JPS63116779A - Method for applying phosphor slurry - Google Patents

Abstract

PURPOSE:To prevent the generation of grains on a coating film, by providing a filter device to the piping on the nozzle feed-in side of a phosphor slurry and respectively providing three-way solenoid valves to the outlet and inlet of the filter device and successively performing the discharge of the residual slurry of a desired piping part, the backwashing of the piping part and the evacuation thereof. CONSTITUTION:The three-way solenoid valve 1 on the inlet side of a filter device 2 and the three-way solenoid valve 3 on the outlet side thereof are respectively operated by a control apparatus 4 so that a head tank is connected to an injection solenoid valve to perform phosphor slurry coating work. At this time, the foreign matter or phosphor aggregate mixed with the injection slurry is separated and removed by the mesh filter 10 of the filter device 2. At the point of time when slurry injection work over a set time is finished, two three- way solenoid valves 1, 3 are operated to block the piping part containing the filter device 2. The discharge of the residual slurry, backwashing due to the injection of pure water and the evacuation of piping are successively performed with respect to said blocked piping part.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention uses an automatic coating device to apply phosphor to form a phosphor screen on the inner surface of a glass panel constituting a color cathode 8i ray tube or a display cathode ray tube. The present invention relates to a phosphor slurry coating method for coating the inner surface of the glass panel.

[Prior Art] Generally, Color I! The fluorescent screen of the triode is made of a photosensitive binder, such as polyvinyl alcohol (hereinafter referred to as PVA).
A phosphor slurry in which a specified phosphor is suspended in a solution containing modified ammonium chromate as the main component is applied to the inner surface of the glass panel, and after dry explosion, it is exposed to light through a shadow mask as a color selection electrode using an exposure device. A latent image is formed, and then developed to form phosphor stripes or phosphor dots (hereinafter collectively referred to as phosphor stripes) of a predetermined size at desired positions.

This process is performed on three types of phosphor slurries: green, blue, and red, thereby forming three types of phosphor stripes at positions corresponding to the openings of the shadow mask.

Since the phosphor slurry used to form the phosphor screen is expensive,
The excess amount in the coating process is collected, the required composition is adjusted, and the slurry is used again as a slurry for forming a phosphor screen. FIG. 2 shows the flow of supplying and recovering this phosphor slurry.

In FIG. 2, (21) is the phosphor slurry injection step, (
22) is the phosphor slurry recovery process, (23) is the drying and trimming process to remove the phosphor slurry from the panel skirt, (24) is the pump, (25) is the slurry tank for injection, and (26) is the replenishment slurry. It's a tank.

As shown by the dotted line in FIG. 2, the phosphor slurry is supplied from the injection slurry tank (25) to the injection step (21) by a pump (24), and the excess slurry is sent to the recovery step (22).
) and returned to the injection slurry tank (25).

Normally, the phosphor screen of a color cathode tube is formed by sequentially moving a carrier to which a glass panel is fixed through the above-mentioned manufacturing process lined in a loop at a predetermined cycle time.
It is manufactured by so-called automatic machines.

To apply the phosphor slurry in the phosphor screen coating process,
As shown in FIG. 3(a), the glass panel (33) is held in a carrier (34), and while this carrier (34) is rotated, the solenoid valve (33) connected to the pump (24) in FIG. 36) is used to inject the phosphor slurry (35) into a predetermined position of the glass panel (33), the phosphor slurry (35) spreads over the inner surface of the glass panel (33) to form a uniform coating surface. be done.

In this case, if the inclination and rotation speed of the carrier (34) are selected appropriately, the skirt portion (3
The phosphor slurry (35) is spread over the entire surface except for 7).

After applying the phosphor slurry (35) in this way and proceeding to the above-mentioned steps in sequence, green, blue, and red fluorescent light is formed on the inner surface of the glass panel (33), respectively, as shown in FIG. 3(b). Body stripes (30), (:II), (32) are formed.

Next, the main parts of a conventional automatic phosphor slurry coating device used to carry out the phosphor screen forming process shown in FIG. 2 will be explained with reference to FIG. 4.

