JPH0680243U - Cathode structure - Google Patents

Abstract

(57) [Summary] [Purpose] The objective is to improve the thermal efficiency of the cathode assembly and increase its reliability. [Structure] The thickness of the portion of the cathode sleeve that does not overlap with the cathode pellet is made smaller than the thickness of the portion that does not overlap, or the thickness of the portion that does not overlap exceeds a predetermined thickness from the outer peripheral surface or the inner peripheral surface or both of them to the inside. An oxide layer was provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a cathode assembly of an impregnated cathode such as a cathode ray tube (CRT).

[0002]

[Prior art]

3 (a) and 3 (b) respectively show the structure of a conventional cathode assembly of this type, and FIG. 4 shows an example of the support structure of this type of cathode assembly. In the figure, 1 is an impregnated cathode pellet, 2 is a brazing filler metal, 3 is a cathode cap, 4 is a cathode sleeve, 5 is a sleeve support, 6 is a cathode base, and 7 is a heater. A conventional cathode assembly of this type is made of BaO, CaO, and Al ₂ O ₃ impregnated into porous tungsten having a porosity of 15 to 25%, which is obtained by heating tungsten powder to 2000 to 2500 ° C. in a reducing atmosphere and sintering. The impregnated cathode pellet 1 impregnated with the agent was brazed or welded to a cathode sleeve 4 (thickness of about 30 to 60 μm) having a uniform thickness. In the case of welding, the cathode pellet 1 is fitted into the cap 3, inserted into the cathode sleeve 4, and the upper ends of both are welded by resistance welding or laser welding. As shown in FIG. 4, the cathode structure is supported by a sleeve support 5 fixed to the cathode base 6, and the sleeve support 5 is attached by resistance welding. In order to obtain sufficient emission for operation from this cathode assembly, the cathode pellet 1 is heated to a temperature of about 1000 ° C. by the heat generated by the heater 7 inserted in the cathode sleeve 4 by applying a predetermined voltage to the other electrode. It is necessary to heat up.

[0003]

[Problems to be solved by the device]

 Conventionally, in this type of cathode assembly, when the cathode pellet is heated to a temperature of around 1000 ° C., a large amount of heat generated from the heater 7 is conducted to the cathode sleeve 4 and escapes to the sleeve support 5, resulting in poor thermal efficiency. Since the heater input power must be increased to raise the heater temperature, the leakage current between the heater cathodes increases, the risk of heater burnout increases, the life of the heater decreases, and reliability decreases. There was a problem of pulling. The present invention has been made to solve the above problems, and an object thereof is to improve thermal efficiency.

[0004]

[Means for Solving the Problems]

 In order to improve the thermal efficiency of the cathode assembly, the present invention makes the thickness of the portion of the cathode sleeve that does not overlap with the cathode pellet smaller than the thickness of the portion that overlaps by electrolytic polishing, or the portion that does not overlap with the cathode pellet of the cathode sleeve. An oxide layer having a predetermined thickness was formed from the outer peripheral surface, the inner peripheral surface, or both surfaces thereof to the inside of the thickness of the cathode sleeve to increase the heat conduction resistance of the cathode sleeve.

[0005]

[Action]

 With the above configuration, the amount of heat conducted through the cathode sleeve and escaping to the sleeve support is reduced, the thermal efficiency is increased, the input power of the heater can be reduced, and the problem of lowering reliability is solved.

[0006]

【Example】

 1 (a) and 1 (b) show an embodiment of claim 1 of the present invention, and FIGS. 2 (a) and 2 (b) show an embodiment of claim 2 of the present invention. In the figure, reference numerals 1, 2, and 3 are the same as or equivalent to those in FIG. 3, and 4a is a cathode sleeve in which the thickness of the portion not overlapping the cathode pellet 1 is thinner than the thickness of the overlapping portion by electrolytic polishing or the like. For example, the thickness of the non-overlapping portion is about 10 to 30 μm with respect to the overlapping portion of the thickness 30 to 60 μm. Reference numeral 4b denotes a cathode sleeve provided with an oxide layer 41b having a predetermined thickness from the outer peripheral surface of the portion which does not overlap with the cathode pellet 1 to the inner portion of the wall thickness. The oxide layer 41b can be easily formed by well-known anodic oxidation or the like. The heat generated from the heater 7 is partially transferred from the heater 7 directly to the cathode pellet 1, but most of the heat is transferred to the cathode pellet 1 through the cathode sleeves 4a and 4b. According to the structure shown in the embodiment, the amount of heat transmitted to the cathode support 4a, 4b and escaping to the sleeve support 5 is significantly reduced as compared with the conventional one, and the amount of heat transmitted from the heater 7 to the cathode pellet 1 via the cathode sleeve is increased. The thermal efficiency is improved, and it is possible to obtain the desired emission even if the input power of the heater is reduced compared with the conventional one. The leakage current between the heater and the cathode is reduced, the risk of heater burnout is eliminated, and the life of the heater is extended. .

Although FIG. 2 shows an example in which the oxide layer 41b is provided from the outer peripheral surface of the portion of the cathode sleeve 4b that does not overlap the cathode pellet 1 to the thick inside, it is provided from the inner peripheral surface to the thick inside. Alternatively, it may be provided from both sides to the inside of the thick wall.

[0008]

[Effect of device]

 As described above, according to the present invention, the thermal efficiency of the cathode assembly is increased, the heater input power need not be increased as much as in the conventional case, the heater temperature is lowered, the leakage current between the heater and the cathode is reduced, and the risk of heater burnout is reduced. Loss, the life of the heater is extended, and reliability is improved.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of claim 1 of the present invention.

FIG. 2 is a view showing an embodiment of claim 2 of the present invention.

FIG. 3 is a diagram showing the structure of a conventional cathode assembly of this type.

FIG. 4 is a diagram showing an example of a support structure for a cathode assembly of this type.

[Explanation of sign]

 1 cathode pellet 2 brazing material 3 cathode cap 4, 4a, 4b cathode sleeve 41b oxide layer 5 sleeve support 6 cathode base 7 heater

Claims (2)

[Scope of utility model registration request] 1. A cathode assembly, which is obtained by brazing an impregnated cathode pellet to a cathode sleeve or by fitting the cap sleeve into a cap sleeve, inserting the cathode sleeve into the cathode sleeve, and resistance-welding or laser-welding the both. A cathode assembly characterized in that the heat conduction resistance of the cathode sleeve is increased by making the thickness thinner than that of the overlapping portion. 2. A cathode structure in which an impregnated cathode pellet is brazed to a cathode sleeve or fitted into a cap, inserted into the cathode sleeve, and both are welded by resistance welding or laser welding. A cathode assembly, wherein the heat conduction resistance of the cathode sleeve is increased from the outer peripheral surface, the inner peripheral surface, or both surfaces of the non-exposed portion.