JPH06260099A - Electron gun and its manufacture - Google Patents

Abstract

PURPOSE:To suppress the generation of stray at the peripheral edge sections of through holes and improve the image quality and withstand voltage performance by providing a Ba diffusing absorber around the inner walls of the through holes of grid electrodes which electron beams of an electrode medium pass through. CONSTITUTION:The first grid electrode G1 of an electron gun is made of the nearly plate-like electrode substrate GS of the first grid electrode G1 made of stainless steel or Fe-Ni alloy, for example, and three electron beam passing through holes TH corresponding to three primary colors red, blue, and green are bored in a line on the electrode substrate GS. A Ba diffusing absorber SA made of a material diffusing and absorbing the Ba evaporated and scattered from a cathode electrode and stuck to the first grid electrode G1, e.g. gold, silver, or platinum, is fixed around the inner walls of the through holes TH. The Ba diffusing absorber is provided around the inner walls of the through holes of the second grid electrode like the first grid electrode G1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cathode ray tube (CRT),
The present invention relates to an electron gun provided in a color picture tube (CPT), a color display tube (CDT), a projection cathode ray tube (PRT), etc., and a manufacturing method thereof, and in particular,
The present invention relates to a technology capable of suppressing unnecessary electron emission from the first grid electrode or the second grid electrode of an electron gun to improve image quality and withstand voltage performance.

[0002]

2. Description of the Related Art For example, a cathode ray tube used for displaying a color image (hereinafter referred to as a color cathode ray tube) is a panel portion (face plate) which is an image screen, a neck portion for accommodating an electron gun, and a panel portion and a neck portion connected to each other. A deflection device for scanning an electron beam emitted from an electron gun on a phosphor screen coated and formed on the inner surface of the panel is attached to the funnel portion.

The electron gun housed in the neck portion is provided with various electrodes such as a cathode electrode, a control electrode, a focusing electrode and an accelerating electrode, and an electron beam from the cathode electrode is modulated by a signal applied to the control electrode. A desired cross-sectional shape and energy are applied through the focusing electrode and the accelerating electrode so that the fluorescent surface is bombarded. The electron beam is deflected in the horizontal and vertical directions by the deflecting device provided in the funnel portion on the way from the electron gun to the phosphor screen, thereby forming an image on the phosphor screen. 59-215
640 publication).

[0004]

Barium (Ba) is used in so-called oxide / cathode electrodes and impregnated cathode electrodes as the cathode electrode (cathode) for extracting thermoelectrons of the cathode ray tube. This Ba component is
It is essential to take out thermoelectrons efficiently,
Also in an electron gun for a cathode ray tube, the first grid electrode (G1) and the second grid electrode (G2), which are arranged close to the cathode electrode, evaporate and scatter, and adhere to their surfaces. The work functions of the surfaces of the grid electrode and the second grid electrode are lowered. As a result, unnecessary electrons (so-called stray: floating electrons) are generated also from the first grid electrode or the second grid electrode, and especially the through holes of the first grid electrode or the second grid electrode through which the electron beam from the cathode electrode passes. The stray generated and emitted from the peripheral portion of the cathode reaches the fluorescent surface of the cathode ray tube and causes a defective image, and the withstand voltage performance also deteriorates.

As a countermeasure against this, as described on page 71 of "Metal Material for Electron Tube" (editor: Japan Institute of Metals, published by Maruzen Co., Ltd.), "Grid Emission in Oxide Cathode Vacuum Tube" In the above, gold, silver, and platinum are mentioned as metals that diffuse and absorb BaO and Ba. Moreover, as a method of using these metals, plating is mentioned. For example, when the first grid electrode or the second grid electrode is coated with gold by gold plating, stray can be suppressed in the initial stage, but Ba
As it is absorbed, it is saturated immediately, and even if the coating film is thickened by that amount, the coating is peeled off, resulting in a problem that the life is short. Further, although gold or the like can be coated by vapor deposition instead of plating, it is more labor-intensive than plating. Further, as described above, the stray generated from the peripheral portion of the through hole of the first grid electrode or the second grid electrode poses a problem, so that the entire surface of the first grid electrode or the second grid electrode is subject to plating or vapor deposition. In the coating method, since the above materials are expensive, it is uneconomical and resource saving is not desirable.

An object of the present invention is to allow the electron beams of the first grid electrode and the second grid electrode of the electron gun to pass by a method which is good in productivity, economical, contributes to resource saving, and has a long life. An object of the present invention is to provide an electron gun capable of suppressing stray generated from the peripheral portion of the through hole and a manufacturing method thereof.

[0007]

In order to solve the above-mentioned problems, the present invention provides an electron gun including a cathode electrode, a first grid electrode and a second grid electrode, wherein the first grid electrode, the first grid electrode and the second grid electrode are provided. Gold or silver that diffuses and absorbs barium which is evaporated and scattered from the cathode electrode and adheres to the first grid electrode or the second grid electrode around the inner wall of the through hole through which at least one electron beam of the two grid electrodes passes. , An electron gun provided with a material such as platinum.

Further, according to the present invention, the first penetration which is slightly larger than the inner diameter of the completed second penetration hole through which the electron beam passes is provided at a predetermined position of the electrode base body which becomes the first grid electrode or the second grid electrode. A first step of forming a hole, a second step of placing a material for diffusing and absorbing barium in the first through hole, and a third step of crimping the material around the inner wall of the first through hole. And a fourth step of forming the second through hole in the substantially central portion of the material, and a method for manufacturing an electron gun.

Further, in the first step, there is provided a method of manufacturing an electron gun, wherein the upper and lower parts of the first through hole are tapered.

[0010]

According to the present invention, gold is provided around the inner wall of the through hole through which the electron beams of the first grid electrode and the second grid electrode pass,
Since a material such as silver or platinum that diffuses and absorbs Ba is provided, even if Ba protruding from the cathode electrode adheres to the periphery of the inner wall of the through hole, the material provided there diffuses and absorbs Ba, and Since the work function does not decrease, it is possible to prevent the occurrence of stray from the peripheral portion of the through hole, which causes a defective image and lowers the withstand voltage performance. In addition, as described above, in the conventional method of coating the entire surface of the first grid electrode or the second grid electrode by plating or vapor deposition, the effect of diffusion and absorption of Ba is initially obtained, but it is saturated immediately. However, even if the coating film is thickened by that amount, the coating film is peeled off. Further, since the stray generated from the peripheral portion of the through hole causes the defective image, it is wasteful and uneconomical also for the purpose of suppressing the stray. In this respect, in the present invention, since the expensive material is locally pressure-bonded only around the inner wall of the through hole, it can be efficiently provided in a main portion with a thick film thickness, and the diffusion and absorption effect of Ba is large, Moreover, it has high productivity, is economical, contributes to resource saving, and has a long life.

Further, by providing the upper and lower portions of the first through hole with taper, the above-mentioned material can be firmly fixed in the through hole and the through hole which is a source of stray which causes a defective image can be formed. Since the area of the material is enlarged in the peripheral portion, the evaporated amount of Ba from the cathode electrode can be received in a wider range, and the generation of stray from the peripheral portion of the through hole can be efficiently suppressed.

[0012]

EXAMPLES A color cathode ray tube to which the present invention is applicable will be specifically described below with reference to examples.

FIG. 3 is a schematic configuration diagram of a color cathode ray tube to which the present invention is applicable, in which 1 is a panel, 2 is a funnel,
3 is a neck portion, 4 is a fluorescent screen (screen), 5 is a shadow mask, 6 is a magnetic shield, 7 is a deflection yoke, 8 is a purity adjusting magnet, 9 is a center beam static convergence adjusting magnet, and 10 is a side beam static convergence adjusting. A magnet, 11 is an electron gun, Bc is a center beam, and Bs is a side beam.

Convergence adjustment (static convergence) of such a color cathode ray tube is performed by first obtaining the convergence of the two side beams Bs and Bs, and then
The center beam Bc and the convergence point of the side beam Bs are concentrated.

On the outer surface of the panel 1, a thin film containing SnO ₂ , In ₂ O ₃ or the like for preventing reflection and electrification is formed in a single layer or a multi-layer if necessary. Although not shown, an inner conductive film made of graphite or the like is deposited on the inner surfaces of the funnels 2 and the neck 3, and the conductive film contains titanium dioxide or the like in addition to graphite for controlling the arc resistance and controls the resistance value. is doing. The conductive film electrically connects the high voltage terminal (not shown) to the electron gun 11.

