WO2023082159A1

WO2023082159A1 - Amplitude limiting apparatus and amplitude limiting method

Info

Publication number: WO2023082159A1
Application number: PCT/CN2021/130175
Authority: WO
Inventors: 鄢展鹏; 帕霍·约尼; 杜亮; 廖文婷; 柯波; 任博
Original assignee: 华为技术有限公司
Priority date: 2021-11-11
Filing date: 2021-11-11
Publication date: 2023-05-19
Also published as: CN117795979A

Abstract

The embodiments of the present application relate to the technical field of audio. Disclosed are an amplitude limiting apparatus and an amplitude limiting method, which alleviate the problem in the prior art of the service life of a loudspeaker being short and even the loudspeaker being damaged due to the fact that the displacement of a diaphragm is too large or the temperature of the loudspeaker is too high. The specific solution is: the amplitude limiting apparatus comprises a prediction circuit, a gain estimation circuit and a multiplier, wherein a first input end of the multiplier is used for receiving an audio signal, an output end of the amplitude limiting apparatus is coupled to an input end of the gain estimation circuit by means of the prediction circuit, and an output from the gain estimation circuit is fed back to a second input end of the multiplier; the prediction circuit is used for predicting the displacement of a diaphragm and/or the temperature of a voice coil of a loudspeaker on the basis of the audio signal which is output by the amplitude limiting apparatus; the gain estimation circuit is used for obtaining a gain estimation value on the basis of an amplitude limiting parameter predicted by the prediction circuit; and the multiplier is used for multiplying the received audio signal by the gain estimation value, so as to obtain an amplitude-limited audio signal, and the output end of the amplitude limiting apparatus outputs the amplitude-limited audio signal.

Description

A limiting device and a limiting method

technical field

The embodiments of the present application relate to the field of audio technology, and in particular, to a limiting device and a limiting method.

Background technique

At present, a loudspeaker is widely used in various electronic products as a sound emitting device. Figure 1 is a schematic diagram of the structure and principle of a loudspeaker, as shown in (a) in Figure 1, the loudspeaker includes a front cover, a dome, a diaphragm, a voice coil, shrapnel, a basin frame, an upper splint, a magnetic steel and a lower splint . The audio signal to be played is wound in the form of an energized conductor on the voice coil, which is located in the loudspeaker's magnetic field system. As shown in (b) in Figure 1, when the current flows through the voice coil, according to the left-hand rule, the voice coil will be affected by the Ampere force F, and the diaphragm connected to the voice coil will be produced under the action of the Ampere force F change in displacement. Due to the packaging design of the speaker, the displacement change of the diaphragm will squeeze the gas in the speaker cavity, causing the speaker to resonate acoustically, thereby emitting sound. That is, the sounding process of the speaker includes the conversion of electricity-force-sound. According to the principle of speaker transduction, if the displacement of the diaphragm is too large, the sound of the speaker will inevitably produce nonlinear distortion, which will reduce the life of the speaker and even damage it. speaker. Moreover, as a kind of transducer, the speaker will generate a lot of heat during the energy conversion process. If the temperature of the voice coil in the speaker is too high, the speaker will also be damaged. Therefore, prolonging the service life of the loudspeaker has become an urgent problem to be solved.

Contents of the invention

Embodiments of the present application provide a limiting device and a limiting method, which can perform limiting control on limiting parameters of a loudspeaker and prolong the service life of the loudspeaker.

In order to achieve the above purpose, the embodiment of the present application adopts the following technical solutions:

According to the first aspect of the embodiments of the present application, a limiting device is provided. The limiting device includes a prediction circuit, a gain estimation circuit, and a multiplier. The first input terminal of the multiplier is used to receive an audio signal, and the output of the limiting device The end is coupled to the input end of the gain estimation circuit through the prediction circuit, the output of the gain estimation circuit is fed back to the second input end of the multiplier, and the output end of the limiting device is used for coupling with the loudspeaker. The prediction circuit is used for predicting the limiting parameter of the loudspeaker based on the audio signal output by the limiting device, and the limiting parameter includes at least one of diaphragm displacement or voice coil temperature. The gain estimation circuit is used to obtain an estimated gain value based on the limiting parameter predicted by the prediction circuit. The multiplier is used to receive the audio signal and the gain estimation value fed back by the gain estimation circuit, and multiply the received audio signal and the gain estimation value to obtain a limited audio signal, and the output terminal of the limiting device outputs the limited audio Signal.

Based on this scheme, the limiting parameter of the loudspeaker is predicted according to the audio signal output by the limiting device, and the gain estimation value is obtained according to the limiting parameter, and the audio signal input to the multiplier is multiplied by the feedback gain estimation value to achieve the purpose of limiting , this scheme adopts the feedback control method to form a closed-loop control system in the limiting device, so the stability is relatively high. Moreover, this program obtains the gain estimate by using the limit parameter (at least one of diaphragm displacement or voice coil temperature), and then uses the gain estimate to limit the audio signal input to the limiter to obtain the limited audio signal, the audio signal is limited so that the amplitude of the limiting parameter is also limited, so the purpose of limiting the diaphragm displacement and/or voice coil temperature can be achieved, and the corresponding diaphragm displacement and/or Voice coil temperature, prolonging the service life of the speaker.

With reference to the first aspect, in a possible implementation manner, the limiting device further includes a saturated limiting circuit, and an output terminal of the multiplier is coupled to an output terminal of the limiting device through the saturated limiting circuit.

Based on this solution, the amplitude of the audio signal output by the limiting device can be limited within the preset threshold range through the saturation limiting circuit. The purpose of limiting the audio signal limited by the multiplier is to protect the circuit.

In combination with the first aspect and the foregoing possible implementation manners, in another possible implementation manner, the prediction circuit includes a displacement prediction circuit, and the displacement prediction circuit is used to output an audio signal based on the Thiele-Small parameter of the loudspeaker and the limiting device, Predict the diaphragm displacement of a loudspeaker. The input parameters of the displacement prediction circuit are voltage parameters or current parameters corresponding to the audio signal output by the limiting device.

The Thiele-Small parameter is a set of parameters defined by people to commemorate the contribution of two scientists, Thiele and Small, to electricity, referred to as the TS parameter. The TS parameter of the loudspeaker is used to measure the electrical performance of the loudspeaker.

Based on this scheme, the diaphragm displacement of the speaker can be predicted through the TS parameter of the speaker and the voltage parameter or current parameter corresponding to the audio signal output by the limiting device, so that the estimated gain value can be obtained according to the diaphragm displacement, and the estimated gain value can be compared with the input After the audio signal of the multiplier is multiplied, the purpose of limiting the audio signal can be achieved, which can prolong the service life of the speaker

In combination with the first aspect and the above possible implementation manner, in another possible implementation manner, the prediction circuit further includes a temperature prediction circuit, and the temperature prediction circuit is used for the audio signal output based on the Thiele-Small parameter of the loudspeaker and the limiting device , to predict the voice coil temperature of the loudspeaker. The input parameter of the temperature prediction circuit is at least one of the voltage parameter or the current parameter corresponding to the audio signal output by the limiting device.

Based on this scheme, at least one of the TS parameters of the loudspeaker and the voltage parameter or current parameter corresponding to the audio signal output by the limiting device can predict the voice coil temperature of the loudspeaker, so that an estimated gain value can be obtained according to the voice coil temperature, and the gain After the estimated value is multiplied by the audio signal input to the multiplier, the purpose of limiting the audio signal can be achieved, which can prolong the service life of the loudspeaker.

With reference to the first aspect and the foregoing possible implementation manner, in another possible implementation manner, when the prediction circuit includes a displacement prediction circuit and a temperature prediction circuit, the displacement prediction circuit and the temperature prediction circuit are connected in parallel.

Based on this scheme, when the prediction circuit includes a displacement prediction circuit and a temperature prediction circuit, the TS parameters of the loudspeaker and the audio signal output by the limiting device can predict the diaphragm displacement and voice coil temperature of the loudspeaker, so that according to the displacement of the diaphragm and the voice coil The temperature can obtain an estimated gain value, and after multiplying the estimated gain value by the audio signal input to the multiplier, the purpose of limiting the audio signal can be achieved, which can prolong the service life of the loudspeaker.

With reference to the first aspect and the foregoing possible implementation manner, in another possible implementation manner, the displacement prediction circuit includes one or more biquad Biquad filters, and the multiple Biquad filters are cascaded.

