JPH0364824A - Cathode body structure - Google Patents

Abstract

PURPOSE:To enable the quick appearance of a picture image by shortening time from the start of electrification to that of electron emission by forming a heat-resistant black film on a heat-resistant insulation substrate. CONSTITUTION:A heat-resistant black film 7 is adherently formed on a part except a surface where the heating element 5 of a heat-resistant insulation substrate 1 is formed. When voltage is applied from a heater terminal 6, each of heating elements 5a-5c generates heat by Joule heat, and when a substrate metal 2 reaches a high temperature of about 800 deg.C, electron emission is stably made. At this time, the temperature of the black film 7 too becomes a high temperature of about 800 deg.C, the more temperature becomes higher, the more heat radiation loss from the insulation substrate 1 increases, and large input power is required to maintain an action temperature of about 800 deg.C. As a result of the increase of input power for heating the heating element 5, the temperature rise rate of the insulation substrate 1 after switch-on is quickened. This causes electron emission to be quickened to enable the quick appearance of a picture image.

Description

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

[Prior art] Traditionally, in-line color cathode ray tubes have 9th to 1st
A laminated cathode structure as shown in FIG. 1 is used. FIG. 9 is an enlarged plan view of the electron emission side, FIG. 1O is an enlarged plan view of the heating side, and FIG. 11 is an enlarged sectional view of the cathode structure. In FIGS. 9 to 11, (1) is a heat-resistant insulating substrate made of, for example, sapphire or alumina with a thickness of about 0.1 to 0.3 μ+. (2a>, (2b), (
2C) is a base metal arranged linearly, and nickel or the like containing a trace amount of reducing impurities is deposited on the surface of the heat-resistant insulating substrate (1) by, for example, sputtering. For example, (4) is (Ba,
5rSCa) is an electron-emitting substance made of an alkaline earth metal oxide such as 0, and the base metal (2a), (2b>,
(2c) It is deposited on top 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 cathode terminal at the tip of the lead wire (3), which is connected to the outside via a conductor wire (not shown). (5a>, <5b>, (5c) are heating elements, and the base metals (2a>, (2b>) on the back side of the heat-resistant insulating substrate (1)
, (2c), tungsten or the like is deposited in a meandering manner by sputtering or the like. (5
d> is a conductor that connects three heating elements (5a), (5b), (5c) in series;
c) and is formed integrally with it. (6) is a heater terminal connected to an external conductor (not shown), and a voltage for heating the heating element (5) is applied.

(5e) is a heater terminal (6) and heating elements (5a) on both sides,
(5c).

In the cathode structure configured in this way, the heater terminal (
When voltage is applied to 6), the heating elements (5a), (5b), (
5c) A current flows through the equation (■): Q=i2XRXt (1) (where Q is the amount of heat generated, i is current, R is resistance, and t is time), Joule heat is generated.

The generated Joule heat is transferred to the three base metals (2a), (2a) through the heat-resistant insulating substrate (1) by thermal conduction and thermal radiation.
2b) and (2c) are heated. Then, the base metal (2a
When 〉, (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 8 to be solved by the invention] However, in the cathode structure configured in this way,
Heating elements (5a>, (5b), (5c) 1.: Apply voltage (energize) to heat the base metals (2a), (2b), (2c) to about 1.

Electron emission is performed at an operating temperature of It takes about 10 seconds for the electron emission to start, that is, for the image to appear, and there is a problem in that it takes a little too much time for the electron emission to start.

