Patents by Inventor Mao-chi Chang

Mao-chi Chang 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: 5570207
    Abstract: A holographic image identification system includes an image reconstruction device having a laser beam source movable along an arc path to selectively project a laser beam onto a hologram located on the center of the arc path at a preselected incidental angle so as to form an image on a screen to be received by a charge coupling device which converts the image into an electrical signal and transmits the electrical signal to a computer to compare with a reference image stored in the storage memory of the computer. The incidental angle of the laser beam is also fed to the computer to compare with a pre-stored value associated with the reference image for double-check of the correctness of the holographic image.
    Type: Grant
    Filed: June 28, 1994
    Date of Patent: October 29, 1996
    Inventor: Mao-chi Chang