Patents by Inventor Hai C. Chen

Hai C. Chen 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: 5004076
    Abstract: A controlling apparatus is provided to control an electric elevator in a more efficient manner.
    Type: Grant
    Filed: April 18, 1989
    Date of Patent: April 2, 1991
    Inventors: Hai C. Chen, Felix W. H. Yeh
  • Patent number: 4970504
    Abstract: A security system for controlling access to property having a user-operated keyboard to key in and reset a composite password code. An indicator visually displays at least one code symbol varying with time. A memory device stores a current composite password code including at least two code symbols so that upon entry of the keyed-in password code through the keyboard, one of the stored password code symbols is replaced directly by the time varying code symbol to form a regenerated, composite password code which is then compared with the keyed-in password code to grant access to the property when coincidence occurs between the keyed-in and the regenerated password codes. In response to non-coincidence, an alerting signal is generated to indicate the incorrect password condition.
    Type: Grant
    Filed: December 19, 1988
    Date of Patent: November 13, 1990
    Inventor: Hai C. Chen
  • Patent number: 4812841
    Abstract: A computer-controlled password lock system having a user operated keyboard to key in and reset a password. An indicator visually displays at least one code symbol varying with time. A memory device stores a current password including at least two code symbols so that upon entry of a keyed-in password code through the keyboard, one of the stored password code symbols of the current password is replaced by the time varying code symbol and password then compared with the keyed-in password code to generate a lock opening signal when coincidence occurs. In response to non-coincidence, an alerting signal is generated to indicate the incorrect password condition.
    Type: Grant
    Filed: May 26, 1987
    Date of Patent: March 14, 1989
    Inventor: Hai C. Chen