Abstract:
A deflection yoke is comprised of a separator for insulating horizontal and vertical deflection coils, the horizontal deflection coils of saddle type are provided within and top and bottom portion of the separator respectively, the separator has ribs for partly separating the top and bottom of horizontal deflection coils at their confronted portions, so that the confronted portions confront directly each other where the ribs are not present, thereby a magnetic field generated by the horizontal deflection coils is collected depending on a location and configuration of the ribs.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the invention 
     The present invention relates to a deflection yoke for a in-line 3-guns color picture tube, particularly relates to a deflection yoke for reducing misconvergence of the color picture tube. 
     2. Description of the prior art 
     Referring to FIGS. 1 through 7, a description is given of a self convergence type deflection yoke of a prior art for landing each of 3 beams respectively generated by in-line 3-guns on a screen of a color picture tube. 
     FIG. 1 shows a construction of a deflection yoke 1 for the in-line 3-guns color picture tube. The deflection yoke 1 has a funnel shape, and is comprised of a pair of separators 2, 2 each forming a large circular brim 1a and a small circular brim 1b. At an inside of the separators 2, 2, there is a pair of horizontal deflection coils 3, 3 (not shown in FIG. 1) in a form of saddle. Outside of the separators 2, 2, there is a pair of vertical deflection coils 4, 4 in a form of saddle. The separator 2 is made of resin, and isolates the pair of horizontal deflection coils 3, 3 from the pair of vertical deflection coils 4, 4. The pair of horizontal deflection coils 3, 3 are positioned above and below of the in-line 3-guns of the color picture tube. The pair of vertical deflection coils 4, 4 are positioned left and right thereof. Cores 5, 5 are disposed on each outside of the vertical deflection coils 4, 4. There are first and second flanges 6a and 6b near of the small circular brim 1b. Many parts are assembled to the first and the second flanges 6a and 6b. A circuit board 7 is clipped on the first flange 6a, hanging from the small circular brim 1b to the large circular brim 1a. 
     Such a deflection yoke as mentioned above is so called a saddle-saddle type. 
     As shown in FIG. 2(A), the pair of horizontal deflection coils 3, 3 has a saddle shape and positioned along an inner surface of the separator 2. The horizontal deflection coil 3 has a small rim 3b, a large rim 3a, and a window 3d. A bottom end of an intermediate portion 3c of the horizontal deflection coil 3 is formed by pressing in its production process to form a flat surface which is called a pressed plane 3c1 , and confronted with another pressed plane 3c1. As shown in FIG. 2(B), the pair of vertical deflection coil 4, 4 is similar to the pair of horizontal deflection coil 3, 3 in the shape, and positioned along an outer surface of the separator 2. The vertical deflection coil 4 has same portions of that of the horizontal deflection coil 3, such as a small rim 4b, a large rim 4a, a window 4d, and an intermediate portion 4c. 
     Functions of the horizontal deflection coil 3 and that of the vertical coil 4 are explained referring to FIGS. 3(A) and 3(B). FIGS. 3(A) and 3(B) show sectional views of the deflection yoke 1 and a neck part of a color picture tube 8 cut along the X-Y plane. FIG. 3(A) shows a magnetic field induced by the pair of horizontal deflection coil 3, 3. FIG. 3(B) shows a magnetic field induced by the pair of vertical deflection coil 4, 4. 
     In FIG. 3(A), two intermediate portions 3c, 3c shown above the X axis is one of the horizontal deflection coil 3, and two intermediate portions 3c, 3c shown below the X axis is the other horizontal deflection coil 3. The magnetic field induced by the pair of horizontal deflection coils 3, 3 has a pincushion distortion as shown in FIG. 3(A). 
     On the other hand, at each intermediate portions 4c, 4c of right and left sides of the Y axis, there are the vertical deflection coils 4, 4 respectively. The magnetic field induced by the pair of vertical deflection coil 4, 4 has a barrel distortion as shown in FIG. 3(B). 
     The deflection yoke 1 having such horizontal deflection coil 3 and vertical deflection coil 4 as the above adjusts a convergence of the color picture tube 8 by changing the magnetic field of the horizontal deflection coil 3 and/or the vertical deflection coil 4, by adding a circuit for adjustment to a horizontal deflection circuit and/or a vertical deflection circuit, and attaching a magnetic material to the color picture tube 8. 
     By these functions of the above, three electron beams of R, G, B emitted respectively from three electron guns land on a screen of the color picture tube 8. 
     FIG. 4 shows a frontal view of the deflection yoke 1 seen from the side of the large circular brim 1a. Here, only the separator 2 and the pair of horizontal deflection coils 3, 3 are shown for simplicity. Ribs 2a, 2a are provided inside of the separator 2 on the X axis thereof, for positioning the pair of horizontal deflection coil 3, 3 and isolating the pressed planes 3c1, 3c1 each other at a distance of more than 1 mm. The rib 2a is unitarily molded with the separator 2, extending from the large circular brim 1a to the small circular brim 1b. 
     FIG. 5 shows a sectional view of the deflection yoke 1 mounted on the color picture tube 8. The horizontal deflection coil 3, the vertical deflection coil 4 and the core 5 are shown here, and others are omitted for simplicity. 
     FIG. 6 shows a sectional view of the pair of horizontal deflection coils 3, 3 and a color picture tube 8 of the prior art taken along line A-A&#39; of FIG. 5. The pair of horizontal deflection coils 3, 3 is separated each other in a predetermined distance by the ribs 2a, 2a. 
     Actual magnetic field induced by the pair of horizontal deflection coils 3, 3 is shown in FIG. 6. Horizontal deflection coils 3, 3 of the pair, are spaced each other by a distance &#34;L&#34; which is more than 1 mm as shown in FIG. 6. Under this condition and when convergence of horizontal R/B lines, R and B/G lines are attempted to be optimized, the pincushion distortion of the magnetic field in an area &#34;a&#34;, corresponding to an area &#34;a&#34; of FIG. 5, is weakened. The same in an area &#34;b&#34;, corresponding to an area &#34;b&#34; of FIG. 5, is, on the other hand, strengthened. 
     Owing to the distortion of the magnetic field of the above, at the right and left end zones of the screen, landing positions of red beam and blue beam do not agree with each other in the horizontal direction, as shown in FIG. 7, this is called a &#34;B&#34; type misconvergence. 
     The &#34;B&#34; type misconvergence is a serious problem for a deflection yoke of high definition display tube. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a deflection yoke capable of reducing the &#34;B&#34; type misconvergence. 
     Another object of the present invention is to provide a deflection yoke which presents design flexibility of coil formation of a horizontal deflection coil. 
     Further and another object of the present invention is to provide a separator of a defection yoke capable of reducing the &#34;B&#34; type misconvergence. 
     A specific object of the present invention is to reduce the aforementioned problem by providing a deflection yoke having a pair of horizontal deflection coils of saddle type provided along one side of a separator, and a pair of vertical deflection coils provided along another side of the separator, wherein pressed planes of the pair of horizontal deflection coils are confronted closely with each other a part thereof. 
     Another specific object of the present invention is to reduce the aforementioned problem by providing a deflection yoke having a pair of horizontal deflection coils of saddle type provided along one side of a separator, and a pair of vertical deflection coils provided along another side of the separator, wherein the separator has ribs to keep a limited distance between the pressed planes of respective horizontal deflection coils of the pair. 
     Further and another specific object of the present invention is to reduce the aforementioned problem by providing a deflection yoke having a pair of horizontal deflection coils of saddle type provided along one side of a separator, and a pair of vertical deflection coils provided along another side of the separator, wherein the separator has ribs for keeping a limited distance between the pressed planes of respective horizontal deflection coils of the pair across the ribs. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a perspective view of a deflection yoke of the prior art; 
     FIG. 2(A) shows a pair of horizontal deflection coils of the prior art; 
     FIG. 2(B) shows a pair of vertical deflection coils of the prior art; 
     FIG. 3(A) shows a magnetic field induced by a pair of horizontal deflection coils of the prior art; 
     FIG. 3(B) shows a magnetic field induced by a pair of vertical deflection coils of the prior art; 
     FIG. 4 shows a frontal view of a deflection yoke of the prior art seen from the side of a large brim; 
     FIG. 5 shows a sectional view of a deflection yoke and a color picture tube of the prior art; 
     FIG. 6 shows a sectional view of a pair of horizontal deflection coils and a color picture tube of the prior art taken along line A-A&#39; of FIG. 5; 
     FIG. 7 shows a screen of a color picture tube for explaining a misconvergence of the prior art; 
     FIG. 8 shows a frontal view of a deflection yoke of first embodiment of the present invention seen from the side of a large brim; 
     FIGS. 9(A) and 9(B) show frontal and sectional views of a deflection yoke of second embodiment of the present invention; 
     FIG. 10 shows a perspective view of a horizontal deflection coil of second embodiment of the present invention; 
     FIG. 11 shows a sectional view of a pair of horizontal deflection coils and a color picture tube of the present invention taken along line A-A&#39; of FIG. 5 and modified to show the features of the present invention; 
     FIGS. 12(A) and 12(B) show frontal and sectional views of a deflection yoke of third embodiment of the present invention; 
     FIGS. 13(A) and 13(B) show frontal and sectional views of a deflection yoke of fourth embodiment of the present invention; 
     FIGS. 14(A) and 14(B) show frontal and sectional views of a deflection yoke of fifth embodiment of the present invention; 
     FIG. 15(A) shows a perspective view of a pair of horizontal deflection coils for explaining a way of winding; and 
     FIG. 15(B) shows a perspective view of a pair of horizontal deflection coils for explaining another method of winding. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A deflection yoke according to the present invention will be described in detail with reference to the accompanying drawings, in which same reference numerals and symbols are used to denote like or equivalent elements used in the aforementioned prior arts, and detailed explanations of such elements are omitted for simplicity. 
     FIG. 8 shows a frontal view of a deflection yoke of first embodiment of the present invention seen from the side of a large brim. 
     FIGS. 9(A) and 9(B) show frontal and sectional views of a deflection yoke of second embodiment of the present invention. 
     FIG. 10 shows a perspective view of a horizontal deflection coil of second embodiment of the present invention. 
     FIG. 11 shows a sectional view of a pair of horizontal deflection coils and a color picture tube of the present invention taken along line A-A&#39; of FIG. 5 and modified to show the features of the present invention. 
     FIGS. 12(A) and 12(B) show frontal and sectional views of a deflection yoke of third embodiment of the present invention. 
     FIGS. 13(A) and 13(B) show frontal and sectional views of a deflection yoke of fourth embodiment of the present invention. 
     FIGS. 14(A) and 14(B) show frontal and sectional views of a deflection yoke of fifth embodiment of the present invention. 
     FIG. 15(A) shows a perspective view of a pair of horizontal deflection coils for explaining a way of winding. 
     FIG. 15(B) shows a perspective view of a pair of horizontal deflection coils for explaining another way of winding. 
     A deflection yoke of the present invention is almost same as a deflection yoke of the prior art shown in FIG. 1 in most of its constructions except for its horizontal deflection coils and separator. Accordingly, explanations will be given to the horizontal deflection coils and the separator, and omitted for others. 
      First Embodiment! 
     An explanation will be given to a first embodiment of the present invention. 
     FIG. 8 shows a frontal view of a deflection yoke 10 of first embodiment of the present invention seen from the side of a large brim. 
     A pair of separators 12, 12 (left and right) and a pair of horizontal deflection coils 13, 13 (upper and lower) are shown in FIG. 8. 
     Horizontal deflection coils 13, 13 are provided inside of and upper and lower sides of the pair of separators 12, 12 respectively. The pair of horizontal deflection coils 13, 13 has a large rim 13a, 13a, a small rim 13b, 13b, an intermediate portion 13c, 13c, pressed planes 13c1, 13c1 on respective sides thereof, and a window 13d, 13d interposed between the intermediate portions 13c, 13c. 
     The pair of separators 12, 12 of a deflection yoke 10 of the first embodiment has no ribs for separating the pressed planes 13c1, 13c1 each other at some distance away as shown in FIG. 8, and the pressed planes 13c1, 13c1 are electrically insulated but physically and directly confronting each other across an air gap. The distance between the pressed planes 13c1, 13c1 is preferable to be less than 1 mm, more preferable to be 0.7 mm, and the best to contact firmly. 
      Second Embodiment! 
     FIGS. 9(A) and 9(B) show respectively frontal and sectional views of a deflection yoke 10 of second embodiment of the present invention seen from a front and a top of the deflection yoke 10. 
     In the second embodiment, as shown in FIGS. 9(A) and 9(B), ribs 12a, 12a are provided partly between the pressed planes 13c1, 13c1, so that the upper and lower horizontal deflection coils 13, 13 are kept apart each other where the ribs 12a, 12a are present. The ribs 12a, 12a extend along the pressed planes 13c1, 13c1 from the small rim 13b (rear of the deflection yoke 10) toward the large rim 13a (front) but are terminated at a halfway between them, so that the pressed planes 13c1, 13c1 confront directly each other in vicinity of the large rim 13a as shown by hatching in FIG. 9(B). 
     FIG. 10 shows a perspective view of a horizontal deflection coil of second embodiment of the present invention. 
     A horizontal deflection coil 13 of the second embodiment has a projection 13c2 which is a part of winding of the pressed plane 13c1, the projection 13c2 is disposed close to the large rim 13a when assembled thereto. When the pair of horizontal deflection coils 13, 13 of the second embodiment is provided on the pair of separators 12, 12 of FIG. 9(A), these projections 13c2 are directly confronting each other. The projection 13c2 and other edges of the horizontal coil 13 are formed by a pressing process called a &#34;stepped press&#34; work. 
     An electron beam of a color picture tube 8 is deflected more at the position of the large rim 13a than at the small rim 13b thereof. As the pressed plane 13c1 of the second embodiment is directly contacting with the another pressed plane 13c1, a magnitude of deflection caused at the contacting area is enhanced relatively. 
     FIG. 11 shows a sectional view of a pair of horizontal deflection coils and a color picture tube of the present invention taken along line A-A&#39; of FIG. 5 and modified to show the features of the present invention. 
     In FIG. 11, a magnetic field induced by the pair of horizontal deflection coils 13, 13 is shown. At the area near the large rim 13a , the pressed planes 13c1, 13c1 confront each other. This is a modification of the cross-section of FIG. 5 to illustrate the features of the present invention. Therefore, a pincushion magnetic field is stronger in the area &#34;a&#34; than that of the prior art (FIG. 6), and is less in the area &#34;b&#34;. Accordingly, the horizontal deflection coil 13 of the second embodiment improves a &#34;B&#34; type misconvergence shown in FIG. 7. 
      Third Embodiment! 
     FIGS. 12(A) and 12(B) show frontal and sectional views of a deflection yoke 10 of third embodiment of the present invention seen from a front and a top of the deflection yoke 10. 
     In the third embodiment, the ribs 12a, 12a are provided only in a mid area between the large and small rims 13a and 13b as shown in FIG. 12(B), so that the pressed planes 13c1, 13c1 confront directly each other in vicinities of the large and small rims 13a and 13b as hatched areas in FIG. 12(B). 
      Fourth Embodiment! 
     FIGS. 13(A) and 13(B) show respectively frontal and sectional views of a deflection yoke of fourth embodiment of the present invention seen from a front and a top of the deflection yoke 10. 
     In the fourth embodiment, 2 sets of ribs are provided. As shown in FIG. 13(B), ribs 12a1, 12a1 extend from the vicinity of the small rim 13b and are terminated short of a mid point between the large and small rims 13a and 13b, another set of ribs 12a2, 12a2 extend from the vicinity of the large rim 13a and are terminated short of the mid point leaving the mid area for a direct facing of the pressed planes 13c1, 13c1 as shown by hatching in FIG. 13(B). 
      Fifth Embodiment! 
     FIGS. 14(A) and 14(B) show respectively frontal and sectional views of a deflection yoke of fifth embodiment of the present invention seen from a front and a top of the deflection yoke 10. 
     In the fifth embodiment, the ribs 12a, 12a are provided extending from a vicinity of the large rim 13a beyond the mid point but short of the small rim 13b, so that the pressed planes 13c1, 13c1 confront directly each other in vicinity of the small rim 13b as hatched area shown in FIG. 14(b). 
     In the second through fifth embodiments, a parted distance between the pressed planes 13c1, 13c1 is equal to a thickness of the ribs 12a, 12a, therefore, by varying the thickness, the parted distance between the pressed planes 13c1, 13c1 can be controlled in a range from the thickness of the ribs 12a, 12a to zero distance where no ribs are present, that is, they contact each other directly without a rib. As an example, thickness of the ribs 12a1 and 12a2 in the fourth embodiment are 3 mm at a front end of the rib 12a2 and slightly less than 2 mm at a rear end of the rib 12a1. 
     In addition to the thickness of the ribs 12a, 12a, an area to allow the direct contact of the pressed planes 13c1, 13c1 can be controlled by changing a width, length and location of the ribs 12a, 12a in positional relationship of the pressed planes 13c1, 13c1, consequently, the magnetic field induced by the horizontal deflection coils 13, 13 can be controlled according to a configuration of these ribs 12a, 12a as a design option. The rib 12a may be molded as an integral part of the separator 12 or a separate piece. 
     The pair of horizontal deflection coils 13, 13 of the first through fifth embodiments improves a misconvergence shown in FIG. 7, as pressed planes 13c1, 13c1 contact with at least partly each other. The pressed planes 13c1, 13c1 of the present invention are disposed closer each other than those of the prior art shown in FIG. 4. This means an increase of space available for accommodating wires of the horizontal deflection coils 13, 13, in turn, this presents more design flexibility of coil formation, that is a physical arrangement of coil wires in the area &#34;a&#34;. Otherwise, the area &#34;a&#34; is considerably taken up by the ribs 2a, 2a of more than 1 mm thick, in the case of the prior art. As a result, the deflection yoke 10 of the present invention can reduce not only the &#34;B&#34; type misconvergence, but also another type of misconvergence and a raster distortion. 
     Since the deflection yoke 10 of second through fifth embodiments has ribs 12a, 12a on the separator 12, which serves as a positioner, it is easy to mount the horizontal deflection coils 13, 13 on the separator 12. 
     When the pressed planes 13c1, 13c1 physically contact each other, it is important to secure electronic insulation between the horizontal deflection coils 13, 13 by increasing a dielectric strength thereof or winding them reversely each other called &#34;reverse winding&#34; to reduce an electric potential difference therebetween. 
     Next, normal and reverse windings will be explained referring to FIGS. 15(A) and 15(B). FIG. 15(A) shows horizontal deflection coils 13, 13 wound in a same direction respectively. FIG. 15(B) shows horizontal deflection coils 13, 13 wound reversely each other. 
     In FIG. 15(A), a start terminal of the upper horizontal deflection coil 13 is connected to a finish terminal of the lower horizontal deflection coil 13, and a finish terminal of the upper horizontal deflection coil 13 is connected to a start terminal of the lower horizontal deflection coil 13. When an electric current flows to the pair of deflection coils 13, 13, an electric potential is produced between the pressed planes 13c1, 13c1. 
     In FIG. 15(B), the start terminal of the upper horizontal deflection coil 13 is connected to the start terminal of the lower horizontal deflection coil 13, and the finish terminal of the upper horizontal deflection coil 13 is connected to the finish terminal of the lower horizontal deflection coil 13. By this connecting arrangement, no electric potential difference is produced between the pressed planes 13c1, 13c1. Thus, there occurs no insulation break down on the pressed planes 13c1, 13c1. 
     The advantage of the present invention is to be capable of reducing the &#34;B&#34; type misconvergence by providing the pressed planes physically and directly contacting each other. 
     The another advantage of the present invention is to be capable of reducing other kind of misconvergence and the raster distortion by improving the space factor of the pressed plane and the productivity of the deflection yoke.