JPH07262906A - Impregnated type cathode structural body and cathode-ray tube using the same - Google Patents

Abstract

PURPOSE:To obtain a reliable impregnated-type cathode structural body having its excellent and stable electron emission characteristics for a long time under the high-density current using condition and a cathode-ray tube using this cathode structural body. CONSTITUTION:At least such components are provided, as a cathode pellet 1 having a coating film 103 made of metals of one or two sorts or more of ruthenium, osmium, and tungsten, or their alloys on the electron emitting surface of a high melting-point, porous base metal 101 in which an electron emitting substance 102 made of polygenic oxides including barium oxide is impregnated, and a high melting-point sleeve 4 in which a heater 8 for heating the cathode pellet is included. The thickness of the coating film 103 provided on the electron emission surface of the cathode pellet is determined within the range from 50nm or more to less than 300nm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube such as a projection type cathode ray tube or a television cathode ray tube.
Even if an electron beam with a high current density of about 0 A / cm ² is used under a high anode voltage, a high-quality image with extremely high brightness can be obtained in the early stages, of course, and with high performance. The present invention relates to a cathode ray tube using a highly reliable impregnated cathode structure.

[0002]

2. Description of the Related Art A cathode ray tube of this type comprises a vacuum tube comprising a panel tube coated with a phosphor, a neck for accommodating an electron gun, and a funnel connecting the panel and the panel with the neck. To be done.

FIG. 6 is a partial sectional view of a shadow mask type color cathode ray tube for explaining an example of the structure of the cathode ray tube.
61 is a panel, 62 is a neck, 63 is a funnel, 64
Is a fluorescent screen, 65 is a shadow mask having a large number of electron beam passage holes, 66 is a mask frame, 67 is a magnetic shield, 68 is a shadow mask suspension mechanism, 9 is three electron beams Bc (center electron beam), Bs ( An electron gun for emitting two side electron beams), a deflection yoke 70 for deflecting the electron beams horizontally and vertically, and an external magnetic device 71 for purity correction and the like.

In the figure, a panel 61 and a funnel 63 having an inner surface coated with a phosphor 64 are a shadow mask 6 inside a bulb formed by the panel 61 and the funnel 63.
5, the mask frame 66 to which the magnetic shield 67 and the like are fixed is mounted by the shadow mask suspension mechanism 68, and the neck 6
The electron gun 69 is enclosed in the column 2, welded and fixed with frit glass, and vacuum-sealed at the neck 64.

An electron beam R emitted from the electron gun 4,
G and B are deflected in two directions, horizontal and vertical, by a deflection yoke 7 attached to the transition portion of the neck 4 and the funnel 2, and form a fluorescent screen through an electron beam passage hole of a shadow mask 5 which is a color selection electrode. An image is formed by striking a phosphor of a predetermined color.

FIG. 7 is a side view for explaining an example of the structure of an electron gun used in this type of cathode ray tube. 18 is a cathode structure, 19 is a first electrode, 20 is a second electrode, and 21 is a third electrode. , 22 is a fourth electrode, 23 is a fifth electrode, 24 is a sixth electrode, 25 is a beading glass, and 26 is a stem pin.

In the figure, the cathode structure 18, the first electrode 19, the second electrode 20, the third electrode 21, the fourth electrode 22,
The fifth electrode 23 and the sixth electrode 24 are coaxially fixed by a pair of beading glasses 25.

The electron beam emitted from the cathode structure 18 has a first electrode 19, a second electrode 20, a third electrode 21, and a fourth electrode.
The electrodes 22, the fifth electrode 23, and the sixth electrode 24 receive the required acceleration and focusing, and the light is emitted from the sixth electrode 24 in the fluorescent screen direction. The stem pin 26 is a terminal for applying a voltage and an image signal required for a predetermined electrode forming the electron gun.

A so-called impregnated cathode structure is known as a kind of cathode structure constituting an electron gun used in the above-mentioned cathode ray tube. This impregnated cathode structure is suitable for a cathode having a high current density, and a porous base metal of tungsten, which is one of refractory metals, and barium (Ba),
One using a cathode pellet impregnated with an electron emitting substance composed of a ternary oxide of calcium (Ca) and aluminum (Al), and an electron emitting surface of the cathode pellet for further improving electron emitting characteristics. There is one coated with osmium (Os), ruthenium (Ru), or an alloy thin film thereof.

The alloy thin film has a thickness of 500-80.
It is generally 0 nm (for example, Japanese Patent Laid-Open No. 4-2
48223 and JP-A-4-259727).

[0011]

Such an impregnated type cathode assembly can provide stable high current density and stable operation for a long time, but the initial current characteristics are unstable. There is also a problem that the electron emission life is short.

[0012] One of the causes is a remarkable evaporation fluctuation of the electron emitting material due to a temperature fluctuation at a high temperature such that the cathode assembly temperature required to obtain a high density current is 1000 ° C surplus. The change in the depletion arrival time of the electron-emitting substance, etc. accompanying this can be mentioned.

However, according to the research conducted by the present inventors, the thickness of the coating film provided on the electron emission surface of the cathode pellet significantly deteriorates the electron emission ability, and the initial current characteristics of the cathode structure are impaired. Stabilized, and found that some of them had a very early end of life triggered by this.

Further, it has been found that the characteristics of the cathode ray tube using this cathode structure are also made unstable.

As described above, in the conventional impregnated cathode structure, the film thickness of the coating film provided on the electron emission surface of the cathode pellet is generally 500 to 800 nm, and the initial stage of the cathode structure. The current characteristics are made unstable and the reliability thereof is lowered, and the characteristics of the cathode ray tube using the same are also made unstable and the reliability is lowered.

The object of the present invention is to solve the above-mentioned problems of the prior art, and not only the initial current characteristics but also good and stable even when used for a long time under the use condition of a high density current of about 10 A / cm ^2. An object of the present invention is to provide a highly reliable impregnated cathode structure having excellent electron emission characteristics and a cathode ray tube using this cathode structure.

[0017]

In order to achieve the above object, the present invention provides a refractory porous base metal impregnated with an electron emitting substance composed of a multi-component oxide containing barium oxide, and the refractory porous base metal. Includes a cathode pellet having a coating film made of one or more of ruthenium, osmium and tungsten, or an alloy thereof on the electron emission surface of the metal, and a heater for heating the cathode pellet. In the impregnated cathode structure, the thickness of the coating film on the electron emission surface of the cathode pellet is 5
It is characterized in that the range is from 0 nm to 300 nm.

Further, the present invention is characterized in that the high melting point porous base metal is mainly composed of one kind or two or more kinds selected from tungsten, molybdenum and nickel. And, the present invention is a refractory porous base metal impregnated with an electron emitting substance comprising a multi-component oxide containing barium oxide, and ruthenium, osmium, or a kind of tungsten on the electron emitting surface of the refractory porous base metal, Alternatively, at least a cathode pellet having a coating film made of two or more kinds of metals or alloys thereof and a high melting point sleeve containing a heater for heating the cathode pellet are provided, and the electron of the cathode pellet is provided. It is characterized in that the coating film provided on the emission surface is provided with an impregnated cathode structure in which the thickness is in the range of 50 nm to 300 nm.

[0019]

The impregnated cathode assembly having the above-described structure has a good initial current characteristic, and a stable electron emission characteristic can be obtained for a long time even under a condition of using a high density current of about 10 A / cm ² .

The cathode ray tube equipped with the electron gun using the impregnated cathode structure of this construction maintains stable characteristics for a long time.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a sectional view for explaining an embodiment of an impregnated cathode structure according to the present invention, in which 1 is a cathode pellet, 2 is a bottomed cup, 3 is a rhenium-tungsten wire, and 4 is a sleeve. 5 is an eyelet, 6 is crystallized glass, 7 is a support, and 8 is a heater. Also, 101
Is a tungsten porous sintered body, 102 is an impregnated electron emission material, and 103 is an alloy coating film.

The cathode pellet 1 is made of barium (B
a), a porous tungsten sintered body 101 impregnated with an electron emitting substance 102 composed of a ternary oxide of a), calcium (Ca), and aluminum (Al), and osmium (Os) on the surface (electron emitting surface). A ruthenium (Ru) alloy coating film 103 is provided.

The bottomed cup 2 accommodates the cathode pellet 1 described above, and the bottomed cylindrical sleeve 4 made of molybdenum (Mo) has a heater 8 for heating the cathode pellet 1 from below the bottomed cup 2. To include.

Two orthogonal rhenium-tungsten wires 3 are mounted between the bottomed cup 2 and the sleeve 4 which are fixed by welding to each other so as to suspend them and support them while suppressing heat loss. .

Each end of the two rhenium-tungsten wires 3 is iron (Fe) -nickel (Ni) -cobalt (Co).
The eyelet 5 is supported by a crystallized glass 6 as a heat insulating and insulating member, and is assembled into an electron gun assembly through a support 7 made of iron (Fe) -nickel (Ni). To be

The tungsten porous sintered body 101 is formed by granulating tungsten metal powder having an average particle diameter of 5 μm at a predetermined pressure, temporarily firing it in a hydrogen gas atmosphere, and further at 1950 ° in a high vacuum. It was sintered at a high temperature of C for 2 hours to finish it into a cylindrical shape having an outer diameter of 1.3 mm and a thickness of 0.55 mm to obtain a base metal. The porosity of the tungsten porous sintered body 101, which is the porous base metal, is 20%.

Next, the above-mentioned tungsten porous sintered body 1
In the hole of No. 01, barium oxide (BaO), calcium oxide (CaO), and aluminum oxide (Al ₂ O ₃ ) were prepared so as to have a molar ratio of 4: 1: 1. It is melted and impregnated into the impregnated electron emission material 102.

Then, the excess electron emission material attached around the tungsten porous sintered body 101 is removed to obtain the cathode pellet 1.

Next, two rhenium-tungsten (Re
-W) Wire 3 with 0.05 mm thick molybdenum (Mo)
The bottomed cup 2 having an inner diameter of 1.3 mm and a total height of 0.5 mm and having a bottom, and a sleeve 4 made of Mo material having a thickness of 0.1 mm and having a bottom on the top surface are crossed in a cross shape. In addition, these three are electric resistance welding, laser welding,
Weld together by electron beam welding.

The cathode pellet 1 accommodated and inserted in the bottomed cup has the impregnated electron emitting material 102 in the tungsten porous sintered body 101 as described above, and the electron emitting surface thereof is 80% osmium. A (Os) -20% ruthenium (Ru) alloy coating film 103 is formed to a thickness of 150 nm by a sputtering method.

The cathode pellet 1 is mounted on the bottomed cup 2 by using a known pressure charging machine having a pair of vertically movable movable rods and a fixed rod (not shown). Is pressed into the bottomed cup 2 and the side surface of the cup 2 is squeezed and fixed.

The integrated assembly having the cathode pellet 1 with the osmium-ruthenium alloy coating film 103 obtained as described above is held on the crystallized glass 6 having the supporting band 7 by iron (Fe)-. The impregnated cathode assembly is constructed by mounting the nickel (Ni) -cobalt (Co) eyelet 5 by laser welding or the like, and inserting and fixing the heater 8 for heating in the sleeve 4.

The structure of the above cathode structure is already known, and detailed description of the structure is omitted. Also, the alloy coating film 1
No. 03 is not limited to the above-described sputtering method, and for example, a vacuum vapor deposition method or an electron beam method may be used, but the sputtering method is preferable because of the advantage of high film-forming density.

FIG. 2 is an enlarged sectional view of a neck portion of a projection type cathode ray tube as an example of a cathode ray tube having the impregnated cathode structure according to the present invention, in which 1 is a cathode pellet, 8 is a heater, and 13 is a neck. , 18 is a cathode structure,
19 is a first electrode, 20 is a second electrode, 21 is a third electrode, 2
5 is a beading glass and 26 is a stem pin.

In the figure, the heater 8 causes about 100
The first electrode 19 and the second electrode 2 which face the cathode assembly 18 heated to 0 ° C. and focus and control the electron beam
0, the third electrode 21 and the like are coaxially provided with a beading glass 25 at a predetermined interval.

The stem pin 26 is a terminal for supplying a required voltage except the anode voltage and an image signal to the electron gun.

In the projection type cathode ray tube having this structure, the heater 8
Is 6.3V, the cathode structure 18 is 190V, the first electrode 19 is ground potential, and the second electrode 20 is 700V.
˜800 V is applied to the third electrode 21 for acceleration focusing and the fifth electrode (not shown), and 30 kV is applied to the fourth electrode (not shown).

FIG. 3 is an explanatory diagram of the electron emission stabilizing effect of the impregnated cathode structure according to the present invention, in which the horizontal axis represents the voltage Ef (V) applied to the heater contained in the sleeve and the vertical axis represents the heater voltage. Maximum anode current I (μA) of the corresponding cathode ray tube
Is.

In the figure, a curve M ₁ is a cathode ray tube mounted with an impregnated cathode structure provided with a coating film according to the present invention,
A curve L ₁ is a plot of maximum anode currents of a cathode ray tube having an impregnated cathode structure provided with a coating film according to the prior art, corresponding to changes in heater voltage.

As is clear from the figure, the heater voltage Ef
In particular, in the low voltage region, the stability of the initial current characteristic is remarkably different between the curve M ₁ and the curve L ₁ .

That is, in the case of the curve M ₁ , the anode current has a fluctuation durability more than twice as high as that of the curve L ₁ with respect to the low output fluctuation of the heater voltage, which is the electron of the cathode pellet according to the present invention. The release profile is stable.

FIG. 4 is an explanatory view of the long-term electron emission stabilizing effect of the projection type cathode ray tube in which the impregnated cathode structure according to the present invention is mounted. The horizontal axis represents the operating time T (kh) and the vertical axis represents the maximum anode current. It is a ratio (%).

M ₂ and L ₂ are heated by a heater so that the operating temperatures of the cathode pellets of the cathode ray tube corresponding to the curves M ₁ and L ₁ in FIG. 3 are the same, and the cathode ray tube at that time is heated. The relationship between the anode current and the forced life time of is determined experimentally. In this case, the temperature was forced to be 8 times the standard use condition of the current density of 10 A / cm ² .

From the figure, the characteristic curve M ₂ of the cathode ray tube in which the cathode structure according to the present invention is mounted is higher than that of the conventional characteristic curve L ₂ in terms of high density current emission, stable for a long time and stable. It is clear that it has the characteristics described above.

FIG. 5 is an explanatory view of the electron emission characteristic effect at low temperature of the impregnated cathode structure according to the present invention, in which the horizontal axis represents the film thickness D (n) of osmium (Os) / ruthenium (Ru).
m), and the vertical axis represents the anode current ratio (%) of the cathode ray tube.

In the figure, the osmium (Os) / ruthenium (R) coating on the electron emission surface of the cathode pellet is shown.
u) When the film thickness D (nm) of the coating film exceeds 300 nm,
It can be seen that the anode current ratio in the low voltage region is significantly reduced.

The film thickness D (nm) of the coating film is 50.
When the thickness is less than nm, the film thickness is too thin, which shortens the life.

From the above, in the cathode structure according to the present invention, the thickness of the coating film is 50 nm or more and 300 n or less.
The range is within m.

As described above, in the embodiment of the present invention, the thickness of the coating film formed on the electron emission surface of the impregnated cathode pellets constituting the cathode assembly is 50 nm or more and 300 n or less.
By setting the range within m, stable initial current characteristics can be obtained, and stable electron emission performance can be maintained even after long-term use.

In the above-mentioned projection type cathode ray tube having this cathode structure mounted, the electron emission capability is remarkably lowered during use, resulting in a dark screen, or in the worst case, no output occurs. In addition, it is possible to provide a highly reliable cathode ray tube capable of stably obtaining a high-luminance screen comparable to a direct-viewing type cathode ray tube with an electron beam having a large current density for a long period of time.

Of course, not only the projection type cathode ray tube but also the direct view type cathode ray tube can obtain the same effects as the above.

[0053]

As described above, according to the present invention,
While ensuring sufficient electron emission capacity to obtain high current density,
In addition to stable initial high current characteristics, it is possible to provide a highly reliable impregnated cathode structure that enables stable operation for a long time and a highly reliable cathode ray tube by mounting this cathode structure. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating one example of an impregnated cathode structure according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a neck portion of a projection type cathode ray tube as an example of a cathode ray tube on which an impregnated cathode structure according to the present invention is mounted.

FIG. 3 is an explanatory diagram of an electron emission stabilizing effect of the impregnated cathode structure according to the present invention.

FIG. 4 is an explanatory view of a long-term electron emission stabilizing effect of a projection type cathode ray tube in which an impregnated cathode structure according to the present invention is mounted.

FIG. 5 is an explanatory diagram of an electron emission characteristic effect at a low temperature of the impregnated cathode structure according to the present invention.

FIG. 6 is a partial cross-sectional view of a shadow mask type color cathode ray tube for explaining an example of the structure of the cathode ray tube.

FIG. 7 is a side view illustrating a structural example of an electron gun used in this type of cathode ray tube.

[Explanation of symbols]

 1 Cathode / Pellet 2 Bottomed Cup 3 Rhenium-Tungsten Wire 4 Sleeve 5 Eyelet 6 Crystallized Glass 7 Support 8 Heater 13 Neck 18 Cathode Structure 19 First Electrode 20 Second Electrode 21 Third Electrode 25 Beading Glass 26 Stem Pin 101 Porous tungsten sintered body 102 Impregnated electron emission material 103 Alloy coating film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadanori Taguchi 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. Electronic Device Division

Claims (3)

[Claims] 1. A refractory porous base metal impregnated with an electron emitting substance composed of a multi-element oxide containing barium oxide, and one of ruthenium, osmium and tungsten on the electron emitting surface of the refractory porous base metal, or Two or more metals,
Alternatively, in an impregnated cathode structure including at least a cathode pellet having a coating film made of these alloys, and a high melting point sleeve including a heater for heating the cathode pellet, the electron emitting surface of the cathode pellet An impregnated-type cathode assembly, wherein the thickness of the coating film provided above is in the range of 50 nm to 300 nm. 2. The impregnated cathode structure according to claim 1, wherein the high melting point porous base metal is mainly composed of one kind or two or more kinds selected from tungsten, molybdenum and nickel. 3. A refractory porous base metal impregnated with an electron emitting substance composed of a multi-component oxide containing barium oxide, and one of ruthenium, osmium and tungsten on the electron emitting surface of the refractory porous base metal, or Two or more metals,
Alternatively, at least a cathode pellet having a coating film made of these alloys and a high melting point sleeve containing a heater for heating the cathode pellet are provided, and the target to be coated on the electron emitting surface of the cathode pellet is provided. A cathode ray tube comprising an impregnated cathode assembly having a thickness of a covering film in a range of 50 nm to 300 nm.