JPS5947419B2 - Color picture tube fluorescent surface coating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluorescent surface coating device for a color picture tube.

Generally, the fluorescent surface of a color picture tube is constructed as follows.

That is, first, a photosensitive resin in which a phosphor is dispersed (hereinafter referred to as phosphor slurry) is applied to the inner surface of the face plate of the picture tube panel to form a phosphor film, and then a phosphor film is formed. The film is exposed to light passing through the striped or dot-shaped mask holes of the shadow mask, and only the areas corresponding to the mask holes are exposed and photocured, and this is developed to form a predetermined fluorescent film on the same areas. By repeating this operation for red, blue, and green phosphors, a striped or dot-shaped phosphor surface consisting of red, blue, and green phosphors can be obtained. I have to.

Normally, the brightness of the fluorescent surface formed on the inner surface of the face plate of a color picture tube panel, that is, the brightness of the screen when the fluorescent surface is excited by an electron beam and emitted light, is determined by the brightness of the formed fluorescent surface. In addition to the properties of the light surface, especially the luminescent properties and particle size of the phosphor that forms the phosphor film, it is also affected by the thickness of the phosphor film. It is said that the thicker it is, the brighter it is.

On the other hand, however, as the fluorescent film that is formed on the inner surface of the face plate by photocuring by exposure to light as described above becomes thicker, the fluorescent film becomes less fluorescent due to attenuation of light within the film. The photochemical reaction on the face plate side of the film becomes difficult to occur, and as a result, photocuring in this area becomes insufficient, and the fluorescent film tends to peel off during the development process. will occur.

Therefore, in order to obtain a uniform and bright fluorescent surface on a color picture tube, it is necessary to form the fluorescent film uniformly and thickly within a range that does not cause the ``drop'' phenomenon.

The conventional method of coating the inner surface of the face plate with a phosphor slurry and drying it to form a phosphor surface as described above uses a coating device that performs an indexing motion to apply the phosphor slurry onto the inner surface of the face plate of the picture tube panel. After injection, the panel is swung at high speed to shake off excess phosphor slurry to the surrounding area to obtain a constant film thickness, and the shaken phosphor slurry is caught in a saucer. In particular, the slurry is recovered and reused, but the recovered slurry has a lower concentration of phosphor than the slurry to be coated.

Therefore, in the conventional means, in order to make the phosphor concentration of the slurry to be applied constant, a slurry with a high phosphor concentration is prepared in advance, and this is added to the stock solution at a predetermined ratio to compensate for the shortage of the recovered slurry. It is used mixed in the phosphor slurry.

In other words, the liquid level in a so-called dispenser, which is a stock solution container with a stirrer and a pump for coating slurry, is controlled, and the difference between the amount of slurry applied to the inner surface of the face plate and the amount of slurry collected is refilled. That's how I do it.

Furthermore, when a phosphor slurry is applied to the inner surface of the face plate to obtain a phosphor film as described above, the thickness of the phosphor film is determined by the amount of phosphor in the phosphor slurry if the coating process conditions are constant. From this point of view, the conventional method for forming a phosphor film requires the specific gravity of the phosphor (4 to 5.5) and the photosensitive material used to disperse it. Due to the speed of sedimentation of the phosphor due to the difference in specific gravity from the specific gravity of the fluorescent resin (approximately 1.0), the following points are needed to maintain a constant thickness of the applied phosphor film. It has the following drawbacks.

That is, one of them is when the phosphor slurry is injected by the coating device that performs the indexing movement described above.
Conventionally, in order to prevent sedimentation of the phosphor in the coating slurry, the coating slurry was constantly stirred by the dispenser and circulated under pressure through a predetermined piping system, and a three-way valve disposed in the piping system was used. The phosphor slurry is injected through the injection port by opening the valve for a predetermined period of time for each index, but even in this case, the distance between the valve seat of the three-way valve and the injection port is , during the pause period of each injection cycle, the applied slurry remains, and if the injection cycle is long, the phosphor will settle in this area, and the phosphor concentration will be high in that area at the beginning of the next injection. This phenomenon is particularly noticeable in slurries with high phosphor concentrations in order to obtain high-brightness color picture tubes. This causes density unevenness, and the above-mentioned ``drop'' phenomenon is observed in these partially thick film areas. Sedimentation of the phosphor in the coating slurry due to uneven coating cycles has been a problem.

