Patents by Inventor Robert D. Christie

Robert D. Christie 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).

  • Publication number: 20210128382
    Abstract: A patient support apparatus, such as a hospital bed, includes an alert light assembly or an alert light module having separate zones that are individually illuminated to convey information regarding respective alert conditions. The zones each have indicia related to a particular condition of the patient support apparatus. The illuminated zones are each sufficiently large so as to be seen from afar, such as on the order of ten feet or more. Alternatively or additionally, a GUI of the patient support apparatus displays alert indicia as part of a screen saver. Further alternatively or additionally, the patient support apparatus illuminates an alert light in a manner indicating an optimal time for taking a patient's vital signs.
    Type: Application
    Filed: January 7, 2021
    Publication date: May 6, 2021
    Inventors: Robert M. Zerhusen, Keith R. Kubicek, John D. Christie, Timothy A. Lane, II, Brandon P. Fisk
  • Patent number: 10924052
    Abstract: A system is provided for driving a load such as a multi-phase motor. The system includes a motor driver that has a plurality of switches coupled to a motor to drive a current through each of a plurality of phase coils of the motor. A polarity detection circuit detects a polarity of the current in one or more of the phase coils of the motor to generate a polarity value that represents the detected current polarity. The polarity detection circuit can include at least one comparator that has a first input coupled to a node between two of the plurality of switches, a second input coupled to receive a threshold value, and an output from which the polarity value is provided. Further included is a controller that is configured to provide a plurality of pulse width modulated (PWM) output control signals to the plurality of switches to control the switches to drive the current through the plurality of phase coils of the motor.
    Type: Grant
    Filed: August 8, 2019
    Date of Patent: February 16, 2021
    Assignee: Allegro MicroSystems, LLC
    Inventors: Kamyar Khosravi, Masahira Kurihara, Gianluca Allegrini, Robert D. Christie
  • Publication number: 20210044242
    Abstract: A system is provided for driving a load such as a multi-phase motor. The system includes a motor driver that has a plurality of switches coupled to a motor to drive a current through each of a plurality of phase coils of the motor. A polarity detection circuit detects a polarity of the current in one or more of the phase coils of the motor to generate a polarity value that represents the detected current polarity. The polarity detection circuit can include at least one comparator that has a first input coupled to a node between two of the plurality of switches, a second input coupled to receive a threshold value, and an output from which the polarity value is provided. Further included is a controller that is configured to provide a plurality of pulse width modulated (PWM) output control signals to the plurality of switches to control the switches to drive the current through the plurality of phase coils of the motor.
    Type: Application
    Filed: August 8, 2019
    Publication date: February 11, 2021
    Applicant: Allegro MicroSystems, LLC
    Inventors: Kamyar Khosravi, Masahira Kurihara, Gianluca Allegrini, Robert D. Christie
  • Patent number: 10819257
    Abstract: Systems and methods for computing an average supply current to a motor include a current sensor that is configured to sense a current through the motor. A converter is configured to sample the output of the current sensor at times that are established by a trigger signal and convert the samples into digital current values. A trigger signal generator generates the trigger signal based on one or more pulse width modulated (PWM) motor control signals within a PWM cycle. An average supply current value that indicates the average supply current to the motor is computed by a controller using the digital current values received from the converter.
    Type: Grant
    Filed: September 5, 2019
    Date of Patent: October 27, 2020
    Assignee: Allegro MicroSystems, LLC
    Inventors: Kamyar Khosravi, Masahira Kurihara, Andrew Adib, Robert D. Christie
  • Patent number: 10511223
    Abstract: Methods and apparatus for a voltage regulator having a boost module and a charge pump module. In embodiments, the charge pump module is configured to operate in multiple modes. In embodiments, an IC package includes the boost module and the charge pump with a shared component, such as a capacitor.
    Type: Grant
    Filed: December 6, 2017
    Date of Patent: December 17, 2019
    Assignee: Allegro MicroSystems, LLC
    Inventors: James McIntosh, Robert Stoddard, Robert D. Christie
  • Publication number: 20180166984
    Abstract: Methods and apparatus for a voltage regulator having a boost module and a charge pump module. In embodiments, the charge pump module is configured to operate in multiple modes. In embodiments, an IC package includes the boost module and the charge pump with a shared component, such as a capacitor.
    Type: Application
    Filed: December 6, 2017
    Publication date: June 14, 2018
    Applicant: Allegro MicroSystems, LLC
    Inventors: James McIntosh, Robert Stoddard, Robert D. Christie
  • Patent number: 9935452
    Abstract: A method for signaling between a controller and a driver includes receiving, at a pin of the driver coupled to the controller, a command signal generated by the controller and generating, by the driver at the pin coupled to the controller, a fault signal indicating a fault condition. The driver can be configured to drive a switch and the command signal can be configured to cause the driver to open the switch when the command signal is in a first state and to close the switch when the command signal is in a second state. The command signal being in the first state may correspond to the command signal having a voltage level above a first predetermined threshold and the command signal being in the second state may correspond to the command signal having a voltage level below a second predetermined threshold.
    Type: Grant
    Filed: November 13, 2015
    Date of Patent: April 3, 2018
    Assignee: Allegro MicroSystems, LLC
    Inventors: Christy Looby, Robert D. Christie
  • Patent number: 9735773
    Abstract: Systems and techniques detecting a reverse current are disclosed. An apparatus comprises a switching circuit coupled to a load and a reference node. The switching circuit may be capable of conducting a reverse current from the reference node to the load when a voltage at the load is lower than a voltage at the reference node. A voltage source has a first terminal coupled to the load, a second terminal configured to follow a voltage at the load, and produces a voltage proportional to a voltage drop across the switching circuit. A comparator circuit is coupled to compare a voltage at the second terminal of the voltage source to the voltage at the reference node and configured to indicate when the reverse current has a magnitude greater than a predetermined threshold.
    Type: Grant
    Filed: April 29, 2014
    Date of Patent: August 15, 2017
    Assignee: Allegro Microsystems, LLC
    Inventors: James McIntosh, Robert D. Christie, Douglas Bryce, Walter Morrison Stewart Wilson
  • Publication number: 20170141562
    Abstract: A method for signaling between a controller and a driver includes receiving, at a pin of the driver coupled to the controller, a command signal generated by the controller and generating, by the driver at the pin coupled to the controller, a fault signal indicating a fault condition. The driver can be configured to drive a switch and the command signal can be configured to cause the driver to open the switch when the command signal is in a first state and to close the switch when the command signal is in a second state. The command signal being in the first state may correspond to the command signal having a voltage level above a first predetermined threshold and the command signal being in the second state may correspond to the command signal having a voltage level below a second predetermined threshold.
    Type: Application
    Filed: November 13, 2015
    Publication date: May 18, 2017
    Applicant: ALLEGRO MICROSYSTEMS, LLC
    Inventors: Christy Looby, Robert D. Christie
  • Patent number: 9496708
    Abstract: An isolation circuit is coupled between motor driver half bridge circuits and an electric motor. A motor controller circuit supplies motor drive signals to the motor driver half bridge circuits. The isolation circuit includes transistors coupled in series with the motor windings. Low to medium power diodes are coupled between a reference voltage source and control terminals of the transistors.
    Type: Grant
    Filed: April 3, 2015
    Date of Patent: November 15, 2016
    Assignee: Allegro MicroSystems, LLC
    Inventors: Edward Chappell, Robert D. Christie, James McIntosh, Peter Morris
  • Patent number: 9294084
    Abstract: A transistor drive circuit uses multi-stage slew rate control to drive one or more switching transistors. After a decision is made to change transistor state, a first drive current may be applied to an input terminal of the transistor for a predetermined time duration. After the predetermined time duration, a second drive current may be applied to the input terminal. When the transition between states is substantially complete, the current drive to the input terminal may be changed to a voltage drive. In some embodiments, the predetermined time duration may be based on the start time of a Miller plateau during the transition period.
    Type: Grant
    Filed: November 26, 2014
    Date of Patent: March 22, 2016
    Assignee: Allegro Microsystems, LLC
    Inventors: James McIntosh, Robert D. Christie, Colin Hall, Alistair Wood
  • Publication number: 20150311894
    Abstract: Systems and techniques detecting a reverse current are disclosed. An apparatus comprises a switching circuit coupled to a load and a reference node. The switching circuit may be capable of conducting a reverse current from the reference node to the load when a voltage at the load is lower than a voltage at the reference node. A voltage source has a first terminal coupled to the load, a second terminal configured to follow a voltage at the load, and produces a voltage proportional to a voltage drop across the switching circuit. A comparator circuit is coupled to compare a voltage at the second terminal of the voltage source to the voltage at the reference node and configured to indicate when the reverse current has a magnitude greater than a predetermined threshold.
    Type: Application
    Filed: April 29, 2014
    Publication date: October 29, 2015
    Applicant: Allegro Microsystems, LLC
    Inventors: James McIntosh, Robert D. Christie, Douglas Bryce, Walter Morrison Stewart Wilson
  • Publication number: 20150288304
    Abstract: An isolation circuit is coupled between motor driver half bridge circuits and an electric motor. A motor controller circuit supplies motor drive signals to the motor driver half bridge circuits. The isolation circuit includes transistors coupled in series with the motor windings. Low to medium power diodes are coupled between a reference voltage source and control terminals of the transistors.
    Type: Application
    Filed: April 3, 2015
    Publication date: October 8, 2015
    Applicant: ALLEGRO MICROSYSTEMS, LLC
    Inventors: Edward Chappell, Robert D. Christie, James McIntosh, Peter Morris
  • Patent number: 7649325
    Abstract: A circuit includes a capacitive element for coupling across a load element to be energized by a DC signal, a first sense element to monitor an instantaneous sum of currents through the load element and the capacitive element, a switching element to control current through the first sense element, a second sense element coupled to the switching element to sense current through the switching element, an energy storage element coupled to the switching element, a unidirectional current flow element allowing current flow to the load element, and a converter circuit to control the switching element, wherein the converter circuit regulates to the current level monitored across the first sense element, and wherein a converter regulation loop includes a dominant pole to average the current sensed through the first sense element.
    Type: Grant
    Filed: April 3, 2006
    Date of Patent: January 19, 2010
    Assignee: Allegro Microsystems, Inc.
    Inventors: James A. McIntosh, Aldo Togneri, Robert D. Christie