JPH06267457A - Cathode-ray tube device - Google Patents

Abstract

PURPOSE:To realize improvement of deflection sensitivity of a deflection yoke and correction of comatic aberration (VCR) with simple constitution. CONSTITUTION:Circular arc shape magnetic pieces 14 opposing to each other with a vertical axis between them via an insulator are arranged outside of a crossover part 15 of neck side of horizontal deflection coil 11. Accordingly, a horizontal deflecting magnetic field is intensified by the magnetic pieces 14 and a pin cushion shape magnetic field is formed in the neck of electron gun side so as to correct comatic aberration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube (hereinafter referred to as "CR" such as a display monitor or a television receiver).
The device referred to as "T"), and more particularly, to a deflection yoke used in the device.

[0002]

2. Description of the Related Art In recent years, deflection yokes used in CRT display devices are required to have higher quality characteristics. One of the conditions required for such a deflection yoke is to be able to reproduce the winding distribution of the coil at the time of manufacture with the winding distribution as originally designed.

As a deflection coil winding method for this purpose, there is a slit saddle winding method in which a conductor is directly wound on a saddle type coil bobbin provided with a guide groove for the coil conductor.

As shown in FIG. 15, the inner surface of a saddle-shaped coil bobbin 1 is provided with a plurality of wire guide grooves 2 extending in the axial direction of the bobbin, the screen-side folded-back portion 3 of the coil bobbin 1, and the neck side. A plurality of winding hooks 5 and 6 are provided on each of the folded-back portions 4 for guiding the conductor wire in a folded manner, and the conductor wire is wound in a saddle shape along each conductor wire guide groove of the coil bobbin 1 to form a coil. .

Japanese Patent Laid-Open No. 14404/1992, which uses this slit saddle winding method and further considers the assemblability.
No. 2 and Japanese Patent Laid-Open No. 147546/1989, the outer diameters of the upper and lower horizontal deflection coil neck side folded portions are wound on an integral type coil bobbin set to be smaller than the inner diameter of the core, and the non-divided type There is an integrated slit saddle winding method that allows the core to be assembled in the axial direction of the bobbin. FIG. 16 is a diagram showing an example of this slit saddle winding system.

[0006]

The above-mentioned integrated slit saddle winding method has the effects of improving the winding accuracy and rationalizing the assembling work (it is easy to cope with automatic assembly), but has the following drawbacks. To have.

First, in the bobbin structure shown in FIGS. 16 (a) and 16 (b), the outer diameter is suppressed to a small value by forming the one-step folded-back portion shown in FIG. 15 into a multi-step structure.
The outer diameter of the folded-back portion is larger than the outer diameter of the trumpet-shaped tapered portion by the thickness of the folded wire, and in order to insert the core in the bobbin axial direction, it is necessary to make the inner diameter of the core larger than before. There is.

However, increasing the inner diameter of the core means that
This means that the magnetic resistance viewed from the deflection coil becomes large and the efficiency of generating the deflection magnetic field becomes poor, so that the deflection sensitivity of the deflection yoke deteriorates and the power consumption of the deflection circuit increases. This is a serious problem in a television with wide-angle deflection and an HDTV / high-resolution display monitor that performs high-speed scanning.

Further, in the self-convergence type deflection yoke, the vertical deflection magnetic field is a barrel type magnetic field, but due to this influence, coma aberration (VCR) as shown in FIG. 17 occurs. Conventionally, an auxiliary coil 7 as shown in FIG. 18 is provided on the electron gun side, and a pincushion type magnetic field 9 shown in FIG. 19A is formed in the CRT neck 8 to generate an electron beam 10 as shown in FIG. 19B. Was corrected to correct the coma aberration, resulting in an increase in cost.

The present invention has been made for the purpose of solving the above problems, and an object thereof is to obtain a cathode ray tube device having an integrated slit saddle winding type deflection yoke having a high vertical deflection sensitivity.

Another object of the present invention is to correct the coma aberration generated by the barrel-shaped vertical deflection magnetic field of the self-convergence deflection yoke at low cost.

[0012]

In the cathode ray tube device according to the present invention, an arcuate magnetic piece is formed on the outer side of the neck portion of a horizontal deflection coil arranged to extend along the outer peripheral surface of the cathode ray tube to the neck portion. Is arranged.

Further, a pair of arcuate magnetic pieces are arranged so as to face each other with the vertical axis of the cathode ray tube interposed therebetween.

Further, the arc-shaped magnetic piece is made of a ferrite material.

A plurality of slit grooves parallel to the arc-shaped magnetic piece are formed.

The circumferential length of the arc-shaped magnetic piece at the end on the electron gun side is longer than the circumferential length at the end on the screen side.

Further, a cutout extending in the tube axis direction is provided in a portion of the end of the arc-shaped magnetic piece on the electron gun side through which the horizontal axis passes.

Further, at the end of the arc-shaped magnetic piece on the electron gun side,
A semi-annular folded-back portion is provided in a direction approaching the tube axis.

Further, at the end of the arc-shaped magnetic piece on the electron gun side,
A semi-annular folded portion is provided in a direction approaching the tube axis, and a notch is provided in a portion sandwiching the horizontal axis.

Further, a folding portion is provided at the end of the arc-shaped magnetic piece on the screen side in the direction away from the tube axis.

Further, a semi-circular folded portion is provided at the end of the arc-shaped magnetic piece on the screen side in a direction away from the tube axis, and the circumferential length thereof is determined from the circumferential length of the arc-shaped magnetic piece. Is also a long one.

Further, a turn-back portion is provided at the end of the arc-shaped magnetic piece on the screen side in a direction away from the tube axis, and a winding is provided in the turn-back portion to which a current synchronized with the vertical deflection frequency is passed. Is.

Further, the arc-shaped magnetic piece is formed of a ferrite material, and a semicircular magnetic piece whose inner peripheral end faces the tube axis is provided at the end portion on the electron gun side.

Further, another arc-shaped magnetic piece is provided near the center of the deflection yoke.

Further, the vicinity of the horizontal axis of the cathode ray tube of the cylindrical core arranged on the outer periphery of the horizontal deflection coil is extended to the electron gun side to form an extension portion, and the extension portion has a semi-circular magnetic piece. Is provided.

[0026]

[Function] The arc-shaped magnetic pieces, which are arranged outside the crossing portion of the horizontal deflection coil so as to face each other across the vertical axis via the insulator, strengthen the horizontal deflection magnetic field generated by the vertical deflection coil. At the same time, a pincushion type magnetic field is generated by the vertical deflection leakage magnetic flux collected on the electron gun side.

When the arc-shaped magnetic piece is made of a ferrite material, the high frequency loss of the magnetic piece is reduced.

Further, when the slit-shaped groove is provided in the arc-shaped magnetic piece, the eddy current loss generated in the magnetic piece by the horizontal deflection magnetic field is reduced.

If the circumferential length of the end of the arc-shaped magnetic piece on the side of the electron gun is made longer than the circumferential length of the end on the side of the screen, it becomes easier to collect the leakage magnetic field of the vertical deflection coil, and the side of the electron gun becomes easier. The pincushion type magnetic field formed at the end portion becomes strong.

If a notch is provided at the end of the arc-shaped magnetic piece on the side of the electron gun that sandwiches the horizontal axis, the pincushion-type magnetic field formed at the end of the magnetic piece on the side of the electron gun becomes stronger.

Further, when the folded portion is provided at the end of the arc-shaped magnetic piece on the electron gun side in the direction of approaching the tube axis, the distance between the left and right magnetic pieces becomes short, and the magnetic resistance of this portion decreases. The pincushion type magnetic field that is formed becomes stronger.

Further, by forming a fold-back portion in the direction close to the tube axis at the end of the arc-shaped magnetic piece on the electron gun side, and providing a notch near the horizontal axis of the fold-back portion, the center beam and the side beam are formed. A pincushion-type magnetic field with a difference in sensitivity is formed.

Further, if the arc-shaped magnetic piece is provided with a fold back in a direction away from the tube axis on the screen side end, it becomes easy to collect the leakage magnetic flux from the vertical deflection coil, the vertical deflection sensitivity is improved, and the electron gun is improved. The pincushion type magnetic field formed on the side becomes stronger.

Further, a folding portion is provided at the end of the arc-shaped magnetic piece on the screen side in a direction away from the tube axis, and the circumferential length of this folding surface is longer than the circumferential length of the arc-shaped portion of the magnetic piece. Therefore, the vertical deflection leakage magnetic flux is more easily collected, the vertical deflection sensitivity is greatly improved, and the pincushion type magnetic field formed on the electron gun side is strengthened.

Further, since a turnback portion is provided at the end of the arc-shaped magnetic piece on the screen side in the direction away from the tube axis, and a winding through which a current synchronized with the vertical deflection frequency flows is provided at this turnback portion, a vertical deflection magnetic field is obtained. Is increased, the pincushion type magnetic field formed on the electron gun side is also increased. The strength of the magnetic field can be finely adjusted by adjusting the number of turns of this winding.

Further, since a ferrite material is used for the arc-shaped magnetic piece, high frequency loss can be suppressed, and since the semi-annular magnetic piece is provided at the electron gun side end of this ferrite magnetic piece, a pin cushion type A magnetic field can be created.

Further, if another arc-shaped magnetic piece is provided inside the vertical deflection coil, the magnetic flux generated by the vertical deflection coil passes through the another arc-shaped magnetic piece having a low magnetic resistance and the central portion of the deflection yoke. The barrel shape of the vertical deflection magnetic field in the vicinity is strengthened. Therefore, it is possible to cancel the misconvergence amount due to the pincushion-shaped magnetic field that becomes stronger on the electron gun side of the arcuate magnetic piece, and it is possible to realize the self-convergence function.

Further, the extension portion provided near the horizontal axis of the cylindrical core is a pin cushion type which is formed on the electron gun side by efficiently guiding the vertical deflection magnetic flux to the magnetic piece installed on the tip portion of the electron gun side. Strengthen the magnetic field.

[0039]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is an external view of the first embodiment. In the figure, 1
1 is a horizontal deflection coil, 12 is a separator that is an insulator covering the horizontal deflection coil 11, 13 is a cylindrical ferrite core, 14 is a pair of arc-shaped magnetic pieces that face each other across a horizontal axis, and are made of silicon steel sheet. And the horizontal deflection coil 1
It is attached to the outside of the crossover portion 15 on the neck side of No. 1 so as to face each other with the vertical axis interposed therebetween with the separator 12 interposed therebetween.

FIG. 2 is a sectional view of a portion including the magnetic piece attached to the neck side of the deflection yoke, taken along a line perpendicular to the tube axis.
FIG. 3 is a sectional view of a portion to which the magnetic piece is not attached. 2 and 3, 16 is a horizontal deflection magnetic field for deflecting the electron beam emitted from the electron gun of the CRT, and FIG.
Comparing (a) with the horizontal deflection magnetic field 16 in FIG. 3, the horizontal deflection magnetic field 16 in FIG. 2 is magnetized by the magnetic field generated by the horizontal deflection coil 11 in the arc-shaped magnetic piece 14 and has the same direction as the horizontal deflection magnetic field. Since a magnetic field is generated, it becomes stronger than in FIG. 3, and this magnetic field acts in the direction of increasing the deflection amount of the electron beam, so that the horizontal deflection sensitivity of the deflection yoke is improved.

The arc-shaped magnetic piece 14 collects the leakage magnetic flux of the vertical deflection magnetic field generated by a vertical deflection coil (not shown), and the leakage magnetic flux of the vertical deflection magnetic field is shown in the neck on the electron gun end side as shown in FIG. 2 (b). Since a pincushion-shaped vertical deflection magnetic field 9 is generated, coma can be corrected.

Although the barrel-shaped magnetic field as the total amount of the vertical deflection magnetic field is weakened by the formation of this pincushion-shaped magnetic field 9, if the barrel shape of the horizontal deflection magnetic field by the horizontal deflection coil is strengthened accordingly, The self-convergence function is not impaired.

Example 2. The magnetic piece 14 of the second embodiment causes high frequency loss and heat generation due to a change in horizontal deflection magnetic field (change in scan). However, the magnetic piece is made of a ferrite material instead of a commonly used silicon steel sheet. Can be reduced.

Example 3. Arc-shaped magnetic piece 1 of the third embodiment
4 has the magnetic piece 14 by providing a plurality of parallel slit grooves 17 as shown in FIG. 4 (a) or FIG. 4 (b).
It is possible to reduce the overcurrent loss generated in the above and suppress heat generation.

Example 4. In the fourth embodiment, as shown in FIG. 5, by making the circumferential length of the arc-shaped magnetic piece 14 on the electron gun side longer than the length on the screen side, the pincushion shape of the magnetic field generated inside is reduced. It was made to strengthen.

Example 5. In the fifth embodiment, as shown in FIG. 6, a notch 18 is provided near the horizontal axis of the electron gun side end of the arc-shaped magnetic piece 14 so that the pincushion shape of the magnetic field formed in the neck is strengthened. It is the one.

Example 6. In the sixth embodiment, as shown in FIG. 7, an end portion of the arc-shaped magnetic piece 14 on the electron gun side is bent in the axial tube direction to form a semi-annular folded back portion 19, which is close to the electron beam. A pincushion-type magnetic field is formed on the to enhance the correction effect.

Example 7. In the seventh embodiment, as shown in FIG. 8, a notch 20 is formed in a portion sandwiching a horizontal axis of a semi-annular folded back 19 provided at an end of the arc-shaped magnetic piece 14 on the electron gun side.
Is provided so that the pincushion shape of the magnetic field formed near the electron beam becomes stronger.

Example 8. In the eighth embodiment, as shown in FIG. 9, an end portion of the arc-shaped magnetic piece 14 on the electron gun side is bent in a direction away from the shaft tube to form a folded portion 21, and the folded portion 21 is placed close to the core. The magnetic flux leaked from the vertical deflection coil is easily collected, and the strength of the pincushion type magnetic field formed in the neck is increased.

Example 9. In the ninth embodiment, as shown in FIG. 10, the circumferential length of the turnback 2 shown in the eighth embodiment is
The vertical deflection coil is formed by forming a semi-annular turnback 22 in the shape of a circular arc longer than the circumferential length of the circular arc-shaped magnetic piece so as to collect more leakage flux from the vertical deflection coil. Can be greatly improved, and the pincushion type magnetic field formed in the neck can be further strengthened.

Example 10. In the tenth embodiment, as shown in FIG. 11, a winding wire 23, through which a current synchronized with the vertical deflection frequency is passed, is provided at the folded portion 21 shown in the eighth embodiment, and the arc-shaped magnetic piece 14 is formed by this current. A horizontal deflection magnetic field is generated between them, and a pincushion type magnetic field is formed in the neck. Since the magnetic field strength can be easily adjusted by the number of turns of the winding wire 23, the degree of freedom in design is increased.

Example 11. The eleventh embodiment is a modification of the seventh embodiment, and as shown in FIG. 12, the arc-shaped portion of the magnetic piece 14 that generates a large amount of heat due to a change in the vertical deflection magnetic field is formed of a ferrite material or the like with a small high frequency loss. Then, a semi-annular magnetic piece 24 having a notch formed of a silicon steel plate is provided at the end of the magnetic piece 14 on the electron gun side in such a manner that the inner peripheral end surface thereof faces the tube axis. The heat generation can be reduced.

Example 12. In this embodiment, as shown in FIG. 13, they are opposed to each other on the inner side of a vertical deflection coil near the center of a deflection yoke (not shown) provided with an arcuate magnetic piece 14 with a horizontal axis in between. Since the second arc-shaped magnetic piece 25 is provided, it has the effect of strengthening the vertical deflection magnetic field to improve the deflection sensitivity and also the barrel shape of the vertical deflection magnetic field. Therefore, in the first to eleventh embodiments, the vertical deflection coil needs to be configured to generate a strong barrel-shaped magnetic field as described above in order to maintain the self-convergence function. However, according to the twelfth embodiment. For example, the second
This can be dealt with by adjusting the shape and position of the arc-shaped magnetic piece 25.

Example 13. In the thirteenth embodiment, as shown in FIG. 14, an extension portion 26 in which a portion of the cylindrical core 13 facing the horizontal axis is extended to the electron gun side is provided, and a semi-annular magnetism is formed on an end surface of the electron gun side. The piece 27 is installed,
The vertical deflection magnetic flux is passed through the extension 26 and the semicircular magnetic piece 2
7 to form a pincushion type magnetic field in the neck.

[0055]

Since the present invention is configured as described above, it has the following effects.

In the present invention, the arc-shaped magnetic pieces are provided outside the crossover of the horizontal deflection coil so as to face each other across the vertical axis via the insulator. Therefore, the horizontal deflection magnetic field is strengthened and the deflection yoke is formed. The horizontal deflection sensitivity of is improved.

Further, since the arc-shaped magnetic piece collects the horizontal deflection leakage magnetic flux and forms the pincushion type vertical deflection magnetic field in the neck on the side of the electron gun, the coma aberration can be corrected.

Since another arc-shaped magnetic piece is provided outside the arc-shaped magnetic piece and inside the vertical deflection coil near the center of the deflection yoke, the vertical deflection magnetic field is strengthened to improve the vertical deflection sensitivity. As the magnetic field is improved and a stronger barrel-shaped magnetic field is formed, the barrel shape of the vertical deflection magnetic field as a total amount can be restored by the arc-shaped magnetic piece provided on the neck side crossing portion of the vertical deflection coil. The convergence function can be maintained.

Further, the material and shape of the arc-shaped magnetic piece generate little heat, and the shape and shape of the vertical deflection leakage magnetic flux are easy to collect.
Since the pincushion-shaped magnetic field formed in the neck of the electron gun is formed to have a strong shape, the deflection sensitivity is good, the coma aberration (VCR) correction effect is obtained, and the deflection yoke having good convergence quality can be obtained at low cost. Is obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of a deflection yoke according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is a perspective view showing an arcuate magnetic piece according to a third embodiment of the present invention.

FIG. 5 is a perspective view showing an arcuate magnetic piece according to a fourth embodiment of the present invention.

FIG. 6 is a perspective view showing an arcuate magnetic piece according to a fifth embodiment of the present invention.

FIG. 7 is a perspective view showing an arcuate magnetic piece according to a sixth embodiment of the present invention.

FIG. 8 is a perspective view showing an arcuate magnetic piece according to a seventh embodiment of the present invention.

FIG. 9 is a perspective view showing an arcuate magnetic piece according to an eighth embodiment of the present invention.

FIG. 10 is a perspective view showing an arcuate magnetic piece according to a ninth embodiment of the present invention.

FIG. 11 is a perspective view showing an arcuate magnetic piece of Embodiment 10 of the present invention.

FIG. 12 is a perspective view showing an arcuate magnetic piece of Embodiment 11 of the present invention.

FIG. 13 is a perspective view showing an arcuate magnetic piece according to Embodiment 12 of the present invention.

FIG. 14 is a perspective view showing a cylindrical core according to a thirteenth embodiment of the present invention and a semi-annular magnetic piece disposed on the end face of the core on the electron gun side.

FIG. 15 is a view showing a coil bobbin of a conventional slit saddle winding system.

FIG. 16 is a view showing another example of a conventional integrated type saddle winding type coil bobbin.

FIG. 17 is a diagram showing a misconvergence pattern due to coma aberration (VCR).

FIG. 18 is a perspective view of a deflection yoke for performing coma correction using a conventional auxiliary coil.

FIG. 19 is a diagram showing the structure and operation of a conventional auxiliary coil.

[Explanation of symbols] 11 horizontal deflection coil 12 separator 13 cylindrical ferrite core 14 arcuate magnetic piece 15 crossing part on the neck side of the horizontal deflection coil 17 slit groove 18 cutout 19 semi-circular folding 20 cutout 21 folding 22 semi-annular turn back 23 winding 24 semi-annular magnetic piece 25 second annular magnetic piece 26 extension 27 semi-annular magnetic piece

[Procedure amendment]

[Submission date] January 10, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction content]

[0042] Note that the barrel-shaped magnetic field as a total amount of the vertical deflection magnetic field by the pincushion magnetic field 9 is formed is weakened, polarization direction magnetic field of the barrel Ru good <br/> in that much vertical deflection coil If the shape is strengthened, the self-convergence function is not impaired.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0051

[Correction method] Change

[Correction content]

Example 10. In the tenth embodiment, as shown in FIG. 11, a winding 23 to which a current synchronized with the vertical deflection frequency is applied is provided at the folded portion 21 shown in the eighth embodiment , and the vertical deflection magnetic field is also generated by this current. Raise and
A pincushion type magnetic field is formed on the lock side.
Since the magnetic field strength can be easily adjusted by the number of turns of the winding wire 23, the degree of freedom in design is increased.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0052

[Correction method] Change

[Correction content]

Example 11. The eleventh embodiment is a modification of the seventh embodiment, and as shown in FIG. 12, the arc-shaped portion of the magnetic piece 14 that generates a large amount of heat due to a change in the horizontal deflection magnetic field is formed of a ferrite material or the like with a small high frequency loss. Then, a semi-annular magnetic piece 24 having a notch formed of a silicon steel plate is provided at the end of the magnetic piece 14 on the electron gun side in such a manner that the inner peripheral end surface thereof faces the tube axis. The heat generation can be reduced.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0053

[Correction method] Change

[Correction content]

Example 12. In this embodiment, as shown in FIG. 13, they are opposed to each other on the inner side of a vertical deflection coil near the center of a deflection yoke (not shown) provided with an arcuate magnetic piece 14 with a horizontal axis in between. which was placed a second arc-shaped magnetic pieces 25, it has an action to enhance the barrel-shaped vertical deflection magnetic field. Therefore, in Examples 1 to 11,
In order to maintain the self-convergence function, the vertical deflection coil had to be configured to generate a strong barrel-shaped magnetic field as described above, but according to the twelfth embodiment, the second arc-shaped magnetic piece 25 is used. This can be dealt with by adjusting the shape and arrangement position of the.

Claims (14)

[Claims] 1. A cathode wire provided with a horizontal deflection coil extending along a peripheral portion of a cathode ray tube to a neck portion, and an arc-shaped magnetic piece arranged outside the neck portion side of the horizontal deflection coil. Tube device. 2. The cathode ray tube device according to claim 1, wherein a pair of arcuate magnetic pieces are arranged so as to face each other with a vertical axis of the cathode ray tube interposed therebetween. 3. The cathode ray tube device according to claim 1, wherein the arc-shaped magnetic piece is made of a ferrite material. 4. The cathode ray tube device according to claim 1, wherein the arc-shaped magnetic piece is formed with a plurality of parallel slit grooves. 5. The arc-shaped magnetic piece is formed in an arc shape in which the circumferential length of the electron gun side end of the cathode ray tube is longer than the circumferential length of the screen side end. Cathode ray tube device. 6. The cathode ray tube device according to claim 1, wherein the arc-shaped magnetic piece is provided with a notch extending in the tube axis direction at a portion through which the horizontal axis of the electron gun side end of the cathode ray tube passes. 7. The cathode ray tube device according to claim 1, wherein the arc-shaped magnetic piece is provided with a semi-circular folded portion at the end of the cathode ray tube on the electron gun side in a direction approaching the tube axis. 8. The arc-shaped magnetic piece is provided with a semi-circular folded portion at the end of the cathode ray tube on the electron gun side in a direction approaching the tube axis, and a notch is provided in a portion through which the horizontal axis of the cathode ray tube passes. The cathode ray tube device according to claim 1. 9. The cathode ray tube apparatus according to claim 1, wherein the arcuate magnetic piece is provided with a folded-back portion at a screen side end portion of the cathode ray tube in a direction away from the tube axis. 10. The arc-shaped magnetic piece is provided with a semi-circular folded portion at a screen side end of the cathode ray tube in a direction away from the tube axis, and a circumferential length of the arc-shaped magnetic piece is greater than a circumferential length of the magnetic piece. The cathode ray tube device according to claim 1, wherein the cathode ray tube device is formed in a long shape. 11. An arc-shaped magnetic piece is provided with a turnback portion in a direction away from the tube axis at an end of the cathode ray tube on the screen side, and the turnback portion is supplied with a current synchronized with a vertical deflection frequency. The cathode ray tube device according to claim 1, further comprising: 12. The arc-shaped magnetic piece is made of a ferrite material, and a semi-annular magnetic piece having an inner end surface facing the shaft tube is provided at an end of the cathode ray tube of the ferrite material on the electron gun side. The cathode ray tube device according to claim 1. 13. The cathode ray tube device according to claim 1, wherein another arc-shaped magnetic piece is provided near the center of the deflection yoke. 14. A horizontal deflection coil extending along the outer peripheral surface of the cathode ray tube to the neck portion, a cylindrical core disposed on the outer periphery of the horizontal deflection coil, and a horizontal direction of the cathode ray tube having the cylindrical core. A cathode ray tube device comprising an extension part extending near the axis toward the electron gun, and a semi-circular magnetic piece provided at the tip of the extension part.