JPH1027559A - Deflection yoke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deflection yoke for reducing misconvergence without changing the shape of a coil by enabling at least one of a plurality of coil blocks to conduct a current that is different from those for the other coil blocks. SOLUTION: A vertical deflection coil (V-coil) wound into a saddle shape, for use in a color display device, has a pair of coils divided into six coil blocks 10a1, 10b1, 10c1, 10a2, 10b2, 10c2 from the magnetic pole side to the dividing surface side. The coil blocks 10a1, 10a2 are located on the magnetic pole side, while the coil blocks 10c1, 10c2 are located on the dividing surface side. By adjusting the ratio of conducting currents among the coil blocks, the distribution of a deflecting magnetic field is varied to enable adjustments for reducing misconvergence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection yoke mounted on a cathode ray tube of a color television receiver, a color display device or the like.

[0002]

2. Description of the Related Art Generally, a deflection yoke mounted on a color picture tube having three electron guns in an in-line arrangement to deflect an electron beam generated by each electron gun has a vertical deflection coil (FIG. 4). The coil includes a V coil), a horizontal deflection coil (H coil), and a core 3. Further, depending on the method, a coil called a convergence yoke (CY) 4 is a component. A vertical deflection magnetic field and a horizontal deflection magnetic field are generated by the V coil 1 and the H coil 2 to deflect the electron beam in the vertical and horizontal directions. The core 3 is a magnetic material and plays a role of a return yoke for each deflection magnetic field. CY4 generates a magnetic field in synchronization with the V coil. FIG. 5 shows the configuration of the V coil. The V coils are coils 1a and 1
b is a pair of coils. A pair of coils 1a, 1
b generates a vertical deflection magnetic field in a direction connecting the magnetic poles 5a and 5b. Here, the surface where the coils 1a and 1b meet is referred to as a split surface 6. FIG. 6 shows the configuration of the H coil. The H coil is a pair of coils including the coils 2a and 2b.
The pair of coils 2a and 2b generate a horizontal deflection magnetic field in a direction connecting the magnetic poles 7a and 7b. Here, the coils 2a, 2
The surface where b meets is called the split surface 8.

The magnetic field generated in the direction connecting the magnetic poles 5a and 5b by the V coil 1 has a distribution called a barrel type, and the magnetic field generated in the direction connecting the magnetic poles 7a and 7b by the H coil 2 is a pincushion type (barrel type). (Pin cushion type). FIG. 7 shows the configuration of the CY. C shown here
Y4 is a structure in which coils 4b and 4c are provided on a magnetic body 4a having a circular ring and a plurality of linear portions extending from the circular ring toward the center. The coil 4b is located in the horizontal direction,
c is located in an oblique direction. A magnetic field 9 is generated by energizing the coils 4b and 4c. Ideally, the three electron beams reach the same position on the picture tube screen by the deflection magnetic field having such a distribution. When the beam reaches a position shifted on the tube surface, a state of color shift occurs. In FIG.
It shows the color shift when a rectangular figure of red R, green G, and blue B is displayed on the screen. R represents a red rectangular figure, G represents a green rectangular figure, and B represents a blue rectangular figure. Such a shift amount is called misconvergence. Misconvergence is zero in an ideal cathode ray tube.

[0004] The misconvergence depends on the shape and winding distribution of each coil for generating a deflection magnetic field. Actually, in the development of the deflection yoke, the V coil 1, the H coil 2 and the CY4
To optimize the shape and winding distribution. The effect of the winding distribution of each coil on misconvergence is different between the winding near the magnetic pole of the coil and the winding far from the magnetic pole (split surface side). Optimization is achieved by adjusting the shape and winding distribution.

However, it is difficult to make the misconvergence equal to or less than the allowable value over the entire screen. When the misconvergence at one position is reduced, the misconvergence at another position is often increased. For this reason, for example,
In Japanese Patent Laid-Open No. 64-2242, specific misconvergence is corrected by specially devising the shape and driving circuit of CY4.

[0006]

In the means for correcting a specific misconvergence of the prior art, when the misconvergence to be corrected is improved, the misconvergence at another position often changes. For this purpose, the shape and winding distribution of the V coil and H coil must be adjusted again.
That is, the shape of the winding form or the bobbin is changed, or the number of windings is partially changed. If the deflection yoke is developed by repeating the trial production many times while changing the shape and the winding distribution, there is a problem that the development period becomes long.
In addition, when mis-convergence specifications become severe due to the higher definition of color cathode-ray tubes, a deflection yoke that meets the specifications for the entire screen was developed with the conventional method of optimizing the shape and winding distribution by focusing on a specific mis-convergence It will be difficult.

It is therefore an object of the present invention to provide a deflection yoke for reducing misconvergence without changing the shape of a coil.

[0008]

In order to solve the above problems, at least one of the coil blocks of a deflection yoke formed from a plurality of coil blocks in which a plurality of coils wound in a saddle shape are bundled. The problem is solved by allowing a current different from that of the other coil blocks to flow.

[0009]

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

[0010] The V coil and the H coil are formed of a plurality of coil blocks in which a plurality of coils wound in a saddle shape are bundled. At this time, the coil block is arranged from the magnetic pole side to the split surface side. The effect of each coil block from the magnetic pole side to the split surface side on misconvergence is different. In order to adjust the influence of each coil block on misconvergence, it is possible to adjust each current value instead of adjusting the coil shape and winding distribution. Therefore, by obtaining a suitable current value for each current value, it is possible to easily develop a deflection yoke of a high-performance color cathode-ray tube having excellent misconvergence characteristics without changing the shape and winding distribution of the entire coil.

FIG. 1 shows an example of a V coil, and a plane 11 in FIG.
FIG. 2 shows a cross section of the coil of FIG. FIG. 3 shows an electric circuit diagram of this coil. In FIG. 1, as an example, six coil blocks 10 each including a pair of coils extending from the magnetic pole side to the split surface side.
a1, 10b1, 10c1, 10a2, 10b2, 10
c2. The coil blocks on the magnetic pole side are 10a1 and 10a2, and the coil blocks on the split side are 10c1 and 10a1.
c2.

By adjusting the ratio of the current flowing through each coil block, the distribution shape of the deflection magnetic field can be changed to adjust the misconvergence. Here, the adjustment of the ratio of the conduction current of each block will be described with reference to the circuit diagram shown in FIG. The upper and lower pairs of coil blocks are 10
a1,10a2 and 10b1,10b2 and 10c1,1
0c2. The blocks 10a1 and 10a2 are connected in series, and the resistors Ra1, Ra2, Rv connected in series
a is connected in parallel to these 10a1 and 10a2. To supply current to the coil blocks 10a1 and 10a2,
The resistors Ra1 and Ra2 are sufficiently large. Resistance R
va is a variable resistor, which allows the coil block 10a
The current balance of 1, 10a2 is adjusted. Similarly, coil blocks 10b1, 10b2 and 10c1, 10c
2 have resistors Rb1, Rb2, Rvb and Rc1, Rc2, R
vc. Further, the resistances Ra, Rv1, Rv
2 to constitute the entire circuit. Resistance Rv1, Rv2
Is a variable resistor. By adjusting Rv1 and Rv2, the ratio of the resistors R1, Rv1, and Rv2 can be specified, and thereby the ratio of the current flowing through each coil block can be adjusted. Since the deflection frequency of the V coil is a low frequency of about 40 to 120 Hz, the connection circuit uses a resistor as a current adjusting element, and is the circuit shown here.

FIG. 9 is a circuit diagram when the CY of FIG. 7 is further combined with the above-described V coil. CY shown in FIG.
9 to adjust the ratio of the current of the coil 4b positioned in the horizontal direction to the current of the coil 4c positioned in the oblique direction.
Includes a variable resistor Rvcy. By adjusting the resistance, the characteristics of the magnetic field generated by the CY can be changed.

Next, as an example of the H coil, FIG. 10 shows a cross section of the coil corresponding to FIG. FIG. 11 shows an electric circuit diagram of this coil. In FIG. 10, as an example, one coil of a pair of coils is divided into three coil blocks 13a1, 13b1, and 13c1 from the magnetic pole side to the split surface side. The coil block on the magnetic pole side is 13a1, and the coil block on the split surface side is 13c1. The other coil block 13a2, 13b2, 13c2 on the other side is also shown. By adjusting the ratio of the current flowing through each coil block, the distribution shape of the deflection magnetic field can be changed to adjust the misconvergence. Here, the adjustment of the ratio of the conduction current of each block will be described with reference to FIG. The deflection frequency of the H coil is about 40-100
Since the frequency is about kHz, the connection circuit uses an inductance as a current adjusting element. This is because the V coil uses a variable resistor, whereas the H coil has a high frequency, so that using an inductance makes it easier to change the current. The blocks 13a1 and 13a2 are connected in parallel, and have a variable inductance Lva for adjusting the current balance between 13a1 and 13a2. Similarly, variable inductances Lvb, Lvc are connected to the blocks 13b1, 13b2 and 13c1, 13c2. Further, the entire circuit is configured using the inductances L1, Lv2, Lv3. The inductances Lv2 and Lv3 are variable. By adjusting Lv2 and Lv3, the ratio of the current flowing through each coil block can be adjusted.

As described above, the coil block division from the magnetic pole side to the split surface side is performed for each of the V coil and the H coil. By adjusting the ratio of the current flowing through each coil block, it is possible to change the barrel shape of the vertical deflection magnetic field for the V coil and change the pincushion shape of the horizontal deflection magnetic field for the H coil to adjust the misconvergence. I can do it. By adjusting the current of each of the coil blocks of the V coil and the H coil in this way, the misconvergence characteristics can be optimized.

FIG. 12 is a flowchart for adjusting the current value of each coil block to reduce misconvergence at each point on the screen. FIG. 12 will be described in order. First, the current of each coil block i of the V and H coils of the deflection yoke is set to Xi, and misconvergence at this time is obtained. Let Mpo be the misconvergence at the point p on the screen. Here Misconvergence M
The po is obtained from the magnetic field analysis and the beam trajectory analysis by numerical calculation at the design stage. At the prototype stage, it is determined from actual measurements. Next, the amount of change in the value of each misconvergence when the value of each current Xi is slightly changed is determined. Since the amount of change in misconvergence at the point p depends on the amount of change in each current Xi, if the amount of change in misconvergence at the point p corresponding to each Xi is Mpi, then Mp = Mpo +
ΣMpi (Xi). Here, the sum symbol is for i. Thus, the misconvergence Mp at each point is represented by a function of each Xi. In order to reduce the misconvergence, the sum of the squares of the misconvergence Mp at each point is taken as an objective function, and each Xi that minimizes the objective function is obtained. The current value Xi of each coil block is obtained by a well-known method, for example, by the quasi-Newton method. By repeating this procedure as necessary, a suitable current value Xi can be determined. Thus, a deflection yoke for a color cathode ray tube having excellent misconvergence characteristics can be provided.

Here, the effectiveness of optimizing the misconvergence characteristic using the deflection yoke of the V and H coils divided into a plurality of coil blocks according to the present invention will be described. The positions of the misconvergence of interest are the points R1 to R5 and B1 to B4 in the first quadrant in FIG. 8 in consideration of the symmetry of the graphic on the screen. In order to optimize the misconvergence characteristics of these points, a model in which the V coil is divided into three coil blocks and the H coil is divided into five coil blocks is used here. In addition, as shown in FIG. 7, the current of the coil 4b at the horizontal position and the current of the coil 4c at the oblique position are considered for CY. For the first misconvergence before optimization, FIG.

[0018]

[Table 1]

Table 1 shows a rectangular figure and values of misconvergence at each point. Here, a point on a rectangular figure is represented by a combination of I and J values. In Table 1, for the points I and J, the x and y coordinates of B and the x and y coordinates of R
It is represented by x, By, Rx, and Ry. Misconvergence is up to 2.07 mm. Figure 1 shows the DY model.
FIG. 14 and FIG. 14 show the results obtained by actually applying the current value optimization method shown in FIG.

[0020]

[Table 2]

The misconvergence shown in Table 2 is obtained. According to this result, the misconvergence is at most 0.1 mm
It is. As a result, the deflection yoke of the present invention, which has a structure in which a coil is divided into a plurality of coil blocks and different currents can be supplied to each coil block, has excellent misconvergence characteristics by an optimization method using each current value as a parameter. It can be seen that a deflection yoke can be provided.

The deflection yoke of the present invention is useful not only for designing an optimum winding distribution of a coil, but also for adjusting misconvergence caused by a winding error of a coil conductor generated when the coil is wound. is there. Conventionally, adjustment of misconvergence caused by winding errors has been dealt with by attaching a ferrite sheet to the coil surface of the deflection yoke. In the present invention, it is not necessary to stretch a ferrite sheet as in the related art, and by adjusting the variable resistance and the variable inductance using an optimization method, it is possible to cope with misconvergence caused by a winding error.

[0023]

According to the present invention, a color CRT with less misconvergence can be obtained by controlling the coil magnetic field with the current of each coil block.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a coil of a deflection yoke.

FIG. 2 is a sectional view of a coil of a vertical deflection yoke.

FIG. 3 is an electric circuit diagram of a coil.

FIG. 4 is a bird's-eye view of a deflection yoke.

FIG. 5 is a bird's-eye view of a vertical deflection coil.

FIG. 6 is a bird's-eye view of the horizontal deflection coil.

FIG. 7 is a configuration diagram of a convergence yoke.

FIG. 8 is a diagram of misconvergence on a screen.

FIG. 9 is a circuit diagram of a vertical deflection yoke including CY.

FIG. 10 is a sectional view of a coil of a horizontal deflection yoke.

FIG. 11 is an electric circuit diagram of a horizontal deflection yoke.

FIG. 12 is a flowchart for calculating a current value of a coil block.

FIG. 13 is a diagram of misconvergence on a screen.

FIG. 14 is a diagram of misconvergence on a screen.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vertical deflection coil (V coil), 2 ... Horizontal deflection coil (H coil), 3 ... Core, 4 ... Convergence yoke (CY), 10 ... Deflection coil comprised of the coil block of this invention, 10a1, 10a2, 10b1,10b
2, 10c1, 10c2 ... Coil blocks constituting the vertical deflection coil of the present invention, 13a1, 13a2, 13b1,
13b2, 13c1, 13c2 ... Coil blocks constituting the horizontal deflection coil of the present invention.

Claims (1)

[Claims] 1. A deflection yoke formed of a plurality of coil blocks in which a plurality of saddle-shaped coils used for an in-line type color display device are bundled, wherein at least one of the plurality of coil blocks is provided. A deflection yoke characterized in that a current different from other coil blocks can be supplied.