Patents by Inventor Lihu M. Chiu

Lihu M. Chiu 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: 7513431
    Abstract: A method and system for enhancing the accuracy of RFID tag reading is disclosed. An imaging device is used to facilitate aiming of the RFID tag in a manner that mitigates the likelihood of inadvertently reading a nearby RFID tag instead of the desired tag. In this manner, the utility of the RFID reader is substantially enhanced.
    Type: Grant
    Filed: March 4, 2005
    Date of Patent: April 7, 2009
    Assignee: Printronix, Inc.
    Inventor: Lihu M. Chiu
  • Patent number: 7479883
    Abstract: An RFID verifier is configured to vary a slope for a ramp-modulated interrogating signal to determine the slope at which an interrogated RFID tag no longer responds to the interrogating signal. In this fashion, the RFID verifier may obtain a measure of quality for the interrogated RFID tag with respect to the tag's ability to decode ramp-modulated signals.
    Type: Grant
    Filed: August 1, 2006
    Date of Patent: January 20, 2009
    Assignee: Printronix, Inc.
    Inventor: Lihu M. Chiu
  • Publication number: 20080257962
    Abstract: In one embodiment, barcode widths and barcode space widths are estimated using a first light source separated by a known distance from a second light source. The estimations are determined by scanning the first and second light sources over a barcode while detecting a corresponding first reflected light beam and a second reflected light beam from the scanned barcode; processing the first reflected light beam to determine first barcode edge detections; processing the second reflected light beam to determine second barcode edge detections; estimating a first acceleration for the scanning; estimating a second acceleration for the scanning, wherein the second acceleration is substantially orthogonal to the first acceleration; deriving an overall velocity for the scanning by integrating the first and second accelerations; and comparing the first edge detections to the second edge detections using the overall velocity to derive the barcode widths and spaces.
    Type: Application
    Filed: April 23, 2007
    Publication date: October 23, 2008
    Inventor: Lihu M. Chiu
  • Patent number: 7400989
    Abstract: An RFID verifier includes a transmit signal strength indicator (TSSI) and a receive signal strength indicator (RSSI). Using the TSSI, the RFID verifier may determine the amount of power an interrogated RFID tag is illuminated with. Similarly, using the RSSI, the RFID verifier may determine the amount of power returned to the RFID verifier by the RFID tag. By processing the returned power and the illuminating power with a transfer function, the RFID verifier may provide an absolute indicia of quality for the interrogated RFID tag.
    Type: Grant
    Filed: September 27, 2004
    Date of Patent: July 15, 2008
    Assignee: Printronix, Inc.
    Inventors: Theodore A. Chapman, Lihu M. Chiu
  • Patent number: 7389931
    Abstract: In one embodiment, a system is provided that includes: a laser source is provided that producing a laser beam that diverges in a first direction and in a second direction orthogonal to the first direction; a lens positioned to receive the laser beam from the laser source and provide a magnified laser beam; and an opaque screen having an elongated aperture having a longitudinal axis aligned substantially parallel to the first direction, the aperture being positioned to intercept the magnified laser beam such that a projected laser beam from the aperture is focused into an elongated illumination spot, the elongated illumination spot having a longitudinal axis aligned substantially parallel to the second direction.
    Type: Grant
    Filed: May 17, 2006
    Date of Patent: June 24, 2008
    Assignee: Printronix, Inc.
    Inventor: Lihu M. Chiu
  • Patent number: 7348885
    Abstract: In one embodiment, a capacitive encoding system is provided that includes a pair of capacitive elements formed from an arrangement of stripline conductors.
    Type: Grant
    Filed: August 19, 2005
    Date of Patent: March 25, 2008
    Assignee: Printronix, Inc.
    Inventor: Lihu M. Chiu
  • Patent number: 7342499
    Abstract: In one embodiment, a multi-band near-field antenna for an RFID encoder includes a substrate; an internal coil antenna defined within the substrate; an annular ground plane defined on a first surface of the substrate; a second ground plane defined on an opposing second surface of the substrate, wherein the annular ground plane and the second ground plane form a Faraday cage for the internal coil antenna; and a second antenna disposed on the opposing second surface within the annulus defined by the annular ground plane.
    Type: Grant
    Filed: January 26, 2006
    Date of Patent: March 11, 2008
    Assignee: Printronix, Inc.
    Inventors: Lihu M. Chiu, Hai Cao, John Kinley
  • Publication number: 20070268142
    Abstract: In one embodiment, a near-field RFID encoder is provided that includes a pair of capacitive elements formed from an arrangement of stripline conductors. The near-field encoder may non-resonantly excite RFID tags. In addition, the near-field encoder may characterize RFID tag quality using a VSWR measurement.
    Type: Application
    Filed: May 17, 2006
    Publication date: November 22, 2007
    Inventors: Lihu M. Chiu, Richard E. Schumaker, Theodore A. Chapman
  • Publication number: 20070267499
    Abstract: In one embodiment, a system is provided that includes: a laser source is provided that producing a laser beam that diverges in a first direction and in a second direction orthogonal to the first direction; a lens positioned to receive the laser beam from the laser source and provide a magnified laser beam; and an opaque screen having an elongated aperture having a longitudinal axis aligned substantially parallel to the first direction, the aperture being positioned to intercept the magnified laser beam such that a projected laser beam from the aperture is focused into an elongated illumination spot, the elongated illumination spot having a longitudinal axis aligned substantially parallel to the second direction.
    Type: Application
    Filed: May 17, 2006
    Publication date: November 22, 2007
    Inventor: Lihu M. Chiu
  • Patent number: 7268686
    Abstract: In one embodiment, a system for communicating with an RFID tag is provided that includes: a capacitive encoder adapted for placement in proximity of the RFID tag and operable to transmit a first operating signal to the RFID tag for communicating with the RFID tag; wherein the capacitive encoder is further operable to transmit to the RFID tag a second operating signal adapted to excite the RFID tag such that RF radiations from the RFID tag to adjacent RFID tags are nullified.
    Type: Grant
    Filed: March 4, 2005
    Date of Patent: September 11, 2007
    Assignee: Printronix, Inc.
    Inventor: Lihu M. Chiu
  • Patent number: 7239243
    Abstract: In one embodiment, a system for obtaining an image of an RFID tag comprising a transponder and a tag antenna is provided, the system comprising: a plurality of inductors, each inductor being associated with a capacitor to form a resonant tank circuit, wherein each resonant tank circuit has a first resonant frequency in the presence of metal and a second resonant frequency in the absence of metal; a signal processor configured to determine a resonant frequency for each resonant tank circuit in the presence of the tag antenna; and a processor configured to compare the resonant frequency of each resonant tank circuit to the first and second resonant frequency to determine an image of the tag antenna.
    Type: Grant
    Filed: March 4, 2005
    Date of Patent: July 3, 2007
    Assignee: Printronix, Inc.
    Inventor: Lihu M. Chiu
  • Patent number: 7221278
    Abstract: An RFID verifier includes a transmit signal strength indicator (TSSI) and a receive signal strength indicator (RSSI). Using the TSSI, the RFID verifier may determine the amount of power an interrogated RFID tag is illuminated with. Similarly, using the RSSI, the RFID verifier may determine the amount of power returned to the RFID verifier by the RFID tag. By comparing the returned power to the amount used to illuminate the interrogated tag, the RFID verifier may provide an indicia of quality for the interrogated RFID tag.
    Type: Grant
    Filed: September 16, 2004
    Date of Patent: May 22, 2007
    Assignee: Printronix, Inc.
    Inventors: Lihu M. Chiu, Theodore A. Chapman