JPH01109634A - Impregnated type cathode structure - Google Patents

Abstract

PURPOSE:To increase the adhesive strength between the component members and to improve the heat conductivity by placing a thin disk with plural grooves in a radial form between the enclosed surface of a metal sleeve and the bottom surface of a metal cup, and welding and fixing the three members. CONSTITUTION:A thin metal disk 6 is fixed on the enclosed end surface of a metal sleeve 3, coaxially with the sleeve. In the disk 6, plural grooves 6a to 6d are furnished in a radial form from the center. At the center of the disk 6, a penetrating hole 7 is arranged. The diameter of the hole 7 is made in the size to accomodate the part of crossing of two cathode holding wires 5. After these cup 2, disk 6, sleeve 3, and holding wires 5 are welded and fixed integrally, an impregnated type cathode 1 is installed in the cup 2, and both members are fixed by welding. Consequently, the adhesive strength between the component members is improved extensively. The heat conductivity between the all members is also improved, and a stable electron emitting performance can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an impregnated cathode structure in which each member is strongly bonded and has good thermal efficiency.

[Conventional technology]

For impregnated cathodes, the cathode temperature during use is 1000 to 1100.
It is necessary to keep the temperature at about 0.degree. C., and therefore various efforts have been made to improve thermal efficiency.

For example, in Japanese Patent Application Laid-Open No. 56-168316, the end side of a metal sleeve with a built-in heater and an impregnated cathode pellet attached to the outside of the closed end is covered with a metal heat reflective screen. In the cathode unit that surrounds the pellets and the suction.

The cathode shaft consisting of a rib is made to stand on its own by a metal strip (with a thin cross section (flat rectangular)) or a thin metal wire (for example, a W-Re wire with a diameter of 0.05 fi) with low thermal conductivity fixed to the bottom of the pellet. , is disclosed for hanging in a heat reflective screen.

Furthermore, Japanese Patent Application Laid-Open No. 61-288339 discloses that a powder of a high melting point metal or its oxide and an inorganic binder are mixed on the inner surface of a metal sleeve that has a built-in heater and an electron emission emitter attached to the outer surface of the closed end wall. The disclosure discloses forming a heat-absorbing membrane by coating and sintering, and also includes a metal sleeve containing impregnated cathode pellets attached to the outer surface of the closed end wall of the metal sleeve. the bottom of the cup,
It is shown supported by four thin metal wires.

FIG. 2 shows an example of such a conventional impregnated cathode structure.
% porous tungsten substrate, BaO+Cab,^l
It is made by melting and impregnating an electron-emitting substance such as 2o3,
For example, it is housed in a bottomed metal cup 2 made of a high melting point metal material such as solid metal. - On the other hand, a metal sleeve 3 whose upper end is closed with a flat surface has a built-in heater 4. The metal cup 2 has its bottom surface attached coaxially with the back to back on the closed end surface of the metal sleeve 3, and between these two, there are two diameter 30 mm which are crisscrossed on the central axis common to both. A tungsten cathode support wire 5 with a circular cross section of ~50 μm is provided, and this support wire 5 is connected to the metal cup 2.
The metal sleeve 3 is welded to both the bottom surface and the closed end surface of the metal sleeve 3 by resistance welding, laser welding, or the like. Furthermore, both ends of each of the two support wires 5 are attached to the end surface of a metal cathode support cylinder that is fitted and fixed, for example, into a through hole of an insulating substrate made of a ceramic or crystal glass material (not shown). are fixed at four locations at 90 degree intervals to form one impregnated cathode assembly in which the impregnated cathode is held at a predetermined relative position with respect to the cathode support tube.

Such an impregnated cathode structure is attached to a cathode ray tube such as a picture tube or image pickup tube to emit electrons, but in order to do so,
It is necessary to maintain the impregnated cathode pellet at a high temperature of 1100°C, and in order to obtain such a pellet temperature, it is necessary to set the temperature of the heater 4 to 1300 to 1400°C.

[Problem that the invention seeks to solve]

The above conventional technology uses gold NIIB, which has problems such as being easily bent in a specific direction and easily deformed by stress strain, as a means for fixing the relative position of the impregnated cathode pellet with respect to the support while suppressing heat loss due to conduction. We avoid deformation during high-temperature use by avoiding strips and using thin tungsten support wires with a circular cross section. However, since the welded structure is made by intersecting the lines of the circular cross section and stacking them so that they are sandwiched between the bottom surface of the metal cup and the closed end surface of the metal sleeve, the joint strength by spot welding is low. When a long-term life evaluation test was conducted on the impregnated cathode assembly, fatal damage such as weld peeling occurred between the bottom of the metal cup, the closed end of the metal sleeve, and the criss-crossed cathode support wires.

As a countermeasure to this problem, it was first considered to provide a hole in the center of the closed end surface of the metal sleeve to escape the thickness of the cross intersection of the cathode support wire. However, even with this method, the cathode support wire is made of a hard material such as tungsten with a high melting point, and the metal cup is also made of a thin plate of high melting point, such as molybdenum, with a thickness of, for example, 25 μm. It is extremely difficult to securely install and secure the device without causing damage. In any case, the bottom surface of the metal cup and the closed end surface of the metal sleeve are overlapped with a cross-shaped support line of 30 to 50 μm in diameter interposed between them, so at least in the vicinity of the support line, the above-mentioned diameter This creates a gap of some degree, and the heat conduction between the metal sleeve and the metal cup becomes extremely poor, resulting in a heavy reliance on heat radiation. For this reason, not only are stable electron emission characteristics not obtained, but it is also necessary to raise the heater temperature to a higher temperature, causing deterioration of the welding strength of various parts of the cathode structure, resulting in a vicious cycle in which reliability is significantly impaired.

The present invention solves the problems of the conventional impregnated cathode structure as described above, has high bonding strength between the constituent members, and can efficiently heat the cathode pellet by thermal conduction with the heat generated by the heater, resulting in a stable structure. An object of the present invention is to provide an impregnated cathode structure that provides electron emission characteristics.

[Means for solving problems]

In order to solve the above problems, the present invention includes a metal sleeve with a built-in heater and one end closed, a metal cup with bottoms attached back to back to the outside of the closed end of the metal sleeve, and a cup that is housed in the metal cup. An impregnated cathode structure comprising an impregnated cathode that emits electrons from the open side, and a plurality of thin cathode supporting metal wires sandwiched and fixed in a crossed manner between the closed end surface of the metal sleeve and the bottom surface of the metal cup, A thin metal disk is interposed between the closed surface of the metal sleeve and the bottom surface of the metal cup, coaxially therewith, and provided with a plurality of grooves radiating from the center for inserting the intersecting thin metal wires for supporting the cathode. , the sleeve closing surface, the metal disk, and the bottom surface of the metal cup are welded and fixed.

[Effect]

If the above means is taken, the bottom surface of the metal cup, both surfaces of the metal disk, and the closed end surface of the metal sleeve are all flat, and when these are welded, the joint strength between the respective flat surfaces is extremely strong, and the metal disk The adhesion strength between the metal thin wire for cathode support inserted into the groove and each of the above members is extremely strong.
Since the closed surface of the metal sleeve, both sides of the metal disk, and the bottom surface of the metal cup are connected to each other in plane contact,
Thermal conductivity between the above-mentioned members is good, and the impregnated cathode pellet is always stably and efficiently heated by the heater, resulting in stable electron emission characteristics.

〔Example〕

FIG. 1 is a perspective view of an embodiment of the present invention, in which numeral 6 denotes a thin metal disk provided with radial grooves according to the present invention, and other symbols are the same as in FIG. 2. Also, Figure 3 shows the metal circle 51
6 is an enlarged perspective view of FIG.

On the closed end surface of the metal sleeve 3, a thin metal disk 6 made of a high melting point metal such as MO and having a diameter smaller than that of the sleeve and equal to or slightly larger than the outer diameter of the metal cup 2 is fixed coaxially with the sleeve by resistance welding or the like. has been done. This metal disk 6 has a thickness of about 100 μm at most and a width of 50 μm.
, grooves 6a, 6b+6c, and 6d each having a depth of about 50 μm are provided radially every 90 degrees. Also, a through hole 7 is provided in the center. The cathode support wire 5 is a tungsten wire with a diameter of 50 μm, one wire is in the grooves 6a and 6c, and the other wire is in the i6
The diameter of the center through hole 7 of the zero disc 6, which is fitted into the holes b and 6d and fixed by resistance welding or the like, is large enough to accommodate the criss-crossed portion of the two cathode support wires. Further, the bottom surface of the metal cup 2 is coaxially stacked and welded to the surface of the metal disk 6 on the opposite side from the sleeve. After the metal cup 2, metal disk 6, metal sleeve 3, and cathode support wire 5 are fixed together in this way, the impregnated cathode 1-, which is constructed in the same manner as before, is placed in the metal cup 2, and the two are placed together. Fixation by (e.g. laser) welding. Furthermore, the end of the cathode support wire 5 is welded and fixed to the end face of the cathode support cylinder which is fitted and supported in a through hole of a ceramic insulating substrate (not shown), and the heater 4 is inserted into the sleeve 3 to form an impregnated cathode. The structure is completed.

In this way, the cup 2 and the sleeve 3 can be directly joined on their planes via the metal disk 6, and the two support wires 5 are metal circles! Since it can be directly joined within the groove having the same diameter as the support wire provided in the support wire 16, the joining strength between each component is significantly improved. In addition, since the cup 2, the disk 6, and the sleeve 3 are joined in contact with each other on wide planes, the thermal conductivity between these members is good, and stable electron emission characteristics can be obtained.

The material of the metal disk 6 is the same as in the above embodiment.

However, the welding strength can be further improved by using Mo materials such as Re-Mo alloy, platinum plating, or platinum cladding. In addition, the metal disk 6 does not have to be integral, but has four fan-shaped pieces 6e, 6F, as shown in FIG.
6g or 6h may also be used.

〔Effect of the invention〕

As explained above, according to the present invention, the bonding strength between each component is significantly improved, heat conduction is improved, stable electron emission characteristics are obtained, and a highly reliable impregnated cathode structure is obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is a perspective view of an example of a conventional impregnated cathode structure using a thin cathode support wire, and FIG. 3 is an enlarged perspective view of a metal disk according to the present invention. , FIG. 4 is an explanatory diagram when a fan-shaped piece is used instead of a metal disk. 1--Impregnated cathode, 2--Metal cup, 3--Metal sleeve, 4-Heater, 5-Cathode support wire, 6
・-・Metal disk according to the present invention, 6a+6b+6c, 6
d-groove Fig. 1

Claims (1)

[Scope of Claims] 1. A metal sleeve with a built-in heater and closed at one end, a metal cup with bottoms attached back to back to the outside of the closed end of the metal sleeve, and a metal cup that is housed in the metal cup and receives electronic data from the open side of the cup. An impregnated cathode assembly comprising: an impregnated cathode that emits a metal sleeve; and a plurality of thin metal wires for supporting the cathode that are sandwiched and fixed in an intersecting manner between the closed end surface of the metal sleeve and the bottom surface of the metal cup; A thin metal disk having a plurality of grooves radiating from the center for inserting the intersecting thin metal wires for supporting the cathode is interposed coaxially between the surface and the bottom surface of the metal cup to close the sleeve. An impregnated cathode structure characterized by welding and fixing a surface, a metal disk, and a metal cup bottom. 2. The impregnated type according to claim 1, wherein the metal disk is provided with a central through hole for accommodating the thin metal wire intersection, and radial grooves located on two diameters orthogonal to each other in this through hole portion. Cathode structure.