Patents by Inventor Chao N. Liu

Chao N. Liu 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: 4142175
    Abstract: A pressure sensing device having applicability as a simple pressure sensor and which is particularly adapted for use as a pen in a Signature Verification System, said device including a unique mounting structure for the pressure sensing stylus by flexible support means mounted on a substantially rigid base. The support means has a pressure sensing element mounted thereon. The flexible support means comprises two spaced members so disposed that their deflections and the output of the pressure sensing element are substantially independent of the angle of pressure on the stylus. In the special purpose embodiment useful for Signature Verification the stylus comprises a pen and the device further includes two orthogonally disposed accelerometers for sensing accelerations of said pen during the writing of a signature.
    Type: Grant
    Filed: June 12, 1978
    Date of Patent: February 27, 1979
    Assignee: International Business Machines Corporation
    Inventors: Noel M. Herbst, Chao N. Liu, Hugo A. Panissidi
  • Patent number: 4128829
    Abstract: Method and apparatus are disclosed for verifying a sample signature based on comparison of the dynamics of a reference and a sample signature. More particularly, second derivative values of pen displacements (i.e. acceleration) and continuous pressure pattern signals are periodically sampled for both a reference and sample signature and a comparison of these second derivative values and pressure patterns is made. To effect the comparisons the two groups (reference and sample) of both second derivative and pressure pattern signals are segmented and corresponding segments are individually correlated. Successive comparisons of the same segment pairs are performed utilizing successive shifting of the phases between the two segments being correlated to find regions of highest possible correlation. A running account of the maximum cross correlation values for all of the segment pairs of the two signatures are kept.
    Type: Grant
    Filed: December 30, 1977
    Date of Patent: December 5, 1978
    Assignee: International Business Machines Corporation
    Inventors: Noel M. Herbst, Chao N. Liu
  • Patent number: 4128891
    Abstract: A relational data base system utilizing magnetic bubble domain storage. The bubble domain storage is located on a magnetic chip and includes storage circuitry for storing bubble domains in columns and rows. The bubble domains are coded to represent data, and the rows and columns of bubbles correspond to tables of data which are determined by various relations. Current activated transfer gates located on the magnetic chip are used to select a particular row or a particular column of bubble domains for accessing. The magnetic chip also includes a write circuit for writing bubble domains into storage and a read circuit for reading bubble domains removed from storage. Located off the magnetic chip are column addressing circuits, row addressing circuits, interface circuitry, and a computer central processing unit.
    Type: Grant
    Filed: December 30, 1976
    Date of Patent: December 5, 1978
    Assignee: International Business Machines Corporation
    Inventors: Yeong S. Lin, Chao N. Liu, Donald T. Tang
  • Patent number: 3990060
    Abstract: The data stored in a coincident block access bubble domain memory with bit-organized chips is encrypted by skewing or permuting selected word bits by predetermined amounts. This is implemented by providing an additional current loop on some or all of the chips which overlies the major loop pattern and has nodes at the similar vector poles of the major loop. The proper energization of selected ones of these additional current loops, under the control of a security key, inhibits or suppresses the advance of the bubble domains in the corresponding major loops for a predetermined number of cycles of the in-plane propagating field, thus skewing the word bits in these chips with respect to the remaining word bits in the unsuppressed chips. Decryption is accomplished by further inhibiting the same major loops for the necessary number of cycles to restore word bit synchronization throughout the memory.
    Type: Grant
    Filed: March 27, 1974
    Date of Patent: November 2, 1976
    Assignee: International Business Machines Corporation
    Inventors: Yeong S. Lin, Chao N. Liu, Donald T. Tang