JPH04209449A - Cathode-ray tube device - Google Patents

Abstract

PURPOSE:To reduce leak of magnetic field by providing a magnetic body on external sides of front and rear flange parts of a vertical deflection coil and forming the magnetic body into ring or a rectangular shape. CONSTITUTION:A deflection yoke 26 is installed inside a separator 28 in vertical symmetry with a horizontal axis placed in its center and installed outside a saddle-shaped horizontal deflection coil 29 and a separator 28. The coils 29, 30 construct a front flange part A and a rear flange part B respectively. A conical tube-like core 33 is arranged on the external periphery of the coil 30. Ring magnetic bodies 27 are installed above and below the yoke 26, the screen sides and the electron gun sides of the ring magnetic bodies 27 are positioned near the flange part A and the flange part B, respectively. As the front and rear positions of each ring magnetic body are positioned respectively near the front and rear flange parts of a deflection yoke, the magnetic body is magnetized by the leaking magnetic field, so that compensation magnetic field in a direction reverse to that of the leaking magnetic field is generated.

Description

[Detailed description of the invention]

[Purpose of the invention] [00013

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube device that reduces leakage magnetic fields leaking to the outside of a deflection yoke. [0002] [0002] Recently, attention has been focused on the influence that leakage magnetic fields leaked from various devices have on the human body, mainly in Northern Europe, and there is a worldwide movement to regulate such leakage magnetic fields. The estimated value of this leakage magnetic field is Sweden's MPR (S
SI) standards have been established. With the revision of this standard, measures against leakage magnetic fields of 5 Hz to 400 kHz are required. Regarding cathode ray tube devices, efforts are being made to reduce the leakage magnetic field outside the magnetic field that contributes to the deflection of the electron beam, out of the magnetic field generated from the deflection yoke for deflecting and scanning the electron beam. According to the standard, it is necessary to reduce the leakage magnetic field generated from the horizontal deflection coil and the vertical deflection coil. Countermeasures against this leakage magnetic field include a compensation coil method in which a compensating magnetic field of the same magnitude is generated in the opposite direction to the leakage magnetic field in order to cancel the leakage magnetic field, and a method in which the entire cathode ray tube device is covered with a magnetic shielding member. [0003] Japanese Unexamined Patent Publication No. 62-64024 discloses FIG.
As shown in the figure, an auxiliary coil 3 having almost the same shape as the horizontal deflection coil 1 is arranged outside the saddle-shaped horizontal deflection coil 1 with the core 2 in between, and this has the direction of the main magnetic flux of the horizontal deflection coil shown by the arrow 4. A portion of the current flowing through the horizontal deflection coil 1 is caused to flow in opposite phase so that the magnetic flux indicated by the arrow 5 in the opposite direction passes through it.
The leakage magnetic field of the horizontal deflection coil 1 is reduced. but,
This method using the auxiliary coil 3 is difficult to control to reduce the leakage magnetic field at a predetermined position to a predetermined level.Furthermore, with the revision of the MPR standard mentioned above, it is necessary to compensate not only the leakage magnetic flux of the horizontal deflection magnetic field but also the leakage magnetic flux of the vertical deflection magnetic field. It is also necessary to newly install an auxiliary coil for this purpose, which poses problems such as a space for installing the auxiliary coil and an increase in power consumption. [0004] Furthermore, regarding the shield method, the display section on the front side of the cathode ray tube device cannot be shielded, and the effect against leakage magnetic fields on the front side of the cathode ray tube device is low. [0005] Furthermore, as an inexpensive and compact means different from the above method, Japanese Patent Application Laid-Open No. 64-45046 discloses
It is shown that a magnetically permeable ring is arranged between the screen and the deflection yoke as a magnetic shunting means to reduce the leakage magnetic field. As shown in FIG. 7, the cathode ray tube device disclosed in Japanese Patent Application Laid-Open No. 64-45046 has a relatively high magnetic permeability area adjacent to the front transition portion 6 of the saddle-shaped horizontal deflection coil 1 of the deflection yoke. , a linear ferrite ring 7 with high resistivity is installed. This linear ferrite ring 7 acts as a magnetic shunt means and reduces leakage magnetic field. [0006] However, in the structure shown in Japanese Unexamined Patent Application Publication No. 64-45046, the ring is installed in front of the deflection yoke, so there is a limit to the size of the ring. Also,
When attaching a deflection yoke to a cathode ray tube and adjusting its position (hereinafter referred to as ITC work), a wedge is inserted between the cathode ray tube and the deflection yoke to secure it. This makes ITC work difficult. Furthermore, in order to minimize the leakage magnetic field, it is necessary to make the inner diameter of the ring as small as possible so that it approaches the neck diameter of the cathode ray tube. Even with such a shape, there are problems in ITC work. In addition, the distance between the front end of the deflection yoke and the cathode ray tube is usually about 3 mm or less, but in order to minimize the leakage magnetic field, a thickness of at least several mm is required. It is necessary to change the design values such as YPB (Y.rk Pu1l Back) which determines the deflection center position of the device.
This also impairs the display characteristics of the cathode ray tube device, necessitating major changes in the design of the cathode ray tube device. [0007]

[Problems to be Solved by the Invention] Conventionally, measures to reduce leakage magnetic fields from cathode ray tube devices have been taken mainly for horizontal deflection magnetic fields, but recently, measures have been taken to reduce leakage magnetic fields from cathode ray tube devices.
(Extremely Low Frequency
The leakage magnetic field of 5H2-2k)Iz of ) is also attracting attention. [0008] As described above, in the method of using a compensation coil as a countermeasure against leakage magnetic field, there is a problem that it becomes difficult to attach the compensation coil when trying to reduce the leakage magnetic field due to the vertical deflection magnetic field. Furthermore, in a structure in which a magnetically permeable ring is arranged between the front end of the deflection yoke and the cathode ray tube, the I
This poses a problem in that the TC work becomes difficult, and furthermore, the display characteristics of the cathode ray tube device are significantly changed, making it necessary to change the design of the cathode ray tube device. [0009] In view of the above-mentioned problems, it is an object of the present invention to provide a cathode ray tube device that reduces leakage magnetic fields by simpler means. [00101 [Configuration of the invention] [0011]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a cathode ray tube that displays an image on a phosphor screen by scanning an electron beam emitted from an electron gun;
A horizontal deflection coil that is attached to the cathode ray tube and generates a horizontal deflection magnetic field that horizontally deflects the electron beam emitted from the electron gun, and a vertical deflection magnetic field that vertically deflects the electron beam emitted from the electron gun. The horizontal deflection coil includes a deflection yoke consisting of a pair of upper and lower saddle-shaped horizontal deflection coils, and an outer side of the deflection yoke and at least one side with respect to the plane of symmetry of the saddle-shaped horizontal deflection coil. a closed ring-shaped or rectangular magnetic body disposed in the deflection yoke, and the front side of the magnetic body on the screen side and the rear side on the electron gun side are positioned so as to cover the front flange part and the rear flange part of the deflection yoke, respectively. It is characterized by the fact that [0012]

[Operation] At least on one side with respect to the plane of symmetry of the saddle-shaped horizontal deflection coil of the deflection yoke, the screen-side front part and the electron gun-side rear part of the closed ring-shaped or rectangular magnetic material are attached to the front and rear flanges of the deflection yoke, respectively. By arranging the magnetic body so as to cover the area, the magnetic body is magnetized by the leakage magnetic flux and generates a compensation magnetic field in the opposite direction to the leakage magnetic field. Basically, by placing a magnetic body outside the front and rear flanges of the vertical deflection coil, the magnetic body is magnetized by the leakage magnetic field.
Generates a compensation magnetic field in the opposite direction to the leakage magnetic field. However, simply placing magnetic bodies outside the front and rear flanges of the vertical deflection coil produces a weak compensation magnetic field, so by connecting the front and back of the magnetic body to form a closed ring or rectangular shape, the volume of the magnetic body is increased and compensation is achieved. Strengthen the magnetic field. [0013]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. [00143] FIG. 1 shows a vertical sectional view of a cathode ray tube device that is an embodiment of the present invention. The cathode ray tube in this device has an envelope consisting of a substantially rectangular panel 20 and a funnel-shaped funnel 21 that are joined together, and on the inner surface of the panel 20 are three colors emitting light in red, green, and blue. A phosphor screen 22 made of a phosphor layer is provided, and a shadow mask 23 in which a large number of electron beam transmission holes are formed is mounted closely facing the phosphor screen 22. Also,
An electron gun 25 that emits three electron beams is disposed within the neck 24 of the funnel 21. More Funnel 21
A deflection yoke 26 that generates a magnetic field that deflects the electron beam emitted from the electron gun 25 in horizontal and vertical directions is mounted outside the boundary between the cone and the neck 24. There are ring-shaped magnetic bodies 2 above and below this deflection yoke.
7 is placed. [0015] FIG. 2 shows the arrangement of the ring-shaped magnetic body 27 viewed from above. As shown in FIG. 2, the deflection yoke 26 is a saddle-shaped horizontal disposed vertically symmetrically with the horizontal axis (X-axis) in between, inside the separator 28, and generates a horizontal deflection magnetic field that deflects the three electron beams in the horizontal direction. Deflection coil 29 and a saddle-shaped vertical deflection coil 3 that is arranged symmetrically outside the separator 28 across the vertical axis (Y axis) and generates a vertical deflection magnetic field that deflects the three electron beams in the vertical direction.
0. The pair of horizontal deflection coils 29 have transition parts 31a and 31b on the fluorescent screen side and the opposite electron gun side, respectively, and the pair of vertical deflection coils 30 also have transition parts 31a and 31b on the fluorescent screen side and the opposite electron gun side, respectively. It has spanning parts 32a and 32b, and constitutes a front flange part A and a rear flange part B. Further, a conical cylindrical core 33 is arranged on the outer periphery of the vertical deflection coil 30 so as to avoid the transition portions of the horizontal and vertical coils and surround them. Further, a pair of ring-shaped magnetic bodies 27 with high magnetic permeability and high resistivity are arranged above and below this deflection yoke 26, and the screen side and electron gun side of the ring-shaped magnetic bodies 27 are connected to the deflection yoke 26.
It is located near the front flange part A and the rear flange part B of No. 6. [0016] By installing this ring-shaped magnetic body, ELF (Extremely L
owFrequency) of 5Hz to 2kHz can be reduced. For example, as a magnetic material,
By installing a ring-shaped ferrite core with an outer diameter of 110 mm, an inner diameter of 107 mm, and a height of 8 mm, the leakage magnetic field of the ELF can be reduced from 250 nT to 150 nT or less. Furthermore, by appropriately shaping the magnetic material, the leakage magnetic field can be reduced to 100 nT or less. [0017] Next, the action of this ring-shaped magnetic body will be explained. FIG. 3 shows the leakage magnetic field of the saddle-shaped vertical deflection coil and the compensation effect of the magnetic material. By arranging the ring-shaped magnetic body so as to cover the front and rear flanges of the deflection yoke, the front and rear of the ring-shaped magnetic body are located near the front and rear flanges of the deflection yoke, respectively, and the leakage magnetic field as shown by the solid line is reduced. The magnetic body is magnetized by this, and a compensating magnetic field in the opposite direction to the leakage magnetic field as shown by the broken line is generated. [00181 As mentioned above, in order to generate a compensation magnetic field by magnetizing a magnetic body, it is necessary to place a magnetic body outside the front and rear transition parts of the vertical coil, but since the compensation magnetic field is weak only in that part, the front and rear must be connected. The ring shape increases the volume of the magnetic material and improves its effectiveness. [0019] In addition, if a coma correction coil is installed near the rear flange, this coil also produces a leakage magnetic field, and by installing the ring-shaped magnetic body so as to cover this coil as well, the leakage magnetic field can be reduced. can do.

Furthermore, in the above embodiment, the ring-shaped magnetic bodies are arranged above and below the deflection yoke, but although it is effective to use the ring-shaped magnetic bodies only at the upper part of the deflection yoke, it is preferable to arrange the ring-shaped magnetic bodies in pairs above and below the deflection yoke. It is more effective to use this configuration. [0021] Furthermore, the leakage magnetic field can be minimized by installing the ring in a position that covers the front flange and rear flange of the deflection yoke. [0022] Note that the ring according to the present invention is not limited to a ring shape, and may be a rectangular magnetic body 40 as shown in FIG. [0023] Furthermore, since the ring-shaped or rectangular magnetic body has the effect of reducing only the leakage magnetic field of the ELF due to vertical deflection, if it also serves to reduce the leakage magnetic field due to horizontal deflection, as shown in FIG. Alternatively, a coil 41 may be wound around the front part of the rectangular magnetic body 40 to serve as a part of the compensation coil. With this configuration, the compensation coil 41 is located near the transition portion of the saddle-shaped horizontal deflection coil, which is effective in reducing leakage magnetic flux of the horizontal deflection magnetic field. Further, by adjusting the angle of the rectangular magnetic body, it is possible to adjust the compensation effect of the leakage magnetic flux due to the horizontal deflection magnetic field. [0024] In the above embodiments, ferrite with high magnetic permeability and high resistivity was used as the magnetic material, but in the case of only reducing the leakage magnetic field of ELF, the magnetic material is It is also possible to use materials with low [o 025] Furthermore, in the above embodiment, a saddle-shaped coil was used as the vertical deflection coil.
A toroidal coil may also be used. [0026] By implementing the above-described means for reducing leakage magnetic fields, ITC work becomes easier, the influence on the cathode ray tube device is reduced, and problems such as changes in the design of the cathode ray tube device can be avoided. [0027]

As described above, according to the present invention, the leakage magnetic field generated from a cathode ray tube device can be reduced in a simple manner. Furthermore, it does not interfere with ITC work and eliminates the trouble of changing the design of the cathode ray tube device.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of a cathode ray tube device that is an embodiment of the present invention.

FIG. 2 is a top view showing the arrangement of ring-shaped magnetic bodies disposed above and below the deflection yoke in FIG. 1;

FIG. 3 is a diagram illustrating the action of the ring-shaped magnetic body according to the present invention.

FIG. 4 is a diagram showing a closed rectangular magnetic body that is another embodiment of the present invention.

FIG. 5 is a diagram showing an example in which a compensating coil for horizontal deflection leakage magnetic field is also provided, which is another embodiment of the present invention.

FIG. 6 is a diagram showing an auxiliary coil for reducing leakage magnetic field in a conventional cathode ray tube device.

FIG. 7 is a diagram showing a magnetically permeable ring for reducing leakage magnetic fields in a conventional cathode ray tube device.

[Explanation of symbols]

22. Phosphor screen 25・Electron gun 26. Deflection yoke 27. Ring-shaped magnetic material 29・・Saddle type horizontal deflection coil 30・・Saddle type vertical deflection coil A.・Front flange part B... Rear flange part 40... Rectangular magnetic body

[Figure 3]

Claims (1)

[Claims] 1. A cathode ray tube that displays an image on a phosphor screen by scanning an electron beam emitted from an electron gun;
A horizontal deflection coil that is attached to the cathode ray tube and generates a horizontal deflection magnetic field that horizontally deflects the electron beam emitted from the electron gun, and a vertical deflection magnetic field that vertically deflects the electron beam emitted from the electron gun. The horizontal deflection coil includes a deflection yoke consisting of a pair of upper and lower saddle-shaped horizontal deflection coils, and an outer side of the deflection yoke and at least one side with respect to the plane of symmetry of the saddle-shaped horizontal deflection coil. a closed ring-shaped or rectangular magnetic body disposed in the deflection yoke, and the front side of the magnetic body on the screen side and the rear side on the electron gun side are positioned so as to cover the front flange part and the rear flange part of the deflection yoke, respectively. A cathode ray tube device characterized by: