Patents by Inventor Jozo Shimizu

Jozo Shimizu 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: 4946374
    Abstract: A magnetic recording medium which comprises a first magnetic layer on a base and a second magnetic layer thereon, the first magnetic layer containing magnetic particles having an average particle length (long axis diameter) of 0.4 to 0.7 .mu., the second magnetic layer containing magnetic particles having an average particle length (long axis diameter) of 0.25 to 0.35 .mu., the coercive force of which being 370 to 460 oersteds, and the ratio of coercive force of the upper or second layer to that of the lower or first magnetic layer being 1.05/l to 1.5/l. The magnetic recording medium has excellent sensitivity and frequency characteristics at entire frequency bands with less noise.
    Type: Grant
    Filed: December 21, 1988
    Date of Patent: August 7, 1990
    Assignee: Hitachi Maxell, Ltd.
    Inventors: Satoru Yamaguchi, Jozo Shimizu, Kozaburoh Satoh, Haruo Andoh
  • Patent number: 4722863
    Abstract: A magnetic recording medium comprising a substrate and a magnetic layer coated thereon, the magnetic layer containing magnetic powder, a resinous binding agent and at least one sorbic acid compound selected from the group consisting of sorbic acid and derivatives and metal salts thereof, such that the magnetic powder is well dispersed in the magnetic layer and which has improved electrical properties.
    Type: Grant
    Filed: April 4, 1985
    Date of Patent: February 2, 1988
    Assignee: Hitachi Maxell, Ltd.
    Inventors: Toshihiko Tanabe, Jozo Shimizu, Kozaburo Sato
  • Patent number: 4624883
    Abstract: A magnetic recording medium which comprises a first magnetic layer on a base and a second magnetic layer over the first magnetic layer, the second magnetic layer containing magnetic particles having an average particle length (long axis diameter) of not more than 0.35.mu. , with a coercive force of from 660 to 760 oersteds, and the ratio of the coercive force of the upper or second magnetic layer to that of the lower or first magnetic layer being 1.1/1 to 1.6/1. The resulting magnetic recording medium has excellent sensitivity and frequency characteristics over the entire frequency bands with less noise.
    Type: Grant
    Filed: March 19, 1984
    Date of Patent: November 25, 1986
    Assignee: Hitachi Maxell, Ltd.
    Inventors: Satoru Yamaguchi, Kozaburoh Satoh, Jozo Shimizu, Haruo Andoh
  • Patent number: 4349608
    Abstract: A magnetic recording medium improved in lubricity and abrasion resistance, which comprises a base material and a magnetic layer provided thereon, said magnetic layer comprising magnetic particles and a binder, characterized in that said magnetic layer further comprises at least one silicone compound of the formula: ##STR1## wherein X is the same or different and --A--COOH, --A--OH, ##STR2## or --A--NH.sub.2 in which A is a divalent hydrocarbon group having not more than 26 carbon atoms, Y and Y' are each --X or --CH.sub.3, p is an integer of 0 to 1,000 and q is an integer of 1 to 500 but p+q is not more than 1,000 in an amount of 0.1 to 5% by weight based on the weight of the magnetic particles in the magnetic layer.
    Type: Grant
    Filed: August 19, 1981
    Date of Patent: September 14, 1982
    Assignee: Hitachi Maxell, Ltd.
    Inventors: Jozo Shimizu, Satoru Yamaguchi, Shigeo Aoyama
  • Patent number: 4275113
    Abstract: Magnetic recording medium comprising a support or carrier sheet and a magnetic layer formed on one side of the support, wherein there is provided between the support and the magnetic layer at least one intermediate layer of resinous polymeric material including particles of carbon black having large specific surface area and high oil absorption so that electrification of the recording medium can be prevented with good adhesiveness of the magnetic layer to the support.
    Type: Grant
    Filed: October 17, 1979
    Date of Patent: June 23, 1981
    Assignee: Hitachi Maxell, Ltd.
    Inventors: Osamu Saito, Jozo Shimizu, Hiroshi Zaitsu