JPH0552019B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electron gun for a cathode ray tube for focusing at least one, preferably more, electron beams, and in particular to its electrostatic lens structure and electrode support structure. It is.

[Technical background and problems of the invention]

A cathode ray tube is equipped with at least one electron gun, which forms an electron beam spot on a predetermined target. One of the extremely important factors that determines the performance of the cathode ray tube in this electron gun is the spot diameter of the electron beam on the target. It goes without saying that a smaller spot diameter on the target is more desirable, but this spot diameter is determined by the performance of the electron gun. Generally, an electron gun 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.

Most of the main lens parts are electrostatic lenses, which are formed by arranging a plurality of electrodes having openings coaxially and applying a predetermined potential. There are several types of such electrostatic lenses depending on the electrode configuration, but basically, the electrode aperture diameter is increased to form a large-diameter lens, or the distance between the electrodes is increased to create a gradual potential change. By forming a long focal length lens, lens performance can be improved. However, since electron guns for cathode ray tubes are generally used while being enclosed in a thin glass cylinder called a net, firstly the aperture of the electrodes, that is, the diameter of the lens, is physically limited, and secondly, the focused electric field formed between the electrodes is The distance between the electrodes is limited in order to avoid being affected by the electric field. Particularly when a plurality of electron guns are used in a line, such as in a color picture tube, the smaller the electron gun spacing S _g is, the easier it is to converge the plurality of beams, and it is advantageous in terms of deflection power. Therefore, the openings in the electrodes have to be made even smaller.

Therefore, while keeping the electron gun spacing S _g small, the electrode aperture is made as large as possible to widen the distance between the electrodes, and an auxiliary electrode is provided between the electrodes to shield the influence of the undesired electric field on the inner wall of the network. An electron gun is considered. In such an electron gun, the aperture diameter of the auxiliary electrode must be set sufficiently large in order to eliminate the influence of the electric field of the auxiliary electrode. Therefore, we would like to make the aperture diameter of the auxiliary electrode as large as the inner wall of the neck to make the distance between the electrodes sufficiently wide and create a high-performance electron gun, but in reality, the aperture diameter of the auxiliary electrode should be made as large as the inner wall of the neck. Therefore, the distance between the electrodes cannot be made sufficiently wide. This is because the insulating supports for supporting the electrodes are enclosed in the neck like the electrodes, and the aperture diameter of the auxiliary electrode is actually limited by the distance between the insulating supports.

[Purpose of the invention]

The present invention provides an electron gun for a cathode ray tube having the above structure, in which the aperture diameter of the auxiliary electrode can be increased up to the aperture diameter limited by the inner wall of the neck, and the distance between the electrodes is sufficiently increased to allow the lens of the main lens to The purpose is to improve performance and reduce the diameter of the spot focused on a given target.

[Summary of the invention]

The electron gun for a cathode ray tube of the present invention achieves the above object by having an electron gun having the above structure in which the insulating support for supporting the electrode is divided into two parts with the auxiliary electrode as a border.

[Embodiments of the invention]

The present invention will be described in detail below with reference to the drawings. Fig. 1 shows an example of an electron gun for a color picture tube embodying the present invention, Fig. 2a is a sectional view along the Y-Z axis of Fig. 1, and Fig. 2b is a sectional view along the X-Z axis. .

In FIG. 1, FIG. 2a, and FIG. 2b, the electron gun 1 has a plurality of electrodes, which will be described later, and a plurality of insulating supports 2a and 2b that support them. The plurality of electrodes are three electrodes for generating three electron beams 3a, 3b, and 3c that impinge on the red, green, and blue phosphor layers (not shown) of the phosphor surface as targets. A first cathode having an integrated structure includes cathodes 9a, 9b, 9c arranged in a row containing heaters 6a, 6b, 6c, and predetermined electron beam passage holes protruding from positions relative to these three cathodes. grid 1
1, 2nd grid 12, 3rd grid 13, 4th grid
It consists of a grid 14, a convergence electrode 15, and an auxiliary electrode 16 located between the third grid 13 and the fourth grid 14 and having one large opening, and is implanted and fixedly supported by the insulating supports 2a and 2b. ing. First grid 11 and second grid 12
is a flat plate-shaped electrode arranged close to the second grid 12, the third grid 13 is made up of two cup-shaped electrodes 23a and 23b arranged close to the second grid 12 and joined together, and the fourth grid 14 is composed of the third grid 13 The convergence electrode 15 consists of two cup-shaped electrodes 24a and 24b which are arranged and joined at a predetermined distance from the fourth grid 14.
It consists of two cup-shaped electrodes 25a. Three circular electron beam passage holes aligned with 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, respectively. The electron beam passing holes of the first grid 11 and the second grid 12 are relatively small, and the electron beam passing holes 33a, 33b, 33 of the third grid 13 facing the second grid 12 are relatively small.
c is larger than that, and the electron beam passage hole 43 on the side of the third grid 13 facing the fourth grid 14
a, 43b, 43c and the electron beam passage holes 34a, 34b, 34c, 44a of the fourth grid 14,
44b and 44c have the same diameter and relatively large diameter,
Electron beam passage hole 35 of convergence electrode 15
a, 35b, and 35c are smaller than that. The auxiliary electrode 16 consists of two cylindrical electrodes 26a, 26b, each of which is connected to the third grid 1.
3. Cup-shaped electrodes 23b, 2 of the fourth grid 14
One such auxiliary electrode containing 4a is shown in FIG. Further, a bulb spacer 17 is attached to the convergence electrode 15 to apply a high voltage of about 25 KV to an anode terminal (not shown). Such an electron gun is enclosed within a narrow glass cylinder neck 18, and a stem pin 19 is arranged at the bottom of the neck. This stem pin 19
supports and fixes the electron gun 1, and is adapted to be able to supply each electrode potential other than the convergence electrode 15 and the fourth grit 14 from the outside through a stem pin 19.

In the above electrode configuration, the parts from the heater to the third grid 13 and one of the auxiliary electrodes 26a are implanted and fixedly supported on a pair of insulating supports 2a, and the other electrode 26b of the auxiliary electrodes and the fourth grid 14 is implanted and fixedly supported by another pair of insulating supports 2b, and two auxiliary electrodes 26a,
26b is joined at its flange portions 30a and 30b, and the joined portion is fixed by welding to constitute the electron gun 1. Therefore, as shown in FIG. 1, the diameter of the auxiliary electrode 16 is not limited by the diameter DB of the pair of insulating supports, but can be maximized until it is limited by the inner wall diameter DN of the neck 18. It becomes possible.

Now, the operation of the above electron gun is as follows, for example. The cathode 9 is kept at a cut-off voltage of approximately 150V, to which a modulation signal is respectively applied. The first grid 11 is at ground potential and the second grid 12 is at approximately
700V is applied to the third grid 13, and approximately
An anode high voltage of about 25 KV is applied to the fourth grid 14, and about 16 KV, which is approximately an intermediate potential between the third grid 13 potential and the fourth grid 14 potential, is applied to the auxiliary electrode 16. In an electron lens having such an electrode structure in the main lens portion, the equipotential distribution is as shown in FIGS. 3a and 3b. Figure 3a is Figure 2a, Figure 3b is Figure 2b
The equipotential lines 20 are shown in the diagrams corresponding to the respective figures, and the electrode structure is shown in a simplified manner in order to explain the main lens portion of the electron gun. As can be seen from Figures 3a and 3b, the potential distribution is almost disordered in the areas approximately equivalent to the openings of the third grid 13 and fourth grid 14 that determine the diameter of the electron lens (inside the dotted line in the figure). First, as shown in FIG. 4, the state is equivalent to the state in which the distance between the two cylindrical electrodes is simply increased, without being affected by the surrounding electric field. Therefore, the axial potential distribution becomes quite gentle as shown in FIG. 5, the electro-optical magnification by this electron lens is reduced, and the spherical aberration coefficient is also reduced, so that the lens performance is significantly improved.

Simply increasing the distance between the two electrodes as shown in Figure 4 is not practical because, as mentioned above, the potential distribution will be disturbed by the influence of other electric fields within the network. However, as in the present invention, at least one auxiliary electrode having a diameter considerably larger than the electron lens aperture is disposed between two electrodes, and a potential approximately halfway between the two electrode potentials is applied to this auxiliary electrode. Therefore, it is possible to shield other undesired electric fields within the network and to not disturb the necessary electric field of the electron lens section, so it is possible to simply increase the distance between the two electrodes as shown in Fig. 4. An electronic lens with equivalent high performance can be formed.
At this time, the hole in the auxiliary electrode only needs to be one large hole, and unlike the other electrodes, three electron beam passing holes are not required, so the three holes are each made larger without changing the center distance. Even if this is not possible, the performance of the electron lens can be improved very easily by increasing the distance between the electrodes.

In the color picture tube electron gun of the above embodiment, three electron beams must be converged at one point on the shadow mask or screen (target), and several methods are known for this purpose. That is, there are a method of tilting and arranging the electron guns themselves on both sides, a method of tilting the main lenses or other electron lenses on both sides, and a method of forming an asymmetric lens. Although these conventional methods can be used as they are in the present invention, the convergence can also be achieved by the structure of the auxiliary electrode in the present invention. That is, as shown in FIGS. 7a and 7b, the diameter of the auxiliary electrode in the X direction on the fourth grid side
By making DX4 smaller than the X-direction diameter DX3 on the third grid side, the electron beams on both sides are slightly deflected toward the central electron beam, thereby achieving convergence. This is X-Z
In the axial cross section, the potential of the auxiliary electrode on the fourth grid side penetrates into the electron lens part more than the potential of the auxiliary electrode on the third grid side, and since this potential is lower than the average potential at that position, the electrons on both sides This is because the beams 3a and 3c receive force inward. Alternatively, as shown in FIGS. 8a and 8b, two auxiliary electrodes 16-1 and 16-2 are used, in which an insulator 60 is adhesively fixed to the flange portions 30a and 30b of the auxiliary electrodes,
These auxiliary electrodes have a third grid potential and a fourth grid potential.
The same result can be obtained by applying a potential approximately midway between the potentials of the grid 14, but by making the potential of the auxiliary electrode 16-2 on the fourth grid 14 side slightly lower than the potential of the auxiliary electrode 16-1 on the third grid 13 side. The above convergence can be achieved for a reason. At this time, the electrode lengths of the two auxiliary electrodes may also be appropriately varied and adjusted.

A ceramic plate is suitable as the insulator 60, and a polyimide adhesive with excellent heat resistance and voltage resistance is suitable as the adhesive. Furthermore, the seventh
Figures a and 8a show Y-Z axis cross-sections as in Figure 2, and Figures 7b and 8b show X-Z axis cross-sections, respectively.

In the embodiment described above, the potential of the auxiliary electrode is supplied from the outside through the stem pin, but the present invention is not limited to this, and the potential may be supplied by resistance division. For example, the 9th
As shown in the figure, a resistive material 51 and a connecting portion 52 are arranged on a thin ceramic substrate 50, and a glass coat 5
As shown in FIG. 10, the three resistors 54 are installed behind the insulating supports 2a and 2b that support each electrode of the electron gun 1, and the insulating supports 2 on the fourth grid 14 side are
One side of the resistor 54b installed behind the convergence electrode 15 is connected to apply the anode high voltage Eb, the other side is connected to the auxiliary electrode 26b side, and the resistor 54b is installed behind the insulating support 2a on the third grid 13 side. The resistor 54a installed at do. With this configuration, the electrical configuration will be as shown in Figure 11, and the auxiliary electrode and third grid will be connected to the anode high voltage Eb.
A divided voltage is supplied by the resistor.

As such resistors 54a and 54b, resistors used as a method for supplying the electrode potential of the electrostatic convergence adjustment electrode in color picture tubes are suitable.

In the embodiment shown in FIG. 10, the resistor is in the form of a single plate and is installed behind the insulating support, but the present invention is not limited to this, and the resistive material can be applied directly behind the insulating support. Needless to say, the insulating support itself may be used as a resistor.

As described above, if the auxiliary electrode potential is supplied by resistor division, there is no need to supply a medium-high voltage auxiliary electrode potential at the stem part, and the withstand voltage reliability around the stem part is improved, making it highly practical. We can provide cathode ray tubes. Furthermore, if the third grid potential is also supplied by resistor division, the withstand voltage reliability around the stem part will be further improved, and since the third grid potential can be controlled with a low voltage via the stem pin, it will be possible to dynamically control the electron lens. It becomes easy to adjust the focusing state.

