JPH0832982A - Deflection yoke and cathode-ray tube device - Google Patents

Abstract

PURPOSE:To provide a deflection yoke and a cathode-ray tube device which cope with even differences of devices, parts arrangements, etc., by providing a driving current adjusting means which adjusts the driving current of a cancel coil. CONSTITUTION:With respect to a variable inductor 7, a core 9 screwed into a coil bobbin is rotated to vary the extent of insertion of the core 9 to an air-core coil 8, thus varying the inductance. A horizontal deflection current (i) flowing to a horizontal deflection coil 10 is branched and flows to a cancel coil 6 and the variable inductor 7, and an inductance L of the inductor 7 is varied to vary the shunt ratio between the coil 6 and the inductor 7. As the result, a horizontal deflection current il flowing to the coil 6 is changed. Thus, the inductance L of the variable inductor 7 is adjusted to adjust the intensity of the cancel magnetic field while measuring the leakage magnetic field on the cathode-ray tube device, and the leakage magnetic field leaked out of the device is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection yoke and a cathode ray tube device, and is particularly suitable for application when canceling a leakage magnetic field (that is, a VLF magnetic field) leaking to the outside by using a cancel coil. .

[0002]

2. Description of the Related Art Conventional cathode ray tube devices include a cancel coil for reducing a leakage magnetic field leaking to the outside. That is, the cathode ray tube device such as a display device of a computer terminal is designed to electromagnetically deflect the cathode ray by the deflection magnetic field generated in the deflection yoke, and has a characteristic that a leakage magnetic field is generated from this deflection yoke.

For this reason, in this type of cathode ray tube device, a cancel coil composed of an air-core coil having a predetermined number of turns is arranged above and below the deflection yoke, and the cancel coil and the horizontal deflection coil are connected in series to cancel the cancel coil. Drive the coil with horizontal deflection current. As a result, this cathode ray tube device cancels the leakage magnetic field of the horizontal deflection magnetic field,
A canceling magnetic field is generated by this canceling coil to reduce the leaking magnetic field leaking to the outside of the cathode ray tube device.

[0004]

By the way, as described above, the leakage magnetic field of the deflection yoke naturally changes depending on the driving condition of the deflection yoke. Therefore, in order to reduce the leakage magnetic field leaking to the outside of the cathode ray tube device, the strength of the canceling magnetic field required also changes depending on the driving condition of the deflection yoke. Therefore, if the driving conditions of the cathode ray tube differ, it is necessary to newly select not only the characteristics of the deflection yoke but also the number of turns of the cancel coil.

However, the leakage magnetic field leaking to the outside of the cathode ray tube device is distributed and intensified not only by the driving condition of the deflection yoke, but also by the arrangement of components inside the device, particularly the arrangement of the shield plate around the cathode ray tube. There is a feature that changes. In addition, when these components are changed due to the leakage magnetic field generated not only by the deflection yoke but also by the components that make up the horizontal deflection circuit such as the flyback transformer, the layout of these components is also changed. Even in this case, there is a feature that the distribution and strength of the leakage magnetic field leaking to the outside change. Therefore, even if the driving conditions of the cathode ray tube are the same and the same characteristics are required for the deflection yoke, the cancel coil may have different canceling magnetic field strengths.

In this case, at the manufacturing site, it is necessary to prepare deflection yokes having the same convergence characteristics and different numbers of turns of the cancel coil, which eventually leads to an increase in the types of deflection yokes and complicated management. There is.

When the arrangement of parts inside the apparatus changes in this way, the strength of the necessary canceling magnetic field also changes, so that, for example, when the shape of the shield plate around the cathode ray tube is changed at the prototype stage, It is necessary to reconsider the number of turns of the cancel coil. In this case, arrange a deflection yoke with a different number of turns of the cancel coil,
Further, it is necessary to actually measure the leakage magnetic field strength outside the device by using this deflection yoke, which eventually causes a problem that the period required for design becomes long.

The present invention has been made in consideration of the above points, and when the leakage magnetic field outside the device is reduced by using the cancel coil, it is possible to deal with the case where the device, the arrangement of parts, etc. are different. It is intended to propose a yoke and a cathode ray tube device.