The liquid level control device (41) is installed in the slurry tank (25) for injection.
) is provided, and the phosphor slurry (
The slurry (41) (hereinafter referred to as injection slurry) is supplied under pressure to the head tank (42) using, for example, a tire plum pump (24). The liquid level of this head tank (42) is kept at a constant level by the overflow pipe (43), and the liquid level of this head tank (42) is maintained at a constant level by the overflow pipe (43).
44) is connected to the electromagnetic valve (36), and the injection slurry (35) is applied with a constant head pressure from the nozzle (45) of the electromagnetic valve (36) to the inner surface of the glass panel (33) as described above for a certain period of time. It is designed to be injected. When the slurry (35) does not need to be injected, the solenoid valve (36) is activated to connect the return pipe (45) to the slurry tank for injecting (45).
A circulation system is formed in which the slurry is refluxed to the slurry tank (25) through a filtration device 21 (46), which is, for example, a mesh filter made of stainless steel and is attached to the slurry tank (25).

The circulation system is provided with a device for recovering excess of the injection slurry (35) injected into the inner surface of the glass panel (33). That is, by rotating the glass panel (33) at high speed in the collection container (47) movable in the x direction in FIG. The collected excess slurry is passed through the collection pipe (48) to the filtration device (46).
The slurry tank (25) is configured to be returned to the injection slurry tank (25) through the injection slurry tank (25).

Since the amount of slurry recovered in this way is smaller than the amount of slurry injected, an amount of replenishment slurry (49) or a replenishment slurry tank (26) corresponding to the difference is supplied to the liquid level control device ( It is replenished via a replenishment pipe (50) equipped with a replenishment electromagnetic valve (51) that operates in response to a control signal from 4I). In this case, the composition of the replenishment field slurry (49) is set to be an M1 component that compensates for the change in composition of the slurry recovered as described above, that is, the decrease in the phosphor content and the increase in the PVA content.

A predetermined thickness of phosphor slurry is applied to the inner surface of the glass panel (33) using the automatic phosphor slurry coating device as described above, and the process proceeds to the next dry trimming step (23) as shown in Figure 2. . In this dry trimming step (23), the phosphor slurry film (25) is dried and the phosphor slurry film (25) that has spread on the four corners of the glass panel (33) and a part of the inner surface of the skirt part is cleaned with pure water. Wash it off.

After dry explosion, the exposure and development process (27) is shown in Figure 2.
After that, phosphor stripes are formed.

[Problem to be solved by the invention 1 According to the conventional method described above, the glass panel (33
) as shown in Fig. 5 (hereinafter referred to as the stripe theory) (53), and even without removing the stripes, there may be spot-like brightness unevenness in the finished tube ( 54), which has a negative effect on the yield of the manufacturing process and the quality of the finished pipe.

The main causes of such defects are slurry application,
In other words, when the slurry is injected into the inner surface of the glass panel (33), the injected slurry contains foreign matter or phosphor aggregates that cause local defects. Defects caused by these foreign substances and aggregates are usually called "bubbles."

Conventionally, in order to eliminate this bulge, attempts have been made to attach a stainless steel mesh filter to the nozzle for injecting the slurry, or to devise a filtration device attached to the slurry tank for injection. However, in the former case, since a mesh filter is set inside the nozzle, the filtration area is small, and the filter becomes clogged in a short period of time, causing the amount of slurry injected to exceed the set amount. There was a problem that the slurry decreased over time and did not spread sufficiently to the inner surface of the glass panel (33), causing a defective situation. In addition, as a countermeasure to this problem, if the degree of filtration of the filter is improved, that is, if the mesh is made larger, the removal of the globules becomes insufficient. On the other hand, in the latter case, although the filtration area can be relatively large,
Again, there is a problem in that the filter becomes clogged over time and overflow decreases, resulting in a state in which sufficient filtration cannot be performed.

This invention was made to solve the above-mentioned problems, and it improves the quality of cathode ray tube phosphor screens by eliminating lumps and eliminating the need for manual labor and without causing secondary defects. It is an object of the present invention to provide a method for applying a phosphor slurry that can improve manufacturing yield.

[Means for Solving the Problems] The phosphor slurry coating method according to the present invention includes providing a filtration device in the middle of the pipe on which the phosphor slurry is sent to the nozzle, and installing filters on the inlet and outlet sides of the filtration device. A 3-way solenoid valve is provided for each, and by operating these 3-way solenoid valves as necessary, a portion of the phosphor slurry feed-in piping is shut off, and residual slurry is discharged and backwashed from the shut-off piping section. , is characterized in that vacuuming is performed sequentially.

[Function] According to the present invention, during the automatic application of phosphor slurry by an automatic phosphor slurry coating device, during the slurry injection step of injecting the injection slurry into the inner surface of the glass panel through the nozzle, the injection slurry Foreign matter and fluorescent substance aggregates mixed therein are separated and removed by the above-mentioned filtration device.

When the above-described slurry injection operation for a set period of time is completed, the two three-way solenoid valves (1) are operated to shut off the piping section including the filtration device.

In this cut-off IS, by sequentially discharging the residual slurry, injecting pure water into the cut-off piping section, and evacuating the inside of the pipe, the foreign matter and phosphor aggregates separated and removed by the above-mentioned filtration device are removed. At the same time, moisture remaining in the cut-off piping portion during washing is also discharged outside the piping to prevent the residual moisture from foaming due to air in the piping.

Thereafter, by returning to the slurry injection process, it is possible to prevent the formation of lumps due to the foreign matter or phosphor aggregates being mixed into the slurry.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 shows a cross-sectional view of the main parts of an automatic phosphor slurry coating device used in carrying out a phosphor slurry coating method according to an embodiment of the present invention, and a conventional phosphor slurry coating device shown in FIG. 4. The difference from the automatic coating device is that the nozzle (45) is attached to the three sides mentioned above. l! A variable backwash type filtration device is provided in the middle of the piping (44) that feeds the injection slurry (35) to the magnetic valve (36).

In Figure 1, (2) is a mesh filter (10)
(1), (3)
) are 3-way solenoid valves installed on the inlet and outlet sides of the filtration device (2), and connected to the head via the 3-way solenoid valve (1) on the inlet side or the piping (44A). It is connected to the tank (42) and also has a three-way solenoid valve (
3) is connected to the above three-way injection solenoid valve (36) via piping (44B).

(5) and (6) are three-way solenoid valves interposed in the middle of the pipes (44a) and (44b) branch-connected to the three-way solenoid valves (1) and (3), and are located on the inlet side. 3-way solenoid valve (5
) is connected to the injection slurry tank (25) via piping (45a).
) and the 3-way solenoid valve (1) via the piping (46a), and is connected to the 3-way solenoid valve (6) on the outlet side or the piping (
45b) to the atmosphere open type solenoid valve (7) and piping (4
6b) to a pure water supply solenoid valve (8). Also, one side of the three-way solenoid valve (If) is connected to a pipe (47
a) Vacuum pump (1G) via trap (1G)
5), and the remaining one is open to the outside via the piping (48a), and the piping (46b)
Clean air is supplied to the piping (47b) branched from the pipe (47b) via a solenoid valve (12) and an air filter (17).
m valve (13) is connected.

(4) is a control device, each of the above-mentioned solenoid valves (1), (
3), (59, (6), (7), (8), (II), (
12), (1:l) and vacuum pump (15) are operated in a set order.

Next, a method of applying phosphor slurry to the inner surface of the glass panel (33) using an automatic phosphor slurry coating apparatus equipped with an automatic backwash type filter bag as described above will be described.

First, the control device (4) controls the three-way solenoid valve (1) on the inlet side of the filtration device (2) and the three-way solenoid valve (3) on the outlet side.
) are respectively connected to the head tank (42) and the injection solenoid valve (36), and the injection slurry (35) in the head tank (42) is passed through the pipe (44) to the three-way solenoid valve. The noise (45) of (36) is injected into the inner surface of the glass panel (33) at a constant head pressure for a certain period of time, and the phosphor slurry coating operation as described above is performed. At this time, the mesh filter (10) of the filtration device (2) separates and removes foreign matter and fluorescent substance aggregates mixed into the injection slurry (35).

When the above phosphor slurry application operation continues for a certain period of time, the two 3-way AM valves (+) and (3) are activated in response to a command signal from the control device (4).
]), (') The piping section including the filtration device (2) is shut off.At this time, the three-way solenoid valves (5) and (6) are simultaneously opened and the solenoid valve (7) is opened to the atmosphere. Filtration device (
2) and the slurry remaining in the shutoff piping section flows down by gravity into the injection slurry tank (25) via the three-way solenoid valve (5), piping (44a), and piping (45a) and is collected.

Next, the piping (44a) and the piping (46a) are connected by switching the three-way solenoid valve (5), and
By switching the 3-way solenoid valve (6), the pipe (44b) and the pipe (46b) are connected, and at the same time, the 3-way FL solenoid valve (1) is connected.
1) The above piping (46a) and piping (48a)
and open the solenoid valve (8). In this state, pure water of approximately 3 g/r, rm is injected from the open end of the solenoid valve (8) to backwash the mesh filter (10) in the filtration device (2). The purified water for cleaning is sent to the piping (4
4a) → 3-way solenoid valve (5) → piping (46a) + 3-way solenoid valve (11) → piping (48a) before being discharged to the outside.

Then, the solenoid valve (8) is closed, and the solenoid valves (12) and (13) are opened. In this state, lean air is passed from the open end of the TL81 valve (13) to the air filter (
17), the water in the cut-off piping section including the filtration device (2) is discharged to the outside through the same route as the above-mentioned cleaning pure water.

After that, the above-mentioned solenoid valves (12) and (13) are closed to complete airtightness of the upper part, and then the above-mentioned 3-way solenoid valve (11) is closed.
The switching operation connects the pipe (46a) and the pipe (47a). In this state, the vacuum pump (15) is operated to evacuate the interior of the cutoff piping section. When this vacuuming progresses, the three-way solenoid valves (1), (]) are returned to the normal phosphor slurry working state.

Although the above example shows the case where green phosphor slurry is injected and applied to the inner surface of a 19 to 25 inch color cathode ray tube, it is also possible to inject and apply red or blue phosphor slurry to the inner surface of a 19- to 25-inch color cathode ray tube. It may also be applied to injection application of phosphor slurry to the inner surface of the tube.

[Effects of the Invention] As described above, according to the present invention, foreign matter and phosphor aggregates mixed in the phosphor slurry are separated and removed by a filtration device in the middle of the piping immediately before injection of the phosphor slurry, and The separated and removed foreign matter and phosphor aggregates can be reliably discharged from the piping by backwashing, which eliminates the occurrence of lumps in the slurry coating film and eliminates deterioration in the quality of the phosphor screen due to stripes and uneven brightness. As a result, manufacturing yield and quality can be improved. Furthermore, after backwashing, a portion of the shutoff piping used during backwashing can be evacuated, so there is no occurrence of secondary defects such as the generation of bubbles due to residual moisture.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main parts of an apparatus used to carry out a method for applying phosphor slurry according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the manufacturing process such as supplying and recovering phosphor slurry.
FIG. 3(a) is a sectional view of the main parts of a coating device applied to the phosphor slurry coating method, FIG. 3(b) is a sectional view showing the main structure of a glass panel, and FIG. 4 is a sectional view of a conventional fluorescent coating device. FIG. 5 is a block diagram of an automatic phosphor slurry coating apparatus used in the body slurry coating method, and is a sketch diagram showing a defect occurring on a glass panel phosphor screen, a portion of which is enlarged and shown. (1), (3), (:11i)...3-way solenoid valve, (2
)...filtration device, (4)--control device, (15)-
... Vacuum pump, (25) ... Slurry tank for injection,
(:l:I)...Glass panel, (35)...phosphor slurry, (45)...nozzle. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (2)

[Claims] (1) An injection slurry tank for storing phosphor slurry, a nozzle for injecting phosphor slurry into the inner surface of the cathode ray tube glass panel, a state for feeding the phosphor slurry in the tank to the nozzle, and a state immediately before the nozzle. In the method for applying phosphor slurry using an automatic phosphor slurry coating device, the phosphor slurry automatic coating device is equipped with a phosphor slurry forced liquid feeding piping system having a three-way solenoid valve that can be switched to a state where the phosphor slurry is branched at a point and then returned to the tank. A filtration device is installed in the middle of the piping on the side that sends the phosphor slurry to the 3-way solenoid valve, and a 3-way solenoid valve is installed on each of the inlet and outlet sides of this filtration device. The phosphor slurry is characterized in that when the phosphor slurry is activated, a part of the pipe on the feeding side of the phosphor slurry is cut off, the residual slurry in the cut-off pipe part is discharged, the filtration device is backwashed, and the filtration device is evacuated. How to apply. (2) The phosphor slurry coating method according to claim 1, wherein the filtration device is configured to keep the mesh filter in a substantially horizontal position with the phosphor slurry inlet side at the bottom.