In addition, as mentioned above, each heating element (5a>, (5b), (5
c) by applying a voltage to the base metals (2a), (2b>, (
2c) at an operating temperature of approximately 800°C, the temperature of the central base metal (2b) becomes higher than the temperature of the base metals (2a>, (2c)) placed on both sides.The reason for this is , the heating elements (5a>, (5c) on both sides are connected to the heater terminals (6
), which makes it difficult for the temperature to rise due to large heat conduction losses. Therefore, the temperature of the central base metal (2b) disposed corresponding to the central heating element (5b) is the same as that of the base metals (2a) and (2c) disposed on both sides.
〉 temperature becomes higher than that of 〉. In general, the higher the temperature of the base metal (2) is than the predetermined operating temperature, the lower the amount of reducing element that is contained in the base metal (2) and has the effect of activating the electron emitting substance (4). This will accelerate the diffusion and evaporation rate of 91 and Mg. As a result, when operating for a long time, the electron emission characteristics from the high-temperature central base metal (2b,) begin to deteriorate earlier than those of the base metals (2a) and (2c) on both sides. There was also a drawback that the balance of the electron emission characteristics from the metal (2) was disrupted, resulting in a change in color tone on the phosphor screen, which was referred to as a so-called white balance disruption. Furthermore, even within the same base metal (2), there is a temperature difference in the V direction shown in Figure 4. For example, there is a temperature difference of about 15°C between the centermost part and the edge of the base metal (2). There is. This is because the cathode terminal (3) is located on the long side of the heat-resistant insulating substrate (1), and heat conduction loss occurs through the external lead wire connected to the cathode terminal (3). 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 problems, and it shortens the time from the start of energization to the start of electron emission, achieves early appearance of an image, and equalizes the temperature of the three base metals (2) during operation. The purpose of the present invention is to provide a cathode structure that is capable of suppressing changes in color tone even during long-time operation, and that also has uniform temperature within the base metal and stabilizes electron emission characteristics. .

Means for Solving Problem 132] The cathode structure of the present invention includes a heat-resistant insulating substrate, three base metals disposed on one surface of the heat-resistant insulating substrate, and the other side of the heat-resistant insulating substrate. A cathode structure comprising three heating elements disposed at positions corresponding to the three base metals in the plane and a conductive wire connecting the three heating elements in series, the cathode structure comprising: It is characterized by a heat-resistant black film formed on the surface.

[Function] In the present invention, a heat-resistant black film is formed on a heat-resistant insulating substrate so that thermal radiation on the heat-resistant insulating substrate can be adjusted appropriately, so that the thermal characteristics of the cathode structure can be adjusted. It can be improved.

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

Example 1 FIG. 1 is a schematic diagram of a heating element of a cathode assembly according to Example 1, and FIG. 2 is a schematic diagram of an electron emitting surface of the cathode assembly shown in FIG. 1. In the following description, components that are the same or similar to those of the conventional example are given the same reference numerals, and the description thereof will be omitted.

On one side of the heat-resistant insulating substrate (1) are three meandering heating elements (5a), (5b) made of tungsten thin films.
(5c), each heating element (5a), (5b), (5c
) are connected in series by conducting wires (5d) and (5e). These heating elements (5a>, (5b), (5c), conductor wires (
5d>, <5o>, and the heater terminal (6) are all integrally formed of tungsten by sputtering.

The thickness of these films is 3 microns, and the heating elements (5a), (5b)
, (5c) and conductor (5dL (5o) width is 0.2
It is M. The film thickness and width are not limited to these, and the film thickness can be appropriately selected in the range of 1 to 5 microns, and the width can be appropriately selected in the range of 0.1 to 0.3 microns. A nickel wire (not shown) with a diameter of 0.1+U is fixedly connected to the heater terminal (6) by welding, and a heating element (
A voltage is applied to heat 5a), (5b>, and (5C)).

(7) is a heat-resistant black film, which is formed on the heat-resistant insulating substrate (1) made of sapphire with a thickness of 0.2 am, except for the surface on which the heating element (5) is formed. has been done. This heat-resistant blackness 1I (7) is formed by depositing carbon (C) or the like to a thickness of 2 microns by sputtering, vacuum deposition, or other methods.

Figure 2 shows the electron emission side and shows the base metal (2).
A heat-resistant black film (7) with a thickness of 2 microns is formed on a part of the part except for the part where it is deposited.

When voltage is applied from the heater terminal (6) to the cathode structure configured in this way, each heating element (5a), (5b), (5
C) generates heat due to Joule heat, as mentioned in the conventional example. When the base metal (2) reaches a high temperature of approximately 800°C, electron emission becomes stable. At this time, the temperature of the heat-resistant insulating substrate (1) also increases to approximately 800°C, which is approximately the same as the temperature of the base metal (2). ℃, and naturally the temperature of the heat-resistant black film (7) formed on the heat-resistant insulating substrate (1) also reaches a high temperature of about 800℃.At this time,
The heat-resistant black film (7) has a high thermal emissivity, and therefore, the higher the temperature becomes, the more the heat radiation loss from the heat-resistant insulating substrate (1) increases.

As a result, maintaining an operating temperature of approximately 800° C. requires greater input power than conventional devices. This heating element (5)
As a result of the increase in input power for heating the heat-resistant insulating substrate (1), the rate of temperature rise of the heat-resistant insulating substrate (1) after switching on becomes faster, and as a result, electron emission becomes faster and an image can appear earlier.

FIG. 3 shows the electron emission characteristics from switch-on. Conventionally, the start time of electron emission was 10 seconds, but according to the present invention, it was significantly shortened to 5 seconds.

Furthermore, the stabilization time to steady state has been shortened, and the brightness of the screen has been improved to stabilize more quickly. These causes are due to an increase in input power due to radiation loss.Incidentally, the input power was conventionally 2.3W, but in the present invention it is 3.
It is 8W.

Although carbon is used as an example of the material for the heat-resistant black film, the present invention is not limited to this, and the same effect can be achieved by using heat-resistant fine powder such as tungsten or molybdenum.

Example 2 FIGS. 4 and 5 are schematic diagrams of a heating element surface and an electron emitting surface of a heat-resistant insulating substrate (1) of a cathode assembly according to Example 2, respectively. The configuration of Example 2 has a central heating element (5b
) and the base metal (2b), except that the heat-resistant black film was formed only in the vicinity of the base metal (2b).

When voltage is applied from the heater terminal (6) to the cathode structure configured in this way, each heating element (5a), (5b), (5
C> generates heat due to Joule heat, as mentioned in the conventional example. When the base metal (2) reaches a high temperature of about 800° C., electron emission becomes stable. At this time, the temperature of the heat-resistant insulating substrate (1) has reached a high temperature of approximately 800°C, which is almost the same as the temperature of the base metal (2), and as a matter of course, the temperature in the center of the heat-resistant insulating substrate (1) The temperature of the heat-resistant black coating ('7) formed on the tube also reaches a high temperature of about 800°C. This heat-resistant black film (7) has a high thermal emissivity, and therefore, the higher the temperature becomes, the more the heat radiation loss from this vicinity, that is, from the center of the heat-resistant insulating substrate (1) increases. As a result, the temperature at the center of the heat-resistant insulating substrate (1) decreases, making it possible to maintain uniform temperature distribution over the entire area of the heat-resistant insulating substrate (1).

Figure 6 shows the temperature characteristics of the base metals (2a>, (2b), and (2c)), and as shown by the O mark in the figure, the temperature difference between the base metals (2) in the center and on both sides has almost disappeared. ,
The temperature characteristics of the base metal (2) of the conventional cathode assembly are as shown by the x mark, where the temperature of the central base metal (2b) is approximately 30°C compared to the temperature of the base metals (2a) and (2C) on both sides. The temperature was moderately high.

Example 3 FIG. 7 is a longitudinal sectional view of a cathode assembly according to Example 3. The structure of Example 3 is that a heat-resistant black film is formed on a heat-resistant insulating substrate (1) and a gold substrate (ri4) (2a), (2b), (2c).
It is the same as in Example 1 except that it is formed between.

When a voltage is applied from the heater terminal (6) to the cathode structure configured in this way, each heating element (5
a) to (5C) generate heat due to Joule heat.

A part of the generated heat is absorbed by the heat-resistant black thin film (sword) by heat conduction and heat radiation through the heat-resistant insulating substrate (1).
This heat-resistant black thin film I (7), base metals (2a) to (2
c) and the electron emitting material layer (4) are heated and their temperature increases.

In the conventional cathode structure, a part of the radiant heat passing through the heat-resistant insulating substrate (1) is reflected at the base metal (2a) to (2c)-heat-resistant insulating substrate (1) interface, and the radiant heat passes through the heat-resistant insulating substrate (1).
> and the rise in temperature of the electron emitting material layer (4) was slow.

In the present invention, by forming the heat-resistant black thin film (7), the absorption rate of radiant heat is improved, and the base metals (2a) to (2c) are formed.
) and the electron emitting material layer (4) can be heated and heated quickly. By increasing the temperature rise rate of the electron emitting material in this way, it is possible to shorten the time until electron beam emission starts. Figure 8 shows the electron emitting material layer (
4) is a graph showing the temperature change. This figure shows the temperature increase characteristics when the temperature of the electron emitting material layer (4) becomes stable at 800° C., and as indicated by the mark Q, the temperature increase characteristics have improved. Incidentally, the temperature increase characteristics of the conventional example are indicated by an x mark, and the time it takes to reach 600° C. is 19 seconds in the conventional example, but it is 12 seconds in Example 3, indicating that the temperature increase characteristics are improved.

[Effects of the Invention] As described above, according to the present invention, it is possible to make the temperature distribution of the cathode assembly uniform, and it is also possible to shorten the time from the start of energization to the emission of electrons.

[Brief explanation of drawings]

Figures 1 and 2 are schematic diagrams of the heat generating surface and electron emission surface of Example 1, respectively. Figure 3 is a graph showing the rise characteristics of electron emission in Example 1. Figures 4 and 5 are respectively FIG. 6 is a graph showing the rise characteristics of electron emission in Example 2. FIG. 7 is a longitudinal cross-sectional view of the cathode structure of Example 3. The figure is a graph showing the temperature characteristics of the electron emitting material layer of Example 3, FIG. 9 and FIG.
FIG. 11 is a longitudinal cross-sectional view of the cathode structure shown in FIG. 10; (Main symbols in the drawings) (1): Heat-resistant insulating substrate (2), (2a), (2b), (2c): Base metal (4): Electron emitting material layer (■, (5a), (5b) , (5c): Heating element (71: Heat-resistant black film agent Masuo Oiwa 3rd mouth time (sec) Engraving of the drawing Engraving of the drawing and Φg captive P O8 Akane time (sec) 0) Writing (method) 20 Name of the invention Cathode structure 3, Relationship with the case of the person making the amendment Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation Representative Moriya Shiki 4, Agent Address: 2-2-3-5 Marunouchi, Chiyoda-ku, Tokyo; Date of amendment order: November 28, 1999 (dispatch mill); 6. Subject of amendment (1) In the “Brief explanation of drawings” column of the specification ( 2) Contents of the amendment to drawing 7 (1) Insert the following sentence on a new line after "There is" on page 14, line 15 of the specification. The hatching in Figures 1 and 5 indicates a heat-resistant black film. Amend as shown in Figures 4 and 5. 8. List of attached documents

Claims (4)

[Claims] (1) A heat-resistant insulated substrate, three base metals disposed on one surface of the heat-resistant insulated substrate, and portions corresponding to the three base metals on the other surface of the heat-resistant insulated substrate. A cathode assembly consisting of three heating elements disposed on the substrate and a conductive wire connecting the three heating elements in series, wherein a heat-resistant black film is formed on the heat-resistant insulating substrate. Characteristic cathode structure. (2) The heat-resistant black film is applied to a portion of the surface on which the base metal is disposed where the base metal and the lead wire are not disposed, and a portion of the surface where the heat generating element is disposed where the heat generating element and the conductor wire are disposed. Claim 1: The invention is formed in a part where the invention is not provided.
The cathode structure described. (3) The cathode structure according to claim 1, wherein the heat-resistant black film is formed near the base metal at the center and near the heating element at the center. (4) The cathode assembly according to claim 1, wherein the heat-resistant black film is formed between the base metal and the heat-resistant insulating substrate.