JPS63176079A - Beam spot correction circuit - Google Patents

Abstract

PURPOSE:To correct the inclination of a beam spot at the corner of the tube surface of a cathode ray tube by connecting a correcting coil for the inclination of the spot in series to a controlled coil, and modulating the impedance of the coil to be controlled differentially at a vertical period by means of supplying a vertical deflection current to the control coil of a satuable reactor. CONSTITUTION:The coils L1, L2, and the coils L3, L4 are connected in parallel, and the spot inclination correcting coil, i.e., a rotation coil 3 is connected in series to the coils L1, L2 and the coils L3, L4 respectively. Then, by supplying a horizontal deflection current i1 to the coils L1, L2 to be controlled of the satuable reactor 4 and to the rotation coil RC1, and the horizontal deflection current i2 to the coils L3, L4 to be controlled and the rotation coil RC2, and the vertical deflection current i3 to the control coil L5 respectively, the impedance of the coils L1-L4 to be controlled is modulated differentially at the vertical period. Thus, while the beam scans the upper part of the tube surface, a magnetic field due to the coil RC2 is dominant and corrects the inclination of the spot.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a beam spot correction circuit suitable for use in, for example, a television receiver.

[Summary of the invention]

This invention connects a plurality of controlled coils of a saturable reactor in series with a horizontal deflection coil, connects a spot tilt correction coil in series with the controlled coil, and applies a vertical deflection current to the control coil of the saturable reactor. The inclination of the beam spot at the corner of the tube surface of the cathode ray tube is corrected by differentially modulating the impedance of the controlled coil with a vertical period.

[Conventional technology]

For example, the center spot of a beam index type cathode ray tube (index tube) is a vertically long beam as shown in Figure 7, so if it is deflected using a narrow deflection yoke,
As shown in the figure, it tilts at the corner (C+e+L1). Therefore, at present, in order to eliminate the spot inclination at the corners, the horizontal and vertical image fields are distorted into a bottle cushion shape.

[Problem that the invention seeks to solve]

Therefore, conventionally, a so-called low tension coil or quadrupole coil is attached to the neck of the cathode ray tube to dynamically correct the inclination of the suboft at each corner of the tube surface. Since a dedicated drive circuit is required to drive the four-electrode coil, there are drawbacks such as a complicated circuit configuration and high cost.

Additionally, when the magnetic field is distorted, the spots d and h in Figure 7 extend vertically, resulting in poor resolution at the y ends (top and bottom edges of the screen), and the spots d and f in Figure 7 extend vertically. It had the disadvantage that it shrunk and became thicker, resulting in poor color purity at the X end (the left and right ends of the screen).

This invention has been made in view of the above, and provides a beam spot correction circuit that has a simple configuration and can correct the inclination of the spot at each corner of the tube surface without distorting the spot at the X end or the Y end. It is something.

[Means for solving problems]

The beam spot correction circuit according to the present invention connects a plurality of controlled coils (Ll, L2, Ll, L4) of a saturable reactor (4) in series with a horizontal deflection coil (9),
Spot tilt correction coil (3) in series with the controlled coil
and the control coil (L5) of the saturable reactor (4)
A vertical deflection current (i3) is supplied to the controlled coil (LL
, L2, Ll, L4) are differentially modulated in a vertical period.

[Effect]

A plurality of controlled coils (Ll, L2.L:1.L4) of the saturable reactor (4) in series with the horizontal deflection coil (9).
) to connect them in a parallel relationship. That is, the coils L1+L2, Ll, and L4 are connected in parallel. And coil L1. L
A spot tilt correction coil, that is, a rotation coil (3), is connected in series with L1, L4, and L4. The controlled coils (Ll, L2) of the saturable reactor (4)
) and rotijohn coil (RCL), horizontal deflection current (i2) to the controlled coil (Ll, L4) and rotijohn coil (RC2), and vertical deflection current (i3) to the control coil (L5). ) to control the controlled coils (Ll, L2, La, L4), respectively.
) is differentially modulated with a vertical period.

In other words, by changing the polarity combinations of the horizontal deflection current (ilr i2) and the vertical deflection current (i3), the controlled coils (Lx, L2, Ll, L4) are saturated in correspondence with the quadrants of each tube surface. Lower impedance.

As a result, when the beam is scanning the upper part of the tube surface, l
As i2 l>lit l, the magnetic field by the rotary john coil (RC2) becomes dominant, and when the beam is scanning the lower part of the tube surface, the magnetic field by the rotary john coil (RCL) becomes dominant as lil 1>1121, and the spot Correct the tilt of.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on FIGS. 1 to 6.

First, the basic principle of this invention will be explained with reference to FIGS. 4 to 6.

In Figure 4, there is a saturable connection between the deflection yoke (horizontal deflection coil and vertical deflection coil) (2) provided at the neck of the cathode ray tube +11 (to be precise, the horizontal deflection coil and the vertical deflection coil) (2) and the spot tilt correction coil, such as the rotation coil (3). Reactor (4)
will be established. The rotation coil (3) consists of two coils RC1 and RC2, which are wound with a pie filer, for example, and are actually not separate (but integrated) as shown in the figure.The coils RC> and RC2 are the fourth It is attached to the neck of a cathode ray tube (1) in the winding direction as shown in the figure, and the magnetic fields created by currents 11 and 12 flowing through each coil RC1 and RC2 are opposite to each other as shown by arrows a and b, so 11
When 11-If2 +, no magnetic field is generated.

In order to correct the inclination of the spot that occurs in the first quadrant I of the tube surface of the cathode ray tube (1) shown in Fig. 4 (corresponding to the inclination of the spot in C in Fig. 7), the magnetic field from coil RC2 becomes dominant, The magnetic field distribution may be such that the direction of magnetic flux passing through RC2 is from the tube surface toward the neck portion. To do this, the relationship between the currents 11 and 12 flowing through the coils RCz and RC2 is set to 1121>lil 1.

In order to correct the inclination of the spot that occurs in the second quadrant of the tube surface of the cathode ray tube (1) shown in Fig. 4 (corresponding to the inclination of the spot at e in Fig. 7), the magnetic field by the coil RC2 becomes dominant, and the magnetic field generated by the coil RC2 becomes dominant. The magnetic field distribution may be such that the direction of the magnetic flux is from the neck toward the tube surface, opposite to the first quadrant. To do this, current 1 is passed through coils RC1 and RC2.
Let the relationship between 1 and 12 be lil 1>lit l.

In other words, when the beam is scanning the upper part of the tube surface, the current is 1
The relationship between 1 and 12 should be l it1 > l it 1, and the current waveform in this case is as shown in Figure 5. In Figure 5, the upper right corresponds to the first quadrant, and the lower left corresponds to the first quadrant. It corresponds to 2 quadrants.

In order to correct the inclination of the spot (corresponding to the inclination of the spot at g in Fig. 7) that occurs in the third quadrant (3) of the tube surface of the cathode ray tube (1) shown in Fig. 4, the magnetic field by the coil RC1 becomes dominant, and the coil The magnetic field distribution may be such that it does not penetrate RC1 (the direction of the magnetic flux is from the tube surface to the neck part).For this purpose, the relationship between the currents 11 and 12 flowing through the coils RCL and RC2 is set as lil>it2l.

In order to correct the inclination of the spot (corresponding to the inclination of the spot in i in Fig. 7) that occurs in the fourth quadrant (2) of the tube surface of the cathode ray tube (1) shown in Fig. 4, the magnetic field by the coil RC> becomes dominant. The magnetic field distribution may be such that the direction of the magnetic flux passing through the coil RC1 is from the neck toward the tube surface, opposite to the third quadrant. For that purpose, current 11 and ! 2 is set as Itl 1>it2 1.

In other words, when the beam is scanning the lower part of the tube surface, the current is 1
The relationship between 1 and 12 may be l ts l>l it1, and the current waveform at this time is shown in FIG. In FIG. 6, the upper right corresponds to the fourth quadrant, and the lower left corresponds to the third quadrant.

Further, when the beam is scanning the center of the tube surface, no magnetic field may be generated. For that, coil R
The relationship between the currents 11 and 12 flowing through C1 and RC2 is 1i, I=li-i.

Therefore, in this invention, a saturable reactor (4) is provided between the deflection yoke (2) and the rotation coil (3), and when the beam is scanning the upper part of the tube surface by this reactor (4), +12 1> lit I, and when the beam is scanning the lower part of the tube surface, the current relationship is controlled so that lil 1>lil l, and the inclination of the spot at the corner of the tube surface is eliminated.

FIG. 1 shows the configuration of an embodiment of the present invention, in which a reactor (4) has cores (5) and (6), and these cores (
Magnet 7N installed on both sides of 5) and (6) respectively? )
and (8), and coils 1 to L4 as controlled coils.
and a coil L5 as a control coil.

The coils L1 and L2 are wound around the cores (5) and (6), respectively, and one end of the coil L□ is connected to the horizontal deflection coil +11.
The other end of the coil LL is connected to one end of the coil L2, and the other end of the coil L2 is connected to one end of the coil RCs. In addition, the cores L3 and L4 are each core (
5) and (6), one end of the coil L3 is connected to one end of the horizontal deflection coil (9), the other end of the coil L3 is connected to one end of the coil 4; The other end is connected to one end of the coil RC2. Also, coil L5
is wound across the cores (5) and (6) in its central part, one end of the coil L5 is connected to one end of the vertical deflection coil (10), and the other end of the coil L5 is connected to the negative power terminal. be done. Note that a vertical deflection current i3 flows through the coil L5.

Figure 2 shows the equivalent circuit of Figure 1.
S constitutes a control coil, whereas coils L1 to L4
constitutes a controlled coil.

Next, the operations shown in FIGS. 1 and 2 will be explained for each quadrant. Here, the beam moves to the position of the first quadrant of the tube surface when ix>Q, it>Q, i3>O, and the coil (9) and (
10) is placed.

When the beam is scanning the first quadrant, the relationship between the currents is i
l>Q, it>0. Let ix > 0. Then, as shown in FIG. 3, a total of three types of magnetic flux penetrate through the coils 1 to L4: the magnetic field due to the currents i1 to i3 and the magnetic flux due to the magnets (7) and f8). In Fig. 3, the solid line is the magnetic flux due to the current i3, and the broken line is the magnetic flux due to the magnet h (71, (81
The dashed line is the magnetic flux due to the current i or 12.

As can be seen from FIG. 3, all the magnetic fluxes passing through the coil L3 are in the same direction, so the coil L3 is saturated.

(To be exact, adjust the magnetic bias of Magneso [7) and (81) so that the coil is saturated only when all three types of magnetic flux are in the same direction.) When coil L3 is saturated, its impedance decreases. L3 <Lx =L
2-L4, and as a result, 1 i21>I ti I, the magnetic field by coil RC2 becomes dominant, and the direction of magnetic flux passing through coil RC2 goes from the tube surface to the neck, so the spot in the first quadrant of the tube surface The slope of is corrected. .

When the beam is scanning the second quadrant, the relationship between the currents is i
l<0. Let i2<(L il>0. In this case, the direction of the current i<r>12 is opposite to that in the first quadrant, so the direction of the magnetic flux generated by the current 11+t2 in Fig. 3 is the same as in Fig. 3. It will be the opposite.

Therefore, all the magnetic flux passing through the coil 4 is in the same direction, so the coil 4 becomes saturated and its impedance decreases to become L4 < LL = L 2 = La. The result is <1i21>1111, which is the same as in the first quadrant,
The magnetic field due to coil RC2 is dominant, but the current is 11+t
2 is reversed, the direction of the magnetic flux passing through the coil RC2 is from the neck toward the tube surface, opposite to the first quadrant, and the inclination of the spot in the second quadrant of the tube surface is corrected.

When the beam is scanning the third quadrant, the relationship between the currents is i
l<Q, i2<0. Let il <O. In this case, the directions of the currents 11, 12 + t3 are all opposite to those in the first quadrant, so the directions of the magnetic flux generated by the current 11 + j2 and the magnetic flux generated by the current i3 in Figure 3 are opposite to those in Figure 3. . Therefore, all the magnetic flux passing through the coil L2 is in the same direction, so the coil L2 becomes saturated and its impedance decreases, so that L2 < LL = L3 =
It becomes L4.

As a result, l is l>I i21, which is opposite to the first quadrant, and the magnetic field by coil RC1 becomes dominant, and the direction of magnetic flux passing through coil RC1 goes from the tube surface to the neck, so in the third quadrant of the tube surface The tilt of the spot is corrected.

When the beam is scanning the fourth quadrant, the relationship between the currents is i
Let l>O, i2>O, il<0. In this case the current i
3 is opposite to that in the first quadrant, the direction of the magnetic flux generated by the current i3 in FIG. 3 is opposite to that in FIG. 3. Therefore, all the magnetic flux flowing through the coil L1 is in the same direction, so the coil L1 becomes saturated and its impedance decreases, so that LL < L2 = L3 = L4. As a result, contrary to the first quadrant, l is l>l i2
1, and the magnetic field by coil RC1 becomes dominant,
Since the direction of the magnetic flux passing through the coil RC1 is from the tube surface toward the neck portion, contrary to the case of the third quadrant, the inclination of the spot in the fourth quadrant of the tube surface is corrected.

In the above-described embodiment, a rotation coil is used as the spot tilt correction coil, but other coils capable of achieving the same function, such as a quadrupole coil, may be used.

〔Effect of the invention〕

As described above, according to the present invention, a plurality of controlled coils of the saturable reactor are connected in series with the horizontal deflection coil, a spot tilt correction coil is connected in series with the controlled coils, and the control coil of the saturable reactor is connected in series with the horizontal deflection coil. Since the impedance of the controlled coil is differentially modulated in a vertical period by supplying a vertical deflection current to the The inclination of the spot at each corner of the tube surface can be corrected without distorting the image.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of FIG. 1, FIG. 3 is a diagram for explaining the operation of this invention, and FIGS. 4 to 6 are A diagram for explaining the basic principle of this invention, and FIG. 7 is a diagram for explaining a conventional example. (3) is a rotary silane coil, (4) is a saturable reactor, (5) and (6) are cores, (7) and (8) are magnets, (9) is a horizontal deflection coil, and (10) is a vertical deflection Coyle, Ll. L2. L3. L4 is a controlled coil, and L5 is a control coil.

Claims (1)

[Claims] A plurality of controlled coils of a saturable reactor are connected in series with the horizontal deflection coil, a spot tilt correction coil is connected in series with the controlled coils, and the control coil of the saturable reactor is connected with a spot tilt correction coil in series with the controlled coil. A beam spot correction circuit characterized in that the impedance of the controlled coil is differentially modulated in a vertical period by supplying a vertical deflection current.