[0009]

In order to solve such a problem, in the present invention, a deflection coil 10 for generating a deflection magnetic field is provided.
And a cancel coil 6 for generating a cancel magnetic field for reducing the leakage magnetic field of the deflection magnetic field, and a drive current adjusting means 7 for adjusting the drive current of the cancel coil 6.

In this case, the drive current adjusting means 7 is composed of a variable inductor connected in parallel with the cancel coil 6.

Further, according to the present invention, in the cathode ray tube device having the cancel coil 6 for generating the cancel magnetic field and reducing the leakage magnetic field of the deflection magnetic field by the cancel magnetic field, the drive current for adjusting the drive current of the cancel coil 6 is driven. The current adjusting means 7 is provided.

In this case, the drive current adjusting means 7 is composed of a variable inductor connected in parallel with the cancel coil 6.

[0013]

If the deflection yoke 1 is provided with the drive current adjusting means 7 for adjusting the drive current of the cancel coil 6, the strength of the cancel magnetic field generated by the cancel coil 6 can be freely adjusted as necessary. it can.

If the drive current adjusting means 7 is formed by the variable inductor 7 connected in parallel to the cancel coil 6, the drive current of the cancel coil 6 can be adjusted with a simple structure.

Further, in the cathode ray tube device having the cancel coil 6, if the drive current adjusting means 7 for adjusting the drive current of the cancel coil 6 is provided, the canceling magnetic field generated by the cancel coil 6 on the cathode ray tube device side is eliminated. The strength can be freely adjusted as needed.

Further, if the drive current adjusting means 7 on the cathode ray tube device side is also formed by the variable inductor 7 connected in parallel to the cancel coil 6, the drive current of the cancel coil 6 can be adjusted with a simple structure. .

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 2, reference numeral 1 denotes a deflection yoke as a whole, in which a horizontal deflection coil is wound around a separator 2 forming a coil bobbin, and then a core 3 around which a vertical deflection coil is wound is attached to the separator 2. Then front cover 4
And the back cover 5 is attached and formed. The back cover 5 is formed with a plate-shaped coil holding plate (not shown) so as to extend vertically above and below the core 3, and further has a substantially rectangular wall surface that rises from the coil holding plate toward the core 3.
A rib is formed so as to spread outward at the tip of the wall surface, and the coil holding plate, the wall surface and the rib form a coil bobbin of the cancel coil.

In this embodiment, the deflection yoke 1 is formed by winding a litz wire to form a horizontal deflection coil, and the coil bobbin of the cancel coil is made of the same wire rod as the horizontal deflection coil, 0.15 [φ]. The litz wire is wound to form the cancel coil 6.

Further, among the coil holding plates arranged above and below, the upper surface of the coil holding plate arranged above is
A variable inductor is arranged, and in this embodiment, the variable inductor is adjusted to adjust the leakage magnetic field leaking to the outside of the cathode ray tube device.

As shown in FIG. 3, the variable inductor 7 has an air-core coil 8 formed by winding a litz wire having a wire diameter of 0.15 [φ] made of the same wire material as the horizontal deflection coil on a coil bobbin. After that, the ferrite core 9 is screwed inside the coil bobbin. This core 9
Has a cylindrical shape as a whole, and a groove is formed in a thread shape on the peripheral side surface thereof. The coil bobbin of the variable inductor 7 has a continuous protrusion corresponding to the groove of the core 9 so that the core 9 can be screwed. Are formed on the inner surface.

As a result, the variable inductor 7 can rotate the core 9 screwed into the coil bobbin to change the insertion amount of the core 9 with respect to the air-core coil 8, thereby changing the inductance. It is designed to be able to.

As shown in FIG. 1, the variable inductor 7 has a horizontal deflection coil which is formed by connecting cancel coils 6 arranged above and below the core 3 in series and then connecting the cancel coils 6 connected in series in parallel. 10 is connected in series. As a result, the cancel coil 6 can adjust the strength of the cancel magnetic field by varying the inductance of the variable inductor 7.

That is, in the solenoid coil such as the cancel coil 6, the internal magnetic field H can be expressed by the following equation. Here, n is the number of turns of the coil, and I is the current value.

[Equation 1] As a result, as in the conventional case, the number of windings of the cancel coil is n.
It can be seen that the canceling magnetic field strength can be varied by varying However, from equation (1), it can be seen that the strength of the canceling magnetic field can be varied by varying not only the number of windings n but also the current value I.

As a result, when the cancel coil 6 and the variable inductor 7 are connected in parallel as shown in FIG. 1, the currents flowing through the cancel coil 6 and the variable inductor 7, respectively, are i1 and i2. The following equation,

[Equation 2] And the inductance of the horizontal deflection coil 10 is sufficiently larger than the combined impedance of the cancel coil 6 and the variable inductor 7,
Assuming that a substantially constant voltage e is applied to the parallel circuit of the cancel coil 6 and the variable inductor 7, the equation (1) is modified to approximate the following equation.

(Equation 3) The relational expression of can be obtained. Therefore, this equation (3) is transformed to the following equation,

[Equation 4] Can be obtained, and the inductance L of the variable inductor 7 gives

(Equation 5) It can be seen that the current value i1 of the cancel coil 6 can be varied within the range represented by.

A variable resistor may be used instead of the variable inductor as the current adjusting means of the cancel coil 6, but when the variable resistor is used as described above, the horizontal deflection current is relatively large. Therefore, unless a large-sized variable resistor is used, an accident such as burnout may occur, and the resistance value and capacitance value of the variable resistor may change the convergence characteristics and the like.

On the other hand, when the current value of the cancel coil is varied by using the variable inductor as in this embodiment, the current value can be safely varied with a simple structure, and the change of the convergence characteristic or the like can be achieved. Can be effectively avoided.

4 to 6 show actual measurement results when the inductance L of the variable inductor 7 is varied in a 17-inch cathode ray tube device having a horizontal deflection frequency of 61.35 [KHz] and a vertical deflection frequency of 76.02 [Hz]. Show. Here, in FIGS. 4 to 6, the direction of 0 degrees represents the front surface of the cathode ray tube, and the direction of 180 degrees represents the set back surface.

FIG. 4 shows the measurement result of the leakage magnetic field in the state where the variable inductor is removed. In this case, the strength of the canceling magnetic field is too strong, so that the leakage magnetic field strength is about 10 [nT] in front of the set. Reduced to
It can be seen that the leakage magnetic field strength reaches about 18 [nT] at the back of the set.

On the other hand, in FIG. 5, the wire diameter is 0.15 [φ], 1
This is the result of actually measuring the variable inductor having a maximum inductance of 9.17 [μH] by winding 20 turns of four litz wires and mounting the variable inductor in the set of FIG. In this case, the strength of the canceling magnetic field is reduced by this variable inductor, and the distribution of the leakage magnetic field from the back surface to the front surface is 6 to 7 [nT] as compared with the case of FIG.
You can see that it has moved. As a result, it can be seen that by adjusting this variable inductor, the distribution of the leakage magnetic field can be varied so as to be distributed evenly over all angles, and as a result, the leakage magnetic field can be reduced.

In addition, FIG. 6 shows that the litz wire from 14 wires is wound 40 turns with a wire diameter of 0.15 [φ] to maximize the inductance.
A variable inductor of 14.2 [μH] was manufactured, and the variable inductor was mounted on the set of FIG. 4 and actually measured. Also in this case, similarly to the case of FIG. 5, it can be seen that the variable inductor can be adjusted to vary the distribution of the leakage magnetic field so as to be uniformly distributed over all angles, and as a result, the leakage magnetic field can be reduced.

Incidentally, this type of leakage magnetic field is required to have a leakage magnetic field strength of 20 [nT] or less for all measurements around the entire circumference of the set. In the case of FIG. May deviate from this standard,
In the cases of FIGS. 5 and 6, it is understood that a sufficient margin is provided for this standard.

In the above configuration, the horizontal deflection coil 10
The horizontal deflection current i flowing through the split coil flows in the cancel coil 6 and the variable inductor 7 in a shunt manner. By changing the inductance L of the variable inductor 7, the shunt ratio between the cancel coil 6 and the variable inductor 7 is changed, The horizontal deflection current i1 flowing through the cancel coil 6 changes. Thereby, for example, the intensity of the canceling magnetic field can be adjusted by adjusting the inductance L of the variable inductor 7 while mounting on an actual cathode ray tube device and measuring the leakage magnetic field intensity, and reducing the leakage magnetic field leaking to the outside of the device. can do.

According to the above configuration, the cancel coil 6
By connecting a parallel circuit of the inductor and the variable inductor 7 to the horizontal deflection coil and adjusting the variable inductor 7 so that the deflection current flowing in the cancel coil 6 can be adjusted, the strength of the cancel magnetic field can be freely selected. This makes it possible to reduce the leakage magnetic field leaking to the outside of the cathode ray tube device even when the device, the arrangement of parts, etc. are different. Therefore, it is possible to effectively avoid an increase in the types of deflection yokes to be managed at the manufacturing site or the like, and it is possible to shorten the design man-hours at the design site.

In the above embodiment, the variable inductor is arranged on the deflection yoke side, but the present invention is not limited to this, and it may be arranged on the set side.

Further, in the above embodiment, the case where the variable inductor is used as the drive current adjusting means 7 of the cancel coil 6 has been described, but the present invention is not limited to this, and the taps are switched in the inductors forming the shunt circuit. Various drive current adjusting means 7 can be widely applied, for example, when the diversion ratio is changed stepwise.

[0037]

As described above, according to the present invention, by providing the drive current adjusting means for adjusting the drive current of the cancel coil, even if the device, the arrangement of parts and the like are different, the cathode ray tube device can be provided correspondingly. It is possible to obtain the deflection yoke and the cathode ray tube device capable of reducing the leakage magnetic field leaking to the outside.

[Brief description of drawings]

FIG. 1 is a connection diagram showing a connection of a cancel coil according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a deflection yoke to which the cancel coil of FIG. 1 is applied.

FIG. 3 is a schematic diagram showing a variable inductor applied to the deflection yoke of FIG.

FIG. 4 is a characteristic curve diagram showing a measurement result of a leakage magnetic field when a variable inductor is not attached.

FIG. 5 is a characteristic curve diagram showing a measurement result of a leakage magnetic field when a variable inductor having an inductance of 9.17 [μH] is attached.

FIG. 5 is a characteristic curve diagram showing a measurement result of a leakage magnetic field when a variable inductor having an inductance of 14.2 [μH] is mounted.

[Explanation of symbols]

 1 Deflection Yoke 2 Separator 3, 9 Core 5 Back Cover 6 Cancellation Coil 7 Variable Inductor 8 Air-Core Coil 10 Horizontal Deflection Coil

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[Procedure amendment]

[Submission date] October 7, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a connection diagram showing a connection of a cancel coil according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a deflection yoke to which the cancel coil of FIG. 1 is applied.

FIG. 3 is a schematic diagram showing a variable inductor applied to the deflection yoke of FIG.

FIG. 4 is a characteristic curve diagram showing a measurement result of a leakage magnetic field when a variable inductor is not attached.

FIG. 5 is a characteristic curve diagram showing a measurement result of a leakage magnetic field when a variable inductor having an inductance of 9.17 [μH] is mounted.

FIG. 6 is a characteristic curve diagram showing a measurement result of a leakage magnetic field when a variable inductor having an inductance of 14.2 [μH] is mounted.

[Explanation of reference symbols] 1 deflection yoke 2 separator 3, 9 core 5 back cover 6 cancellation coil 7 variable inductor 8 air-core coil 10 horizontal deflection coil

Claims (4)

[Claims] 1. A deflection coil for generating a deflection magnetic field, a cancel coil for generating a canceling magnetic field for reducing a leakage magnetic field of the deflection magnetic field, and drive current adjusting means for adjusting a drive current of the cancel coil. Deflection yoke characterized by. 2. The deflection yoke according to claim 1, wherein the drive current adjusting means is a variable inductor connected in parallel to the cancel coil. 3. A cathode ray tube device having a cancel coil for generating a cancel magnetic field, wherein the leak magnetic field of a deflection magnetic field is reduced by the cancel magnetic field, wherein a drive current adjusting means for adjusting a drive current of the cancel coil. A cathode ray tube device comprising: 4. The cathode ray tube device according to claim 3, wherein the drive current adjusting means is a variable inductor connected in parallel to the cancel coil.