JPH11224592A - Impregnated cathode structural body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impregnated cathode structural body which enhances mass productivity as well as reducing thermal conduction loss. SOLUTION: In an impregnated cathode structural body 1, an end part of a cathode sleeve 2 is blocked by a recessed part 3 with a recessed surface facing upward. A side of the cathode sleeve 2 blocked by the recessed part 3 is formed by a thickness part 2a and its lower part is formed by a thickness part 2b. A cathode base body 5 having an electron irradiating surface impregnated with electron irradiating material as an upper surface is fixed in the recessed part 3, and a heater to heat the cathode base body 5 is arranged in the cathode sleeve 2. A cylindrical holder 7 is arranged by a cathode supporter 10 on the same axis as one for the cathode sleeve 2 outside the cathode sleeve 2. When the heater is ignited, since a quantity of heat in the cathode sleeve 2 gets bigger in the thickness part 2 a side with a thicker cross section, it is concentrated in the blocking side of the cathode sleeve 2, and since the concentrated heat is thermally conducted to the cathode base body 5 with the cathode sleeve 2 fixed by fusing, heating efficiency of the cathode base body 5 is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impregnated-type cathode structure for reducing power consumption.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for a color picture tube, a large color picture tube or a high-definition display tube having an increased number of scanning lines and improved resolution. These tubes use an impregnated-type cathode assembly capable of obtaining electron emission with a larger current density than an oxide cathode.

However, the operating temperature of the impregnated type cathode assembly is higher than that of the oxide cathode, and the constituent material is generally made of a high melting point metal, which causes high cost.

Here, a conventional impregnated cathode assembly will be described with reference to FIG.

[0005] The impregnated cathode assembly 1 shown in FIG. 3 is a tube made of a metal such as tantalum (Ta), niobium (Nb), molybdenum (Mo), rhenium (Re), or an alloy thereof, having open ends. -Shaped cathode sleeve 2,
One end of the cathode sleeve 2 is closed by a concave portion 3 whose concave surface faces upward, and a convex portion 4 protruding upward is formed on the bottom surface of the concave portion 3. In the concave portion 3, an electron emitting surface in which porous tungsten having a porosity of about 20% is impregnated with an electron emitting material such as barium oxide (4BaO), calcium oxide (CaO), and aluminum oxide (Al ₂ O ₃ ). Is fixed in a state of being substantially flush with or slightly protruding from the upper surface, and a heater (not shown) for heating the cathode substrate 5 is provided in the cathode sleeve 2. A ruthenium (Ru) -molybdenum (Mo) brazing material layer 6 is formed on the lower surface of the cathode base 5 on the side of the recess 3, and the cathode base 5 is positioned so that the brazing layer 6 is located on the bottom surface of the recess 3. Brazing has been fixed.

On the outside of the cathode sleeve 2, a cylindrical holder 7 is disposed coaxially with the cathode sleeve 2 so as to surround the cathode sleeve 2 while maintaining a predetermined distance from the outer peripheral surface. An opening 8 is formed on the upper surface of the cathode sleeve 2. A plurality of, for example, three, strip-shaped cathode supports 10 made of the same material as the cathode sleeve 2 are formed on a shoulder 9 formed around the opening 8.
The cathode sleeve 2 is held by the cathode support 10.

[0007]

However, the conventional impregnated cathode assembly 1 shown in FIG. 3 is not only made of a high-melting-point metal, but also is a very small part. Need technology.

In recent years, the impregnated cathode assembly 1 has been required to operate at a low power. In the structure shown in FIG. 3, since the cathode sleeve 2 absorbs heat from the heater, the temperature is maintained at a constant heater voltage. There is a limit to the power saving of the heater power required for this.

Furthermore, since the cross-sectional thickness of the cathode sleeve 2 is uniform, the amount of heat of the cathode sleeve 2 heated by the heater is dispersed, so that the cathode base 5 cannot be efficiently heated and the lower end side of the cathode sleeve 2 is opened. From cathode support 9
The problem is that the heat conduction loss to the heat is large.

[0010] The present invention has been made in view of the above problems, and has as its object to provide an impregnated cathode assembly having reduced heat conduction loss and improved mass productivity.

[0011]

According to the present invention, there is provided a cathode substrate impregnated with an electron-emitting substance, the cathode substrate being attached at one end, and having a thermal conductivity at the other end at which the cathode substrate is attached. A cathode sleeve formed with a conductivity higher than the thermal conductivity, and the heat conductivity of the side of the cathode sleeve to which the cathode base is attached is higher than the heat conductivity of the other end, so that the cathode base is efficiently provided. Can be heated, so that heat conduction loss is reduced.

The thickness of the cathode sleeve on the side to which the cathode base is attached is formed to be greater than the thickness of the other end side, and the thermal conductivity differs with a simple configuration due to the difference in thickness. .

Further, the thickness of the cathode sleeve on the side where the cathode base is attached is 1.5 to 3 times the thickness on the other end side.
It is twice as large, and the thermal conductivity is made appropriate within a range where formation is possible.

Further, since the cathode sleeve has a substantially concave portion to which the cathode base is attached,
The cathode base can be efficiently heated.

The other end of the cathode sleeve opposite to the portion to which the cathode base is attached is formed in a flared shape, so that a heater can be easily inserted into the cathode sleeve.
Insulation failure of the heater is reduced.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the impregnated cathode structure of the present invention will be described below with reference to the drawings. The parts corresponding to the conventional example shown in FIG.

The impregnated cathode assembly 1 shown in FIG. 1 has a cylindrical shape made of a metal such as tantalum (Ta), niobium (Nb), molybdenum (Mo), rhenium (Re), or an alloy thereof, with open ends. One end of the cathode sleeve 2 is closed by a concave portion 3 having a concave surface facing upward, and the bottom surface of the concave portion 3 is formed with a convex portion 4 protruding upward and convex. . The cathode sleeve 2 has a thick portion 2a formed on the side closed by the concave portion 3, and an open portion slightly below the middle has a thin portion 2b thinner than the thick portion 2a, and a thick portion 2a. A sakai portion 2c is formed between the thin portion 2b and the thin portion 2b. The thick portion 2a is formed to be 1.5 to 3 times as thick as the thin portion 2b. Further, in the concave portion 3, an electron emission surface in which porous tungsten having a porosity of about 20% is impregnated with an electron emission material such as barium oxide (4BaO), calcium oxide (CaO), and aluminum oxide (Al ₂ O ₃ ). Is fixed in a state of being substantially flush with or slightly protruding from the upper surface, and a heater (not shown) for heating the cathode substrate 5 is provided in the cathode sleeve 2. A brazing material layer 6 of ruthenium (Ru) -molybdenum (Mo) is formed on the lower surface of the cathode base 5 on the side of the recess 3, and the cathode base 5 is soldered such that the brazing layer 6 is located on the bottom surface of the recess 3. It is fixed.

On the outside of the cathode sleeve 2, a cylindrical holder 7 is disposed coaxially with the cathode sleeve 2 so as to surround the cathode sleeve 2 while maintaining a predetermined distance from the outer peripheral surface. An opening 8 is formed on the upper surface of the cathode sleeve 2. A plurality of, for example, three, strip-shaped cathode supports 10 made of the same material as the cathode sleeve 2 are formed on a shoulder 9 formed around the opening 8.
The cathode sleeve 2 is held by the cathode support 10.

Here, a method of manufacturing the cathode sleeve 2 will be described.

For example, if the thickness of the cathode sleeve 2 is 0.25
A circular plate is punched out of a tantalum plate having a thickness of 2 mm, and the drawing process is repeated until the disk has a predetermined outer diameter.

Next, the cathode sleeve 2 is trimmed so that the entire length thereof becomes a predetermined size, the concave portion 3 is formed in the closed portion of the cathode sleeve 2, and the convex portion 4 is formed on the bottom surface of the concave portion 3.

Further, a boundary portion 2c having a cross-sectional thickness is formed on the side surface of the cathode sleeve 2 to form the thick portion 2a and the thin portion 2b. It is desirable to anneal in an intermediate step because the fracture is likely to occur.

Although the material of the cathode sleeve 2 has been described as tantalum, niobium or tantalum-niobium (Ta) is used.
In the case of -Nb) alloy, it can be processed and welded in almost the same manner as in the case of tantalum, and in the case of molybdenum, rhenium and rhenium-molybdenum (Re-Mo) alloy, it can be formed by heating during processing of the cathode sleeve 2. .

According to the above-described embodiment, the amount of heat of the cathode sleeve 2 when the heater is ignited increases on the side of the thick portion 2a having a large cross-sectional thickness. Cathode substrate 5 with 2 fixed by melting
Since the heat is conducted to the cathode base 5, the heating efficiency of the cathode base 5 is increased.
On the other hand, the open side of the cathode sleeve 2 is a thin portion having a small cross-sectional pressure.
Since it is 2b, heat does not concentrate, so that heat is not conducted from the cathode support 10 to the cylindrical holder 7 that does not need to move heat, and the heating efficiency is increased. For example, the heater power required to maintain the temperature of the cathode base 5 at 1000 ° C. when the voltage of the heater is 6.3 V can be reduced from 1.3 W to 1.0 W. Further, when the cross-sectional thickness difference between the thick portion 2a and the thin portion 2b of the cathode sleeve 2 is less than 1.5 times, the current is 1.3 W, which does not lead to a reduction in the power of the heater. Conversely, molding is impossible with a cross-sectional thickness difference of 3.0 times. The boundary 2c of the cross-sectional thickness of the cathode sleeve 2 may be located at any position as long as it is a side surface.

In the above embodiment, the shape of the concave portion 3 of the cathode sleeve 2 is shown as having a gap between the inner wall of the cathode sleeve 2 and the outer wall of the concave portion 3. The same effect cannot be obtained even when the shape of both the recess 2 and the recess 3 is in contact with each other.

Next, another embodiment will be described with reference to FIG.

The embodiment shown in FIG. 2 is different from the embodiment shown in FIG. 1 in that a flare portion 2d which expands downward is formed at an open portion at the lower end of the cathode sleeve 2. When assembling the impregnated cathode assembly by inserting a heater into the heater, the heater is easily inserted, and insulation failure of the heater is eliminated.

[0028]

According to the present invention, the thermal conductivity of the side of the cathode sleeve on which the cathode substrate is mounted is higher than the thermal conductivity of the other end. And power consumption can be reduced with a simple configuration.

Further, since the thickness of the cathode sleeve on the side where the cathode substrate is mounted is formed thicker than the thickness on the other end side, it is possible to make the thermal conductivity different with a simple configuration due to the difference in thickness. it can.

Further, the cathode sleeve has a thickness on the side where the cathode substrate is mounted is 1.5 to 3 times the thickness on the other end side, so that the thermal conductivity is appropriately adjusted within a range where it can be formed. it can.

Further, the cathode sleeve has a substantially concave portion where the cathode base is attached, so that the cathode base can be efficiently heated.

Further, since the other end of the cathode sleeve opposite to the portion to which the cathode base is attached is formed in a flared shape, the heater can be easily inserted into the cathode sleeve, and the insulation failure of the heater can be reduced.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view showing one embodiment of an impregnated cathode structure of the present invention.

FIG. 2 is a partially cut-away side view showing an impregnated cathode structure according to another embodiment of the present invention.

FIG. 3 is a partially cutaway side view showing a conventional impregnated cathode assembly.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Impregnation type cathode structure 2 Cathode sleeve 5 Cathode base

Claims (5)

[Claims] 1. A cathode substrate impregnated with an electron emitting substance, said cathode substrate being attached at one end, and having a higher thermal conductivity on the side to which said cathode substrate is attached than the other end. An impregnated cathode structure comprising: a formed cathode sleeve. 2. The impregnated cathode assembly according to claim 1, wherein the thickness of the cathode sleeve on the side to which the cathode base is attached is formed larger than the thickness on the other end side. 3. The impregnated cathode assembly according to claim 2, wherein the thickness of the cathode sleeve on the side to which the cathode base is attached is 1.5 to 3 times the thickness on the other end side. . 4. The impregnated cathode assembly according to claim 1, wherein a portion of the cathode sleeve to which the cathode base is attached is formed in a substantially concave shape. 5. The impregnated cathode assembly according to claim 1, wherein the other end of the cathode sleeve opposite to the portion to which the cathode base is attached is formed in a flare shape.