JPH01128331A - Cathode structure - Google Patents

Abstract

PURPOSE:To uniformize each temperature of plural pieces of heating elements by abating the heating value or heating efficiency of a heating element at the center lower than two heating elements at both sides. CONSTITUTION:Ribbon width of a heating element 5B at the center among three heating elements 5A-5C formed on a heat resistant insulating substrate 1 is being formed to be wider than each ribbon width of two heating elements 5A, 5C at both sides. In brief, an electric resistance value of the heating element 5B becomes smaller than that of these heating elements 5A, 5C. Consequently, heating value of the heating element 5B becomes smaller than that of the heating elements 5A, 5C. As leaving this state intact, temperature in the heating element 5A comes to be more lowered than that of the heating elements 5A, 5C, but it goes up by receiving heat radiation and heat conduction from both sides, and each temperature of the heating element 5B and the heating elements 5A, 5C comes to be almost equal. With this constitution, any variation in a color tone during operation of an in-line color picture tube is restrainable.

Description

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

[Conventional technology]

Figures 5 to 7 are enlarged views showing the conventional laminated cathode structure, Figure 5 is an enlarged plan view showing the side where electron emission is performed, and Figure 6 is the bottom view on the heating side. FIG. 7 is an enlarged side view.

In these figures 5 to 7, 1 is a heat-resistant insulating substrate made of, for example, alumina with a thickness of about 0.1 to 0.4 gourd, and 2a to 2c are heat-resistant insulating substrates. 9, which is a substrate metal arranged linearly on one side of the insulating substrate 1, that is, on the side where electron emission is performed, and this base metal 28~
2c is formed by depositing nickel containing a reducing impurity element by vacuum evaporation or sputtering.

On the base metals 2a to 2c, for example, (Ba.

Electron emitters 4 made of alkaline earth metal oxides such as Sr, Ca) θ are deposited by a method such as spraying.

Further, lead wires 3 are formed integrally with the base metals 2a to 2c on the heat-resistant insulating substrate 1 by the same method as the base metals 2a to 2c.

At the tips of these lead wires 3, there are terminals 3a to 3, respectively.
C is integrally formed. These terminals 3a to 3C are connected to the outside (not shown) by conductive wires.

On the other hand, the heating side of the heat-resistant insulating substrate 1 is shown in FIG.

As is clear from FIG. 7, the heating elements 5A to 5C are formed by sputtering or the like to adhere tungsten or the like in a meandering manner to the portions corresponding to the gold bases M2A to 2C, respectively.

These heating elements 58 to 5C are connected in series with a sub-heating element 5D. Both terminals of this series body are connected to a terminal 6, and the terminal 6 is connected to an external wire (not shown).

Next, the operation will be explained. Terminal 6 of heating elements 5A to 5C
When a voltage is applied to the heating elements 5A to 5C, a direct current flows through the heating elements 5A to 5C, and Joule heat is determined by the product of the square of the VC current and the electrical resistance of the heating elements 5A to 5C, as shown in the following equation (1). Occurs in

Q=I XRXt ・・・・・・・・・
(1) In this equation (1), Q is the amount of heat, (2) is the direct current, R is the electrical resistance, and t is the time.

This generated heat passes through the entire heat-resistant insulating substrate 1 and heats the three base metals 28 to 20 tons by thermal conduction and thermal radiation. When the base metals 2A to 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 fluorescent surface of the color cathode ray tube to glow.

In the conventional cathode structure configured as described above, voltage is applied to each of the heating elements 5A to 5C, and each of the base metals 2A
~2Ck When the operating temperature is about 800° C., the temperature of the central base metal 2B becomes higher than the temperature of the base metals 2A and 2C on both sides thereof.

The reason for this is that the heat generating elements 5A and 5C on both sides tend to lose heat conduction through the terminal 6, making it difficult for the temperature to rise.
This is because the temperature easily rises due to heat radiation and conduction from C.

Therefore, the temperature of the central base metal 2B located at a portion corresponding to the central heating element 5B is higher than that of the base metals 2A to 2C on both sides.

In general, the higher the temperature of the base metals 28 to 2C is than the predetermined operating temperature, the higher the reducing element that has the effect of activating the electron emitting substance 4 contained in trace amounts in the base metals 2A to 2C. It is interesting to accelerate the diffusion evaporation rate of magnesium and silicon.

As a result, when the operation is performed for a long time, the electron emission characteristics from the high-temperature central metal 2B begin to deteriorate earlier than those of the base metals 2A and 2C on both sides, and the three base metals 2A to 2C begin to deteriorate.
There was a drawback that the balance of electron emission characteristics from 2C was disrupted, resulting in a change in color tone on the fluorescent surface, so-called white balance disruption.

[Problem that the invention seeks to solve]

Since the conventional cathode structure is constructed as described above, the temperature of the central base metal is higher than the temperature of the base metals on both sides, and as a result, the electron emission characteristics from the central base metal are not stable during operation. There were problems in that it deteriorated early and caused a change in color tone.

This invention has been developed to solve the above-mentioned problems, and it is possible to make the operating temperatures of a plurality of base metals approximately the same and to suppress changes in color tone during operation as much as possible. The purpose is to obtain a cathode structure. .

[Means for solving problems]

The cathode assembly according to the present invention has a plurality of linearly arranged heating elements, in which the heat generation amount or heat generation efficiency of the central heating element is lower than that of the heating elements on both sides thereof.

[For production]

In this invention, by reducing the heat generation efficiency of the central heating element, the operating temperature of the central base metal can be made almost the same as the operating temperature of the base metals on both sides, and the color tone during operation can be changed. suppress changes in

〔Example〕

Embodiments of the cathode structure of the present invention will be described below with reference to the drawings. FIG. 1 shows one embodiment of the present invention, and is an enlarged bottom view of the side on which the heating element is attached to the heat-resistant insulating substrate.

In FIG. 1, the same parts as in FIG. 6 are given the same reference numerals, and detailed explanation thereof will be omitted. In the embodiment shown in FIG. 1, three heating elements 5A to 5 made of tungsten thin film are used.
The film thickness of 5C is 3 to 4 microns, and the size is 2 x 2 w.
It is the same as m, but the glue width of the central heating element 5B is 0.
2 seaweeds, heating elements 5A and 5C on both sides with 0 width
．． It is formed wider than 15-.

In other words, it is natural that the electrical resistance value of the central heating element 5B is smaller than the electrical resistance value of the heating elements 5A and 5C on both sides. Therefore, the amount of heat generated by the central heating element 5B, which has a small electric resistance value R, is smaller than that of the heating elements 5A and 5C on both sides.

If this continues, the temperature of the central heating element 5B will be lower than the temperature of the heating elements 5A and 5C on both sides, but,
By receiving heat radiation and heat conduction from both sides, the temperature increases, and the temperatures of the central heating element 5B and the heating elements 5A and 5C on both sides thereof become approximately equal.

FIG. 2 is a bottom view showing a second embodiment of the invention;
Three thin film ridge-shaped heating elements 5A made of tungsten
~5C is arranged in a meandering manner on the bottom side of the heat-resistant insulating substrate 1,
It is attached to a portion corresponding to the base metal.

The film thickness of these heating elements 5A to 5C is 3 microns, and the ribbon width is 0.2 microns. Among these heating elements 58 to 5C, the effective total length of the central heating element 5B! 15.8 mm, which is shorter than 25.8+w, which is the effective total length of the heating elements 5A and 5C on both sides.

That is, the electrical resistance value of the central heating element 5B is smaller than the electrical resistance values of the heating elements 5A and 5C on both sides thereof, and the amount of heat generated is also reduced.

FIG. 3 is a bottom view of a third embodiment of the invention. In this Figure 3, three thin films IJ made of tungsten,
The film thickness of the 3-inch heating elements 5A to 5C is 3 microns, and the rise width is 0.15! It is the same as I11, but the pitch P1 of the central heating element 5B, which is formed in a meandering shape, is set to four pitches, and the 0.3 pitch of the heating elements 5A and 5C on both sides P2 is also formed large. ing.

The three heating elements 5A to 5C are connected in series with the sub-heating element 5D as in the case of FIGS. 1 and 2. When a constant current flows and heat is generated, the smaller the pitch P is, the more If the pitch P is large, the heat generation efficiency is low and the temperature is difficult to rise.

That is, the temperature of the central heating element 5B with a coarse pitch becomes difficult to rise.

Next, a fourth embodiment of the invention will be described. When explaining this fourth embodiment, FIG. 6 shown in the conventional example will be referred to.

In this fourth embodiment, the width of the ribbon of the three heating elements 58 to 5C is 0.2 wm, but the thickness of the central heating element 5B is 3.5 microns, and the heating elements 5A on both sides are .

The total film thickness of 5C was 3 microns.

That is, the electrical resistance value of the central heating element 5B is smaller than the electrical resistance value of the heating elements 5A and 5B on both sides, and when the three heating elements 58 to 5C are connected in series and a constant current flows, the central heating element 5B The amount of heat generated by the heating element 5B decreases.

As described above, by making the temperatures of the three heating elements 58 to 5C almost uniform, the three base metals 2A, which are disposed facing the portions sandwiching the heat-resistant insulating substrate 1, are heated. It is also possible to equalize the temperature of ~2C.

Figure 4 shows the temperature characteristics of these base metals 2A to 2C.
As shown by the solid line X in this figure, it can be seen that the temperature difference between the center and both sides of the base metal has almost disappeared.

Incidentally, the temperature characteristics of the base metal of the conventional cathode structure are shown by the dotted line Y.
As shown, the temperature of the central base metal 2B was about 30° C. higher than the temperatures of the base metals 2A and 2C on both sides.

In addition, among the above embodiments, in the case of the third embodiment shown in FIG. 3, three heating elements 5A to 5Ct are connected in series,
Although shown in the example of heating with electricity, three heating elements 5A to 5Ci
A similar effect can be obtained when electrical heating is performed by connecting in parallel.

In addition, although tungsten was used as an example of the material for the heating element in all the examples, molybdenum was used as the material.

It may also be a high melting point heat resistant metal such as titanium or rhenium.

〔Effect of the invention〕

As described above, according to the present invention, the heat generation amount or heat generation efficiency of the central heating element is configured to be lower than that of the heating elements on both sides, so the temperature of the plurality of heating elements can be made uniform, and Result, '4. The temperature of several base metals is also made uniform, the electron emission characteristics are stabilized over a long period of time, and changes in color tone can be suppressed during operation.

[Brief explanation of the drawing]

FIG. 1 is an enlarged bottom view of the cathode assembly according to one embodiment of the present invention, showing the side on which the heating element is adhered, and FIGS. 2 and 3 are views of other embodiments of the cathode assembly of the present invention. FIG. 4 is an enlarged bottom view, and FIG. 4 is a graph showing the temperature characteristics of the cathode structure of the present invention. FIG. FIG. 6 is a bottom view of a conventional cathode assembly, and FIG. 7 is a sectional view of the conventional cathode assembly. ]... Heat-resistant insulating substrate, 2A to 2C... Base metal, 4... Electron emitting material, 5... Heating element. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (7)

[Claims] (1) Three base metals arranged linearly on one side of the heat-resistant insulating substrate, an electron emitting material coated on the base metal, and three base metals on the other side of the heat-resistant insulating substrate. In a cathode assembly comprising a plurality of heat generating elements formed in a meandering shape in the form of a thin film ribbon on a portion facing a base metal, the central heat generating element among the plurality of heat generating elements generates heat. A cathode assembly characterized in that the amount or efficiency of heat generation is reduced compared to the heating elements on both sides of the cathode assembly. (2) The cathode assembly according to claim 1, wherein the ribbon width of the central heating element is wider than the ribbon width of the heating elements on both sides thereof. (3) The cathode assembly according to claim 1, wherein the effective total length of the central heating element is shorter than the effective total length of the heating elements on both sides thereof. (4) Claim 1 characterized in that the pitch of the central heating element is wider than the pitch of the heating elements on both sides thereof.
The cathode structure described in Section 1. (5) The cathode assembly according to claim 1, wherein the thickness of the central heating element is greater than the thickness of the heating elements on both sides thereof. (6) Claims 1, 2, 3, and 4, characterized in that the plurality of heating elements are connected in series.
The cathode structure according to any one of Items 1 and 5. (7) Claims 1, 2, 3, and 4, characterized in that the plurality of heating elements are connected in parallel.
The cathode structure according to any one of Items 1 and 5.