JPH0364821A - Cathode body structure - Google Patents

Abstract

PURPOSE:To uniform the temperature of a substrate metal during its operation and restrain the variation of a color tone with temperature by forming a side edge-lead wires on the peripheral parts along the longitudinal direction on the back surface of a heat-resistant insulation substrate. CONSTITUTION:Snaking-like heating elements 5a-5c composed of three tungsten thin films are arranged in a straight line state on the back surface of a heat- resistant insulation substrate 1, and these heating elements 5a-5c are seriesly connected with a lead wire 5d. From the heating elements 5a and 5c in both sides, a ribbon-like side edge lead wire 7 extends to a 180 deg. opposite side along the peripheral part of the back surface of the heat-resistant insulation substrate 1 so as to be connected to a heater terminal 6. Since thus the side edge lead wire 7 is arranged on a peripheral part in a longitudinal direction on the back surface of the heat-resistant insulation substrate 1, heat loss produced via an outside lead wire can be relaxed, and also the emission from the peripheral part of the heat-resistant insulation substrate 1, of heat generated by a heating element 5 can be reduced. This enables the temperature of three substrate metals 2 to be uniformed, an electron emission characteristic to be stabilized, and thereby the variation of a color tone during an action to be restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cathode assembly. More specifically, the present invention relates to a laminated cathode structure used in an in-line color cathode ray tube.

[Conventional technology] Traditionally, in-line color cathode ray tubes have 5th to 7th
A laminated cathode structure as shown in the figure is used. Fifth
6 is an enlarged plan view of the electron emission side, FIG. 6 is an enlarged plan view of the heating side, and FIG. 7 is an enlarged sectional view of the cathode structure. 5th to 7th
In the figure, (1) is a heat-resistant insulated 8-board, for example 0
．． It is made of alumina or the like with a thickness of about 1 to 0.4 mm. (2a), (2b), and (2c) are base metals arranged in a straight line, and nickel or the like containing a small amount of reducing impurities is applied to the surface of the heat-resistant insulating substrate (1) by sputtering or the like. It is formed by adhesion method. (4) is an electron-emitting material made of an alkaline earth metal oxide such as (Ba, Sr, Ca) O, and is coated onto the metal substrates (2a), (2b), and (2C) by a method such as spraying. (3) is a lead wire, which is integrally formed on the heat-resistant insulating substrate (1) in the same manner as the base metal (2). (3a> is a lead wire) The cathode terminal at the tip of (3) is connected to the outside by a conductor (not shown). (5a), (5b)
, (5C) is a heating element, in which tungsten or the like is deposited in a serpentine shape by sputtering or the like on the back surface of the heat-resistant insulating substrate (1) corresponding to the base metals (2a), (2b), and (2C). has been done.

(5d) is three heating elements (5a>, (5b), (5C)
It is a conducting wire that connects in series the heating elements (5a), (5b),
(6) is a heater terminal connected to an external conductor (not shown), and a heating element (5C).
) is applied. (5e) is a conducting wire connecting the heater terminal (6) and the heating elements (5a) and (5C) on both sides.

In the cathode structure configured in this way, the heater terminal (
When voltage is applied to 6), the heating elements (5a), (5b), (
5c) Current flows through the equation (■): g, , 12xRxt (1) (in the equation, Q
is the amount of heat generated, i is the current, R is the resistance, and t is the time)
Joule heat expressed as is generated.

The generated Joule heat passes through the heat-resistant insulating substrate (1) to the three base metals (2a), (
2b), heat <2C>. Then, the base metal (2a
), (2b), and (2C) are heated to an operating temperature of about 800°C, an electron beam is emitted from the electron emitting material (4), causing the three-color phosphor screen of the color cathode ray tube to glow.

[Problem to be solved by the invention] However, as described above, each heating element (5a), (5b
>, (5c) to apply a voltage to the base metals (2a), (2
b) When bringing the operating temperature of (2C) to approximately 800°C, the temperature of the central base metal (2b) becomes higher than the temperature of the base metals (2a) and (2c) arranged on both sides thereof. .

The reason for this is that the heating elements (5a) and (5C) on both sides have a large heat conduction loss through the heater terminal (6), making it difficult for the temperature to rise.
The central base metal (2b) is arranged corresponding to the base metal (2b).
) is arranged on both sides of the base metal (2a),
The temperature becomes higher than that in (2c). Generally base metal (2)
The higher the temperature of
Sl and Mg, which are reducing elements that have the effect of activating
This will accelerate the rate of diffusion and evaporation.

As a result, when operating for a long time, the electron emission characteristics from the high-temperature central base metal (2b) change from the base metals on both sides (2b).
Compared to a) and (2C), it begins to deteriorate earlier, and the balance of electron emission characteristics from the three base metals (2) is lost.
There was a drawback that a change in color tone on the phosphor screen, so-called white balance collapse, occurred.

Furthermore, even within the same base metal (2), there is a temperature difference in the V direction shown in Figure 5. For example, there is a temperature difference of approximately 15°C between the centermost part and the most peripheral part of the base metal (2). . This has a cathode terminal (3) on the long side of the heat-resistant insulating board (1).
This is because heat conduction loss occurs through the external lead wires connected to this. Such a temperature difference also causes unevenness in electron emission characteristics within the same base metal (2).

The present invention has been made in view of the above-mentioned problems, and provides a cathode structure that can equalize the temperature of the three base metals (2) during operation and suppress changes in color tone even during long-time operation. The purpose is to

[Means for Solving the Problems] The cathode structure of the present invention includes three base metals arranged in a straight line on the surface of a rectangular heat-resistant insulating substrate, and an electron emitting base metal coated on the base metal. a substance, a heating element in the shape of a thin film ribbon meanderingly disposed at a position corresponding to each of the metal substrates on the back surface of the heat-resistant insulating substrate, a connecting wire connecting the heating elements in series, and the heat-resistant insulating material. It is characterized by comprising a side edge conductor wire disposed at the longitudinal periphery on the back surface of the substrate.

[Function] In the present invention, since the side edge conductor is disposed at the longitudinal peripheral edge on the back surface of the heat-resistant insulating substrate (1), it is possible to alleviate heat loss occurring through the external conductor, and also to reduce heat generation. body(
5) It is possible to reduce the release of the heat generated from the periphery of the heat-resistant insulating substrate.

[Examples] Hereinafter, examples of the present invention will be described based on the drawings, but the present invention is not limited only to these examples.

FIG. 1 is an enlarged view of the back side of the heat-resistant insulating substrate (1) of the cathode structure of the present invention. In FIG. 1, elements that are the same or similar to those of the conventional example are given the same reference numerals and their explanations will be omitted. As shown in Fig. 1, three meandering heating elements (5a), (5b), (5c) made of tungsten thin films are
These heating elements (5a>, (5b), and (5c) are arranged in a straight line on the back surface of the heat-resistant insulating substrate (1).
d> are connected in series. Heating elements on both sides (5a)
, (5c), a ribbon-shaped side edge conductor extends along the peripheral edge of the back surface of the heat-resistant insulating substrate (1) to the opposite side 180' and is connected to the heater terminal (6). These heating elements (5a), (5b>, (5c), conductor (5d)
), the side edge conductor (7), and the heater terminal (6) are all integrally formed of tungsten by sputtering. The thickness of these films is 3 mm and the width is 0.2 mm. This side edge conducting wire (7) may have a width of, for example, 0.14 mm, and may have a resistance value per unit length increased by 43% to serve as a sub-heating element. The film thickness, width, and resistance value per unit length for giving the side edge conductor (7) a function as a sub-heating element are not limited to the above, and the film thickness is 2 to 5 holes and the width is It can be appropriately selected in the range of 0.1 to 0.3 one, and the resistance value per unit length can be increased up to 50%. If the film thickness is less than 2 cylinders, the resistance value will vary,
On the other hand, if it exceeds 5 corals, the resistance becomes small and a problem arises in that it is difficult to generate heat. Furthermore, if the width is less than 0.1a, wire breakage may occur, resulting in reliability problems, while if it exceeds 0.3 mrs, miniaturization is impossible, and the resistance becomes small, causing problems in that heat generation is difficult.

Although not shown in the diagram, the heater terminal (6) has a diameter of 0.1
+m+s nickel wires are connected by welding, and heating elements (5a), (5b), (
A voltage is applied to heat 5c). When voltage is applied from the heater terminal (6), each heating element (5a), (5
In cases b) and (5c), Joule heat is generated as mentioned in the conventional example. In the conventional configuration, the heating elements (5a) and (5
c) and the heater terminal (6) is short.
), but with the configuration of the present invention, the heat conduction loss from the heating elements (5a) and (5c) to the heater terminal (6
), the temperature drop in the heating elements (5a>, (5c) due to thermal conduction loss can be ignored).

In addition, when the resistance of the side edge conductor ('7) is made larger than the resistance of the heating element (5) and used as a sub-heating element, the side edge conductor ('7)
) The temperature near the cathode terminal (3) increases easily.
It can also compensate for heat conduction losses through.

Figure 2 is a graph showing the temperature distribution of the base metals (2a>, (2b), and (2c)) when the side edge conductor (7) has a function as a sub-heating element. Therefore, the temperature distribution of the base metal in the conventional example is also described.As can be seen from Figure 2, in the embodiment of the present invention, the temperature distribution between the center base metal (2b) and the base metals (2a) and (2c) on both sides is It can be seen that there is almost no temperature difference.In contrast, in the conventional example, the temperature of the central base metal (2b) is lower than that of the base metals (2a) on both sides.
The temperature was about 30°C higher than that of , <2C).

Although it is not clearly shown in Fig. 2, the base metal (2
) The temperature difference, which was about 15°C between the middle 6th part and the outermost part, can be reduced to 5°C or less with this configuration, eliminating any practical problems.

FIG. 3 is an enlarged view of the back side of a heat-resistant insulating substrate (1) of another embodiment of the cathode structure of the present invention. In this embodiment, since the heater terminals (6) are arranged on both sides of the heat-resistant insulating substrate (1) at the approximate center, heat conduction from the heater terminals (6) of the heating elements (5a) and (5c) While reducing losses,
Heat conduction loss of the heating element (5b) can be reduced through the heater terminal (6) via the heat-resistant insulating substrate (1). Heat conduction loss through the heater terminal (6) of the heating element (5b) is compensated for by thermal radiation from the heating elements (5a), (5c) on both sides, and the heat loss is compensated for by the heat radiation from the heating elements (5a), (5c) on both sides.
(5c) The temperature can be made uniform.

Figure 4 shows the base metals (2a>, (2b), (2) of this example).
It is a graph which shows the temperature distribution of c). Similarly to FIG. 2, FIG. 4 also shows the temperature distribution of the base metal of the conventional example for comparison. As can be seen from FIG. 4, in this embodiment as well as in the previous embodiment, the temperature difference between the base metals (2a), (2b), and (2c) can be almost eliminated.

In the above description, tungsten was used as an example of the material of the heating element (5), but other heat-resistant materials with high melting points such as molybdenum, titanium, or rhenium may also be used. In addition, when the side edge conductor (7) is made to interact with the sub-heating element, the thickness of the side edge conductor (7) should be adjusted to match the thickness of the side edge conductor (7) between the heating elements (5a) and (5b).
, (5c) and the resistance value can be increased to exhibit this effect.

[Effects of the Invention] As explained above, according to the present invention, the temperature of the three base metals is made uniform, the electron emission characteristics are stabilized over a long period of time, and changes in color tone during operation can be suppressed. At the same time, temperature unevenness within the base metal is also improved and electron emission characteristics can be stabilized.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a plan view of a cathode assembly according to an embodiment of the present invention, FIG. 2 is a graph showing the temperature distribution of the cathode assembly according to the embodiment shown in FIG. A plan view of a cathode structure according to another embodiment of the invention,
FIG. 4 is a graph showing the temperature distribution of the cathode assembly of the embodiment shown in FIG. 3, and FIGS. 5 to 7 are a plan view, a back view, and a sectional view of the conventional cathode assembly. (Main symbols in the drawing) (1): Heat-resistant insulating substrate (2) Bi-substrate metal (4): Electron emitting material (5a), (5b), (5c): Heating element (5d): Conductive wire (6) : Heater terminal (7): Side conductor wire charge

Claims (3)

[Claims] (1) Three base metals arranged linearly on the surface of a rectangular heat-resistant insulating substrate, an electron emitting material coated on the base metal, and the three base metals on the back surface of the heat-resistant insulating substrate. A thin film ribbon-shaped heating element is arranged in a meandering manner at a position corresponding to each metal substrate, a connecting conductor wire is arranged to connect the heating elements in series, and a heating element is arranged in a longitudinal direction on the back surface of the heat-resistant insulating substrate. A cathode structure comprising a side edge conducting wire. (2) The cathode assembly according to claim 1, wherein the resistance value per unit length of the side edge conductor is greater than the resistance value per unit length of the heating element. (3) The cathode assembly according to claim 1, wherein the end portion of the side edge conductor is provided approximately at the center of the heat-resistant insulating substrate.