FIG. 4 shows the electron gun 11 to which the present invention is applicable.
FIG. 4 is a cross-sectional view of the G3 and G4 electrodes forming the bipotential type main lens in the horizontal direction and the vertical direction. In the figure, 111 is the outer peripheral portion of the G3 electrode, 121 is the outer peripheral portion of the G4 electrode, and 13 is the cup electrode. Reference numeral 112 denotes an astigmatism correction electrode provided inside the outer peripheral portion 111 of the G3 electrode, and 122 denotes an astigmatism correction electrode provided inside the outer peripheral portion 121 of the G4 electrode. The electrode plate 112 has an aperture 114 through which the central beam passes.
Opening holes 113 and 113 'through which the outer beam passes, the hole 122 through which the central beam passes, and opening holes 123 and 123' through which the outer beam passes are arranged in a line in the electrode plate 122. In this electron gun, the holes 113, 113 ', 11
4,123,123'124 are elliptical, and G
The shape and size of the openings corresponding to each other on the 3 side and the G4 side are the same. Outer openings 113, 113 ', 123, 12
If the 3'and the central apertures 114 and 124 have the same shape and the same size, the lens focusing action in the horizontal direction of the main lens formed on the outer side becomes stronger. It should be larger than the inner diameter of the hole in the horizontal direction so that the focusing action in both the horizontal and vertical directions is equal.

FIG. 5 shows the electron gun shown in FIG.
The outer peripheral portions 111 and 121 have a horizontal diameter h = 20.0 mm, the vertical diameter v = 9.4 mm, the central holes 114 and 124 have a vertical diameter a ₁ = 8.4 mm, and the electrode plate 112 is retracted d _1. = 1.
5 mm, eccentric distance S = 6.6 mm, central aperture 1
The ratios of the focus distances in both the horizontal and vertical directions to the horizontal direction diameter b ₁ of 14 and 124 are obtained by computer simulation.

The term "horizontal or vertical focus distance" as used herein means that an electron beam emitted from one point on the central axis at a certain outgoing angle and passing through the horizontal or vertical symmetry axis of the central aperture is focused by the main lens. The distance until it crosses the central axis again is measured from the end surface of the G3 electrode on the G4 electrode side. The distance from the end face to the fluorescent screen is set to 340 mm, the emission points at which the emission angles match this value of 340 mm are obtained, and the electron beam is emitted from the intermediate points between these emission points at the same emission angle. . FIG. 5 shows the ratio of the focus distances in both the horizontal and vertical directions at this time. As can be seen from the figure, if the horizontal diameter b ₁ of the central aperture is ≈ 5.5 mm, the vertical and horizontal focus distances will match, and the focusing action in both directions will be equal, so astigmatism will be reduced. Can be removed.

The lens focusing action at this time is 1 mm.
It has the same strength as a cylindrical bi-potential lens with a diameter of 8 mm, which is abutted at an interval of.

When h = 20.0 mm and S = 6.6 mm, this is L = h−2 × S (L = the limit value of the diameter of the opening, h =
The value is larger than the limit value of 6.8 mm for the electrode opening portion, which is restricted by the horizontal diameter of the opening, S = eccentric distance of the opening portion.

FIG. 6 shows the electron gun shown in FIG.
The relationship between the value of the horizontal diameter b ₁ of 3 ', 123, 123' and the horizontal spot movement distance of the outer electron beam on the fluorescent screen is obtained by computer simulation. 7 kV was applied to the G3 electrode and 25 kV was applied to the G4 electrode, and the distance from the end of the G3 electrode on the G4 electrode side to the phosphor screen was 340 mm. Since the outer electron beam and the central electron are 6.6 mm apart in the horizontal direction, the spot movement distance required to obtain the STC is 6.6 mm, but the degree of freedom in color purity adjustment is actually In order to leave the gap, it is often designed to about 6.1 mm. To secure this movement distance,
The value of b ₁ is 5.8 mm.

FIG. 7 is a sectional view of a main part of another electron gun of the color cathode ray tube according to the present invention, showing a vertical section of the G3 electrode. Openings 41, 4 provided in the electrode 112
1'and 42 have a shape in which the end points of two arcs are connected by two parallel straight lines. Although the spot shape on the phosphor screen is worse than that of an elliptical opening, it has an advantage that it can be easily and accurately machined because the opening is composed of an arc and a straight line. Also in this electron gun, the horizontal diameter of the aperture is smaller than the vertical diameter.

FIG. 8 and FIG. 9 are cross-sectional views of a main part of still another electron gun, showing vertical cross sections of the G3 electrode and the G4 electrode, respectively. The central apertures 52,62 have a vertical axis of interest, but the outer apertures 51,51 ', 52,5.
2'has no vertical axis of interest. Outer openings 51, 5
Reference numerals 1 ', 52 and 52' are a combination of two ellipses having the same major axis but different minor axes, and the outer openings 51, 51 'of the G3 electrode are smaller than the minor axis of the ellipse combined to the outside. Has become. When the outer aperture of the G3 electrode is formed in such a shape, the force for concentrating toward the center of the electron beam becomes stronger than in the case where the aperture is one ellipse like 113 and 113 'in FIG. Even if the diameter in the direction is made smaller,
STC can be taken.

On the contrary, in the G4 electrode, 61, 61 'in FIG.
As described above, when the outer opening is formed by combining two ellipses whose minor axis of the inner ellipse is smaller than that of the outer ellipse,
The force to concentrate the electron beam toward the center becomes stronger.

As described above, if the outer openings are made asymmetric with respect to the vertical direction, the concentration force on the electron beam increases, and S
It becomes easy to take TC. Also, if your concentration is too strong,
If the hole of FIG. 8 is used on the G4 electrode side and the hole of FIG. 9 is used on the G3 electrode side, the concentration can be weakened.

According to the present invention, the cylindrical electrode having the maximum diameter which is possible when the main lenses corresponding to the three colors of red, green and blue are juxtaposed on the same horizontal plane while the outer shape of the electron gun is restricted is provided. Since the main lens having a weaker focusing action than that of the case where they are butted together can be configured, there is an effect that the focus characteristic of the color CRT can be remarkably improved.

Further, the G3 electrode and the G constituting the main lens
The STC can be obtained by appropriately selecting the amount of retreat of the electrode plate and the shape of the hole formed in the electrode plate without displacing the central axis of the outer hole formed in the four electrodes. At the time of assembly, jigs having the same diameter and the same axis can be used for the G3 electrode and the G4 electrode, and the assembling accuracy can be improved.

FIG. 10 is a partially cutaway perspective view of another electron gun. The plates 133, 143 are shown in FIG.
Similar to the electrode plate, it has elliptical holes 135 and 145, respectively, but the elliptical holes are cut in half for the side beams on both sides, and the portions in contact with the outer peripheral electrodes 131 and 141 at both left and right ends are removed. There is. The passage of the central beam is formed by the holes 135 and 14 formed in the electrode plates 133 and 143, respectively.
5, the side beam passages on both sides are partially surrounded by the end portions of the electrode plates 133 and 143, and the remaining portions are surrounded by the outer peripheral electrodes 131 and 141. With such a configuration, it is possible to maximize the diameter of the main lens for the side beam, and since the area of the electrode plate is small, it is easy to increase the flatness and the elliptical aperture that requires high accuracy. There is an advantage that processing is easy because there are few molded parts. d
₃ and d ₄ indicate the amount of retreat, and either the same or different value is adopted.

In the electron gun of FIG. 10, the shape of the aperture is an ellipse. However, if the diameter of the aperture in the vertical direction is larger than the diameter in the horizontal direction, astigmatism can be removed with other shapes.

Further, as shown in FIG. 11, the electrode plates 133,
Astigmatism can also be eliminated by a structure in which 143 is curved and the amount of retreat of the polar plate is continuously changed. At this time, the vertical diameters of the openings 135 and 145 do not necessarily have to be larger than the horizontal diameter. When the electrode plate 133 of the G3 electrode is convex toward the G4 electrode side as shown in the drawing, the horizontal focusing force can be strengthened, and conversely, when the electrode plate of the G4 electrode is convex toward the G3 electrode side, vertical focusing is possible. You can strengthen your strength.

Further, as shown in FIG.
It is also possible to correct the astigmatism by providing protrusions 137 and 147 around 5, 145 and adjusting the protrusion amount of the protrusions. In this case as well, the vertical diameter of the opening need not be larger than the horizontal diameter.

Both the electron guns shown in FIGS. 11 and 12 can correct astigmatism while leaving the aperture as a perfect circle. In this case, in the case of non-circular aperture in both the parts processing and the electrode assembly. It has the advantage of being easier than.

According to this electron gun, the halo generated in the inner direction of the side beam can be removed and the effective aperture diameter of the main lens of the electron gun can be sufficiently enlarged, so that the focus characteristic of the color picture tube is remarkably improved. There is an effect that can be done. Further, since the areas of the electrode plates of the main lens facing each other are small, it is easy to obtain flatness during processing, and further, there are the advantages that the molding is easy because there are relatively few processing points.

Of course, the electron gun of the present invention can be applied to the main lens of the above-mentioned bipotential type or other types. Further, in the above description, the example in which the present invention is applied to both of the pair of electrodes forming the main lens has been described, but the same effect can be obtained by applying the present invention to only one of the electrodes.

FIG. 13 shows a front view (a), a side view (b), a rear view (c) and a plan view (d) of another electron gun having first to sixth grids to which the present invention can be applied. . In the figure,
1111 (G1) is the first grid, 1112 (G2) is the second grid, 1113 is the third grid, 1114 is the fourth grid, 1115 is the fifth grid, 1116 is the sixth grid.
The grid 1119 is a cathode. This electron gun uses a plurality of main lenses to obtain good focus characteristics. To obtain a bright and high-resolution image, the anode voltage E
It is necessary to increase the value of b, usually Eb is 25 to 35 kV
Is. The focus voltage Ec ₃ is about 30% of Eb, and the applied voltage Ec ₂ of the second grid 1112 is 400 to 700V.
First grid 1111 is grounded, cathode 11
A signal voltage Ek of 200 V or less corresponding to the brightness of each picture element is applied to 19. Further, 1127 is a third grid power supply line, 1128 is a fifth grid power supply line, and one end 1127a of the third grid power supply line 1127 is fixed to the third grid 1113 as shown in FIGS. 13B and 13C. At the same time, a part of the intermediate portion 1127b is formed as a bent portion 1127c extending substantially parallel to the plane orthogonal to the tube axis.
127c is passed through the middle of the back surface of the bead glass 1120 and the inner wall surface of the neck tube (not shown) within the overall length 1 of the third grid 1113 in the tube axis direction, and the other end 1127d is connected to a stem lead (not shown). . This causes the same operation as the shield wire. Meanwhile, the third grid 1
As shown in FIGS. 13 (a) and 13 (b), the fifth grid feeder line 1128 connecting the 1113 and the fifth grid 1115 has one end 1128a at the third grid 1113 and the other end 1128d at the fifth grid 1115. And a part of the intermediate portion 1128 is formed as a bent portion 1128c extending substantially parallel to a plane orthogonal to the tube axis.
28c are symmetrically arranged within the entire length 1 of the third grid 1113 in the tube axis direction and on the same plane orthogonal to the tube axis with the bent portion 1127c sandwiching the tube axis, and the rear surface of the bead glass 120 and the neck tube are arranged. It passes through the middle of the wall surface (not shown) and has the same function as the shield wire. That is, since the feed lines 1127C and 1128C are symmetrically arranged on the same plane sandwiching the tube axis and orthogonal to the tube axis, as compared with the case where the shield wire is arranged only on one side,
It has an excellent feature that it exhibits the effect of suppressing arc discharge over the entire circumference of the neck tube.

By disposing the bent portions 1127c and 1128c symmetrically across the tube axis within the entire length of the third grid in the tube axis direction like the present electron gun, the number of arc discharges can be increased. Compared with the conventional one, it can be reduced to a fraction or less and the dark current value can be similarly reduced to a fraction or less. That is, in terms of shielding the bead glass and the wall of the neck tube from the anode voltage, it is better to provide the bent portion near the electrode to which the anode voltage is applied. It is also possible that arc discharge easily occurs. On the other hand, if the bent portion of the focus voltage applying power supply line is too close to the second grid electrode side, the focus voltage is a high voltage, which is as high as the anode voltage. Therefore, the bent portion of the focus voltage applying power supply line and the second grid electrode, etc. The risk of generating arc discharge with the low-voltage applying electrode becomes large.

Regarding the position of the bent portion of the focus voltage applying power supply line, the bent portion was examined based on various experiments, from the viewpoints of the effect of suppressing arc discharge generation, the effect of suppressing dark current, and the workability of electrode assembly. Is optimally provided at a position facing the side surface within the overall length 1 of the third grid in the tube axis direction.

According to this electron gun, since both ends of the power supply line are fixed to the electrodes and the like, there is no fear of becoming a source of stray electrons, and there are effects of preventing arc discharge and suppressing dark current.

FIG. 1A is a plan view of a first grid electrode of an electron gun according to an embodiment of the present invention, and FIG. 1B is a plan view thereof.
It is sectional drawing in the AA cutting line of (a).

G1 is a first grid electrode, GS is a substantially plate-like electrode base of the first grid electrode G1 made of, for example, stainless steel or Fe-Ni alloy, and TH is a phosphor of three primary colors of red, blue and green (see FIG. 14) through which three electron beams corresponding to the through holes are formed in the electrode substrate GS in a row, three through holes, SA are fixed around the inner wall of the through hole TH,
Evaporation from the cathode electrode (see reference numeral 1119 in FIG. 13),
It is a Ba diffusion absorber made of a material that diffuses and absorbs Ba (barium) that scatters and adheres to the first grid electrode G1, such as gold, silver, or platinum.

It should be noted that the second grid electrode G2 also has a structure shown in FIG.
Similar to the first grid electrode G1 shown in (a) and (b), Ba is provided around the inner wall of each through hole of the second grid electrode G2.
A diffusion absorber was provided.

Next, a method of providing the Ba diffusion absorber SA around the inner wall of the through hole TH of the first grid electrode G1 (or the second grid electrode G2) shown in FIG. 1 will be described with reference to FIG.

First, as shown in FIG. 2 (a), the first grid electrode G1 has an electrode base GS made of stainless steel or a Fe-Ni alloy, and tapered portions TP are provided on the upper and lower surfaces of the electrode base GS in advance. After that, the first through hole TH ′ having an inner diameter of about 1.1 to 1.5 times the inner diameter (for example, 0.6 to 0.7 mm) of the completed through hole is opened.

Next, as shown in FIG. 2B, after the electrode base GS is placed on the lower guide LG having the lower punch LP, a cylindrical shape is formed in the first through hole TH 'of the electrode base GS. Insert a gold, silver, or platinum Ba diffusion absorber SA.

Next, the cylindrical Ba diffusion absorber SA is pressed using the lower guide LG, the lower punch LP, the upper guide UG, and the upper punch UP, which are coaxially combined, and the thickness of the electrode substrate GS is almost the same. Crush to t. At this time, the cylindrical Ba diffusion absorber SA is the tapered portion TP of the electrode substrate GS.
So that the volume of the cylindrical Ba diffusion absorber SA is slightly smaller than the volume of the space of the first through hole TH ′ of the electrode base GS, the upper punch UP has a circular shape. The columnar Ba diffusion absorber SA is cut into the middle thereof. When the volume of the cylindrical Ba diffusion absorber SA is larger than the volume of the space of the through hole TH 'of the electrode substrate GS, although not shown here, the lower punch LP is adjusted by being depressed by that amount. can do.

Then, the upper punch UP is continuously pushed down, and as shown in FIG.
A second through hole TH is formed by penetrating substantially the central portion of the Ba diffusion absorber SA filled with the first through hole TH ′ having P.

Through the series of steps shown in FIGS. 2A to 2D, the Ba diffusion absorber SA is locally pressure-bonded (mechanically formed) only around the inner wall of each through hole TH of the first grid G1. And a tightly fitted structure is obtained.

The surplus portion SA 'from the columnar Ba diffusion absorber SA produced by the step of FIG. 2D is recovered because the material is an expensive material such as gold, silver or platinum. Further, in the above processing, gold is most preferable as the material of the Ba diffusion absorber SA because of its excellent malleability.

The required amount of the Ba diffusion absorber SA of the first grid electrode G1 obtained by the above steps is, for example, the first
In the case of an example in which the inner diameter of the through hole TH ′ is 1.25 times the inner diameter of the second through hole TH after completion, the thickness when uniformly plated on the entire surface corresponds to about 0.16 μm. Then
It turns out that it is an efficient use.

Moreover, the Ba diffusion absorber SA in the present embodiment can be firmly fixed to the electrode base GS even by the structure in which it is mechanically pressure-bonded around the inner wall of the through hole TH. Further, in order to obtain even stronger adhesive strength, after the step of FIG. 2D is completed, heat treatment is performed in a reducing atmosphere such as hydrogen, so that the interface between the electrode substrate GS and the Ba diffusion absorber SA is formed. It is firmly fixed with.

Further, the tapered portions TP provided above and below the through hole TH of the electrode substrate GS not only have the function of firmly fixing the Ba diffusion absorber SA in the through hole TH, but also
Since the area of the Ba diffusion absorber SA is enlarged in the peripheral portion of the through hole TH where a stray that causes a defective image is generated, it is possible to receive the evaporation amount of Ba from the cathode electrode in a wider range. It is possible to effectively prevent the occurrence of stray, which is a problem.

As described above, in this embodiment, the first
A Ba diffusion absorber SA of gold, silver, platinum or the like is mechanically formed and fitted around the inner wall of each through hole TH through which the electron beam of the grid electrode G1 and the second grid electrode G2 passes, by utilizing its malleability. Even if Ba evaporated and scattered from the cathode electrode adheres to the inner wall periphery of each through-hole TH, the Ba diffusion absorber SA provided there diffuses and absorbs Ba, and the work function of that portion is Since it does not lower, each through hole T
Generation of stray from the peripheral portion of H can be suppressed, image quality is improved, and withstand voltage performance is improved. In the conventional method of coating the entire surface of the first grid electrode G1 or the second grid electrode G2 by plating or vapor deposition, B is initially set.
Although it has a diffusion and absorption effect of a, it is saturated immediately, and even if the coating film is thickened by that amount, the coating film peels off. The cause of the defective image is that each through hole T
Since the stray is generated from the peripheral portion of H, it is wasteful and uneconomical also for the purpose of suppressing this stray. In this respect, in the present invention, since the Ba diffusion absorber SA made of an expensive material is locally pressure-bonded only around the inner wall of each through hole TH, the thick film can be efficiently provided in the main part, The effect of diffusion and absorption of Ba is large, the productivity is good, the cost is economical, the resource is saved, and the life is long.

Next, FIG. 14 shows an example of the fluorescent screen 4 and the shadow mask 5 in detail. The fluorescent screen 4 formed on the inner surface of the panel portion has a light absorbing strip 224 extending vertically without interruption. A large number of light-absorbing strips 2 arranged in parallel in the horizontal direction.
A plurality of fluorescent strips 225R (red), each of which has a different emission color from each other and which extends without interruption over the entire vertical direction,
A large number of 25 G (green) and 225 B (blue) are arranged in a fixed order in the horizontal direction, and are arranged corresponding to the fluorescent screen 4 in a curved surface corresponding to the inner surface of the panel, and are arranged over the entire vertical direction. Slot-like through holes 228 that are elongated in the vertical direction corresponding to the fluorescent strips 225 that extend without cuts and that are formed in large numbers through the bridge portion 229 in the vertical direction are arranged in a row at a predetermined pitch in the horizontal direction. The shadow mask 5 is shown.

Further, as another shape of the phosphor screen 4, as shown in FIG. 15, dot-shaped phosphor fine dots 226R (red), 226
It has G (green), 226B (blue), and a light absorption film 227 filling the surroundings.

The shadow mask 5 is made of a steel plate material, an amber material having a small coefficient of thermal expansion, or the like. Further, although not shown, the shadow mask 5 may be covered with, for example, bismuth, which suppresses thermal expansion. Further, instead of the slot-shaped through hole 228, a round through hole is also used.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and it goes without saying that various modifications can be made without departing from the scope of the invention. . For example, in the above embodiment, as shown in FIG. 2 (b), the cylindrical Ba diffusion absorber SA was inserted into the through hole TH ', but since a material having good malleability is used, it may be spherical or granular. The shape before insertion is not particularly limited. Further, it is preferable to provide the tapered portions TP on the upper and lower portions of the through hole TH because the Ba diffusion absorber SA can be firmly fixed and the generation of stray from the peripheral portion of the through hole TH is suppressed. It is not always necessary to provide the tapered portion TP, and for example, the tapered portion TP may be provided only on the side facing the cathode electrode. Further, the Ba diffusion absorber SA is not necessarily provided only in the through hole TH of the electrode base body GS, and may be provided slightly protruding on the surface of the electrode base body GS. Furthermore, the electron gun of the present invention is
Not only cathode ray tube (CRT) but also color picture tube (CPT) and color display tube (CD
T), a projection cathode ray tube (PRT), and the like, and can be applied to all electron guns provided in an electron tube having a cathode electrode that emits thermoelectrons.

[0057]

As described above, according to the present invention,
A material that locally diffuses and absorbs Ba scattered from the cathode electrode around the inner wall of the through hole including the peripheral portion of the through hole through which the electron beam serving as the stray generation source of the first grid electrode or the second grid electrode of the electron gun passes Since it is provided in the, it is possible to suppress the occurrence of stray in the peripheral portion of the through hole,
The image quality is improved and the withstand voltage performance is also improved. In addition, since the above-mentioned expensive material is provided only in the main part, it can be efficiently provided with a thick film thickness, so that the effect of diffusion and absorption of Ba is large,
Moreover, it has high productivity, is economical, contributes to resource saving, and has a long life.

[Brief description of drawings]

1A is a plan view of a first grid electrode of an electron gun according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along the line AA of FIG.

FIG. 2 is a process sectional view showing the method of manufacturing the electron gun of the embodiment of the present invention.

FIG. 3 is a sectional view of a color cathode ray tube to which the present invention can be applied.

FIG. 4 is a sectional view showing a main part of an electron gun to which the present invention can be applied.

5 is a characteristic diagram of the electron gun shown in FIG.

FIG. 6 is a characteristic diagram of the electron gun shown in FIG.

FIG. 7 is a sectional view of a main part of another electron gun to which the present invention can be applied.

FIG. 8 is a sectional view of a main part of still another electron gun to which the present invention can be applied.

FIG. 9 is a sectional view of a main part of still another electron gun to which the present invention can be applied.

FIG. 10 is a partially cutaway perspective view of a main part of still another electron gun to which the present invention can be applied.

FIG. 11 is a partially cutaway perspective view of a main part of still another electron gun to which the present invention can be applied.

FIG. 12 is a partially cutaway perspective view of a main part of still another electron gun to which the present invention can be applied.

FIG. 13 is a front view, side view, rear view and plan view of still another electron gun to which the present invention can be applied.

FIG. 14 is a partially cutaway perspective view showing essential parts of an example of a fluorescent screen and a shadow mask of a cathode ray tube to which the present invention can be applied.

FIG. 15 is a plan view showing a main part of another phosphor screen of a cathode ray tube to which the present invention can be applied.

[Explanation of symbols]

G1 ... 1st grid electrode, G2 ... 2nd grid electrode, G
S ... Electrode base, TH ... Second through hole, SA ... Ba diffusion absorber, TH '... First through hole, TP ... Tapered portion, LG ...
Lower guide, LP ... Lower punch, UG ... Upper guide, UP ... Upper punch, t ... Thickness of electrode substrate, SA '... Surplus portion.

Claims (2)

[Claims] 1. An electron gun including a cathode electrode, a first grid electrode and a second grid electrode, wherein
An electron gun, wherein a material for diffusing and absorbing barium is provided around an inner wall of a through hole through which an electron beam of at least one of the grid electrode and the second grid electrode passes. 2. A first through hole, which is slightly larger than the inner diameter of the completed second through hole through which the electron beam passes, is formed at a predetermined position of the electrode base body which becomes the first grid electrode or the second grid electrode. 1 step, a second step of placing a material for diffusing and absorbing barium in the first through hole, a third step of crimping the material around the inner wall of the first through hole,
A fourth through hole is formed in the substantially central portion of the material.
A method of manufacturing an electron gun, comprising: