Deflection coil and fabrication method thereof

Abstract: A deflection coil is formed into a saddle shape by winding up a conductive wire ribbon in layers, such that the layered wire ribbon is formed in its cross-section into a parallelogram with adjoining sides crossing one another at other than 90 degrees. The deflection coil is produced by winding up in layers the wire ribbon in a plurality of coil grooves of a coil-winding frame die while the wire ribbon is delivered out from a nozzle, obliquely against the side wall face of each coil groove.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection coil mounted on a deflection yoke for regulating the progressive direction of electron beams emitted from an electron gun for use in television receivers, display units or the like, and a fabrication method thereof. 2. Description of the Prior Art In recent years, development of high-definition and high-brightness television receivers and the appearance of high resolution display units, increasingly tend to demand strict specifications relating to color mismatching (ie. convergence) of the cathode-ray tubes for such apparatus. Thus, it is desirable that a deflection magnetic field be controlled more precisely. Fig. 1 shows an example of a bobbin for a saddle type deflection coil for use in a typical deflection yoke. The bobbin 2 is provided with a plurality of coil-winding grooves 5, on which, for example, a coiling wire 11 is wound in layers as shown in Fig. 2, to thereby form a deflection coil. The coiling wire 11 uses one of conductive wires (including litz wires) with an insulating layer 4 provided thereon which is coated with an adhesive on its external peripheral surface. Fig. 2 is an enlarged view of one of coil-winding grooves 5 shown in Fig. 1. In winding the coiling wire 11 is wound in layers by an automatic winding machine, the wires being wound either singly or in groups of separate wires, whereby a deflection coil is produced. Subsequently, the thus wound layered coil is supplied with electric power, to heat and melt the adhesive applied outside the insulating layer 4, so that the coil wires adhere to each other to complete a deflection coil. Such a prior art deflection coil, however, suffers from disadvantages: owing to variation in the tensioning force acting on the coiling wire 11 as it is wound and other reasons, the coiling wire 11 may be displaced and biassed as shown in Fig. 2, and in other cases, the order of winding of coiling wire 11 is altered and hence the winding configuration specified by the coil designer cannot be achieved. Further, the biased states of coiling wire 11 of mass-produced deflection coils differ from one another and thus it is impossible to regulate a deflection field with high precision. Additionally, mass-production makes variations between products larger, resulting in lowering of the yield, and hence the prior art winding method also has a cost penalty. Whilst in the last-mentioned prior art method, the coiling wire 11 can be reduced in its displacement and biased winding if the width of the coil-winding groove is narrowed, eg. to satisfy an original design requirement, there then arises another problem in that the coil performance deteriorates because of the ratio L/R between inductance L and resistance R being reduced. In order to reduce such problems, the present applicant has previously proposed a deflection coil which is composed by forming a conductive wire row member in which a plurality of adjoining conductive wires are arranged in parallel in a row, and winding this member in place of winding a single wire one by one as used to be practiced. Examples of conductive wire row member (hereinafter called "wire ribbon" ) 15 include one that is composed as shown in Fig. 3A by arranging in parallel a plurality of conductive wires 8 of copper, aluminum or the like with an insulating layer 4 coated thereon, and adhering them using an adhesive 6; one that is composed as shown in Fig. 3B by arranging in parallel a plurality of conductive wires 8 with an insulating layer 4 coated thereon, and adhering together the wires on one side of an insulator sheet 7 of resin, etc., with an adhesive 6; one that is composed as shown in Fig. 3C by arranging and adhering together in parallel a plurality of conductive wires 8 formed with an insulating layer 4 and an adhesive layer 9; and one that is composed as shown in Fig. 3D by arranging a plurality of conductive wires in a contacting manner in a row, each wire being with an insulating layer 4 covered by a thermoplastic adhesive layer 20. The conductive wires 8 forming the aforementioned wire ribbon 15 are arranged in parallel with one another in an orderly manner in a row, and therefore, neither will each conductive wire 8 be displaced in wire ribbon 15, nor will the order of the wires be altered. As a result, by developing a deflection coil having a structure pertinent to using the thus constructed wire ribbon 15, it can be expected to produce a deflection coil free from the problems such as significant displacement of the conductive wires, and the like. The present applicant noticed the fact, and proposed a deflection coil in which wire ribbon 15 is wound in layers such that the cross-section of the layers forms a rectangular shape. The rectangular shape of the cross-section of wire ribbon 15 can be achieved as shown in Fig. 4 by forming bottom faces 10 of coil-winding grooves 5 having flanges 3 to make right angles with corresponding flange faces 13, and winding wire ribbon 15 in layers in parallel with the bottom face 10. The deflection coil formed with the wire ribbon 15 can be remarkably improved in its characteristics as compared with those in the prior art. Meanwhile, when wire ribbon 15 is inserted into coil-winding groove 5, the width of wire ribbon 25 would ideally be the same with that of coil-winding groove 5, but in practice of insertion, the width of wire ribbon 15 exhibits variances, so that wire ribbon 15 may possibly be wider than the groove. In such a case, the wire ribbon 15 should be deformed to be inserted into coil-winding groove 5. Accordingly, a margin or clearance should be provided between wire ribbon 15 and each side wall face of coil-winding groove 5. Nevertheless, if there exists such a clearance as mentioned above when wire ribbon 15 is inserted in coil-winding groove 5, there is a risk that side ends of layered wire ribbons 15 would not be flush with one another, as shown in Fig. 5, because of being wound in a zigzag manner when wire ribbon 15 is wound in layers. Such zigzag layers of wire ribbon 15 might make it difficult to realize a precise control of a deflection magnetic field formed by the deflection coil. Further, as shown in Fig. 4, when the aforementioned wire ribbon 15 is wound in this manner in layers on each of coil-winding grooves 5 formed on bobbin 2, all the cross-sections of layered coils of wire ribbon 15 become rectangular. Accordingly, neighbouring coil-winding grooves 5 create on their sides of bottom faces 10 useless step portions 14 that would have no wound coil, and wire ribbon 15 forms spaces 12 inside coil-winding groove 5 as shown in Fig. 5. In addition, the number of grooves which may be accommodated on the bobbin may be reduced due to their groove widths. These problems lower the space factor of the wires for the deflection coil, and the presence of the step portions may lead to assembly difficulties when the coil is fabricated into a deflection yoke. If the width of coil-winding grooves 5 and the width of wire ribbon 15 are made smaller in order to reduce irregularity or zigzag of layers of wire ribbon 15 as much as possible as shown for example in DE-C-2.744.048, the accuracy of a winding machine for winding ribbon 15 into coil-winding groove 5 must be further improved, and this requires that the input data for the winding machine should additionally include, for example a sequence for identifying the position in which wire ribbon 15 is wound and other factors, thus expanding and complicating the input data. This method also presents difficulty in preparing forming dies for bobbins and metal dies for coiling wires. SUMMARY OF THE INVENTION The present invention is directed to alleviating the above problems, and it is an object of the present invention to provide a deflection coil and a fabrication method thereof wherein electric conductive wires are prevented from being displaced and being disturbed in their order by using a wire ribbon for coil conductive wires forming the deflection coil, and wherein the wire ribbon is prevented from being wound up in zigzag manner, and therefore high dimensional precision and improved space factor of the coil can be achieved. According to one aspect of the present invention there is provided a method of producing a deflection coil by winding in plural layers a wire ribbon in a plurality of coil grooves of a coil-winding bobbin or die comprising the steps of: delivering said wire ribbon obliquely into the groove against a side wall of a said coil groove; and winding up said wire ribbon into said coil groove in layers, wherein the width of the coil groove may be smaller than that of said wire ribbon said wire ribbon being delivered into the groove so that its edges abut opposite side walls of the groove. In another aspect of the present invention, there is provided a deflection coil comprising a conductive wire ribbon disposed in a plurality of layers in a plurality of grooves of a coil-winding bobbin or die, characterised in that said layers of wire ribbon are formed in cross-section into a parallelogram with adjoining sides intersecting at other than 90 degrees, the ribbons being wider than the grooves and the layers being arranged obliquely relative to the sides of the groove. The layers of ribbon may be disposed in a groove in a bobbin, the ribbon being wider than the groove and the layers being arranged obliquely relative to the sides of the groove. The deflection coil may be formed in a saddle shape. As described above, in accordance with a preferred form of the invention, in forming a saddle-shaped deflection coil by winding the wire ribbon in layers into the coil grooves in a coil-winding frame die of a saddle shape while the wire ribbon is delivered out from a nozzle, the wire ribbon is wound around into the coil grooves while delivered obliquely against the wall side of coil groove so that the both sides of the wire ribbon abut against the respective side walls of the groove. By this method, it is possible to prevent the wires from being displaced in the wire ribbon, as well as to prevent the order of the wires being altered. In addition, it is possible to wind up the wire ribbon into coil grooves having a width of not more than that of the wire ribbon, so that the wire ribbon is wound up without being zigzagged, and positioned by the groove side walls. As a result, it is possible to produce a saddle type deflection coil having excellent dimensional accuracy and space factor of the coil wires. Accordingly. an accurate control of a deflection magnetic field can be realized. The above and many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the following detailed description and accompanying drawings in which preferred structural embodiments incorporating the principles of the present invention are shown by way of illustrative example. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic perspective view showing an example of a bobbin used in a conventional deflection-coil; Fig. 2 is an illustration showing a state of coil-windings in a conventional deflection coil; Figs. 3A to 3D are schematic perspective or sectional views showing a different types of conventional wire ribbons; Fig. 4 is a partial illustration of a deflection coil formed by winding a conventional wire ribbon in layers; Fig. 5 is an enlarged cross-sectional view showing a coil-winding groove portion shown in Fig.4; Fig. 6 is a cross-sectional view of a deflection coil showing an ideal layered state of conventional wire ribbon; Fig. 7 is a schematic illustrative view showing a state of wire ribbon being wound in layers in a saddle type deflection coil in accordance with an embodiment of the present invention; Fig. 8 is an enlarged view showing a coil-winding portion of the deflection coil shown in Fig.7; Fig. 9 is an illustration of a saddle type deflection coil in accordance with an embodiment of the present invention; Fig. 10 is an illustration showing a saddle type deflection coil of the invention after the separation from a wire-winding metal die; Figs. 11A and 11B are illustrative views showing a state in which a wire ribbon is inserted in a wire-winding groove in the same saddle type deflection coil; Figs. 12A and 12B are illustrative views showing bottom shapes of coil-winding groove in a saddle type deflection coil in accordance with an embodiment of the present invention; Figs. 13A to 13C are illustrative views showing different slope shapes of coil-winding groove in a saddle type deflection coil; and Fig. 14 is an illustrative view showing a state in which a wire ribbon is wound in layers into a coil-winding groove in a wire-winding metal die for the same saddle type deflection coil. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention will be further described in detail with reference to some preferred embodiments shown in the accompanying drawings (Figs. 7 to 14). In the drawings, like reference numerals will be allotted for the same parts with those in the aforementioned conventional example, and the detailed description for these parts will not be repeated. Fig. 7 is a schematic illustrative view showing a state of wire ribbon being wound in layers in a saddle type deflection coil in accordance with an embodiment of the present invention. The characteristic feature of this embodiment lies in that a wire ribbon 15 is inserted obliquely against a flange face (a side wall face) 13 of a coil-winding groove 5 disposed in a bobbin 2 while wound in layers so that the layered wire ribbon 15 is formed in its cross-section into a parallelogram other than a rectangle, ie. with adjoining sides intersecting at other than 90 degrees (this parallelogram will be hereinafter abbreviated merely as "parallelogram"), and the other configurations are the same as those in the prior art. In Fig. 7, saddle-shaped bobbin 2 is provided with a plurality of coil-winding grooves 5 (A 1 to A 10 ) having flanges 3. The bottom faces 10 of coil-winding grooves 5 designated by A 1 , and A 10 in the bottom base portion 19 of bobbin 2 are formed such as to make an angle approximately close to a right angle against flange faces (side wall face of grooves) 13, and the angle gradually becomes smaller than 90 degrees toward the portions of coil-winding grooves 5 designated by A 5 and A 6 . The angles for the grooves A 5 and A 6 are set about 40 degrees. On the other hand, the widths of coil-winding grooves 5 become narrower successively from grooves A 1 and A 10 toward grooves A 5 and A 6 . The width W of the coil-winding groove 5 is related to the wire ribbon 15 as shown in Fig. 8. That is, a relation W=W 0 sin  holds where W, W 0 and  designate the width of coil-winding groove 5, the width of wire ribbon 15 and an inclination angle formed between flange face 13 and bottom face 10, respectively. Therefore, it is possible to make the width of the coil-winding groove less than that of wire ribbon 15. In winding wire ribbon 15 into these coil-winding grooves 5, wire ribbon 15 is made inclined obliquely against flange face 13 so that the wire ribbon can be wound smoothly into any of coil-winding grooves 5. In the present embodiment, the inserting angle of wire ribbon 15 into the groove is 45 degrees against flange face 13. Flange 3 of the aforementioned coil-winding groove 5 is formed with a rounded face 18 in the inside of its tip, as shown in Fig. 8. With this smoothing treatment of rounded face 18, wire ribbon 15 can be inserted smoothly in a more assured manner into coil-winding groove 5. The wire ribbon 15 is successively wound in layers around coil-winding groove 5, to form a cross-section of layered wire ribbon 15 into a parallelogram. Next, relevant steps in the manufacture of a saddle type deflection coil will be described. Figs. 11A and 11B show a nozzle slot 16 for manufacturing a saddle type deflection coil. Provided on a base side A of the nozzle slot 16 is a nozzle rotary shaft (not shown), which rotates to allow a tip portion 17 of nozzle slot 16 to rotate freely in any direction. The aforementioned wire ribbon 15 is delivered out through nozzle slot 16, and tip portion 17 of the nozzle slot 16 is fixed inclined 45 degrees against flange face (side wall face of groove) 13 of coil-winding groove 5. When a wire ribbon 15 having a width of more than that of coil-winding groove 5 is inserted into the coil-winding groove 5 from the nozzle tip portion 17, the wire ribbon 15 is delivered smoothly into coil-winding groove 5 with the help of rounded face 18 of flange 3 while remaining inclined 45 degrees against flange face 13, whereby the wire ribbon 15 is wound up in layers successively without forming any space on either side of wire ribbon 15 in coil-winding groove 5. Thus, wire ribbon 15 is wound in layers having the cross-section of a parallelogram. In this manner, wire ribbon 15 is wound up in layers, successively for example, in the grooves 5 of A 1 to A 5 of bobbin 2 shown in Fig. 7. Subsequently, when the winding enters the groove 5 designated by A 6 , the tip portion 17 of nozzle slot 16 is rotated 180 degrees about the nozzle rotary shaft on the base side A of nozzle slot 16 as a supporting point thereof. With this rotation, the inclined direction of wire wire ribbon 15 becomes opposite to that for the grooves A 1 to A 5 , but the inserted angle of wire ribbon 15 against flange face 13 is unchanged at 45 degrees. In this state, wire ribbon 15 is wound up into layers successively from the groove 5 of A 6 to the groove 5 of A 10 , to form a saddle-shaped deflection coil shown in Fig. 9. After this, the wire ribbon 15 is developed into one-body structure by heating by supplying electric power to fuse and solidify the coil. Alternatively, the wire ribbon 15 is consolidated by injecting a filler type resin into the layered coil. Thus a saddle type deflection coil can be formed. In this connection, a side view of nozzle slot 16 and a front view of the same are shown in Figs. 11A and 11B, respectively. According to this embodiment, since wire ribbon 15 is wound up in layers to form a saddle type deflection coil, neither will single conductive wires be displaced in wire ribbon 15, nor will the order of the wires be altered. Further, the saddle type deflection coil is prepared by winding up in layers wire ribbon 15 which is kept inclined against flange face 13 while being delivered from nozzle slot 16, and is successively inserted into coil groove 5 that has a width equal to or less than that of wire ribbon 15, so that both sides of wire ribbon 15 are abutted against flange faces 13 of coil-winding groove 5, to thereby be restricted in position. By this restriction, it is possible to wind up wire ribbon 15 in accordance with an original design instruction, preventing wire ribbon 15 from being wound up zigzagged, so as not to leave any space or clearance between both sides of wire ribbon 15 and flange faces 13 of a coil-winding groove 5. In addition, it is possible to increase the number of coil-winding grooves by making the width of a groove narrow, to improve significantly the space factor of the deflection coil. Accordingly, an accurate control of a deflection magnetic field can be realized. Thus a wire ribbon 15 having a width of more than that of coil-winding groove 5 is wound up in layers while being inserted obliquely against flange face 13 of coil-winding groove 5 disposed in bobbin 2, and the layered wire ribbon 15 is formed in its cross-section into a parallelogram, so that both sides of wire ribbon 15 are abutted against flange faces 13 of coil-winding groove 5. As a result, it is not necessary to impose a strict dimensional tolerance on the width of coil-winding groove 5 when it is produced, and therefore, the manufacture of bobbin forming dies and/or wire-winding metal dies can be simplified. Further, since there will be no need for a sequence such as to confirm one by one the winding position of wire ribbon 15, the required precision of the winding machine to be used can be relaxed, and therefore the time for inputting the winding configuration specification into the winding machine can be reduced. In addition, it is possible to form a smooth peripheral surface of the coil by eliminating steps that would be formed on the peripheral surface of the coil. Accordingly, an assembling condition in assembling the deflection coil may be improved. It should be noted that the present invention is not limited to the above embodiment, but various practical configurations can be adopted. For example, though the shape of bottom face 10 of coil-winding groove 5 is not limited particularly in the above embodiment, bottom face 10 may be formed into any shape such as, for example, flat as shown in Fig. 12A, or can be arc-shaped as shown in Fig. 12B. A slant face 23 can be formed in advance with a base member 21 of an insulating material or the like, as shown in Figs. 13A and 13B, for filling the portion of a space 22 formed between bottom face 10 of coil-winding groove 5 and wire ribbon 15 shown in Figs. 12A and 12B. It is also possible to form the bottom face 10 itself into a slant face 23 as shown in Fig. 13C. An extremely slight margin 12 relatively smaller than that in the referenced example is preferably provided between flange face 13 and the side end of wire ribbon 15, although is not essential. In this case, when wire ribon 15 is wound up in layers in coil-winding groove 5, wire ribbon 15 may abut against, and be positioned by, one of flange faces 13 and bottom face 10 despite of the margin 12 being provided, and since the margin is extremely small, wire ribbon 15 can be smoothly wound up in layers with the help of the slight clearance, without being wound up in a zigzag manner. In the above embodiment, wire ribbon 15 is wound up in layers on coil-winding groove 5 of bobbin 2 to be formed into a deflection coil having a layered cross-section of a parallelogram, but as shown in Fig. 14, for example, wire ribbon 15 can be developed into one-body structure by heating by supplying electric power to fuse and solidify the coil or by hardening it with a filler type resin, after having wound up in layers on coil-winding groove 5 of a wire-winding metal die 21 to form a layered structure of parallelogram cross-section. The thus integrated layered coil may be separated from wire-winding metal die 21 to form a saddle type deflection coil as shown in Fig. 10.

Claims: A method of producing a deflection coil by winding in plural layers a wire ribbon (15) in a plurality of coil grooves (5) of a coil-winding bobbin or die comprising the steps of: delivering said wire ribbon obliquely into the groove against a side wall (13) of a said coil groove; and winding up said wire ribbon into said coil groove in layers, wherein the width of said coil groove (5) is smaller than that of said wire ribbon (15) said wire ribbon being delivered into the groove so that its edges abut opposite side walls (5) of the groove. A method of producing a deflection coil according to Claim 1, wherein the end portion (18) of said side wall of said coil groove is rounded so that said wire ribbon may be smoothly inserted into said coil groove. A deflection coil comprising a conductive wire ribbon disposed in a plurality of layers in a plurality of grooves of a coil-winding bobbin or die, characterised in that said layers of wire ribbon (15) are formed in cross-section into a parallelogram with adjoining sides intersecting at other than 90 degrees, the ribbons being wider than the grooves and the layers being arranged obliquely relative to the sides of the groove. A deflection coil according to Claim 3 wherein the coil is saddle-shaped.

Inventors: IKEUCHI HIROSHI, IKEUCHI, HIROSHI
Applicants: MURATA MANUFACTURING CO, MURATA MANUFACTURING CO., LTD.
Application year: 1993
Main classification: H01J9
IPC codes: H01F5, H01J9, H01F41