JP3484890B2 - Electrophoresis device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for forming a film by a novel electrophoretic method, and more particularly, to a high performance in which an insulating film filling rate is increased when forming an insulating film of a heater for heating a cathode ray tube cathode. Electricity that can easily produce heaters
The present invention relates to an electrophoretic device .

[0002]

2. Description of the Related Art Conventionally, indirectly heated cathode ray tubes and impregnated cathode ray tubes have a heater for heating a cathode. Fig. 2 shows the appearance of the heater. The metal wire 1 wound in a coil shape is covered with an insulating film 2, and a dark layer 3 is formed outside the insulating film 2.
The heater is located in a tubular metal cover called the sleeve 4. In the impregnated cathode heater, the impregnated cathode 5 is arranged on the top of the heater. An enlarged cross section of the coil portion is shown in FIG. Metal wire is a conductive material with heat resistance,
For example, tungsten (W) or rhenium-tungsten alloy (Re-W) is used. The metal wire is first heated in the hydrogen atmosphere as it is to clean the surface, and then an insulator such as alumina is applied to the surface of the metal wire by a method such as electrophoresis, spraying or dipping. Form.
The heater energizes the metal wire to heat the cathode. Therefore, as the cathode ray tube is turned on and off, the cathode ray tube repeatedly operates in a temperature environment of about 1200 ° C. when energized and at room temperature when stopped. In an environment of high temperature and intermittent energization, sintering causes grain growth of inorganic substances constituting the insulating film and contraction of the insulating film.
As a result, peeling or cracking of the insulating film has occurred, or metal wires have come into contact with each other, causing insulation failure in a short period of time. Also,
Defects in the metal wire were also broken. As a means for improving them, in JP-A-3-37988, an electrolyte in an electrophoretic method is selected according to the purpose to form an insulating film having a uniform film filling rate a plurality of times to improve strength and insulating properties, A long-life heater is obtained by preventing cracks in the insulating film. Kohei
In JP-A 7-220617, a film forming voltage profile and current density in the electrophoretic method are specified to reduce and disperse individual voids to obtain a high performance heater.

Film forming methods include thermal spraying, vapor deposition, and CVD (Chemic
Al Vapor Deposition), spraying, dip coating, electrophoresis and various other methods, which are selected according to the use environment and productivity of the film to be formed. In particular, the electrophoresis method has a wide application range because the apparatus is simple and a film thickness of several μm to several mm can be easily formed.

[0004]

In order to prevent contact between metal wires and to improve insulation characteristics, it is important to increase the ratio of the insulating material filled between the metal wires. When the amount of the insulating material per unit volume increases, the insulating property improves, the number of contact points between the insulating materials also increases, and the film strength also improves. In the conventional technology, an electrolyte to be added to a liquid in which an inorganic substance used for forming a film by electrophoresis is added is selected according to the purpose, and an insulating film having a uniform film filling rate is formed by performing film formation and firing a plurality of times. However, cracks in the insulating film have been prevented by improving the strength and insulating properties of the insulating film. However, since the film formation and firing are repeated a plurality of times, there are many steps, and it is difficult to adjust the film thickness and the coating length, and it is difficult to maintain the heater manufacturing accuracy.
Further, the method of controlling the film forming voltage or current of the power source is easily affected by the liquid composition variation in the film forming step and the mounting accuracy of the heater immersed in the liquid. Therefore, there is always a stable film formation state, and moreover, a simple film formation method capable of forming the film thickness in one step and easily correcting even if the number of heaters forming the film at one time changes. Was wanted.

[0005]

SUMMARY OF THE INVENTION The present invention is a power supply and an inorganic material.
Reservoir container for storing dispersion liquid in which substances are dispersed, and the reservoir container
A device that circulates or stirs the dispersion liquid inside and coats inorganic substances
And a working electrode that holds the material to be energized
Counter electrode and a reference electrode that can measure the standard hydrogen electrode potential
And the working electrode, the counter electrode and the reference electrode are
The potential between the working electrode and the reference electrode in contact with the dispersion liquid in the vessel
Or a control device for controlling the current between the working electrode and the counter electrode
An electrophoretic device having: Furthermore,
The present invention stores a power source and a dispersion liquid in which an inorganic substance is dispersed.
Circulate or stir the liquid storage container and the dispersion liquid in the liquid storage container.
Device and a working electrode for holding the material coating the inorganic substance.
A pole, a counter electrode for energizing the working electrode, and a standard hydrogen electrode
Reference electrode that can measure electric potential and external with electrolyte solution
Container, dispersion in the reservoir and electrolyte in an outer container
And a tube for electrically connecting the solution through an electrolyte,
The working electrode and the counter electrode are in contact with the dispersion liquid in the liquid storage container,
The dispersion liquid in the storage container and the electrolyte solution in the outer container are the electrolyte
And the reference electrode is electrically connected to the external capacitor.
Between the working electrode and the reference electrode
Control device for controlling electric potential or current between working electrode and counter electrode
An electrophoretic device having: In the field of electrochemistry, using three electrodes, a working electrode, a counter electrode, and a reference electrode, the properties of ions in a dispersion liquid are investigated, and the material of the working electrode is changed to measure the type of material and the oxidation and reduction reaction of ions. It is a general method for investigating. In the present invention, this method was applied to electrophoresis. In ordinary electrophoresis, the migration speed of charged powder or ions in the dispersion is proportional to the voltage, so the potential difference applied between the working electrode and the counter electrode is important. In addition, since the state of ions varies depending on the pH when the powder is charged, pH, which is the hydrogen index, may be measured. However, in the generally performed electrophoretic method, the reaction at the electrode interface may occur, and the method of adjusting the voltage of the power source, which is the potential difference between the working electrode and the counter electrode, is the mainstream as a means for adjusting the migration speed or the migration amount. . The pH is a numerical value indicating the amount of hydrogen ions in the dispersion liquid and is not directly related to the potential for generating hydrogen. Therefore, in electrophoresis, a reference hydrogen electrode was added to measure the standard hydrogen electrode potential, or a manufacturing method for forming a film using it was not found.

The present invention controls the working electrode potential with respect to the standard hydrogen electrode potential at the time of forming a film by the electrophoretic method, or moves between the working electrode and the counter electrode so that the working electrode potential with respect to the standard hydrogen electrode potential becomes a set value. The state of the surface of the working electrode is positively controlled by controlling the applied current, and a high-performance film is easily formed.

Generally, the standard hydrogen electrode potential is determined by the material of the electrode to be dipped, the type of dispersion, the valence of the electrolyte in the dispersion, the amount added, and the reactivity.

In the electrophoretic method, when a working electrode and a counter electrode as electrodes are immersed in a dispersion liquid in a reservoir and an electric current is applied thereto, an inorganic substance charged in the dispersion liquid migrates to a working electrode corresponding to a charged polarity, and acts. This is a method of forming a film by adhering on the electrode. When the dispersion liquid contains water, electrolysis of water is caused by energization, and oxygen is generated when the polarity of the electrode is positive, and hydrogen is generated when the polarity of the electrode is negative. The generation of these bubbles dissociates the adhesion of the inorganic substance on the electrode. If the generation of bubbles can be controlled, the inorganic material can be easily filled, and a high-density film can be formed. FIG. 1 shows an outline of the device. Working electrode 7 and counter electrode 8 in the conventional electrophoresis method
In addition to the above electrode, a reference electrode 9 capable of measuring the standard hydrogen electrode potential is added. Hydrogen is generated when the working electrode potential is more negative than the standard hydrogen reference potential. The power supply 12 can measure the potential between the reference electrode 9 and the working electrode 7, and can control the current flowing between the working electrode and the counter electrode so that this potential becomes a set value. The circulation pump 13 circulates the dispersion liquid in the storage container to prevent sedimentation of inorganic substances in the dispersion liquid.

Generally, the standard hydrogen electrode potential is determined by the material of the electrode to be dipped, the type of dispersion, the valence of the electrolyte in the dispersion, the amount added, and the reactivity. In the prior art, control of voltage and current is performed by the device voltage and device current of the power supply, and the film is formed at a set value that is independent of the standard hydrogen electrode potential. Therefore, when the same type of electrode is repeatedly used to form a film, the film morphology varies depending on the composition variation of the dispersion liquid, and in the heater, the filling degree of the inorganic substance in the portion sandwiched by the metal wires (FIGS. 3 and 6) decreases. There was a tendency. If the standard hydrogen electrode potential is obtained from the reference electrode of the present invention and the potential or current is controlled based on this to form a film, it is possible to control the generation of bubbles that have a great influence on the film morphology even if the composition of the liquid changes. .

In the present invention, a reference electrode is added during the electrophoretic method so that the standard hydrogen electrode potential can be obtained, and the film formation voltage and current are controlled based on the reference electrode to form a film, thereby forming a working electrode. The bubbles generated above can be controlled, and the portion sandwiched by the metal wires can be stably filled with the inorganic substance. As a result, when a film is formed on the heater, an insulating material is used as an inorganic material, so that the insulation characteristics and mechanical strength can be improved, and a long-life heater can be obtained. or,
According to the present invention, since the film forming step is completed in one step, a highly accurate heater can be easily manufactured. Furthermore, even if the composition of the dispersion liquid changes, the film forming voltage and current can be controlled accordingly, and a high-performance film can be easily formed.

The present invention relates to a product in which a film is formed by an electrophoretic method, and particularly, in a process of forming an insulating film of a heater for heating a cathode ray tube cathode, a high-performance heater having an increased insulating film filling rate can be used in a simple and simple process. For easy production.

In the electrophoresis method, a liquid in which an inorganic substance to be coated is dispersed is used. Inorganic substances in this dispersion settle out over time. When the working electrode has a size in millimeters, the film is formed immediately below the surface of the dispersion liquid, so that the influence of sedimentation is large. Therefore, in the apparatus configuration of FIG. 1, it is essential that the dispersion liquid in the liquid storage container is a device that circulates or stirs the dispersion liquid in order to prevent sedimentation of inorganic substances. Of course, circulation and stirring may be stopped during the film formation so that the waves on the dispersion liquid surface do not affect the film formation on the working electrode. Although it is desirable to use platinum for the counter electrode, which has little influence on the potential, a conductive material may be used in consideration of the elution of ions into the dispersion liquid. There are various electrodes such as a hydrogen electrode, a calomel electrode, and a silver / silver chloride electrode as the reference electrode, and any electrode may be used as long as the output potential can be converted into a standard hydrogen electrode potential.

Further, the reference electrode functions when it is electrically connected to the working electrode through the electrolyte. In FIG. 4, an electrolyte solution 1 having the same composition as the dispersion liquid 10 in the liquid storage container 11
A tube 14 obtained by solidifying 5 with gelatin or agar is used to establish conduction with the electrolyte solution 15 in the outer container 16 so that the potential between the reference electrode and the working electrode can be measured. If the reference electrode is installed outside, it is possible to prevent the influence of ions leaching from the reference electrode.

By controlling the electric potential to be equal to or lower than the hydrogen generation potential or the oxygen generation potential during the film formation, the film formation can be performed while preventing the generation of bubbles. However, since the electrophoretic method also requires a potential for migrating the powder, a film forming condition that can increase the filling rate while suppressing the amount of bubbles generated is necessary.

In the examination of film forming conditions, the quality of film formation was evaluated by the filling rate of the film cross section. The analysis position is a portion 6 sandwiched by the metal wires 1 on the heater cross section in FIG. The filling rate is the ratio of the cross-sectional area of the inorganic material to the total area on the photograph obtained by photographing the cross section of the insulating film at the analysis position. The portion 6 sandwiched by the metal wires is a portion having a low filling rate during film formation.
Therefore, it is important to increase the filling rate of this portion in order to obtain a high performance film. FIG. 5 shows the film filling rate at the time of film formation in the device configuration of Example 1 described later. When the value of the working electrode potential (vsNHE) with respect to the standard hydrogen electrode potential was low, the film filling rate tended to be high. It is considered that when the working electrode potential is high, the amount of bubbles generated (hydrogen in this case) is large and the filling of the membrane is hindered. From Figure 5, the working electrode potential is -6V (vsNHE)
A highly filled film can be obtained by the following. Desirably, the working electrode potential is −3 V (vsNHE) or less. When the working electrode potential is higher than -6V (vsNHE), the film filling rate is 50%.
Less than

FIG. 6 shows the relationship between the working electrode potential (vsNHE) and the film formation rate. The working electrode potential (vsNHE) is proportional to the film formation rate. The deposition rate is low under the condition that the working electrode potential is low to obtain a highly filled film. Therefore, the working electrode potential at the time of film formation of the portion sandwiched between the metal wires that need to be highly filled is set to -6 V (vsNHE) or less, and the working electrode potential is increased after the film is formed in the portion sandwiched by the metal wires. Then, when the film formation speed is increased to form the film to a predetermined film thickness, the film sandwiched between the metal wires and highly filled can be formed in a short time. To obtain a highly filled membrane, the working electrode potential should be
It is necessary to control the voltage to 6 V (vs NHE) or less. Even when a film is formed by current control, the same effect can be obtained if the working electrode potential with respect to the standard hydrogen electrode potential is -6 V (vsNHE) or less.

By using the electrophoresis apparatus of the present invention
Inorganic porous film sandwiched between the conductive material or the conductive film
If the cross-section filling rate of 55% or more is higher than 70%,
A heater for heating a round tube can be manufactured. Especially at least
Working electrode voltage against standard hydrogen electrode potential within 1 second after energization
Must be -6V or less, at least 1 second after energization
Working electrode potential is -6V or less with respect to standard hydrogen electrode potential of
And the absolute value of the working electrode potential
Is preferably increased. Conductive material with heat resistance
Alternatively, an insulating material having a conductive film is coated with an inorganic porous film.
By using the above-mentioned electrophoretic device to form 10 ^-7 P
Apply a voltage of 6.3V or more and 7.6V or less in an atmosphere of a or less.
90% or more of the bras that can operate for over 8,000 hours
It is possible to obtain a heater for heating untube. The present invention
An electron gun provided opposite to the light surface and the fluorescent surface,
The electron gun is a sleeve, and the cathode is arranged at the tip of the sleeve.
The pellet and the cathode heating heater mounted in the sleeve.
And the heater is a cathode heater coated with an inorganic insulator.
In cathode ray tubes equipped with a heater for cathode,
The above-mentioned heater is used for the battery. This device is not limited to the cathode ray tube heater, but can be applied to an electrophoretic method using a dispersion medium in which bubbles are generated when energized.

[0018]

DETAILED DESCRIPTION OF THE INVENTION

(Example 1) A 3% Re-W metal wire having a diameter of 30 µm was wound on a Mo metal core wire having a diameter of 110 µm to form a heater coil.

The dispersion is composed of Al (NO ₃ ) ₃ , M as an electrolyte component.
g (NO ₃₎ the ₂ · 6H ₂ O was dissolved in aqueous ethanol solution 8 l, average particle size 4μm of alumina (Al ₂ O ₃₎ having a purity of 99.9% or more as inorganic powder was 9kg formulation.

In the apparatus configuration of FIG. 1, 30 heater coils are used as working electrodes and aluminum electrodes are connected as counter electrodes,
The reference electrode is an electrode in which silver / silver chloride is immersed in saturated KCl (A
g / AgCl / saturated KCl) was used. The potentials of the reference electrode and the standard hydrogen electrode (NHE) are 0.199V (vsN
HE). Each electrode was immersed in the dispersion liquid, and the working electrode potential was kept at -5 V (vsNHE) constant for 10 seconds to form a film.

Thereafter, the average particle size is 1 μm and the purity is 99.9%.
A liquid in which the above tungsten powder was dispersed and suspended was applied by dip coating to form a dark layer.

