JPH01169853A - Convergence device - Google Patents

Abstract

PURPOSE:To improve the focus performance by optionally selecting the set angle of core projections and the number of coil turns to make the generated two-pole magnetic field nearly the uniform magnetic field. CONSTITUTION:In a core protruded with eight rectangular projections 1 and 2 in all to the inside on a ring-shaped section at the uniform angle of theta=45 deg., coils 3 and 4 (5 and 6) are wound on the projections to generate the two-pile magnetic field 7 (8) so that one magnetic pole is formed with three core projections: a core projection 1 on the horizontal axis or the vertical axis and the core projections 2 on both sides of it. The number of coil turns of the core projections 2 arranged at the distance of the uniform angle on both sides of the core projection 1 is increased as it approaches the axis, thus the magnetic flux density on the periphery is increased, and the whole electrode is operated as an auxiliary electrode generating nearly the uniform magnetic field. The focus performance can be thereby improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a convergence device attached to a cathode tube of an electron gun, and particularly to a convergence device with suitable focusing performance.

[Conventional technology]

In dose-type color televisions and power 2-displays, -
Using a plurality of cathode ray tubes of an electron gun, each monochromatic 11JI cathode ray tube image is projected onto a projection screen via an optical system such as a mirror or a V lens, thereby forming a color screen. At this time, if the image displayed on the projection screen is not corrected in any way, the deflection yaw of the uniform-calm field method is used.
Because the image is projected through an optical system, pincushion distortion and keystone distortion appear.

In order to correct this distortion, a four-pole convergence device was installed at the rear of the deflection yoke on the electron gun side to generate 200 million magnetic fields in the horizontal and vertical directions. The core shape of this device consists of a ring-shaped part and four rectangular core protrusions that protrude inward at the upper, lower, left, and right shelf positions, and a coil wound around each protrusion receives correction synchronized with the deflection current from an external circuit. pass a current,
A 200 million magnetic field was generated between the two protrusions on the horizontal or vertical axis to apply horizontal and vertical deflection forces to the electron beam to correct the distortion.

Further, as in the example described in Japanese Utility Model Publication No. 58-32378, the first core protrusions on the horizontal and vertical axes and four second core protrusions are provided at intermediate angular positions between the first core protrusions. established,
A circuit different from the external circuit is connected to an auxiliary coil wound around the second core projection so as to dynamically correct the coil wound around the first core projection and generate a horizontal or vertical magnetic field. There is an example of a configuration in which static correction is performed by flowing a direct current.

[Problem that the invention seeks to solve]

In the above conventional technology, the core shape for dynamic convergence correction has core protrusions t opposed on the horizontal and vertical axes.
-One set is used. Therefore, as shown in FIG. 6, the magnetic field generated between the two core protrusions 25 is a barrel-shaped magnetic field 26. Figure 7 shows the axial magnetic field strength 1Bo28 and non-uniform magnetic field components B and 29 of the conventional convergence yoke 31.
This is a graph. At this time, the velocity density By on the mirror symmetry axis (X-axis) of the horizontal deflection magnetic field is expressed by the following equation.

BP"Bo 1 B, x" (gauss) In the above equation, higher-order components of the fourth order or higher are omitted. The horizontal axis represents the tube axis direction coordinate 2, and the positive region of the vertical axis B is the pink hook 1 magnetic field component, and the negative region is the barrel magnetic field component. As shown,
The barrel tendency is strongest in the core, resulting in a barrel magnetic field distribution in the entire region9, which distorts the electron beam spot shape and causes deterioration of the orcus performance.

SUMMARY OF THE INVENTION An object of the present invention is to provide a convergence device that improves focusing performance by making the magnetic field generated by the convergence device a substantially uniform magnetic field.

[Means for solving problems]

The above object is to configure one magnetic pole that generates a bipolar magnetic field with one core protrusion located on the axis of symmetry, and two or more core protrusions arranged on both sides at symmetrical angles to the axis of symmetry, Based on the number of turns of the coil on the core protrusion located on the axis, the turn ratio of the coil wound around each core protrusion is set so that the core protrusion near the axis of symmetry is thicker, and the ratio is corrected from an external circuit. This is achieved by passing an electric current to generate a substantially uniform bipolar magnetic field (or a desired bipolar approximate field).

Another method is to configure one magnetic pole that generates a bipolar magnetic field with two or more core protrusions, and wind a coil with the same number of turns around the core protrusions arranged at symmetrical angles to the magnetic field symmetry axis.
Angle t of the core protrusion with respect to the axis of symmetry - 20 degrees or more 45
The above object can be achieved by setting the magnetic field within a range of 100°C or less to generate a substantially uniform bipolar magnetic field (or a desired bipolar magnetic field).

[Effect]

When one magnetic pole is composed of an odd number of five or more core protrusions, a single core protrusion placed on the axis will generate a barrel magnetic field, but if the core protrusions are placed on both sides of this core protrusion at equal angular intervals, a barrel magnetic field will be generated. By winding the core protrusion so that the number of coil turns on the core protrusion increases as the core protrusion approaches the axis, the magnetic velocity density in the peripheral portion is increased, and the entire pole acts as an auxiliary pole that generates a substantially uniform magnetic field.

Next, when it is composed of an even number of core protrusions of 2 or more,
The core protrusions with the same number of coil turns are arranged at equal angles on both sides with the horizontal (or vertical) center at the center, and are divided into two parts, and the arrangement angle with respect to the axis is 20 to 45 degrees depending on the number and shape of the core protrusions. Since it is set within the range of , each core protrusion acts so as to generate a substantially uniform magnetic field for the entire pole.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a first embodiment of the convergence device of the present invention. A ring-shaped part has rectangular protrusions 1 and 2, and a total of 8 protrusions protrude inward at equal angles of θ - 45 degrees.The core has a core protrusion 1t on the horizontal or vertical axis, and the core protrusions on both sides thereof. Coils 3 and 4 (5 and 6) are attached to each protrusion so that 3 pieces together with 2 form one mother seed.
t-winding to generate a dipole magnetic field 7 (8) as shown.

FIG. 3 is an overall view of the convergence device shown in FIG. 1 attached to a cathode ray tube. The convergence device is attached to the rear part of the deflection yoke 31 on the electron gun side, and a correction current (CY current) synchronized with the deflection current is caused to flow from the convergence circuit 23 to the coil 5°4 (5, 6) to reduce the above-mentioned two-pole magnetic field. 7 (8) to deflect the electron beam 10 horizontally (vertically) to correct pincushion distortion and keystone distortion.

FIG. 2 is a diagram showing the results of measuring the axial magnetic field distribution of the convergence device shown in FIG. 1. 5 curves 11-15
The number of turns is 60 turns around the protrusion 1 on the shaft, 80 turns around the protrusions 2 on both sides, and 60 turns.

