JPH0482143A - Deflecting device for color image-receiving tube - Google Patents

Abstract

PURPOSE:To prevent the generation of mis-convergence of a side beam in its vertical direction on the horizontal axis of an image plane by installing a differential coil and a saturable reactor element in a region intercepted from a deflecting leaky magnetic-field. CONSTITUTION:In a horizontal deflecting coil 20, a first horizontal coil 20a and a second horizontal coil 20b are connected in parallel respectively to terminals H<+>, H<-> at horizontal output stages, and a first coil 22a and a second coil 22b both forming a differential coil 22 are further inserted in series respectively to these coils 20a, 20b so that a horizontal deflecting current flows through each of the terminals H<+>, H<->. Furthermore, a saturable reactor element 23 is inserted between the horizontal deflecting coil 20 and the differential coil 22. The coil 22 and the element 23 are respectively arranged near part of a core 19 between the large-diameter aperture plane 19a of the core 19 and the small-diameter aperture plane 19b thereof. The coil 22 on the other hand is composed of the coil 22a, and the coil 22b wound round the coil 22a so that their magnetic poles may face each other. This can prevent the generation of mis-convergence attendant upon magnetic coupling between a deflecting coil 18 and each of the differential coil 22 and the saturable reactor element 23.

Description

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

(Prior art) A color picture tube with an in-line type electron gun, in which three electron guns are arranged in-line, uses a horizontal deflection magnetic field as a binction magnetic field and a vertical deflection magnetic field as a barrel magnetic field. Since it is possible to obtain convergence of electron beams, it is widely used in display devices.

However, as higher definition is required for high-definition broadcasting and OA display, the deflection frequency becomes higher, and measures are needed to eliminate the on-screen deviation between the three electronic beams, which was previously invisible. Ta. That is, a saturable reactor element is inserted into the horizontal deflection circuit, the horizontal deflection magnetic field is modulated with vertical deflection synchronization, the cross-E convergence around the screen is corrected, and a pair of differential coils are inserted to correct the tube neck. Cross misconvergence Xv between the side beams Rb and Bb on the horizontal axis of the screen occurs because the windings and mounting of the horizontal deflection coils placed above and below the screen cause the deflection magnetic field to become asymmetric due to positional variations (Figure 7). is prevented.

However, these saturable reactor elements and differential coils are made by winding a coil around a rod-shaped core, and have a large leakage magnetic field and are susceptible to the influence of magnetic fields from other sources. A problem has arisen.

(Problems to be Solved by the Invention) Recent deflection yokes for color display tubes are mainly of the saddle-saddle type in which both the horizontal and vertical deflection coils are saddle-shaped and are surrounded by a ferrite core. A feature of this saddle-saddle type deflection yoke is that there is little external leakage magnetic field, and this is an effect of surrounding the deflection coil with a ferrite core.

If a saturable reactor element or differential coil is magnetically coupled with an external magnetic field, it will malfunction. The same is true when magnetically coupled with the magnetic flux from the deflection coil. In particular, in the differential coil, the inductance of the two coils changes due to the linkage of the external magnetic field, and as shown in Figure 7, the inductance of the two coils changes. As described above, the cross misconvergence Xv changes. In addition, problems also occur when the differential coil intersects with the leakage magnetic flux of the saturable reactor element. When the leakage magnetic field from the vertical coil of the saturable reactor element intersects with the differential coil, an induced voltage is generated in the first and second coils of the pair of differential coils, and this induced voltage causes the pair of parallel-connected An induced current flows between the horizontal deflection coils. This induced current generates a magnetic flux that affects the vertical deflection magnetic field. Since this magnetic flux gives an unbalanced electromagnetic force to the side beams Rb and Bb, misconvergence Yv, which is a vertical deviation of the side beams, remains at the top of the screen, which is the start of vertical deflection (FIG. 8).

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a core having a large-diameter aperture surface and a small-diameter aperture surface, a pair of horizontal deflection coils and a pair of vertical deflection coils disposed inside the core, respectively. a differential coil consisting of a first coil and a second coil that are connected in series to the horizontal deflection coil and have a common core, and a horizontal deflection current flowing through the horizontal deflection coil to a vertical deflection current of the vertical deflection coil. In the deflection device for a color picture tube, the first and second coils of the differential coil are configured such that their respective magnetic poles face each other, and the differential coil and the variable In the deflection device for a color picture tube, the saturation reactor element is disposed outside the core and between a large-diameter aperture surface and a small-diameter aperture surface of the core.

(Function) By installing the differential coil and the saturable reactor element in an area where the deflection leakage magnetic field is blocked by the cone-shaped core of the deflection yoke, magnetic coupling between these elements and the deflection leakage magnetic field is prevented. To prevent vertical misconvergence of side beams on the horizontal axis of the screen. In addition, the induced voltage generated in the differential coil due to magnetic coupling between the adjacent differential coil and the saturable reactor element is canceled by configuring the differential coil so that the magnetic poles created by the first and second coils face each other. This can prevent vertical misconvergence of side beams that occurs at the top of the screen.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

1 to 4 show one embodiment of the present invention.

In FIG. 2, the color picture tube device 10 includes a panel 11,
It has an envelope 14 consisting of a funnel 12 and a neck 13, and the envelope 14 includes a phosphor screen 15 on the inner surface of the panel 11 and a shadow mask 16 near the screen.
, an in-line electron gun 17 housed in the neck is arranged to form a color picture tube.

A deflection yoke 18 is attached to the outer periphery of the neck 13, and the three electron guns of the electron gun 17, that is, the electron gun Rg for red phosphor.
, the electron beams Rb, Gb, , Bb emitted from the line phosphor electron gun Gg and the blue phosphor electron gun Bg. The electron gun 17 is an in-line type electron gun, and is arranged in parallel in the horizontal scanning direction, with three electron beams arranged at equal intervals along the horizontal plane (direction of the paper in the figure) so as to converge the three electron beams near the center of the panel. Fire with. Here, the red electron beam Rb and the blue electron beam Bb are side beams, and the line electron beam Gb is a center beam.

As shown in FIG. 1, the deflection yoke 18 is of a saddle-saddle type, and each pair of saddle-type horizontal and vertical coils 20.2
1 are arranged to intersect at right angles, and the outside thereof is surrounded by a ferrite core 19.

FIG. 3 shows the circuit of the deflection yoke 18, in which the horizontal deflection coil 20 has a first horizontal coil 20a and a second horizontal coil 20b connected in parallel to terminals H and H of the horizontal output stage, and furthermore, a differential voltage is applied to each of these coils. First coil 22a of coil 22
and the second coil 22b are inserted in series, and the terminals H+ and H-
A horizontal deflection current flows through. Further, a saturable reactor element 23 is inserted between the horizontal deflection coil 20 and the differential coil 22, and the vertical deflection is synchronized via the vertical current coil 23d of the saturable reactor 23 connected in series to the vertical deflection coils 21a and 21b. The horizontal deflection current is corrected accordingly. Note that V+V indicates the terminal of the vertical output stage. As shown in FIG.
It is placed near the core between b.

As shown in FIG. 1, the saddle-saddle type deflection yoke 20 is surrounded on the outside by a deflection coil or core, so that leakage of the deflection magnetic field to the outside is small. In particular, the area A surrounded by the core 19 has weak leakage magnetic flux.

On the other hand, the differential coil 22, as shown in FIG. It has a structure in which a movable common core 22c is arranged, and the current in each branch of the horizontal deflection circuit connected in parallel is varied by differential inductance control of two coils.

This has the function of correcting vertical misconvergence of side beams that occurs on the horizontal axis of the screen. A differential coil having such a structure has a large amount of leakage magnetic field that affects the outside, and is easily influenced by leakage magnetic fields from the outside. Therefore, when the differential coil is installed in the rear crossover area B or the front crossover area C of the deflection yoke 18, the differential coil 22
The magnetic flux interlinks with the crossover section, causing an imbalance in the upper and lower inductances of the horizontal deflection coil 20, resulting in vertical misconvergence of the side beams Rb and Bb on the screen horizontal axis X as shown in FIG. It causes

However, in this embodiment, the differential coil 22 is arranged in the area A surrounded by the core 19 of the deflection yoke. This eliminates the linkage between the magnetic flux of the differential coil 22 and the crossover portion, and the above-mentioned problem is resolved. The position of the differential coil is preferably at the center of the back of the core where the deflection leakage flux is least, and according to experiments, a range of about 70% of the core length around the center of region A is most effective.

On the other hand, as shown in FIG. 5, the saturable reactor element 23 includes, as a typical example, two sets of structures 23e in which coils 23b are wound around two small ferrite pieces 23a in a direction that mutually cancels magnetic flux. , and the center core 23 is placed between them.
It has a structure in which a vertical current coil 23d wound around the coil 23d is inserted into the coil 23b, and the magnetic flux of the horizontal deflection current flowing through the coil 23b cancels out each other, so even if there is linkage with the deflection magnetic flux,
The effects are not as severe as with differential coils. However, since it is composed of a core and a coil, there is a considerable degree of magnetic coupling with the deflection magnetic field, so it is better to install it within the area A of the common core like the differential coil.

However, when the differential coil and the saturable reactor are installed in the core region A, these elements come close to each other, causing a problem of mutual magnetic coupling. Since recent display devices tend to have higher vertical deflection frequencies, the blanking period t1 of the vertical deflection current Iv shown in FIG. 9 becomes shorter. As a result, d i /d t of the erasing period t1 becomes large, and for example, the frequency during this period becomes equivalent to 15 kHz.

When the differential coil 22 and the saturable reactor element 23 are magnetically coupled, the vertical current coil 2 of the saturable reactor element 23
When the high frequency magnetic pole during the blanking period leaks from 3d, an induced current is generated in the differential coil 22. This induced current becomes noticeable when these elements are close to each other within 40 mm.

Here, the embodiment of the present invention (FIG. 3) will be compared with FIG. 6, which shows a conventional deflection circuit. In the differential coil 32 of the conventional example, the vertical current coil 33 of the saturable reactor element 33
Before the magnetic field Bz caused by
is generated in the second coil 33b. The directions of the voltages are opposite to each other as shown in the figure with the H terminal as a reference, so an induced current Ii flows in the parallel circuit of the horizontal deflection coils 20a and 20b.

On the other hand, in the embodiment, the winding direction of the second coil 22b is opposite to that of the first coil 22a, and the winding direction of the second coil 22b is opposite to that of the first coil 22a.
The second coil 23b has a structure in which magnetic poles are opposed to each other. Therefore, the induced voltage becomes a high voltage in the same direction at both ends of the coil with the H terminal as a reference, as shown in FIG. 3, val and vbl.

Therefore, the induced current that occurs in the conventional example does not occur. The influence when this induced current occurs will be explained with reference to FIG. 8th
The figure shows a cross section of the main deflection area of the horizontal deflection coils 20a and 20b.
FIG. The direction of the induced current 1i is marked with an OX mark. ○ indicates the direction from the back of the paper to the front, and × indicates the direction from the front of the paper to the back. The magnetic flux generated at this time becomes the magnetic flux indicated by Bh according to Lenz's law. The electromagnetic forces that side beams Rb and Bb receive due to this magnetic flux are Fl and F, respectively.
2, a vertical misconvergence Yv occurs as shown in FIG. 8 at the upper end of the screen where the influence of the flyback period occurs.

In this embodiment, since no such induced current is generated, this phenomenon does not occur.

[Effects of the Invention] As explained above in the embodiments, the deflection device of the present invention can prevent the occurrence of misconvergence due to magnetic coupling between the deflection coil, the differential coil, and the saturable reactor element. A deflection device for a color picture tube suitable for a high-definition display device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a deflection yoke according to an embodiment of the present invention;
2 is a sectional view showing a color picture tube equipped with the deflection yoke of FIG. 1, FIG. 3 is a circuit diagram of an embodiment of the present invention, and FIG.
The figure is a side view schematically showing the differential coil in Fig. 1, Fig. 5 is a front view schematically showing the saturable reactor element in Fig. 1, and Fig. 6 is a side view schematically showing the differential coil in Fig. 1.
The figure shows a circuit diagram of a conventional deflection yoke, Figure 7 is a plan view explaining cross misconvergence on the screen horizontal axis, and Figure 8
The figure is a plan view explaining misconvergence at the top of the screen.
FIG. 9 is a curve diagram showing the vertical deflection current waveform, and FIG. 10 is a cross-sectional diagram illustrating the occurrence of misconvergence. 10... Color picture tube, 18... Deflection yoke, 1
9... Core, 20... Horizontal deflection coil, 21... Vertical deflection coil, 22... Differential coil,
22a... common core, 22a... first coil,
22b...Second coil, 23...Saturable reactor element.

Claims (1)

[Claims] (1) A core having a large-diameter aperture surface and a small-diameter aperture surface, a pair of horizontal deflection coils and a pair of vertical deflection coils respectively arranged inside the core, and a common core connected in series to the horizontal deflection coils. and a saturable reactor element that changes the horizontal deflection current flowing through the horizontal deflection coil in accordance with the vertical deflection current of the vertical deflection coil. In the apparatus, the first and second coils of the differential coil are configured such that their respective magnetic poles face each other, and the differential coil and the saturable reactor element are located outside the core and have a large diameter of the core. A deflection device for a color picture tube, characterized in that it is arranged between an aperture surface and a small diameter aperture surface.