JPH02226636A - Manufacture of direct heating-type cathode - Google Patents

Abstract

PURPOSE:To position filaments correctly and easily so as to prepare a direct heating-type cathode easily by welding the filaments, which are extended by a frame, to leads which are inset in an insulating lead support. CONSTITUTION:Filaments 3 are extended between dividing parts 12 having a longer distance than that of an insulating lead support 1 by a punched metal plate frame 11. The dividing parts 12 are mounted on a support holding part 13, leads 2, which are inset in the support 1 and the filaments 3 are positioned correctly, welded each other by a welding jig 4 so as to position the filaments correctly and easily, and as a result, a direct heating-type cathode is prepared easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a directly heated cathode to be housed in a cathode ray tube such as a viewfinder of a video camera.

[Prior Art] A directly heated cathode that is housed in a cathode ray tube such as a viewfinder of a video camera and emits electrons has a pair of leads 2 inserted into an insulating lead support 1, as shown in FIG. ，
The filament 3 is stretched between the lead tips by welding both ends of the filament 3 to the tip 2a+2a of the lead 2, and an electron radioactive substance 6 that emits electrons approximately at the center of the filament 3.
The structure is painted and dried.

When manufacturing such a directly heated cathode, as shown in FIG.
After welding, the filament 3 is pressed and embedded onto the lead tip 2a12& by a pair of welding jigs 4.4, and after welding, the excess filament 3 on both sides is cut off, and the filament 3 is Generally, a method is adopted in which the electron radioactive substance 6 is applied and dried approximately at the center of the area.

[Problems to be Solved by the Invention] However, in manufacturing the directly heated cathode described above, when the filament 3 is positioned on the pair of lead tips 2a, 2a, the filament 3, which is easily bent, is used alone, so the lead It is not easy to align the filament 3 on the tip 2 a + 2 a, and even if the filament 3 is aligned, the leads 2 and 2 of the filament 3 are not fixed and can move freely, so the position will shift slightly and the The process of accurately positioning the filament 3 on the lead tips 2a, 2a and welding is very time-consuming and troublesome. Also, the filament 3 is connected to the lead tip 2.
There is also a problem in that unless the filament 3 is accurately positioned on the lead tips 2a and 2a, it is difficult to maintain a constant welding state of the filament 3 to the lead tips 2a and 2a.

[Means to solve the problem] Above! ! In order to solve the problem, the first method of manufacturing a directly heated cathode of the present invention includes the above-mentioned filament of a filament holder in which the filament is partially welded to a frame and stretched,
The filament of the filament holder, in which the filament is partially sandwiched and stretched between a pair of upper and lower frames, is positioned at the tips of a pair of leads inserted into an insulating lead support, and then welded. do.

Furthermore, in the second method of manufacturing a directly heated cathode of the present invention, the filament holder has both ends of the filament welded to the welded part of the frame and the filament is stretched over the frame. It is characterized by welding to the tips of a pair of leads inserted into the body, and then cutting out the part of the frame other than the welded part.

[Function] In the first method for manufacturing a directly heated cathode of the present invention, when the filament stretched on the filament holder is positioned on the tips of the pair of leads inserted in the insulating lead support, the filament The filament can be positioned relatively easily and accurately by moving the holder, and once the filament is positioned, it will not shift unless the filament holder is moved, and the lead tip can be accurately positioned. The filament can be stretched at the desired position.

Furthermore, in the second invention, when supporting the welded part where both ends of the filament of the filament holder are welded to the tips of the pair of leads inserted into the insulating lead support, the filament holder can be easily moved. Can be positioned,
By welding this welded portion to the lead tip and then cutting out the portion of the frame excluding the welded portion, the filament can be stretched between the leads without directly welding the filament to the lead tip.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a filament holder used in the method for manufacturing a directly heated cathode according to an embodiment of the first invention, and FIG. FIG.

As shown in FIG. 1, the filament holder 10 used in this embodiment has a plurality of filaments 3 partially welded and stretched around a frame 11. The frame 11 is formed by punching out a thin metal plate, and has a plurality of partitions 12 having wider intervals than the insulating lead support 1 shown in FIG. l in this frame 11
The filament 3 installed in the IS is, for example, a long coil-shaped filament obtained by winding a tungsten wire around a core wire of molybdenum or the like and melting the molybdenum of the core wire with acid or the like. A plurality of frames (four in this embodiment) are arranged in parallel at equal intervals in a direction perpendicular to frame 12, and outer frame portions 1 are arranged at equal intervals in the direction perpendicular to frame 12.
1a and each partition portion 12, and between each partition portion 12 and between the outer frame portion 11a and the partition portion 12 in the longitudinal direction.
are stretched between each.

When manufacturing a directly heated cathode using the filament holder 10, as shown in FIG.
is inserted into the insulating lead support 1 into the support holder 13.
hold within. This support holder 13 has a bottom part 15 having an opening 14 through which the lead 2.2 can be inserted into the lead support 1 and through which the lead 2.2 can pass, and a top end of the lead 2.2 when the bottom surface of the support 1 is supported. It has a side wall 16 that is approximately the same height as the position. After the lead support 1 is accommodated and held in such a support holder 13, the filament holder l is
The partition portions 12 of O are connected to the side walls 16 of the support body holder 13, respectively.
The filament 3 placed on top and stretched between the partitions 13
The holder 10 is moved and positioned so that it is located above the tips of the pair of leads 2, 2. And welding jig 4,
4 leads to the above destination #! Filament 3 on 12a, 2a
are welded under pressure, the excess filament 33' is cut off, and the filament 3 is stretched between the lead tips 2a, 2a. Thereafter, an electron emitting substance such as carbonate is applied to the substantially central portion of the filament 3, and dried and hardened to produce a directly heated cathode.

Thereafter, the above method is repeated to attach the filaments 3 of the filament holder 10 one after another to the lead tips 2a.

2 a L+: Weld and form a cathode on the filament 3 stretched between the leads 2 and 2 to manufacture a directly heated cathode.

By such a manufacturing method, the lead tip 2 of the lead support 1 &! When filament 3 is welded between 2 a,
The partition part 12 of the filament holder IO is connected to the support holder 1
By placing the filament 3 on the side wall 15 of the lead 2.2 and slightly shifting the position of the partition 12.12, the filament 3 can be accurately positioned over the tip of the lead 2.2 relatively easily. Moreover,
Since the filament 3 is partially welded and fixed to the partition part 12 of the frame 11, the filament holder 10
As long as the filament 3 is not moved, the filament 3 will not be misaligned and can be accurately welded to the lead tips 2a, 2a. Therefore, the welding state of the filament 3 on the lead tip 2as2a of each directly heated cathode becomes constant.

Next, another embodiment of the first invention will be described using FIGS. 3 and 4. As shown in FIG. 3, the filament holder 20 used in this example uses two frames 11 similar to those of the above example, and partially sandwiches the same filament 3. That is, the frames 11 are arranged vertically,
Both frames] Multiple frames (
In the embodiment, four long filaments (in the embodiment) are arranged in parallel at equal intervals, and the upper and lower frames 11 are overlapped to form a single body, and each filament 3 is attached to the outer frame portion 1 at both ends of the frame 11 in the longitudinal direction.
1a and the partition part 12 are clamped and fixed from above and below and stretched. In this case, in order to more securely sandwich the filament 3, the outer frame portion 11a of the upper and lower frames 11 is
And each partition part 12 may be fixed by welding.

Using such a filament holder 20, a direct heating mold mark-
Since the manufacturing method is substantially the same as that in the previous embodiment, a detailed explanation thereof will be omitted, but in this embodiment as well, the upper and lower partitions 12 in which the filament 3 of the filament holder 20 is partially sandwiched are used. By placing the filament 3 on the side wall 15 of the support holder 1L13 and slightly shifting the position of the upper and lower partitions 12.12, the filament 3 can be easily positioned on the tip of the lead 2.2, thereby preventing misalignment. Needless to say, since the filament 3 can be welded onto the lead tips 2a, 2a accurately without any problems, the welding state of the filament 3 on the lead tips 2a, 2a becomes constant.

In addition, when using the filament holder 10°20 as described above, it is possible to clean each filament 3 at the same time before welding the filament 3 to the lead tips 3a, 3a, or to remove electron-radioactive material from approximately the center of each filament 3. It is also possible to apply the substance all at once, so in that case, it is easier to work than when welding the filaments 3 to the lead tips 2a, 2a and then cleaning each filament 3, or applying the electron radioactive substance. can be improved.

Next, a method for manufacturing a directly heated cathode according to an embodiment of the second invention will be described with reference to FIGS. 5 and 6.

The filament holder 30 used here is a lead 21.21 with a flat tip inserted into the insulating lead support 1.
The filament 3 is stretched over a frame 31 having an interval approximately equal to that of the lead tip 21a, and a notch 32 is formed in the frame 31 at an interval approximately equal to the width of the lead tip 21a so that the filament 3 can be freely separated. Each notch 32 serves as a welded portion 33. Then, the left and right facing welding parts 3
Both ends of filament 3 are welded to 3.

When manufacturing a directly heated cathode using the filament holder 30, as shown in FIG. , position and place the welded parts 33.33 at both ends of the filament 3 of the filament holder 30, and use a welding jig (not shown) to weld the welded parts 33.3.
3 are welded to the lead tips 21a, 21a.

After welding, cuts 32.3 on both sides of the welded part 33 are made.
Fold the frame 31 at point 2 and remove the welded part 3.
After removing the other frame 31 except 3.3 and stretching the filament 3, an electron radioactive material is applied to approximately the center of the filament 3 and dried and hardened to produce a directly heated cathode.

Thereafter, by repeating the above operation, the welded portions 33 at both ends of each filament 3 of the filament 30 are successively connected to the lead tip 21a.
, 21a and cut at the notch 32 to produce a directly heated cathode.

In the second invention, the welded portion 33 of the filament holder 30
．． 33 on the lead tips 21a, 21a, the filament holder 30 can be relatively easily aligned and mounted by moving the filament holder 30, and the supported welded portions 33.33
The lead destination 121a.

The filament 3 can be stretched between the leads 21 and 21 by simply welding it to the leads 21a and separating it from the frame 31 through the notches 32 and 32 on both sides. At this time, each welded portion 33 of the frame 31 is connected to the lead end 121a.

21a and the lead tips 21a, 2.
Welding with the lead tips 2a, 2 as in the first invention
a) It is easier than directly welding the filament 3. By using the filament holder 30 on which the filament 3 is stretched in advance, any of the welded parts 33.
33 on the lead tips 21a, 21a, the welding state at both ends of the filament 3 on the lead tips 21a, 21a of each directly heated cathode remains constant.

And filament holder 30 used in the second invention
Similarly to the filament holder 1O920, the filament 3 is attached to the welded portion 33°33 of the frame 31.
It is possible to wash each filament 3 at the same time with both ends stretched, or to apply the electron radioactive substance to the substantially central portion of each filament 3 at the same time.

[Effects of the Invention] As is clear from the above description, in the method for manufacturing a directly heated cathode of the present invention, the filament stretched between the leads inserted into the insulating lead support is heated by the filament holder. It can be easily positioned and tensioned at the exact position of the lead tip, and the filament of the filament holder can be cleaned all at once, and the electronic radioactive material can be applied all at once.
This has the effect of improving workability and production efficiency, and also improving the quality of each directly heated cathode because the filament can be stretched at the precise position of the lead tip.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a filament holder used in the method for manufacturing a directly heated cathode according to an embodiment of the first invention;
The figure is a sectional view of a main part for explaining the method for manufacturing a directly heated cathode in the same embodiment, and FIG. 3 is a filament holder used in the method for manufacturing a directly heated cathode according to another embodiment of the first invention. Figure 4 is a perspective view of the body of the directly heated cathode in the same example. FIG. 5 is a perspective view of a filament holder used in the method for manufacturing a directly heated cathode according to an embodiment of the second invention, and FIG. FIG. 7 is a cross-sectional view of the main parts of the directly heated cathode, and FIG. 8 is a cross-sectional view of the main parts of the directly heated cathode. It is a sectional view of the main part. l...Insulating lead support, 2, 2 l...Lead, 3...Filament, O9 20°30...Filament holder, l. 1...Frame, 33...Welded part. Patent Applicant: Kansai NEC Corporation Straw 5 Figure M6 Figure N3 Figure Straw 4 Figure Straw 7 Figure NB

Claims (4)

[Claims] (1) A directly heated cathode characterized in that the filament of a filament holder made of a filament stretched over a frame is positioned at the tips of a pair of leads inserted into an insulating lead support and welded. manufacturing method. (2) The method for manufacturing a directly heated cathode according to claim (1), wherein the filament holder is a frame in which the filament is partially welded and stretched. (3) The method for manufacturing a directly heated cathode according to claim (1), wherein the filament holder is formed by partially sandwiching and stretching the filament between a pair of upper and lower frames. (4) The welded parts of the filament holder, which is made by welding both ends of the filament to the welded parts of the frame and stretched the filament to the frame, are welded to the tips of the pair of leads inserted into the insulating lead support. A method for manufacturing a directly heated cathode, characterized in that a portion of the frame excluding the welded portion is removed from the above.