It shows the non-uniform magnetic field component (Bz/B1) max) when set to 42 turns, 20 turns, and 0 turns, respectively. The horizontal axis 2 shows the distance in the tube axis direction (unit: mm)
9. In the figure, the right side is the electron gun side, and the left side is the deflection yoke side. When the value of the curve is in the upper half of the horizontal axis, the fourth
As shown in the figure, this means that the magnetic velocity density at both positions B on the horizontal axis is larger than the center A of the tube axis A, which is shaped like a pink tube. When the value is in the lower half of the horizontal axis, it means that the barrel magnetic field is larger than the a-flux density at both positions B on the horizontal axis when the rt mouth < barrel-shaped tube axis center point shown in Fig. 5 is taken. do. Curve 15 corresponds to the conventional example in which a 2@magnetic field is generated only by the core protrusion 1 on the shaft, and a strong barrel magnetic field is generated over the entire region in the tube axis direction. In comparison, curve 13 shows the case where approximately 1/F turns = 42 turns are wound around the core protrusions on both sides 45 degrees apart from the protrusion on the axis, and the barrel magnetic field is weak on the electron gun side and the deflection yoke side, and the center There is a weak binkushion magnetic field in some parts, and the overall magnetic field is almost uniform. Other curves 11.12゜1
4, the hollow curve 13 is a condition for forming a substantially uniform magnetic field at the core protrusion position of 45 degrees. In this embodiment, among the five core protrusions constituting one magnetic pole, the core protrusions on both sides are commonly used for the horizontal magnetic field coil 4 and the vertical magnetic field coil 6t. By applying the embodiment shown in FIG. 1, the dipole magnetic field acting on the electron beam 10 can be improved from a conventional barrel magnetic field of 7°8t-1 to a substantially uniform box field. FIG. 9 is a diagram showing how the beam spot is distorted by the barrel magnetic field, and the left side deflection is omitted. When the electron beam is deflected from the 10th position to the 35th position, it is affected by the gradient component of the magnetic field and becomes a vertically distorted elliptical shape as shown in the figure, which causes deterioration in focusing performance.

Therefore, by making the barrel magnetic field into a substantially uniform magnetic field in the embodiment, the influence of the gradient component of the magnetic field can be reduced, and the focusing performance can be improved.

FIG. 8 is a sectional view showing the second embodiment.

One out #! , is composed of two core protrusions 1 (50), coils 5 (5) are wound with the same number of turns, and are arranged left and right at equal angles with respect to the vertical (horizontal) axis. Adjust the angle θ between these two core protrusions from 20 degrees to 4 degrees depending on the width and thickness of the protrusions.
By setting the magnetic field in the range of 5, the generated bipolar magnetic field can be made into a substantially uniform magnetic field, and the same effect as in the first embodiment can be obtained.

In both the first and second embodiments, the case where a substantially uniform magnetic field is generated has been described, but if a bipolar magnetic field with a binction magnetic field or a barrel magnetic field tendency is required under certain usage conditions, the setting angle of the core protrusion may be changed. It is clear that this can be addressed by changing the number of turns of the coil. Further, in the embodiment, both the horizontal general field and the vertical a-field are approximately uniform magnetic fields, but the present invention may be applied to only one of them, and the conventional method may be applied to the other.

〔Effect of the invention〕

By arbitrarily selecting the setting angle of the core protrusion and the number of turns of the coil to be wound, the generated bipolar magnetic field can be made into an approximately equal magnetic field, so the distortion f of the electron beam spot diameter due to the convergence device can be reduced, and the It has the effect of improving orcus performance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the first embodiment of the present invention, FIG. 2 is an axial magnetic field distribution diagram of the embodiment of FIG. 1, and FIG. 5 is an overall layout diagram of the embodiment of FIG. 1. Fig. 4 is an explanatory diagram of the binction magnetic field, Fig. 5 is an explanatory diagram of the barrel magnetic field, Fig. 6 is a sectional view showing the conventional example, Fig. 7 is an axial a-field distribution diagram of the conventional example of Fig. 6, FIG. 8 is a cross-sectional view showing the second embodiment, and FIG. 9 is a schematic diagram showing how the electron beam spot shape deteriorates due to the barrel magnetic field. 1.2--Core protrusion, 3.4--Horizontal CY coil, 5
．． 6.-Vertical CY coil, 7...Horizontal deflection, 8
・-Vertical deflection magnetic field, 10・-Electron beam, 11-15・
... Non-uniform magnetic field curve, 31-... Deflection yoke. 77, f- 1st Ward 30th 40th 5Z 6th Ward 7th Ward 8th

Claims (1)

[Claims] 1. In a convergence device consisting of a core with one magnetic pole having two or more protrusions, a coil wound around this core, and a circuit that supplies a correction current to the coil, the generated bipolar magnetic field is converted into a substantially uniform magnetic field. A convergence device characterized by: