel 1 at a rotation speed of 6 rpm or more and 10 rpm or less. Therefore, the movement of the phosphor due to the influence of the centrifugal force can be minimized. As a result, the thickness of the phosphor formed on the inner surface of panel 1 can be made uniform.
[0036]
Next, a case where the red phosphor stripe 5 of the third color is formed on the panel on which the stripe pattern of the second color is formed will be described. FIG. 3A is a cross-sectional view showing the filling state of the phosphor particles of the third color after shaking-off drying in the phosphor film forming method according to the present embodiment, and FIG. 3B is a sectional view of the phosphor particles of the third color. It is sectional drawing which shows the filling state after completion.
[0037]
If the panel rotation speed in the phosphor drying step for the third color is more than 10 rpm, a force to radially move the phosphor particles in the radial direction due to centrifugal force acts. At this time, the movement of the phosphor particles 5 of the third color deposited between the phosphor stripe 3 of the first color and the phosphor stripe 4 of the second color is restricted in a direction perpendicular to the phosphor stripe. The movement is not restricted in the direction parallel to.
[0038]
At the same radial distance from the panel center, the force applied in the parallel direction increases as the stripe portion approaches the center. As a result, the movement of the particles increases in the stripe portion closer to the center, and the filling degree decreases.
[0039]
On the other hand, if the drying is performed at a panel rotation speed of 10 rpm or less, the movement of the phosphor particles 5 of the third color due to the centrifugal force described above becomes difficult to occur, and the phosphor filling of the stripe portion near the center is performed. It was possible to suppress the rate from decreasing.
[0040]
Further, as in the case of the above-described embodiment, the lower the number of drying rotations, the more the reduction in the phosphor filling rate can be suppressed. Unevenness due to the excess slurry returning to the inner surface of panel 1 occurred.
[0041]
In the prior art, the filling rate of the third color red phosphor 5 is reduced in the region above and below the center of the screen, and the white quality is cyan white from the center of the screen to the region above and below. By performing the above embodiment, this problem of white quality was solved.
[0042]
As described above, according to the present embodiment, even when the curvature of the inner surface of the panel is reduced, the movement of the particles due to the centrifugal force is suppressed by using the panel rotation speed of 6 rpm or more and 10 rpm or less in the phosphor drying step. Thus, it was possible to provide a method for obtaining an effect of making the filling rate of the phosphor film uniform, and it was possible to maintain good white quality.
[0043]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a phosphor film forming method capable of forming a uniform phosphor film without dropping of the phosphor even when the curvature of the inner surface of the panel is reduced, and a cathode ray tube using the same. be able to.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view showing a filling state of phosphor particles of a second color after shaking-off drying in a phosphor film forming method according to the present embodiment;
(B) is a cross-sectional view showing a filled state after completion of the second color phosphor particles.
FIG. 2 is a graph showing a relationship between a panel rotation speed during drying and a film thickness of a second color phosphor in the phosphor film forming method according to the present embodiment.
FIG. 3A is a cross-sectional view illustrating a filling state of phosphor particles of a third color after shaking-off drying in the phosphor film forming method according to the present embodiment;
(B) is a cross-sectional view showing a filled state after completion of the phosphor particles of the third color.
FIG. 4 is a partially sectional perspective view showing a configuration of a general cathode ray tube.
FIG. 5 is a perspective view showing a configuration of a general fluorescent screen provided in a cathode ray tube.
FIG. 6 (a) is a cross-sectional view showing a filling state of phosphor particles of the second color after shaking-off drying in a conventional phosphor film forming method,
(B) is a cross-sectional view showing a filled state after completion of the second color phosphor particles.
FIG. 7A is a cross-sectional view showing a filling state of phosphor particles of a third color after shaking-off drying in a conventional phosphor film forming method,
(B) is a cross-sectional view showing a filled state after completion of the phosphor particles of the third color.
[Explanation of symbols]
1 Panel 3 First color phosphor particles and stripes 4 Second color phosphor particles and stripes 5 Third color phosphor particles and stripes 91 Funnel 92 Neck 93 Electron gun 94 Electron beam 95 Deflection yoke 96 Phosphor screen 97 Color selection Electrode 98 Magnetic shield 99 Black film 100 Fluorescent film pattern 101 Reflective film

Claims (5)

A phosphor film forming method for forming a phosphor film on an inner surface of a panel provided in a cathode ray tube,
A step of injecting and spreading a phosphor slurry on the inner surface of the panel,
Discharging a surplus liquid of the phosphor slurry to make the thickness of the phosphor slurry spread on the inner surface of the panel uniform,
Drying the phosphor slurry from which the excess liquid has been discharged,
The method of forming a fluorescent film, wherein the drying includes drying the phosphor slurry while rotating the panel at a rotation speed of 6 rpm or more and 10 rpm or less. The method of forming a fluorescent film according to claim 1, wherein in the drying step, the panel is rotated at a rotation speed of 6 rpm or more and 10 rpm or less until the fixing of the phosphor starts. The fluorescent film is sequentially formed for three color fluorescent films,
2. The method of claim 1, wherein the drying includes rotating the panel at a rotation speed of 6 rpm or more and 10 rpm or less when forming a second or third color fluorescent film. 3. The phosphor film forming method according to claim 1, wherein an inner surface radius of curvature of the panel is 10000 millimeters (mm) or less. A cathode ray tube comprising a panel having a fluorescent film formed on an inner surface by the method for forming a fluorescent film according to claim 1.

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