JPH0145075Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electron gun for a color picture tube, and in particular to the structure of an electrode forming a main electron lens of an electron gun that is attached to a shadow mask type color picture tube and emits a plurality of electron beams. be.

A shadow mask type color picture tube accelerates and focuses the thermoelectrons emitted from multiple electron beam sources of an electron gun installed in the network into multiple electron beams, and passes these multiple electron beams through a shadow mask to fluoresce. It is designed to illuminate the body screen and reproduce color images.

Various types of electron guns are known, but all of them use thermoelectrons emitted from an electron beam source, ie, a cathode, to become an electron beam, which is then accelerated and focused onto a phosphor screen by a main electron lens. is being done. Generally, an electrostatic lens is used as the main electron lens, and the characteristics of the electrostatic lens are determined by the diameter of the lens, similar to optical lenses.

Generally, the maximum diameter of the main electron lens is determined by the inner diameter of the picture tube's neck and the structure of the electron gun. For example, when emitting electron beams arranged in a row from an electron gun consisting of electrodes each having an independent structure, the diameter of the main electron lens is approximately
30%, and when emitted from an electron gun consisting of an integrated structure electrode, the diameter of the main electron lens is limited to about 28%, which cannot be a sufficient diameter due to its characteristics.

On the other hand, a shadow mask type color picture tube reproduces a color image by concentrating three electron beams on a phosphor screen and operating them both horizontally and vertically using a deflection device. In this case, convergence refers to convergence of three electron beams on the phosphor screen, and in general, the smaller the net diameter, the better the characteristics are obtained, and the power required to deflect and scan the electron beams, i.e. The deflection power is proportional to the neck diameter, and the smaller the neck diameter, the less power is required.

As mentioned above, electron beam focusing, convergence, and deflection scanning are interrelated with each other with respect to the net diameter, and the current situation is that a compromise between the two is generally used in the design, especially in the case of recent color picture tubes. The diameter of the net is becoming ultra-thin from the conventional 29.1 mm to 22.5 mm due to the need to conserve resources and power. Naturally, as the net diameter becomes smaller, the electron gun also becomes smaller and accuracy becomes more demanding.

Next, the structure of a shadow mask type color picture tube will be explained with reference to FIG.

In other words, the shadow mask type color picture tube produces red, green, blue, and
A panel 2 is formed by adhering a phosphor screen 1 on which phosphor layers emitting light in each color are regularly provided in the shape of dots or bands, and a neck 4 and a stem pin connected to this panel 2 via a funnel 3. An electron gun 8 emits three electron beams 7 into a high-vacuum envelope consisting of a stem 6 implanted with a stem 6, and the electron gun 8 emits three electron beams 7 into a predetermined phosphor layer on a phosphor screen 1. Shadow mask 9 to shoot at
and a deflection device 10 attached to the outer wall from the funnel 3 to the neck 4. This deflection device 10 directs the electron beam 7 to the phosphor screen 1.
The phosphor screen 1 is deflected and scanned in the horizontal and vertical directions to reproduce a color image on the phosphor screen 1.

The electron gun 8 installed in such a shadow mask type color picture tube is roughly divided into an independent electrode electron gun and an integrated electrode electron gun. An example of the structure of an integrated electrode electron gun that is currently commonly used is as shown in FIG. 2. As shown in FIG. A third grid 14 consisting of electrode elements 14 ₁ and 14 ₂ , a fourth grid 15 having a cylindrical shape with a bottom, a convergence electrode 16 shown by a broken line, and glass for implanting and supporting implant pieces provided on each of these electrodes, etc. It consists of an electrode support 17 consisting of. The cathodes 11 are each independent corresponding to three electron beams, but the other electrodes, namely, the first grid 12, the second grid 13, the third grid 14, and the fourth grid 15 are integrated into three electrodes, respectively. The structure includes holes through which electron beams pass.

In the electron gun 8 having the above structure, the cathode 11, the first
The grid 12 and the second grid 13 are called a triode, and they emit thermoelectrons and form an object point for a main electron lens, which will be described later.A main electron lens is formed between the third grid 14 and the fourth grid 15. , adapted to concentrate and focus the electron beam onto a phosphor screen. In the electron gun shown in FIG. 2, the passage holes for three electron beams are formed in the integrated electrode. Assembly accuracy is superior to independent electrode electron guns. Moreover, the center axis interval 18 of the passage hole portion is also constant.

However, as shown in FIGS. 3 and 4, for example, the third grid 14 of the electron gun 8 described above has a bottom 21 of the electrode element ₁₄₁ for use with an electron beam for injecting the electron beam from the triode. Passing hole portions 22, 23,
24 is drilled, so there is no problem. However, the electrode element 14 ₂ has a large-diameter electron beam passage hole 32 forming a main electron lens in the bottom part 31;
33, 34 are bored, and these passage holes 32, 3
3 and 34 are approximately perfect circular shapes, and the passage holes 32,
The diameter 35 of 33, 34 cannot be made sufficiently large due to the center axis spacing 36 and the width of the bridge portions 37, 38. Further, the passage holes 32, 33, and 34 include an electrostatic lens formed in the central passage hole 32,
A wall portion 3 for preventing the electrostatic lenses formed in the passage holes 33 and 34 on both sides from interfering with each other.
2 ₁ , 33 ₁ , 34 ₁ , that is, burring portions are provided independently. In the figure, 40 is a planting piece, and 14 _1a and 14 _2a are flange parts. The length 39 of this wall portion is generally the same as that of the passage hole portions 32, 33, 3
1/2 or more of the diameter of 4 is required. Also,
The width of the bridge portions 37 and 38 is the same as that of the wall portions 32 ₁ , 33 ₁ ,
Due to the burring process of 34 ₁ , it cannot be narrowed below a certain level, and the limit is the electrode element 14 ₂
The thickness of the metal plate forming the burring process, the strength of the burring jig, especially the die, the wall portion 32 ₁ ,
It is determined by the length 39 of 33 ₁ , 34 ₁ , etc. Therefore, it is impossible to make the widths of the bridges 37, 38 extremely narrow and to enlarge the diameters 35 of the passage holes 32, 33, 34. For example, 22.5mm
When the length 39 of the wall portions 32 ₁ , 33 ₁ , 34 ₁ is set to 3 mm or more in the electrode for the main electron lens for the ultra-thin neck of φ, the diameters of the passage holes 32 , 33 , 34 are as follows.
It will be approximately 3.5mm to 3.9mmφ. It is generally said that the spherical aberration of a lens is inversely proportional to the cube of its diameter, so a main electron lens formed by such a small diameter passage hole has the disadvantage of extremely large spherical aberration. . In addition, the wall portion 32 ₁ ,
Mechanical distortion is likely to occur in the electrode element 14 ₂ during the process of forming 33 ₁ and 34 ₁ , and changes in the electrode element 14 ₂ itself occur during the aging process of the color picture tube and the heating process during operation. Furthermore, there is also the drawback that the spherical aberration of the main electron lens tends to increase.

One way to eliminate the drawback that the passage holes 32, 33, and 34 described above cannot be enlarged is to replace the electrode element opposite the fourth grid with the fifth grid.
Structures such as those shown in Fig. 6 and Fig. 6 have been considered.

That is, the electrode element 14' ₂ has electron beam passage holes 42, 4 forming a main electron lens in the bottom part 41.
The diameters 45 of the passage holes 42, 43, 44 for enlarging the main electron lens are approximately equal to or slightly larger than the center axis spacing 46. Furthermore, the passage holes 42, 43, 44
There are wall portions 43 ₁ and 44 1, that is, burrings, to prevent the electrostatic lens formed in the central passage hole 42 and the electrostatic lenses formed in the passage holes 43 and ₄₄ on both sides from interfering with each other. A section has been established. These wall portions 43 ₁ , 44 ₁ have passage hole portions 42 , 4
3 and 44 are approximately equal to or slightly larger than the distance between the center axes of the electron beams, so they are not provided at opposing positions. Instead, metal plates 47 and 48 are provided slightly lower than the bottom portion 41 to correct coma aberration of the main electron lens. The reason why these metal plates 47 and 48 are provided slightly lower than the bottom part 41 is that among the passage holes 42, 43, 44, especially the central passage hole 43
This is to remove the distortion of the main electron lens that occurs due to the non-circular shape of the main electron lens. In the figure, 50 is a flange portion necessary for press working.

However, in the electrode element 14' ₂ , the passage holes 42, 43, and 44 are first formed as one large hole, that is, a communicating hole, and then the metal plates 47 and 48 are fixed by means such as welding to form an independent structure. A hole is formed. Normally, when press-forming a thin plate with a thickness of about 0.4 mm, there is no bridge between the passage holes 42, 43, and 44, and for this reason, the accuracy of the finished electrode element is compared to one with a bridge. This causes significant deterioration, such as twisting. Also,
The metal plates 47 and 48 are not necessarily arranged with high precision, and the precision of their combination is still a problem. Furthermore, when assembling an electron gun, there is a problem in that it is easily distorted by mechanical stress from an assembly jig, etc., and the effect of increasing the size of the passage hole cannot be fully exhibited.

The present invention has been devised in view of the above-mentioned drawbacks and problems, and an object of the present invention is to provide an electron gun for a color picture tube that has excellent mechanical precision and is capable of improving electron beam focusing performance.

Next, an embodiment of an electron gun for a color picture tube according to the present invention will be described with reference to FIGS. 7 to 10.

That is, the color picture tube _electron gun ₅₈ , as shown in FIG. Consisting of a grid 64, a fourth grid 65 also made of a perforated plate-like member, a convergence electrode 66, and an electrode support 67 made of glass or the like that supports the implantation pieces provided on each of the electrodes other than the convergence electrode 66. . The cathodes 61 are independent corresponding to the three electron beams arranged in a row, but the other electrodes, namely the first grid 62, the second grid 63, the third grid 64, and the fourth grid 65 are Each of the integrated electrodes has a structure in which three electron beam passage holes are formed.

In the electron gun 58 having such a structure, the cathode 6
1. The first grid 62 and the second grid 63 are referred to as a triode, which emits thermionic electrons and forms an object point for a main electron lens, which will be described later. is formed,
The electron beam is focused onto a phosphor screen. The electron gun in Figure 7 is 3
Since the passage hole for the electron beam is formed in the integrated electrode, the assembly accuracy after implantation and fixation on the electrode support 67 via the implantation piece is superior to that of an independent electrode electron gun. However, the passage hole portion, that is, the center axis interval 68 of the electron beam is also constant.

Next, the structure of the third grid of the electron gun 58 will be explained with reference to _FIGS . Holes 72, 73, 74 are bored, the openings have a flange 75, and at least the inner wall of the side wall 76 is formed with passage holes 72, 7.
It is formed from an envelope curved surface of cylinders 72 ₁ , 73 ₁ 374 ₁ which are coaxial with the axes of the cylinders 3 and 74 and have a common portion 77, and an implant piece 80 is fixed to the outer wall by means such as welding.

Next, the flange portion 7 of the bottomed cylindrical support member 64 ₁
The perforated plate-like member 64 ₂ placed and fixed on the electrode element 14' ₂ shown in FIGS. 5 and 6 will be described _below .
44, wall portions 42 ₁ , 43 ₁ , 44 ₁ , metal plate 47 ,
48, and the conditions to be met are as follows, as shown in FIG.

(1) The thickness 89 is close to 1/2 of the diameter 85 of the passage holes 82, 83, 84, which means that the wall portions 82 ₁ , 83
_The length will be _1,841 .

(2) The diameter 85 of the passage holes 82, 83, 84 is approximately equal to or larger than the electron beam interval 68.

(3) The bridge portions 87 and 88 are perforated plate-like members 64 ₂
is formed integrally with the height 90 and the thickness 8
be lower than 9 by a specified amount.

(4) Overall mechanical precision and mechanical shock resistance.

Regarding the first condition, for an ultra-thin neck with a neck diameter of 22.5 mm, the diameter of the passage holes 82, 83, and 84 is 8.
5 is about 3.5 mm, so about 2 to 4 mm is sufficient. This value can be formed by a conventionally known pressing technique, or by stacking a plurality of perforated plate members.

Regarding the second requirement, the diameter of the main electron lens should be increased so as not to deteriorate the focusing characteristics of this lens, and the diameter is determined by the type of color picture tube.

The third requirement is that the bridge portions 87 and 88 are formed integrally with the perforated plate-like member ₆₄₂ , and are formed a predetermined amount lower than the surface facing the fourth grid, so that the central passage hole The electrostatic lens formed on the part is in the longitudinal direction and in the transverse direction (direction with the bridge part).
Both are formed smoothly, making it possible to reduce asymmetrical aberrations of the electron beam.

The fourth requirement is that unlike conventional electrodes, the bridge part is integrally formed from the beginning rather than a fixed metal plate, so mechanical strength and mechanical shock resistance are as shown in Figures 5 and 6. It is much better than the one in the picture.

That is, the overall shape of the perforated plate member ₆₄₂ is almost the same as the conventional one except for the lack of a flange, but the shape of the passage hole is different from that of the conventional one. In the vicinity of the surface, three passage holes are communicated with each other to form one communication hole, and three passage holes are independent from the bridge parts 87 and 88. Such a structure is the fourth grid 6
The same applies to case 5.

In addition to the above-mentioned advantages, this embodiment has the advantage that it is hardly distorted by mechanical stress during assembly of the electron gun. As a result, the reference point (reference plane) during assembly can be selected at any point on the perforated plate-like member ₆₄₂ , so there is no restriction on the assembly method. For example, the reference point during assembly can be set not only on the passage hole but also on the outer wall, which facilitates automatic assembly.

Another advantage of this example is that it has excellent resistance to treatment by tumbling. That is, in general, in an electron gun, it is necessary to remove minute protrusions on the electrode surface in order to prevent a discharge phenomenon occurring between the electrodes.
To do this, a mechanical polishing process called tumbling is applied, but at this time the electrode is subjected to mechanical shock, especially in the case of conventional electrodes that do not have a bridge part or have a metal plate attached. Although the degree of distortion is large, this embodiment hardly suffers from such distortion.

Next, the specific dimensions of the electrode element are as follows: the distance between the electron beams 68 is 6.6 mm, the bridge portions 87, 88
The width of the passage hole portions 82, 83, 84 is 7.0 mm, the height 90 of the bridge portions 87, 88 is 1.5 mm, and the thickness 89 is 2 mm.

Next, FIG. 11 shows a perforated plate member 64' ₂ adapted to another embodiment of the present invention. In the figure, the same parts as in FIGS. 8 to 10 are designated by the same reference numerals, and will not be particularly described.

That is, the perforated plate-like member 64' ₂ has passage holes 82, 8.
The first having bridge parts 87 and 88 between 3 and 84.
The perforated plate member 94 ₁ and the passage hole portions 82', 83',
It is characterized in that it is formed from a second perforated plate-like member ₉₄₂ with which 84' is communicated. In this way, two perforated plate members 94 ₁ and 94 ₂ are made separately,
Integration has the advantage of facilitating machining.

Although the above embodiment mainly describes a bipotential electron gun that emits and focuses electron beams arranged in a row, the present invention is not limited to this, and can be applied to other types of electron guns as well. The perforated plate member is not placed and fixed on the cylindrical support member,
Of course, it is also possible to use this perforated plate-like member itself as an electrode.

As described above, the electron gun of the present invention completely solves the mechanical problems caused by enlarging the diameter of the main lens, and makes it possible to obtain an electron gun for color picture tubes with high precision and good focusing characteristics. can.

[Brief explanation of drawings]

1 is a simplified explanatory diagram of a color picture tube, FIG. 2 is a side view showing an example of a conventional electron gun for a color picture tube, FIG. 3 is a plan view of the third grid as seen from the fourth grid side, and FIG. The figure is a cross-sectional view taken along line A-A' in Figure 3, and Figure 5 shows an electrode element placed opposite the fourth grid of the third grid, which may be considered for the purpose of enlarging the passage hole. The plan view shown in Fig. 6 is
7 to 10 are views showing an embodiment of the electron gun for a color picture tube according to the present invention, and FIG. 7 is a side view. ,
FIG. 8 is a plan view of the third grid viewed from the fourth grid side, FIG. 9 is a sectional view of FIG. 8 taken along line C-C', and FIG. 10 is an exploded perspective view. 11th
The figure is an exploded perspective view of a perforated plate member adapted to another embodiment of the present invention. 8,58...electron gun, 12,62...first grid, 13,63...second grid, 14,64
... Second grid, 14 ₁ , 14 ₂ ... Bottomed cylindrical electrode element, 37, 38, 87, 88 ... Bridge portion, 47, 48 ... Metal plate, 64 ₂ , 64' ₂ ...
Perforated plate member, 64...Bottomed cylindrical support member.

Claims (1)

[Claims for Utility Model Registration] (1) A plurality of electrodes including an electrode group forming a main electron lens for converging and concentrating three electron beams arranged in a row on a phosphor screen, and these electrodes. In an electron gun for a color picture tube, at least one electrode forming the main electron lens includes a thick perforated plate-like member, and the perforated plate-like member supports the main electron lens. 1. An electron gun for a color picture tube, characterized in that it has a communicating hole portion having a diameter larger than the distance between the center axes of electron beams, and an independent hole portion formed through a bridge integrally formed with a perforated plate-like member. (2) A utility model registration request characterized in that the perforated plate-like member consists of a first perforated plate-like member having a communicating hole and a second perforated plate-like member having an independent hole. An electron gun for a color picture tube according to scope 1. (3) Utility model registration claim 1 or 2, characterized in that the communicating hole is formed in a portion opposite to another electrode forming the main electron lens.
Electron gun for color picture tube as described in . (4) An electron gun for a color picture tube according to claim 1 or 2, wherein the perforated plate member is mounted and fixed on the flange portion of the cylindrical support member.