JPH01176638A - Electron gun for color picture tube - Google Patents

Abstract

PURPOSE:To design a high resolution and high reliability by disposing a 3rd electrode around a 2nd electrode of an electron gun, having a 1st electrode and the 2nd electrode, for a color picture tube. CONSTITUTION:An electron lens for focusing electron beams 111R, 111G, and 111B on the screen surface of a color picture tube is constituted with a 1st electrode 127 of a low potential and a 2nd electrode 128 of a high potential. A 3rd electrode 1 of a potential lower than that of the 2nd electrode is disposed around the 2nd electrode 128. The electron beams 111R, 111G and 111B passing near the 3rd electrode 1 are bent due to deflection electric field formed with the 3rd electrode 1 and the 2nd electrode 128 and in the end the multiplicity of electron beams 111R, 111G and 111B converge near the surface of a screen. As a result, beam passage holes 137R, 137G, 137B, 138R, 138G, 138B need not be displaced and therefore the beam passage holes can be enlarged to the limit of manufacturing electrodes. This enables to obtain an electron gun of a high resolution and high reliability and of much practical advantage.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an electron gun for color picture tubes.

(Prior Art) In general, a shadow mask type color picture tube consists of at least a screen section, a mask section, an electron gun section, an envelope surrounding these, and a deflection system for deflecting electron beams, which are emitted from the electron gun section. A plurality of electron beams are converged near the mask portion or the screen portion, and are caused to collide with corresponding phosphors provided on the screen to emit light. Therefore, a large number of groups of a plurality of phosphors forming one group are formed on the screen at predetermined intervals in correspondence with a plurality of electron beams. Conventionally, a method for concentrating the beam near the screen portion in such a cathode ray tube has been disclosed, for example, in U.S. Pat.
No. 57106, U.S. Patent No. 2849649, U.S. Patent No. 3772554 @ Mei III, U.S. Patent No. 4058753 Mei II, Japanese Patent Publication No. 49-5591
Several proposals have been made in publications such as the No. As proposed in U.S. Patent No. 3,772,554,
A common method is to decenter the coaxial cylindrical electrode that forms the main lens section of the electron gun, thereby concentrating the beam near the screen section. This method is extremely easy to manufacture the cylindrical electrode of the electron gun and assemble the electron gun itself, and is an extremely excellent method for mass production.

On the other hand, in cathode ray tubes such as color picture tubes, there is a strong demand to improve resolution by reducing the diameter of the beam spot on the screen, so a high-performance electron gun is required. Such an electron gun generally consists of a part that generates an electron beam and a main lens part that accelerates and focuses the electron beam.One effective means of improving the performance of an electron gun is to improve the performance of the main lens part. One example is how to do it. Most of the main lens parts are formed by coaxially arranging a plurality of electrodes having apertures using electrostatic lenses and applying a predetermined potential.

There are several types of such electrostatic lenses depending on the electrode configuration, but basically they are made by increasing the electrode aperture diameter to form a large-diameter lens, or by increasing the distance between the electrodes to achieve a gradual potential change. Lens performance can be improved by forming a long focal length lens. However, since it is generally used sealed in a thin glass cylinder, firstly, the aperture of the electrode, that is, the lens aperture, is physically limited, and secondly, the focused electric field formed between the electrodes is not affected by other electric fields. Therefore, the distance between the electrodes is limited. Therefore, if only the lens performance of the main lens part is Im and the aperture diameter of the two cylindrical electrodes is maximized within the practical range, there will be no room to decenter the axis of the cylindrical electrode, and the axis will be decentered and placed near the screen part. Beam cannot be focused.

Figures 6 to 8 show a conventional in-line color picture tube, with Figure 6 being a schematic side view, Figure 7 being a Y-Z side view of its neck, and Figure 8 being an electronic picture tube. x in the gun section
-Z sectional view.

In FIG. 6, the color picture tube 100 has a screen surface 10.
1, a neck 104 connected to the side wall 112 of the face plate 102 via a funnel 103, an electron gun 105 housed in the neck 104, and an outer wall extending from the funnel 103 to the neck 104. Deflection bag @106 attached to
A shadow mask 107 having a plurality of apertures 108 facing the screen 101 at predetermined intervals, a conductive material 111109 uniformly applied to the inner wall of the funnel 103 up to a part of the neck 104, and a conductive material 111109 applied to the outside of the funnel. conductive film 109 and funnel 10
3 and an anode terminal (not shown) provided on a part of the electrode. Red, green, and blue phosphors 1 are provided on the screen surface 101.
10 is applied in a striped manner, and the electron gun 10
Three electron beams 111R, 111G, 11 emitted from 5
1B is selected by the shadow mask 107, and causes each phosphor to emit light by impact. In FIGS. 7 and 8, the electron gun 105 has a plurality of electrodes to be described later and a plurality of insulating supports 122 supporting these, and has a glass cylindrical neck 10.
It is enclosed in 4.

The plurality of electrodes generate three electron beams 111R, 1 that strike the red, green, and blue phosphors on the screen, respectively.
Cathodes 124R, 124G, 124B arranged in a row and containing heaters 123R, 123G, 123B of 3111 for generating 11G, 111B, and these three cathodes 124R, 124G.

124B, a first grid 125, a second grid 126, a third grid 127 serving as a first electrode, and a third grid 127 serving as a second electrode. 4 grid 1
28 and a convergence electrode 129, each of which is implanted and fixedly supported in this order on the insulating support 122, except for the convergence electrode 129. The convergence electrode 129 is welded and fixed to the fourth grid 128, and a valve spacer 130 is attached to its side wall to apply a high voltage E of about 25 kV to the anode terminal (not shown) through the internal conductive WA 109. ing. Valve spacer 130 serves to secure electron gun 105 within neck 104 . For electrode potentials other than the convergence electrode 129 and the fourth grid 128, a predetermined potential is applied from the outside through a stem bin 131 provided at the bottom of the neck 104. First grid 125 and second grid 1
26 is a flat plate electrode arranged close to each other, the third grid 127 is made up of two cup-shaped electrodes 132 and 133 arranged close to the second grid 126 and joined together, and the fourth grid 128 is formed from the third grid 127. Consisting of two cup-shaped electrodes 134 and 135 placed a predetermined distance apart and joined together, the convergence electrode 129 is connected to the fourth grid 12.
It consists of one cup-shaped electrode 136 welded and fixed to 8.

Three circular electron beam passage holes corresponding to each electron beam are provided on the bottom surface of the cup-shaped electrode and the plate-shaped electrode of each of the grid electrodes and the convergence electrode 129, respectively.

The beam passage holes of the first grid 125 and the second grid 126 are relatively small, and the beam passage holes 136R, 136 of the third grid 127 facing the second grid 126 are relatively small.
G, 136B are larger than that, and the beam passing holes 137R, 137G1 of the third grid 127 facing the fourth grid 128 and the beam passing holes 137R, 137G1 of the fourth grid 128 are larger.
137B.

138R, 138G, 138B, 139R, 139G,
139B has a relatively large diameter d, and the beam passing holes 140R, 140G, and 140B of the convergence electrode 129 are smaller than that. A control element as shown in Japanese Patent Publication No. 51-26208@ is provided near the beam passing hole of the convergence electrode 129, so that the three beams can be well converged over the entire screen surface 101. There is.

The center passage hole among the electron beam passage holes is aligned from the first grid 125 to the fourth grid 128,
The passage holes on both sides are from the first grid 125 to the third grid 1.
27, but the beam passing hole 138R on the surface of the fourth grid 128 facing the third grid 127,
138B are each offset slightly outward, creating an asymmetric electric field in this region.

In the above electrode configuration, the following potentials are applied to each electrode, for example. The cathode is held at a cut-off voltage of about 150 volts to which a modulating signal is applied, the first grid 125 being at ground potential and the second grid 126 being at about 700 volts.
An anode high voltage of about 6 kV is applied to the third grid 127 and about 25 kV to the fourth grid 128. When the above voltage is applied, the electron beams generated from the cathodes 124R and 124G 1124B are focused by a pre-focus lens formed between the second grid 126 and the third grid 127, and then proceed to the third grid 127. The beam is strongly focused by the main lens formed between the beam 127 and the fourth grid 128, and is imaged as a beam spot on the screen 101 at a predetermined position. At this time, the beams 111R and 111B on both sides are deflected toward the center beam due to the asymmetric electric field formed by the deviation of the beam passing holes of the third grid 127 and the fourth grid 128, and near the screen, the beams 111R and 111B on both sides are deflected toward the center beam. beams 111R1111B are concentrated at one point.

In such an electron gun, in order to improve the lens performance of the main lens portion, if the diameter of the beam passage hole of the third grid 127 is set to the maximum in practical use, the electrode of the fourth grid 128 cannot be manufactured.

The reason for this will be explained in more detail using FIG. 9. 9th
The figure shows the third grid 127 from line A-A in FIG.
This is a view looking at the fourth grid 128 side, and for convenience of explanation below, the eaves portion 141 of the cup-shaped electrode is not included in the explanation. When an electrode is enclosed within the neck 104, the distance between the inner wall of the neck and the electrode is large due to voltage resistance. requires a minimum of 111, so the outer diameter D of the electrode is equal to the inner diameter of the neck, then D
-Dn-2k.

and be physically restricted.

Next, the three beam passing holes must be arranged in a row, and the bridge widths Bc3 and Bc4 of the bridge part between the three beam passing holes and the bridge widths BS3 and Bs4 of the bridge parts on both sides are machined. Because there are manufacturing limits,
Each beam passing hole diameter D8 is maximum DB-1/3 [oo-2
(Bc3+8.)]-1/3 [D-2(Bc4+
(In the above equation, BB indicates the manufacturing limit width of 31s4.) However, the third grid 127 and the fourth grid 1
The cup-shaped electrodes on the opposing surfaces of 28 must be made even smaller because the beam passing holes on both sides must be deviated. If the above deviation amount is d, then D -1/3 [D -2 (Bc3+8,4)-
2 dlB e , and the diameter of the beam passage hole cannot be maximized in practice by d. The value of d may range from 200 μI to 300 μI, which is extremely wasteful.

In addition, if the main lens sections on both sides are made asymmetrical in order to concentrate the three beams on the screen, the electron beam focusing effect, which is the main purpose of the main lens section, will become asymmetrical.
Comatic aberration occurs in the electron beams on both sides, and the beam shapes of the central electron beam and the electron beams on both sides of the screen are different, which causes a problem of deteriorating the resolution of the color picture tube.

Generally speaking, in addition to the above-mentioned focusing means performed by deflecting the beam passing hole, as shown in Japanese Patent Publication No. 49-5591, etc., a convergence electrode is provided at the end of the fourth grid 128 (on the screen side). It is also known to place an electrostatic deflection plate separately without arranging an electrostatic deflection plate, and to supply a new deflection potential from outside the tube. As a result, the total length of the color picture tube becomes longer, which is undesirable because it increases the economic burden in terms of mass production and transportation.

Furthermore, as the total length of the color picture tube becomes longer, the electro-optical magnification of the electron lens deteriorates, the beam spot diameter on the screen deteriorates, and the resolution deteriorates. Furthermore, it is not economical to have to supply a new deflection potential from outside the tube, and since the deflection potential at the bottom is a very high voltage that is only slightly lower than the high potential of the anode, it is necessary to supply such a high voltage inside the tube. In terms of withstand voltage, it is not preferable to route the

(Problems to be Solved by the Invention) The purpose of the present invention is to solve the problem of not being able to increase the diameter of the electron beam passing hole of the electron gun, that is, the diameter of the electron lens to the limit of electrode manufacturing, and the problem of resolution deterioration due to aberrations caused by the asymmetric main lens part. , or the problems of economic deterioration and resolution deterioration due to the increase in the total length of the color picture tube, and furthermore, the problem of having to supply it separately from outside the tube (ζ). The object of the present invention is to provide an electron gun for a color picture tube that has high resolution, high reliability, excellent economic efficiency, and is highly practical.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention includes a plurality of cathodes that generate a plurality of electron beams, and a plurality of cathodes arranged in the traveling direction of the electron beams in this order. In a color picture tube electron gun comprising at least a first electrode with a low potential and a second electrode with a high potential, a third electrode with a lower potential is provided on the outer periphery of the second electrode. It is characterized by

(Function) In the present invention, the first electrode and the second electrode constitute an electron lens that focuses an electron beam on the screen surface of a color picture tube. The electron beam passing near the third electrode is the 31st! The electron beams are bent due to the deflection electric field formed by the poles and the second electrode, and eventually the plurality of electron beams come to be concentrated near the screen surface. Therefore, since there is no need to deviate the beam passing hole of the electron lens section, the beam passing hole can be enlarged to the limit of electrode manufacturing, making it possible to form a large diameter lens, and there is no need to form an asymmetric main lens section. Aberrations are less likely to occur. Alternatively, by arranging an electrostatic deflection plate, there is no need to separately supply a deflection potential from outside the tube.

(Example) The present invention will be described in detail below with reference to the drawings. FIG. 1 is a YZ side view of the neck portion of a color picture tube embodying the present invention, and FIG. 2 is a sectional view taken along line X-7. FIGS. 1 and 2 correspond to FIGS. 7 and 8, respectively, and the same parts are given the same numbers.

In Figures 1 and 2, three heaters 123R1123
G, 123B and cathode 124R, 124G, 124B
The configurations of the first grid 125, the second grid 126, the third grid 127, which is the first electrode, and the fourth grid 128, which is the electrode, are the same as in the conventional example. Two beam passing holes 137R, 1
37G.

137B hole diameter and pitch SQ3 and fourth grid 12
8 three beam passing holes 138R1138G, 138B
The pore diameter and pitch are exactly the same, and each has a large pore diameter that is at the manufacturing limit. Furthermore, in this embodiment, a third electrode is attached to a part of the side wall of the electrode 134 constituting the fourth grid 128.
electrodes 1 are arranged. This third electrode 1 is
- 4th grid 1 parallel to the Z plane and perpendicular to the X-2 plane
The potential of the third grid 127 is supplied to this electrode 1 through the connector 2. In this embodiment, a part of the side wall of the cup-shaped electrode 128 has an opening 3, and the third electrode 1 is fixed in alignment with this opening 3.

By forming such a configuration and applying the aforementioned predetermined potential to each electrode, the cathodes 124R1124G, 124B
The electron beam 111R is emitted from the electron beam 111R.

Lenses 111G and 111B each receive the same lens action as in the prior art and reach the main lens section 4. Unlike the conventional example, the main lens section 4 has a large diameter lens with three main lenses 5R15G and 5B, and the main lenses on both sides are not distorted as in the conventional example. Therefore, each electron beam moves toward the screen to be focused on the screen due to the action of a high-performance lens, but the electron beams 111R1111B on both sides that have passed through the main lens section 4 are at a low potential due to the third electrode 1. The electron beam is slightly deflected in the direction of the central electron beam 111G. This deflection action is not a deflection that also serves as a focusing action by distorting the main lens as in the past, but is purely a deflection without the equipotential lines 6 being distorted, so the aberration with respect to the electron beam is less than that of the conventional example. Very small.

Thus, according to this embodiment, the electron lens aperture of the electron gun,
That is, the diameter of the electron beam passing hole can be made as large as possible, thereby improving the performance of the electron lens and the resolution of the color picture tube.

Furthermore, aberrations caused by concentrating a plurality of electron beams can be suppressed to a small level, and concentration can be performed without increasing the overall length of the electron gun, that is, the color picture tube. Further, there is no need to separately supply a deflection potential from outside the tube, and an economical color picture tube can be provided.

In this embodiment, a pi-potential type electron gun, which is the most common type, has been described, but it goes without saying that the present invention is not limited to this, and can be applied to a uni-potential type electron gun and other electron guns. In the above embodiment, the fourth grid 1
28 has an opening 3 in a part of the side wall, and this opening 3.
Although the third electrode 1 is disposed in the third electrode 1, the present invention is not limited to this, and may be implemented with other structures. Of course, as shown in FIG. 3, a partition plate 7 having the same potential as the fourth grid 128 can be placed within the electrode of the fourth grid 128 to separate the central electron beam.

4 and 5 relate to a second embodiment of the present invention and correspond to FIGS. 1 and 2, respectively, and the same elements are given the same reference numerals. In FIGS. 4 and 5, the electrodes are in the first grid 125, the second grid 126, and the third grid.
Grid 127, 4th grid 128, 5th grid 2
01, 6th grid 202, 7th grid 203, 8th grid
It consists of a grid 204, a ninth grid 205, and a convergence electrode 129.

The fifth grid 201 forms a first electrode, and the sixth grid 202, seventh grid 203, eighth grid 204, and ninth grid 205 form a second electrode. The first grid 125 and the second grid 126 are supplied with the same potential as in the first embodiment, and the third grid 125 is supplied with the same potential as in the first embodiment.
7 and the fifth grid 201 are kept at the same potential and supplied with a focus voltage of about 8 kV, and the fourth grid 128 is connected to the second grid 126 and supplied with a low potential of about 500-700V. Next, the sixth grid 202, the seventh grid 203, and the eighth grid 2041.1m each consisting of relatively thin plate-shaped electrodes have G and t of about 12 kV, 16.
Resistor 1 with potentials of 5kV and 21kV placed nearby
1 as a divided potential of the anode high voltage of approximately 25 kV. An anode voltage is applied to the ninth grid 205 and the convergence electrode 129. In such an electrode configuration, a weak unipotential lens is formed by the third grid 127, fourth grid 128, and fifth grid 201 to perform auxiliary focusing, and the U.S. has a gentle potential gradient from the fifth grid 201 to the ninth grid 205. Patent No. 28
An extended field lens as shown in US Pat. No. 5,9378 is formed to provide main focusing.

Although it is well known that such an extended electric field lens improves lens performance, the lens performance can be roughly improved by enlarging the beam passage aperture diameter, that is, the lens aperture diameter. Therefore, even in a color picture tube having such an electron gun, it is not preferable to concentrate the three beams on the screen by deviating the diameter of the beam passing hole as in the conventional example.

Therefore, as shown in FIGS. 4 and 5, a third electrode 1a is arranged on a part of the side wall of the seventh grid 203, and the potential of this electrode 1a is supplied from the sixth grid 202. In such an extended electric field lens, the fifth grid 201, the sixth grid 202, the seventh grid 203, and the eighth grid 20
4. Since the potential difference between each grid of the ninth grid 205 is very small, the sixth grid 2, which has a lower potential than the seventh grid 203, is placed on a part of the side wall of the seventh grid 203.
Even if the third electrode 1a, which has a potential of 02, is provided, the electric field of the main lens is not greatly disturbed, and a deflection electric field is formed only in the seventh grid 203 and only in the electron beams on both sides. , large aberrations that occur in the conventional method by shifting the beam passage hole do not appear in the electron beam. In this way, the diameter of the beam passing hole can be made as large as possible, improving the lens performance, and making it possible to concentrate the three beams on the screen. Further, at the expense of economy, the potential to be supplied to the third electrode 1a may be supplied from outside the tube, or the potential obtained by resistance division from the third electrode 1a may be used.

[Effects of the Invention] As explained in detail above, according to the present invention, high resolution,
It is possible to provide an electron gun for color picture tubes that is highly reliable and economically efficient.

[Brief explanation of the drawing]

1 is a side view of an electron gun for a color picture tube according to a first embodiment of the present invention, FIG. 2 is a sectional view along the X-Z axis of FIG. 1, and FIG.
The figure is an x-Z axis sectional view of an electron gun for a color picture tube according to another embodiment of the present invention, and FIGS. 4 and 5 are views corresponding to FIGS. 1 and 2 of still another embodiment, Figure 6 is a sectional view of a color picture tube, Figures 7 and 8 are diagrams corresponding to Figures 1 and 2 of a conventional electron gun for color picture tubes, and Figure 9 shows the state of the beam passage hole. It is a diagram. 1.1a...Third electrode

Claims (1)

[Claims] For a color picture tube, comprising at least a plurality of cathodes that generate a plurality of electron beams, a first electrode with a low potential and a second electrode with a high potential, which are arranged in this order in the traveling direction of the electron beams. An electron gun for a color picture tube, characterized in that a third electrode having a lower potential than the second electrode is provided on the outer periphery of the second electrode.