Patents by Inventor Siu Hong Choy

Siu Hong Choy 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: 7494601
    Abstract: The present invention provides a piezoelectric ceramic composition, especially a lead-free piezoelectric ceramic composition, with a suitable amount of CeO2 or CeO2-containing complex additives, which is represented by the following formula: (Na0.475K0.475Li0.05)(Nb1-xAx)O3+yCeO2+zBO2 wherein “A” represents Sb or Sb+Ta, “B” represents a tetravalent transition metal, 0?x?0.2, 0.2 wt %<y<1.2 wt % and 0?z 1 wt %. Addition of CeO2 or CeO2-containing complex additives suppresses melting and abnormal grain growth of (Na0.475K0.475Li0.05)(Nb1-xAx)O3 during sintering, thereby improving sinterability and increasing the density of the composition. As a result, the dielectric and piezoelectric properties of the ceramics are enhanced. Furthermore, the represented compositions have a wide sintering temperature range so that the process for preparing such a lead-free piezoelectric ceramic composition has high degree efficiency.
    Type: Grant
    Filed: February 28, 2006
    Date of Patent: February 24, 2009
    Assignee: The Hong Kong Polytechnic University
    Inventors: Xiaoxing Wang, Kin Wing Kwok, Helen Lai Wah Chan, Siu Hong Choy
  • Patent number: 7240711
    Abstract: The invention provides an apparatus and method for aligning a bonding tool. A force sensor having a plurality of force sensing sections is configured to measure a force generated by the bonding tool on the force sensor. Each sensing section is adapted to individually detect an amount of force from a part of the bonding tool acting on that sensing section, so that an alignment of the bonding tool may be determined.
    Type: Grant
    Filed: January 21, 2004
    Date of Patent: July 10, 2007
    Assignee: ASM Assembly Automation Ltd.
    Inventors: Lai Wa Helen Chan, Siu Hong Choy, Chou Kee Peter Liu, Ming Wai Kelvin Ng, Yuk Cheung Au