JPH0461457B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a deflection yoke device for a color picture tube device having an in-line electron gun.

[Technical background of the invention]

Important characteristics of the deflection yoke of a color picture tube device include beam convergence and raster distortion characteristics.

In a color picture tube with an in-line electron gun, the horizontal deflection magnetic field is used as a pincushion magnetic field, and the vertical deflection magnetic field is used as a barrel magnetic field, thereby concentrating both side beams among the three electron beams on the same plane. It is designed to. Further, the concentration of the side beams and the center beam is performed by a magnetic field control element attached to the tip of the electron gun.

On the other hand, when using the above magnetic field shape, the raster distortion characteristics are such that distortion in the vertical direction of the screen is improved, but
The distortion in the left-right direction tends to increase the pink tension shape. This increase in left and right pink tension distortion is
This is caused by changing the vertical deflection magnetic field to a barrel magnetic field. In order to improve this, the vertical deflection magnetic field must be made into a pink tension magnetic field.

To solve this difficulty, we take advantage of the property that raster distortion largely depends on the magnetic field on the front side of the deflection magnetic field, that is, the fluorescent surface side, and make the front side magnetic field a pink tension type, so that the magnetic field on the neck side, that is, the electron gun side, is It has been proposed to improve beam concentration and raster distortion by creating a strong barrel shape and an overall barrel shape.

Figures 1 and 2 show an example of a deflection yoke device as shown in Japanese Utility Model Publication No. 58-38521.
is wound, and a saddle-shaped horizontal deflection coil 1 is located inside it. In order to achieve both the above-mentioned beam concentration and improvement of raster distortion, a pair of magnetic pieces 4 are attached vertically symmetrically inside the vertical deflection coil as a method of forming the vertical deflection magnetic field on the neck side into a strong barrel magnetic field. .

[Problems of Background Art] By the way, the magnetic piece 4 has the following drawbacks.

The positional relationship between the horizontal deflection magnetic field 5 and the magnetic piece 4 is as follows.
In the figure, the hysteresis curve 12 of the magnetic piece 4 is as shown in FIG. In FIG. 4, point 9 shows a state where the light is deflected to the left end of the screen, and point 10 shows a state where the light is deflected to the right end of the screen. Further, the material used for the magnetic piece 4 (silicon steel plate, etc.) has a small coercive force and its magnetization is saturated in a normal deflection magnetic field. As the magnetic piece 4 is horizontally deflected, the magnetic flux density B inside the magnetic piece 4 passes from point 9 to point 11 to point 10.
Draw the curve shown by the solid line leading to . Therefore, residual magnetization remains at the point 11 where the horizontal deflection magnetic field 5 becomes zero.
The dotted line indicates the retrace period.

This residual magnetization creates a magnetic field 13 that extends to the positions of the three electron beams 6, 7, and 8, as shown in FIG. This magnetic field 13 affects the center beam 7 and the side beams 6 and 8, but if the magnetic piece 4 is adjusted so that the vertical deflection magnetic field on the neck side becomes a strong balul magnetic field, the magnetic field near the orbit of the center beam 7 becomes larger than the magnetic field near the orbits of the side beams 6 and 8, and the force applied to the center beam 7 becomes larger. For this reason, the center beam 7 is more important than the side beams 6 and 8.
It is largely deflected to the left side of the screen. Therefore, even if the three beams are concentrated around the screen, a concentration error occurs between the side beams 6 and 8 and the center beam 7 at the center of the screen, as shown in FIG. If the 6-pole magnet attached to the neck is adjusted so that the 3 beams are concentrated at the center of the screen, the 7th
As shown in the figure, concentration errors occur around the screen. Such concentration errors cannot be corrected by the deflection yoke magnetic field. In addition, the magnitude of this concentration error is 0.1 to 0.3 mm in a normal color picture tube, which significantly degrades the screen quality and is a big problem for the realization of display tubes and color picture tubes with even higher resolution. It is becoming.

[Purpose of the invention]

An object of the present invention is to provide a deflection yoke device capable of correcting the concentration error of the center beam and side beams at the center of the screen.

[Summary of the invention]

The present invention comprises a deflection yoke device having a pair of magnetic pieces and a pair of permanent magnets that are vertically symmetrically attached inside a vertical deflection coil used in an in-line color picture tube, and the magnetic pole of the permanent magnet piece is connected to the vertical deflection coil. By setting the N pole (anode) on the side and the S pole (cathode) on the tube axis side, the residual magnetization of the magnetic piece at the center of the screen is canceled out, thereby eliminating the concentration error between the center beam and the side beam. .

[Embodiments of the invention]

Embodiments of the present invention will be described using the drawings. 8th
Figures a and b show an embodiment of the invention.

In FIG. 8, a pair of magnetic pieces 4 are attached to vertically symmetrical positions inside a vertical deflection coil (not shown), and a permanent magnet piece 14 is placed in contact with the outside of each of these two magnetic pieces 4. has been done. These permanent magnet pieces 14 are both magnetized so that the upper side, that is, the vertical deflection coil side, is the north pole, and the lower side, that is, the tube axis side, is the south pole. Therefore, the magnetic field 15 of the permanent magnet piece 14 acts in a direction to cancel the residual magnetization caused by the horizontal deflection magnetic field of the magnetic piece 4 at the center of the screen. Therefore, by adjusting the magnetization strength of the permanent magnet piece 14, the residual magnetization of the magnetic piece 4 can be made zero.

FIG. 9 shows a hysteresis curve 16 of the magnetic piece 4 when correction is performed using the permanent magnet piece 14. As the hysteresis curve 16 in FIG. 9 is horizontally deflected, the magnetic flux density B of the magnetic piece 4 forms a solid line from point 9 indicating the left edge of the screen, through point 11 indicating the center of the screen, to point 10 indicating the right edge. and the retrace period is indicated by a dotted line. During the horizontal deflection period, the residual magnetization at the center of the screen becomes zero, and therefore there is no magnetic field contributing to beam deflection due to the residual magnetization of the magnetic piece 4. Therefore, the concentration error between the center beam 7 and the side beams 6 and 8 at the center of the screen can be eliminated. As is clear from FIG. 9, the peripheral area of the screen is the same as the case without the permanent magnet piece 14, and does not have any influence. That is, according to this embodiment, only the concentration error of the center beam 7 and the side beams 6 and 8 near the center of the screen can be eliminated. Additionally, although the beam is deflected by the permanent magnet piece mentioned above, it has almost no effect on vertical deflection due to the direction of the magnetic field, while for horizontal deflection the magnetic field remains the same across the entire screen. Therefore, if you adjust the beam so that it is concentrated at the center of the screen, the beam will be concentrated over the entire screen and will not affect the screen quality.

FIG. 10 shows another embodiment of the invention. In FIG. 10, the permanent magnet piece 17 is placed in contact with the inside of the magnetic piece 4. Even in this case, if the upper side of the permanent magnet piece 17 is magnetized with the north pole and the lower side with the south pole, the magnetic field will have the hysteresis characteristic 16 in FIG. 9, and the residual magnetization of the magnetic piece 4 at the center of the screen will be Can be canceled out. Therefore, the same effect as shown in FIG. 8 can be obtained.

FIG. 11 shows still another embodiment of the present invention. In the embodiment of FIG. 11, the permanent magnet piece 1
4 and 17 are arranged with the magnetic piece 4 in between.
In this case as well, the upper side of the permanent magnet pieces 14 and 17 is N
If the lower side of the pole is magnetized to the S pole, the residual magnetization of the magnetic piece 4 can be canceled out more effectively than in the cases shown in FIGS. 8 and 9. In this way, it is more effective if one or more permanent magnet pieces are arranged for one magnetic piece.

Further, in the embodiment shown in FIG. 8, the permanent magnet piece 14
Although the length of the permanent magnet piece 14 and the length of the magnetic piece 4 are shown to be the same, it is not necessarily necessary that the length and shape of the permanent magnet piece 14 be the same as that of the magnetic piece 4.

〔Effect of the invention〕

As described above, according to the present invention, a magnetic piece and a permanent magnet piece are provided inside the vertical deflection coil, and by canceling the residual magnetization at the center of the screen due to the horizontal deflection magnetic field of the magnetic piece, the magnetic field due to the residual magnetization is eliminated. It is possible to eliminate the concentration error between the center beam and side beams. Further, at this time, the peripheral area of the screen is not affected in any way. Therefore, the beam concentration characteristics over the entire screen can be improved, and the screen quality can be improved.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view showing an example of a semi-toroidal deflection yoke device, Fig. 2 is a sectional view seen from the tube axis side of Fig. 1, and Fig. 3 is the position of the conventional magnetic piece and horizontal deflection magnetic field. Figure 4 is a characteristic diagram showing the hysteresis curve of a conventional magnetic piece. Figure 5 is a cross-sectional view showing the magnetic field distribution due to residual magnetization of a conventional magnetic piece. Figure 6 is a characteristic diagram showing the hysteresis curve of a conventional magnetic piece. Figure 7 is a front view showing the concentration error of the center beam and side beams on the screen. Figure 7 is a front view showing the concentration error when the center beam and side beams are combined at the center of the screen in Figure 6. Figure 8a is a front view showing the concentration error when the center beam and side beams are combined at the center of the screen. A sectional view for explaining one embodiment of the present invention, FIG. 8b is an enlarged view of the main part of FIG. 8a,
9 is a characteristic diagram showing the hysteresis curve of the embodiment of FIG. 8, FIGS. 10a and 11a are sectional views showing other embodiments of the present invention, and FIGS. 10b and 11 are
Figure b is an enlarged view showing the main parts of Figures 10a and 11a, respectively. 1... Horizontal deflection coil, 2... Vertical deflection coil, 3... Annular core, 4... Magnetic piece, 5... Magnetic field, 6, 8... Side beam, 7... Center beam, 9, 10, 11 ... Point, 12 ... Hysteresis curve, 13 ... Magnetic field, 14 ... Permanent magnet piece, 1
5...Magnetic field, 16...Hysteresis curve, 17...
...Permanent magnet pieces, 18, 19...Magnetic field.

Claims (1)

[Claims] 1. In a color picture tube deflection yoke device having an in-line electron gun formed by combining a pair of vertical deflection coils and a pair of horizontal deflection coils symmetrically about the tube axis, the pair of vertical deflection coils correspond to the pair of vertical deflection coils. A pair of magnetic pieces and a pair of permanent magnet pieces are arranged on the tube axis side of the deflection coil, and the pair of permanent magnet pieces are magnetized so that the vertical deflection coil side is magnetized as an N pole and the tube axis side is magnetized as an S pole. A deflection yoke device featuring: