JPH04322033A - Manufacture of direct heating type cathode - Google Patents

Abstract

PURPOSE:To prevent a coating wire from being peeled off in taking it out by setting a winding pitch of a coated metal core wire having a high melting point on a winding spool within a specific range. CONSTITUTION:A coating wire 9 is wound in one row arrangement in an electrodeposition spool 10 for winding in sequence the coating wire 9 coated continuously with carbonate inside electrodeposition liquid 1. A winding pitch of a metal core wire having a high melting point in the spool 10 is set within a 10-300 times range of the metal core wire. Accordingly, it is possible to prevent the coating wire 9 from touching an adjacent coating wire in taking out the coating wire 9 so as to prevent coating substance from being peeled off, thus obtaining a cathode having a high quality and high reliability. In the above-mentioned range, rubbing may occur in the case of less than 10 times while the coating wire 9 is hard to be taken out in the case of more than 300 times.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for manufacturing a directly heated linear cathode, which is used as a directly heated linear cathode for, for example, a fluorescent display tube. , CaCO3
The invention relates to a so-called electrodeposition process in which alkaline earth carbonates such as carbonates are electrophoretically coated.

0002

[Prior Art] Conventionally, this type of electrodeposition method uses BaCO3
, SrCO3, CaCO3, etc., or mixtures thereof, solid solutions, etc., are ground to an appropriate size, for example, usually about 0.1 to 2.0 μm in diameter, and this is combined with an organic binder to serve as a binder. An electrodeposition solution is prepared by suspending the solution in an appropriate organic solvent. Since the carbonate surface is positively charged in an organic solvent, when electricity is applied to this suspended sol, the carbonate particles move electrophoretically and are electrodeposited on the negative electrode. In the electrodeposition process for producing directly heated cathodes for fluorescent display tubes, a core wire such as a 5 to 20 μm tungsten wire is used as a negative electrode in such an electrodeposition liquid, and a positive electrode as a counter electrode is immersed, and a voltage of 50 to 500 V is applied. The core wire is continuously pulled up by applying a DC voltage, electrophoretically coated with carbonate, and a product spool is created to obtain a linear cathode. FIG. 2 shows an example of this device, and in the same figure, in the electrodeposition liquid 2 housed in the electrodeposition tank 1,
For example, a tungsten core wire 4 is inserted into a cylindrical electrode as the counter electrode 3, and electrodeposition is performed by connecting a DC power source 5 with the counter electrode 3 as an anode and the tungsten core wire 4 as a cathode. Note that 6 is a current-carrying spool, and 7 is a direction changing spool. Additionally, electrolytes, surfactants, etc. may be added to make electrodeposition more effective. In this way, the core wire spool 8
The tungsten core wire 4 wound around is sequentially pulled out,
The carbonate is coated continuously in the electrodeposition liquid 1 and is wound up one after another into an electrodeposition spool 10 as a coated wire 9 .

0003

[Problems to be Solved by the Invention] However, according to the conventional method of manufacturing a directly heated cathode, the electrodeposited spool 10
The winding pitch is 10 times the wire diameter of the coated wire 10.
It was less than twice that. Therefore, as shown in the plan view and cross-sectional view in FIGS. 3(a) and 3(b), the second and subsequent coating lines 92 and 93 are placed next to the first coating line 91 on the electrodeposited spool 10. They will be wound up next to each other. As a result, when the coated wire 9 is taken out from the electrodeposited spool 10 in the next step and assembled, the side surface of the coated wire 9 rubs against the side surface of the adjacent wire, causing the carbonate substance coated on the surface of the coated wire 9 to peel off. There was a problem that this was likely to occur.

Therefore, the present invention has been made to solve the above-mentioned conventional problems, and its object is to provide a directly heated cathode in which the coating material does not peel off when the coated wire is taken out from the take-up spool. The purpose is to provide a manufacturing method.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the method for manufacturing a directly heated cathode according to the present invention is such that the winding pitch of a coated high-melting point metal core wire on a winding spool is The wire diameter is 10 to 300 times the wire diameter of the high melting point metal core wire.

[0006]

[Operation] In the present invention, the distance between adjacent coating lines is increased, and there is no possibility of them rubbing against each other.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings. FIG. 1 is a diagram showing the structure of a take-up spool for explaining an embodiment of the method for manufacturing a directly heated cathode according to the present invention, and FIG. 1(a) is a plan view, and FIG. 1(b) is a cross-sectional view. It is a diagram. In the figure, an electrodeposition spool 10 is coated with carbonate continuously in an electrodeposition liquid 1 (not shown) and is wound up sequentially as a coating line 9, including a first coating line 91 and a second coating line 92. , the third-stage coated wire 93 and the subsequent coated wires are wound in a row. Winding into such a structure is possible as long as the winding pitch is 10 times or more the wire diameter of the coated wire 9.

[0008] By winding in this way, when the coated wire 9 is taken out in the next step, it will not rub against the adjacent coated wire, and there will be no peeling of the coating material.

[0009] In the above-mentioned embodiment, the reason why the winding pitch is set to be in the range of 10 to 300 times the coating wire diameter is that if the winding pitch is less than 10 times, the coating line of the second and subsequent stages will be adjacent to the coating line of the first stage. are wound up next to each other, and if the number exceeds 300 times, it becomes difficult to take out the coated wire. Therefore, 1 of the coating wire diameter
A range of 0 to 300 times is extremely good for practical use.

0010

[Effects of the Invention] As explained above, according to the present invention,
By setting the winding pitch of the coated high-melting point metal core wire on the winding spool to a range of 10 to 300 times the wire diameter of the coated high-melting point metal core wire,
Since the coating material does not peel off when the coated wire is taken out from the take-up spool, it has an extremely excellent effect in that a directly heated cathode with high quality and reliability can be obtained.

[Brief explanation of drawings]

FIG. 1(a) is an enlarged plan view of essential parts showing a structure for winding a coated wire onto a winding spool for explaining an embodiment of the method for manufacturing a directly heated cathode according to the present invention;
(b) is an enlarged sectional view of the main part.

FIG. 2 is a sectional view showing the configuration of an electrodeposition apparatus.

FIG. 3(a) is an enlarged plan view of a main part showing a structure for winding a coated wire onto a take-up spool according to a conventional method for manufacturing a directly heated cathode, and FIG. 3(b) is an enlarged sectional view of the main part. .

[Explanation of symbols]

1 Electrodeposition bath 2 Electrodeposition liquid 3 Counter electrode 4 Tungsten core wire 5 DC power supply 6 Energizing spool 7 Direction change spool 8 Core wire spool 9 Coated wire 91 Coated wire 92 Coated wire 93 Coating wire 10 Electroplated spool

Claims (1)

[Claims] 1. A method for producing a directly heated cathode, in which a high melting point metal core wire is coated with an electron emitting material by electrophoresis, and the high melting point metal core wire coated with the electron emitting material is wound onto a spool. The winding pitch of the coated high melting point metal core wire on the spool is 1 of the wire diameter of the coated high melting point metal core wire.
A method for producing a directly heated cathode, characterized in that the heating rate is in the range of 0 to 300 times.