799results about "Transducer protection circuits" patented technology

Loudspeakers can be damaged by high drive signals. One reason for this damage is an excess vibration displacement of the coil-diaphragm assembly. This invention describes a novel method for limiting this displacement by a signal processor. In the present invention, a low frequency shelving and notch filter is used to attenuate low frequencies according to a prediction of the loudspeaker displacement. A novel method for calculating coefficient values for a digital implementation of the low frequency shelving and notch filter according to the predicted displacement is described.

A condenser microphone is provided having a transducer element. A diaphragm has an electrically conductive portion. A back-plate has an electrically conductive portion. A DC bias voltage element is operatively coupled to the diaphragm and the back-plate. A collapse detection element is adapted to determine a physical parameter value related to a separation between the diaphragm and the back-plate. A collapse control element is adapted to control the DC bias voltage element based on the determined physical parameter value.

Low-frequency bandwidth extension in the form of dynamic electrical equalization may be applied to loudspeakers so long as the excursion capability of their drive units as well as velocity limits of any port(s) or excursion limits of any associated passive radiator(s), and the power limits of the drive units are not exceeded. The bandwidth extension maximizes low-frequency bandwidth dynamically such that excursion is fully utilized over a range of drive levels, without exceeding the excursion limit. Additional limiting control is available for port air velocity or passive radiator excursion, and loudspeaker drive unit electrical power. The system applies to open back, closed box, vented box, and more complex box constructions consisting of combinations of these elements for loudspeaker designs using design parameters appropriate to each system.

This invention relates to the mechanical protection using digital processing and a predictive estimation of instantaneous displacement of the voice coil in a loudspeaker transducer.

The invention solves the problem of limiting the coil displacement of the transducer by applying a look-a-head based linear or non-linear predictor and a controller operating directly on the displacement signal in order to finally convert back into the incoming signal domain.

Audio transducers (headphones, speakers, microphones) inherently do not accurately reproduce the signal presented to them at the input. This can be compensated for by taking into account the transducer characteristics and transforming the input signal using a digital signal processor (DSP) to counteract the inaccuracies. However, for the compensation to take place, the DSP needs to know the characteristics of the transducer. For systems with built-in transducers (like laptops with internal speakers) the characteristics of the internal speakers can be stored on the hard-drive of the laptop and the DSP can read this data and make the appropriate compensations. Because a transducer (headphone, speaker, microphone) has its own characteristics that need to be compensated for separately, a profile is supplied to the DSP either by a database lookup based on an identification made by the user or transducer itself or by profile information stored on the transducer. Once the characteristics of a transducer are known, many additional DSP algorithms can be applied in order to improve the audio performance and even safety of the system.

A signal-to-noise ratio dependent adaptive spectral subtraction process eliminates noise from noise-corrupted speech signals. The process first pre-emphasizes the frequency components of the input sound signal which contain the consonant information in human speech. Next, a signal-to-noise ratio is determined and a spectral subtraction proportion adjusted appropriately. After spectral subtraction, low amplitude signals can be squelched. A single microphone is used to obtain both the noise-corrupted speech and the average noise estimate. This is done by determining if the frame of data being sampled is a voiced or unvoiced frame. During unvoiced frames an estimate of the noise is obtained. A running average of the noise is used to approximate the expected value of the noise. Spectral subtraction may be performed on a composite noise-corrupted signal, or upon individual sub-bands of the noise-corrupted signal. Pre-averaging of the input signal's magnitude spectrum over multiple time frames may be performed to reduce musical noise.

A circuit and method provides for the protection of transducers from over excursion, particularly for the protection of transducers for audio loudspeakers. A frequency dependent excursion limiter circuit has an initial summing stage followed by a shaping filter stage. A clamping function is provided at the summing stage, or at a separate stage between the summing stage and the shaping filter stage, for clamping the driving signal at a predetermined maximum voltage if the driving signal exceeds the predetermined maximum voltage level. The shaping filter stage provides a frequency response shaping function based on a predetermined frequency response shaping criteria which is related to the frequency dependent excursion limits of the transducers being protected from mechanical overload. An inverse shaping filter function is provided at the initial summing stage by providing feedback from the shaping filter stage, thus eliminating the need for a separate inverse shaping filter circuit before clamping. The inverse shaping filter function allows low level signals below clamping to pass through the circuit unaffected.

A frequency dependent excursion limiter circuit is also provided in the closed loop circuit of servo feedback system for protecting transducers in a servo feedback system from over excursion.

A method of estimating diaphragm excursion of an electrodynamic loudspeaker may be performed using audio signals. An audio output signal may be applied to a voice coil of the electrodynamic loudspeaker through an output amplifier to produce sound. A detected voice coil current and a determined voice coil voltage may be applied to a linear adaptive digital loudspeaker model that has a plurality of adaptive loudspeaker parameters. The parameter values of the adaptive loudspeaker parameters may be computed based on the linear adaptive digital loudspeaker model and applied to a non-linear state-space model of the electrodynamic loudspeaker. For the non-linear state-space model, a predetermined non-linear function may be applied to at least one of the plurality of received parameter values to compute at least one non-linearity compensated parameter value of the adaptive loudspeaker parameters, to determine an instantaneous excursion of the diaphragm.

A headset used as an external louder speaker and a method for adjusting an output of the speaker transducers are disclosed. The headset includes a signal receiver, speaker parts, hinge parts, and amplifiers. The speaker parts change their direction through the hinge parts. The output of speaker transducers is adjusted according to the direction of the speaker parts. When the output of speaker transducers is increased, the speaker parts of the headset are used as an external speaker.

A method of eliminating interference components in a microphone signal by generating a compensation signal and subtracting the compensation signal from the microphone signal. The compensation occurs completely in the frequency domain and the output signal is processed in the frequency domain as well. Measures for reducing the expenditure during the signal processing are specified. For example, advantageous modifications provide that a filter setting, obtained during a preceding speech pause, be used for eliminating interference in a voice signal and/or that the simulation filter be divided into several partial filters for long pulse responses. In particular, the invention is suitable for eliminating interference signal components, e.g., caused by a radio or the like, from a voice input signal in a motor vehicle, the source signal of which is available as reference signal.

A loudspeaker protection system includes a filter arrangement for defining one or more frequency bands of an audio signal, controllable amplifier/attenuator combinations coupled to the filter arrangement, and a processing arrangement coupled to control the amplifier/attenuator combinations, such as to determine audio power in at least one of the frequency bands representing relevant loudspeaker protection information used for selective audio power control in the at least one frequency band. This system has the features for a fast and/or slow thermal protection, as well as for a cone excursion protection, all for a loudspeaker in such a system.

Aspects of the disclosure pertain to a system and method for providing temperature limiting for a voice coil of a speaker. The system and method provide the aforementioned temperature limiting based upon monitoring (e.g., measurement) of an amplifier output signal provided to the speaker. Providing the aforementioned temperature limiting promotes improved protection for the speaker.