JPH1092329A - Cathode body structure of cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the cathode body structure of a cathode-ray tube, capable of maintaining heating temperature for an electron emitting material layer at relatively high precision and inexpensively, and also giving no stress to the insulating layer of a heater core wire. SOLUTION: In the cathode body structure of a cathode-ray tube composed of a metallic sleeve 13, a metallic base body 14, wherein an electron emitting material layer 15 is coated on the surface, a heater 16, internally inserted to be retained by the sleeve 13, and a heater support 19: having a nearly U-shaped cross section joined to an end part of an electrode supporting body 21 fixedly arranged in an electron gun and of the heater 16, the heater support 19 is constituted by laminating plural metallic material 19a and 19b different in thermal expansion coefficient, where plural metallic materials 19a and 19b and their laminating condition are selected so that an interval S between the base body 14 and the heater 16 facing the base body 14 can be expanded when the temperature of the heater support 19 is increased during the operation of the cathode-ray tube.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode structure of a cathode ray tube, and more particularly, to an arrangement in which a space between a metal substrate and a heater opposed to the metal substrate is almost always maintained even when the temperature of the cathode structure increases during operation of the cathode ray tube. The present invention relates to a cathode structure of a cathode ray tube which can be kept constant.

[0002]

2. Description of the Related Art Generally, in a cathode ray tube such as a color picture tube used for a television receiver or a monitor color picture tube used for a display, a metal sleeve containing a heater is fitted to one end of the metal sleeve, and the surface of the metal sleeve is attached to the surface. An indirectly heated cathode structure including a cap-shaped metal substrate or the like on which an electron emitting material layer is adhered is used.

FIG. 4 is a sectional view showing an example of the configuration of such a known indirectly heated cathode assembly.

As shown in FIG. 4, an indirectly heated cathode 40 includes at least a cylindrical metal sleeve 41 made of a refractory metal such as nichrome, a cap-shaped metal base 42 made of the same refractory metal, for example, nickel, and Holds an electron emitting material layer 43, a heater core wire 44, an insulating layer 45 of alumina or the like, a dark coat covering layer 46 of tungsten fine powder or the like, a pair of substantially U-shaped heater supports 47, and a metal sleeve 41. And an electrode support 49 fixed to the electron gun of the cathode ray tube.

[0005] The cylindrical metal sleeve 41 has a cap-shaped metal base 42 fitted at one end and a metal sleeve receiver 48 at the other end. Cap-shaped metal base 42
Has an electron-emitting material layer 43 on the surface. The surface of the heater core wire 44 is covered with an insulating layer 45, and a dark coat covering layer 46 for improving heat radiation efficiency is covered thereon, and a central portion is inserted into the metal sleeve 41. The pair of heater supports 47 has one side of a substantially U-shaped cross section welded to the electrode support 49, and the other side of the substantially U-shaped cross section is welded to a corresponding end of the heater core wire 44. Have been.

In this case, when heating power is supplied to the heater core wire 44 through the pair of heater supports 47, the heater core wire 44 generates heat, and the heat is transmitted to the metal sleeve 41 and the metal base 42, and then the electron emission material layer 43 is formed. Conveyed to
Thermionic electrons are emitted from the electron emitting material layer 43.

[0007]

In such an indirectly heated cathode structure, in order to maintain a predetermined amount of thermionic emission from the electron emitting material layer 43, the heating temperature of the electron emitting material layer 43 is kept almost constant. Need to be retained. In this case, the heating temperature of the electron emitting material layer 43 is determined by the distance (gap) S between the metal base 42 and the heater core wire 44 facing the metal base 42.
The heater core wire 44 and the metal sleeve 41.
If the interval S is too large when the electron emitting material layer 43 is inserted and fixed, the heating value of the heater core wire 44 is not sufficiently transmitted to the electron emitting material layer 43, so that the electron emitting material layer 43 does not reach a predetermined heating temperature. On the other hand, when the interval S is too small and almost in contact with the heater core 44, the heater core 4 facing the metal base 42
4 is pressed against the metal base 42, stress is applied to the alumina insulating layer 45 covering the heater core wire 44, and cracks occur in the insulating layer 45.

Therefore, in the conventional indirectly heated cathode structure, the distance S between the metal base 42 and the heater core wire 44 facing the metal base 42 is set to a predetermined value, and the temperature of the electron emitting material layer 43 is reduced. In order to keep the heating temperature at a predetermined value and reduce the stress applied to the insulating layer 45 of the heater core wire 44 to prevent the insulating layer 45 from cracking,
Several means have already been proposed.

The first means is disclosed in Japanese Utility Model Laid-Open Publication No. 3-10456.
In order to accurately set the distance between the metal base and the heater facing the metal base to a predetermined value, the positioning projection is used as a guide. After the heater is positioned, that is, the interval is set to a predetermined value, the heater is fixed to the heater support by welding.

The second means is disclosed in JP-A-63-8 / 1988.
No. 1728 (Title of Invention: Method of Manufacturing Indirectly Heated Cathode Assembly) In order to properly set the distance between a metal substrate and a heater opposed to the metal substrate, pyrolysis is performed in the vicinity of the cathode assembly. A substance is provided, the interval is set to a predetermined value using the pyrolysis substance as a guide, and the pyrolysis substance is removed in a subsequent cathode ray tube manufacturing process.

However, in the first means, when the positioning projections are provided, it is difficult to set the distance between the metal base and the heater opposed to the metal base to a predetermined value due to a variation in the installation accuracy of the projections. In addition, when it is attempted to increase the accuracy of setting the projections, there is a problem that the installation requires a lot of cost.

Further, the second means has a problem that, in the process of manufacturing the cathode ray tube, when removing the pyrolysis material, the gas emitted from the pyrolysis material adversely affects the characteristics of the electron emitting material layer. have.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to maintain the heating temperature of the electron emitting material layer at a predetermined value with relatively high accuracy and at low cost.
An object of the present invention is to provide a cathode structure of a cathode ray tube which does not give stress to an insulating layer of a heater core wire.

[0014]

In order to achieve the above object, a cathode structure of a cathode ray tube according to the present invention is characterized in that a heater support is bonded to a plurality of metallic materials having different coefficients of thermal expansion, that is, displaced by heat. Means made of a bimetal material.

According to the above means, when the portion of the heater core wire facing the metal base is pressed against the metal base due to thermal expansion of the heater core wire during operation of the cathode ray tube, the heater support made of a bimetal material is thermally deformed. Since the distance between the portion of the heater core wire facing the metal base and the metal base is increased, the stress applied to the insulating layer of the heater core wire is greatly reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment of the present invention, a cathode structure of a cathode ray tube comprises a metal sleeve, a cap-shaped metal substrate fitted on one end of the metal sleeve, and having an electron-emitting material layer on the surface. A heater inserted and held in a metal sleeve,
In a cathode ray tube cathode assembly comprising an electrode support fixedly arranged on an electron gun and a heater support having a substantially U-shaped cross section coupled to an end of the heater, a plurality of heater supports having different thermal expansion coefficients are provided. When the temperature of the heater support increases during the operation of the cathode ray tube, the gap between the cap-shaped metal base and the heater opposed to the cap-shaped metal base is displaced in a direction in which the distance between the cap-shaped metal base and the heater facing the cap-shaped metal base increases. Metal materials and their bonded state are selected.

In one example of the embodiment of the present invention, the heater support has a bent portion which is bent outward from one end of a substantially U-shaped cross section along one longitudinal direction thereof, and one of the substantially U-shaped cross section. And a protrusion protruding from the outer side wall.

As a preferred example of the embodiment of the present invention, the heater support is made of a nickel-chromium-iron (stainless) alloy having a high thermal expansion coefficient as two metal materials having different thermal expansion coefficients. The one having a low coefficient of thermal expansion is made of a nickel-iron alloy (42% Ni, that is, amber).

According to the embodiment of the present invention, at the time of manufacturing the cathode assembly, the heater core wire is fixed to the heater support with relatively high precision under a normal temperature state in which the heater support is not deformed at all. In the completed cathode ray tube, when the heater core is energized, the portion of the heater core facing the metal base is pressed against the metal base due to the thermal expansion of the heater core, and the heater core is heated. When stress is applied to the insulating layer of the above, the distance between the portion of the heater core wire facing the metal substrate and the metal substrate is reduced due to the thermal deformation of the heater support formed by laminating a plurality of metal materials having different thermal expansion coefficients. As a result, the stress applied to the insulating layer of the heater core wire is greatly reduced.

Further, according to the embodiment of the present invention, the expansion of the interval between the portion of the heater core wire facing the metal base and the metal base due to the thermal deformation of the heater support should be constant without variation. Not only is not large enough to lower the heating temperature of the electron emitting material layer,
There is no adverse effect on the electron emission characteristics of the electron emission material layer.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of an embodiment of a cathode ray tube having a cathode structure according to the present invention, and shows an example in which the cathode ray tube constitutes a color picture tube.

In FIG. 1, 1 is a panel portion, 2 is a neck portion, 3 is a funnel portion, 4 is a fluorescent film, 5 is a shadow mask, 6 is an internal magnetic shield, 7 is a deflection yoke, and 8 is a magnet for adjusting purity. , 9 is a center beam static convergence adjustment magnet, 10 is a side beam static convergence adjustment magnet, 1
1 is an electron gun and 12 is an electron beam.

A tube (glass bulb) constituting the color cathode ray tube is disposed on the front side, and a panel portion 1 having a fluorescent film 4 formed on the inner surface of the front panel and a rear portion side are provided. It comprises an elongated neck portion 2 for accommodating the gun 11, and a substantially funnel-shaped funnel portion 3 connecting the panel portion 1 and the neck portion 2. The shadow mask 5 is fixedly arranged inside the panel section 1 and is held in a state facing the fluorescent film 4. The substantially trapezoidal internal magnetic shield 6 is disposed inside the tube at the connection portion between the panel unit 1 and the funnel unit 3. The deflection yoke 7 is attached to the outside of the tube at the connection portion between the funnel 3 and the neck 2.
Purity adjustment magnet 8, Center beam static convergence adjustment magnet 9, Side beam static convergence adjustment magnet 10
Are arranged side by side on the outside of the neck portion 2 and three electron beams 12 (1 in FIG. 1) radiated from the electron gun 11.
(Only the book is shown) is deflected in a predetermined direction by the magnetic field generated by the deflection yoke 7 and then passed through many electron beam transmission holes (not shown) provided in the shadow mask 5 to correspond to the fluorescent film 4. Is configured to reach the pixel of the desired color.

The operation of the color picture tube having the above structure, that is, the image display operation, is exactly the same as the image display operation of the known color picture tube. Therefore, the description of the image display operation of the color picture tube is omitted. I do.

FIG. 2 is a cross-sectional view showing an example of the configuration of the indirectly heated cathode structure of the color picture tube shown in FIG. 1, that is, the structure of the cathode structure according to the present invention. (B) shows a state when the heater support is not thermally deformed, and (b) shows a state when the heater support is thermally deformed.

2A and 2B, reference numeral 13 denotes a cylindrical metal sleeve made of a high melting point metal such as molybdenum;
14 is a cap-shaped metal base made of the same high melting point metal, 15 is an electron emitting material layer, 16 is a heater core wire, 17 is an insulating layer such as alumina, 18 is a dark coat coating layer such as tungsten fine powder, and 19 is a pair of cross sections. Substantially U-shaped heater support, 2
Reference numeral 0 denotes a metal sleeve holder for holding the metal sleeve 13, and reference numeral 21 denotes an electrode support fixed to the electron gun 11.

The cylindrical metal sleeve 13 has a cap-shaped metal base 14 fitted at one end, and the other end held by a metal sleeve receiver 20. Cap-shaped metal base 14
Has an electron emitting material layer 15 on the surface. The heater core wire 16 has an insulating layer 17 on the surface, and a dark coat coating layer 18 for improving heat radiation efficiency on the surface, and a central portion is inserted into the metal sleeve 13. The pair of heater supports 19 are made of a plate-shaped metal having a low coefficient of thermal expansion, for example, an iron-nickel alloy (42% nickel-iron alloy, that is, invar) 19a and a plate-shaped metal having a high coefficient of thermal expansion, for example, nickel A chromium / iron alloy (stainless steel) 19b is laminated in the thickness direction, and has a substantially U-shaped cross section. The pair of heater supports 19 has one side of a substantially U-shaped section welded to the electrode support 21 and the corresponding end of the heater core wire 16 is welded to the other side of the substantially U-shaped cross section. I have. The metal sleeve receiver 20 is fixed to the electron gun 11 by a holding member (not shown). As described above, the cathode assembly of the present embodiment has the same configuration as the known cathode assembly shown in FIG. 4 except for the configuration of the pair of heater supports 19.

The cathode structure of the present embodiment having the above-described structure operates as follows.

First, when power is not supplied to the color picture tube and the color picture tube is in a non-operating state, that is, when power is not supplied to the heater core wire 16 through the pair of heater supports 19, the cathode structure The temperature is near normal temperature, and the heater core wire 16 and the pair of heater supports 19 are also near normal temperature. In this state, FIG.
As shown in (a), since the heater core wire 16 does not thermally expand and the heater support 19 does not thermally deform, the pair of heater supports 19 have a substantially U-shaped cross section, and Although the interval S between the heater core wire 14 and the heater core wire 16 facing the metal base 14 is almost zero, the heater core wire 16 is not pressed against the metal base body 14 side, so the insulating layer covering the heater core wire 16 is not pressed. 17 is not stressed.

Next, when power is supplied to the color picture tube and the color picture tube enters an operation state, power is supplied to the heater core wire 16 through the pair of heater supports 19, and the metal sleeve 13 and the metal The temperature of the base 14 and the like becomes a high temperature state close to a predetermined heating temperature, and accordingly, the heater core wire 16 and the pair of heater supports 19 also become the same high temperature state. In this state, as shown in FIG. 2B, the heater core 16 thermally expands, so that the heater core 16 facing the metal base 14 is pressed against the metal base 14 to cover the heater core 16. Stress is applied to the insulating layer 17, but at the same time, the heater support 19 undergoes thermal deformation, and the heater support 19 changes from a substantially U-shaped cross section to a substantially U-shaped cross section with a slightly narrower opening. Then, the entire heater core 16 slightly moves in a direction away from the metal base 14, and the space S between the metal base 14 and the heater core 16 facing the metal base 14 is increased. In this case, the size and thickness of the plate metal 19a having a low coefficient of thermal expansion and the plate metal 19b having a high coefficient of thermal expansion are selected so that the distance S is about 50 μm at the maximum. Even in the state where the electron emission material layer 15 is spread by a maximum of about 50 μm, the heating temperature of the electron emission material layer 15 is not reduced, and the electron emission characteristics of the electron emission material layer 15 are not adversely affected.

When the color picture tube is changed from the operating state to the non-operating state, the heater support 19 does not thermally deform from the thermally deformed state as shown in FIG. Since the shape changes to a substantially U-shaped tube having a proper cross-sectional shape, the interval S between the metal base 14 and the heater core wire 16 facing the metal base 14 becomes substantially zero again.

As described above, according to the cathode assembly of the present embodiment, during operation of the color picture tube, the portion of the heater core 16 facing the metal base 14 is pressed against the metal base 14 due to the thermal expansion of the heater core 16. In this case, a heater support 19 made of a so-called bimetal material, in which a plate metal 19a having a low coefficient of thermal expansion and a plate metal 19b having a high coefficient of thermal expansion are bonded to each other, is thermally deformed. Opposing part and metal base 14
Since the space S between the heater core 16 and the heater core 16 is increased, the heater core 16 facing the metal base 14 is hardly pressed against the metal base 14, and stress is applied to the insulating layer 17 covering the heater core 16. It can be greatly reduced.

FIG. 3 is a perspective view showing another example of the configuration of the heater support 19 used in the cathode assembly of the present embodiment.

In FIG. 3, reference numeral 19c denotes a bent portion, 19d denotes a raised portion, and other components which are the same as those shown in FIG. 2 are denoted by the same reference numerals.

The bent portion 19c is bent outward at a substantially right angle from one edge of a substantially U-shaped cross section along the longitudinal direction of the heater support 19, and has a raised portion 19d.
Is slightly protruded from one outer wall having a substantially U-shaped cross section along the longitudinal direction of the heater support 19.

In this case, the reason why the bent portion 19c is provided is that the heater support 19 is provided in the manufacturing process of the cathode assembly.
When welding to the electrode support 21, the heater support 19
This is provided as a bending reinforcing member for preventing the occurrence of thermal deformation of the above, and the reason for providing the raised portion 19d is as follows.
In a color picture tube manufacturing process, a heater support 19 made of a bimetallic material is provided as a reinforcing member for preventing permanent deformation during heat treatment for degassing, for example, treatment in a hydrogen atmosphere at 1000 ° C. It is.

Also in the example of the configuration of the heater support 19, a plate-like metal having a low coefficient of thermal expansion, for example, an iron-nickel alloy (42% nickel-iron alloy, ie, amber material) 19a and a plate-like metal having a high coefficient of thermal expansion Metal, for example,
A structure in which a nickel-chromium-iron alloy (stainless steel) 19b is laminated in the thickness direction, that is, a bimetal material, similar to the heater support 19 used in FIGS. 2 (a) and 2 (b). The same operation and effect can be obtained.

In the above embodiment, the case where the cathode ray tube is a color picture tube has been described as an example. However, the cathode ray tube according to the present invention is not limited to a color picture tube, and other similar cathode ray tubes are used. The present invention can be similarly applied to a tube, for example, a monitor display picture tube.

In the above embodiment, the heater support 19 is made of an iron-nickel alloy (42% nickel-iron alloy, ie, Invar) as the plate-like metal 19a having a low coefficient of thermal expansion. Although the case where the plate-like metal 19b has nickel-chromium-iron alloy (stainless steel) has been described as an example, the constituent material of the heater support 19 in the present invention is not limited to the combination of the amber material and stainless steel. It is a matter of course that the bimetal material may be formed using another metal material similar to the amber material and stainless steel.

Further, in the above embodiment, the case where the heater support 19 has a two-layer structure of the plate-like metal 19a having a low thermal expansion coefficient and the plate-like metal 19b having a high thermal expansion coefficient has been described as an example. The heater support 19 in the present invention is not limited to a two-layer structure, but may have a three-layer structure or a four-layer structure.

[0042]

As described above, according to the present invention, when the cathode ray tube is operated, that is, when the heater core is energized,
A plurality of metal materials having different coefficients of thermal expansion when a portion of the heater core wire facing the metal base is pressed against the metal base side due to thermal expansion of the heater core wire and stress is applied to the insulating layer of the heater core wire. Due to the thermal deformation of the heater support formed by laminating the heater core, the distance between the portion of the heater core wire facing the metal base and the metal base is increased, so that the stress applied to the insulating layer of the heater core wire is greatly reduced,
There is an effect that separation of the insulating layer can be prevented.

Further, according to the present invention, the expansion of the distance between the metal base and the portion of the heater core wire facing the metal base due to the thermal deformation of the heater support can be maintained at a constant level without variation by appropriately configuring the heater support. Since the heating temperature of the electron emitting material layer is not so large as to lower the heating temperature of the electron emitting material layer, there is an effect that the electron emitting characteristics of the electron emitting material layer are not adversely affected at all.

Further, according to the present invention, the positioning of the heater core in the metal sleeve when the cathode assembly is manufactured may be determined at a position where the portion of the heater core facing the metal base contacts the metal base. There is also an effect that it can be performed simply, accurately and without using expensive members.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of a cathode ray tube having a cathode structure according to the present invention.

FIG. 2 is a cross-sectional view showing an example of the configuration of the indirectly heated cathode structure of the color picture tube shown in FIG. 1, that is, the cathode structure according to the present invention.

FIG. 3 is a perspective view showing another configuration example of the heater support in the cathode structure shown in FIG. 2;

FIG. 4 is a cross-sectional view illustrating an example of a configuration of a conventional cathode assembly.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Panel part 2 Neck part 3 Funnel part 4 Fluorescent film 5 Shadow mask 6 Internal magnetic shield 7 Deflection yoke 8 Magnet for purity adjustment 9 Magnet for center beam static convergence adjustment 10 Magnet for side beam static convergence adjustment 11 Electron gun 12 Electron beam DESCRIPTION OF SYMBOLS 13 Metal sleeve 14 Cap-shaped metal base 15 Electron emitting material layer 16 Heater core wire 17 Insulating layer 18 Dark coat covering layer 19 Heater support 19a Plate metal having a low coefficient of thermal expansion 19b Plate metal having a high coefficient of thermal expansion 19c Bent portion 19d Raised portion 20 sleeve receiver 21 electrode support

Claims (3)

[Claims] 1. A metal sleeve, a cap-shaped metal base fitted to one end of the metal sleeve, and having a surface coated with an electron emitting material layer, a heater inserted and held in the metal sleeve, and an electron gun. In a cathode structure of a cathode ray tube comprising a fixedly arranged electrode support and a heater support having a substantially U-shaped cross section respectively coupled to an end of the heater, a plurality of metals having different thermal expansion coefficients are used as the heater support. When the temperature of the heater support increases during the operation of the cathode ray tube, the gap is displaced in a direction in which the distance between the cap-shaped metal base and the heater facing the cap-shaped metal base increases. As described above, the cathode structure of the cathode ray tube, wherein the plurality of metal materials and the state of bonding are selected. 2. The heater support has a bent portion that is bent outward from one end edge of the substantially U-shaped cross section and one outer wall of the substantially U-shaped cross section along a longitudinal direction thereof. The cathode structure of a cathode ray tube according to claim 1, comprising at least one of the raised portions. 3. The heater support includes two metal materials having different thermal expansion coefficients, one having a high thermal expansion coefficient is a nickel-chromium-iron alloy, and the other having a low thermal expansion coefficient is a nickel-iron alloy. 3. The cathode structure of a cathode ray tube according to claim 1, wherein: