JPH0349132A - Deflection yoke - Google Patents

Abstract

PURPOSE:To concurrently remove positive and negative trilemmas by connecting a pair of auxiliary correcting coils to vertical coma-aberration correcting coils via nonlinear circuit elements. CONSTITUTION:A serial connection body consisting of nonlinear circuit elements 28 and auxiliary correcting coils 29 is connected in series with vertical coma- aberration correcting coils 25, vertical toroidal coils 26 and vertical saddle coils 27. Diodes 28a and 28b are kept off until the vertical deflecting voltage applied across terminals 30 and 31 becomes the preset value, and no trilemma of the center region of a fluorescent face occurs. When the absolute value of the vertical deflecting voltage exceeds the preset value, elements 28a and 28b are turned on, and a current flows through coils 29. The divergence quantity of the vertical deflection magnetic field to an electron gun side against the horizontal deflection magnetic field is quickly increased by the auxiliary magnetic field thus generated, the pin cushion distortion of the mating magnetic field distribution is weakened, and the occurrence of the negative trilemma in upper and lower regions of the fluorescent face is prevented. Positive and negative trilemmas can be concurrently removed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a deflection yoke mounted on a color picture tube incorporating an in-line electron gun.

Conventional technology The auxiliary magnetic field generation means for correcting misconvergence was installed at the small diameter opening end of the deflection yoke body (electron gun 1'1ll).
The deflection yoke arranged in
This is known from Publication No. 5, etc.

Problems to be Solved by the Invention However, in such a conventional deflection yoke, a central region (hereinafter referred to as A zone) that occupies approximately 1/2 of the vertical effective diameter of the phosphor screen and areas above and below it (hereinafter referred to as B zone) are・When a negative trilemma occurs, it cannot be corrected.

To explain the positive/negative trilemma with reference to FIG. 5, the red horizontal line 12R projected on the A zone of the fluorescent screen 11
and the blue # line 12B intersect on the vertical axis, and the blue horizontal line 1 is placed in the first and third quadrants of the fluorescent screen.
2B in the +y direction with respect to red'ftHl 2 R, and in the second and fourth quadrants, next to red, 11
2R is biased in the +y direction with respect to the blue Ii line 12B, and such misconvergence is called a positive trilemma. Also, the red horizontal line 13R projected in the B zone
And the blue one! The R line 13B intersects with the vertical axis and the red horizontal line 1 in the first and third quadrants of the fluorescent screen.
3R is deviated in the +y direction with respect to the blue horizontal line 13B, and in the second and fourth quadrants, the blue horizontal line 13B is deviated in the +y direction with respect to the red #l tightening 13R. Misconvergence is called a negative trilemma.

In addition, 52g.

r indicates the source of three electron beams for blue, green, and red.

Next, to explain the reason why such a positive/negative trilemma occurs, while direct current of an appropriate ratio is passed through the horizontal and vertical deflection coils, the probe 14 equipped with a Hall element is connected to the central axis of the deflection yoke as shown in FIG. 15 in a radial direction along a diagonal axis 16. When the magnetic field strength in the direction orthogonal to the diagonal axis 16 is measured, a diagonal magnetic field distribution 17, 18 having a curve as shown in FIG. 7 is obtained. Note that FIG. 6 is a view of the deflection yoke viewed from the large diameter opening end side (phosphor screen side), and the diagonal axis 16 is inclined at an angle of 35.6' with respect to the horizontal axis. Further, the position of the measurement point in the tube axis direction is slightly shifted from the center of the deflection yoke toward the large-diameter opening end, and generally, the magnetic field distribution at this position greatly affects the convergence characteristics.

Diagonal magnetic field distribution 17 near the deflection yoke central axis 15
is mainly involved in the generation of the trilemma in the A zone, and the magnetic field distribution 18 near the inner surface of the deflection yoke is mainly involved in the generation of the trilemma in the B zone.

When the diagonal magnetic field distribution 17.18 as shown in FIG. 6 is obtained, no trilemma occurs in the A zone and the B zone, and this diagonal magnetic field distribution 17.18 is the optimum diagonal magnetic field distribution as shown in the following explanation. That's what it means.

When the electron beam is deflected in the direction of the diagonal axis of the first quadrant of the phosphor screen, if the distortion of the magnetic field distribution near the deflection yoke center axis 15 has a barrel tendency with respect to the optimum diagonal magnetic field distribution 17, as shown in FIG. As shown, the difference between the Lorentz force 20 in the ±y force direction acting on the electron beam 19R for red light emission and the Lorentz force 21 in the +y force direction acting on the beam 19B for blue light emission is smaller than that of the optimal diagonal magnetic field distribution 17. (So, in the A zone of the first quadrant of the fluorescent screen, the blue side &*1
A positive trilemma occurs in which 2B deviates in the +y force direction with respect to the red horizontal line 12R. In addition, the distortion of the diagonal magnetic field distribution near the inner surface of the deflection yoke is the optimum diagonal magnetic field distribution 1
8, if there is a strong binction tendency, as shown in FIG.
Since the difference between the Lorentz force 24 in the direction of the +y force acting on the phosphor screen is larger than that of the optimal diagonal magnetic field distribution 18, the red horizontal line 13R is in the +y direction with respect to the blue horizontal line 13B in the B zone of the first quadrant of the fluorescent screen. A negative trilemma is generated that deviates in the direction of the force.

When the electron beam is deflected in diagonal directions in the second, third, and fourth quadrants of the phosphor screen, a positive trilemma is generated in the A zone and a negative trilemma is generated in the B zone for the same reason as described above. The following trilemmas occur.

Such a positive/negative trilemma will not occur if the horizontal deflection coil and vertical deflection coil are properly designed, that is, if they are formed so that an optimal diagonal magnetic field distribution is generated. Designing and manufacturing such a deflection yoke is extremely difficult.

Means for Solving the Problems In the present invention, a pair of vertical deflection coils connected to the vertical deflection coils are provided on the small diameter opening end side of a deflection yoke body comprising a pair of horizontal deflection coils and a pair of vertical deflection coils. A coma aberration correction coil and a pair of auxiliary correction coils connected to the coil via a nonlinear circuit element are provided.

The pair of coma aberration correction coils and auxiliary correction coils are arranged to face each other in the vertical direction, and a vertical deflection current having a cubic function waveform flows therethrough, while different patterns of the coma aberration correction coil and the auxiliary correction coil are applied in the A zone and the B zone. Since the force acts on the electron beam, it is possible to correct the positive and negative trilemmas. That is, when the electron beam is deflected in the A zone of the phosphor screen, the divergence Ik (difference between the vertical deflection magnetic field and the horizontal deflection magnetic field at the thin end of the electron gun) of the vertical deflection magnetic field to the electron gun control with respect to the horizontal deflection magnetic field is made small. It is possible to equivalently weaken the barrel distortion of the diagonal magnetic field. In addition, when deflecting the electron beam in the B zone of the phosphor screen, the amount of divergence of the vertical deflection magnetic field toward the electron gun side relative to the horizontal deflection magnetic field is increased (thus, equivalently, the vinctusion distortion of the diagonal magnetic field is weakened). Therefore, the positive and negative trilemmas occurring in the A zone and B zone of the phosphor screen can be removed at the same time.

Embodiment In FIG. 1 showing the circuit configuration of a deflection yoke embodying the present invention, a pair of vertical coma aberration correction coils 25, a pair of vertical toroidal coils 26, and a pair of vertical saddle coils 27 are shown.
, a nonlinear circuit element 28 and a pair of auxiliary correction coils 29
A series connection consisting of the nonlinear circuit element 28 and the auxiliary correction coil 29 is connected in parallel to the series connection body 30 and 31. However, the nonlinear circuit element 28 is composed of two diode elements 28a, 2 connected in parallel in opposite polarity directions.
8b, and each coil is combined with a pair of saddle-shaped horizontal deflection coils 33, etc., as shown in FIGS. 2 and 3. - Pair of vertical coma aberration correction coils 25
The pair of auxiliary correction coils 29 are wound around both legs of a pair of U-shaped magnetic cores 34a and 34b facing each other on the small diameter opening end side of the deflection yoke main body.

A vertical deflection voltage having a waveform as shown in FIG. 4(a) is applied between both terminals 30 and 31. The diode elements 28a, 28 until the absolute value of this voltage reaches a certain constant value VO.
b is almost in an off state, so almost no current flows through the pair of auxiliary correction coils 29. The ampere-turn ratio of the pair of vertical toroidal coils 26 and the pair of vertical saddle coils 27 is set to an appropriate value, and the amount of divergence of the vertical deflection magnetic field to the electron gun example with respect to the horizontal deflection magnetic field is reduced to equivalently diagonal. If the barrel distortion of the magnetic field distribution is weakened, trilemma will not occur in the A zone of the phosphor screen. When the absolute value of the vertical deflection voltage exceeds a certain value VO, the diode elements 28a and 28b are turned on, and the pair of A current flows through the auxiliary correction coil 29, and the auxiliary magnetic field generated thereby rapidly increases the amount of divergence of the vertical deflection magnetic field toward the electron gun side relative to the horizontal deflection magnetic field. Then, since the binction distortion of the diagonal magnetic field distribution is equivalently weakened, the B of the phosphor screen is
This can prevent the occurrence of negative trilemmas in the zone. In addition, the setting of the start time of the auxiliary correction coil 29 is as follows.
Since it is determined by the on-voltage characteristics of the diode elements 28a and 28b, the number of series connections of the same elements, the resistance value of the resistor element 32, etc., it goes without saying that these must be selected optimally.

In this embodiment, VO is set to 3. OV, by setting the ampere turns of the vertical toroidal coil to 130.7, the ampere turns of the vertical saddle coil to 55.4, and the ampere turns of the auxiliary correction coil to 48.0, the A zone and B zone of the phosphor screen The positive trilemma and negative trilemma that had previously occurred could be almost completely eliminated. Note that (b) and (c) in FIG. 4 show the vertical deflection current waveform and the waveform of the current flowing through the auxiliary correction coil.

In the above embodiment, two diode elements connected in parallel with opposite polarities were used as the nonlinear element, but a thyristor, a varistor, or the like may be used instead.

Furthermore, although we have described the so-called SST type deflection yoke in which the vertical deflection coil is configured by a toroidal type coil and a saddle type coil, the present invention provides a deflection yoke with a toroidal type vertical deflection coil and a saddle type horizontal deflection coil. It can also be applied to a so-called ST type deflection yoke that has a yoke main body. Furthermore, we have explained trilemma removal when a positive trilemma occurs in the A zone and a negative trilemma in the B zone of the phosphor screen. It is possible to deal with the cases where each trilemma occurs, the case where a positive or negative trilemma occurs only in the A zone, or the case where a positive or negative trilemma occurs only in the B zone.

Effects of the Invention Since the present invention is configured as described above, the vertical deflection magnetic field on the electron gun side with respect to the horizontal deflection magnetic field is By changing the amount of divergence, the distortion rate of the diagonal magnetic field distribution is equivalently changed, and it is possible to remove all patterns of trilemmas that occur in the A zone and B zone of the phosphor screen.

[Brief explanation of drawings]

Fig. 1 is a vertical deflection system circuit diagram of a deflection yoke embodying the present invention, Fig. 2 is a rear view of the deflection yoke viewed from the small diameter end, Fig. 3 is a side sectional view of the deflection yoke, and Fig. 4 Figure (a) ~
(c) is a voltage/current waveform diagram of the vertical deflection system circuit, Figure 5 is a diagram to explain the positive and negative trilemmas that occur in the A zone and B zone of the phosphor screen, and Figures 6 to 8 are This is to explain the cause of the trilemma. Figure 6 is a front view of the deflection yoke viewed from the large diameter end, Figure 7 is the optimum diagonal magnetic field indication, and Figure 8 shows the positive and negative trilemmas. FIG. 3 is a diagonal magnetic field distribution diagram when generated. 25... Vertical coma aberration correction coil, 26...
... Vertical toroidal coil, 27 ... Vertical saddle coil, 28 ... Nonlinear circuit element r129.
...Auxiliary correction coil, 32...Resistance element.

Claims (1)

[Claims] In a deflection yoke attached to a color picture tube with a built-in in-line electron gun, the vertical deflection coil is attached to the small-diameter opening end side of the deflection yoke body, which includes a pair of horizontal deflection coils and a pair of vertical deflection coils. A deflection yoke comprising a pair of connected vertical coma aberration correction coils and a pair of auxiliary correction coils connected to the coils via a nonlinear circuit element.