JPH1069861A - Electron gun - Google Patents

Abstract

(57) [Problem] To provide an electron gun that suppresses a high temperature of a first grid and prevents generation of stray electrons. An electron gun, the first grid G ₁ and the cathode KR (KG provided on a support 4 having an insulating property,
KB), and spacers 5 and 6 which are directly attached to the second grid which positions the first grid G ₁ at a predetermined interval with respect to the second grid and opposes the first grid G 1.
₁ is such that the plate thickness T ₁ is within the plate thickness of the spacers 5 and 6 and at least 0.2 mm or more. According to the electron gun,
Heat capacity thickness T ₁ of the first grid G ₁ is being increased is increased, the cathode KR (KG, KB) and heat between the first grid G ₁ is emitted to the outside through the first grid G ₁ By doing so, the increase in temperature is suppressed, and the generation of stray electrons can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun mounted on a cathode ray tube of a television receiver or a terminal display device.

[0002]

2. Description of the Related Art Generally, an electron gun is constituted by a plurality of electrodes called a grid arranged in parallel, and an electron beam emitted from a cathode is sequentially passed through the plurality of electrodes so that the electron beam emits electrons. The flow is controlled. As the electron gun, for example, three cathode structures 101 shown in FIG.
A type to be attached to a grid has been filed by the present applicant (Japanese Patent Application No. 3-213118).

[0003] The cathode structure 101 is formed into an approximately rectangular parallelepiped shape by an insulator such as a ceramic and has a through-hole portion 10.
2a and a support 1 having flat portions 102b, 102c and 102d formed at both ends of the through-hole portion 102a.
02, the first grid G ₁ is a plate-like member having a thickness of 0.2mm which is fixedly supported by brazing to one of the planar portion 102b of the support 102, the other flat portion 102c of the support 102 The cathode holder 104 includes a cylindrical cathode holder 104 that is attached so as to cover the through hole 102a, and a cathode sleeve 105 that is fitted and held in the cathode holder 104.

[0004] The cathode structure 101, the first grid for G ₁ side is attached to the second grid, a pair of spacers 103 for adjusting the second grid distance between the first grid G ₁ during the mounting , 103 are configured attached by respective brazing the flat surface portion 102d, 102d provided on both sides of the first grid G ₁ on the support 102.

[0005] A heater 106 is provided inside the cathode sleeve 105. The cathode sleeve 105 is covered with a cap 107 at the distal end, which has a smaller diameter than the base end, and an oxide as a cathode material that generates electrons by heat from the heater 106 on the cap 107. By forming a film 108, a so-called oxide cathode is formed.

[0006] The cathode structure 101 configured as described above.
In the electron gun provided with the heater, when the temperature of the heater 106 is raised to about 800 ° C., the heat generated from the heater 106 is transmitted to the cathode sleeve 105 and the cap 107 by radiation. In an electron gun, this heat is
By transmitting to the oxide 108 formed on the film,
The oxide 108 emits electrons.

The electron gun including the cathode structure 101 using the oxide cathode having the operating temperature of 800 ° C. as described above has a small variation among the three cathodes at the time of the initial cut-off, and has a low cut-off during the long-term operation. The off change is as small as 1% or less, and the withstand voltage characteristics are also extremely good.

[0008] In the electron gun successively all of the electrodes such as the second grid to fifth grid and convergence electrode electrons emitted from the oxide 108 does not beam transmitting hole 109 and shown, formed on the first grid G ₁ By passing through, an accelerated and converged electron beam is generated. This electron beam is scanned by the deflection yoke and focuses on a phosphor screen in a cathode ray tube (not shown) to form an image.

[0009]

Incidentally, the above-mentioned electron gun has a first grid in the case where heat treatment is performed in the manufacturing process of the cathode ray tube, or when the operation of the cathode ray tube becomes stable after the operation of the cathode ray tube is started. to suppress the fluctuation of the cathode cutoff voltage echoes due to the deformation of the G _1, it has a each independent structure of the three cathode structure 101.
Then, the electron gun, the plane of the support 102 made of a low ceramics thermal conductivity as compared with, and the metal that these are the first grid G ₁ in the cathode structure 101 is thick 0.2mm relatively small heat capacity Since each cathode structure 101 is joined to the portion 102b by brazing,
Has a property that the internal temperature of the liquid crystal easily rises.

In addition, the above-mentioned electron gun has a cathode structure 10
When the cathode 1 is an impregnated cathode for high current density, the operating temperature of the impregnated cathode is 1000 ° C. or higher, so that the temperature inside each cathode structure 101 and the temperature of the first grid G ₁ are extremely low. Get higher.

[0011] However, this electron gun, the interior of each of the cathode structure 101 becomes a high temperature, by cathode and temperature between the first grid G ₁ is raised, the oxide 108 of the barium evaporation is promoted. The evaporated barium is attached to the first inner surface and a beam transmission hole 109 of the grid G _1. Further, the deposited barium reacts with an oxidizing gas present in a cathode ray tube (not shown) to become barium oxide (BaO). This phenomenon becomes equivalent to decomposed by applying a first oxide 108 to the grid G _1.

[0012] Then, the barium oxide, by the reducing agent traces contained in the first material in the metal of the grid G _1, becomes prone state of so-called stray electrons under the high temperature. The stray electrons are generated even in a cut-off state in which regular electrons from each cathode are suppressed, and when the amount of generated electrons increases, it becomes impossible to suppress the current. And the image quality is significantly degraded.

The present invention has been proposed in order to solve the above-mentioned problems, and an object of the present invention is to provide an electron gun which suppresses a high temperature of a first grid and prevents generation of stray electrons. I do.

[0014]

An electron gun according to the present invention comprises:
A first grid and a cathode provided on an insulating support; and a spacer directly attached to the second grid that positions the first grid at a predetermined distance from the second grid and opposes the second grid. The first grid has a thickness within the spacer thickness and at least 0.2 mm or more.

According to the electron gun, since the plate thickness of the first grid is increased and the heat capacity is increased, the heat between the cathode and the first grid is radiated to the outside through the first grid, thereby increasing the temperature of the first grid. The formation of stray electrons can be prevented.

[0016]

Embodiments of the present invention will be described in detail with reference to the drawings. This embodiment is an example of a so-called Trinitron (registered trademark) electron gun in which electron beams emitted from three cathodes KR, KG, and KB are converged by one main lens.

In the electron gun of this embodiment, as shown in FIG. 1, an electron gun electrode group comprising a plurality of grids G ₁ , G ₂ , G ₃ , G ₄ , and G ₅ is provided to face each other. The pair of bead glasses 1 and 2 are sequentially arranged and supported in a vertical line with a predetermined spacing. That is, this electron gun has a second grid G ₂ , a third grid G ₃ , a fourth grid G ₄ , between a pair of bead glasses 1 and 2 arranged in parallel.
Are arranged with a predetermined spacing in tandem in the order of the fifth grid G _5, in the fifth grid G _5, which is the final electrode of the electron gun electrodes and the convergence electrode 3 is attached at its distal end It is configured.

In this electron gun, a main lens (a so-called unipotential lens) is constituted by the third grid G _{3 to} which the anode voltage is applied, the fifth grid G ₅ and the fourth grid G ₄ to which the focus voltage is applied. You. Then, the electron gun comprises three cathodes KR provided in the first back side of the grid G _1, KG, electron beams emitted from the KB intersect at the center (the center of the fourth grid G ₄₎ of the main lens, which The light further diverges, enters between the convergence electrodes 3, and irradiates the fluorescent screen of a cathode ray tube (not shown).

The electron gun as shown in FIG. 2, the first grid G ₁ is three cathodes KR, KG, are provided independently to KB. These first grids G
₁ is a pair of spacers made of a metal plate thicker than the first grid G ₁ and fixed to an insulating support 4 made of ceramic or the like without being beaded to the bead glasses 1 and 2. Second grid G through 5, 6
₂ is directly welded. Then, the electron gun, they first grid G _1, the support 4, the spacer 5 and 6, a cathode KR, KG, to form a cathode structure 20 by members of the KB and the like.

Each of these cathode structures 20 has the same structure as each other, and as shown in FIGS. 3 and 4, a support 4 and a first grid G attached to one surface of the support 4. ₁ and a pair of spacers 5 and 6, a cathode holder 18 attached to the surface on the opposite side of the support 4, and cathodes KR, KG,
It consists of KB.

The support 4 is made of an insulating non-metallic material such as a ceramic, for example.
Insulation between the grid G ₁ is adapted to be secured. The support 4 has a substantially rectangular parallelepiped shape as a whole, and a large-diameter circular hole portion 14 is provided at the center thereof through the member. The support 4 is provided with a flat portion 4 on one end side of the circular hole portion 14.
a is formed. The support 4 has plane portions 4b and 4c formed at both ends of the plane portion 4a at the same height as the plane portion 4a.
And 4c are separated from each other by a groove 4d. The support 4, the first grid G ₁ to the flat portion 4a, the planar portion 4b, the spacer 5 and 6 to 4c are attached by brazing, respectively.

On the other hand, the support 4 has a flat portion 4e formed on the other end side of the circular hole portion 14, and cathodes KR, KG and KB, which will be described in detail later, are formed on the flat portion 4e.
4 is installed so as to close it.

The first grid G ₁ is, as shown in FIG.
The main surface is formed as a planar substantially rectangular plate-like member having substantially the same area as the planar portion 4 a of the support 4. The first grid G ₁ has a cathode K at a substantially central portion of its main surface.
It has a small-diameter beam transmitting hole 7 for transmitting an electron beam emitted from R, KG, and KB.

The first grid G ₁ has a cathode K
R, KG, is G ₁ leads 13 for taking KB electrically connected is provided. The G ₁ lead 13 is continuous from one side edge of the main surface of the first grid G ₁ , and is provided to extend to the cathodes KR, KG, and KB along the outer periphery of the support 4. I have.

In this electron gun, the first grid G ₁
The thickness T ₁ of the has become a 0.3mm. In addition, this first
As shown in FIGS. 3 to 5, the grid G ₁ is coined (printed) so that the thickness T ₂ of the peripheral portion of the beam transmitting hole 7 is 0.1 mm so that the control of the electron beam is suitable. The coining unit 8 is provided. As described above, the plate thickness T ₁ of the first grid G ₁ is reduced from the conventional 0.2 mm to 0.3 mm.
mm, in this electron gun,
The first thermal conductive grid G ₁ is the fact that 50% improvement.

The spacers 5 and 6 fixed on the flat portions 4b and 4c of the support 4 are provided with the first grid G ₁ and the second grid G ₁ .
Those having a role for regulating the spacing of the grid G _2, flat portion 4b, a rectangular having substantially the same planar shape as 4c, and is formed as a thick metal plate than the plate thickness of the first grid G ₁ I have. When the spacers 5 and 6 are fixed on the support 4, the first grid G ₁
Step H ₁ in a height direction with respect to is the thickness such that the predetermined spacing. Then, the spacer 5 and 6, by being fixed by welding to said second grid G _2, so as to the first grid G ₁ and the second grid G ₂ is arranged with a predetermined spacing It has become.

On each support 4 of the electron gun, cathodes KR, KG, and KB for emitting an electron beam are attached to the flat portion 4e. Each of these cathodes K
R, KG, and KB each have a heater 19 wired inside, a cylindrical cathode sleeve 15 having a base end side slightly larger in diameter than a tip end side, and a cap put on the tip end of the cathode sleeve 15. This heater 1
The oxide 17 as a cathode material which generates electrons by the heat from 9 is coated to form a so-called oxide cathode. In addition, as a component of the oxide 17, for example, barium, strontium calcium ternary carbonate, or the like is used.

The cathodes KR, KG, KB
Is the side where the first grid G ₁ is provided is fitted on the opposite side of the support cylindrical mounted so as to block the circular hole 14 in the flat portion 4e side of the 4 cathode holder 18, the cathode sleeve 15 Is fixed to the cathode holder 18 by laser welding or resistance welding to the outer peripheral surface on the base end side and the inner peripheral surface of the cathode holder 18.

In this embodiment, the cathodes KR, KG, and KB of the cathode assembly 20 are formed using the above-described oxide cathodes. However, a cathode using an impregnated cathode for high current density is used. May be adopted. Here, although not shown, the impregnated cathode refers to one in which, for example, a sintered body of tungsten impregnated with barium-calcium aluminate is attached to the tip side of the cathode sleeve.

That is, in the impregnated cathode, a sintered body of tungsten is impregnated with barium-calcium aluminate, stored in a high-melting point metal cup such as Mo, and fixed by welding. After being inserted into the tip side of the cathode sleeve and fixed by welding, it is manufactured by sputtering a metal such as Ir or Os to the cathode surface layer to several thousand angstroms. As a result, the impregnated cathode is a cathode that easily emits and has a long life.

Next, an outline of a manufacturing process of the electron gun will be described with reference to FIG. The electron gun of the present invention
It is manufactured through a first brazing step S1, a second brazing step S2, a cathode welding step S3, a cathode assembly welding step S4, a beading step S5, and a heater / connection wire welding step S6.

In the first brazing step S1, the first brazing step
The grid G ₁ , the spacers 5 and 6, and the support 4 are joined by brazing. As described above, the support 4 is formed of an insulator such as ceramic.
The planar portion 4a, and pre-metallization process is performed on 4b and 4c, for these surfaces are two spacers 5, 6 and the first grid G ₁ is set that is molded into a predetermined shape as described above Brazing is performed.

Subsequently, in a second brazing step S2, each cathode holder 18 is brazed to the circular hole 14 on the flat surface 4e side of the support 4. Further, in the subsequent cathode welding step S3, after the cathode sleeve 15 in which the cap 16 was coated the above oxide 17 is Hikanmuri is the combined distance of H ₂ and the first grid G ₁ and the oxide 17 to a predetermined size The cathode structure 20 is completed by welding with the cathode holder 18.

The distance H ₂ between the first grid G ₁ and the oxide 17 is adjusted by pushing the cathode sleeve 15 into the cathode holder 18 while measuring the distance H ₂ with a microscope. In the cathode welding step S3, the sleeve using the impregnated cathode for high current density may be attached without using the oxide cathode.

In the subsequent cathode assembly welding step S4, FIG.
The second combined center and first beam transmission hole 7 of the grid G ₁ of the beam transmission hole 10 of the grid G _2, and welded to each cathode structure 20 spacer 5 and 6 between the second grid G ₂ as shown in, Fixed. Then, the next beading step S
In 5, and the second grid G ₂ is attached structure, a third grid G _3, a fifth grid G ₅ are beading by bead glasses 1,2 with multi forum glass by maintaining a predetermined distance .

Further, the following heater / connection wire welding step S6
In, the heater 19 is wired inside the cathode sleeve 15 and the lead wire from each grid and the stem are welded to complete the electron gun.

In the electron gun completed through the above steps, the heater 19 in the cathodes KR, KG, and KB is heated to 800 ° C., and the heat generated from the heater 19 is radiated to generate the cathode sleeve 15 and the cathode sleeve 15. Cap 1
Transfer to 6. In the electron gun, the heat is transmitted to the oxide 17 formed on the cap 16, thereby releasing electrons from the oxide 17.

[0038] In the electron gun, the electrons are sequentially transmitted to all of the electrodes such as a beam transmission hole 7 and the second grid G ₂ to the fifth grid G ₅ and the convergence electrodes 3 formed on the first grid G ₁ As a result, an accelerated and converged electron beam is generated. The electron beam is pulled by the high voltage and focuses on a fluorescent screen in a cathode ray tube (not shown).

At this time, in this electron gun, since the plate thickness of the first grid G ₁ is 0.3 mm and has a sufficient heat capacity, the cap 16 and the first grid G inside the cathode structure 20 are formed. heat between G ₁ is first
Reservoir grid G _1, and the heat is moderately radiated to the outside from the first grid G _1. Therefore, in this electron gun,
Excessive heating of the cathode structure 20 interior and the first grid G ₁ is being prevented. Specifically, the temperature of the first grid G _1, which rose to a conventional 300 ° C. about is, in this electron gun is suppressed to about 260 ° C., the temperature rise suppression effect of about 40 ° C. was obtained.

In the electron gun, even when the above-mentioned impregnated cathode having an operating temperature of about 1000 ° C. is used, the temperature of the first grid G ₁ , which has been raised to about 420 ° C. until now, reaches about 380 ° C. during the operation. It was confirmed that the effect of suppressing the temperature rise of about 40 ° C. was obtained as in the case where the above-described oxide cathode was used.

In the electron gun, each of the cathodes KR,
KG, by raising the temperature between KB and the first grid G ₁ is being suppressed, the less barium evaporation from oxide 17, adhesion is prevented to the first grid G ₁ of the barium. Further, in this electron gun, the first heat radiating effect of the grid G _1, since the temperature rise of the first grid G ₁ itself is prevented, stray electrons hardly occur thereby.

[0042] Thus, in the electron gun, it is possible to provide good cathode ray tube without spot characteristics that cause a degradation in image quality due to stray electrons from the first grid G _1, in terms of stability and the withstand voltage in the cutoff state .

In this embodiment, the plate thickness T ₁ of the first grid G ₁ is set to 0.3 mm, but the present invention is not limited to this. Thickness T ₁ of the first grid G ₁ may be any 0.2mm or more, for example may be of about 0.4mm thickness. On the other hand, even when the thickness T ₁ of the first grid G ₁ is further increased, the coining portion 8 of the beam transmission hole 7 of the first grid G ₁ is one of the characteristics of the CRT. The configuration is not changed in relation to the cutoff voltage.

Next, a first modification of the grid G ₁ will be described with reference to FIGS. The electron gun of the present invention, for improving the thermal radiation characteristics of the first grid G _1,
7 to 9, the first width in G ₁ leads 13
It may be extended until the width W of the main surface of the grid G _1.

In a first modification of the first grid G ₁ shown in FIG. 7, the plate thickness T _{1 is set} to 0.2 mm which is the same as the conventional _one ,
Width W of the main surface portion width of the first grid G ₁ in G ₁ leads 13
It has been extended to. Note that, in the first grid G ₁ in the first modification, the plate thickness T ₁ is the same as that of the conventional grid.
Since it is 2 mm, the coining portion 8 at the peripheral edge of the beam transmission hole 7 is not required. Electron gun, the same effect as the effect in case of using the first grid G ₁ having such a structure in the cathode structure 20 was obtained.

The second modification of the first grid G ₁ shown in FIG. 8, the main surface width of the first grid G ₁ of the first grid G ₁ in G ₁ leads 13 shown in FIGS. 3 to 5 It is expanded to the width W. That is, in the second modified example, the plate thickness T ₁ is 0.3 mm, and the main surface thereof is provided with the coining portion 8 on the periphery of the beam transmitting hole 7 as shown in FIG.

The first grid G ₁ having such a configuration
It is compared to the first grid G ₁ of the embodiment or the first modification of the embodiment described above, better to increase the applied heat escape of heat radiation due to the increase of the increase in heat transfer surface area due to increased cross-sectional area I do. Therefore, the electron gun uses the first grid G ₁ of the second modified example for the cathode structure 20, and thereby the inside of the cathode structure 20 and the first grid G _1.
Excessive temperature rise is prevented.

The third modification of the first grid G ₁ shown in FIG. 9 is a first modification of the first grid G ₁ of the second modification shown in FIG.
It is obtained by forming the radiation promotion layer 21 on the surface facing the second grid G _{2 1.} That is, the first of the third modified example
The grid G ₁ has a plate thickness T ₁ of 0.3 mm, a coiling portion 8 provided on the periphery of the beam transmitting hole 7, and a radiation promoting layer 21 on a main surface facing the second grid G _2.
Is provided.

The radiation promoting layer 21 is formed of the first grid G ₁
A rough surface 22 formed on the surface of the main surface facing the second grid G _2, and an oxide film 23 formed on the rough surface 22.
It consists of Of these, the rough surface 22 increases the surface area of the main surface portion of the first grid G _1, has a function of promoting heat radiation. On the other hand, the oxide film 23 has a substantially black color and has a function of promoting heat radiation. Thus, the first grid G ₁ is this radiation promotion layer 21, further improvement in more thermal radiation properties compared to the first grid G ₁ in the second modified example described above can be achieved.

[0050] In this first third modification of the grid G _1, although to form the radiation promotion layer 21 on only the surface facing the second grid G ₂ in the first grid G _1, G ₁ The lead 13 may be formed widely. Further, the radiation promoting layer 21 may be constituted by any one of the rough surface 22 and the oxide film 23.

[0051]

As described above in detail, according to the electron gun of the present invention, when the plate thickness of the first grid is within the plate thickness of the spacer, the plate thickness is increased, and heat dissipation due to heat conduction is increased. As a result, the heat between the cathode and the first grid is radiated to the outside through the first grid, whereby the temperature thereof is suppressed, and the generation of stray electrons can be prevented.

[Brief description of the drawings]

FIG. 1 is a front view showing an entire electron gun to which the present invention is applied.

FIG. 2 is a side view showing a state where each cathode of the electron gun is attached to a second grid.

FIG. 3 is an external perspective view showing a configuration of each cathode structure in the electron gun.

FIG. 4 is a cross-sectional view showing a configuration of each cathode structure in the electron gun.

FIG. 5 is a partially enlarged sectional view showing a peripheral portion of a beam transmission hole of a first grid.

FIG. 6 is a view showing an outline of a manufacturing process of the electron gun.

FIG. 7 is an external perspective view showing a first modification of the first grid.

FIG. 8 is an external perspective view showing a second modification of the first grid.

FIG. 9 is an external perspective view showing a third modification of the first grid.

FIG. 10 is a cross-sectional view showing a configuration of each cathode assembly in a conventional electron gun.

[Explanation of symbols]

1,2 bead glass, 4 support, 4a, 4b, 4
c, 4e flat portion, 4d groove, G ₁ first grid, G ₂
2nd grid, 5, 6 spacer, 7 beam transmitting holes, 8 coining part, 10 beam transmitting holes, 13 G
₁ lead, 14 circular holes, 15 cathode sleeve, 1
6 caps, 17 oxides, KR, KG, KB
Cathode, 18 cathode holder, 19 heater, 2
0 cathode structure

Claims (2)

[Claims] A first grid and a cathode provided on an insulating support; and a first grid and a cathode provided at a predetermined distance from the second grid and opposed to the second grid. An electron gun, comprising: a spacer attached to the first grid, wherein a thickness of the first grid is within a thickness of the spacer and at least 0.2 mm or more. 2. The electron gun according to claim 1, wherein the first grid has a lead portion whose width is extended at least to a width of a main surface portion attached to the support.