JPH08115684A - Electron gun - Google Patents

Abstract

PURPOSE: To provide an electron gun which can enhance SVM sensitivity without strengthening the magnetic field of an SVM coil. CONSTITUTION: A G3 electrode 1, a G4 electrode 2, a G5 electrode 13, and a G6 electrode 4 are placed in sequence from time downstream side, and the G5 electrode 13 is divided into a downstream G5 electrode 131 and an upstream G5 electrode 132 in such a way that a clearance of about 3 to 5mm is provided in a portion immediately below an SVM coil 6. An electron gun can thus be obtained whose SVM sensitivity is enhanced without the need for strengthening the magnetic field of the SVM coil in order to compensate decrease in SVM sensitivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun used in a television receiver, and more particularly to an SVM (scanning speed modulation: SCANNI).
NG VELOCITY MODULATION) Electron gun capable of improving sensitivity.

[0002]

2. Description of the Related Art FIG. 7 shows the structure of a television receiver. Figure 7
In FIG. 1, a CRT (cathode ray tube) 10 is composed of a screen portion 101 on which an electron beam is irradiated and a neck portion 102 on which an electron gun 8 for generating an electron beam is arranged, and a deflection is made from the neck portion 102 to the screen portion 101. It has a yoke 9. Further, an SVM coil (scanning speed modulation coil) 6 is arranged at a position of the neck portion 102 where the electron gun 8 is arranged.

FIG. 8 shows a partial structure of the electron gun 8. Here, an in-line type electron gun will be described as an example of the electron gun 8. FIG. 8 shows an electrode system (electron beam focusing system) for focusing the electron beam in the electron gun 8. The electrode system is fixed by being sandwiched between two bead glasses 5 arranged in parallel, and when called the upstream side and the downstream side along the flow of the electron beam, the G3 electrode 1, the G4 electrode 2, and the G4 electrode are sequentially arranged from the downstream side.
Grid electrodes called 5 electrodes 3 and G6 electrodes 4 are arranged.

The G3 electrode 1 and the G4 electrode 2 are electrodes having an extremely short axial length, and the G5 electrode 3 is a downstream side G electrode.
The five electrodes 31 and the upstream G5 electrode 32 are connected to each other without any gap, forming a substantially cylindrical electrode having an extremely long axial length. The G6 electrode 4 has an axial length. However, the electrodes are longer than the G3 electrode 1 and the G4 electrode 2, and each has a structure in which a cap having a brim is used alone or a cap having a brim is combined. In such an electrode, the G3 electrode 1 and the G5 electrode 3 are 7-9.
The G4 electrode 2 is supplied with a potential of 200 to 400 V, and the G6 electrode 4 is supplied with a voltage of about 30 KV. The electron beam is focused by such potential distribution. Here, as indicated by the broken line in FIG. 8, the S is provided outside the neck portion 102 around the G5 electrode 3.
The VM coil 6 is arranged.

FIG. 9 shows a view taken along the line A-B 'of FIG. In FIG. 9, a G5 electrode 3 having a substantially oval outline shape is provided between two bead glasses 5 arranged in parallel vertically.
Are arranged with their longitudinal direction horizontal. The G5 electrode 3 is provided with a protruding portion (referred to as a rising portion) P which is inserted into the bead glass 5 and is connected to the bead glass 5 on each of two long sides of the flange portion. In FIG. 9, the structure of the G5 electrode 3 is shown to have three independent circular holes in order to pass three electron beams independently, but the three electron beams are grouped together. In some cases, it has a shape having an elliptical hole for the passage.

Next, the operation of the SVM coil 6 will be described. The SVM coil 6 is a coil for adding an SVM function (scanning speed modulation function) to the television receiver. SVM
The function is an electric circuit function that makes the image clear and improves the sharpness of the screen by increasing or decreasing the horizontal scanning speed of the horizontal deflection magnetic field according to the brightness of the video signal.

