JP2930631B2 - Deflection yoke - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection yoke used for, for example, a video display device or a video game device, and more particularly to effectively reducing unnecessary radiation generated from the deflection yoke. Regarding means that can be done.

BACKGROUND ART Sources of unnecessary radiation in a video display device and the like include a deflection coil, a flyback transformer, and other coils. Among them, a main source is a deflection yoke.

Unwanted radiation generated from the deflection yoke is a magnetic field induced by a saw-tooth waveform current flowing in the horizontal deflection coil during the horizontal flyback period. Various methods have been conventionally proposed as methods for preventing unnecessary radiation generated by the deflection yoke, one example of which is described in JP-A-62-82633.

The invention described in this publication eliminates unnecessary radiation generated from a fringe portion between a front end (a panel side end of a cathode ray tube) and a rear end (a neck side end of a cathode ray tube) of a club-shaped horizontal deflection coil. It is like that. More specifically, a canceling coil that is substantially the same as the horizontal deflection coil is used, and this cancel coil is connected in series to the horizontal deflection coil, and is generated at the front end and the rear end fringe of the cancel coil. It is intended to cancel the induced magnetic field generated from the fringes at the front and rear ends of the horizontal deflection coil with a magnetic field, that is, unnecessary radiation.

[Problems to be Solved by the Invention] The cancel coil is mounted symmetrically in the upward and downward directions near the front end of the deflection yoke. However, when the deflection yoke is attached to the cathode ray tube and there is no external magnetic material such as a magnetic shield plate around the cathode ray tube, the magnetic flux generated from the cancel coil becomes symmetrical, and unnecessary radiation is reduced over the entire circumference of the cathode ray tube. It is possible.

However, in actual video display devices, the outer periphery of the chassis is often covered with a magnetic shield plate in order to reduce unnecessary radiation emitted from components other than the deflection yoke. Therefore, when a deflection yoke in which a canceller coil attached to a cathode ray tube is placed in a video display device and unnecessary radiation values are measured, the unnecessary radiation values become large at certain locations due to the installation of the magnetic cider plate. There is a worry that the human body is adversely affected.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a deflection yoke with extremely small unnecessary radiation.

Means for Solving the Problems In order to achieve the above object, the present invention provides, for example, a deflection system in which a pair of club-shaped horizontal deflection coils and a pair of club-shaped vertical deflection coils are arranged inside a wrapper-shaped core. A deflection yoke such as a yoke or a deflection yoke in which a pair of toroidal vertical coils are wound around a wrapper core, and a plurality of deflection yokes, for example, one symmetrically in the upward and downward directions, disposed near the front end of the core of the deflection yoke. And a canceling coil for canceling the induced magnetic field generated from the front end and the rear end of the deflection yoke, and being disposed near the deflection yoke to unbalance the distribution state of the magnetic flux generated from the canceling coil. The present invention is directed to a deflection yoke in which a magnetic flux distribution imbalance member formed of a magnetic shield plate, other magnetic coils, and the like is combined.

Then, according to the arrangement of the magnetic flux distribution imbalance member, an angle of attachment of the cancel coil disposed near the magnetic flux distribution imbalance member with respect to the center line of the deflection yoke, and at a position away from the magnetic flux distribution imbalance member. The arrangement angle of the arranged cancel coil with respect to the center line of the deflection yoke is varied.

[Operation] If the horizontal deflection coil and the cancel coil are connected in series or parallel, or are connected to the chassis side, when a horizontal deflection current flows through the horizontal deflection coil, the current also flows into the cancel coil, and the cancel coil Generates a magnetic field. The magnetic field generated from these canceling coils reaches the region of the induced magnetic field generated from the front end of the horizontal deflection coil, and reaches the region of the induced magnetic field generated from the rear end of the horizontal deflection coil.

However, when a magnetic shield plate is attached to a video display device, the magnetic field generated from the cancel coil passes through the magnetic shield plate with higher magnetic permeability depending on how the magnetic shield plate is attached.
Therefore, the magnetic field generated from the cancel coil becomes unbalanced, and it becomes impossible to cancel out the induced magnetic field generated from the front end of the horizontal deflection coil and the induced magnetic field generated from the rear end thereof in a well-balanced manner.

The present invention provides an unbalanced distribution of a magnetic field generated from a cancel coil by arranging a magnetic flux distribution imbalance member such as a magnetic shield plate, according to an arrangement state of the magnetic flux distribution imbalance member. The mounting angle of the canceling coil arranged in the vicinity with respect to the center line of the deflection yoke and the mounting angle of the canceling coil arranged in a position away from the magnetic flux distribution imbalance member with respect to the center line of the deflection yoke were made different.

Since the distribution of the magnetic field generated from the cancel coil is generally end-spread, by adjusting the mounting angle of the cancel coil, that is, by changing the direction of the magnetic field generated from the cancel coil, the cancel coil by the magnetic flux distribution imbalance member The unbalance distribution of the magnetic field of the device itself can be effectively eliminated, and therefore, the effect of canceling unnecessary radiation by the cancel coil is ensured.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the induced magnetic field and the magnetic field 4 generated from the cancel coil when only the cathode ray tube 1 and the deflection yoke 2 are combined.
FIG. 2 is a view showing an induced magnetic field when a magnetic shield plate is added to the lower side of FIG. 1 and a state of generation of a magnetic field from the cancel coil. FIG. 3 is an upper and lower cancel coil. FIG. 7 is a diagram showing an embodiment of the present invention in which the influence of the magnetic shield plate is corrected by unbalancing the intensity of the magnetic field from the magnetic field.

In these figures, 1 is a cathode ray tube, 2 is a deflection yoke, 3 and 3 'are cancellation coils, 4 is a magnetic field generated from the cancellation coils 3, 3', 5 is an induced magnetic field generated from the deflection yoke 2, and 6 is a magnetic shield. It is a board.

In the example shown in FIG. 1, since there is no magnetic material such as a magnetic shield plate around the cathode ray tube 1 and the deflection yoke 2, the magnetic field 4 generated from the cancel coils 3, 3 'is applied to the center axis Z- of the deflection yoke 2. It is symmetric about Z. Therefore, the induced magnetic field 5 at the front end and the rear end of the deflection yoke 2 is canceled by the magnetic field 4 generated from the cancellation coils 3 and 3 ', and the unnecessary radiation value can be reduced.

However, in an actual video display device, the entire periphery or a part of the video display device is often covered with a magnetic shield plate 6 so as to reduce an induced magnetic field from coils and the like other than the deflection yoke. When the lower sides of the cathode ray tube 1 and the deflection yoke 2 are covered with a magnetic shield plate 6 as shown in FIG.
Since the canceling coils 3 and 3 'are attached to the outside of the deflection yoke 2, the magnetic field 4 is greatly influenced by the magnetic shield plate 6, and as shown in FIG.
The state of the magnetic field 4 emitted from the cancellation coils 3 and 3 'with respect to the central axis Z-Z of FIG.

Therefore, at the point A on the front side of the cathode ray tube and the point B on the rear side, the induced magnetic field 5 emitted from the deflection yoke 2 and the magnetic field 4 emitted from the cancellation coils 3 and 3 'cannot cancel each other out, and the unnecessary radiation value partially increases. .

In order to improve this, the intensity of the magnetic flux of the upper cancel coil 3 disposed on the side opposite to the magnetic shield plate 6 is lower than the intensity of the magnetic flux of the lower cancel coil 3 ′ disposed near the magnetic shield plate 6. By increasing the strength, the induction magnetic field 5 generated from the front end and the rear end of the deflection yoke 2 and the magnetic field 4 generated from the cancellation coils 3 and 3 'are increased.
, And can cancel each other to reduce unnecessary radiation values.

Next, specific means for making the magnetic flux intensity of the upper cancel coil 3 stronger than the magnetic flux intensity of the lower cancel coil 3 'will be described.

As shown in FIG. 3, the mounting angle θ of the upper cancel coil 3 is smaller than the mounting angle θ ′ of the lower cancel coil 3 ′ with respect to the center line ZZ of the deflection yoke 2 (θ ′> θ). ).

As the cancel coil, a coil in which a coil is wound on a magnetic material or a so-called coreless coil in which a magnetic material is not used can be used, but the coil in which the coil is wound on the magnetic material has a smaller number of turns. It has the feature of saving time.

Further, in the above-described embodiment, an example has been described in which the cancel coils are arranged one by one above and below the deflection yoke, but the present invention is not limited to this, and three or more cancel coils are paired. It can also be arranged around the deflection yoke. Further, even when the canceling coils are arranged upward and downward, the canceling coils may be arranged obliquely upward and downward.

Further, in the above-described embodiment, the case where the magnetic shield plate is used as the magnetic flux distribution imbalance member arranged near the deflection yoke and imbalances the distribution state of the magnetic flux generated from the cancel coil has been described. However, the present invention is not limited to this. For example, even if a magnetic field generating member such as a magnetic coil such as a horizontal size adjustment coil or a linear retainer coil is installed, the distribution state of the magnetic flux generated from the cancel coil may be imbalanced. Therefore, the present invention can be applied to such a case.

When a magnetic coil is incorporated as a magnetic flux distribution imbalance member in this manner, the magnetic flux is more distant from the magnetic coil than the strength of the magnetic flux of the cancel coil disposed near the magnetic coil, opposite to the magnetic shield plate. It is configured to weaken the intensity of the magnetic flux of the cancel coil disposed at the position.

As a specific means for adding strength to the strength of the magnetic flux of the cancel coil as described above, the coil of the cancel coil arranged at a position farther from the magnetic coil than the cancel coil arranged near the magnetic coil is used. This can be achieved by reducing the number of windings, increasing the mounting angle of the deflection yoke with respect to the center line, shortening the entire length of the coil, or changing the shape.

[Effects of the Invention] The present invention is configured as described above, and increases the unnecessary radiation value due to external magnetic influences such as a magnetic shield plate, and reduces the intensity of the magnetic flux generated from each cancellation coil accordingly. By unbalancing, it is possible to correct external magnetic influences such as a magnetic shield plate and to effectively and easily reduce unnecessary radiation values.

[Brief description of the drawings]

FIG. 1 is a diagram showing an induction magnetic field and a state of generation of a magnetic field from a cancel coil when a magnetic shield plate is not provided in a combination of a cathode ray tube and a deflection yoke, and FIG. FIG. 3 is a diagram showing an induced magnetic field and a state of generation of a magnetic field from the cancel coil when added, and FIG. 3 is a diagram showing an unbalanced intensity of a magnetic flux generated from the upper and lower cancel coils to reduce a magnetic influence by the magnetic shield plate. FIG. 4 is a diagram showing a corrected embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... CRT, 2 ... Deflection yoke 3, 3 '... Cancel cell, 4 ... Magnetic field generated from cancellation coil, 5 ... Induction magnetic field, 6 ... Magnetic shield plate, Z ... Center of deflection yoke Line, θ, θ '…… The mounting angle of the cancel coil.

Continuation of front page (56) References JP-A-62-82632 (JP, A) JP-A-63-64250 (JP, A) JP-A 62-74743 (JP, U) JP-A 62-1558752 (JP , U) (58) Field surveyed (Int. Cl. ⁶ , DB name) H01J 29/46-29/82

Claims (1)

(57) [Claims] 1. A deflection yoke, a plurality of deflection coils arranged near a front end of a core of the deflection yoke for canceling an induced magnetic field generated from a front end and a rear end of the deflection yoke; A deflection yoke, which is arranged and combined with a magnetic flux distribution imbalance member that imbalances a distribution state of a magnetic flux generated from the cancel coil, wherein the magnetic flux distribution imbalance member is arranged in accordance with the arrangement of the magnetic flux distribution imbalance member. And the mounting angle of the canceling coil disposed near the center line of the deflection yoke with respect to the center line of the deflection yoke is different from the mounting angle of the cancel coil disposed at a position away from the magnetic flux distribution imbalance member with respect to the center line of the deflection yoke. A deflection yoke, characterized in that: