US3889218A

US3889218A - Saddle shaped deflection coil

Info

Publication number: US3889218A
Application number: US495293A
Authority: US
Inventors: Yoji Ishikawa
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 1973-08-21
Filing date: 1974-08-06
Publication date: 1975-06-10
Anticipated expiration: 1992-06-10

Abstract

A saddle type deflection coil for a cathode ray tube has cross sections, taken in planes perpendicular to a first axis corresponding to the longitudinal central axis of the cathode ray tube, which each consists of a pair of half sectional portions symmetrical about a second axis perpendicular to the first axis, each of the half sectional portions having an outer curved margin formed by an arc of a circle centered at the first axis and an inner margin having a curved part formed by an arc of another circle also centered at the first axis and a straight part extending from the curved parallel with the second axis. An apparatus for winding a saddle type deflection coil includes male and female members which, when mated, form a cavity into which the deflection coil mentioned as above is wound, whereby it becomes much easier to manufacture the coil winding apparatus and the deflection coils wound by the apparatus are of uniform quality and have good characteristics.

Description

United States Patent lshikawa June 10, 1975 1 1 SADDLE SHAPED DEFLECTION COIL [751 Inventor: Yoji lshikawa, Saitama, Japan [73] Assignee: Sony Corporation, Tokyo, Japan [22] Filed: Aug. 6, 1974 [21] Appl. No.: 495.293

Primary ExaminerG. Harris Attorney, Agent, or Firm-Lewis H. Eslinger; Alvin Sinderbrand [57] ABSTRACT A saddle type deflection coil for a cathode ray tube has cross sections, taken in planes perpendicular to a first axis corresponding to the longitudinal central axis of the cathode ray tube, which each consists of a pair of half sectional portions symmetrical about a second axis perpendicular to the first axis, each of the half sectional portions having an outer curved margin formed by an arc of a circle centered at the first axis and an inner margin having a curved part formed by an arc of another circle also centered at the first axis and a straight part extending from the curved parallel with the second axis. An apparatus for winding a saddle type deflection coil includes male and female members which, when mated, form a cavity into which the deflection coil mentioned as above is wound, whereby it becomes much easier to manufacture the coil winding apparatus and the deflection coils wound by the apparatus are of uniform quality and have good characteristics.

4 Claims, 17 Drawing Figures SHEET PATENTEDJUH 10 I975 PATENTEU JUN I 0 I975 SHEET I I I I Z6 I I (M120 Baz 40 60 50 1 SADDLE SHAPED DEFLECTION COIL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a saddle type deflection coil for a cathode ray tube and its winding apparatus.

2. Description of the Prior Art A saddle type deflection coil is widely used for a cathode ray tube of a conventional television receiver and many improvements have been proposed in the prior art to enhance the quality of such a deflection coil However, it was usually necessary to provide the conductor windings of the deflection coil with a complex and precisely arranged distribution in order to get a deflection coil of good quality. Therefore it was also necessary to make the apparatus for winding the deflection coil both complex and precisely formed.

Such complex and precise structures of the deflection coil and its winding apparatus are relatively expen sive and make it difficult to get uniform deflection coils when the latter are mass produced using several of such winding apparatus.

OBJECTS OF THE INVENTION Accordingly, it is an object of this invention to provide an improved and novel saddle type deflection coil.

It is another object of this invention to provide a novel saddle type deflection coil. the structure or con figuration of which is simplified.

It is a further object of this invention to provide a novel saddle type deflection coil in which the distribution of the conductor windings is simplified.

It is a still further object of this invention to provide a deflection coil winding apparatus of simple structure for winding the improved and novel saddle type deflection coil.

SUMMARY OF THE INVENTION The saddle type deflection coil of this invention has cross sections. taken in planes perpendicular to a first axis corresponding to the longitudinal central axis of the cathode ray tube, which each consist of a pair of half sectional portions symmetrical with reference to a second axis perpendicular to the first axis, and each of the half sectional portions has an outer curved margin formed by an arc of a circle centered on the first axis, an inner margin having a curved part formed by an arc of another circle centered on the first axis and a straight part extending from the curved part parallel with the second axis.

The winding apparatus for producing the saddle type deflection coil according to this invention includes a female member and a male member. Each cross section of the female member. taken on a plane perpendicular to a first axis corresponding to the longitudinal central axis of a cathode ray tube, consists of a pair of half sectional portions symmetrical with reference to a second axis perpendicular to the first axis, and each of the half sectional portions includes inner curved margin formed by an arc of a circle centered on the first axis. Each cross section of the male member. taken on the same plane perpendicular to the first axis. consists of a pair of half sectional portions symmetrical with reference to the second axis, and each of the half sectional portions includes an outer margin having a curved part formed by an arc of another circle also centered on the first axis and a straight part extending from the curved part parallel with the second axis.

This invention may be better understood however when the following detailed description is read in connection with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a simplified side elevational view of a representative deflection coil of the prior art.

FIGS. ZA-ZG are cross sectional views taken on the planes perpendicular to the Z. axis at points Z. Z,. in FIG. 1.

FIG. 3 is a graph showing the distribution of conductor windings at various planes corresponding to FIGS. 2A2G.

FIG. 4 is a partial cross sectional view of a winding apparatus for producing the deflection coil of the prior art.

FIG. 5 is a schematic end elevational view of the deflection coil winding apparatus shown in FIG. 4, with the male and female members of such apparatus being shown in full and broken lines, respectively.

FIG. 6 is a graph to which reference will be made in explaning the distribution of conductor windings of the deflection coil according to the present invention as compared with that of the prior art.

FIG 7 is a partial cross sectional view of a defelection coil according to the present invention.

FIG. 8 is a partial cross sectional view of a deflection coil winding apparatus according to the present invention.

FIG. 9 is a schematic end elevational view similar to that of FIG. 5, but showing the coil winding apparatus of FIG. 8.

FIG. 10 is a simplified perspective view of the male member of the deflection coil winding apparatus according to the present invention.

FIG. 11 is a graph similar to that of FIG. 3, but which shows the distribution of conductor windings of the deflection coil according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1 which shows a typical saddle type deflection coil according to the prior art, it will be seen that the abscissa or Z-axis is parallel with the longitudinal central axis of a cathode ray tube (not shown) of a television receiver, on which the saddle type deflection coil 1 is mounted, and is directed toward the screen of the cathode ray tube. The cross sections of the deflection coil 1 in planes passing through points Z to Z. on the Z-axis and which are perpendicular to theaxis, that is parallel to the ordinate or Y-axis, are shown in FIGS. 2A to 2G, respectively. In each of FIGS. 2A to 2G, the abscissa or X-axis is perpendicular to both the Y-and Z-axes.

It will be seen that each of the cross-section shown in each of FIGS. 2A to 20 consists of a pair of arc-shaped half

sectional portions

5A and 5B which are symmetrical with respect to the Y-axis. The half

sectional portions

5A and 5B are filled with a large number of conductor windings directed from rear to front of the sheet of FIGS. 2A to 2G. If the inner radius of the arc-shaped half

sectional portions

5A and 5B is taken as Rin. its angle from the left side of the X-axis is taken as 8 and the thickness of each of the section 5A and 58 on the extension of the radius Rin is taken. as d, the thickness d is generally selected to satisfy the following expression:

d D cos"9 In the above expression, as the plane of the section is moved from point Z to point Z that is, from FIG. 2A to FIG. 2G, the value of the factor D gradually becomes smaller, while the value of the factor n gradually become greater. That is, with the prior art saddle type deflection coil the thickness d is precisely controlled by the factors D. n and 6. Such a precise control is necessary to compensate for or correct a raster distortion such as a so-called pincushion distortion, misconvergence and so on ofthe cathode ray tube in beam deflection. Since such a compensation or correction is well known in the art, its detailed description will be omitted for the sake of brevity.

The relationships between the thickness d and the angle 6 for each of the cross sectional portions A and SB shown in FIGS. 2A to 2G are shown by the curves 2A to 2G on FIG. 3.

If the inner and outer curves of the half cross sectional portions 5A shown in FIGS. 2A to 2G are taken as p, and p and the inner and outer curves of the right half cross sectional portions 58 shown in FIG. 2A to 2G are taken as q, and q it can be said that the saddle type deflection coil 1 shown in FIG. I is restricted in the distribution of conductor windings by the curved inner surface which is formed by a number of continuous curves p,, the curved outer surface which is formed by a number of continuous curves p the curved inner surface which is formed by a number of continuous curves q and of the curved outer surface which is formed by a number of continuous curves q In order to obtain the above inner and outer surfaces which define the distribution of conductor windings, a coil winding apparatus 10 used in the prior art has a half cross sectional configuration as shown on FIG. 4 at the plane which corresponds to the poane of the view on FIG. 2C. The coil winding apparatus 10 consists of a male member 10A with a predetermined outer sur face N and of a female member 10B with a predetermined inner surface M opposing the outer surface N. The outer surface N of the male member 10A is formed of a curved surface having a radius r extending from a center or point S, at the intersection of the X-Y axes in FIG. 4, while the inner surface M of the female memher 108 is formed of a curved surface having a radius R extending from a center or point S which is spaced from the point 5, by Ar in the left direction of the X- axis and Ay in the downward direction of the Yaxis. Thus, between the male and female members 10A and 108 there is formed a cavity or clearance 12 whose thickness dis reduced as the winding angle 6 increases. Therefore, if conductor windings are wound to fill the cavity 12, a coil with the cross section similar to that shown in FIG. 2C is obtained.

FIG. 5 shows a schematic or simplified end elevational view of the coil winding apparatus 10 which is used to form the deflection coil 1 having the cross sections shown in FIGS. 2A to 2G. In FIG. 5, the male member 10A is shown by a solid line, while the female member 108 is shown by a broken line It will be seen that the outer surface N of male member 10A is defined by a series of curves N -N The radius r of the outer curves N -N which form the outer surface N, has its center at the crossing point 8, and increases gradually anti cciiunuously in the direction perpendicular to the plane of the sheet of the drawing (from rear to front of the Z-axis in FIG. I). In short, the radius r is expressed by a function of Z and the minimum inner curve N is determined by the minimum value r of the radius r, while the maximum inner curve N is determined by the maximum value UI the radius r. If outer curves with the radius from r to r are formed continuously in the Zaxis direction. an outer surface N which is changed in accordance with a curve of second degree is obtained. The curve of second degree is predetermined to coincide with the curved surface of the funnel portion of the cathode ray tube. The X- and Y-axes are used as reference or center axes for forming the male member 10A.

The inner surface M of the female member 108 is shown to be formed of a series of curves M M The radius R of the minimum inner curve M has its center points 5 and S deviated from the Y- and X-axes by A r and A and the radius R of the maximum inner curve M has its center points S and S deviated by Ar and Ay from the points S and S to form the inner curve with the radius R Thus, the inner surface M is formed of a series of inner curves M,-M whose radii have their centers changed gradually and continuously from the point S to the point S and from the point S to the point S Accordingly, when the female member 108 is worked, it is necessary to shift the working reference or center axis.

In using coil winding apparatus 10, the latter is rotated in such a manner that conductor windings are supplied to the air gap or cavity 12 formed between the outer surface N ofthe male member 10A and the inner surface M of the female member 108, and the rotation of the coil winding apparatus 10 is continued till the cavity 12 is filled with the conductor windings. Thus, there is obtained the deflection coil 1 with the cross sections shown in FIGS. 2A to 2G. The driving mechanism for the coil winding apparatus 10 is well known in the art, so that its description will be omitted for the sake of brevity.

When the electron beam of the cathode rays tube is deflected by the deflection coil 1 formed as described above, it is known, that a substantial improvement in the various raster distortions such as misconvergence, pincushion distortion or the like, requires relatively great difference betweem the distribution of conductor windings of the deflection coil 1 at its rear and front ends considered in the Z-axis direction or the longitudinal central axis of the cathode ray tube. However, in order to greatly change the distribution of conductor windings, it is required that the working reference or center axis used in the production of the female member 108 be shifted through relatively large distances, as described in connection with FIG. 5. Accordingly, difficulties are encountered in forming the inner surface of the female member 108. Therefore, in order to manufacture the deflection coil 1 which has a great change in the distribution of conductor windings between its front and rear ends it is necessary to either manually shape the inner surface M of the respective female member 1013 or to form such surface with a computer controlled machine. In either case, the coil winding apparatus 10 is expensive and, if shaped manually, it is difficult to mass produce large numbers of the deflection coils using a member of the coil winding apparatus as achievement of the same contours on the manually shaped inner surfaces of such apparatus is very difficult. As a result, the above mentioned misconvergence or distortion can not be sufficiently improved by the previously existing deflection coils.

An embodiment of the present invention will be now described with reference to FIGS. 6-11.

Since the prior art deflection coil 1 is selected to have the thickness to winding angle relation of d=Dcs 6, the thickness distribution of the deflection coil 1 at the cross section shown in. for example, FIG. 2C, is shown in FIG. 6 by a solid line curve 21. However, a novel deflection coil 20 according to the present invention, which will be described in detail below and which has a typical section as shown on FIG. 7, is provided with a cross sectional area the same as that of the prior art, but with the distribution of conductor windings within such area being entirely from that represented by the curve 21, as follows. With the present invention, the distribution of the conductor windings is decreased in thickness up to a certain winding angle 60, but is constant in thickness at winding angles exceeding the angle 6 as is indicated in FIG. 6 by a dotted line curve 22. The cross section of the deflection coil 20 according to the present invention shown in FIG. 7 corresponds to that of the prior art coil 1 shown on FIG. 2C.

The cross section shown in FIG. 7 is referenced to the X-and Y-axes as in the case of FIGS. 2A to 2G. The deflection coil 20 consists of a pair of half section portions 23A and 233 which are defined by outer and

inner margins

24 and 25. The outer margin 24 is curved and is formed by a first arc with the radius R whose center is at the intersection O of the X and Y axes. The inner margin 25 is formed with a straight part 250 parallel to the Y-axis between the

values

0 and 6,, of the winding angle 0, and a curved part 25b formed by an arc with the radius r whose center is at the intersection 0 over the winding angle greater than 0 In this case, the angle 0,, and the radii r and R are so selected that the areas of the half

sectional portions

23A and 23B are equal to those of the half sectional portions A and 513 shown in FIG. 2C.

FIG. 8 shows in cross section a coil winding apparatus 30 according to the present invention which is suitable for making the deflection coil with the section shown in FIG. 7. In FIG. 8, reference numeral 30A indicates a male member which has an outer surface 26 corresponding to the inner margin shown in FIG. 7, and reference numberal B indicates a female member which has an inner surface 27 corresponding to the outer margin 24 shown in FIG. 7. As shown in FIG. 8, the inner surface 27 of the female member 3013 is formed as an arc with the radius R thereof having its center at the center 0 of the are which is used for defin ing the curved part by the outer surface 26 of the male member 30A.

FIG. 9 is a simplified or schematic end elevational view of the coil winding apparatus 30. In FIG. 9, the male member 30A is shown by a solid line, while the female member 308 is shown by a broken line. The outer surface 26 of the male member 30A and the inner surface 27 of the female member 308 are formed continuously in the direction of the Z-axis which corresponds to the longitudinal central axis of the cathode ray tube as mentioned above. and their centers are positioned at the intersection point 0 of the Y- and X- axes.

As may be apparent from a comparsion of FIG. 9 with FIG. 5, the female member 303 of the coil winding apparatus 30 of the present invention is simplified as compared with the female member 108 of the prior art coil winding apparatus 10. More specifically, with the prior art female member 108 the center or reference point for forming the inner surface M must be shifted by Ax and Ay from the intersection O of axes X and Y, while with the female member 303 of the present invention the center point of the inner surface 27 with respect to the Y-and X-axes coincides with the center point 0. In other words, when the female member 30b of the present invention is manufactured, there is no need to move the reference or center point with respect to the Y-and X-axes. Hence, the female member 308 can be obtained easily and precisely.

The configuration or contour changes of the outer surface 26 of the male member 30A and the inner surface 27 of the female member 30B will now be described. The outer and

inner surfaces

26 and 27 are widened gradually in the direction toward the front end of the respective coil in accordance with the configuration of the funnel portion of the cathode ray tube. The radius R of the inner surface 27 of the female member 308 is increased gradually from R, to R while the radius r of the part 25b outer surface 26 of the male member 30A is increased gradually from r, to r to form the curved part 25b. In this case, the straight part 250 is formed in accordance with the

angle range

0, 6 which increases gradually in the Z-axis direction. Thus, the main portion of the male member 30A is formed as shown in FIG. 10, in which reference numbered 29 indicates a concave portion which may engage with a convex portion 31 (FIG. 9) of the female member 30B. The distribution of conductor windings of the deflection coil 20 formed by the coil winding ap paratus 30 consisting of the male and

female members

30A and 30B is shown in FIG. 11. In order to be compared with the prior art distribution shown in FIG. 3, FIG. 11 shows the distribution at the cross sections of the deflection coil 20 corresponding to those of FIGS. 2A to 2G, and the curves corresponding to those of FIG. 3 are identified by the same reference numerals but with primes added thereto, for example, as at 2A and 2G.

As described above, in accordance with the present invention the deflection coil 20 is formed with the typical cross section shown in FIG. 7 and in which the cross section area is selected to be the same as that of the well known D cos"0 winding. Thus, the distribution of the conductor windings of the present invention becomes similar to that of the prior art and the similar deflection characteristics can be obtained.

Further, with the present invention the coil winding apparatus 30, which is used to manufacture the deflection coil 20, is so formed that the center or working axes of the inner and

outer surfaces

26 and 27 of the male and

female members

30A and 30B of the coil winding apparatus 30 can be fixed at the intersection of the reference X-and Y-axes. As a result, the inner surface 27 of the female member 30B is, especially, easily and precisely formed. Further, when the distortion such as the pincushion, misconvergence or the like is to be improved, it is sufficient to merely increase the ratio between the

angles

6 and 8,, It will be apparent that, when a plurality of deflection coils 20 are made, there is no scattering in deflection characteristics, that is, a plurality of deflection coils 20 which have the same characteristics can be easily manufactured.

It will be apparent that many modifications and variations can be effected in the above described embodiment of the invention by one skilled in the art'without departing from the spirit and scope of the invention as defined in the appended claims.

I claim as my invention:

1. A saddle type deflection coil for a cathode ray tube having cross-sections in planes perpendicular to a first axis corresponding to the longitudinal central axis of said cathode ray tube and each of which consists of a pair of half sectional portions substantially symmetrical with reference to a second axis lying in the respective plane and being perpendicular to said first axis, each of said half sectional portions of each cross-section including:

a. an outer curved margin defined by an arc ofa circle with a center at a point on said first axis;

b. an inner margin having a curved part formed by an arc of another circle with a center at said point on said first axis and a straight part extending parallel with said second axis from said curved part; and

c. a pair of connecting margins between the adjacent ends of said outer and inner margins.

2. A saddle type deflection coil according to claim I, wherein the diameters of said circles of which arcs define said outer curved margin and said curved part of the inner margin increase gradually in accordance with the positioning of the respective plane along said first axis from the rear to the front of the deflection coil.

3. A saddle type deflection coil according to claim 2, wherein the length of said straight part of the inner margin is gradually increased with the increase in the diameter of said circle having the arc which defines said curved part of the inner margin.

4. A saddle type deflection coil according to claim 1, wherein each of said cross-sections has an area equal to that of Dcos"6 deflection coil at a corresponding location along the latters longitudinal central axis.

Claims

1. A saddle type deflection coil for a cathode ray tube having cross-sections in planes perpendicular to a first axis corresponding to the longitudinal central axis of said cathode ray tube and each of which consists of a pair of half sectional portions substantially symmetrical with reference to a second axis lying in the respective plane and being perpendicular to said first axis, each of said half sectional portions of each cross-section including: a. an outer curved margin defined by an arc of a circle with a center at a point on said first axis; b. an inner margin having a curved part formed by an arc of another circle with a center at said point on said first axis and a straight part extending parallel with said second axis from said curved part; and c. a pair of connecting margins between the adjacent ends of said outer and inner margins.

2. A saddle type deflection coil accOrding to claim 1, wherein the diameters of said circles of which arcs define said outer curved margin and said curved part of the inner margin increase gradually in accordance with the positioning of the respective plane along said first axis from the rear to the front of the deflection coil.

4. A saddle type deflection coil according to claim 1, wherein each of said cross-sections has an area equal to that of Dcosn theta deflection coil at a corresponding location along the latter''s longitudinal central axis.