Next, this was baked in a hydrogen atmosphere at 1600 ° C. for 5 minutes. The insulating film thickness including the dark layer after firing was 110 μm.

After firing, the Mo metal core wire was dissolved and removed with a mixed solution of nitric acid and sulfuric acid, washed with water and dried to prepare a heater.

The conditions for forming the alumina film for comparison are as follows. In Comparative Example 1, a device voltage of 80 V is applied for 3 seconds, and in Comparative Example 2, the current density is 0.35 mA / mm ² for 10 seconds and 1.5 mA / m.
Electricity was applied for 2 seconds at m ² . Both heaters are heaters after which a dark layer is applied and fired in a hydrogen atmosphere to remove the Mo core wire.

The filling rate of the portion 6 sandwiched between the metal wires in the film cross sections of the heaters of this example and the comparative example was measured in four fields of view for one heater, and the average value was obtained. This measurement was calculated for each of 20 heaters. The results are shown in Table 1.

[0026]

[Table 1]

The average filling rate of the whole measurement is 40 in Comparative Example 1.
%, Comparative Example 2 was 55%, and this Example was 57%. The yield of heaters having an average filling rate of 55% or more is shown in Comparative Example 1
Was 0%, Comparative Example 2 was 55%, and this Example was 75%.

FIG. 7 shows the heater current and the leak current when the heaters of this example and the comparative example were subjected to the life test. The life test was performed at a voltage of 7.6 V, which is higher than the heater operating voltage of 6.3 V. In the energization cycle, energization is carried out for 5 minutes, and rest for 15 minutes is repeated. If the insulating film deteriorates or cracks occur, the leak current increases and the heater current decreases. In Comparative Example 1, when the life test time exceeds 4000 hours, the leak current increases,
In contrast to the decrease in the heater current, in the heaters of Comparative Example 2 and the present invention, there is no change until 6,000 hours. In addition, the yield when each of the 100 heaters was subjected to the life test is shown in FIG.
Shown in. The yield here is the ratio of the heaters that are operating normally excluding the heaters in which the decrease in the heater current or the increase in the leak current exceeds the specified value during the life test. The yield of the life test 8,000 hours is 0% in Comparative Example 1, 80% in Comparative Example 2, and 92% in the present invention. The product of the present invention has excellent durability and high reliability as compared with the conventional heater.

FIG. 9 shows the number of times of film formation and the insulating film defect rate when the film was continuously formed without exchanging the dispersion liquid in the present invention and Comparative Example 2. In Comparative Example 2, the defect rate increases from around 100 times, while in the heater of the present invention,
The defect occurrence rate is low even after 88 times, and the defect occurrence rate is low even when a film is formed many times by using the same liquid by controlling the working electrode potential based on the standard hydrogen electrode potential, and stable production is possible.

(Embodiment 2) 30 heater coils manufactured in the same manner as in Embodiment 1 were energized at a working electrode potential of -4 V (vsNHE) for 11 seconds in an apparatus configuration (FIG. 4) in which a reference electrode was installed outside. A film was formed. After that, a heater was produced in the same process as in Example 1 and a life test was performed. As a result, the same result as in Example 1 was obtained.

(Embodiment 3) Thirty heater coils manufactured in the same manner as in Embodiment 1 are used as working electrodes, and the working electrode potential during film formation is from -3V (vsNHE) to -0.5V (vsNHE).
The potential was increased at a rate of / sec and a current was applied for a total of 7 seconds to form a film. Final working electrode potential is -6.5V (vsNHE)
Is. After that, a heater was produced in the same process as in Example 1 and a life test was performed. As a result, the same result as in Example 1 was obtained.

