Patents by Inventor Lars Risbo

Lars Risbo 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: 20230362547
    Abstract: --A motor for an electrodynamic loudspeaker and an electrodynamic loudspeaker including the motor. The motor includes a magnetic circuit assembly arranged about a motor axis. The motor includes: a magnetically permeable top plate, a magnetically permeable bottom plate, a magnetically permeable member disposed between, and magnetically coupled to, the magnetically permeable top and bottom plates, a center pole piece and an air gap for receipt of a voice coil. The motor also includes an outwardly projecting magnetically permeable member, or hat, arranged above a top of the air gap. The center pole piece includes a permanent magnet, such as a Neodymium magnet or a Ferrite magnet, extending axially from at least the bottom of the air gap to a magnetically permeable bottom member or to the magnetically permeable bottom plate.
    Type: Application
    Filed: September 1, 2021
    Publication date: November 9, 2023
    Inventors: Lars Risbo, Carsten Tinggaard, Morten Halvosen, Bruno Putzeys
  • Patent number: 11405007
    Abstract: An amplifier, such as a Class D amplifier, having one or more feedback loops comprising a path from the input to the primary amplifier input, where the paths comprise a low pass filter and a compensator which is disabled when the primary amplifier clips.
    Type: Grant
    Filed: July 20, 2018
    Date of Patent: August 2, 2022
    Assignee: PURIFI APS
    Inventors: Bruno Putzeys, Lars Risbo
  • Publication number: 20220167089
    Abstract: A loudspeaker with a non-uniform surround, a membrane and a stiffening element preventing the surround from flexing the membrane during operation. A non-uniform surround does not have the same cross section, along the radius of the speaker if circular, all around the perimeter of the membrane as some portions will be upwardly directed and other portions downwardly directed.
    Type: Application
    Filed: April 8, 2020
    Publication date: May 26, 2022
    Inventors: Bruno PUTZEYS, Lars RISBO, Carsten TINGGAARD
  • Publication number: 20220141592
    Abstract: A motor for an electrodynamic loudspeaker. The motor includes a magnetic circuit assembly arranged about a motor axis. The assembly includes: an outer magnet, a magnetically permeable top plate, a magnetically permeable bottom plate, a center pole piece and an air gap for receipt of a voice coil. The air gap is formed by an inner wall of the magnetically permeable top plate facing an axially extending peripheral wall section of the center pole piece to define the air gap. The magnetic circuit assembly also includes an outwardly projecting magnetically permeable member arranged above the air gap. The center pole piece has a magnetic member extending axially from the bottom of the air gap to a magnetically permeable bottom member or to the bottom plate. The magnetic member exhibits a relative AC magnetic permeability smaller than 10, which corresponds to the relative AC magnetic permeability of free air.
    Type: Application
    Filed: February 12, 2020
    Publication date: May 5, 2022
    Inventors: Lars Risbo, Carsten Tinggaard, Morten Halvorsen, Bruno Putzeys
  • Patent number: 11290823
    Abstract: The present invention discloses a loudspeaker driver comprising a magnet system having at least one gap where in each gap a voice coil assembly is arranged for movement in the gap, wherein either two distinct coils are arranged on the voice coil assembly, one above the other, and the magnet system comprises two pole pieces, one above the other, creating a pair of magnetized areas between said pole pieces and a yoke, such that a magnetic flux field is created between each pole piece and the yoke.
    Type: Grant
    Filed: April 11, 2019
    Date of Patent: March 29, 2022
    Assignee: DALI A/S
    Inventors: Kim Kristiansen, Lars Risbo, Bruno Putzeys
  • Patent number: 11258411
    Abstract: A Class D amplifier having an integrating primary amplifier with an internal feedback, the amplifier further comprising a feedback loop with a filter of at least second order.
    Type: Grant
    Filed: July 20, 2018
    Date of Patent: February 22, 2022
    Assignee: PURIFI APS
    Inventors: Bruno Putzeys, Lars Risbo
  • Patent number: 11082017
    Abstract: An amplifier comprising a gain stage with a feedback network comprising two ports between which at least three capacitors are connected in series and between each pair of capacitors a resistor is connected to a predetermined voltage. The gain stage is provided in a feedback loop over a primary amplifier.
    Type: Grant
    Filed: July 20, 2018
    Date of Patent: August 3, 2021
    Assignee: PURIFI APS
    Inventors: Bruno Putzeys, Lars Risbo
  • Publication number: 20210029463
    Abstract: The present invention discloses a loudspeaker driver comprising a magnet system having at least one gap where in each gap a voice coil assembly is arranged for movement in the gap, wherein either two distinct coils are arranged on the voice coil assembly, one above the other, and the magnet system comprises two pole pieces, one above the other, creating a pair of magnetized areas between said pole pieces and a yoke, such that a magnetic flux field is created between each pole piece and the yoke.
    Type: Application
    Filed: April 11, 2019
    Publication date: January 28, 2021
    Inventors: Kim Kristiansen, Lars Risbo, Bruno Putzeys
  • Publication number: 20200389135
    Abstract: An amplifier, such as a Class D amplifier, having one or more feedback loops comprising a path from the input to the primary amplifier input, where the paths comprise a low pass filter and a compensator which is disabled when the primary amplifier clips.
    Type: Application
    Filed: July 20, 2018
    Publication date: December 10, 2020
    Inventors: Bruno PUTZEYS, Lars RISBO
  • Publication number: 20200382084
    Abstract: A Class D amplifier having an integrating primary amplifier with an internal feedback, the amplifier further comprising a feedback loop with a filter of at least second order.
    Type: Application
    Filed: July 20, 2018
    Publication date: December 3, 2020
    Inventors: Bruno PUTZEYS, Lars RISBO
  • Publication number: 20200313633
    Abstract: An amplifier comprising a gain stage with a feedback network comprising two ports between which at least three capacitors are connected in series and between each pair of capacitors a resistor is connected to a predetermined voltage. The gain stage is provided in a feedback loop over a primary amplifier.
    Type: Application
    Filed: July 20, 2018
    Publication date: October 1, 2020
    Inventors: Bruno PUTZEYS, Lars RISBO
  • Patent number: 10728659
    Abstract: The present invention relates in one aspect to a method of controlling or limiting diaphragm excursion of a loudspeaker. The method comprising steps of receiving a first audio signal and deriving an excursion signal representing diaphragm excursion of the electrodynamic loudspeaker from the first audio signal. The method additionally comprises deriving an excursion envelope from the excursion signal and applying a second audio signal, derived from the first audio signal, to an input of an adjustable low-frequency suppressor. The second audio signal is filtered by the adjustable low-frequency suppressor to selectively attenuate low-frequency components based on the excursion envelope to produce a processed audio signal with reduced low-frequency content.
    Type: Grant
    Filed: May 2, 2017
    Date of Patent: July 28, 2020
    Assignee: Purifi APS
    Inventors: Bruno Putzeys, Lars Risbo
  • Patent number: 10397701
    Abstract: A system includes a class D amplifier and a current steering digital-to-analog converter (DAC) directly connected to the class D amplifier. The system also includes a common mode servo circuit coupled to a node interconnecting the current steering DAC to the class D amplifier. The common servo circuit amplifies a difference between a common mode signal determined from the node and a reference voltage and generates a feedback current to the node based on the amplified difference. A feed-forward common-mode compensation circuit is included to reduce an alternating current (AC) ripple from the class D amplifier. The feed-forward common-mode compensation circuit includes first and second resistors coupled to respective outputs of the class D amplifier. A current mirror is coupled to the first and second resistors and is configured to sink a current from the node to ground that approximates a common mode feedback current of the class D amplifier.
    Type: Grant
    Filed: October 31, 2018
    Date of Patent: August 27, 2019
    Assignee: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Lars Risbo, Ryan Erik Lind, Jasjot Singh Chadha
  • Patent number: 10313787
    Abstract: A predictive back-emf protection methodology for an electromechanical system, including a signal processor that processes a source signal to provide a modified source signal, a driver that converts the modified source signal to a drive signal, and an electromechanical transducer that generates, from the drive signal, a transducer response, and a back-emf signal coupled back to the driver output. A predictive back-emf generator (such as a routine in the signal processor) is characterized by a back-emf transfer function (linear parameterized model of the electromechanical transducer) for transforming an input signal into a transform back-emf representation of a back-emf signal predicted by the back-emf transfer function as a response of the electromechanical transducer to such input signal. The signal processor processes the source signal based on the transform back-emf representation to generate the modified source signal input to the driver.
    Type: Grant
    Filed: August 14, 2015
    Date of Patent: June 4, 2019
    Assignee: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Lars Risbo, Anker Bjørn-Josefsen, Kim N. Madsen
  • Publication number: 20190149920
    Abstract: The present invention relates in one aspect to a method of controlling or limiting diaphragm excursion of a loudspeaker. The method comprising steps of receiving a first audio signal and deriving an excursion signal representing diaphragm excursion of the electrodynamic loudspeaker from the first audio signal. The method additionally comprises deriving an excursion envelope from the excursion signal and applying a second audio signal, derived from the first audio signal, to an input of an adjustable low-frequency suppressor. The second audio signal is filtered by the adjustable low-frequency suppressor to selectively attenuate low-frequency components based on the excursion envelope to produce a processed audio signal with reduced low-frequency content.
    Type: Application
    Filed: May 2, 2017
    Publication date: May 16, 2019
    Applicant: Purifi APS
    Inventors: Bruno PUTZEYS, Lars RISBO
  • Publication number: 20190069087
    Abstract: A system includes a class D amplifier and a current steering digital-to-analog converter (DAC) directly connected to the class D amplifier. The system also includes a common mode servo circuit coupled to a node interconnecting the current steering DAC to the class D amplifier. The common servo circuit amplifies a difference between a common mode signal determined from the node and a reference voltage and generates a feedback current to the node based on the amplified difference. A feed-forward common-mode compensation circuit is included to reduce an alternating current (AC) ripple from the class D amplifier. The feed-forward common-mode compensation circuit includes first and second resistors coupled to respective outputs of the class D amplifier. A current mirror is coupled to the first and second resistors and is configured to sink a current from the node to ground that approximates a common mode feedback current of the class D amplifier.
    Type: Application
    Filed: October 31, 2018
    Publication date: February 28, 2019
    Inventors: Lars Risbo, Ryan Erik Lind, Jasjot Singh Chadha
  • Patent number: 10158942
    Abstract: A system includes a class D amplifier and a current steering digital-to-analog converter (DAC) directly connected to the class D amplifier. The system also includes a common mode servo circuit coupled to a node interconnecting the current steering DAC to the class D amplifier. The common servo circuit amplifies a difference between a common mode signal determined from the node and a reference voltage and generates a feedback current to the node based on the amplified difference. A feed-forward common-mode compensation circuit is included to reduce an alternating current (AC) ripple from the class D amplifier. The feed-forward common-mode compensation circuit includes first and second resistors coupled to respective outputs of the class D amplifier. A current mirror is coupled to the first and second resistors and is configured to sink a current from the node to ground that approximates a common mode feedback current of the class D amplifier.
    Type: Grant
    Filed: February 15, 2018
    Date of Patent: December 18, 2018
    Assignee: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Lars Risbo, Ryan Erik Lind, Jasjot Singh Chadha
  • Publication number: 20180176683
    Abstract: A system includes a class D amplifier and a current steering digital-to-analog converter (DAC) directly connected to the class D amplifier. The system also includes a common mode servo circuit coupled to a node interconnecting the current steering DAC to the class D amplifier. The common servo circuit amplifies a difference between a common mode signal determined from the node and a reference voltage and generates a feedback current to the node based on the amplified difference. A feed-forward common-mode compensation circuit is included to reduce an alternating current (AC) ripple from the class D amplifier. The feed-forward common-mode compensation circuit includes first and second resistors coupled to respective outputs of the class D amplifier. A current mirror is coupled to the first and second resistors and is configured to sink a current from the node to ground that approximates a common mode feedback current of the class D amplifier.
    Type: Application
    Filed: February 15, 2018
    Publication date: June 21, 2018
    Inventors: Lars Risbo, Ryan Erik Lind, Jasjot Singh Chadha
  • Patent number: 9967663
    Abstract: Systems and methods for loudspeaker protection against excessive excursion are described. In an illustrative, non limiting embodiment, a method may include splitting an input signal into two or more signals, each of the two or more signals within a given frequency band; independently selecting between a power attenuation or an excursion attenuation for each of the two or more signals; independently applying the selected power attenuation or excursion attenuation to each of the two or more signals; combining the attenuated two or more signals into an output signal; and providing the output signal to a loudspeaker.
    Type: Grant
    Filed: December 2, 2015
    Date of Patent: May 8, 2018
    Assignee: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Anker Bjoern-Josefsen, Lars Risbo, Theis Christiansen
  • Patent number: D916053
    Type: Grant
    Filed: February 26, 2019
    Date of Patent: April 13, 2021
    Inventor: Lars Risbo