Patents by Inventor Johannes Overweg

Johannes Overweg has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5235282
    Abstract: In a magnetic resonance apparatus comprising a superconducting magnet system (1) for generating a steady magnetic field there is also included a superconducting shielding coil system (22) in order to compensate for magnetic field variations induced in the magnet by external magnetic flux variations. The shielding coil system (22) comprises coil sections (24) of different diameters.
    Type: Grant
    Filed: November 27, 1991
    Date of Patent: August 10, 1993
    Assignee: U.S. Philips Corporation
    Inventors: Johannes A. Overweg, Gerardus N. Peeren
  • Patent number: 5185575
    Abstract: A high order multipole gradient field generating system in a magnetic resonant imaging apparatus comprises spaced quadrants of windings, the windings of each quadrant generating adjacent fields in each quadrant in opposing relation. The multipole system is located adjacent to a lower order conventional gradient field coil system to shield the region of interest from field aberrations, the multipole system generating a relatively strong local magnetic field adjacent to the coils of the gradient field coil system and a negligible change in field in the region of interest. The multipole system causes a frequency shift of the aberrations in the region of interest which are outside the detection frequency range such that the conventional gradient field system signal is substantially unaffected by the multipole system in the region of interest.
    Type: Grant
    Filed: December 4, 1990
    Date of Patent: February 9, 1993
    Assignee: U.S. Philips Corp.
    Inventor: Johannes A. Overweg
  • Patent number: 4931735
    Abstract: In a magnetic resonance apparatus a system of concentric cylinders of superconductive material maintain an effective steady magnetic field in a measured space within the inner cylinder which field is very homogeneous and is, moreover, very constant in time without requiring a large electric power. In a particular embodiment a magnetic field cylinder produces a strong magnetic field, a stabilization cylinder within the magnetic field cylinder ensures a good homogeneity and stabilization of the effective magnetic field, while a screening cylinder provided outside the magnetic field cylinder reduces the external stray field of the system.
    Type: Grant
    Filed: May 2, 1989
    Date of Patent: June 5, 1990
    Assignee: U.S. Philips Corporation
    Inventors: Johannes A. Overweg, Paul B. Bunk
  • Patent number: 4893083
    Abstract: In a magnetic resonance apparatus a gradient coil system and an r.f. coil are combined so as to form a magnetically, electrically and structurally integrated coil system with current conductors in substantially the same cylinder. Thus, a substantial saving is realized as regards the activation energy required for generating gradient fields as well as for generating r.f. fields and notably r.f. stray-fields are also reduced.
    Type: Grant
    Filed: August 17, 1988
    Date of Patent: January 9, 1990
    Assignee: U.S. Philips Corporation
    Inventors: Johannes A. Overweg, Wilhelmus R. M. Mens
  • Patent number: 4878023
    Abstract: In a magnetic resonance apparatus a gradient coil system in which "return" arc conductors, which contribute substantially less to the gradient field formation because they are situated further outwards radially and/or axially from the center of the system, are positioned to compensate for stray fields of "effective" are conductors, which are more centrally situated and which contribute more substantially to the gradient field formation. Due to both radial and axial displacement of the return arc conductors relative to the effective arc conductors, the measuring space of the apparatus can be conically shaped, so that a higher patient accessibility is achieved or a smaller diameter can be imparted to a central portion.
    Type: Grant
    Filed: August 17, 1988
    Date of Patent: October 31, 1989
    Assignee: U.S. Philips Corporation
    Inventors: Johannes A. Overweg, Cornelis L. G. Ham
  • Patent number: 4878024
    Abstract: In a gradient coil system for a magnetic resonance apparatus arc conductors of notably X coils and Y coils are stacked axially or radially so as to form rigid stacks. The arc conductors are interconnected by means of electrical conductors and the stacks are also interconnected, so that a rigid, self-supporting coil system is obtained. Because the coil system is composed of rigid elements, is comparatively open and does not require a coil former, the production of noise in a magnetic resonance apparatus comprising such a coil system is substantially reduced and field disturbances due to coil deformations are also reduced.
    Type: Grant
    Filed: August 17, 1988
    Date of Patent: October 31, 1989
    Assignee: U.S. Philips Corporation
    Inventors: Johannes A. Overweg, Cornelis L. G. Ham
  • Patent number: 4845432
    Abstract: A magnetic resonance imaging apparatus utilizes a gradient coil system with different arc angles for different arc conductors of the essentially saddle-shaped coil elements of the magnet. As result, the arc conductors can be oriented nearer to the radial symmetry plane so that not only the spatial field homogeneity in an active zone is maintained or improved, but also the efficiency of the gradient magnet system is substantially increased and the power stored in the coil is reduced, thus enabling faster switching.
    Type: Grant
    Filed: December 1, 1987
    Date of Patent: July 4, 1989
    Assignee: U.S. Philips Corporation
    Inventor: Johannes A. Overweg