JPH0832980A - Deflection yoke - Google Patents

Abstract

PURPOSE:To provide a deflection yoke which considerably reduces a beat due to oscillation caused by a control coil. CONSTITUTION:A series circuit of a diode D1 and a resistor R1 is connected in parallel to a control coil L1 connected in series to a vertical deflection coil Lv, and a vertical deflection current Iv which is dulled just after the fly-back time is supplied to the control coil L1. The control coil L1 to which this current is supplied doesn't bring about the oscillation conventionally caused in the vertical deflection period, and beat is considerably reduced. If the change range of a magnetic flux phi generated from the control coil L1 is extended and the operation range of saturable reactors L2 and L3 is extended to the saturation area in the stage of design of the deflection yoke, the change of the inductance is suppressed not to have an influence upon convergence.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection yoke used in a three-electron gun in-line type color picture tube, and more particularly to a deflection yoke capable of significantly reducing a beat noise due to vibration generated from a control coil.

[0002]

2. Description of the Related Art An in-line type color picture tube which emits three electron beams arranged in a row consisting of a center beam passing through the same horizontal plane and a pair of side beams from an electron gun, has a horizontal deflection magnetic field of a pincushion type and a vertical deflection magnetic field. By using a barrel type non-uniform magnetic field, the three electron beams arranged in a row are self-focused only by the combination of the color picture tube and the deflection yoke without using any external circuit correction means, and the entire screen is displayed. We have realized a self-convergence method that substantially matches the above.

Generally, the convergence characteristic of a self-convergence type deflection yoke is evaluated by typifying a misconvergence pattern of a pair of side beams (Red, Blue) as shown in FIG. That is, vertical line misconvergence XH on the X axis shown in FIG. 4A, vertical line misconvergence YH on the Y axis shown in FIG. 4B, and horizontal line around the screen shown in FIG. 4C. This is Miss Convergence CRS. In recent years, due to the high definition of CRT display devices, these three characteristics have become
It is difficult to satisfy only the non-uniform magnetic field by the horizontal and vertical deflection coils described above.

Therefore, in order to satisfy these three characteristics, XH and YH are corrected by horizontal and vertical deflection coils, and C
For RS, a method of correcting with a convergence correction circuit as shown in FIGS. 5 and 6 is often used. This convergence correction circuit includes a control coil L1 connected in series with a vertical deflection coil Lv and a saturable reactor L connected in series with a pair of horizontal deflection coils Lh.
2, L3 and permanent magnet Mg.

FIG. 3 shows the magnetic flux φ generated from the control coil L1 and the inductance L of the saturable reactors L2 and L3.
It is a waveform diagram showing. In FIG. 3A, the horizontal axis represents the magnetic flux φ, the vertical axis represents the inductance L in the positive direction, and the time t in the negative direction.
Represents By supplying the vertical deflection current Iv to the control coil L1, as shown in FIG. 3A, the magnetic flux φ generated from the control coil L1 changes in the range of φA in the vertical deflection cycle, and the control coil L1 is magnetically magnetized. The inductance L of the combined saturable reactors L2 and L3 is changed within the range of LA, and as a result, the horizontal deflection magnetic field is changed. That is, the horizontal deflection magnetic field is differentially changed in the vertical deflection cycle, and thereby the horizontal line misconvergence CRS around the screen is corrected.

[0006]

This saturable reactor L
In the convergence correction device using 2, L3 and the control coil L1, an unpleasant beat sound may be generated. The cause is as follows.

When the vertical deflection current Iv is passed through the control coil L1, the control coil L1 vibrates in the vertical deflection cycle. Further, the vibration is caused by the adjacent saturable reactors L2 and L3.
Or, it propagates to the container storing the saturable reactors L2 and L3 and the control coil L1 and is heard as a humming sound. Therefore, in order to reduce the beat noise generated by the vibration of the control coil L1, a conventional method is to suppress the vibration by injecting an adhesive into a container that stores the control coil L1 and the saturable reactors L2 and L3. Came.

However, this method has the following problems. 1. The inflow of the adhesive increases the number of assembly steps. 2. There was a variation in the degree of inflow of the adhesive, it was difficult to uniformly reduce the amount of growling noise, and it was impossible to maintain stable quality. Therefore, an object of the present invention is to reduce the beat noise generated by the vibration of the control coil L1 by using an electric method instead of a mechanical means such as an inflow of an adhesive.

[0009]

In order to solve the above-mentioned problems of the prior art, the present invention provides a saturable reactor connected in series to each of a pair of horizontal deflection coils, the saturable reactor and the magnetic In a deflection yoke including a circuit for correcting convergence by differentially changing a horizontal deflection magnetic field in a vertical deflection cycle, the control yoke being coupled to a pair of vertical deflection coils and a control coil connected in series. A deflection yoke is provided, in which a series circuit of a diode and a resistor is connected in parallel to the control coil and the operating range of the saturable reactor is expanded to a substantially saturated region.

[0010]

EXAMPLE The present inventor further found out the following point as a result of further elucidation of the cause of howling noise caused by the vibration generated from the control coil. FIG. 2 shows the vertical deflection current Iv
It is a waveform diagram showing. A vertical deflection current I as shown in FIG. 2A is applied to the control coil L1 of the convergence correction device.
v is flowing. As a result of conducting an experiment in which various currents obtained by deforming the vertical deflection current Iv are supplied to the control coil L1 and the vibration at that time is measured, the vibration of the control coil L1 occurs in the portion A immediately after the blanking period. It became clear that there is.

This is because the current changes rapidly during the blanking period,
Immediately after that, vibration occurs due to the occurrence of the counter electromotive force in the control coil L1 at the portion A. However, in the scanning period, the change in the current is relatively gradual as compared with the blanking period, so that almost no counter electromotive force is generated in the portion B of FIG. 2A and the control coil L1 does not vibrate. Therefore,
In the current flowing through the control coil L1, by supplying the vertical deflection current in which only the portion A is blunted as shown in FIG. 2B, the vibration of the control coil L1 can be suppressed, and the beat noise is significantly reduced. Can be made.

FIG. 1 is a circuit diagram showing an embodiment of the deflection yoke of the present invention. The same parts as those in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 1, by connecting a series circuit of a diode D1 and a resistor R1 to the control coil L1 in parallel, the control coil L1 has a vertically blunted peak portion immediately after a blanking period as shown in FIG. 2B. Deflection current is supplied. The polarity of the diode D1 is
In FIG. 2A, the forward connection is made in the direction in which the blanking period flows, that is, in the direction in which the vertical deflection current flows in the positive direction.

The operation of the deflection yoke of the present invention will be described below. The direction of the current flowing through the vertical deflection coil Lv in the drawing is in the direction of the solid line arrow when deflecting to the upper side of the screen, and in the direction of the broken line arrow when deflecting to the lower side of the screen. When the light is deflected to the lower side of the CRT screen, that is, when a negative current flows in the current waveform diagram of FIG. 2A, no current flows in the diode D1. Therefore, the circuit added according to the present invention does not affect the current flowing through the control coil L1 during the downward deflection. Next, consider a case where the image is deflected to the upper side of the CRT screen, that is, a case where a positive current flows in the current waveform diagram of FIG. Vertical deflection current is I
v, DC resistance of control coil L1 is RL1, diode D
When the forward voltage of 1 is VD,

VD <Iv × RL1

When the condition (1) is satisfied, the diode D1 becomes conductive, a current as shown in FIG. 2 (c) flows through the additional circuit, and a current flowing through the control coil L1 becomes a current as shown in FIG. 2 (b). Flows. Therefore, the portion A immediately after the abrupt change of the vertical deflection current Iv becomes dull.

However, it is necessary to prevent the inductance of the saturable reactors L2 and L3 from changing by blunting the peak portion of the vertical deflection current Iv immediately after the blanking period so as not to affect the convergence correction itself. . Therefore, at the deflection yoke design stage,
The change range of the magnetic flux φ generated from the control coil L1 shown in FIG.
The range in which the inductance of 2, L3 changes is from LA to L
It was expanded to B, that is, to the region where the inductances of the saturable reactors L2 and L3 were saturated.

When the saturable reactors L2 and L3 are operated in the range LA of FIG. 3 (a), the magnetic flux φ generated from the control coil L1 is Δφ due to the blunting of the current.
Decrease by A. Accordingly, as shown in FIG. 3B, the inductances of the saturable reactors L2 and L3 are ΔL.
A decrease, which may affect convergence.

In order to prevent this, in the design stage of the deflection yoke, the change range of the magnetic flux φ generated from the control coil L1 is expanded from φA to φB, and the operating ranges of the saturable reactors L2 and L3 are changed from LA in FIG. 3 (a). It is necessary to spread it to LB. As a result, the amount of change in the inductance is suppressed to ΔLB shown in FIG. 3B, so that it does not affect the convergence.

As a concrete method for expanding the variation range of the magnetic flux φ generated from the control coil L1 from φA to φB, the magnetic flux can be increased by increasing the inductance of the control coil L1 without increasing the current flowing through the control coil L1. The change range of φ can be widened, and as a result, the operating range of the saturable reactors L2, L3 can be widened to the saturation region.

[0020]

As described in detail above, the deflection yoke of the present invention has the following extremely excellent practical effects. 1. The beat noise due to the vibration of the control coil can be significantly reduced without affecting the convergence characteristics. 2. Since the work of inflowing the adhesive is not necessary, the number of assembling steps is reduced. 3. Since the growling noise can be reduced uniformly, it is possible to maintain stable quality.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a deflection yoke of the present invention.

FIG. 2 is a waveform diagram for explaining the operation of the book.

FIG. 3 is a waveform diagram showing a magnetic flux φ generated from a control coil L1 and an inductance L of saturable reactors L2 and L3.

FIG. 4 is a diagram showing a misconvergence pattern.

FIG. 5 is a circuit diagram showing an example of a conventional deflection yoke.

FIG. 6 is a schematic configuration diagram showing an example of a conventional deflection yoke.

[Explanation of symbols] Lh horizontal deflection coil Lv vertical deflection coil L1 control coil L2, L3 saturable reactor D1 diode R1 resistance

Claims (1)

[Claims] 1. A saturable reactor connected in series to each of a pair of horizontal deflection coils, and a control coil magnetically coupled to the saturable reactor and connected in series to a pair of vertical deflection coils. In a deflection yoke including a circuit for correcting convergence by differentially changing a horizontal deflection magnetic field in a vertical deflection period, a series circuit of a diode and a resistor is connected in parallel to the control coil, and A deflection yoke in which the operating range of the saturation reactor is expanded to a substantially saturation region.