The structure of the SVM coil 6 is shown in FIG. S
The VM coil 6 is a coil formed by arranging two coils whose contours are in the shape of a horse saddle so that the inner sides of the saddle face each other. The current path of the SVM coil 6 is shown by an arrow in FIG. As shown in FIG. 11, the two coils constituting the SVM coil 6 are connected in series, and when energized, as indicated by the arrow in FIG. 10, from one crest of the saddle to the crest of the other saddle. Generate a magnetic field directed at.

According to the change amount of the brightness of the video signal, the SV
When the current flowing through the M coil 6 is changed, the SVM coil 6
Similarly, the magnetic field generated in the horizontal direction changes, and the change in the magnetic field changes the horizontal scanning speed of the horizontal deflection magnetic field of the television receiver.

Here, the G5 electrode 3 of the conventional electron gun 8 is a substantially cylindrical electrode having an extremely long axial length, and is an SV.
In many cases, the cylinder portion is located below the M coil 6,
The magnetic field generated by the SVM coil 6 arranged around the G5 electrode 3 was supposed to pass through the G5 electrode 3 and change the electron beam.

[0010]

As described above, in the conventional electron gun 8 of the television receiver, the tubular portion of the G5 electrode 3 is often located below the SVM coil 6,
Since the magnetic field of the SVM coil 6 was shielded by the tubular portion of the G5 electrode 3 and an eddy current was generated on the metal surface that shields the electric field of the G5 electrode 3, the influence of the magnetic field of the SVM coil 6 on the electron beam was weakened. . However, since the position where the SVM coil 6 is provided has already been determined by design,
The SVM coil 6 cannot be moved. Therefore, S
In order to increase the sensitivity of the VM function, it is necessary to increase the number of turns of the SVM coil 6 or increase the amount of current to strengthen the magnetic field of the SVM coil.
Alternatively, there is a problem that it leads to an increase in power consumption.

The present invention has been made to solve the above problems, and an object thereof is to obtain an electron gun capable of improving the SVM sensitivity without increasing the magnetic field of the SVM coil.

[0012]

According to a first aspect of the present invention, there is provided an electron gun for modulating an electron beam focusing system and an electron beam scanning speed arranged around the electron beam focusing system. An electron gun including a scanning velocity modulation coil is characterized in that the electron beam focusing system is provided with an electrode having a divided gap in a region surrounded by the scanning velocity modulation coil.

According to a second aspect of the present invention, in the electron gun according to the first aspect, the magnetic field formed by the scanning velocity modulation coil can pass through the gap without being blocked, and the electron It has a gap width that can prevent penetration of an electric field from the outside of the beam focusing system.

An electron gun according to a third aspect of the present invention is the electron gun according to the second aspect, wherein a plurality of conductor plates having through holes for the electron beam are provided at end portions of the electrodes forming the gap. A shield electrode that shields the electric field from the outside of the electron beam focusing system is further formed so as to generate an eddy current even when the conductor plate receives a magnetic field formed by the scanning velocity modulation coil. It has a thickness that can be suppressed.

An electron gun according to a fourth aspect of the present invention is the electron gun according to any one of the first to third aspects,
The electrode is configured such that the center line of the scanning velocity modulation coil in the width direction and the center line of the gap in the gap width direction coincide with each other.

[0016]

According to the electron gun of the present invention as defined in claim 1,
Since the electron beam focusing system is provided with the divided electrode having a gap in the area surrounded by the scanning velocity modulation coil, the magnetic field formed by the scanning velocity modulation coil is blocked by the electrode, and the eddy current generated in the electrode is generated. By this, weakening is prevented and the action on the electron beam is prevented from being lowered.

According to the electron gun of the second aspect of the present invention, the magnetic field formed by the scanning velocity modulation coil can pass through the gap without being blocked, and the electric field permeates from the outside of the electron beam focusing system. Since it is configured to have a gap width capable of preventing the above, it is possible to prevent the action of the magnetic field formed by the scanning velocity modulation coil on the electron beam from being lowered, and to prevent the electric field from the outside of the electron beam focusing system from occurring. Penetrating and affecting the trajectory of the electron beam are prevented.

