Patents by Inventor Weiguo Zhang

Weiguo Zhang 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).

  • Publication number: 20030181040
    Abstract: An apparatus of the invention has a closable chamber that can be sealed and is capable of withstanding an increased pressure and high temperature. The chamber contains a substrate holder that can be rotated around a vertical axis, and an edge-grip mechanism inside the substrate holder. The deposition chamber has several inlet ports for the supply of various process liquids, such as deposition solutions, DI water for rinsing, etc., and a port for the supply of a gas under pressure. The apparatus is also provided with reservoirs and tanks for processing liquids and gases, as well as with a solution heater and a control system for controlling temperature and pressure in the chamber. The heater can be located outside the working chamber or built into the substrate holder, or both heaters can be used simultaneously. Uniform deposition is achieved by carrying out the deposition process under pressure and under temperature slightly below the boiling point of the solution.
    Type: Application
    Filed: March 22, 2002
    Publication date: September 25, 2003
    Inventors: Igor Ivanov, Jonathan Weiguo Zhang, Artur Kolics
  • Patent number: 6603990
    Abstract: A magnetic resonance imaging (MRI) method is disclosed for generating and identifying water and fat separated MR images. Image data is first acquired to obtain two echo images with the water and fat signals orthogonal in the first echo image, and parallel/anti-parallel in the second echo image. The effect of background field inhomogeneties are removed, and water and fat images are separated from each other. The separated water and fat images are identified according to the difference of their precessing frequencies.
    Type: Grant
    Filed: August 10, 2001
    Date of Patent: August 5, 2003
    Assignee: Toshiba America MRI, Inc.
    Inventors: Weiguo Zhang, David M. Kramer
  • Publication number: 20030109781
    Abstract: An improved magnetic resonance imaging (MRI) methodology wherein an abbreviated MRI sequence is carried out to generate sequence diagnostic parameters. The sequence diagnostic parameters have a fixed relationship to certain sequence-conditioning parameters, and are used for calculating characteristic values of the sequence-conditioning parameters. More particularly, the read out gradient pulse sequence is modified in accordance with the calculated characteristic values of the sequence-conditioning parameters. The modified read out gradient pulse sequence is then incorporated into the MRI pulse sequence used for obtaining a diagnostic image. The methodology has particular application in so called ultra fast MRI systems which include echo-planar imaging (EPI) systems and echo-volume imaging (EVI) systems.
    Type: Application
    Filed: December 11, 2001
    Publication date: June 12, 2003
    Inventor: Weiguo Zhang
  • Publication number: 20030060697
    Abstract: A magnetic resonance imaging (MRI) method is disclosed for generating and identifying water and fat separated MR images. Image data is first acquired to obtain two echo images with the water and fat signals orthogonal in the first echo image, and parallel/anti-parallel in the second echo image. The effect of background field inhomogeneties are removed, and water and fat images are separated from each other. The separated water and fat images are identified according to the difference of their precessing frequencies.
    Type: Application
    Filed: August 10, 2001
    Publication date: March 27, 2003
    Inventors: Weiguo Zhang, David M. Kramer
  • Patent number: 6459922
    Abstract: A post data-acquisition magnetic resonance imaging (MRI) method is disclosed for generating water/fat separated MR images wherein the resultant contrast in water-only or fat-only images is made adjustable under operator control. Image data is first obtained using a single-scan three-point Dixon MRI scan sequence having a specific nuclear magnetic response (NMR) signal echo time, TE. The timing of read-out gradient pulses during the MRI imaging scan sequence is selected according to the chemical-shift difference between water and fat signals so that the water and fat NMR signals evolve between them an angle of &pgr; radians during an inter-echo time &Dgr;TE. Water/fat separated images of variable contrast are then produced by reprocessing the acquired image data using different operator selected values for the contrast echo time (newTE) when correcting for relaxation.
    Type: Grant
    Filed: March 30, 1999
    Date of Patent: October 1, 2002
    Assignee: Toshiba America MRI, Inc.
    Inventor: Weiguo Zhang
  • Patent number: 6448773
    Abstract: A method and apparatus is disclosed for measuring and compensating the effects of eddy currents induced during NMR imaging operations. A cubic or cylindrical sample is placed in the imaging volume of a MRI system at a position centrally located with respect to the main magnetic field and oriented with its longitudinal axis parallel to a desired measuring direction. A magnetic field gradient pulse is applied for inducing eddy currents as well as for generating a slice-selective spin-echo signal. The spin-echo signal is acquired immediately after the termination of each eddy-current inducing gradient pulse. Two slices are selected along the desired measurement direction at symmetrical equal distance from the center of the main magnetic field. Two spin-echo signals are acquired for each slice with the polarity of the eddy-current inducing gradient pulse reversed between the two echo signals.
    Type: Grant
    Filed: February 24, 2000
    Date of Patent: September 10, 2002
    Assignee: Toshiba America MRI, Inc.
    Inventor: Weiguo Zhang
  • Publication number: 20010054898
    Abstract: A magnetic resonance imaging method and apparatus gathers NMR image data over a sequence of measurement cycles. First magnetic gradient pulses are superimposed on a nominally static magnetic field to selectively address NMR RF excitations for at least one predetermined volume and second magnetic gradient pulses are superimposed on the static magnetic field at other times in a measurement cycle. At least one further of the measurement cycles is performed during which at least one of the second gradient pulses is omitted so as to produce calibration data representative of the magnetic field then existing in the predetermined volume. The calibration data is used to produce MRI data compensated for phase angle errors which otherwise would be present due to undesirable changes with respect to time in the magnetic field actually present in said predetermined volume.
    Type: Application
    Filed: March 10, 1999
    Publication date: December 27, 2001
    Inventors: ANDREW LI, DAVID M GOLDHABER, WEIGUO ZHANG, HECTOR AVRAM, DAVID M KRAMER
  • Patent number: 6263228
    Abstract: A method and apparatus for producing water-dominant and fat-dominant MR signal data for use in constructing separate images from single-scan single-point Dixon MRI sequences is disclosed. The effects of field inhomogeneities are removed by quantitating the signal phase by taking the argument of the MR signal multiplied by itself. A region-growing algorithm guided by a polynomial model is used to unwrap the phase which is then used to separately generate water-pixel data and fat-pixel data for producing separate images. The invention can be used for constructing images from both 2-D and 3-D spin-echo and/or field-echo acquisitions.
    Type: Grant
    Filed: August 27, 1998
    Date of Patent: July 17, 2001
    Assignee: Toshiba America, MRI, Inc.
    Inventors: Weiguo Zhang, David M. Kramer, Andrew Li
  • Patent number: 6147492
    Abstract: A magnetic resonance imaging (MRI) method and apparatus is disclosed for quantitating water and fat content of tissues using nuclear magnetic resonance (NMR) image data of the tissues and for producing an images indicative of the fat and water fractions of the total water and fat content of the tissues. To reduce the overall scanning time, a quadruple field-echo imaging scan sequence is used to acquire the image data. Each imaging sequence comprises an initial slice-selective RF excitation pulse followed by four magnetic field read-out gradient pulses and the acquisition of four separate field-echoes. Each field-echo is generated through the controlled timing and polarity of an applied read gradient. The period of time between field-echoes (T) is selected according to the chemical-shift difference between water and fat signals so that the two signals develop between them an angular phase difference of .pi. radians (180.degree.) during the inter-echo time.
    Type: Grant
    Filed: October 28, 1998
    Date of Patent: November 14, 2000
    Assignee: Toshiba America MRI, Inc.
    Inventors: Weiguo Zhang, Joseph W. Carlson
  • Patent number: 6114853
    Abstract: Nuclear magnetic resonance (NMR) methods are invented which allow for quantification of sequence-induced B.sub.0 oscillation in magnetic resonance imaging (MRI). The techniques can be used to study any system malfunction which induces sequence-synchronized phase oscillation of the MR signals. When the oscillation is spatially uniform, methods are also developed to correct the acquired NMR data for minimizing the effects of the oscillation.
    Type: Grant
    Filed: June 25, 1997
    Date of Patent: September 5, 2000
    Assignee: Toshiba America MRI, Inc.
    Inventor: Weiguo Zhang
  • Patent number: 5947802
    Abstract: A shuttle system for transferring a semiconductor wafer from a receiving station to a horizontal-oriented head drive of a wafer polishing machine includes a linear horizontal rail extending from a first position to a second position; a wafer transfer assembly adjacent to the first position; a wafer conveying assembly movable along the rail from adjacent the first position to adjacent the second position; and wherein the wafer conveying assembly includes a vertically movable and radially movable gripper for gripping peripheral edges of a wafer to be transferred and conveyed from the transfer assembly to the head drive. The transfer assembly includes a transfer receiver for receiving an unpolished wafer from a cassette which receiver is movable to the second position where the gripper is movable to edge-grip the received unpolished wafer. The gripper includes a series of radially movable segments having edge-contacting fingers depending therefrom for gripping the wafer edges.
    Type: Grant
    Filed: November 5, 1997
    Date of Patent: September 7, 1999
    Assignee: Aplex, Inc.
    Inventors: John Weiguo Zhang, H. Alexander Anderson
  • Patent number: 5909119
    Abstract: A method and apparatus for obtaining three MRI image data in a single data acquisition TR interval for use in constructing separate water and fat images by appropriate processing of the three images data is disclosed. The three image data are obtained in one exemplary embodiment by sandwiching a spin echo between two field echoes. The invention can also be used for multiple-echo and multiple-slice 3D scans.
    Type: Grant
    Filed: December 18, 1996
    Date of Patent: June 1, 1999
    Assignee: Toshiba America MRI, Inc.
    Inventors: Weiguo Zhang, David M. Kramer, David M. Goldhaber, Ching Yao, Hsu Chang
  • Patent number: 5652514
    Abstract: Methods and apparatus for correcting image artefacts caused by variations in the main magnetic field of an MRI system are disclosed, particularly for MRI with steady-state spin precession. For field correction in MRI with steady-state spin precession, the effects of the field changes can be corrected by quantifying the time course of the field drifts by repeated acquisition of the zero k-space lines. The change in the phase between consecutive zero k-space lines is used as an indicator of field variation and for correction of associated image artifacts. By using for field correction the zero k-space lines acquired using the imaging sequence itself, the steady-states of spin precession are undisturbed throughout the MRI data acquisition.
    Type: Grant
    Filed: March 25, 1996
    Date of Patent: July 29, 1997
    Assignee: Toshiba America MRI, Inc.
    Inventors: Weiguo Zhang, David M. Kramer, David M. Goldhaber