(Embodiment 4) FIG. 10 is a sectional view of a cathode ray tube. The cathode ray tube is a funnel-shaped glass tube in which an electron gun 17 and a fluorescent screen 18 are enclosed. The glass bulb consists of a bulging cone and a thin cylindrical neck, and the bottom of the cone is a phosphor (a substance that fluoresces when irradiated with an electron gun).
Is applied, and it is enclosed in a high vacuum. Electron gun 1
Reference numeral 7 denotes a cathode 20 which emits electrons by a heater 19 for heating a cathode manufactured by using the film forming method of the present invention, and the flux of the electrons is collectively accelerated as an electron beam at a high speed, and at the same time, a fluorescent screen is formed. Cylindrical electrode (grid) for focusing
21. A deflection yoke 22 and an anode button 23 are provided, and a conductive film 24 (aluminum film covering the fluorescent screen 18) is formed on the inner surfaces of the neck portion and the cone portion. A socket pin 25 for electrical connection is provided behind the electron gun 17.

The cathode ray tube incorporating the heater is the first embodiment.
As shown in, long life operation is possible and its reliability is improved.

[0034]

The present invention is a method for easily forming a high-density film in a simple process by measuring and controlling it based on the standard hydrogen electrode potential when forming a film by electrophoresis. Especially in the process of forming the insulating film of the heater for cathode ray tube cathode heating, it is possible to easily produce a high-performance heater having an increased insulating film filling rate and improved insulating film strength and insulating characteristics. Has the effect of reliability and long life.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus in which a reference electrode is added when a film is formed by an electrophoretic method.

FIG. 2 is a sectional view of a heater.

FIG. 3 is a cross-sectional view of a heater coil partial enlarged film.

FIG. 4 is a block diagram of an apparatus in which a reference electrode at the time of film formation by an electrophoretic method is installed outside.

FIG. 5 is a characteristic diagram of hydrogen reference potential and membrane filling rate during electrophoresis.

FIG. 6 is a characteristic diagram showing the relationship between hydrogen reference potential and film thickness during electrophoresis.

FIG. 7 is a characteristic diagram showing changes in the leak current and the heater current over a lifetime.

FIG. 8 is a characteristic diagram of a change in yield over time.

FIG. 9 is a characteristic diagram of the number of times of film formation by an electrophoretic method and the insulating film defect rate.

FIG. 10 is a sectional view of a cathode ray tube.

[Explanation of symbols]

7 ... Working electrode, 8 ... Counter electrode, 9 ... Reference electrode, 10 ... Dispersion liquid, 11 ... Storage container, 12 ... Power supply, 13 ... Dispersion liquid circulation pump.

Front page continued (72) Inventor Norihide Shibata 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. Electronic Device Division (56) Reference JP-A-7-220617 (JP, A) (58) Fields investigated ( Int.Cl. ⁷ , DB name) C25D 13/02 C25D 13/22 H01J 1/22 H01J 9/08 H01J 29/04

Claims (2)

(57) [Claims] And 1. A power, a reservoir container for storing a dispersion obtained by dispersing an inorganic substance, a device for performing the circulation or stirring the dispersion in the reservoir vessel, acts to retain the material covering the inorganic an electrode, a counter electrode Ru is energized to the working electrode, and a reference electrode capable of measuring the standard hydrogen electrode potential, the reference electrode and the working electrode and the counter electrode is in contact with a dispersion of the liquid storage container, before
It is characterized in that it has a control device for controlling the current between the potential or the working electrode and the counter electrode between the serial working and reference electrodes
Electrophoresis device. 2. A power, a reservoir container for storing a dispersion obtained by dispersing an inorganic substance, a device for performing the circulation or stirring the dispersion in the reservoir vessel, acts to retain the material covering the inorganic an electrode, a counter electrode Ru is energized to the working electrode, a reference electrode capable of measuring the standard hydrogen electrode potential, an external container reservoir electrolyte solution, the electrolyte solution of the dispersion liquid and the external container of the liquid storage container And a tube electrically connected through the electrolyte ,
The working electrode and the counter electrode is in contact with a dispersion of the liquid storage container, before
Serial electrolytic solution of the dispersion liquid and the external container in reservoir container is electrically connected through the electrolyte, the reference electrode is in contact with the electrolyte solution in the outer container, the potential between the reference electrode and the working electrode or Control device for controlling the current between the working electrode and the counter electrode
An electrophoretic device having a storage device.