Based on this scheme, a Biquad filter or cascaded multiple Biquad filters can be used to fit the voltage-displacement transfer function, so that the diaphragm displacement of the loudspeaker can be predicted more accurately.

In combination with the first aspect and the above-mentioned possible implementation, in another possible implementation, the above-mentioned temperature prediction circuit is specifically used according to the Thiele-Small parameter of the speaker, the voltage parameter and the current corresponding to the audio signal output by the limiting device The parameters identify the impedance of the loudspeaker and predict the voice coil temperature of the loudspeaker.

Based on this scheme, the impedance of the speaker is identified by using the feedback voltage and feedback current obtained in real time at both ends of the speaker chip, and the approximate linear relationship between the real-time temperature of the voice coil in the speaker and the actual impedance is used to predict the voice coil temperature of the speaker , which can improve the stability of the limiter control.

In combination with the first aspect and the above-mentioned possible implementation, in another possible implementation, the above-mentioned gain estimation circuit is specifically configured to: when the above-mentioned limiting parameter is higher than the first preset threshold, the gain The estimated value is decreased by a first value; when the limiting parameter is lower than a second preset threshold, the estimated value of the gain at the previous sampling point is increased by a second value. Wherein, the first preset threshold is greater than or equal to the second preset threshold.

Based on this scheme, the gain estimate can be lowered when the diaphragm displacement is large and/or the voice coil temperature is high, so the multiplier can achieve The purpose of limiting is to reduce the displacement of the diaphragm and/or the temperature of the voice coil corresponding to the limited audio signal, so as to prolong the service life of the speaker. Moreover, the limiting device provided by the present application has better stability and lower time delay, and can improve the performance of the loudspeaker. In this solution, when the displacement of the diaphragm is small and/or the temperature of the voice coil is low, the estimated value of the gain is raised to restore the real audio signal.

With reference to the first aspect and the foregoing possible implementation manner, in another possible implementation manner, the above estimated gain value is greater than 0 and less than or equal to 1.

Based on this scheme, by multiplying the estimated gain value greater than 0 and less than or equal to 1 with the audio signal input to the multiplier, not only the purpose of limiting the audio signal can be achieved, but also the harmonics caused by the clipping effect can be reduced , to improve the signal-to-noise ratio.

In combination with the first aspect and the above-mentioned possible implementation, in another possible implementation, the above-mentioned gain estimation circuit includes a first selector, a subtractor, and an adder, and the output terminal of the first selector is the output terminal of the gain estimation circuit. output terminal, the output terminal of the first selector is coupled to the first input terminal of the subtractor through the first flip-flop, the second input terminal of the subtractor inputs the first value, and the output terminal of the subtractor is coupled to the first input terminal of the first selector an input terminal. The output terminal of the first selector is coupled to the first input terminal of the adder through the second flip-flop, the second input terminal of the adder inputs the second value, and the output terminal of the adder is coupled to the second input terminal of the first selector . The first selector is used for inputting the output of the gain estimation circuit to the first flip-flop or the second flip-flop.

Based on this scheme, the first selector can input the output of the gain estimation circuit to the first flip-flop or the second flip-flop, so that when the limiting parameter is high, the gain estimation value of the previous sampling point can be reduced by the first value. When the clipping parameter is low, the gain estimate at the previous sampling point is increased by a second value. Since the circuit structure of the gain estimating circuit is relatively simple, the time delay of the limiting device is relatively low.

With reference to the first aspect and the above possible implementation manner, in another possible implementation manner, the first selector is specifically configured to: when the limiting parameter is higher than the first preset threshold, the gain estimation output by the gain estimation circuit Input the value into the first flip-flop; when the limiting parameter is lower than the first preset threshold, input the estimated gain value output by the gain estimation circuit into the second flip-flop. The first flip-flop and the second flip-flop are used to delay the estimated gain value output by the gain estimation circuit. A subtractor, configured to reduce the estimated gain value delayed by the first trigger by a first value. An adder, configured to increase the estimated gain value delayed by the second flip-flop by a second value.

Based on this solution, the gain estimation circuit may reduce the estimated gain value of the previous sampling point by a first value when the limiting parameter is higher than the first preset threshold. When the limiting parameter is lower than the first preset threshold, the estimated value of the gain at the previous sampling point is increased by a second value. Since the circuit structure of the gain estimating circuit is relatively simple, the time delay of the limiting device is relatively low.

In combination with the first aspect and the above-mentioned possible implementation, in another possible implementation, the above-mentioned gain estimation circuit further includes a second selector, a third selector, and a fourth selector, and the output terminal of the subtractor is connected to the second The first input end of the selector is connected, the second input end of the second selector is input with a preset minimum gain, and the output end of the second selector is connected with the first input end of the first selector. The output terminal of the adder is connected with the first input terminal of the third selector, the second input terminal of the third selector is connected with the output terminal of the first selector, and the output terminal of the third selector is connected with the first input terminal of the fourth selector. One input connection. The second input end of the fourth selector inputs a preset maximum gain, and the output end of the fourth selector is connected to the second input end of the first selector.

Based on this solution, the gain estimation circuit can reduce the estimated gain value of the previous sampling point by a first value to obtain an adjusted estimated gain value when the limiting parameter is greater than or equal to the first preset threshold value, and the adjusted The gain estimate is not less than a preset minimum gain. When the limiting parameter is less than the first preset threshold, the estimated gain value of the previous sampling point is increased by a second value to obtain an estimated gain value after adjustment, and the estimated estimated gain value after adjustment is not greater than the preset maximum gain. Moreover, the circuit structure of the gain estimation circuit is relatively simple, so that the time delay of the limiting device is relatively low.

In combination with the first aspect and the above possible implementation manner, in another possible implementation manner, the above second selector is configured to output the value output by the subtractor when the value output by the subtractor is greater than a preset minimum gain; When the value output by the subtractor is less than the preset minimum gain, the preset minimum gain is output. The third selector is used to output the value output by the adder when the estimated gain value delayed by the second trigger is less than the preset maximum gain; the estimated gain value delayed by the second trigger is greater than the preset maximum gain; When the maximum gain is set, the maximum gain output will be preset. The fourth selector is used to output the output value of the third selector when the output of the third selector is less than the preset maximum gain; when the output of the third selector is greater than the preset maximum gain, the preset maximum gain output.

Based on this solution, the adjusted estimated gain value can be made not less than the preset minimum gain through the second selector. Through the third selector and the fourth selector, the adjusted estimated gain value may not be greater than the preset maximum gain. Moreover, the circuit structure of the gain estimation circuit is relatively simple, so that the time delay of the limiting device is relatively low.

With reference to the first aspect and the above possible implementation manner, in another possible implementation manner, the sum of the time when the prediction circuit predicts the clipping parameter and the time when the gain estimation circuit calculates the estimated gain value is less than or equal to the sampling period.

Based on this scheme, since the sum of the time for predicting the limiting parameter and the time for calculating the estimated gain value is less than or equal to the sampling period, that is, the moment when the gain estimated value is calculated by the gain estimation circuit in this application minus the time when the audio signal enters the limiting device is less than or equal to the sampling period, so the time delay of the limiting device provided in the embodiment of the present application is relatively small when performing limiting processing on the audio signal.

In a second aspect of the embodiments of the present application, a limiting method is provided, the limiting method includes: first, predicting the limiting parameters of the loudspeaker based on the first audio signal, the limiting parameters include diaphragm displacement or voice coil temperature At least one type; the first audio signal is an audio signal output to the speaker. Then, based on the clipping parameters of the loudspeaker, a gain estimate is obtained. Finally, the second audio signal is multiplied by the estimated gain value to obtain a limited audio signal, and the second audio signal is the input original audio signal.

With reference to the second aspect, in a possible implementation manner, the prediction of the limiting parameter of the loudspeaker based on the first audio signal includes: predicting the diaphragm of the loudspeaker based on the Thiele-Small parameter of the loudspeaker and the audio parameter of the first audio signal. displacement. The audio parameters of the first audio signal include voltage parameters or current parameters corresponding to the first audio signal.

With reference to the second aspect and the above possible implementation manner, in another possible implementation manner, the prediction of the limiting parameter of the loudspeaker based on the first audio signal further includes: Thiele-Small parameters based on the loudspeaker and the first audio signal Audio parameter that predicts the voice coil temperature of a loudspeaker. The audio parameter of the first audio signal includes at least one of a voltage parameter or a current parameter corresponding to the first audio signal.

In combination with the second aspect and the above possible implementation manner, in another possible implementation manner, the obtaining the estimated gain value based on the limiting parameter of the speaker includes: when the limiting parameter of the loudspeaker is higher than the first preset threshold , reduce the estimated gain value of the previous sampling point by a first value; when the limiting parameter of the loudspeaker is lower than a second preset threshold, increase the estimated gain value of the previous sampling point by a second value; wherein, the first preset The threshold is set to be greater than or equal to the second preset threshold.

With reference to the second aspect and the foregoing possible implementation manner, in another possible implementation manner, the above estimated gain value is greater than 0 and less than or equal to 1.

With reference to the second aspect and the foregoing possible implementation manner, in another possible implementation manner, the sum of the time for predicting the limiting parameter and the time for determining the estimated gain value is less than or equal to the sampling period.

For the effect description of the second aspect above, reference may be made to the effect description of the first aspect, and details are not repeated here.

According to the third aspect of the embodiments of the present application, there is provided a limiting device, the limiting device includes a processor and an interface circuit, the processor receives or sends a signal through the interface circuit; the processor is used to execute the signal stored in the memory The computer program in the present invention enables the clipping device to perform the method described in the second aspect above.

According to the fourth aspect of the embodiments of the present application, a computer-readable storage medium is provided. Computer program code is stored in the computer-readable storage medium. When the computer program code is run on a computer or a processor, the The computer or the processor executes the method described in the second aspect above.

A fifth aspect of the embodiments of the present application provides a computer program product, the program product stores program instructions, and when the program instructions are executed by a computer or a processor, the method described in the second aspect above is realized.

The sixth aspect of the embodiments of the present application provides an audio system, the audio system includes an amplifier, a speaker, and the limiting device as described in the first aspect above, and the limiting device is coupled to the speaker.

Description of drawings

FIG. 1 is a schematic diagram of the structure and principle of a loudspeaker provided by the embodiment of the present application;

FIG. 2A is a schematic structural diagram of a clipping device provided in an embodiment of the present application;

Fig. 2B is a schematic structural diagram of another limiting device provided in the embodiment of the present application

Fig. 3 is a schematic structural diagram of another limiting device provided in the embodiment of the present application;

Fig. 4 is the structural representation of a kind of Biquad filter that the embodiment of the present application provides;

FIG. 5 is a schematic flow chart of an impedance identification method provided in an embodiment of the present application;

FIG. 6 is a schematic structural diagram of a gain estimation circuit provided in an embodiment of the present application;

FIG. 7 is a schematic structural diagram of another gain estimation circuit provided by an embodiment of the present application;

FIG. 8 is a schematic flow chart of a clipping method provided by an embodiment of the present application.

Detailed ways

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. In this application, "at least one" means one or more, and "multiple" means two or more. "And/or" describes the association relationship of associated objects, indicating that there may be three types of relationships, for example, A and/or B, which can mean: A exists alone, A and B exist at the same time, and B exists alone, where A, B can be singular or plural. The character "/" generally indicates that the contextual objects are an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (unit) of a, b or c can represent: a, b, c, a and b, a and c, b and c, or, a and b and c, wherein a, b and c can be single or multiple. In addition, in order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, words such as "first" and "second" are used to distinguish the same or similar items with basically the same function and effect, Those skilled in the art can understand that words such as "first" and "second" do not limit the quantity and execution order. For example, "first" in the first numerical value and "second" in the second numerical value in the embodiments of the present application are only used to distinguish different numerical values. The first, second, etc. descriptions that appear in the embodiments of this application are only for illustration and to distinguish the description objects, and there is no order, nor does it represent a special limitation on the number of devices in the embodiments of this application, and cannot constitute a limitation on the number of devices in this application. Any limitations of the examples.

It should be noted that, in this application, words such as "exemplary" or "for example" are used as examples, illustrations or illustrations. Any embodiment or design described herein as "exemplary" or "for example" is not to be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete manner.

When the displacement of the diaphragm of the speaker is too large or the temperature of the voice coil is too high, the life of the speaker will be reduced, and the speaker may even be damaged. In order to alleviate the problem that the life of the speaker is affected by the excessive displacement of the diaphragm in the speaker or the temperature in the speaker is too high, or even the loss of the speaker, the embodiment of the present application provides a limiting device, which can control the displacement of the diaphragm of the speaker or Limiting control is performed on the temperature of the voice coil to prolong the service life of the loudspeaker, and the limiting device provided by the present application has better stability and lower time delay, which can improve the performance of the loudspeaker.

An embodiment of the present application provides a limiting device, as shown in Figure 2A, the limiting device includes a prediction circuit, a gain estimation circuit and a multiplier, the first input a of the multiplier is the input end of the limiting device, and the limiting The input terminal of the device is used to receive the audio signal, the output terminal e of the limiting device is coupled to the input terminal c of the gain estimation circuit through the prediction circuit, the output terminal of the gain estimation circuit is fed back to the second input terminal d of the multiplier, and the limiting device The output terminal is used to couple with the loudspeaker.

Optionally, as shown in FIG. 2B , the limiting device may further include a saturated limiting circuit, and the output terminal b of the multiplier is coupled to the output terminal e of the limiting device through the saturated limiting circuit. The saturation limiting circuit can limit the amplitude of the audio signal output by the limiting device within a preset threshold range. The limited audio signal output from the output terminal of the limiting device may be an output audio signal limited by a saturated limiting circuit.

It should be noted that if the audio signal is clipped directly using the saturation clipping circuit, the audio signal will be clipped and a large number of harmonics will be generated. However, in the embodiment of the present application, the estimated gain value is fed back by the prediction circuit and the gain estimation circuit, and the audio signal is limited according to the estimated gain value, so as to protect the loudspeaker. The limited signal is then processed by a saturated limiting circuit and then output to the speaker. That is to say, the limit implemented by multiplying the audio signal by the estimated gain value in the limiter is to protect the loudspeaker, and the limit performed by the saturation limiter circuit on the audio signal limited by the multiplier is to protect the circuit.

Optionally, as shown in FIG. 2B , the output terminal e of the saturation limiter circuit may be coupled to the speaker through an amplifier. The amplifier is used to amplify the audio signal output by the saturation limiting circuit and input it to the speaker, and the speaker receives the amplified signal and plays the sound.

The prediction circuit is used for predicting the limiting parameter of the loudspeaker based on the audio signal output by the limiting device, and the limiting parameter includes at least one of diaphragm displacement or voice coil temperature.

Optionally, the prediction circuit may include a displacement prediction circuit for estimating the displacement of the diaphragm, a temperature prediction circuit for estimating the temperature of the voice coil, a displacement prediction circuit for estimating the displacement of the diaphragm, and a circuit for estimating Temperature prediction circuit for voice coil temperature. The embodiment of the present application does not limit the specific structure of the prediction circuit.

Exemplarily, in the case where the prediction circuit includes a displacement prediction circuit, the limiting parameters include a diaphragm displacement, and the displacement prediction circuit is used to predict the loudspeaker based on the TS (Thiele-Small) parameter of the loudspeaker and the audio signal output by the limiting device. diaphragm displacement. In the case that the predicting circuit includes a temperature predicting circuit, the limiting parameter includes voice coil temperature, and the temperature predicting circuit is used to predict the voice coil temperature of the speaker based on the TS parameter of the speaker and the audio signal output by the limiting device. In the case where the prediction circuit includes a displacement prediction circuit and a temperature prediction circuit, the limiting parameters include diaphragm displacement and voice coil temperature, and the displacement prediction circuit is used to predict the vibration of the speaker based on the TS parameters of the speaker and the audio signal output by the limiting device. The membrane displacement and temperature prediction circuit is used to predict the voice coil temperature of the speaker based on the TS parameter of the speaker and the audio signal output by the limiting device. As shown in FIG. 3 , when the prediction circuit includes a displacement prediction circuit and a temperature prediction circuit, the displacement prediction circuit and the temperature prediction circuit are connected in parallel. Both the input end of the displacement prediction circuit and the input end of the temperature prediction circuit are connected to the output end e of the limiter, and the output ends of the displacement prediction circuit and the output end of the temperature prediction circuit are coupled to the input end c of the gain estimation circuit.

The Thiele-Small parameter is a set of parameters defined by people to commemorate the contribution of two scientists, Thiele and Small, to electricity, referred to as the TS parameter. TS parameters are used to measure the electrical performance of loudspeakers. The TS parameters of the loudspeaker include but are not limited to the lowest resonance frequency f ₀ of the loudspeaker, the DC impedance _Re of the coil, the equivalent mass of the vibration system M _ms , the total damping coefficient of the loudspeaker Q _ts , the magnetic factor Bl, the mechanical quality factor of the loudspeaker Q _ms and other parameters . The embodiment of the present application does not limit the specific type of the TS parameter of the loudspeaker.

The method of predicting the displacement of the diaphragm of the speaker by the displacement prediction circuit and the method of predicting the temperature of the voice coil of the speaker by the temperature prediction circuit will be introduced respectively below.

When the displacement prediction circuit predicts the displacement of the diaphragm of the loudspeaker, the input parameter of the displacement prediction circuit may be a voltage parameter or a current parameter corresponding to the audio signal output by the limiting device. In the embodiment of the present application, the input parameters of the displacement prediction circuit are used as the voltage parameters corresponding to the audio signal output by the limiting device. The TS parameters of the speaker include the lowest resonance frequency f ₀ of the speaker, the DC impedance _Re of the coil, and the equivalent mass M of the vibration system. Taking _ms , total loudspeaker damping coefficient Q _ts , and magnetic factor Bl as examples, the method for predicting diaphragm displacement by the displacement prediction circuit is introduced.

Optionally, the diaphragm displacement can be estimated according to the voltage-displacement transfer function of the loudspeaker in the Laplace domain. The voltage-displacement transfer function is as follows:

Among them, H(S) is the voltage-displacement transfer function, X(S) is the diaphragm displacement in the frequency domain, U(S) is the feedback voltage in the frequency domain, f ₀ is the lowest resonant frequency of the loudspeaker, Re _is the direct current of the coil Impedance, M _ms is the equivalent mass of the vibration system, Q _ts is the total damping coefficient of the loudspeaker, Bl is the magnetic force factor.

Optionally, when the displacement prediction circuit predicts the diaphragm displacement of the loudspeaker, the displacement prediction circuit can use a biquad Biquad filter to fit the above-mentioned voltage-displacement transfer function, or can use multiple Biquad filter cascade fittings The above voltage-displacement transfer function, where a Biquad filter can be realized by the structure shown in Figure 4. That is, the displacement prediction circuit in FIG. 3 may include one Biquad filter, or may include multiple cascaded Biquad filters shown in FIG. 4 . The input data in Fig. 4 is the voltage parameter of the audio signal output by the limiting device, and the voltage parameter can be the feedback voltage obtained from both ends of the speaker chip in real time, the output data is the predicted diaphragm displacement, and D is used to realize a The D flip-flop of the audio sampling point delay, b0, b1 and b2 are the feedforward coefficients, a1 and a2 are the feedback coefficients, the feedforward coefficient and the feedback coefficient can be calculated according to the above TS parameters, and the filter structure shown in Figure 4 can be Realizing the above-mentioned voltage-displacement transfer function H(S), the diaphragm displacement can be predicted.

It can be understood that when the displacement prediction circuit predicts the displacement of the diaphragm, multiple Biquad filters shown in Figure 4 can be cascaded to fit the voltage-displacement transfer function, or the Chebyshev filter can be used to fit the voltage-displacement transfer function, and a multi-order infinite impulse response filter can be used to fit the voltage-displacement transfer function, and a multi-order finite impulse response can be used to fit the voltage-displacement transfer function. The embodiment of the present application does not limit the specific method for the displacement prediction circuit to predict the diaphragm displacement of the loudspeaker.

When the temperature prediction circuit predicts the voice coil temperature of the loudspeaker, the input parameter of the temperature prediction circuit may be at least one of the voltage parameter or the current parameter corresponding to the audio signal output by the limiting device. In the embodiment of the present application, the TS parameters of the speaker include the lowest resonant frequency f ₀ of the speaker, the DC impedance _Re of the coil, the equivalent mass of the vibration system M _ms , the mechanical quality factor of the speaker Q _ms and the magnetic factor Bl, and the input parameters of the temperature prediction circuit Including the voltage parameter and current parameter corresponding to the audio signal output by the limiting device as an example, the method for predicting the voice coil temperature of the speaker by the temperature prediction circuit is introduced.

Optionally, since various parameters of the loudspeaker change with changes in the environment (eg, ambient temperature, input voltage), real-time modeling of the loudspeaker may be performed according to the environmental parameters. At a room temperature of 25 degrees Celsius, by testing the parameters of the TS model, the initial impedance curve of the speaker in the Laplace domain is obtained as follows:

Among them, f ₀ is the lowest resonance frequency of the speaker, _Re is the DC impedance of the coil, M _ms is the equivalent mass of the vibration system, Q _ms is the mechanical quality factor of the speaker, and Bl is the magnetic force factor.

Suppose that the voltage parameter of the audio signal output by the limiting device is u(t), the current parameter is i(t), u(t) and i(t) can be the feedback voltage and the feedback current obtained in real time from both ends of the speaker chip, Use u(t) and i(t) for loudspeaker impedance identification.

Optionally, when the temperature prediction circuit predicts the temperature of the voice coil, it may use a normalized least mean square (NLMS) algorithm to identify the above Z(s) online. As shown in Figure 5, the impedance curve Z ₀ (S) of the speaker is initialized, and the deviation e(t)=u ₍ t)-IFFT(FFT(i(t))*Z ₀ (S)), and then perform Fourier transform on the deviation e(t) to get E(S)=FFT(e(t)), according to

Get the updated impedance Z(S), where ||I(S)|| ₂ means to find the second norm for the current I(S) in the frequency domain, and further judge whether the impedance identification result Z(S) is convergent, and then When the impedance identification result Z(S) converges, an updated impedance curve of the loudspeaker is obtained.

Since the real-time temperature of the voice coil in the speaker and the actual impedance can be approximately considered to have the following linear relationship:

T＝T ₀ +α(||Z(S)||-||Z ₀ (S)||);

Among them, T ₀ is the normal temperature of 25 degrees Celsius, Z ₀ (S) is the initial impedance, Z(S) is the impedance identification result, and α is the temperature sensitivity coefficient of the speaker. The real-time temperature T can be obtained according to the impedance identification results Z(S), initial impedance Z ₀ (S), T ₀ and α in Fig. 5 .

When the environment (for example, input voltage, ambient temperature) changes, the TS parameters of the loudspeaker may deviate from the parameters obtained by normal temperature and small signal tests. Therefore, here, the impedance of the speaker is identified by using the feedback voltage and feedback current obtained in real time at both ends of the speaker chip, and the approximate linear relationship between the real-time temperature of the voice coil in the speaker and the actual impedance is used to predict the voice coil temperature of the speaker , which can improve the stability of the limiter control.

Optionally, when the temperature prediction circuit predicts the voice coil temperature, it can use impedance identification to predict the voice coil temperature, or model the DC resistance to predict the voice coil temperature. The embodiment of the present application does not limit the specific method for predicting the temperature of the voice coil by the temperature prediction circuit. For example, the temperature prediction circuit can predict the temperature of the voice coil according to the relationship between real-time temperature and resistance T(t)=T(0)+α(R _e (t)−R _e ). Among them, T(0) is the normal temperature of 25 degrees Celsius, _Re (t) is the DC resistance calculated in real time, _Re is the initial resistance, and α is the temperature sensitivity coefficient of the speaker.

The gain estimation circuit is used to obtain an estimated gain value based on the limiting parameter predicted by the prediction circuit.

The gain estimation circuit is specifically used to reduce the gain estimation value obtained at the previous sampling point by a first value when the clipping parameter predicted by the prediction circuit is higher than the first preset threshold value, and output the adjusted gain estimation value to the multiplier device. When the limiting parameter predicted by the prediction circuit is lower than the second preset threshold, the estimated gain value obtained at the previous sampling point is increased by a second value, and the adjusted estimated gain value is output to the multiplier. The first preset threshold is greater than or equal to the second preset threshold. The first numerical value may be the same as the second numerical value, or may be different from the second numerical value. For example, the first numerical value may be greater than the second numerical value, may also be smaller than the second numerical value, and may also be equal to the second numerical value.

Exemplarily, for the audio signal of the first sampling point, an initial gain estimation value can be set, and the limiting device multiplies the audio signal of the first sampling point by the initial gain estimation value to obtain a limited audio signal. The output terminal of the amplitude device outputs the limited audio signal. If the limiting parameter predicted by the predicting circuit based on the limited audio signal is higher than the first preset threshold, the gain estimating circuit adjusts the initial estimated gain value downward to obtain a first estimated gain value. If the limiting parameter predicted by the predicting circuit based on the limited audio signal is lower than the second preset threshold, the gain estimating circuit adjusts the initial estimated gain value upward to obtain a first estimated gain value. For the audio signal at the second sampling point, the limiting device multiplies the audio signal at the second sampling point with the estimated gain value (first estimated gain value) obtained at the previous sampling point to obtain a limited audio signal. If the limiting parameter predicted by the prediction circuit based on the limited audio signal is higher than the first preset threshold, the gain estimation circuit adjusts the estimated gain value obtained at the previous sampling point (the first estimated gain value) downward to obtain the second Gain estimates. If the limiting parameter predicted by the prediction circuit based on the limited audio signal is lower than the second preset threshold, the gain estimation circuit adjusts the gain estimation value obtained at the previous sampling point (the first gain estimation value) upward to obtain the second gain estimated value. By analogy, the gain estimation circuit can continuously adjust the gain estimation value based on the limiting parameter predicted by the prediction circuit. The embodiment of the present application does not limit the specific value of the initial gain estimation value, and the value of the initial gain estimation value may be set to 1, or may be set to other values greater than 0 and less than or equal to 1.

Optionally, the estimated gain value adjusted by the gain estimation circuit based on the limiting parameter may not be higher than the maximum gain, nor less than the minimum gain. In the embodiment of the present application, the first value, the second value, the first preset threshold, the Specific values of the two preset thresholds, the maximum gain and the minimum gain are not limited. The maximum gain and minimum gain can be preset values.

Exemplarily, in the case that the prediction circuit includes a displacement prediction circuit, the gain estimation circuit may obtain an estimated gain value based on the diaphragm displacement predicted by the displacement prediction circuit. When the diaphragm displacement predicted by the displacement prediction circuit is relatively large, the gain estimation circuit reduces the estimated gain value of the previous sampling point by a first value. When the diaphragm displacement predicted by the displacement prediction circuit is small, the gain estimation circuit increases the gain estimation value of the previous sampling point by a second value. It should be noted that, in the embodiment of the present application, the estimated gain value at the previous sampling point is the estimated gain value output by the gain estimation circuit at the previous sampling point.

Exemplarily, when the prediction circuit includes a temperature prediction circuit, the gain estimation circuit can obtain an estimated gain value based on the voice coil temperature predicted by the temperature prediction circuit. When the temperature of the voice coil predicted by the temperature prediction circuit is high, the estimated value of the gain at the previous sampling point is reduced by a first value. When the temperature of the voice coil predicted by the temperature prediction circuit is low, the estimated value of the gain at the previous sampling point is increased by a second value. It can be understood that the preset threshold for determining whether the voice coil temperature is higher or lower may be the same as or different from the preset threshold for determining whether the diaphragm displacement is larger or smaller.

Optionally, the estimated value of the gain is a value greater than 0 and less than or equal to 1.

FIG. 6 is a schematic structural diagram of a gain estimation circuit provided by an embodiment of the present application. As shown in FIG. 6 , taking the same example as the first preset threshold and the second preset threshold, the gain estimation circuit includes a first selector , MUX0), subtractor and adder, the output end of the first selector MUX0 is the output end of the gain estimation circuit, the output end of the first selector MUX0 is coupled to the first input end of the subtractor through the first flip-flop D1, The second input terminal of the subtractor inputs the first value, and the output terminal of the subtractor is coupled to the first input terminal 0 of the first selector MUX0. The output terminal of the first selector MUX0 is coupled to the first input terminal of the adder through the second flip-flop D2, the second input terminal of the adder inputs the second value, and the output terminal of the adder is coupled to the first input terminal of the first selector MUX0. Two input terminals 1.

The first selector MUX0 is used for inputting the output of the gain estimation circuit to the first flip-flop D1 or the second flip-flop D2.

As shown in FIG. 6 , the first selector MUX0 is specifically configured to input the estimated gain value output by the gain estimation circuit into the first flip-flop D1 when the limiting parameter is greater than or equal to the first preset threshold. When the limiting parameter is smaller than the first preset threshold, the estimated gain value output by the gain estimation circuit is input to the second flip-flop D2.

The first flip-flop D1 and the second flip-flop D2 are used to delay the estimated gain value output by the gain estimation circuit. The first flip-flop D1 and the second flip-flop D2 can implement a delay of one audio sampling point.

A subtractor, configured to reduce the estimated gain value delayed by the first flip-flop D1 by a first value. The estimated gain value delayed by the first flip-flop D1 may be the estimated gain value of the previous sampling point.

An adder, configured to increase the estimated gain value delayed by the second flip-flop D2 by a second value.

The gain estimation circuit shown in FIG. 6 may reduce the estimated gain value of the previous sampling point by a first value when the limiting parameter is greater than or equal to a first preset threshold. When the limiting parameter is smaller than the first preset threshold, the estimated value of the gain at the previous sampling point is increased by a second value.

Optionally, as shown in FIG. 7, the gain estimation circuit may further include a second selector MUX1, a third selector MUX2 and a fourth selector MUX3, the output end of the subtractor is connected to the first input end of the second selector MUX1 1 connection, the second input terminal 0 of the second selector MUX1 inputs the preset minimum gain, and the output terminal of the second selector MUX1 is connected with the first input terminal 0 of the first selector. The output terminal of the adder is connected with the first input terminal 1 of the third selector MUX2, the second input terminal 0 of the third selector MUX2 is connected with the output terminal of the first selector MUX0, and the output terminal of the third selector MUX2 is connected with The first input terminal 1 of the fourth selector MUX3 is connected, the second input terminal 0 of the fourth selector MUX3 inputs the preset maximum gain, the output terminal of the fourth selector MUX3 is connected with the second input terminal 1 of the first selector MUX0 connect.

The second selector MUX1 is used to output the value output by the subtractor when the value output by the subtractor is greater than the preset minimum gain. When the value output by the subtractor is less than or equal to the preset minimum gain, the preset minimum gain is output.

The third selector MUX2 is used to output the value output by the adder when the estimated gain value delayed by the second flip-flop D2 is less than the preset maximum gain. When the estimated gain value delayed by the second flip-flop D2 is greater than or equal to the preset maximum gain, the preset maximum gain is output. The estimated gain value delayed by the second flip-flop D2 may be the estimated gain value of the previous sampling point.

The fourth selector MUX3 is configured to output the output value of the third selector MUX2 when the output of the third selector MUX2 is less than a preset maximum gain. When the output of the third selector MUX2 is greater than or equal to the preset maximum gain, the preset maximum gain will be output.

The gain estimation circuit shown in FIG. 7 can reduce the gain estimation value of the previous sampling point by a first value to obtain an adjusted gain estimation value when the limiting parameter is greater than or equal to a first preset threshold value, and the adjusted The gain estimate is not less than a preset minimum gain. When the limiting parameter is less than the first preset threshold, the estimated gain value of the previous sampling point is increased by a second value to obtain an estimated gain value after adjustment, and the estimated estimated gain value after adjustment is not greater than the preset maximum gain.

In the following, the first value and the second value are both 0.1, the initial gain estimate is 0.95, the preset maximum gain is 1, the preset minimum gain is 0.1, and the first preset threshold and the second preset threshold are the same as an example. The specific functions of the gain estimation circuit shown in Fig. 7 are introduced.

For example, referring to FIG. 2A or FIG. 2B , as shown in FIG. 7 , for the audio signal input at the first sampling point, the limiting device multiplies the audio signal by an initial gain estimate value of 0.95 to obtain a limited audio signal. If the limiting parameter predicted by the prediction circuit based on the limited audio signal is lower than the first preset threshold, the second input is an estimated gain value (an initial estimated gain value) of 0.95 at the first sampling point. Since the value 0.95 of the second input is less than the preset maximum gain of 1, the output of MUX2 is 0.95 plus the second value 0.1, that is, the value of the third input of MUX3 is 1.05. Since the value 1.05 of the third input is greater than the preset maximum gain 1, the output of MUX3 is the preset maximum gain 1, that is, the gain estimation value output by the gain estimation circuit is 1, and the gain estimation value 1 is obtained from the first sampling point Gain estimates.

For another example, in combination with FIG. 2A or FIG. 2B, as shown in FIG. 7, for the audio signal input at the second sampling point, the limiter multiplies the audio signal with the estimated gain value 1 obtained at the first sampling point to obtain Clipped audio signal. If the limiting parameter predicted by the prediction circuit based on the limited audio signal is higher than the first preset threshold, the value of the first input is the gain estimate value 1 obtained at the first sampling point minus the first value 0.1, that is, the first Enter a value of 0.9. Since the value of the first input is 0.9 greater than the preset minimum gain of 0.1, the output of MUX1 is 0.9, that is, the estimated gain value output by the gain estimation circuit is 0.9, and the estimated gain value 0.9 is the estimated gain value obtained at the second sampling point .

For another example, in combination with FIG. 2A or FIG. 2B, as shown in FIG. 7, for the audio signal input at the third sampling point, the limiter multiplies the audio signal with the estimated gain value 0.9 obtained at the second sampling point to obtain Clipped audio signal. If the limiting parameter predicted by the prediction circuit based on the limited audio signal is higher than the first preset threshold, the value of the first input is the estimated gain value of the second sampling point 0.9 minus the first value 0.1, that is, the first input The value of is 0.8. Since the value of the first input is 0.8 greater than the preset minimum gain of 0.1, the output of MUX1 is 0.8, that is, the estimated gain value output by the gain estimation circuit is 0.8, and the estimated gain value 0.8 is the estimated gain value obtained at the third sampling point . By analogy, the gain estimation circuit can continuously adjust the gain estimation value based on the clipping parameter predicted by the prediction circuit.

It can be understood that when the gain estimation circuit adopts the circuit structure shown in FIG. 6 or FIG. 7, since the circuit structure of the gain estimation circuit shown in FIG. 6 or FIG. technical effect.

Exemplarily, in the case where the prediction circuit includes a displacement prediction circuit and a temperature prediction circuit, the gain estimation circuit may be based on the diaphragm displacement predicted by the displacement prediction circuit, the voice coil temperature predicted by the temperature prediction circuit, and the first weight corresponding to the diaphragm displacement , and the second weight corresponding to the voice coil temperature to obtain the gain estimate. It can be understood that the values of the first weight and the second weight are related to parameters such as the degree of influence of diaphragm displacement and voice coil temperature on the life of the speaker in practical applications, and the specific structure of the speaker.

For example, if the first weight corresponding to the diaphragm displacement is 0.6, the second weight corresponding to the voice coil temperature is 0.4, the estimated value corresponding to the diaphragm displacement of the previous sampling point is 0.2, and the estimated value corresponding to the voice coil temperature of the previous sampling point is 0.3 as an example. If the displacement of the diaphragm predicted by the displacement prediction circuit is small, the estimated value corresponding to the diaphragm displacement at the previous sampling point of 0.2 is increased by the second value 0.1 to obtain the first estimated value of 0.3. If the voice coil temperature predicted by the temperature prediction circuit is low, the estimated value corresponding to the diaphragm displacement at the previous sampling point is 0.3 and the second value is increased by 0.1 to obtain a second estimated value of 0.4, and the estimated gain value obtained by the gain estimation circuit is 0.6 *0.3+0.4*0.4=0.34.

The embodiment of the present application does not limit the specific circuit structure of the gain estimation circuit, any one can realize the limiter parameter is lowered when the limiter parameter is high, and the limiter parameter is increased when the limiter parameter is low All gain estimation circuits are within the scope of protection of the present application, and FIG. 6 and FIG. 7 are only illustrative circuit structures of a gain estimation circuit.

The multiplier is used to receive the audio signal and the estimated gain value fed back by the gain estimation circuit, and multiply the audio signal by the estimated gain value to obtain a limited audio signal. The output terminal of the limiting device outputs the limited audio signal.

The audio signal received by the multiplier is an audio signal input to the limiting device, and the audio signal input to the limiting device is an unlimited audio signal. The unlimited audio signal may be a downlink audio signal processed by a processing unit (for example, a noise reduction unit), may also be an audio signal collected from a sensor, may also be an audio signal released from multimedia, and the like. The embodiment of the present application does not limit which device the audio signal received by the multiplier is output from, and is specifically related to the application scenario of the limiting device.

As shown in Figure 3, taking the prediction circuit including a displacement prediction circuit and a temperature prediction circuit as an example, after the gain estimation circuit obtains the gain estimation value according to the diaphragm displacement predicted by the displacement prediction circuit and the voice coil temperature predicted by the temperature prediction circuit, the gain The estimated value is fed back to the multiplier, and the multiplier multiplies the received audio signal with the fed back gain estimated value to obtain a limited audio signal. Since the gain estimation circuit will adjust down the gain estimation value when the diaphragm displacement is large and/or the voice coil temperature is high, the resulting gain estimation value will be smaller, so the multiplier will combine the received audio signal with the smaller gain estimation value of the feedback After multiplying the values, the audio signal after clipping can be obtained. The clipping of the audio signal makes the amplitude of the clipping parameter also limited, so the purpose of clipping the diaphragm displacement and/or voice coil temperature can be achieved, and can Reduce the diaphragm displacement and/or voice coil temperature corresponding to the audio signal, prolonging the service life of the speaker. Moreover, the limiting device provided by the present application has better stability and lower time delay, and can improve the performance of the loudspeaker.

For example, taking the first numerical value as 0.1, the second numerical value as 0.1, and the initial estimated gain value as 1 as an example, the limiting device multiplies the audio signal at the first sampling point by the initial estimated gain value 1 to obtain the limited audio Signal 0. The prediction circuit predicts the limit parameter 0 according to the limited audio signal 0, if the limit parameter 0 is high (for example, higher than the first preset threshold), the gain estimation circuit can lower the gain estimate by 0.1, and the adjusted gain The estimated value is 0.9, and the estimated gain value 0.9 is output to the multiplier, and the multiplier multiplies the estimated gain value 0.9 by the audio signal at the second sampling point to obtain the audio signal 1 after limiting. The prediction circuit predicts the limiting parameter 1 according to the limited audio signal 1. If the limiting parameter 1 is high (for example, higher than the first preset threshold), the estimated gain value can be lowered by 0.1, and the adjusted gain estimated The value is 0.8, and the estimated gain value 0.8 is output to the multiplier, and the multiplier multiplies the estimated gain value 0.8 by the audio signal of the third sampling point to obtain the audio signal 2 after limiting. The prediction circuit predicts the limiting parameter 2 according to the limited audio signal 2. If the limiting parameter 2 is low (for example, lower than the second preset threshold), the gain estimation circuit can increase the gain estimation value by 0.1, and the adjusted The estimated gain value of 0.9 is 0.9, and the estimated gain value 0.9 is output to the multiplier, and the multiplier multiplies the estimated gain value 0.9 by the audio signal of the fourth sampling point to obtain the limited audio signal 3, and so on , the audio signal at each sampling point can be clipped.

In the embodiment of the present application, the gain estimation value obtained by the gain estimation circuit is a value greater than 0 and less than or equal to 1. Therefore, after multiplying the audio signal and the gain estimation value, the harmonics caused by the clipping effect can be reduced and the signal-to-noise can be improved. Compare.

Optionally, the sum of the time for the prediction circuit to predict the clipping parameter and the time for the gain estimation circuit to calculate the estimated gain value is less than or equal to the sampling period. The sampling period may be the time length (or duration) between two adjacent sampling points. That is, the time when the gain estimation circuit obtains the estimated gain value minus the time when the audio signal enters the limiting device is less than or equal to the sampling period. Exemplarily, taking the frequency of the audio signal as 48kHz as an example, the sampling period is 1 second divided by 48000, which is about 20 microseconds. Since the sum of the time for predicting the limiting parameter and the time for calculating the estimated gain value is less than or equal to the sampling period, the time delay of the limiting device provided in the embodiment of the present application is relatively small when performing limiting processing on the audio signal.

Exemplarily, the prediction circuit can be set as a straight-through, and the gain estimation circuit can be realized by using the circuit shown in Figure 6 or Figure 7. Since the delay on the wire is negligible, the delay of this gain estimation circuit is relatively small, so the gain The time when the estimated gain value is calculated by the estimation circuit minus the time when the audio signal enters the limiting device is less than or equal to the sampling period.

It can be understood that the limiting device provided in the embodiment of the present application is realized by predicting the limiting parameter according to the audio signal output by the limiting device, obtaining an estimated gain value according to the limiting parameter, and multiplying the audio signal by the estimated gain value fed back. purpose of clipping. In the present application, the gain estimation circuit will lower the gain estimation value when the value of the limiting parameter is higher, and the obtained gain estimation value is smaller, so after multiplying the audio signal and the feedback smaller gain estimation value, it can reach The purpose of limiting is to reduce the displacement of the diaphragm and the temperature of the voice coil corresponding to the limited audio signal, so as to prolong the service life of the speaker. This application adopts the feedback control method to form a closed-loop control system in the limiting device, so the stability is relatively high. Moreover, in the present application, the sum of the time when the prediction circuit predicts the limiting parameter and the time when the gain estimation circuit calculates the estimated gain value is less than or equal to the sampling period, so the time delay is small and the performance of the loudspeaker can be improved.

An embodiment of the present application further provides an audio system, the audio system includes an amplifier, a speaker, and a limiting device as shown in FIG. 2A or 2B or FIG. 3 , and the limiting device is coupled to the speaker through the amplifier.

Optionally, the clipping device provided in the embodiment of the present application may be realized by the hardware circuit shown in FIG. 2A or FIG. 2B or FIG. 3 , or the clipping shown in FIG. 8 may be realized by a processor executing software codes or computer programs. method implementation.

The embodiment of the present application also provides a limiting method, which can be executed by a limiting device. As shown in FIG. 8 , the limiting method includes the following steps S801-S803.

S801. Predict a limiting parameter of the speaker based on the first audio signal.

The first audio signal may be an audio signal output to a speaker. For example, the first audio signal may be an audio signal output by a limiting device, and the audio signal output by the limiting device may be amplified by an amplifier and then output to a speaker. That is, the first audio signal may be an audio signal before being amplified by the amplifier.

The limiting parameter includes at least one of diaphragm displacement or voice coil temperature.

When the limiting parameter includes diaphragm displacement, predicting the limiting parameter of the speaker based on the first audio signal in step S801 includes: predicting the diaphragm displacement of the speaker based on the TS parameter of the speaker and the audio parameter of the first audio signal. The audio parameters of the first audio signal include voltage parameters or current parameters corresponding to the first audio signal.

When the limiting parameter includes voice coil temperature, predicting the limiting parameter of the speaker based on the first audio signal in step S801 includes: predicting the voice coil temperature of the speaker based on the TS parameter of the speaker and the audio parameter of the first audio signal. The audio parameter of the first audio signal includes at least one of a voltage parameter or a current parameter corresponding to the first audio signal.

When the limiting parameters include diaphragm displacement and voice coil temperature, the above step S801 predicts the limiting parameters of the speaker based on the first audio signal, including: based on the TS parameter of the speaker and the voltage parameter or current parameter corresponding to the first audio signal, estimating Diaphragm displacement of the loudspeaker. Estimate the voice coil temperature of the speaker based on the TS parameter of the speaker and the voltage parameter and current parameter corresponding to the first audio signal.

It can be understood that, for a specific implementation manner of predicting the limiting parameter of the loudspeaker based on the first audio signal in step S801 above, reference may be made to the foregoing embodiments, and details are not repeated here.

S802. Obtain an estimated gain value based on the limiting parameter of the loudspeaker.

Exemplarily, step S802 may include: when the limiting parameter of the loudspeaker is higher than a first preset threshold, reducing the estimated gain value of the previous sampling point by a first value to obtain an estimated estimated gain value after adjustment. When the limiting parameter predicted by the predicting circuit is lower than the second preset threshold, the estimated gain value at the previous sampling point is increased by a second value to obtain an estimated estimated gain value after adjustment. The first preset threshold is greater than or equal to the second preset threshold. The first numerical value may be the same as the second numerical value, or may be different from the second numerical value.

Optionally, based on the limiting parameter of the speaker in step S802, the estimated gain value obtained may not be greater than the maximum gain or less than the minimum gain. In this embodiment of the present application, for the first value, the second value, the first preset threshold, Specific values of the second preset threshold, the maximum gain and the minimum gain are not limited. The maximum gain and minimum gain can be preset values.

Optionally, when the limiting parameter includes diaphragm displacement, step S802 may include adjusting the estimated gain value of the previous sampling point downward when the diaphragm displacement is relatively large. When the diaphragm displacement is small, the gain estimate from the previous sampling point can be adjusted upwards. It can be understood that the larger and smaller diaphragm displacements may be compared with one or more preset thresholds. The embodiment of the present application does not limit the specific value of the preset thresholds. In practical applications, it can be determined according to the speaker parameters , environmental parameters, etc. to determine.

Optionally, when the limiting parameter includes the voice coil temperature, step S802 may include adjusting the estimated value of the gain at the previous sampling point downward when the voice coil temperature is high. When the voice coil temperature is low, the gain estimate from the previous sample point can be adjusted upwards. It can be understood that the higher or lower voice coil temperature can also be compared with one or more preset thresholds. The embodiment of the present application does not limit the specific value of the preset thresholds. In practical applications, it can be determined according to Loudspeaker parameters, environment parameters, etc. are determined. The preset threshold for determining whether the temperature of the voice coil is higher or lower and the preset threshold for determining whether the displacement of the diaphragm is larger or smaller may be the same or different.

Optionally, when the limiting parameters include diaphragm displacement and voice coil temperature, step S802 may include according to diaphragm displacement, voice coil temperature, the first weight corresponding to diaphragm displacement, and the second weight corresponding to voice coil temperature, to obtain Gain estimates. It can be understood that the values of the first weight and the second weight are related to parameters such as the degree of influence of diaphragm displacement and voice coil temperature on the life of the speaker in practical applications, and the specific structure of the speaker.

For example, according to the diaphragm displacement predicted in step S801, the estimated value corresponding to the diaphragm displacement at the previous sampling point can be adjusted up or down to obtain the first estimated value, and the voice coil temperature at the previous sampling point can be adjusted up or down according to the voice coil temperature predicted in S801 The corresponding estimated value, to obtain the second estimated value, multiply the first estimated value by the first weight corresponding to the diaphragm displacement, multiply the second estimated value by the second weight corresponding to the voice coil temperature, and multiply the two The results are summed to get the adjusted gain estimate.

The embodiment of the present application does not limit the specific implementation of how to obtain the estimated gain value based on the limiting parameters of the speaker in step S802. The methods of increasing the limiting parameter when it is too low are all within the protection scope of the present application.

S803. Multiply the second audio signal by the estimated gain value to obtain a limited audio signal.

The second audio signal is the input original audio signal. The input initial audio signal may be a downlink audio signal processed by a processing unit (for example, a noise reduction unit), may also be an audio signal collected from a sensor, may also be an audio signal released from multimedia, and the like. The embodiment of the present application does not limit which device the second audio signal is output from.

The first audio signal in step S801 may be an audio signal at the first moment, and the first audio signal may be a limited audio signal. The second audio signal in step S803 is the initial audio signal input at the next sampling point after the first moment, and the second audio signal has not been subjected to limiting processing.

Optionally, the estimated gain value is a value greater than 0 and less than or equal to 1. Therefore, after the second audio signal is multiplied by the estimated gain value, harmonics caused by clipping effects can be reduced and a signal-to-noise ratio can be improved. Moreover, when the displacement of the diaphragm is large and/or the temperature of the voice coil is high, the estimated gain value will be adjusted downward, and the resulting estimated gain value will be smaller. Therefore, after multiplying the second audio signal with the smaller gain estimated value fed back, The purpose of limiting can be achieved, the diaphragm displacement and/or voice coil temperature corresponding to the audio signal can be reduced, and the service life of the speaker can be prolonged. Moreover, the limiting device provided by the present application has better stability and lower time delay, and can improve the performance of the loudspeaker.

Optionally, the sum of the time for the limiting device to predict the limiting parameter and the time for determining the estimated gain value is less than or equal to the sampling period, so when the limiting device limits the second audio signal, the time delay is small.

It can be understood that, in the limiting method provided by the embodiment of the present application, when the value of the limiting parameter is high, the estimated gain value will be lowered, and the estimated gain value obtained is smaller. Therefore, when the second audio signal is combined with a smaller gain After the estimated values are multiplied, the purpose of limiting can be achieved, the diaphragm displacement and voice coil temperature corresponding to the audio signal can be reduced, and the service life of the speaker can be extended. Moreover, in the present application, the sum of the time for predicting the limiting parameter and the time for determining the estimated gain value is less than or equal to the sampling period, so the time delay is small and the performance of the loudspeaker can be improved.

The embodiment of the present application also provides a limiting device, the limiting device includes a processor and an interface circuit, the processor receives or sends a signal through the interface circuit; the processor is used to execute the computer program stored in the memory , so that the clipping device implements the clipping method shown in FIG. 8 .

The embodiment of the present application also provides a computer-readable storage medium, where computer program code is stored in the computer-readable storage medium, and when the computer program code is run on the computer or the processor, the computer or the processing The device implements the clipping method shown in Figure 8.

The embodiment of the present application also provides a computer program product, where the computer program product includes program instructions, and when the program instructions are executed by a computer or a processor, the clipping method shown in FIG. 8 is realized.

The steps of the methods or algorithms described in connection with the disclosure of this application can be implemented in the form of hardware, or can be implemented in the form of a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory (random access memory, RAM), flash memory, erasable programmable read-only memory (erasable programmable ROM, EPROM), electrically erasable Programmable read-only memory (electrically EPROM, EEPROM), registers, hard disk, removable hard disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. Of course, the storage medium may also be a component of the processor. The processor and storage medium can be located in the ASIC. In addition, the ASIC may be located in the core network interface device. Certainly, the processor and the storage medium may also exist in the core network interface device as discrete components.

Those skilled in the art should be aware that, in the above one or more examples, the functions described in the present invention may be implemented by hardware, software, firmware or any combination thereof. When implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, any modification, equivalent replacement, improvement, etc. made on the basis of the technical solution of the present invention shall be included in the protection scope of the present invention.

Claims

A limiting device, characterized in that the limiting device comprises a prediction circuit, a gain estimation circuit and a multiplier, the first input end of the multiplier is used to receive an audio signal, and the output end of the limiting device is passed through The prediction circuit is coupled to the input of the gain estimation circuit, the output of the gain estimation circuit is fed back to the second input of the multiplier, and the output of the limiting device is used for coupling with a loudspeaker;

The predicting circuit is configured to predict a limiting parameter of the loudspeaker based on the audio signal output by the limiting device, and the limiting parameter includes at least one of diaphragm displacement or voice coil temperature;

The gain estimation circuit is configured to obtain an estimated gain value based on the clipping parameter predicted by the prediction circuit;

The multiplier is configured to receive the audio signal and the estimated gain value fed back by the gain estimation circuit, and multiply the audio signal by the estimated gain value to obtain a limited audio signal; the limited The output terminal of the device outputs the limited audio signal.
The limiting device according to claim 1, wherein the limiting device further comprises a saturated limiting circuit, and the output terminal of the multiplier is coupled to the output of the limiting device through the saturated limiting circuit end.
The clipping device according to claim 1 or 2, wherein the prediction circuit comprises a displacement prediction circuit;

The displacement prediction circuit is used to predict the diaphragm displacement of the speaker based on the Thiele-Small parameter of the speaker and the audio signal output by the limiting device; the input parameter of the displacement prediction circuit is the limiter The voltage parameter or current parameter corresponding to the audio signal output by the device.
The limiting device according to any one of claims 1-3, wherein the prediction circuit further comprises a temperature prediction circuit;

The temperature prediction circuit is used to predict the voice coil temperature of the speaker based on the Thiele-Small parameters of the speaker and the audio signal output by the limiting device; the input parameter of the temperature prediction circuit is the limiter At least one of voltage parameters or current parameters corresponding to the audio signal output by the device.
The clipping device according to claim 4, wherein when the prediction circuit includes a displacement prediction circuit and the temperature prediction circuit, the displacement prediction circuit and the temperature prediction circuit are connected in parallel.
The clipping device according to claim 3 or 5, wherein the displacement prediction circuit includes one or more biquad Biquad filters, and the multiple Biquad filters are cascaded.
The limiting device according to claim 4 or 5, wherein the temperature prediction circuit is specifically configured to use the Thiele-Small parameter of the loudspeaker, the voltage parameter corresponding to the audio signal output by the limiting device, and The current parameter identifies the impedance of the loudspeaker and predicts the voice coil temperature of the loudspeaker.
The limiting device according to any one of claims 1-7, wherein the gain estimation circuit is specifically configured to, when the limiting parameter is higher than a first preset threshold, convert the previous sampling point to The estimated gain value of the sampling point is reduced by a first value; when the limiting parameter is lower than a second preset threshold value, the estimated gain value of the previous sampling point is increased by a second value; wherein, the first preset threshold value is greater than or equal to the second preset threshold.
The limiting device according to any one of claims 1-8, wherein the estimated gain value is greater than 0 and less than or equal to 1.
The limiting device according to any one of claims 1-9, characterized in that, the gain estimation circuit comprises a first selector, a subtractor and an adder, and the output terminal of the first selector is the The output terminal of the gain estimation circuit, the output terminal of the first selector is coupled to the first input terminal of the subtractor through the first flip-flop, the second input terminal of the subtractor inputs the first value, and the subtractor The output end of the selector is coupled to the first input end of the first selector; the output end of the first selector is coupled to the first input end of the adder through the second flip-flop, and the first input end of the adder The second input terminal inputs a second value, and the output terminal of the adder is coupled to the second input terminal of the first selector;

The first selector is configured to input the output of the gain estimation circuit to the first flip-flop or the second flip-flop.
The limiting device according to claim 10, wherein the gain estimation circuit further comprises a second selector, a third selector and a fourth selector, the output terminal of the subtractor is connected to the second selector connected to the first input end of the second selector, the second input end of the second selector inputs a preset minimum gain, and the output end of the second selector is connected to the first input end of the first selector; The output end of the adder is connected to the first input end of the third selector, the second input end of the third selector is connected to the output end of the first selector, and the output of the third selector terminal is connected with the first input terminal of the fourth selector, the second input terminal of the fourth selector inputs the preset maximum gain, the output terminal of the fourth selector is connected with the first input terminal of the first selector Two input connections.
The limiting device according to any one of claims 1-11, wherein the sum of the time when the predicting circuit predicts the limiting parameter and the time when the gain estimating circuit calculates the estimated gain value is less than or equal to the sampling period.
A limiting method, characterized in that the limiting method comprises:

Predicting a limiting parameter of the speaker based on the first audio signal, the limiting parameter including at least one of diaphragm displacement or voice coil temperature; the first audio signal is an audio signal output to the speaker;

Obtaining an estimated gain value based on the limiting parameter of the loudspeaker;

multiplying the second audio signal by the estimated gain value to obtain a limited audio signal; the second audio signal is an input initial audio signal.
The limiting method according to claim 13, wherein the prediction of the limiting parameter of the loudspeaker based on the first audio signal comprises:

Predicting the diaphragm displacement of the speaker based on the Thiele-Small parameter of the speaker and the audio parameter of the first audio signal; the audio parameter of the first audio signal includes a voltage parameter or a current parameter corresponding to the first audio signal .
The limiting method according to claim 13 or 14, wherein the prediction of the limiting parameter of the loudspeaker based on the first audio signal further comprises:

Predict the voice coil temperature of the speaker based on the Thiele-Small parameter of the speaker and the audio parameter of the first audio signal; the audio parameter of the first audio signal includes a voltage parameter corresponding to the first audio signal or at least one of the current parameters.
The limiting method according to any one of claims 13-15, wherein said gain estimation value obtained based on the limiting parameter of the loudspeaker comprises:

When the limiting parameter is higher than the first preset threshold, reduce the estimated gain value of the previous sampling point by the first value; The estimated gain value of is increased by a second value; wherein, the first preset threshold is greater than or equal to the second preset threshold.
The limiting method according to claim 16, characterized in that, the estimated gain value is greater than 0 and less than or equal to 1.
The limiting method according to any one of claims 13-17, characterized in that the sum of the time for predicting the limiting parameter and the time for determining the estimated gain value is less than or equal to the sampling period.
A limiting device, characterized in that the limiting device includes a processor and an interface circuit, the processor receives or sends a signal through the interface circuit; the processor is used to execute a computer program stored in a memory, The clipping device is caused to implement the method according to any one of claims 13-18.
A computer-readable storage medium, having computer program codes in the computer-readable storage medium, is characterized in that, when the computer program code runs on a computer or a processor, the computer or the processor executes The method according to any one of claims 13-18.
A computer program product, characterized in that the computer program product includes program instructions, and when the program instructions are executed by a computer or a processor, the method according to any one of claims 13-18 is realized.
An audio system, characterized in that the audio system comprises an amplifier, a loudspeaker, and the limiting device according to any one of claims 1-12, the limiting device is coupled to the loudspeaker through the amplifier .