JPH1119561A - Coating device for electron gun heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for coating an electron gun heater which is capable of manufacturing an electron gun heater of uniform characteristic at a low cost and coating simultaneously a plurality of electronic gun heaters to shorten the time required for the coating. SOLUTION: When coating the surface of a long-size electron gun heater H by dipping it into a cup 8 with an open top part and filled with a stored coating liquid 4 with the help of moving means 51, 52, in such a state that the heater H is retained vertically by a holding means 3, the interior of the cup 8 is fully filled with the coating liquid 4 upto the open part in such a state that the coating liquid 4 almost overflows the cup 8 and the moving means 51, 52 move at least, either of the holding means 3 or the cup 8 so that the holding means 3 is kept distant from the cup 8 by a specified value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus for an electron gun heater, and more particularly to a coating apparatus for an electron gun heater having a simplified liquid level height, which can be easily obtained over a wide range, and which has a simplified structure. It concerns the device.

[0002]

2. Description of the Related Art A CRT, which is an electron tube, is required to have a large diameter, high brightness, high definition, and a long life.
In addition, in terms of productivity, there is always a proposition that mass production of products with uniform performance with little variation in performance must be performed stably with high efficiency and low cost.

In order to meet the above-mentioned demands, attempts have been made to improve the performance of electron gun lens systems, phosphors, shadow masks, and the like. Particularly, cathodes, which are the main components of electron guns, have high emission characteristics and high emission characteristics. It is necessary to achieve current density, long life, and low cost, and improved oxide cathodes, improved impregnated cathodes, and heaters for heating have been developed for the purpose of improving various performances and characteristics. ing.

FIG. 8 is an explanatory view of the structure of such an electron gun heater. As shown in the figure, the heater H for the electron gun has a coating portion Hc formed by coating a coating material on the surface of the twisted portion of the core wire Hw serving as a nucleus whose tip is processed into a twist shape. Have been. Mo (molybdenum) wire is used for the core wire Hw,
For example, an alumina-based coating material is used.

Here, in order to make the heater characteristics uniform, the coating length HL of the coating portion Hc must be processed uniformly. Further, it is required that the composition in the core portion of the coating portion Hc be uniform.

Meanwhile, in the production process, various steps have been conventionally improved in order to realize the above-mentioned uniformity at the production site. FIG. 9 is a diagram illustrating the principle of such a conventional coating apparatus.

As shown in FIG. 1, a coating liquid 4 is stored in a storage tank 90, and an optical liquid level sensor S is provided above the storage tank 90, and a distance D9 to the liquid level of the coating liquid 4 is provided.
0 is measured and monitored. The storage tank 90 is moved up and down by a distance d by the up and down movement mechanism 91, and as a result, the core wire Hw of the electron gun heater H, which is the material to be coated, is immersed (dipped) in the coating liquid 4. The heater H for an electron gun pulled up in a state where the coating material is added to the surface thereof is completed after a drying process.

[0008]

In the above configuration, when the electron gun heater H is immersed in the storage tank 90 (dipping), as the immersion proceeds, that is, the electron gun heater H is immersed deeply. As the volume increases, the liquid level of the coating liquid theoretically rises in accordance with the excluded volume. That is, in the figure, the liquid level was L1 in the initial state, but rises to L2.

In a general case where the diameter of the core wire Hw (see FIG. 8) is small, the increase in the liquid height due to the exclusion volume is small. Therefore, the liquid height L2 may be approximated to be approximately equal to the liquid height L1. On the other hand, if the diameter of the core wire Hw to be immersed is large, a non-negligible increase in liquid level occurs.

Thus, the core wire H of the electron gun heater is
If the immersion of w is advanced by a certain moving distance, for example, d in the figure, the coated length does not increase by the moving distance d, but further increases by the coating liquid level rise (L
2-L1) is the added coating length.

Further, when the dipping is completed and the core wire H
When w is pulled up from the coating liquid 4, the coating liquid is reduced by the amount coated on the core wire Hw.
The liquid level of the coating liquid in the tank drops as compared with the initial state L1. Further, in addition to the decrease in the amount of liquid due to the decrease in the amount of coating as described above, there is a decrease in the amount of liquid due to the volatilization of the solvent of the coating solution. As a result, the liquid height decreases to L3 as shown in the figure. Become.

Therefore, the liquid level height, which is the initial condition of the subsequent next coating processing cycle, is L3, and fluctuates from the liquid level height L1, which is the initial condition in the previous cycle.
As described above, in the related art, there is a problem that the initial condition fluctuates every cycle.

Therefore, according to the above-mentioned conventional apparatus configuration, the fluctuating liquid level is constantly measured by the optical liquid level sensor S, and the vertical mechanism of the storage tank 90 and the vertical movement mechanism so that the core wire Hw is immersed to a predetermined position. Position adjustment by the handling mechanism of the core wire Hw has been required. As described above, the prior art has a problem that a control system based on a feedback control method and advanced work are required to set the coating length to a predetermined value, thereby increasing the equipment cost. Moreover, the processing time could not be reduced.

Further, since the liquid level is detected by the sensor S and its height is controlled, there is also a problem that the sensitivity of the sensor S and the state of the liquid, such as a wave and a concentration caused by stirring, are affected.

Further, when a mechanism for stirring the coating liquid is provided to prevent the precipitation of the coating liquid and to achieve uniform concentration conditions, the height of the liquid in the stirring state is not uniform. Since the surface is limited to a very limited range, there is a drawback that simultaneous processing by immersing a large number of heaters in a wide range is difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and a heater for an electron gun having uniform characteristics can be manufactured at low cost, and a large number of simultaneous processings can be performed. It is an object of the present invention to provide a coating device for an electron gun heater capable of shortening the time required for coating.

[0017]

According to a first aspect of the present invention, there is provided a coating apparatus for a heater for an electron gun, wherein the heater for a long electron gun is vertically held by a holding means. A coating device for coating the surface of the electron gun heater by immersing the upper end portion of the side wall in a cup in which the coating liquid is stored with the coating liquid stored therein by the first moving means while holding the coating liquid. The coating liquid is a liquid amount that is filled up to just before overflowing from the upper end portion of the side wall, and the first moving unit includes the holding unit and the cup so that a distance between the holding unit and the cup becomes a predetermined value. It is characterized in that at least one of the cups is moved.

According to the above configuration, since the coating liquid stored in the cup has a liquid amount that is filled until immediately before overflowing from the upper end portion of the side wall, the liquid height is always a predetermined value. Therefore, only by setting the distance between the holding means of the electron gun heater and the cup to a predetermined value, coating processing of a predetermined length is performed. This is realized only by a simple movement of at least one of the holding means and the cup by the first moving means.

According to a second aspect of the present invention, there is provided a coating apparatus for an electron gun heater, the upper part of which is open and the coating liquid is stored in a state in which the elongated electron gun heater is vertically held by a holding means. A coating apparatus for immersing the holding means in the first moving means to coat the surface of the heater for the electron gun, wherein the first moving means has a predetermined distance between the holding means and the cup. And the cup is configured to move at least one of the cups, the cup has an upper end portion on its side wall for overflowing excess coating liquid, further includes a storage tank storing the coating liquid, and the storage tank By having a volume and a storage amount sufficient to be immersed in the coating liquid, and by moving at least one of the storage tank and the cup. Characterized by being configured by including a second moving means for discharged of the said cup being 漬没 during coating liquid in the storage tank from being the coating liquid.

According to the above arrangement, after the cup is immersed in the coating liquid in the storage tank, the cup is simply pulled out of the coating liquid again, and the excess coating liquid overflows from the upper end of the side wall. Thereby, the coating liquid height in the cup is restored to the predetermined height. This is realized only by simple vertical movement by the second moving means. Also, since the coating liquid height in the cup is maintained at a predetermined height, the distance between the holding means of the electron gun heater and the cup is simply set to a predetermined value,
A predetermined length of coating is performed. This is realized only by a simple movement of at least one of the holding means and the cup by the first moving means.

According to a third aspect of the present invention, there is provided an electron gun heater coating apparatus according to the second aspect.
A first stirrer for generating lines of magnetic force in the storage tank, and a second stirrer having magnetic induction properties in the cup, wherein the second moving means indents the cup into the storage tank. The second stirrer is rotatable by the magnetic line of force of the rotating first stirrer, and the cup is separated from the storage tank by a predetermined distance to reduce the induced magnetic force. The rotation of is stopped.

According to the above-described structure, the stirring and stopping of the coating liquid in the cup are automated with only a simple mechanism and a simple operation, and a region with a constant liquid level is realized in a wide range.

[0023]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The embodiment described below is a part of a preferred embodiment of the present invention,
Although various limitations that are preferable in terms of the technical configuration are given, the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description.

The coating apparatus according to the present invention is provided with a mechanism in which the coating liquid is pumped up from the stirring vessel and caused to overflow so that the liquid level is constant and the heater for the electron gun can easily obtain a constant coating length. Things. FIG. 1 is a side view showing a configuration of a main part in one embodiment of such a coating apparatus according to the present invention.

As shown in FIG. 1, an electron gun heater coating apparatus 50 according to the present embodiment applies a coating material such as an alumina coating material on the surface of an electron gun heater H which is a material to be coated. This is a processing plant, in which coating is performed by immersing the electron gun heater H in the coating liquid 4.

The coating apparatus 50 includes a chuck (holding means) 3 having a hand section 3A and an attachment section 3B, and vertically holding the elongated electron gun heater H by the hand section 3A, and moving the chuck 3 in a moving direction. An actuator (first moving means) 52 for raising / lowering U, a cup 8 having a side wall upper end 8Aa, the upper part of which is opened and the coating liquid 4 is stored, and the cup 8 rising / lowering in the moving direction W Cylinder (second moving means) 51 to be coated and coating liquid 4
Is provided with a storage tank 9 for storing the water.

FIG. 2 is an exploded perspective view of the cup 8 and the cylinder 51. Cup 8 has lower bottom 8B and lower bottom 8B
And a side wall 8A that rises vertically upward from the edge of the liquid container, the upper end 8Aa of the side wall 8A has a flat, uniform height.

Further, an arm 8C protruding upward from the side wall 8A is provided, and an angle at an upper end of the arm 8C is connected to a U-shaped frame 46. Frame 46
Is connected to the cylinder 51, and the frame 46 and the cup 8 move up and down by the movement of the cylinder 51 in the vertical movement direction W.

The coating liquid 4 is stored in the cup 8,
The storage amount is always considered to be full, so that the liquid level is always constant except for the edge portion where the surface tension acts, and the liquid level is flat. The material to be coated is immersed here. However, if the material to be coated is a material made of a small-diameter wire, the volume is small, so that the fluctuation in liquid height due to the immersion is small, and it is considered that liquid overflow does not occur. You can consider it. However, on the other hand, for example, when a material to be coated having a relatively large volume is immersed, the liquid is eliminated by the large volume increase, and the eliminated liquid overflows from the upper end 8Aa of the side wall 8A and separates from the cup 8. Will be. Therefore, the liquid level is always kept constant even when the material to be coated having such a relatively large volume is immersed.

On the other hand, the dimensions, ie, the diameter and depth of the storage tank 9 and the amount of the coating liquid 4 stored therein are determined by indenting the cup 8 so that the upper end 8Aa of the side wall 8A of the cup 8 is coated with the coating liquid in the storage tank 9. 4 so as to be submerged below the liquid level. According to such a configuration, it is possible to easily fill the cup 8 with the coating liquid 4 only by invading the cup 8. Further, a stirrer 10 for stirring the coating liquid 4 is provided in the storage tank 9.

The cylinder (second moving means) 51 makes the cup 8 fall into the storage tank 9 and then pulls it up. Further, the actuator (first moving means) 52 moves at least one of the chuck 3 and the cup 8 so that the distance between the chuck (holding means) 3 and the cup 8 becomes a predetermined value.

FIG. 3 is an explanatory diagram of the operation of the coating apparatus 50, and FIG. 4 is an explanatory diagram of the operation subsequent to FIG. The operation will be described with reference to FIGS. 1, 3, and 4. The coating liquid 4 in the storage tank 9 in which the cup 8 is invaginated is
And the liquid surface of the coating liquid 4 is wavy,
The cup 8 is raised to a certain height by the cylinder 51. At this time, the excess coating liquid at a position higher than the upper end 8Aa falls as an overflow Fv, and the liquid level of the coating liquid 4 in the cup 8 becomes a constant height 4a (FIG. 3). .

Since the coating liquid 4 is a high-viscosity liquid, the level of the coating liquid 4 in the cup 8 becomes stable in a short time. In this state, the chuck 3 is lowered by a certain amount in the U direction, and / or the cup 8 is further raised in the W direction. As a result, the electron gun heater H is immersed in the coating liquid 4 in the cup 8 for coating.

In the coating process, as shown in FIG. 9, it is important for quality to keep the length HL of the coating portion of the heater H for the electron gun constant. However, in the coating apparatus 50 of the present invention, the chuck 3 By moving at least one of the chuck 3 and the cup 8 so that the relative distance D from the cup 8 becomes a predetermined value, the relative relationship between the electron gun heater H and the liquid level is always kept constant. As a result, the coat length is also kept constant.

As described above, by using the overflow of the coating liquid at the time of pumping, the height of the liquid surface in the cup 8 thus pumped is always kept constant. The reading accuracy of the sensor and the influence of disturbance, which are problems in the conventional method for obtaining the positional relationship, are irrelevant, so that the management becomes easy and a simple mechanism can be provided.

Further, most of the liquid surface in the pumping cup 8 is horizontal except for the peripheral portion which shows a curvature due to surface tension. Processing becomes possible.

Further, since the amount of change in the stroke of the chuck 3 becomes the amount of change in the coat length, the adjustment and change of the coat length can be easily performed by adjusting the amount of stroke.

By the way, since the coating liquid is in the form of a slurry and precipitation starts in a short time after stirring, in order to make the liquid composition uniform in the cup 8, it is preferable that the stirring operation is also performed in the cup 8. . That is, in order to make the composition of the coating portion of the electron gun heater H uniform, it is necessary that the coating liquid in the cup 8 is sufficiently stirred so as to have a uniform concentration.

In particular, when the stirring is performed only by the stirrer 10 in the storage tank 9, such as in the case of a multi-component coating liquid composition and high viscosity, there is a possibility that the coating liquid 4 may precipitate in the cup 8. To this end, the present invention has a configuration in which a stirrer 11 is also provided on the inner bottom of the cup 8 as a second embodiment (see FIG. 1).

Here, as the stirrer (first stirrer) 10 provided in the storage tank 9, magnetic lines of force are generated.
Further, the stirrer (second stirrer) 11 provided in the cup 8 is made of a material having magnetic induction characteristics.

When the cup 8 enters the storage tank 9, the stirrer 11 in the cup 8 is rotatable by the magnetic lines of force of the stirrer 10 rotating in the storage tank 9, and the cup 8 is When the induced magnetic force decreases by a predetermined distance from the storage tank 9, the rotation of the stirrer 11 in the cup 8 stops.

That is, the cup 8 is lowered and the storage tank 9
When the stirrer 10 is immersed to a position near the stirrer 10 provided at the lower bottom, the stirrer 10 and the stirrer 11 in the cup 8 approach,
The magnetic force of the stirrer 10 acts on the stirrer 11.

Thus, the rotation of the stirrer 10 is transmitted to the stirrer 11 in the cup 8 in a non-contact manner, and the stirrer 11 rotates to stir the coating liquid 4 in the cup 8. The stirring of the coating liquid 4 in the cup 8 can be suppressed by the stirring by the stirring bar 11. During the rotation of the stirrer 11,
The liquid level of the coating liquid in the cup 8 is in a wavy state.

Then, when the cup 8 is raised in this state, the distance between the stirrer 10 and the stirrer 11 gradually opens,
The magnetic force from the stirrer 10 weakens. When the cup 8 is further raised, the rotation of the stirrer 11 is stopped. However, since the coating liquid has a high viscosity, the waving of the liquid surface disappears in a short time, the flat liquid surface is recovered, and the liquid surface is automatically kept at a constant height. Liquid level. In addition, at this time, since the dispersion state by the stirring is continued, the precipitation of the coating liquid does not occur, and the concentration of the coating liquid in the cup 8 is maintained in a uniform state.

Therefore, by immediately dipping the heater H for the electron gun in the above state, it becomes possible to perform a coating process with a uniform composition and a constant coat length. In other words, since the coating length can be defined only by the moving distance, the coating length can be set to a predetermined value without requiring a control system using a feedback control method or advanced work, and the equipment cost can be reduced. Processing time can be shortened.

Furthermore, when the dipping is completed and the electron gun heater is pulled up from the coating liquid in the cup, even if the coating liquid decreases by the amount of coating,
Simply dropping the cup into the storage tank and pulling it up can always restore the coating liquid level in the cup to the initial state. Moreover, it can be realized only with a simple mechanism without requiring a complicated and expensive mechanism.

Further, in the above-described state, a constant liquid level and a uniform concentration state are realized over a wide range in the cup 8, so that a large number of electron gun heaters H are dipped in a wide range in the cup 8. In addition, it becomes possible to perform coating processing of a large number of heaters H for electron guns at once.

FIG. 5 is a perspective view showing the entire view of one embodiment of the coating apparatus according to the present invention. In the figure,
The coating apparatus 50 according to the present invention includes a preload area A1, a dipping area A2, and a finishing area A3.
It is comprised including.

In the preload area A1, as shown in FIG. 6, by sliding the heater pallet 1 in the outer case 2, 20 electron gun heaters H in a row are dropped onto the pan P.

Next, as shown in FIG.
3A hold the 20 electron gun heaters H therebetween. Next, the traverse unit 53 holding the attachment portion 3B of the chuck 3 moves the chuck 3 to the dipping area A2 together with the 20 electron gun heaters H.

In the dipping area A2, the transported chuck 3 is moved by the actuator 52 in the U direction (in this case, vertically downward). On the other hand, the cup 8 immersed in the coating liquid in the storage tank (vessel) 9 moves vertically upward by the operation of the cylinder 51. In this state, the coating liquid is sufficiently pumped into the cup 8. Since the upper end portion 8Aa of the side wall 8A of the cup 8 has the same height as shown in FIG. 2, the level of the coating liquid that is being pumped up to a sufficient level is determined by the edge where the surface tension acts. Except for the part, the liquid level becomes uniform and a flat liquid surface is realized. In addition, the stirrer 11 in the cup 8 is rotated by the magnetic force of the stirrer 10 in the storage tank (vessel) 9.

By the above movement, the chuck 3 and the cup 8 come close to each other, so that 20 electron gun heaters H are immersed in the coating liquid 4 filled in the cup 8. The immersion depth of the electron gun heater H can be adjusted only by controlling the relative distance between the chuck 3 and the cup 8. As a result, the coat length can be made uniform only by controlling the relative distance between the chuck 3 and the cup 8.

When the coating having the uniform coating length is applied in this manner, the electron gun heater H is pulled up from the coating liquid 4. Next, the traverse unit 53 moves the chuck 3 together with the electron gun heater H to the finishing area A3.

In the finishing area A 3, the heater surface is washed with a washing liquid (alcohol) 5, then dried by blowing hot air from a drying nozzle 6, and the electron gun heater H is collected in a collection container 7.

The operation of the main part of the coating apparatus 50 will be further described. The chuck operates and descends to hold the electron gun heater. After holding, the chuck rises again. Next, the chuck is transported to the dipping area.

Here, the cylinder operates to raise the cup by a predetermined stroke. As the cup rises, the excess liquid overflows and flows down. On the other hand, the distance between the stirrer in the storage tank and the stirrer in the cup increases, and the magnetic force from the stirrer in the storage tank weakens. For this reason,
At a position opened by a predetermined distance, the rotation of the stirrer in the cup is stopped, the mixing is completed, and the liquid level is stabilized.

When the chuck arrives at the dipping area, the lowering of the chuck unit is started, and the lower end of the electron gun heater held at the tip of the chuck comes into contact with the coating liquid in the cup to start immersion. The descending amount of the chuck unit is adjusted to have a predetermined dip length.

When the coating operation is completed within a predetermined dipping time, the lifting of the chuck unit and the lowering of the cup are started simultaneously. The distance between the chuck and the cup increases,
As a result, the electron gun heater is pulled up from the coating liquid and transported to the finishing area A3.

As described above, according to the present invention, the liquid level of the coating liquid can always be kept constant by using only a simple mechanism without applying a complicated and expensive control mechanism. Since there is no need to measure with a sensor or the like, there is no influence of waves or concentration due to stirring.

Further, since the liquid level does not fluctuate as described above, it is not necessary to control the liquid level by detecting the liquid level with a sensor, which is required in the prior art, and the system is simplified. A low-cost device configuration can be realized. In addition, since a region with a constant liquid level can be obtained over a wide range, simultaneous processing of a large number of heaters can be easily performed.

[0061]

As described in detail above, claim 1 of the present invention
In the coating apparatus for the electron gun heater according to the above, the coating liquid in the cup is stored in a liquid amount immediately before the overflow,
Since the first moving means is configured to move at least one of the holding means and the cup such that the distance between the holding means and the cup becomes a predetermined value, at least one of the holding means and the cup is thus used. It is possible to perform a coating process with a uniform coat length by only a simple operation called a moving operation. This also facilitates quality maintenance and management.

According to a second aspect of the present invention, there is provided the coating apparatus for an electron gun heater, wherein the first moving means moves at least one of the holding means and the cup so that the distance between the holding means and the cup becomes a predetermined value; A cup having an upper end portion for overflowing, and a storage tank storing the coating liquid, and the storage tank has a volume and a storage amount sufficient to immerse the cup in the coating liquid, and at least the storage tank and the cup And a second moving means for moving one of the cups out of the coating liquid immersed in the coating liquid in the storage tank.

As a result, the coating liquid is filled in the cup with only a simple mechanism and simple operation, and the excess liquid overflows from the upper end by pulling up, so that the predetermined liquid level can be easily restored. The level of the coating liquid can be kept constant. Further, processing with a constant coating length can be realized only by a moving operation of at least one of the holding means and the cup.

According to a third aspect of the present invention, there is provided a coating apparatus for an electron gun heater, comprising: a first stirrer for generating lines of magnetic force in a storage tank; and a second stirrer having magnetic induction characteristics in a cup. When the second moving means makes the cup fall into the storage tank, the second stirrer is rotated by the magnetic line of force of the rotating first stirrer, and the induced magnetic force is generated when the cup is separated from the storage tank by a predetermined distance. Since the rotation of the second stirrer is stopped by the reduction, the stirring and stopping of the coating liquid in the cup can be automated with only a simple mechanism and simple operation, thus enabling simultaneous processing of many pieces Equipment can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a side view showing an essential configuration of an embodiment of a coating apparatus for an electron gun heater according to the present invention.

FIG. 2 is an exploded perspective view of a cup and a cylinder portion shown in FIG.

FIG. 3 is an explanatory diagram of an operation of the coating apparatus shown in FIG.

FIG. 4 is an explanatory view of the operation of the coating apparatus shown in FIG. 1 subsequent to FIG. 3;

FIG. 5 is a perspective view showing an entire view of an embodiment of the coating apparatus according to the present invention.

6 is a perspective view of a configuration of a preload area A1 shown in FIG.

FIG. 7 is a perspective view of the configuration of the chuck shown in FIG.

FIG. 8 is an explanatory diagram of a configuration of a heater for an electron gun.

FIG. 9 is a diagram illustrating the principle of a conventional coating apparatus.

[Explanation of symbols]

3 ... chuck (holding means), 3A ... hand part, 3B
... Attachment part, 4... Coating liquid, 8... Cup, 8 Aa... Sidewall upper end, 9... Storage tank, 10... Stirrer (first stirrer), 11. ), 5
0 ... Electron gun heater coating apparatus according to the present invention, 51 ... Cylinder (second moving means), 52 ... Actuator (first moving means), H ... Electron gun heater, U ... Moving direction , W ... moving direction

Claims (3)

[Claims] A first moving means for immersing the electron gun heater in a cup in which an upper end portion of a side wall is opened and a coating liquid is stored in a state in which a long heater for an electron gun is vertically held by a holding means; A coating device that coats a surface of the heater for coating, wherein the coating liquid stored in the cup is a liquid amount filled until immediately before overflowing from the upper end of the side wall, and the first moving unit includes: A coating apparatus for an electron gun heater, wherein at least one of the holding means and the cup is moved so that a distance between the means and the cup becomes a predetermined value. 2. The electron gun heater, wherein the elongated electron gun heater is vertically held by a holding means and immersed in a cup in which an upper part is opened and a coating liquid is stored by a first moving means. A coating apparatus that coats a surface, wherein the first moving unit is configured to move at least one of the holding unit and the cup such that a distance between the holding unit and the cup becomes a predetermined value. The cup has an upper end on its side wall to allow excess coating liquid to overflow, and further comprises a storage tank storing the coating liquid, and the storage tank has a volume and storage amount sufficient to immerse the cup in the coating liquid. Having the cup immersed in the coating liquid in the storage tank by moving at least one of the storage tank and the cup. Coating apparatus of the electron gun heater, characterized by being configured to include a second moving means for withdrawn from over preparative liquid. 3. A stirrer for generating magnetic lines of force in the storage tank, and a second stirrer having magnetic induction characteristics in the cup, wherein the second moving means drops the cup into the storage tank. When inserted, the second stirrer is rotatable by the line of magnetic force of the rotating first stirrer, and the cup is separated from the storage tank by a predetermined distance to reduce the induced magnetic force. 3. The coating apparatus for an electron gun heater according to claim 2, wherein the rotation of the second stirrer is stopped.