Furthermore, the main lens portion of the above embodiment is basically a bipotential lens consisting of two electrodes, a third grid and a fourth grid, and an auxiliary electrode having a large aperture is arranged between the electrodes. The present invention is not limited to this, but may be based on a unipotential lens as shown in FIG. 12a, or may be based on a quadrapotential lens as shown in FIG. The essence of the present invention does not change even if a periodic potential type lens as shown in c is used as the basis, or other tripotential type lenses are used as the basis. Figures 12a to 12c show schematic configuration diagrams of the main lens part, and the present invention is applied by arranging auxiliary electrodes in all the parts where the electron lens is formed. It goes without saying that the present invention may be applied only to this section. In particular, in the lens systems shown in Figures 12b and 12c, the voltage of the third grid _G3 can be set to about 8 to 9KV, so the quality of the electron beam from the object point formation part can be used in the best condition, and the overall The performance of standard electron guns will be even better.

Further, although the above embodiment has a structure in which three electron guns are integrated in a row in the horizontal direction, the present invention is not limited to this, and the present invention can also be applied to a structure in which three electron guns are arranged in an equilateral triangle shape, and many other structures. It goes without saying that the present invention can be applied to a structure in which multiple electron guns are arranged or a single electron gun structure.

〔Effect of the invention〕

As described above, according to the present invention, one auxiliary electrode larger than these electrodes is arranged between two opposing electrodes, and the auxiliary electrode and the two electrodes are each fixedly held by an insulating support, and this insulating support By using a cathode ray tube electron gun with a structure in which the body is divided into two parts by an auxiliary electrode part, and the two electrodes are fixed via the auxiliary electrode, the aperture diameter of the auxiliary electrode part can be adjusted according to the inner diameter of the neck. It can be made large enough until it is limited. In addition, by applying an intermediate potential between the two opposing electrodes, the distance between the two opposing electrodes can be set sufficiently large, making it practical to create a long focal length lens with a long distance between the electrodes. It can be formed without any problem. The cathode ray tube electron gun of the present invention has a simple structure and is easy to manufacture, making it possible to provide a highly practical and high performance electron gun for cathode ray tubes.

In addition, in the electron gun of the present invention, a high-performance electron gun can be obtained without increasing the beam spacing between multiple electron beams, that is, the distance between the electron beam passing holes, so that it is possible to obtain a high-performance electron gun with less deflection power and high convergence quality in a color picture tube. It can be used as a good high performance electron gun.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and is a side sectional view of an electron gun for a color picture tube, FIGS. 2a and 2b are sectional views along the Y-Z axis and the X-Z axis of FIG. Third
Figure a, Figure 3 b, and Figure 4 are equipotential distribution diagrams for explaining the present invention, and Figure 3 a and Figure 3 b correspond to Figure 2 a and Figure 2 b, respectively. 4 is a sectional view of the coaxial cylindrical lens, FIG. 5 is an axial potential distribution diagram in FIG. 4, FIG. 6 is a perspective view of the electrode used in the embodiment of FIG. 1, and FIG. Figures a, 7b, 8a and 8b show other embodiments of the present invention; Figures 7a and 8a,
Figures 7b and 8b are Y-Z axes and X-axes, respectively.
9 is a sectional view showing a part of the resistor, FIG. 10 is an embodiment of the present invention using the resistor shown in FIG. 9, and FIG. 11 is a cross-sectional view showing a part of the resistor. The electrical configuration diagrams, FIG. 12a, FIG. 12b, and FIG. 12c are side sectional views showing other embodiments of the present invention. 1... Electron gun, 2a, 2b... Insulating support, 3
a, 3b, 3c...Electron beam, 13...Third grid, 14...Fourth grid, 15...Convergence electrode, 16...Auxiliary electrode, 54a, 54
b...Resistor.

Claims (1)

[Claims] 1 An electron gun comprising at least an electron beam generating section and a main lens section for focusing the electron beam onto a predetermined target, the main lens section having at least two opposing electrodes each having an electron beam passing hole, The part is provided with at least one auxiliary electrode located between these electrodes and having an opening larger than the electron beam passing hole of these electrodes, and each of the electrodes is fixedly held by an insulating support. The main lens portion has a structure in which a relatively low potential and a relatively high potential are applied to the two opposing electrodes, and a relatively intermediate potential is applied to the auxiliary electrode. An electron gun for a cathode ray tube, characterized in that the insulating support body is divided into two along the traveling direction of the electron beam with the auxiliary electrode as a border.