Patents by Inventor Yian Leng Chang

Yian Leng 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: 6396942
    Abstract: A ball grid array inspection and location method and apparatus includes a raw feature finding processor which uses a feature finding algorithm to find ball features (irrespective of number) and generate a list of raw features as an X and Y location for each feature located. An angle estimation processor receives the list of raw features, a user estimated orientation angle, and ball-to-ball pitch information and determines an estimated grid angle. An on-grid check processor receives the estimated grid angle, the list of raw features and the ball-to-ball pitch information and produces a set or list of on-grid features in the form of a list X and Y translation parameters for each feature/ball found on-grid.
    Type: Grant
    Filed: May 10, 2000
    Date of Patent: May 28, 2002
    Assignee: Cognex Corporation
    Inventors: Yian Leng Chang, Nigel John Foster, Jane Alice Loizeaux
  • Patent number: 6324299
    Abstract: The invention provides a method of locating an object within a client region, where the object has a plurality of portions. The method includes defining a full geometric model of the object; defining a plurality of geometric sub-models of the object; determining coarse candidate poses of the object within the region using an image of the region and the full geometric model of the object; determining the fine pose of each of a plurality of portions of the object using the coarse candidate poses of the object within the region, and at least some of said geometric sub-models, to provide a plurality of object portion fine poses within the region; and then determining the fine poses of the object within the region using said plurality of object portion fine poses of a plurality of portions of the object includes determining the coarse poses of each of a plurality of portions of the object, and using each coarse pose, determining the fine pose of each of the plurality of portions of the object.
    Type: Grant
    Filed: April 3, 1998
    Date of Patent: November 27, 2001
    Assignee: Cognex Corporation
    Inventors: Karen B. Sarachik, Ivan A. Bachelder, Cyril C. Marrion, Yian Leng Chang
  • Patent number: 6252986
    Abstract: A method is provided for finding an image of an object having a concentric profile, wherein the concentric profile has an inner profile and an outer profile, and wherein the inner profile is in concentric relationship with the outer profile. In another general aspect of the invention, a method is provided for finding an image of an object having a concentric profile, the concentric profile having a plurality of constituent profiles, where each profiles of the plurality of constituent profiles scales independently in a fine search phase. The methods of the invention can find circular profiles of a nozzle that scale non-uniformly as well as that scale uniformly, and therefore can be used to find one or more rings or profiles of the image of a nozzle. Further, the methods of the invention can provide superior accuracy regarding the position of the nozzle for many applications.
    Type: Grant
    Filed: December 18, 1998
    Date of Patent: June 26, 2001
    Assignee: Cognex Corporation
    Inventor: Yian Leng Chang
  • Patent number: 6151406
    Abstract: A ball grid array inspection and location method and apparatus includes a raw feature finding processor which uses a feature finding algorithm to find ball features (irrespective of number) and generate a list of raw features as an X and Y location for each feature located. An angle estimation processor receives the list of raw features, a user estimated orientation angle, and ball-to-ball pitch information and determines an estimated grid angle. An on-grid check processor receives the estimated grid angle, the list of raw features and the ball-to-ball pitch information and produces a set or list of on-grid features in the form of a list X and Y translation parameters for each feature/ball found on-grid.
    Type: Grant
    Filed: October 9, 1997
    Date of Patent: November 21, 2000
    Assignee: Cognex Corporation
    Inventors: Yian Leng Chang, Nigel John Foster, Jane Alice Loizeaux