JPH01264131A - Cathode body structure - Google Patents

Abstract

PURPOSE:To nearly unify the operating temperature of three substrate metals and suppress the change of the color tone during operation by gradually increasing the heat quantity or heating efficiency of a thin film ribbon-shaped heating element deposited on a heat-resistant insulated substrate in zigzags toward both sides from the center section. CONSTITUTION:A thin film ribbon-shaped zigzag heating element made of tungsten is deposited and formed on a heat-resistant insulated substrate 1 to heater terminals on both sides. The heat quantity or heating efficiency of the heating element is gradually increased toward both sides from the center section, the heat quantity on both sides is increased, the temperature of a substrate metal at the center can be made nearly equal to the temperature of substrate metals at both sides. The temperature of three substrate metals is unified, the electron emission characteristic is stabilized over a long period, the change of the color tone during operation can be suppressed.

Description

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

[Conventional technology]

5 to 7 are enlarged plan views of a conventional cathode structure of this type. FIG. 5 is a plan view of the side where electron emission occurs, and FIG.
The figure is a plan view of the heating side, and FIG. 7 is a side sectional view. In each figure, l is a heat-resistant insulating substrate, for example 0.1 to 0.4
It is made of alumina or the like with a thickness around the threshold. 2a-2c
is a base metal arranged in a straight line, and the heat-resistant insulating group I
For example, nickel containing a trace amount of a reducing impurity element is deposited on one side of I by vacuum evaporation or sputtering. 4 is, for example, (Ba-3r-Ca)0
It is an electron emitting material made of an alkaline earth metal oxide such as, and is deposited on the three base metals 2a, 2b, and 2c by a method such as spraying. 3 is a lead wire, which is integrally formed on the insulating substrate 1 by the same method as the base metals 2a, 2b, and 2c. Reference numeral 3a denotes a cathode terminal at the tip of the lead wire, which is connected to the outside via a conductor wire (not shown). Reference numerals 5a, 5b, and 5c are heating elements, and tungsten or the like is formed in a meandering manner by spun multi-rings or the like at portions corresponding to the three base metals 2a to 2c on one side of the insulating substrate. 5d is a heating element 5a to 5c
This is a conducting wire that connects the two in series.

Reference numeral 6 denotes a heater terminal, which is not shown, but is connected to an external conductor 1% and a voltage is applied thereto.

Next, the operation will be explained. When a voltage is applied to the heater terminals 6 of the heating elements 5a to 5c, a current flows through the heating elements 5a to 5c, and Joule heat is generated by the product of the square of the current and the electrical resistance of the heating elements 5a to 5c, as shown in the formula below. occurs in an amount determined by

Q=I”XRxt...(1) However, Q
indicates the amount of heat, ■ indicates the current, R indicates the electrical resistance, and L indicates the time.

The above generated heat is transferred to the insulating substrate through thermal conduction and thermal radiation.
The three base metals 2a to 2c are heated through. When the base metals 2a to 2c are heated to an operating temperature of about a o o'c, an electron beam is emitted from the electron emitting material 4, causing the three-color fluorescent screen of the color cathode ray tube to glow.

In the cathode structure configured as described above, each heating element 5
By applying a voltage to a to 5C, each base metal 28 to 2c is
When setting the operating temperature to 00°C, the temperature of the central base metal 2b is the same as the base metal 2a on both sides.

The temperature is higher than that of 2c. The reason for this is that the heat generating elements 5a and 5c on both sides have heat conduction loss through the heater terminal 6, making it difficult for the temperature to rise, and the central heating element 5b is the same as the heating elements 5a on both sides.

This is because the temperature tends to rise due to heat radiation and conduction from 5c. Therefore, the temperature of the central base metal 2b located in the portion corresponding to the central heating element 5b is higher than that of the base metals 2a and 2c on both sides. Generally base metal 2a
The higher the temperature of ~2C is than the predetermined operating temperature, the faster the rate of diffusion and evaporation of magnesium and silicon, which are reducing elements contained in the base metals 2a to 2C and have the effect of activating the electron emitting material 4. This will accelerate the

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 2a on both sides.
Compared to that of 2c, it starts to deteriorate earlier, the balance of electron emission characteristics from the three base metals 2a to 2C is lost, and there is a drawback that a change in color tone on the phosphor screen, so-called white balance loss, occurs.

[Problem to be solved by the invention]

Since the conventional cathode structure is constructed as described above, the temperature of the central base metal 2b is higher than that of the base metals 2a and 2 on both sides.
As a result, the temperature of the central base metal 2
There was a problem in that the electron emission characteristics from b deteriorated early during operation, causing a change in color tone.

This invention was made to solve the above-mentioned problems, and the purpose is to obtain a cathode structure that can substantially equalize the operating temperatures of the three base metals and suppress changes in color tone during operation. shall be.

[i11! ! ! [Means for Solving the Problems] The cathode structure according to the present invention has a heating element in the form of a thin film ribbon attached to a heat-resistant insulating substrate in a meandering manner, so that the heat generation amount or heat generation efficiency is gradually increased from the center toward both sides. It is something that

[For production]

In this invention, the heat generation amount or heat generation efficiency of the heating element is gradually increased from the center to both sides, so the heat generation amount at both sides increases, and the temperature of the base metal in the center and the base metals on both sides increases. can be made almost the same.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a plan view of a cathode structure according to the present invention in which a heating element is adhered to a heat-resistant insulating substrate. is formed by adhesion. 6 is a heating element 5
These are the heater terminals on both sides. The heating element 5 has a thickness of 3 microns, a width of 0.2 M, and a pitch of 0.3 mm. Further, the heating element 5 is formed so that the length in the width direction of the heat-resistant insulating substrate l gradually increases from the center toward both sides. Note that the length of the central portion of the heating element 5 is 2.0 ws.

The extreme ends on both sides are 2.8-, that is, the electrical resistance value at the center of the heating element 5 is smaller than the electrical resistance value at both ends thereof. Therefore, as can be calculated from the above equation (1), the amount of heat generated at the center of the heating element 5 having a small electrical resistance value is smaller than the amount of heat generated at both ends. However, if this continues, the temperature at the center will be lower than the temperature at both ends, but it will rise due to heat radiation and conduction from both ends, and the temperature at the center and both ends of the heating element 5 will be almost equal. Become.

Fig. 2 shows another embodiment of the heating element 5, in which the ribbon width of the heating element 5 at the center is 0.3 mm, the ribbon width is gradually narrowed toward both sides, and the ribbon width at the extreme end is 0.3 mm. Set the ribbon width to 0.
It was set at 15 aus. As a result, the electrical resistance value at the central part of the heating element 5 becomes smaller than the electrical resistance value at both ends, and as in the above embodiment, the amount of heat generated at the central part of the heating element 5 is smaller than at both ends, but at both ends. The temperatures at the center and both ends of the heating element 5 become approximately equal due to heat radiation and conduction from the heating element 5.

FIG. 3 shows still another embodiment of the heating element 5, in which the heating element 5 has a film thickness of 3 microns and is made of a thin film of 0.2 square meters in width applied in a meandering manner. Further, the pitch P of the heating element 5 is set to 0.6- at the center of the insulating base Fi1, and the pitch is gradually narrowed from the center to both sides, and the pitch P at the extreme end is 0.6-.
was set to 0.4■. As a result, the smaller the pitch, the higher the heat generation efficiency and the easier the temperature will rise, and conversely, the larger the pitch, the less the heat generation efficiency will fall. In other words, the temperature of the heating element in the central part where the pitch is rough is difficult to rise, but the temperature of the central part of the heating element and both ends become almost equal due to heat radiation and heat conduction from both ends of the heating element 5.

As described above, by making the temperature of the heating element 5 substantially uniform over the entire area, the temperatures of the three base metals 2a to 2c facing the portion sandwiching the heat-resistant insulating substrate 1 can also be made uniform. is possible. FIG. 4 shows the temperature characteristics of the base metals 2a to 2c, and as shown by the O mark in the figure, the temperature difference between the center and both sides of the base metals has almost disappeared. Incidentally, regarding the temperature characteristics of the base metal of the conventional cathode structure, as shown by the X mark, the temperature of the center base metal 2b was about 30°C higher than the temperature of the base metals 2a and 2c on both sides.

In the embodiment, the material of the heating element may be a high melting point heat resistant metal such as molybdenum small titanium or rhenium other than tungsten.

〔Effect of the invention〕

As explained above, according to the present invention, the heat generation amount or heat generation efficiency of the heating element is gradually increased from the center to both sides, so that the temperature distribution of the heating element can be made uniform over the entire area. As a result, the temperature of the three base metals is also made uniform, the electron emission characteristics are stabilized over a long period of time, and changes in color tone during operation can be suppressed.

[Brief explanation of the drawing]

1 to 3 are respective plan views of the cathode assembly according to the embodiment of the present invention as seen from the heating element side, FIG. 4 is a graph showing the temperature characteristics of the cathode assembly, and FIGS. The front and back plan views of the cathode assembly and FIG. 7 are the same (cross-sectional views of the conventional cathode assembly). 1... Heat-resistant insulated substrate, 2a to 2C... Base metal,
53-5C...Heating element, 6...Heater terminal. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] Three base metals arranged in a straight line on one side of the heat-resistant insulating substrate, an electron emitting material coated on the base metal, and a thin ribbon-shaped thin film arranged in a serpentine shape on the other side of the insulating substrate. What is claimed is: 1. A cathode assembly comprising a heating element adhered to a substrate, wherein the heating element has a heat generation amount or heat generation efficiency that gradually increases from a central portion to both sides.