Another problem is that when replenishing high-concentration phosphor slurry as described above, the added phosphor slurry naturally has a high specific gravity and settles quickly, so it is immediately pumped into the piping system. In addition, since the addition timing is determined by the operation command of the liquid level gauge, this highly concentrated slurry is directly injected into the panel, which is a foolish problem that tends to cause fluctuations in the overall film thickness. Furthermore, when panels of different dimensions are coated with the same indexing motion, the recovery rate from each panel is different, which causes variations in the phosphor concentration in the slurry even when the amount of slurry added is varied. Therefore, it is an object of the present invention to improve the above-mentioned drawbacks of the conventional method, to maintain a constant phosphor concentration in the slurry at all times, and to achieve a uniform phosphor concentration. An object of the present invention is to obtain a fluorescent surface coating device capable of obtaining a fluorescent film thickness, and in this invention,
To prevent sedimentation and separation of the phosphor that occurs when the injection cycle is long, empty discharge is performed even when there is no panel in order to maintain the regular injection cycle, and it is also necessary to maintain a constant concentration within the dispenser. For this purpose, an instruction to add syssurry is given based on a specific gravity signal from an attached hydrometer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fluorescent film coating apparatus according to the present invention will be described in detail below with reference to the accompanying drawings.

In the attached drawings, 1 is a dispenser for coating slurry; 2 is a dispenser for coating slurry;
3 is an injection valve (3-way valve) having an injection nozzle 4; 5 is a column supporting this 3-way valve 3 via a parallel link arm 6; 7 is a support for supporting the injection valve 3 above and below. An actuator for operation, 8 a cup 9 for receiving empty slurry, an arm supporting the cup 8;
10 is a rotary actuator for advancing and retracting the cup 8 to the injection position; 11 is a hydrometer attached to the dispenser 1; 12 is a control circuit that generates an additional output based on a signal detected by the hydrometer 11; 13; 14 is a dispenser 14 for high-concentration additional slurry; 15 is an addition valve for the additional slurry; 16 is a collection receiver; 17 is a moving panel chuck attached to a transport conveyor (not shown); In addition, a is a pipe forming a coating slurry circulation path, b is a pipe for empty slurry, C is a pipe for forming a recovery slurry recovery path, and d is a pipe forming a circulation path for additional slurry.

In the above configuration, in the dispensers 1 and 13, the respective motors 2 and 14 are operated to constantly stir the coating slurry contained in the dispenser 1, and the slurry is constantly stirred through the pipe a through the injection valve 3 for injection of the coating. The additional slurry which is circulated and contained in the dispenser 13 is likewise constantly stirred and is circulated through the additional valve 15 by line d.

Then, the panel A to be coated is attracted to the panel chuck 17 with the inner surface of the face plate facing upward, and is moved intermittently by the conveyor, stopping once at each position of the injection valve 3 and the collection receiver 16, and then changing the position of the panel A to the panel chuck 17. The movement of the fluorescent surface coating is performed by including the up and down movement at .

First, when the panel A approaches the application position, it is confirmed that the panel A is correctly held in the panel chuck 17, and the rotary actuator 10 is operated, and the receiver is moved to the cup 8.
is rotated and retracted from the injection nozzle 4 position to a predetermined position that does not obstruct the entry of panel A.

Panel A then rises to a predetermined position, and at the same time, the actuator 7 operates to lower the injection nozzle 4, and the injection valve 3 is opened to inject a predetermined amount of the coating slurry onto the inner surface of the face plate of panel A. After finishing, both panel A and injection nozzle 4 return to their original positions.

The panel A that has been injected in this way is then transferred to the next process, and in the next operation, it is rotated at high speed in the collection receiver 16 to shake off the excess coating slurry and turn it into a coating slurry. While obtaining a predetermined phosphor film by
The excess slurry that has been shaken off is collected by the collection receiver 16 and returned to the desvenser 1 again.

At this time, the receiver and the cup 8 have also returned to their regular positions below the injection nozzle 4.

By repeating this operation, the phosphor slurry is applied to the inner surface of the face plate of the panel A.

In this case, for example, if a panel A is missing from one of the panel chucks 17 due to the occurrence of a defect, the coating slurry cannot be injected from the injection nozzle 4 at the same position due to the missing panel.

Therefore, depending on the injection cycle at this time, an undesirable precipitation phenomenon of the phosphor occurs within the injection nozzle 4 and the injection valve 3.

In this case, in the present invention, the missing pulp A is detected and the injection is performed at this time into the receiving cup 8.
That is, by emptying, the regular injection cycle is maintained, and the coating slurry poured into the cup 8 is directly returned to the dispenser 1 and reused.

In this way, by injecting the coating slurry at a constant cycle regardless of the presence or absence of panel A, phosphor precipitation does not occur, and according to experiments, the same cycle can be maintained within 60 seconds. In particular, it was possible to almost eliminate the effects of selective phosphor precipitation.

Note that when the phosphor concentration of the coating slurry is increased, it is necessary to shorten the injection period, but for this purpose, the emptying operation for the bone cup 8 is performed each time immediately before injection into panel A. This can be dealt with by doing this.

Further, in order to keep the amount of phosphor in the coating slurry constant, the amount of phosphor in the slurry is directly proportional to the specific gravity of the slurry IJ-, and a specific gravity meter 11 attached to the dispenser 1 is used. The specific gravity is detected and the detection signal is used to replenish additional slurry.

That is, since the coating slurry is injected and the recovered slurry is returned by high-speed spinning, the dispenser 1
As the level of the coating slurry decreases, its specific gravity also decreases, and this specific gravity decrease signal causes the dispenser 1 to be additionally replenished with high-concentration phosphor slurry.

In this case, since the additional slurry has a high phosphor concentration and a high specific gravity, the sedimentation rate within the coating slurry is fast and the additional amount must not be immediately injected from the injection nozzle 4.

Therefore, after the coating slurry is injected, it is added from the addition valve 15 on average within a limited time in synchronization with the injection operation signal, and as a result, the high concentration slurry added is Since the mixture is thoroughly stirred before the next injection, good results can be obtained with little variation in specific gravity.

For example, with a conventional coating slurry with a specific gravity of 1.20 to 1.30, ±0.02? /cfl fluctuation, the method (7) shows a variation of ±0.001 to 0.002? It was possible to maintain an extremely high concentration of /cd.

By stabilizing the phosphor concentration in this way, other components in the coating slurry, such as the proportion of photosensitive resin in the slurry, are also stabilized, and properties such as photosensitivity and slurry viscosity are stabilized. This makes it possible.

As described in detail above, according to the present invention, a cup is placed to receive the empty slurry at the lower injection position of the injection nozzle of the coating reservoir, and when the panel is not at the same injection position within a predetermined period or when necessary Since the coating slurry can be emptied before injection into the next panel according to the situation, it is possible to prevent the coating slurry from accumulating in the injection nozzle and its three-way valve. In addition, the dispenser that stirs and pumps the coating slurry is equipped with a hydrometer that detects the specific gravity of the coating slurry and controls the addition of high-concentration slurry, making it possible to maintain the coating slurry at a constant component ratio at all times. As a result, the thickness of the fluorescent film coated on the inner surface of the bulb's face plate can be controlled, and a high-luminance, high-quality fluorescent surface without so-called lag can be formed.

[Brief explanation of drawings]

The drawing is a perspective view showing an outline of the configuration of a fluorescent surface coating device for a color picture tube to which an embodiment of the present invention is applied. 1...dispenser for coating slurry, 2...
...The same stirring and pressure feeding motor, 3...The injection valve for coating, 4...The same injection nozzle, 5...The pillar,
6... Parallel link arm, 7... Actuator, 8... Cup for receiving empty slurry, 9... Support arm, 10... ...Low reactor, 11...Specific gravity needle, 12...
...Same control circuit, 13...Additional slug IJ-(7
,) Dispenser, 14...Motor for stirring and pressure feeding, 15...Additional valve, 16...Collection receiver, 17...Panel chuck, a, b, c, d
・・・・・・Pipeline.

Claims (1)

[Scope of Claims] 1. An injection valve that injects coating slurry into the inner surface of the face plate of the valve, a coating slurry dispenser that constantly stirs and circulates coating slurry in a pipe line including this injection valve, and a coating slurry dispenser that An additional valve for additionally replenishing the concentrated slurry, an additional slurry dispenser for constantly stirring and circulating the additional slurry in a pipe line including the additional valve, and an additional slurry dispenser for recovering the surplus of the coating slurry and returning it to the coating slurry dispenser. In the coating device having a collection receptacle, the empty slurry receptacle is disposed at an injection position below the injection valve so that the cup can be moved forward and backward;
When the valve is not in the injection position during a predetermined injection cycle, or if necessary, prior to valve injection, the injection valve is opened and the receiver discharges the applied slurry into the cup. A coating device for the fluorescent surface of color picture tubes. 2. An injection valve that injects the coating slurry into the inner surface of the face plate of the valve, a coating slurry dispenser that constantly stirs and circulates the coating slurry in a pipe line that includes this injection valve, and a high-concentration slurry that is additionally replenished into the coating slurry dispenser. An additional valve, an additional slurry dispenser or an additional slurry pressure feeding system that constantly stirs and circulates the additional slurry in a pipe line including the additional valve, and a surplus of the coating slurry is recovered and returned to the coating slurry dispenser. In a coating device having a collection receiver, the empty slurry receiver is arranged at an injection position below the injection valve so that the cup can be moved forward and backward, and when the valve is not at the injection position in a predetermined injection cycle, Alternatively, if necessary, the injection valve is opened in advance of the valve injection, and the receiver discharges the coating slurry into the cup, and the dispenser of the coating slurry detects the specific gravity of the coating slurry and calculates the specific gravity. The collar is characterized in that a hydrometer is provided to output a signal, and the additional valve is controlled to open based on the specific gravity signal to additionally replenish high-concentration slurry from an additional slurry dispenser or an additional slurry pumping system. Fluorescent surface coating device for picture tubes. 3. Fluorescent surface coating of a color picture tube according to Patent Enclosure No. 2, characterized in that the opening timing of the additional valve based on the specific gravity signal from the hydrometer is synchronized with the injection operation signal of the injection valve. Device.