Patents by Inventor Robert Douglas Hempstead

Robert Douglas Hempstead 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: 4103315
    Abstract: In thin film magnetic transducers, e.g., inductive or magnetoresistive recording heads, at least a pair of layers of a ferromagnetic material and an antiferromagnetic material are deposited upon one another and exchange coupled to retain a unidirectional bias in the plane of the ferromagnetic material. When multiple pairs of layers are used, they are separated by layers of nonmagnetic material. In some cases, successive pairs of layers of material with unidirectional bias have their directions of bias pointing in opposite directions. The domain walls in the layers of material are minimized by this technique.
    Type: Grant
    Filed: June 24, 1977
    Date of Patent: July 25, 1978
    Assignee: International Business Machines Corporation
    Inventors: Robert Douglas Hempstead, Sol Krongelb, Daniel Andrew Nepela, David Allen Thompson, Erich Philipp Valstyn
  • Patent number: 4049522
    Abstract: Iron-silicon is sputtered onto a substrate to be used for a magnetic recording head from a target containing 4% to 7% of silicon with a substrate bias between -2.5 and -60 volts, anode-cathode spacing of about 1/2 to about 2 inches, a deposition rate of greater than 150A/min, a substrate temperature above 250.degree. C, an argon pressure above 10 microns, and a single film thickness greater than 0.4 micron, a laminated film thickness greater than 0.05 micron, and R.F. input power above 8 watts/in.sup.2.
    Type: Grant
    Filed: February 26, 1976
    Date of Patent: September 20, 1977
    Assignee: International Business Machines Corporation
    Inventors: Norman George Ainslie, Robert Douglas Hempstead, Swie-In Tan, Erich Philipp Valstyn
  • Patent number: 4024489
    Abstract: A magnetoresistive permalloy film is deposited upon a substrate and coated with a separating layer composed of titanium or a similar high resistivity, conductive material. A soft biasing layer of a material such as permalloy or a hard biasing material such as cobalt chromium is deposited upon the separating layer to complete a sandwich. All layers are coextensive in outline because their outlines are formed by a single etching step.
    Type: Grant
    Filed: November 18, 1975
    Date of Patent: May 17, 1977
    Assignee: International Business Machines Corporation
    Inventors: Christopher Henry Bajorek, Robert Douglas Hempstead, Sol Krongelb, Ashok Frank Mayadas