A method for driving a voice coil of a loudspeaker may include providing a magnetic circuit having an air gap, providing a voice coil suspended in the air gap, and applying an audio signal to the voice coil to move it along a travelling axis. The voice coil comprises a main voice coil section, and a pair of auxiliary voice coil sections arranged along the travelling axis with auxiliary voice coil sections arranged respectively on either side of the main voice coil section. Applying an audio signal comprises continuously coupling a main driving signal based on the audio signal to the main voice coil and selectively coupling an auxiliary driving signal based on the audio signal to the pair of auxiliary voice coil sections. The disclosed embodiments further relate to a voice coil driving system and a loudspeaker comprising a voice coil driving system.

A method for evaluating ultimate demagnetization temperature of magnet includes displaying a workspace interface. The workspace interface at least includes an operation area, a model view displaying area, and a demagnetization curve displaying area. A geometric model view of a geometric model file to be solved is displayed in the model view displaying area. Information input is received through the operation area and the model view displaying area, and performance parameters and designing variables to be solved and formulas are imported accordingly. Through calculating, a demagnetization curve with post-treatment for the magnet is obtained and displayed in the demagnetization curve displaying area.

Methods, systems, circuits and computer program products provide an output signal to drive an electromechanical transducer that selectively contains a cooling component when a thermal limit of a voice coil of the electromechanical transducer is exceeded and which air-cools the transducer by convection. An indication of a temperature of a voice coil of the electromechanical transducer is determined and compared with a thermal limit of the transducer. If the thermal limit of the transducer is exceeded by the indication of the temperature of the voice coil, the cooling component is introduced to the output signal that drives the transducer. The cooling component is a signal having a frequency within a low-frequency resonance portion of the response of the electromechanical transducer, so that additional air convection is caused at the transducer to remove heat from the voice coil due to the cooling component of the output signal.

A broadband speaker includes: a first vibration plate configured to operate in a high frequency band, a second vibration plate disposed coaxially outside the first vibration plate, a first voice coil connected to the first vibration plate to vibrate the first vibration plate, a second voice coil disposed coaxially outside the first voice coil and connected to the second vibration plate, a magnet assembly configured to form a magnetic field, an amplifier configured to apply a first output signal of a high frequency band to the first voice coil and a second output signal of a frequency band lower than that of the first output signal to the second voice coil, and a controller configured to control the amplifier to apply a signal for suppressing vibration of the second vibration plate to the second voice coil when the first output signal is applied to the first voice coil.

Techniques, methods, systems, and other mechanisms for measuring the excursion of a speaker while being actively driven. Measuring excursion can involve attaching a flexible printed coil (FPC), including a sense coil, to the speaker, and monitoring an induced current as produced though the sense coil, and further detecting that violation of an excursion limit for the speaker may likely occur.

The present disclosure relates to a method for simultaneously operating a loudspeaker assembly in a loudspeaker function and in a microphone function. The loudspeaker assembly comprises a coil, which is movably mounted in the magnetic field of a magnet, and a diaphragm, which is mechanically coupled to the coil, wherein the magnet produces a magnetic flux density (B), the coil, has an effective length in the magnetic field, and the diaphragm has an area (A). In order to determine a first transfer function Z.sub.M, a first calibration state is set, in which an external sound pressure (p) on the diaphragm is equal to zero. In order to determine a second transfer function Z.sub.C, a second calibration state is set, in which movement of the diaphragm is suppressed. Subsequently, in normal operation the current (I) flowing through the coil and the voltage (U) dropping across the coil are measured and the external sound pressure (p) on the diaphragm is determined using the magnetic flux density (B), the effective length of the coil in the magnetic field of the magnet, the first transfer function, the second transfer function, the area (A) of the diaphragm, the current (I) measured by the measuring device in normal operation, and the voltage (U) measured by the measuring device in normal operation. The present disclosure further relates to a corresponding loudspeaker assembly.

A bone conduction speaker is provided herein. The bone conduction speaker may include a magnetic circuit component for providing a magnetic field, a vibration component located in the magnetic field, and a case. At least a part of the vibration component may convert an electrical signal into a mechanical vibration signal. The case may include a case panel facing a human body side and a case back opposite to the case panel, and accommodate the vibration component that causes the case panel and the case back to vibrate. A vibration of the case panel may have a first phase, and a vibration of the case back may have a second phase. When frequencies of the vibration of the case panel and the case back are within 2000 Hz to 3000 Hz, an absolute value of a difference between the first and the second phase(s) may be less than 60 degrees.

The present disclosure relates to a method for simultaneously operating a loudspeaker assembly in a loudspeaker function and in a microphone function. The loudspeaker assembly comprises a coil, which is movably mounted in the magnetic field of a magnet, and a diaphragm, which is mechanically coupled to the coil, wherein the magnet produces a magnetic flux density (B), the coil, has an effective length in the magnetic field, and the diaphragm has an area (A). In order to determine a first transfer function Z.sub.M, a first calibration state is set, in which an external sound pressure (p) on the diaphragm is equal to zero. In order to determine a second transfer function Z.sub.C, a second calibration state is set, in which movement of the diaphragm is suppressed. Subsequently, in normal operation the current (I) flowing through the coil and the voltage (U) dropping across the coil are measured and the external sound pressure (p) on the diaphragm is determined using the magnetic flux density (B), the effective length of the coil in the magnetic field of the magnet, the first transfer function, the second transfer function, the area (A) of the diaphragm, the current (I) measured by the measuring device in normal operation, and the voltage (U) measured by the measuring device in normal operation. The present disclosure further relates to a corresponding loudspeaker assembly.

The present application provides a method of audio signal processing. The method comprises obtaining a voice coil direct current resistance of a speaker. The method further comprises obtaining an audio input signal to be input into the speaker. The method further comprises determining an audio input power based on the voice coil direct current resistance and the audio input signal. The method further comprises obtaining a thermal model of the speaker, and determining a transient power threshold based on the audio input power and the thermal model. The method further comprises determining a power constraint gain based on the audio input power and the transient power threshold. The method further comprises obtaining a voice coil temperature of the speaker. The method further comprises determining a temperature constraint gain based on the voice coil temperature and an upper operating temperature limit of the speaker. The method further comprises adjusting the audio input signal based on the power constraint gain and the temperature constraint gain, to obtain a target signal.

A bone conduction speaker is provided herein. The bone conduction speaker may include a magnetic circuit component for providing a magnetic field, a vibration component located in the magnetic field, and a case. At least a part of the vibration component may convert an electrical signal into a mechanical vibration signal. The case may include a case panel facing a human body side and a case back opposite to the case panel, and accommodate the vibration component that causes the case panel and the case back to vibrate. A vibration of the case panel may have a first phase, and a vibration of the case back may have a second phase. When frequencies of the vibration of the case panel and the case back are within 2000 Hz to 3000 Hz, an absolute value of a difference between the first and the second phase(s) may be less than 60 degrees.