JP3397836B2 - Deflection yoke - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection yoke provided with a horizontal deflection coil and a toroidal type vertical deflection coil for use in an in-line type cathode ray tube. The present invention relates to a deflection yoke having a front cross arm provided for improvement. 2. Description of the Related Art FIG. 8 is a side view of a conventional deflection yoke provided with a front cross arm, and FIG. 9 is a plan view of the deflection yoke as viewed from an opening side. Here, 1 is a horizontal deflection coil, 2 is a toroidal type vertical deflection coil, and 3 is an annular core. Reference numeral 11 denotes a front cross arm, 11a denotes a magnetic field emission unit of the front cross arm 11, and 11b denotes a magnetic field collection unit of the front cross arm 11. The role of the front cross arm 11 is toroidal type vertical deflection coil 2.
The leaked magnetic field is collected by the magnetic field collection unit 11b and emitted from the magnetic field emission unit 11a provided along the funnel curve, thereby correcting the vertical pincushion raster distortion on the screen of the cathode ray tube. Hereinafter, the movement of the electron beam affected by the emitted magnetic field will be described. FIG. 10 is a raster diagram on a fluorescent screen of a cathode ray tube when a conventional deflection yoke is used.
The distance dt between the diagonal horizontal line and the bright line is smaller than the distance dy between the horizontal line and the bright line on the S-axis (dy> d
Due to t), an aberration occurs in which an image similar to the figure on the object plane cannot be obtained. This is generally referred to as pincushion in the upper and lower raster distortions. FIG. 11 is a view in which the state of deflection of an electron beam in a cathode ray tube on the axis and diagonally is viewed from the N direction. FIG. 12 shows spots of the electron beam deflected in FIG. . 13 to 15 show deflection magnetic fields acting on the electron beam. FIG. 13 shows a pincushion magnetic field, FIG. 14 shows a barrel magnetic field, and FIG. 15 shows a uniform magnetic field. [0005] The following two main causes can be considered as the causes of the vertical raster distortion resulting in the pincushion. One is that the magnification varies depending on the radial distance of the lens. FIG.
As shown in FIG. 1, the distance of the trajectory from when the electron beam is emitted from the electron gun and hits the fluorescent screen of the cathode ray tube is more diagonal than when the electron beam is deflected on the NS axis (da). When deflected to (db), it is longer (da <db). Therefore, the vertical direction (NS direction)
The tendency of the electron beam to deviate is to be greater at the diagonal than at the axis. Second, the vertical magnetic field involved in the vertical deflection is a barrel magnetic field diagram 14. In the case of the barrel magnetic field, the magnetic field involved in the diagonal deflection is smaller than the magnetic flux density 20 of the magnetic field involved in the axial deflection. Has a high magnetic flux density 19,
The deviation in the diagonal direction becomes larger than on the axis. Therefore, it is necessary to improve the deflection sensitivity when deflecting on the axis by some means. As a method therefor, there is a method in which the magnetic field at the opening side of the deflection yoke is converted into a pincushion magnetic field as shown in FIG. 13. One of the means is to use a front cross arm. However, the method of changing the magnetic field to the pincushion magnetic field on the opening side of the deflection yoke results in increasing the deflection sensitivity of vertical deflection by the amount of the magnetic field on the opening side. As a result, the electron beam 22 deflected in the diagonal direction hits the internal glass of the cathode ray tube as shown in FIG. 16 and causes a problem that a shadow 25 appears on the screen of the cathode ray tube called a neck shadow shown in FIG. Become. As shown in FIG. 19, the conventional front cross arm applies an external leakage magnetic field 27 to the front cross arm 1.
The magnetic field is collected by the magnetic field collection unit 11b, and the magnetic field is collected from the magnetic field emission unit 11a shown in FIGS. 8 and 9 to form a pincushion magnetic field at the opening of the deflection yoke. However, since the conventional front cross arm utilizes the external leakage magnetic field 27 radiated in the outer peripheral direction of the vertical deflection coil, the front cross arm has an aperture in addition to the internal deflection magnetic field 26. As a result, the deflection sensitivity of the vertical deflection is increased by an amount corresponding to the increase in the magnetic field on the part side. Then, the above-mentioned neck shadow occurs, and there is a problem that the neck shadow margin 28 as a basic characteristic of the deflection yoke cannot be secured (see FIG. 20). It should be noted that the neck shadow tolerance 28 is shown in FIG.
The deflection yoke 2 with respect to the cathode ray tube as indicated by the dotted line at 0
This is expressed by the amount of movement of the deflection yoke in the tube axis direction until the above-mentioned shadow appears when the electron beam is moved to the electron gun side as shown by a solid line from the state in which 4 is in a dark state. The present invention has been made in view of the above-described problems, and provides a deflection yoke capable of improving the distortion of the upper and lower pincushion rasters and securing a neck shadow tolerance as a basic characteristic of the deflection yoke. The purpose is to: In order to achieve the above object, a horizontal deflection coil and a toroidal type vertical deflection coil wound on an annular core are provided, and four funnel curves are provided in a funnel curve of a cathode ray tube. A magnetic field emitting portion made of a magnetic material is arranged along a funnel curve, and electrons of the annular core are absorbed so as to absorb a deflecting magnetic field and a leakage magnetic field diverging from the electron gun side end face and the vicinity of the end face of the annular core. The deflection yoke has a front cross arm in which a magnetic field collection unit is arranged to face the end face on the gun side. According to the above construction, the magnetic field pickup section absorbs the deflection magnetic field emitted from the electron gun side end face of the annular core and the vicinity of the end face, and the deflection center is set at the center of the annular core. Part (close to the opening of the deflection yoke), it is possible to secure the neck shadow tolerance as a basic characteristic of the deflection yoke, and use the magnetic field on the electron gun side of the annular core having a high magnetic flux density. As a result, it is no longer necessary to enlarge the front cross arm so as to surround the deflection yoke as in the related art, so that the size of the front cross arm can be reduced, and a deflection yoke lighter than the conventional one can be provided. . FIG. 1 is a side view of a deflection yoke according to an embodiment of the present invention, and FIG. 2 is a plan view of the deflection yoke as viewed from an opening side. 1 is a horizontal deflection coil, 2 is a toroidal type vertical deflection coil, 3 is an annular core wound with a toroidal type vertical deflection coil, and 4 is a front cross arm. FIG. 3 is a sectional view for explaining a state of a magnetic field in the front cross arm 4 of the deflection yoke. In the front cross arm 4, reference numeral 4a denotes a magnetic field emission portion composed of four magnetic materials, which are arranged opposite to each other along a funnel curve with the straight portion of the in-line cathode ray tube as an axis. Numeral 4b denotes a magnetic field collection portion of the front cross arm 4, and as shown in FIG. 3, a deflection magnetic field 5a emitted from the electron gun side end surface of the annular core 3 and the vicinity of the end surface.
Is disposed so as to face the electron gun side end surface of the annular core 3 so as to absorb the heat. FIG. 4 is a perspective view of the above-mentioned front cross arm 4. The front cross arm 4 absorbs the deflecting magnetic field and the leakage magnetic field of the toroidal vertical deflection coil 2 by a magnetic field collecting portion, and deflects the absorbed magnetic field. The state of the magnetic field until the magnetic field is emitted by the magnetic field emission part 4a on the opening side is indicated by a white arrow. As is clear from this figure, the magnetic field collection portion 4b of the front cross arm 4 is installed parallel to the radial cross section of the toroidal vertical deflection coil 2. That is, since the deflection magnetic field 5a having a high magnetic flux density is collected in the magnetic field emitted from the toroidal vertical deflection coil 2 shown in FIG. 3, a pincushion magnetic field having a high deflection sensitivity is formed in the magnetic field emission portion 4a. The deflection sensitivity of the deflection yoke on the electron gun side can be reduced by the magnetic field collection unit 4b. As a result, the deflection yoke weakens the barrel component on the electron gun side by the function of the magnetic field collection portion 4b of the front cross arm 4 of the present embodiment, and most effectively affects the vertical pincushion raster distortion correction. A pincushion magnetic field can be formed at the opening of the yoke. FIG. 5 is a graph showing a magnetic field distribution of a vertical magnetic field component of the deflection yoke. A dotted line 7 shows a case where the conventional front cross arm shown in FIGS. 8 and 9 is used, and a solid line 6 shows a case where the front cross arm according to the embodiment of the present invention is used. From this graph, it can be seen that when the conventional front cross arm is used (dotted line), the deflection yoke has the strongest magnetic field near the end face of the annular core 3 on the electron gun side. The fact that the magnetic field at this portion is a barrel magnetic field serves to make the vertical raster distortion a pincushion type, and the leakage magnetic field which does not normally contribute to deflection as shown in FIG. There is no margin for neck shadows. However, in the deflection yoke of this embodiment (solid line 6), the use of the above-mentioned front cross arm 4 allows the pink magnetic field for correcting the vertical raster distortion on the opening side. FIG. 13 shows the deflection sensitivity of the vertical deflection component. Instead of strengthening it, because of its pincushion magnetic field,
Since the magnetic field 5a near the electron gun side end surface of the annular core 3 is used, the deflection sensitivity of this portion is weakened, and the center of deflection can be shifted to the center of the annular core 3 (close to the opening of the deflection yoke). it can. Accordingly, it is possible to prevent the electron beam from hitting the inner glass of the cathode ray tube as shown at 23 in FIG. Therefore, the neck shadow tolerance as a basic characteristic of the deflection yoke can be secured, and for the same reason, it is not necessary to enlarge the front cross arm so as to surround the deflection yoke as in the conventional case. Can be downsized, and a lighter deflection yoke than before can be provided. As described above, according to the present invention, the magnetic field collecting portion of the front cross arm is disposed to face the electron gun side end face of the annular core, and the magnetic field is emitted from the electron gun side end face of the annular core and the vicinity thereof. Since the deflection center can be moved to the opening side by being configured to be able to absorb the generated magnetic field, the configuration is such that the vertical pincushion raster distortion can be corrected while securing the neck shadow tolerance, and the deflection yoke Can be lightened.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a deflection yoke according to an embodiment of the present invention. FIG. 2 is a plan view of the deflection yoke according to the embodiment. FIG. 3 is a front cross arm of the deflection yoke according to the embodiment. FIG. 4 is a perspective view of a front cross arm used in the deflection yoke of the embodiment. FIG. 5 is a graph showing the distribution of a vertical deflection magnetic field of the deflection yoke of the embodiment. FIG. FIG. 7 is an explanatory view of a screen of the cathode ray tube. FIG. 8 is a side view of a conventional deflection yoke. FIG. 9 is a plan view of the conventional deflection yoke viewed from an opening side. FIG. 10 uses a conventional deflection yoke. FIG. 11 is a plan view showing the state of electron beam deflection on the axis and diagonal in the cathode ray tube. FIG. 12 is a plan view showing the state of electron beam deflection in the cathode ray tube. Spot map on the surface [ FIG. 13 is an explanatory view of a deflection magnetic field acting on an electron beam. FIG. 14 is an explanatory view of a deflection magnetic field acting on an electron beam. FIG. 15 is an explanatory view of a deflection magnetic field acting on an electron beam. FIG. 17 is an explanatory view of a screen of a cathode ray tube in which a neck shadow has occurred. FIG. 18 is an explanatory view showing a function of a magnetic field collection unit of a conventional front cross arm. FIG. 19 is an explanatory view of a neck shadow tolerance. Explanation of neck shadow tolerance [Description of symbols] 1 Horizontal deflection coil 2 Toroidal type vertical deflection coil 3 Annular core 4 Front cross arm 4a Magnetic field emission part 4b Magnetic field collection part 5 Vertical deflection magnetic field 5a Electron gun side end face and vicinity of end face Deflection magnetic field emitted from

Claims (1)

(57) [Claims 1] A magnetic field emission comprising a horizontal deflection coil and a toroidal type vertical deflection coil wound on an annular core, and a magnetic field composed of four magnetic materials in a funnel curve of a cathode ray tube. Parts are arranged along the funnel curve, and face the electron gun-side end face of the annular core so as to absorb the deflection magnetic field and the leakage magnetic field diverging from the electron gun-side end face of the annular core and the vicinity of the end face. A deflection yoke having a front cross arm in which a magnetic field collection unit is disposed.