Patents by Inventor Ralph M. Mitchell

Ralph M. Mitchell 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: 5554921
    Abstract: An improved battery charger apparatus and method with multiple range current control includes a programmable current source (101) for providing a charge current (105) to charge a battery (107). An amplitude of the charge current (105) is dependent on a charge demand signal (117) supplied to the programmable current source (101). A scaler (109) provides a scaled charge current signal (111), dependent on the charge current (105) and a current range signal (113). A charge current control unit (115) regulates the charge current (105) by providing the charge demand signal (117) to the programmable current source (101) dependent on the scaled charge current signal (111). More than one amplitude of the charge current (105) is provided to the battery (107), dependent on more than one current range signal (113) provided by the charge current control unit (115) to the scaler (109).
    Type: Grant
    Filed: December 23, 1993
    Date of Patent: September 10, 1996
    Assignee: Motorola, Inc.
    Inventors: Edward Li, Ralph M. Mitchell, John H. Aseltine
  • Patent number: 5500579
    Abstract: An electric motor control with integral battery charger includes battery terminals (201) for connection to a battery (203). A boost converter circuit (111) is coupled to an armature winding (209) of the electric motor (117), and has an input (131) coupled to a power source (211). A buck converter circuit (105) is coupled to a field winding (207) of the electric motor (117), and an input (133) coupled to the power source (211). A controller (205), is coupled to the battery terminals (201) and the power source (211). The controller (205) couples a boost output (107) of the boost converter circuit (111 ) to the battery terminals (201) while a terminal voltage of the power source (211) is lower than a terminal voltage of the battery (203) measured at the battery terminals (201), and couples a buck output (107) of the buck converter circuit (105) to the battery terminals (201 ) while the terminal voltage of the power source (211) is higher than the terminal voltage of the battery (203).
    Type: Grant
    Filed: January 3, 1995
    Date of Patent: March 19, 1996
    Assignee: Motorola, Inc.
    Inventors: Sang H. Kim, Edward Li, Ralph M. Mitchell
  • Patent number: 4780656
    Abstract: An electronic control for a motor drives the motor with pulses of current, and protects the motor from extreme values of line voltage and motor current. A current sensor, connected in series with a conductor which supplies current to the motor windings, develops a monitoring signal that is sensed for the purpose of shutting down the motor when the monitoring signal indicates that the motor current is excessive. A power supply in the control isolates the control from the AC line voltage, provides regulated DC voltages to power various portions of the control, and provides an unregulated DC sense voltage which indicates when the AC line voltage is too high or too low so that the motor can be shut down.
    Type: Grant
    Filed: September 8, 1987
    Date of Patent: October 25, 1988
    Assignee: Motorola, Inc.
    Inventor: Ralph M. Mitchell
  • Patent number: 4713347
    Abstract: Methods, apparatus and sensors are described for detection of specific ligands in a fluid sample by measuring ligand-specific changes in the bulk electrical conductance (or resistance) of a fixed test volume, with antiligand or ligand localized in or near that volume.
    Type: Grant
    Filed: January 14, 1985
    Date of Patent: December 15, 1987
    Assignee: Sensor Diagnostics, Inc.
    Inventors: David H. Mitchell, Ralph M. Mitchell