Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1999-06-30
2001-11-06
Young, Lee (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S605000, C029S606000
Reexamination Certificate
active
06311389
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a coil apparatus such as gradient magnetic field coil apparatus of magnetic resonance imaging apparatus, and a method of manufacturing the same.
This application is based on Japanese Patent Application No. 10-186463, filed Jul. 1, 1998, the content of which is incorporated herein by reference.
In a magnetic resonance imaging apparatus, a gradient magnetic field coil is located inside of a magnet (super-conductive magnet, ordinary conductive magnet, permanent magnet) for generating a static magnetic field. The gradient magnetic field coil is usually composed of three sets of coils called Gx, Gy, Gz coils, and a gradient magnetic field differing in the intensity linearly in each orthogonal direction of x-, y-, and z-axes. Herein, usually, the z-axis direction is the axial direction of the object, and the lateral direction (width direction) of the object is the x-axis direction, and the depth direction (thickness direction) of the object is the y-axis direction.
The gradient magnetic field has a linear inclination in the static magnetic field (principal magnetic field) for the purpose of arbitrarily determining the imaging section, or adding the position information to the RF signal from the object. A required performance of the gradient magnetic field coil includes the linearity of the gradient magnetic field in order to give accurate position information. The shape of the gradient magnetic field coil differs with the direction of the static magnetic field, and direction of inclination, but usually a pair of loop coils are used as Gz coil, and four saddle coil sets are generally used as Gx and Gy coils. Actually, moreover, outside of the gradient magnetic field coil, a shield coil of substantially the same shape is provided in order to prevent leak of magnetic field from the gradient magnetic field coil to outside.
The shape of the saddle coil is part of the surface of columnar or elliptical columnar form, and hence it is hard to manufacture. In a conventional manufacturing method of saddle coil, a coil winding of a specified pattern is cutout from a flat conductor thin plate, an insulating sheet is adhered to the surface of the coil winding, and it is pressed against a pressing die to curve, thereby forming a saddle coil (for example, U.S. Pat. No. 5,349,744). As the coil winding cutting-out method, a wire cutter, laser, or water jet cutter may be used, or a method of blanking a thin plate to a die having the coil shape groove, or a method of etching may be employed.
In such conventional methods, commonly, since a coil winding is cut out from a flat conductor plate, and then curved, the manufacturing process is complicated, and it takes many days, but the manufacturing error cannot be prevented. Yet, the winding extending in the cylindrical direction of the cylinder is curved, but the winding extending in the axial direction of the cylinder is not curved. Accordingly, gradient magnetic field having linearity of high precision cannot be generated. Further, if a thick conductor plate is required, curling in peripheral direction may be formed in the process of curving the coil winding, and it is hard to process into a desired shape.
Thus, the conventional manufacturing method of gradient magnetic field coil (such as called saddle coil) is complicated in manufacturing process, long in manufacturing time, and not free from manufacturing error.
BRIEF SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a manufacturing method capable of manufacturing a coil of desired shape in a short time and at high precision, and a coil apparatus using such coil.
According to the present invention, there is provided a manufacturing method of a coil comprising:
attaching a preliminarily curved metal plate on a jig;
cutting the metal plate along the contour of a spiral coil winding;
removing the unnecessary plate portion other than the coil winding of the metal plate from the metal plate and leaving only the coil winding on the jig;
connecting a support on the coil winding; and
removing the coil winding from the jig.
According to the present invention, there is provided another manufacturing method of a coil comprising:
connecting a support on an inner surface of a preliminarily curved metal plate;
attaching the support on a jig;
cutting the metal plate along the contour of a spiral coil winding; and
removing the unnecessary portion other than the coil winding of the metal plate from the support, and leaving only the coil winding on the support.
According to the present invention, there is provided a coil apparatus comprising first and second coil windings, being connected to generate a desired magnetic field, wherein the first and second coil windings are mutually connected with at least two electrical connections.
According to the present invention, there is provided another coil apparatus comprising a bobbin having a partial shape of cylindrical form, and a coil winding mounted on the bobbin, the coil winding including at least one of notch, protrusion and hole for positioning when mounting on the bobbin.
According to the present invention, there is provided a still another coil apparatus comprising a bobbin having a partial shape of cylindrical form, and a coil winding mounted on the bobbin, wherein both sides of a part of coil winding along an axial direction of the bobbin is orthogonal to a curved surface of the bobbin.
According to the present invention, there is provided a gradient coil apparatus comprising:
a bobbin having a partial shape of cylindrical form;
a primary coil, mounted on the bobbin, for generating a gradient magnetic field, the primary coil including coil windings having a partial shape of cylindrical form and arranged in a matrix, each of the coil windings having the same coil pattern, and innermost ends of two coil windings in the same row being connected through a conductor.
According to the present invention, there is provided an actively shielded gradient coil apparatus comprising:
a bobbin having a partial shape of cylindrical form;
a primary coil, mounted on the bobbin, for generating a gradient magnetic field, the primary coil including coil windings having a partial shape of cylindrical form and arranged in a matrix, each of the coil windings having the same coil pattern, and innermost ends of two coil windings in the same row being connected through a conductor; and
a shield coil, mounted on the primary coil, for generating a magnetic field preventing leak of magnetic field from the primary coil, the shield coil including coil windings having a partial shape of cylindrical form and arranged in a matrix, each of the coil windings having the same coil pattern, and innermost ends of two coil windings in the same row being connected through a conductor.
According to the present invention, since the coil winding is formed by cutting a preliminarily curved metal plate, the manufacturing process is simple, and a coil having a desired surface shape can be manufactured in a short time.
According to the present invention, since the coil winding has notch, protrusion or hole for positioning, the coil winding can be fixed to the bobbin with high precision, thereby enabling to generate a magnetic field in a desired distribution pattern with high precision.
According to the present invention, portions of the coil winding which along an axial direction of the bobbin is curved and the side faces of that portion are orthogonal to a plane of curvature of the bobbin. Therefore, it is also possible to generate a magnetic field in a desired distribution pattern with high precision.
Additional objects and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention.
The objects and advantages of the present invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
REFERENCES:
patent: 3911716
Sakakura Yoshitomo
Uosaki Yasuhiro
Watanabe Kunio
Yamashita Masatoshi
Kabushiki Kaisha Toshiba
Kim Paul D.
Nixon & Vanderhye P.C.
Young Lee
LandOfFree
Gradient magnetic coil apparatus and method of manufacturing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gradient magnetic coil apparatus and method of manufacturing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gradient magnetic coil apparatus and method of manufacturing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2617116