JPH11162373A - Electron gun - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron gun, which can restrict the heating of a grid electrode part by heat conduction from a cathode. SOLUTION: A cathode support board 300 is arranged in rear of a first grid 200A of a grid electrode part. Cathodes 100a, 100B, 100C are inserted into the cathode support board 300 for fixation, and arranged opposite to each grid hole of the first grid 200A. A surface of the cathode support board 300 opposite to the first grid 200A and a peripheral surface thereof are formed with heat radiating function parts 300A, 300B. Each heat radiating function part 300A, 300B is coated with the printing paste of SiC as a black high heat conductive insulating material by screen printing. Heat from a cathode is radiated from each heat radiating function part 300A, 300B, and heat conduction to the first grid 200A is restricted so as to restrict the heating of the grid electrode part 200.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to various cathode ray tubes (C
In particular, the present invention relates to an electron gun provided with a means for suppressing heat transfer from the cathode side to the grid electrode unit side for controlling the electron beam.

[0002]

2. Description of the Related Art Conventionally, a cathode which is provided in a neck portion of a cathode ray tube and emits thermoelectrons, and a phosphor screen provided on an inner surface of a front panel of the cathode ray tube for accelerating and focusing the thermoelectrons emitted from the cathode. An electron gun having a grid electrode unit for supplying an electron beam to the electron gun is known. The cathode is
For example, a sleeve made of a heat-resistant metal is provided, and a thermoelectron emission member is arranged on the front end side of the heat-resistant sleeve, and a heater for heating the thermoelectron emission member is arranged on the rear end side.

[0003] Then, an impregnated cathode in which a heat-resistant porous material is impregnated with an electron-emitting substance to constitute a thermoelectron emission member, and an oxide-type cathode in which an oxide is used for the thermoelectron emission member, have become widespread. Further, the cathode is inserted and fixed to a cathode support substrate disposed close to and behind the first grid provided at the rearmost portion of the grid electrode portion, and is disposed so as to face a grid hole of the first grid. .

[0004]

By the way, in the above-mentioned conventional electron gun, the cathode side is heated to a high temperature to emit thermoelectrons, and this heat is transmitted to the grid electrode portion, and the heat is transmitted to the grid electrode portion. There is a problem that adversely affects the control of the electron beam by the laser beam. For example, when the first grid, which is particularly close to the cathode, is heated, barium Ba or the like evaporated from the cathode side adheres to the first grid, causing unnecessary electron emission from the first grid. As the temperature of the first grid is higher, the deposited barium Ba on the first grid is thermally activated, and electron emission occurs more frequently.

[0005] Then, there is a problem that a streaking phenomenon in which the screen shines brightly due to the unnecessary electron emission occurs. For example, in the case of an impregnated cathode, an operating temperature of 10
The temperature of the first grid rises to about 300 ° C. due to heat conduction from the cathode, and the brightness of the above-mentioned stray becomes about 2 mNi after 1000 hours of driving.
t (see FIG. 6).

SUMMARY OF THE INVENTION An object of the present invention is to provide an electron gun capable of suppressing heating of a grid electrode portion due to heat conduction on the cathode side.

[0007]

In order to achieve the above object, the present invention provides a cathode which is provided in a neck portion of a cathode ray tube and emits thermoelectrons, and accelerates and focuses thermoelectrons emitted from the cathode, A grid electrode unit for supplying an electron beam to a phosphor screen provided on the inner surface of the front panel of the cathode ray tube, wherein the cathode is disposed in the vicinity of a first grid provided behind the grid electrode unit; An insulating cathode support substrate provided in a state perpendicular to the optical axis of the first and second cathodes; and a cathode fixedly inserted into an insertion hole formed in the cathode support substrate and arranged so as to face a grid hole of the first grid. And a heat release function unit is provided on the outer peripheral surface of the cathode support substrate other than the surface facing the first grid.

In the electron gun of the present invention, the cathode is inserted into the insertion hole of the cathode support substrate, faces the grid hole of the grid electrode, and emits thermal electrons by heating by the heater. The thermoelectrons are accelerated and focused at the grid electrode unit, emitted forward, further deflected by a deflection magnetic field or the like, and supplied to the fluorescent screen provided in the front panel of the cathode ray tube.

The heat of the cathode, which has been raised to a high temperature by the heating of the heater, is transmitted to the cathode support substrate, and further transmitted to the first grid side of the grid electrode portion. A large amount of heat is dissipated by the heat-dissipating function unit provided on the outer peripheral end face facing the tube axis of the tube in the outer diameter direction. For this reason, the amount of heat transmitted to the first grid side is small, and the temperature rise of the first grid and each subsequent grid is suppressed. Thereby, the adhesion of the scattered barium Ba or the like to the grid electrode portion can be suppressed, unnecessary electron emission can be avoided, and the stray on the screen can be effectively prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electron gun according to the present invention will be described below. FIG. 1 is a partially broken side view showing a cathode support structure of an electron gun according to the present invention.
FIG. 2 is a plan view showing a cathode support substrate provided in the cathode support structure shown in FIG. FIG. 3 is similar to FIG.
FIG. 4 is a schematic side view showing an example of the overall configuration of the electron gun shown in FIG. 1, and FIG. 4 is a schematic sectional view showing an example of the configuration of a color cathode ray tube provided with the electron gun shown in FIG.

First, an outline of an electron gun and a cathode ray tube will be described with reference to FIGS. The color cathode ray tube shown in FIG. 4 is an example of a single electron gun 3 electron beam shadow mask type cathode ray tube. In this cathode ray tube, a front panel 20 is joined to a front portion of the funnel portion 10 by glass fusion or the like to evacuate the inside. On the inner surface of the front panel 20, a phosphor screen 22 made of a phosphor of three colors of RGB is provided. In the cathode ray tube, the fluorescent screen 22
Shadow masks 24 opposed to each other with a certain interval
Is arranged.

An electron gun 30 is provided on the neck 12 constituting the rear end of the funnel 10. Three electron beams 32R emitted from the electron gun 30;
32G and 32B are connected to the fluorescent screen 2 via the shadow mask 24.
2, and a color image is displayed. Further, as shown in FIG. 3, the electron gun 30 has three cathodes 100A, 100B, and 100C. Details of each of the cathodes 100A, 100B, 100C will be described later.

Further, these cathodes 100A, 100A
B, 100C forward along the tube axis Z (the fluorescent screen 22).
Direction), and the cathodes 100A, 100B,
First and second grids 200A and 200B for accelerating three electron beams emitted from 100C, and third to sixth grids 200C, 200D, 200E and 200F constituting a lens system for focusing the three electron beams. Is provided. Each of the grids 200A to 200F of the grid electrode unit 200 is formed in a plate shape or a cylindrical shape having grid holes through which three electron beams pass. In this example, the shadow mask type cathode ray tube is shown, but the same can be applied to a trinitron type cathode ray tube provided with an aperture grill as a shadow mask.

Next, the cathode 100A, 1
Regarding a support structure for supporting 00B and 100C,
This will be described with reference to FIGS. In FIG. 1, each of the cathodes 100A, 100B, 100C is inserted and held on a cathode support substrate 300. Cathode support substrate 300
Is made of an insulating material such as a ceramic disk such as forsterite or steatite.

As shown in FIG. 1, the cathode support substrate 300 is provided in parallel with the first grid 200A formed in a plate shape, and is arranged along a direction orthogonal to the tube axis Z. . Four attachment pieces 21 for attaching the cathode support substrate 300 are attached to the first grid 200A.
0A to 210D are provided. Each mounting piece 210A
210D extend rearward of the first grid 200A along the tube axis Z.

As shown in FIG. 2, the cathode support substrate 300 has a rounded rectangular planar shape, and has three insertion holes into which the cathodes 100A, 100B, and 100C are inserted. 310A, 310B, 31
0C is formed. Each of the insertion holes 310A, 310B,
310C is formed in a circular shape corresponding to the outer peripheral shape of the sleeves 110A, 110B, 110C of the cathodes 100A, 100B, 100C.
0B, 100C sleeves 110A, 110B, 110
A cylindrical sleeve holder 312A, 312B, 312C made of a heat-resistant metal for welding C is provided. These sleeve holders 312A, 312B, 31
On the outer periphery of 2C, each of the insertion holes 310A, 310B, 310
C to form a cylindrical glass 314A, 3
14B and 314C are provided.

The four mounting pieces 21 provided on the first grid 200A are attached to the cathode support substrate 300.
0A, 210B, 210C, and 210D, four mounting holes 320A, 320B, 320C, and 320 for insertion.
D is provided. Each mounting hole 320A, 320B,
320C, 320D are mounting pieces 210A, 210B,
It is formed in a rectangular shape corresponding to 210C, 210D, and mounting pieces 210A, 210B, 210C, 210D
Rectangular glass 316A, 3
16B, 316C and 316D are provided.

The surface of the cathode support substrate 300 on the side opposite to the first grid 200A (the surface shown in FIG. 2) and the outer peripheral end surface (the surface shown in FIG. 1) facing the tube axis Z in the outer diameter direction are heat. It is formed as emission function units 300A and 300B.
The heat release function units 300A and 300B are configured by applying a black film on the outer surface of the cathode support substrate 300, for example. This black film is coated with a printing paste obtained by mixing SiC powder, which is a black high thermal conductive insulator, and a binder to a thickness of about 0.1 mm by screen printing.
Sintered in an oxidizing atmosphere of 00 ° C or more.

As described above, a high thermal conductivity can be obtained by using a black insulating material having a high thermal conductivity as a material for coating the cathode support substrate 300. That is, the black substance has a characteristic that heat radiation is frequently performed. In addition, a high heat conductive material also has a characteristic that heat radiation is frequently performed. Therefore, by using the two characteristics in combination, it is possible to configure an effective heat release function unit.

FIG. 5 is an enlarged sectional view showing the structure of the cathode 100A. Since the cathodes 100B and 100C also have the same configuration as the cathode 100A, the cathode 100A will be described here. The cathode 100A has a sleeve 110A made of the above-described heat-resistant metal, and a thermoelectron emission member 120 is arranged on the front end side (front panel 20 side) inside the sleeve 110A, and the thermoelectron emission member is arranged on the rear end side. A heater 130 for heating the member 120 is arranged.

The thermoelectron emitting member 120 is a member formed by impregnating an electron-emitting substance with a heat-resistant porous material (impregnated cathode) or a member using an oxide (oxide cathode). Then, thermal electrons are emitted by heating by the heater 130. Also, such a cathode 100A,
100B, 100C are sleeves 110A, 110B,
110C is the sleeve holder 312A, 312 described above.
B, 312C by laser welding or the like.
It should be noted that welding is performed at the points indicated by x in FIG.

In the above configuration, the mounting pieces 210A, 210B, 210C, 2
10D and a mounting hole 320A of the cathode support substrate 300,
320B, 320C and 320D are glassed in a reducing atmosphere at about 1000 ° C.
B and 100C are arranged at a fixed distance from the first grid 200A and fixed to the sleeve holders 312A, 312B and 312C by laser welding. Thereby, each cathode 10
0A, 100B, and 100C are fixed in a state facing the grid holes 220A, 220B, and 220C formed in the first grid 200A.

In the above-described electron gun, as shown by a dashed line α in FIG. 5, heat generated from the heater 130 is transferred to the sleeves 110A, 110B, 110C and the sleeve holder 312.
A, the cathode support substrate 30 via 312B and 312C
0, and the mounting pieces 210A, 210B, 21
It is transmitted to the first grid 200A side via OC and 210D. However, the heat transmitted to the cathode support substrate 300 is
As shown by the arrow β in FIG.
00B, a large amount of heat is dissipated, and the amount of transmission to the first grid 200A side is suppressed. Thereby, the first grid 200A
Is suppressed. Therefore, the first grid 200
Unnecessary electron emission can be suppressed by suppressing the thermal activity of barium Ba to which A is attached.

FIG. 6 shows such a first grid 200A.
FIG. 4 is an explanatory diagram showing a change over time in stray luminance due to suppression of heating in comparison with a conventional case. The broken line A in FIG.
The measured value when the cathode supporting substrate 300 coated with C is used is shown, and the broken line B shows the measured value when the conventional cathode supporting substrate is used. As shown in the drawing, when the conventional cathode support substrate is used, the stray luminance increases to about 2 mNit by driving for 1000 hours. However, when the cathode support substrate 300 of the present example is used, the stray luminance is 1000 mNit. It can be suppressed to about 1/10, that is, about 0.2 mNit by driving with time.

In the above example, the cathode support substrate 3
Although the heat release function units 300A and 300B of No. 00 are formed by coating with SiC, aluminum nitride AlN may be used as another example. Instead of the black high heat conductive insulating material, only the black insulating material or only the high heat conductive insulating material may be used. Examples of the high thermal conductive insulating material include diamond and Be0. Thermal conductivity of each substance (W · m ^-1
(K ^-1 ) is 270 for SiC, 70 for AlN, 900 to 2000 for diamond, and 260 for BeO. For reference, forsterite is 3, steatite is 3, Al ₂ O ₃ (92%) is 17, and Cu is 394.

The binder may be either organic or inorganic. Further, the heat release function units 300A and 300B
Instead of screen printing, coating may be provided, for example, by spraying. The cathode may be either an impregnated type or an oxide type. In addition, the first of the cathode support substrate 300
Although the heat release function units 300A and 300B are provided on both the surface opposite to the grid 200A and the outer peripheral end surface, they may be provided on only one of them.

[0027]

As described above, in the electron gun of the present invention, the outer peripheral surface other than the surface of the cathode supporting substrate which is disposed close to the first grid of the grid electrode portion and faces the first grid of the cathode supporting substrate which supports the cathode. Was provided with a heat release function section.
For this reason, heat generated from the heater of the cathode is efficiently released in the direction away from the first grid by the heat release function portion in the cathode support substrate, and the heat transfer to the first grid side is suppressed. The temperature rise on one grid side can be reduced, unnecessary electron emission from the grid electrode can be suppressed, and problems such as strays can be prevented.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view showing a cathode support structure of an electron gun according to the present invention.

FIG. 2 is a plan view showing a cathode support substrate provided in the cathode support structure shown in FIG.

FIG. 3 is a schematic side view showing an example of the entire configuration of the electron gun shown in FIG.

FIG. 4 is a schematic sectional view showing a configuration example of a color cathode ray tube provided with the electron gun shown in FIG.

FIG. 5 is an enlarged sectional view showing a structure of a cathode supported by the cathode support structure shown in FIG.

FIG. 6 is an explanatory diagram showing a stray prevention effect by the cathode support structure shown in FIG. 1 in comparison with a conventional case.

[Explanation of symbols]

10: funnel portion, 12: neck portion, 20: front panel, 22: fluorescent screen, 24: shadow mask,
30 ... Electron gun, 32R, 32G, 32B ... Electron beam, 100A, 100B, 100C ... Cathode, 20
0: grid electrode parts 200, 200A: first grid, 210A, 210B, 210C, 210D: mounting piece, 300: cathode support substrate, 300A, 300
B: heat release function section, 310A, 310B, 310C
... insertion holes, 320A, 320B, 320C, 320D ...
... Mounting holes.

Claims (9)

[Claims] 1. A cathode provided in a neck portion of a cathode ray tube for emitting thermoelectrons, and a thermoelectron emitted from the cathode is accelerated and focused to form an electron beam on a phosphor screen provided on an inner surface of a front panel of the cathode ray tube. And an insulated cathode that is disposed adjacent to and behind a first grid provided at a rear portion of the grid electrode portion and that is provided in a state orthogonal to an optical axis of the cathode. A support substrate, and a cathode that is fixedly inserted into an insertion hole formed in the cathode support substrate and that is arranged so as to face a grid hole of the first grid, the first grid of the cathode support substrate An electron gun, characterized in that a heat release function portion is provided on an outer peripheral surface other than a surface facing the above. 2. The heat release function part is provided with a black film on a surface of the cathode support substrate opposite to the first grid and / or an outer peripheral end surface facing the tube axis of the cathode ray tube in a radial direction. 2. The electron gun according to claim 1, wherein the electron gun is constituted by: 3. The heat-dissipating function unit applies a high-thermal-conductivity film to a surface of the cathode support substrate opposite to the first grid and / or an outer peripheral end surface facing a tube axis of a cathode ray tube in a radial direction. 2. The apparatus according to claim 1, wherein
The described electron gun. 4. The electron gun according to claim 1, wherein a mounting piece extends behind the first grid, and the cathode support substrate is provided on the mounting piece. 5. The cathode support substrate has three insertion holes, three cathodes corresponding to three colors of RGB are inserted and fixed in each of the insertion holes, and three electron beams are emitted by the grid electrode part. The electron gun according to claim 1, wherein the electron gun is controlled. 6. The electron gun according to claim 1, wherein the cathode is fixed to an insertion hole of the cathode support substrate by glass fusion. 7. The cathode has a heat-resistant sleeve inserted into an insertion hole of the cathode support substrate, and a thermoelectron emission member is arranged on a front end side in the heat-resistant sleeve, and a rear end is provided. 2. The electron gun according to claim 1, wherein a heater for heating the thermoelectron emitting member is arranged on the side of the electron gun. 8. The electron gun according to claim 1, wherein said cathode is an impregnated cathode in which an electron-emitting substance is impregnated into a heat-resistant porous material to constitute said thermoelectron-emitting member. 9. The electron gun according to claim 1, wherein the cathode is an oxide cathode using an oxide for the thermoelectron emission member.