JPH04129136A - Cathode-ray tube, television equipment therewith, monitor apparatus therewith and method of compressing electron beam - Google Patents

Abstract

PURPOSE:To obtain a cathode-ray tube and the like which are applicable to a large screen and have good focusing of electron beams by disposing in series a first quadru- pole magnetic field generating unit for compressing electron beams in one direction and a second quadru-pole magnetic field generating unit for compressing the same in the other direction. CONSTITUTION:Beams are compressed in one direction and expanded in a right-angled direction thereto by a first magnetic field generating unit 1 and then inputted to a second magnetic field generating unit 2. Thereupon, the generated quadru-pole magnetic field expands an adjacent portion to the center of the beams compressed by the first magnetic field unit 1 but the compressed portion of the beams is not expanded very much. On the other hand, since the portion expanded by the first magnetic field generating unit 1 is apart from the center of the beams, the portion is greatly compressed in the center direction by receiving a large force. Thus, the cross-section of the beams is compressed and focused by two series-disposed magnetic field generating units 1, 2 in two directions which are right-angled to each other. Accordingly, the strength of the generated quadru-pole magnetic field is easy to be adjusted and the beam focusing is easy to be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to cathode ray tubes used in color televisions, color monitors, etc., and television devices equipped with the same, and particularly to cathode ray tubes and the like suitable for large screens.

[Prior Art] Color cathode ray tubes (color CRTs) are widely used in color televisions and color monitors, and the screens are becoming larger. As the screen becomes larger, the distance for the beam emitted from the electron gun to reach the screen becomes longer, and the diameter of the beam bright spot at the arrival point tends to become larger. Therefore, it is necessary to perform beam control so that the beam bright spot becomes small. A conventional example of beam control is described in Japanese Patent Laid-Open No. 57-40837.

In this conventional technology, a quadrupole magnetic field generator in which a north pole piece and a south pole piece are arranged in an X-shape is installed between an electron gun and a deflection coil, and a beam is generated by the quadrupole magnetic field. The beam is compressed in one direction perpendicular to the direction of movement of the beam, and in this way the distortion of the beam cross section in the periphery of the screen into an elliptical shape is corrected.

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, a quadrupole magnetic field is generated only in one axis direction because the purpose is to eliminate peripheral distortion of the electron beam. However, in cathode ray tubes used for large screens of 3 inches or more, the beam cross section spreads in all directions, unlike the unidirectional distortion of the electron beam at the periphery of the screen. It is not possible to correct the spread.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cathode ray tube that can be used for large screens and has good electron beam convergence.

[Means for solving the problem] In order to achieve the above object, in the present invention, R, G
, B, a first magnetic field generator for generating a quadrupole magnetic field that compresses the beam cross section in a certain direction, and a quadrupole magnetic field that compresses the beam cross section in a direction perpendicular to the above direction. A second magnetic field generating device is installed in series. In addition, the magnetic field generator consists of four conductive wire bundles arranged parallel to the traveling direction of each beam, and each conductive wire bundle is located at each vertex of a rectangle centered on the beam within a cross section perpendicular to the beam traveling direction. The conductor bundles adjacent to each other on the sides of this rectangle are configured to conduct currents of the same magnitude in opposite directions, or each beam has four permanent rods placed parallel to its traveling direction. Each bar magnet, made of a magnet or an electromagnet, is located at each vertex of a rectangle centered on the beam in a cross section perpendicular to the direction of beam travel, and the magnetic poles of adjacent magnets on the sides of this rectangle are arranged in opposite directions. did.

[The acting quadrupole magnetic field generates a Lorentz force on the beam, and within the cross section perpendicular to the beam traveling direction, the conductor flux of the magnetic field generator or the two diagonal directions of the rectangle formed by the bar magnet is 1
It compresses the beam in one direction and expands it in the other, and the Lorentz force increases as it moves away from the beam center and approaches the wire bundle or bar magnet. Therefore, the first
When the beam is compressed in one direction by the magnetic field generator and expanded in a direction perpendicular to that, the beam is input to the magnetic field generator in cylinder 2, and the quadrupole magnetic field generated by this device is the first
The compressed part of the beam is expanded by the magnetic field generator, but this Lorentz force is small because it is close to the center, so the compressed part of the beam is not expanded much. On the other hand, since the portion expanded by the first magnetic field generator is away from the beam center, it receives a large force and is greatly compressed toward the center. In this way, the beam cross section is compressed and focused from two orthogonal directions by the two magnetic field generators installed in series. Also, if these devices are constructed from a bundle of conducting wires or a rod-shaped electromagnet.

It becomes easy to adjust the strength of the quadrupole magnetic field generated by the current flowing through them, and beam convergence can be easily adjusted.

[Example] The present invention will be explained below using examples.

FIG. 1 is a structural diagram of an embodiment of a magnetic field generator which is a feature of the present invention, in which each of the coils 3 and 4 is connected to the magnetic field generator 1.
The magnetic field generators 1 and 2 are arranged in series in the beam direction and each generates a quadrupole magnetic field. and the deflection coil. The shield cup 5 has conventionally been provided near the beam exit of the electron gun and has the function of shielding the leakage magnetic field from the deflection coil. I try to use the space effectively.

Figures 2(a) and 2(b) show the external appearance of the magnetic field generator 1.2, and the parts other than the coils 3.4 are provided with electron beam passage holes 7 as shown in Figure 3. Insulating housing 8
It is a combination of a and 8b. The casings 8a and 8b are formed by press-molding a non-magnetic material, and are coated with an insulating coating. The coil 3.4 is formed by winding many layers of conductive wire on this coating, and Figure 4 shows only one turn of the conductive wire of each coil 3.4. Explain.

In FIG. 4, each coil is shown as a single wire as described above, but in reality this is a bundle of conductors.

However, since this conductor bundle is bundled together, there is no difference in principle even if it is just a single wire. Magnetic lines of force H1 to H8, etc., generated when a current flows through the coil 3.4 in the direction of the arrow shown, are shown in circles with arrows along with their directions. However, H
1 to H8 are the symbols given only to the parts surrounding the beam R, and the symbols for other lines of magnetic force are omitted. Also, all of the magnetic lines of force shown here are generated from the part of the coil parallel to the beam, but since a current perpendicular to the beam does not produce any force on the convergence or expansion of the beam, only the lines of magnetic force shown are generated. It's enough to think about it.

Now, if we look at the coil current and magnetic field lines in Figure 4 in a cross section perpendicular to the beam, we get Figure 5 (a) for coil 3 and Figure 5 (b) for coil 4. In this figure, each beam R,G,
Assuming that B goes perpendicularly from the back to the front of the drawing, the beam R is generated by the coil 3 of the magnetic field generator 1 as shown in Fig. 4(a).
receives the Lorentz force in the direction of the arrow, and also receives the magnetic field generator 2
The coil 4 receives a Lorentz force in the direction of the arrow in FIG. 4(b). Beam B also experiences a Lorentz force in exactly the same direction as beam R, but with respect to beam G.

The coils surrounding it are shared by beams R and H on both sides, and the direction of the current is exactly opposite, so the Lorentz force is also opposite to that for beams R and H. Therefore, as each beam passes through the two coils 3.4, it is alternately subjected to compression and expansion forces from different directions, but the central axis of the quadrupole magnetic field (beam center) has a weak magnetic field strength and is eccentric. The magnetic field strength is stronger. Therefore, the outer edge of the beam, which is biased towards the center after being subjected to a compressive force by the coil 3, is not subjected to a large expansion force by the coil 4. Further, the outer edge of the beam which is eccentric due to the stretching force applied by the coil 3 is subjected to a large compressive force by the coil 4. Therefore, each beam as a whole converges in all directions. In addition, the magnitude of the current that generates the magnetic lines of force H1 to H4, etc. is all the same and is the current of coil 3 multiplied by the number of turns (same for coil 4), so it is easy to adjust the convergence force by changing the coil current. can be done.

FIGS. 6 and 7 are structural diagrams showing another embodiment of the magnetic field generating device which is a feature of the present invention, in which eight bar magnets 11 are made of a non-magnetic material as shown in FIG. It is installed in a recess of the housing 10, so that adjacent magnetic fields are opposite to each other. The entire structure is installed in the same shield cup 5 as shown in FIG. 1, and the space near the electron gun entrance is effectively utilized.

In the case of this embodiment, eight magnetic poles on the beam entrance side generate a quadrupole magnetic field around the beam as shown in FIG. side 8
The magnetic poles form a second magnetic field generator as shown in FIG. 8(b). Here, the lines of magnetic force are indicated by thin arrows, and when each beam passes perpendicularly from the back to the front of the drawing, the Lorentz force indicated by the thick arrows acts on each beam. This is simply the direction of the force in FIG. 5 rotated 45 degrees to the left, and beam convergence can be achieved using exactly the same principle.

In this embodiment, a permanent magnet is used as the bar magnet, but in this case, power supply to the magnet and a device for it are unnecessary. Further, if the bar magnet is an electromagnet, the magnetic field strength can be easily adjusted as in the embodiment shown in FIG.

[Effects of the Invention] According to the present invention, two
Since two quadrupole magnetic fields are formed, the beam receives compressive force from two directions toward the central axis and is sufficiently focused.Furthermore, a bar-shaped permanent magnet is used to generate a quadrupole magnetic field. This eliminates the need for power supply, and if a quadrupole magnetic field is generated using a rod-shaped electromagnet or coil, the convergence force can be freely controlled by adjusting the supplied current.

[Brief explanation of drawings]

1, 2, and 3 are structural diagrams of an embodiment of a magnetic field generating device that is a feature of the present invention, FIGS. 4 and 5 are operation explanatory diagrams of the embodiment of FIG. 1, and FIG. 6 and FIG. 7 are structural diagrams of another embodiment of the magnetic field generating device which is a feature of the present invention, and FIG.
FIG. 3 is an explanatory diagram of the operation of the embodiment shown in the figure. 1.2... Magnetic field generator, 3, 4... Coil, 5...
・Shield cup, 11... Bar magnet. Agent Patent Attorney Tadashi Akimoto Actual figure figure figure figure figure figure figure figure (α) figure figure (b) figure B AR figure figure figure (G) figure (b)

Claims (1)

[Claims] 1. In an electron beam compression method for compressing the beam diameter of an electron beam, a plurality of quadrupole magnetic fields with different polarities are arranged in series, an electron beam is passed through the center of each quadrupole magnetic field, An electron beam compression method characterized by compressing an electron beam in one direction with one quadrupole magnetic field and compressing the electron beam in another direction with another quadrupole magnetic field. 2. An electron beam compression device that compresses the beam diameter of an electron beam, which includes a first quadrupole magnetic field generator that compresses the electron beam in one direction, and a second quadrupole magnetic field generator that compresses the electron beam in another direction. An electron beam compression device comprising: a polar magnetic field generator. 3. In an electron beam compression method that compresses the beam diameters of three electron beams corresponding to RGB, multiple quadrupole magnetic fields with different polarities are arranged in series for each electron beam, and the center of each quadrupole magnetic field is An electron beam compression method characterized by passing each electron beam through a quadrupole magnetic field, compressing the electron beam in one direction with a quadrupole magnetic field, and compressing the electron beam in another direction with the next quadrupole magnetic field. . 4. In an electron beam compression device that compresses the beam diameters of three electron beams corresponding to RGB, a first quadrupole magnetic field generator that compresses the electron beam in a certain direction for each electron beam; An electron beam compression device comprising: a second quadrupole magnetic field generator that compresses an electron beam in a different direction. 5. In a cathode ray tube equipped with an electron gun and a deflection coil,
A first magnetic field generator that generates a quadrupole magnetic field to compress an electron beam in a certain direction, and compresses the electron beam compressed by the first magnetic field generator in a direction different from the compression direction. A cathode ray tube characterized in that a second magnetic field generator for generating a quadrupole magnetic field is provided between the electron gun and the deflection coil. 6. In a cathode ray tube equipped with an electron gun and a deflection coil,
a first magnetic field generator that generates a quadrupole magnetic field to compress electron beams corresponding to each color in a certain direction; and a first magnetic field generator that generates a quadrupole magnetic field to compress electron beams corresponding to each color in a certain direction; A second quadrupole magnetic field that generates a compressive quadrupole magnetic field in a direction different from that of
A cathode ray tube, characterized in that a magnetic field generator is provided between the electron gun and the deflection coil. 7. A monitor device comprising a cathode ray tube, comprising the cathode ray tube according to claim 5 or 6 as the cathode ray tube. 8. A television device comprising a cathode ray tube, the television device comprising the cathode ray tube according to claim 5 or 6 as the cathode ray tube.