According to the electron gun of the third aspect of the present invention, the electron beam focusing system is formed by stacking a plurality of conductor plates having electron beam passage holes at the ends of the electrodes forming the gap. By further including a shield electrode that shields an electric field from the outside of the device, it is possible to further prevent the electric field from penetrating the gap from the outside of the electron beam focusing system. Further, since the shield electrode is formed of the conductor plate having a thickness capable of suppressing the generation of the eddy current even when receiving the magnetic field formed by the scanning velocity modulation coil, the shield electrode does not weaken the magnetic field.

According to the electron gun of the fourth aspect of the present invention, the electrodes are configured such that the center line of the scanning velocity modulation coil in the width direction and the center line of the gap in the gap width direction coincide with each other. Therefore, the magnetic field that becomes the strongest in the central portion in the width direction of the scanning velocity modulation coil is reliably applied to the gap.

[0020]

【Example】

<First Embodiment> A first embodiment of the electron gun according to the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 shows a partial configuration of the electron gun 18 according to the first embodiment. Here, an in-line type electron gun will be described as an example of the electron gun 18. The same components as those of the conventional electron gun described with reference to FIGS. 7 and 8 are designated by the same reference numerals, and redundant description will be omitted.

FIG. 1 shows an electrode system of the electron gun 18 for focusing an electron beam. In FIG. 1, G3 electrode 1, G4 electrode 2, G5 electrode 13, G6 are arranged in this order from the downstream side.
The configuration in which the electrodes 4 are arranged is the same as that of the conventional electron gun described with reference to FIG. 8, but the conventional G5 electrode 3 is roughly classified into a downstream G5 electrode 31 and an upstream G5 electrode 32. Two
The two electrodes were connected without any gap, and the length in the axial direction was extremely long.
Is 3 to 5 m in a portion located directly below the SVM coil 6.
Downstream G5 electrode 131 so that a gap of about m is provided
And the upstream G5 electrode 132 is divided.

In FIG. 1, the downstream G5 electrode 131 has two
It is shaped like a brim and a brim of a hat with two brims. For convenience, the downstream side is called an electrode 131A and the upstream side is called an electrode 131B. The upstream G5 electrode 132 has a shape in which a hat having two flanges is in contact with the flange of one of the hats, the head of which faces the downstream side, and the head of the other hat. For convenience, the downstream side is referred to as an electrode 132A and the upstream side is referred to as an electrode 132B. It should be noted that the electrode 132B has a shape in which the head also has a collar as in the case of the G6 electrode 4, but the side of the electrode 132A in contact with the collar is the head. Since the total length of the G5 electrode 13 cannot be changed by design, the length of the gap is determined according to the length of the electrodes 131B and 132A.

Both the downstream G5 electrode 131 and the upstream G5 electrode 132 are connected by a conductive ribbon 7 for keeping the same potential. FIG. 2 shows a view taken along arrow A-B 'of FIG. In FIG. 2, the outline shape of the downstream side G5 electrode 131 is almost the same as that of the conventional G5 electrode 3 described with reference to FIG. 9, and thus a duplicate description will be omitted, but a conductive ribbon connection tab for connecting the conductive ribbon 7 is omitted. 71 is the downstream side G5
The electrode 131 is provided on one long side of the flange portion of the electrode 131. The conductive ribbon connection tab 71 is provided at a position where it does not contact the bead glass 5, and the conductive ribbon 7 is welded thereto.
The conductive ribbon connection tab 71 is connected to the upstream G5 electrode 132.
, And both are connected by a conductive ribbon 7.

As described above, the G5 electrode 13 has the S
The magnetic field of the SVM coil 6 is divided into a downstream G5 electrode 131 and an upstream G5 electrode 132 so that a gap of about 3 to 5 mm is provided directly below the VM coil 6. Is blocked by the G5 electrode 13,
The generation of eddy currents on the surface of the cylinder of the five-electrode 13 is prevented. Therefore, the magnetic field of the SVM coil 6 directly acts on the electron beam, and the SVM sensitivity can be improved.

The gap width may be equal to or smaller than the width of the SVM coil 6, but if it is too wide, the external electric field cannot be shielded and the electron beam is affected.
The M sensitivity cannot be improved. Gap width of 3-5m
About m is based on experience, and this value is S
Depending on the width of the VM coil 6 and the total length of the G5 electrode 13, the width of the SVM coil 6 is 25 mm in the present embodiment.
This is a value obtained when the total length of the G5 electrode 13 is 20 mm.

<Second Embodiment> A second embodiment of the electron gun according to the present invention will be described below with reference to FIGS. FIG. 3 shows a partial configuration of the electron gun 28 according to the second embodiment. Here, an in-line type electron gun will be described as an example of the electron gun 18. The same components as those of the conventional electron gun described with reference to FIGS. 7 and 8 and the first embodiment described with reference to FIG. 1 are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 3 shows an electrode system for focusing the electron beam in the electron gun 28. In FIG. 3, G3 electrode 1, G4 electrode 2, G5 electrode 13, and G6 are arranged in this order from the downstream side.
The configuration in which the electrode 4 is arranged is the same as that of the conventional electron gun described with reference to FIG. 8, and the G5 electrode 13 has a downstream side G so that a gap is provided in a portion located directly below the SVM coil 6.
5 electrodes 131 and an upstream G5 electrode 132, but the thin metal plate 11 having a thickness of about 0.2 to 0.5 mm is provided on the heads of the electrodes 131B and 132A.
A plurality of shield electrodes 11 are attached.

As described in the first embodiment with reference to FIG. 1, when a gap is provided in the portion of the G5 electrode 13 located directly below the SVM coil 6, the SVM coil 6 does not need to have a strong magnetic field and the SVM coil 6 does not need to be strong. Sensitivity can be improved, but neck 102
There is a risk that an electric field is generated by the positive charges accumulated on the inner wall of the Pt, and the electric field penetrates into the gap and disturbs the convergence of the electron beam depending on the length of the gap width. In the first embodiment, the gap length is set to 3 to 5 based on experience.
However, it is impossible to completely shield the electric field on the inner wall of the neck. Particularly, in a large electron gun having a short distance to the inner wall of the neck, the electric field on the inner wall of the neck greatly affects the convergence of the electron beam.

Therefore, by providing the shield electrode 11 in which thin metal plates 111 having a thickness of about 0.2 to 0.5 mm are adhered to each other in the gap portion, the gap length is shortened according to the thickness of the shield electrode 11. Since an eddy current is unlikely to occur on the surface of the shield electrode 11, a pseudo gap is maintained for the magnetic field of the SVM coil 6, so that the SVM sensitivity can be improved and the shield effect can be enhanced.

In terms of performance, it is also possible to form the shield electrode 11 using a total of 4 to 6 metal plates 111 having a thickness of 0.2 to 0.5 mm for a gap length of 3 to 5 mm. It is empirically known that it is also effective in terms of aspects.

4 and 5 are plan views of the metal plate 111 constituting the shield electrode 11. FIG. 4 shows a metal plate 111A provided with three independent circular holes for passing three electron beams independently, and FIG.
There is shown a metal plate 111B provided with elliptical holes for passing the electron beams of the book as a whole. In each case, the contour shape is an elliptical shape and is used in conformity with the shapes of the G3 electrode 1 to the G6 electrode 4.

The material of the metal plate 111 is the G5 electrode 13
It is preferable that the same material as that of the G5 electrode 13 is used as long as the eddy current can be reduced.
The conductor need not be metal.

<Modification 1> In the first and second embodiments described with reference to FIGS. 1 and 3, the relative position of the gap with respect to the SVM coil 6 is not mentioned.
Since the center of the VM coil 6 has the highest magnetic flux density of the magnetic field, by making the center of the SVM coil 6 coincide with the center of the gap provided in the G5 electrode 13, the SVM sensitivity can be improved efficiently. FIG. 6 shows a configuration in which the center of the SVM coil 6 and the center of the gap provided in the G5 electrode 13 are aligned. Since the position of the SVM coil 6 cannot be moved,
The centers of the electrodes 131B and 132A are changed by changing the lengths thereof.

<Modification 2> In the first and second embodiments described with reference to FIGS. 1 and 3, an in-line type electron gun in which three electron beams are arranged in one horizontal row has been described as an example. However, the present invention is also applicable to a delta type electron gun in which three electron beams are arranged so as to draw a triangle.

[0035]

According to the electron gun of the first aspect of the present invention, the magnetic field formed by the scanning velocity modulation coil is prevented from being blocked by the electrodes and weakened by the eddy current generated in the electrodes. Since the reduction of the effect on the electron beam is prevented, it is possible to obtain the electron gun which does not need to strengthen the magnetic field formed by the scanning velocity modulation coil in order to compensate for the reduction of the scanning velocity modulation sensitivity.

According to the electron gun of the second aspect of the present invention, the action of the magnetic field formed by the scanning velocity modulation coil on the electron beam can be prevented from being lowered, and the electron beam focusing system can be used from outside. Of the electron beam is prevented from penetrating and affecting the orbit of the electron beam, so that the sensitivity of the scanning velocity modulation is prevented from decreasing, and the convergence of the electron beam is deviated by the influence of the electric field from the outside of the electron beam focusing system. An electron gun that prevents

According to the electron gun of the third aspect of the present invention, by providing the shield electrode at the end of the electrode forming the gap, the electric field can further penetrate into the gap from the outside of the electron beam focusing system. To be prevented. Further, since the shield electrode does not weaken the magnetic field, an electron gun can be obtained in which the effect of preventing the reduction of the scanning speed modulation sensitivity is not deteriorated.

According to the electron gun of the fourth aspect of the present invention, the magnetic field that becomes the strongest in the central portion of the scanning velocity modulation coil in the width direction is reliably applied to the gap.
It is possible to obtain an electron gun that efficiently prevents a reduction in scanning speed modulation sensitivity.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of an electron gun according to the present invention.

FIG. 2 is a plan view showing the configuration of the first embodiment of the electron gun according to the present invention.

FIG. 3 is a configuration diagram showing a second embodiment of the electron gun according to the present invention.

FIG. 4 is a plan view showing a configuration of a metal plate of a second embodiment of the electron gun according to the present invention.

FIG. 5 is a plan view showing a configuration of a metal plate of a second embodiment of the electron gun according to the present invention.

FIG. 6 is a configuration diagram showing a modification of the first and second embodiments of the electron gun according to the present invention.

FIG. 7 is a diagram showing a configuration of a television receiver.

FIG. 8 is a configuration diagram showing a conventional electron gun.

FIG. 9 is a plan view showing the configuration of a conventional electron gun.

FIG. 10 is a perspective view showing a configuration of an SVM coil.

FIG. 11 is a perspective view showing a current flow of the SVM coil.

[Explanation of symbols]

6 SVM coil, 7 conductive ribbon, 13 G5 electrode,
131 downstream G5 electrode, 132 upstream G5 electrode, 1
31A, 131B, 132A, 132B electrodes, 71
Conductive ribbon connection tab, 11 shield electrode, 111, 1
11A, 111B metal plate.

Claims (4)

[Claims] 1. An electron gun including an electron beam focusing system and a scanning velocity modulation coil arranged around the electron beam focusing system for modulating a scanning velocity of the electron beam. Is an electron gun, comprising electrodes divided and having a gap in a region surrounded by the scanning velocity modulation coil. 2. The gap has a gap width that allows a magnetic field formed by the scanning velocity modulation coil to pass therethrough without being interrupted and prevents penetration of an electric field from the outside of the electron beam focusing system. The electron gun according to claim 1. 3. An end portion of the electrode forming the gap,
The electron beam focusing system further comprises a shield electrode formed by stacking a plurality of conductor plates having electron beam passage holes to shield the electric field from the outside of the electron beam focusing system, wherein the conductor plate is the scanning velocity modulation coil. The electron gun according to claim 2, wherein the electron gun has a thickness capable of suppressing generation of an eddy current even when receiving a magnetic field formed by. 4. The electrode is configured such that a center line in the width direction of the scanning velocity modulation coil and a center line in the gap width direction of the gap coincide with each other. The electron gun according to any one of 1.