Patents by Inventor Joshua S. Zhu

Joshua S. Zhu 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: 6487282
    Abstract: A telephone-based automatic meter reading (AMR) system includes a telemetry device through which a host computer can collect meter readings remotely. So that the telemetry device does not interfere with customer usage of other telephone devices on the telephone line, an apparatus and method is provided which enables the telemetry device to sense both the static off-hook status and the dynamic off-hook status of the telephone line. Numerous circuit components in the telemetry device are shared in sensing both the static and the dynamic off-hook status. Whenever it is determined that a telephone device is, or has become, off-hook, the telemetry device is prevented from using the telephone line. Isolation between the telephone line and the meters is ensured using a transformer and optocouplers.
    Type: Grant
    Filed: July 31, 2000
    Date of Patent: November 26, 2002
    Assignee: FirstPoint Energy Corp.
    Inventors: Yongping Xia, Joshua S. Zhu
  • Patent number: 6347135
    Abstract: A telephone-based automatic meter reading (AMR) system includes a telemetry device through which a host computer can collect meter readings remotely. The telemetry device has one or more ports to read one or more meters at pre-scheduled time intervals. All data read from the meter(s) is stored in a non-volatile memory in the device, and the collected data is transferred back to the host computer according to a predetermined schedule (with a call back interval that can be hourly, daily, weekly or monthly). An apparatus and method is provided which enables the host computer to initiate a special data stream to invoke a powerless circuit portion of the telemetry device—specifically, a telephone-side portion which is electrically isolated from the meter-side circuitry (such as by an optocoupler). The ringing signal on the phone line powers the circuitry in this telephone-side portion of the device such that no AC connection or separate battery power is required.
    Type: Grant
    Filed: May 2, 2000
    Date of Patent: February 12, 2002
    Assignee: Teldata, Inc.
    Inventors: Yongping Xia, Joshua S. Zhu
  • Patent number: 5506715
    Abstract: A lighting system having an electric lamp controlled by an infrared remote controller. The remote controller incorporates a commercially available transmitter and receiver which reliably functions in the presence of infrared noise having frequencies at and about the carrier frequency of the transmitted signal. The remote controller receiver outputs a demodulated signal and a filter acts on the demodulated signal to remove noise present in the demodulated signal caused by the electric lamp by comparing measured time intervals between leading and trailing edges of the demodulated signal to predetermined values defining data elements.
    Type: Grant
    Filed: April 12, 1995
    Date of Patent: April 9, 1996
    Assignee: Philips Electronics North America Corporation
    Inventor: Joshua S. Zhu
  • Patent number: 5107184
    Abstract: A dimming ballast system wherein the light output of the lamp is controlled by a remote source. The ballast output voltage is regulated by a voltage control feedback loop, the dimming function being achieved by varying the set point of the control loop. The remote control signal, coded by interrupting the current flow to the ballast for a short period, is processed digitally by a microcomputer which generates information to vary the control set point. Circuit means are provided to control the filament voltage of the fluorescent lamps such that as the lamps are dimmed down, the filament voltage is maintained or slightly increased, thus prolonging lamp life and stabilizing the lamp light output.
    Type: Grant
    Filed: August 13, 1990
    Date of Patent: April 21, 1992
    Assignee: Electronic Ballast Technology, Inc.
    Inventors: Feng-Kang Hu, Chung M. Lau, Kevin Yang, Joshua S. Zhu, Peter S. Shen, Thomas C. Jednacz
  • Patent number: 5055746
    Abstract: A dimming ballast system wherein the light output of the lamp is controlled by a remote source. The ballast output voltage is regulated by a voltage control feedback loop, the dimming function being achieved by varying the set point of the control loop. The remote control signal, coded by interrupting the current flow to the ballast for a short period, is processed digitally by a microcomputer which generates information to vary the control set point. Circuit means are provided to control the filament voltage of the fluorescent lamps such that as the lamps are dimmed down, the filament voltage is maintained or slightly increased, thus prolonging lamp life and stabilizing the lamp light output.
    Type: Grant
    Filed: August 13, 1990
    Date of Patent: October 8, 1991
    Assignee: Electronic Ballast Technology, Incorporated
    Inventors: Feng-Kang Hu, Chung M. Lau, Kevin Yang, Joshua S. Zhu, Peter S. Shen, Thomas C. Jednacz