Over-amplitude suppression device for speaker

Abstract

The present invention addresses the problem of providing an excessive amplitude suppression device for a speaker, which controls the amplitude accuracy of the vibration system of the speaker within a target amplitude range with higher accuracy. [Solution] An amplitude control unit (6) adjusts the gain of a sound source output signal output by a sound source device (5), and outputs the sound source output signal to an amplifier (4) that drives a speaker (2). The amplitude control unit (6) corrects the displacement of the speaker (2) predicted from the sound source output signal on the basis of the equivalent circuit of the speaker (2), using the actual value in the past period of the difference between the predicted displacement of the speaker (2) and the displacement of the vibration system of the speaker (2) detected by the displacement detection unit (7) using the sensor (3). The gain of the sound source output signal is adjusted so that the corrected displacement does not exceed the target displacement amplitude.

Description

Technical Field

[0001] The present invention relates to a technique for suppressing excessive amplitude of a vibration system of a speaker. Background Art

[0002] In a speaker, since the vibration system passively displaces and vibrates according to the size of the input signal, if the input signal is too large, an excessive amplitude is generated, causing the speaker's voice coil frame to bottom out, or the displacement of the elastic body to reach the fracture area and the vibration system components to break, causing the speaker to malfunction.

[0003] In addition, as a technology for suppressing the excessive amplitude of the vibration system of such a speaker, the following technology is known: based on the equivalent circuit of the speaker, a predicted value of the displacement of the vibration system of the speaker corresponding to the input signal is calculated, and when the predicted value is larger than a specified threshold value, the amplitude of the input signal is controlled (for example, patent documents 1 and 2).

[0004] In addition, as a technology related to the present application, there is known a technology for detecting the actual displacement of the vibration system of a speaker by a sensor, or a technology for detecting the input voltage, input current or displacement of the vibration system of the actual speaker and updating the various characteristics of the equivalent circuit of the speaker to characteristics that match the actual speaker based on the detection values ​​(for example, patent document 3).

[0005] Prior art literature:

[0006] Patent Literature:

[0007] Patent Document 1: International Publication No. 2018 / 116861

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2013-55676

[0009] Patent Document 3: Japanese Patent Application Publication No. 2022-143855 Summary of the invention

[0010] Problems to be solved by the invention:

[0011] According to the above-mentioned technology of performing amplitude control by obtaining a predicted value of the displacement of the vibration system of the speaker based on the equivalent circuit of the speaker, it is sometimes impossible to predict the displacement of the speaker with high accuracy due to the degree of reproducibility of the equivalent circuit, deviations among the individual speakers, aging of the characteristics of the individual speakers, etc.

[0012] In addition, it is necessary to perform amplitude control with a margin relative to the target amplitude range, and as a result, the performance of the speaker cannot be fully utilized.

[0013] Therefore, an object of the present invention is to control the amplitude of a vibration system of a speaker with higher accuracy within a target amplitude range.

[0014] Means used to solve the problem:

[0015] In order to achieve the above-mentioned problem, the present invention provides an excessive amplitude suppression device for a speaker, which suppresses the excessive amplitude of the vibration system of the speaker for an input signal, wherein the device comprises: a displacement detection mechanism, which detects the displacement of the vibration system of the speaker; and an amplitude control unit, which takes the input signal as input. Here, the amplitude control unit comprises: a gain adjustment mechanism, which adjusts the input signal with a set gain and outputs it to the speaker; a displacement prediction mechanism, which predicts the displacement of the vibration system of the speaker based on the input signal; a predicted displacement correction mechanism, which corrects the displacement predicted by the displacement prediction mechanism; and a gain setting mechanism, which sets a gain for the gain adjustment mechanism so that the displacement corrected by the predicted displacement correction mechanism is attenuated to a displacement that does not exceed a predetermined displacement amplitude. In addition, the predicted displacement correction mechanism calculates the difference between the displacement predicted by the displacement prediction mechanism in the past and the displacement detected by the displacement detection mechanism corresponding to the input signal used to predict the displacement, and corrects the displacement predicted by the displacement prediction mechanism by an amount corresponding to the calculated difference.

[0016] In addition, in order to achieve the above-mentioned problem, the present invention provides an excessive amplitude suppression device for a speaker, which suppresses the excessive amplitude of the vibration system of the speaker for an input signal, wherein the device comprises: a displacement detection mechanism for detecting the displacement of the vibration system of the speaker; a frequency band division mechanism for dividing the input signal into input signals of each frequency band; an amplitude control unit provided corresponding to each of the frequency bands, and taking the input signal of the corresponding frequency band divided by the frequency band division mechanism as input; and a mixer. Here, each amplitude control unit comprises: a gain adjustment mechanism for adjusting the input signal of the corresponding frequency band with a set gain and outputting it to the mixer; a displacement prediction mechanism for predicting the displacement of the vibration system of the speaker based on the input signal of the corresponding frequency band; a predicted displacement correction mechanism for correcting the displacement predicted by the displacement prediction mechanism; and a gain setting mechanism for setting a gain for the gain adjustment mechanism so that the displacement corrected by the predicted displacement correction mechanism is attenuated to a displacement not exceeding a predetermined displacement amplitude. In addition, the predicted displacement correction mechanism calculates the difference between the displacement predicted by the displacement prediction mechanism in the past and the component of the corresponding frequency band in the displacement detected by the displacement detection mechanism corresponding to the input signal of the corresponding frequency band for predicting the displacement, and corrects the displacement predicted by the displacement prediction mechanism by an amount corresponding to the calculated difference. In addition, the mixer mixes the input signals of the respective frequency bands output from the gain adjustment mechanisms of the respective amplitude control units and outputs the mixed signals to the speaker.

[0017] In addition, in order to achieve the above-mentioned problem, the present invention provides an excessive amplitude suppression device for a speaker, which suppresses the excessive amplitude of the vibration system of the speaker for an input signal, wherein the device comprises: a displacement detection mechanism, which detects the displacement of the vibration system of the speaker; a frequency band division mechanism, which divides the input signal into an input signal on the low frequency side and an input signal on the high frequency side; an amplitude control unit, which takes the input signal on the low frequency side divided by the frequency band division mechanism as input; and a mixer. Here, the amplitude control unit comprises: a gain adjustment mechanism, which adjusts the input signal on the low frequency side with a set gain and outputs it to the mixer; a displacement prediction mechanism, which predicts the displacement of the vibration system of the speaker based on the input signal on the low frequency side; a predicted displacement correction mechanism, which corrects the displacement predicted by the displacement prediction mechanism; and a gain setting mechanism, which sets a gain for the gain adjustment mechanism so that the displacement corrected by the predicted displacement correction mechanism is attenuated to a displacement that does not exceed a predetermined displacement amplitude. In addition, the predicted displacement correction mechanism calculates the difference between the displacement predicted by the displacement prediction mechanism in the past and the low-frequency component of the displacement detected by the displacement detection mechanism corresponding to the low-frequency input signal used to predict the displacement, and corrects the displacement predicted by the displacement prediction mechanism by an amount corresponding to the calculated difference. In addition, the mixer mixes the low-frequency input signal output from the gain adjustment mechanism of the amplitude control unit with the high-frequency input signal divided by the band division mechanism, and outputs the mixed signal to the speaker.

[0018] Here, the above-mentioned excessive amplitude suppression device for a speaker may be configured such that: in the predicted displacement correction means, the displacement predicted by the displacement prediction means is corrected by an amount corresponding to a maximum value of the difference calculated so far.

[0019] In addition, the above-mentioned excessive amplitude suppression device of the speaker can also be constructed as follows: in the gain setting mechanism, when the gain that makes the displacement after correction by the predicted displacement correction mechanism attenuate to a displacement that does not exceed the predetermined displacement amplitude is smaller than the gain currently set by the gain adjustment mechanism, the gain that makes the displacement attenuate to a displacement that does not exceed the displacement amplitude is set for the gain adjustment mechanism.

[0020] In addition, in the above-mentioned excessive amplitude suppression device for the speaker, an input detection mechanism for detecting the input of the speaker and a speaker equivalent circuit updating mechanism can also be provided. In the displacement prediction mechanism, the displacement of the vibration system of the speaker is predicted according to the equivalent circuit of the speaker that is set. In the speaker equivalent circuit updating mechanism, the characteristics of the equivalent circuit set for the displacement prediction mechanism are updated in a manner that matches the relationship between the input of the speaker detected by the input detection mechanism and the displacement detected by the displacement detection mechanism for the input.

[0021] According to the above-mentioned excessive-amplitude suppression device for a loudspeaker, the error of the displacement predicted this time is estimated based on the actual result of the difference between the displacement predicted by the displacement prediction mechanism according to the input signal in the past and the displacement actually detected by the displacement detection mechanism for the input signal, the predicted displacement is corrected by an amount corresponding to the error, and the amplitude is controlled based on the corrected displacement. Therefore, compared with the case where the amplitude is controlled only based on the displacement predicted by the displacement prediction mechanism, the amplitude of the vibration system of the loudspeaker can be controlled within the target amplitude range with higher accuracy.

[0022] In addition, in order to achieve the above-mentioned problem, the present invention provides an excessive amplitude suppression device for a speaker, which suppresses the excessive amplitude of the vibration system of the speaker for an input signal, wherein the device comprises: a displacement detection mechanism for detecting the displacement of the vibration system of the speaker; an input detection mechanism for detecting the input of the speaker; and an amplitude control unit for taking the input signal as input. Here, the amplitude control unit comprises: a gain adjustment mechanism for adjusting the input signal with a set gain and outputting it to the speaker; a displacement prediction mechanism for predicting the displacement of the vibration system of the speaker according to the input signal in accordance with a set equivalent circuit of the speaker; a gain setting mechanism for setting a gain for the gain adjustment mechanism so that the displacement predicted by the displacement prediction mechanism is attenuated to a displacement that does not exceed a predetermined displacement amplitude; and a speaker equivalent circuit updating mechanism for updating the characteristics of the equivalent circuit set for the displacement prediction mechanism in a manner that matches the relationship between the input detected by the input detection mechanism and the displacement detected by the displacement detection mechanism for the input.

[0023] According to such an excessive amplitude suppression device for a speaker, the actual displacement of the vibration system of the speaker detected by the displacement detection mechanism can be used at any time to update the characteristics of the equivalent circuit used by the displacement prediction mechanism when predicting the displacement of the vibration system in a manner that matches the actual characteristics of the speaker. In addition, as a result, compared with a case where the characteristics of the equivalent circuit are updated without using the actual displacement of the vibration system of the speaker, the accuracy of displacement prediction can be improved, and the amplitude of the vibration system of the speaker can be controlled more accurately within the target amplitude range.

[0024] Effect of the invention:

[0025] As described above, according to the present invention, the amplitude of the vibration system of the speaker can be controlled more accurately within the target amplitude range. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a diagram showing the configuration of an acoustic system according to the first embodiment of the present invention.

[0027] Figure 2 It is a diagram showing the configuration of displacement detection according to the first embodiment of the present invention.

[0028] Figure 3 It is a diagram showing the configuration of an attenuator gain control unit according to the first embodiment of the present invention.

[0029] Figure 4 This is a diagram showing an equivalent circuit of the speaker used in the first embodiment of the present invention.

[0030] Figure 5 Detailed Description of the Invention This is a flowchart showing the speaker displacement error calibration process according to the first embodiment of the present invention.

[0031] Figure 6 It is a diagram showing a control example of amplitude control according to the first embodiment of the present invention.

[0032] Figure 7 It is a diagram showing the configuration of an attenuator gain control unit according to the second embodiment of the present invention.

[0033] Figure 8 It is a diagram showing the configuration of an attenuator gain control unit according to a third embodiment of the present invention.

[0034] Fig. 9 It is a diagram showing the configuration of an amplitude control unit according to a fourth embodiment of the present invention.

[0035] Fig.10 It is a diagram showing the configuration of an amplitude control unit according to a fifth embodiment of the present invention.

[0036] Description of reference numerals:

[0037] 1…control unit, 2…speaker, 3…sensor, 4…amplifier, 5…sound source device, 6…amplitude control unit, 7…displacement detection unit, 61…all-pass filter, 62…attenuator, 63…attenuator gain control unit, 201…yoke, 202…magnet, 203…front magnetic plate, 204…voice coil frame, 205…voice coil, 206…basin frame, 207…damper, 208…diaphragm, 209…surrounding ring, 210…dust cover, 211…displacement detection magnet, 220…magnetic circuit, 631…speaker displacement prediction unit, 632…delay , 633…speaker displacement error calibration unit, 634…attenuator gain calculation unit, 635…attenuator gain initial value setting unit, 636…speaker model updating unit, 701…speaker input sensor, 901…sound source output signal frequency band division unit, 902…displacement signal frequency band division unit, 903…frequency band amplitude control unit, 904…mixer, 1001…sound source output signal high frequency / low frequency division unit, 1002…displacement signal low frequency extraction unit, 1003…delay unit, 1004…low frequency amplitude control unit, 1005…mixer. DETAILED DESCRIPTION

[0038] Hereinafter, a first embodiment of the present invention will be described.

[0039] Figure 1 The configuration of the acoustic system according to the first embodiment is shown.

[0040] As shown in the figure, the audio system includes a control unit 1, a speaker 2, a sensor 3 arranged on the speaker 2, an amplifier 4, a sound source device 5 that outputs a sound source output signal S as a sound signal, an amplitude control unit 6, and a displacement detection unit 7 that measures the displacement Xs of the vibration system of the speaker 2 based on the output of the sensor 3.

[0041] In addition, the amplitude control unit 6 adjusts the gain of the sound source output signal as the audio signal output by the sound source device 5 and outputs it to the amplifier 4 as an intermediate output signal. The amplifier 4 amplifies the intermediate output signal with a predetermined gain to generate an amplifier output signal, and drives the speaker 2 using the amplifier output signal.

[0042] In addition, the control unit 1 receives input from the sound source device 5 of information such as the playing state of a song, information on the audio content being played, or information on the output level (volume, etc.).

[0043] Next, the amplitude control unit 6 includes an all-pass filter 61 , an attenuator 62 , and an attenuator gain control unit 63 .

[0044] The all-pass filter 61 outputs an audio signal obtained by delaying the sound source output signal S output by the sound source device 5 by a predetermined delay time to the attenuator 62. The delay time will be described later.

[0045] The attenuator gain control unit 63 calculates and sets the gain of the attenuator 62 based on the displacement Xs of the vibration system of the speaker 2 detected by the displacement detection unit 7 and the sound source output signal S output by the sound source device 5. The attenuator gain control unit 63 will be described in detail later.

[0046] Furthermore, the attenuator 62 adjusts the level of the audio signal output from the all-pass filter 61 with the gain set by the attenuator gain control unit 63 , and outputs the signal to the amplifier 4 as an intermediate output signal.

[0047] Next, Figure 2 a shows the structure of the speaker 2.

[0048] As shown in the figure, the speaker 2 includes a yoke 201 , a magnet 202 , a front magnetic plate 203 , a voice coil bobbin 204 , a voice coil 205 , a basket 206 , a damper 207 , a diaphragm 208 , a surround 209 , a dust cover 210 , and a displacement detection magnet 211 .

[0049] Here, the upper part in the figure is set as the front of the speaker 2, and the lower part is set as the rear of the speaker 2. The yoke 201 has a convex part 2011 protruding forward in the center, and an annular magnet 202 is provided on the outer periphery of the convex part 2011. An annular front magnetic plate 203 is provided on the magnet 202. In addition, the front magnetic plate 203 is composed of a conductive member such as iron. In addition, the magnetic circuit 220 is formed by these yoke 201, magnet 202, and front magnetic plate 203.

[0050] The voice coil bobbin 204 has a hollow cylindrical shape, and a voice coil 205 to which a signal from the amplifier 4 is applied is wound around the outer circumference. In addition, the convex portion 2011 of the yoke 201 is inserted into the hollow portion of the voice coil bobbin 204 from the rear so that the voice coil bobbin 204 can move forward and backward relative to the yoke 201, and the voice coil 205 is arranged between the convex portion 2011 of the yoke 201 and the front magnetic plate 203, where the magnetic flux generated by the magnetic circuit 220 between the inner circumferential ends of the front magnetic plate 203 passes.

[0051] The diaphragm 208 has a shape similar to the side of a truncated cone with the front-rear direction of the speaker 2 as the height direction, and its outer peripheral end is connected to the front end of the basket 206 at the edge 209. In addition, the inner peripheral end of the diaphragm 208 is fixed to the front end of the voice coil bobbin 204.

[0052] In the structure of the speaker 2 as described above, when the output signal from the amplifier 4 is applied to the voice coil 205, the voice coil bobbin 204 vibrates back and forth in accordance with the amplitude of the output signal due to the electromagnetic action between the magnetic flux generated from the magnetic circuit 220 and the signal flowing in the voice coil 205. In addition, when the voice coil bobbin 204 vibrates, the diaphragm 208 connected to the voice coil bobbin 204 vibrates, and a sound corresponding to the signal from the amplifier 4 is generated.

[0053] The displacement detection magnet 211 is fixed to the outer peripheral side of the voice coil bobbin 204 so as to move up and down together with the voice coil bobbin 204 , and generates a magnetic flux in a direction orthogonal to the magnetic flux generated by the magnetic circuit 220 .

[0054] Here, the sensor 3 is fixed to a position of the non-vibration system of the speaker 2 such as the front magnetic plate 203, close to the displacement detection magnet. The sensor 3 is a magnetic angle sensor such as Figure 2 As shown in FIG. 2 , the inverse tangent Qs / Qc of the angle between the magnetic flux vector Qc acting from the magnetic circuit 220 and the magnetic flux vector Qs acting from the displacement detection magnet 211 is detected and output as a magnetic angle. Since the magnetic flux vector generated by the displacement detection magnet acting on the sensor 3 changes according to the displacement of the displacement detection magnet 211 accompanying the displacement of the voice coil former 204, the magnetic angle becomes a value that follows the displacement amount of the voice coil former 204.

[0055] In addition, if Figure 1 As shown, the displacement detection unit 7 measures the displacement of the vibration system of the speaker 2 based on the output of the sensor 3, and outputs it to the attenuator gain control unit 63 as the displacement Xs.

[0056] Next, Figure 3 The configuration of the attenuator gain control section 63 of the amplitude control section 6 is shown.

[0057] As shown in the figure, the attenuator gain control section 63 includes a speaker displacement prediction section 631 , a delay device 632 , a speaker displacement error calibration section 633 , an attenuator gain calculation section 634 , and an attenuator gain initial value setting section 635 .

[0058] The speaker displacement prediction unit 631 predicts the displacement of the vibration system of the speaker 2 caused by the sound source output signal S(n) output by the sound source device 5 according to the preset equivalent circuit (speaker model) of the speaker 2, and outputs it as the predicted displacement Xp(n).

[0059] Here, as an equivalent circuit of the speaker 2, for example, Figure 4 The equivalent circuit is shown.

[0060] In addition, when using Figure 4In the case of the equivalent circuit shown in FIG. 1 , the predicted displacement Xp(n) can be obtained by the following equation (1).

[0061] Formula (1):

[0062] Xp(n)=-a1Xp(n-1)-a2Xp(n-2)-a3Xp(n-3)+{b0S(n)+b1S(n-1)

[0063] +b2S(n-2)+b3S(n-3)}A

[0064] a0=R e K ms +2F s (R e R ms +L e K ms +Bl 2 )+4F s 2 (R e M ms +L e R ms )+8F s 3 (M ms L e )

[0065] a1={3R e K ms +2F s (R e R ms +L e K ms +Bl 2 )4F s 2 (R e M ms +L e R ms )24F s 3 (M ms L e )} / a0

[0066] a2={3R e K ms 2F s (R e R ms +L e K ms +Bl 2 )4F s 2 (R e M ms +Le R ms )+24F s 3 (M ms L e )} / a0

[0067] a3={R e K ms 2F s (R e R ms +L e K ms +Bl 2 )+4F s 2 (R e M ms +L e R ms )8F s 3 (M ms L e )} / a0

[0068] b0=Bl / a0

[0069] b1=3Bl / a0

[0070] b2=3Bl / a0

[0071] b3=Bl / a0

[0072] Here, A is the gain of the amplifier 4, Xp is the time series data, and Xp(i) represents the i-th data of the predicted displacement Xp. In addition, S is the time series data, and S(i) represents the i-th data of the sound source output signal S. In addition, F s is the sampling frequency of these time series data.

[0073] Here, as the value of the gain A of the amplifier 4 , if the value is known from a set value or a design value, the value is used.

[0074] In addition, when the value of the gain A of the amplifier 4 is not known, the gain A can be obtained, for example, as follows.

[0075] That is, right after the audio system is started, a test signal with a frequency close to the inaudible range (e.g., 20 Hz) within the range of displacement that the sensor 3 can detect is output from the sound source device 5 as the sound source output signal S(n), and the displacement Xs detected by the displacement detection unit 7 is used to solve the following equation (2), thereby determining the gain A.

[0076] Formula (2):

[0077] Xs(n)=-a1Xs(n-1)-a2Xs(n-2)-a3Xs(n-3)+{b0S(n)+b1S(n-1)

[0078] +b2S(n-2)+b3S(n-3)}A

[0079] Among them, Xs is the time series data, and Xs(i) represents the i-th data of displacement Xs.

[0080] Here, the speaker displacement prediction unit 631 may also use Figure 4 The circuit shown is different from the equivalent circuit and calculates the predicted displacement Xp(n).

[0081] Alternatively, the correspondence between the sound source output signal S and the displacement Xp may be set in advance in the speaker displacement prediction unit 631 , and the predicted displacement Xp(n) may be calculated according to the correspondence set in the speaker displacement prediction unit 631 .

[0082] return Figure 3 The predicted displacement Xp(n) calculated by the speaker displacement prediction unit 631 is output to the speaker displacement error calibration unit 633 and the delay unit 632 .

[0083] The delay device 632 delays the input predicted displacement Xp(n) by Td and outputs it as delayed predicted displacement Xp(n-Td) to the speaker displacement error calibration unit 633. Here, Td corresponds to the delay until the displacement Xs corresponding to the predicted displacement Xp(n) is detected by the displacement detection unit 7.

[0084] The speaker displacement error calibration unit 633 uses the predicted displacement Xp(n) input from the speaker displacement prediction unit 631, the delayed predicted displacement Xp(n-Td) input from the delay device 632, and the displacement Xs(n) input from the displacement detection unit 7 to perform speaker displacement error calibration processing, correct the error of the predicted displacement Xp(n) and output it as the calibrated predicted displacement X(n) to the attenuator gain calculation unit 634.

[0085] Figure 5 2 shows a procedure of the speaker displacement error calibration process performed by the speaker displacement error calibration unit 633. Here, the speaker displacement error calibration process is repeatedly performed continuously or intermittently.

[0086] As shown in the figure, in this process, first, the prediction error ΔX(n) is calculated by Xs(n)-Xp(n-Td) (step 502).

[0087] Then, it is checked whether the prediction error ΔX(n) is 0 (step 504). If it is 0, the prediction displacement Xp(n) is output as is to the attenuator gain calculation unit 634 as the calibrated prediction displacement X(n) (step 506), and the speaker displacement error calibration process is ended.

[0088] On the other hand, when it is determined in step 504 that the prediction error ΔX(n) is not 0, it is investigated whether the prediction error ΔX(n) is greater than 0 (step 508). If it is greater than 0, it is further investigated whether Xp(n) is less than 0 (step 510). When it is less than 0, the predicted displacement Xp(n) is output as it is to the attenuator gain calculation unit 634 as the calibrated predicted displacement X(n) (step 506), and the speaker displacement error calibration process is terminated.

[0089] On the other hand, when it is determined in step 510 that Xp(n) is not less than 0, a function that outputs a when the absolute value of a is greater than the absolute value of b and outputs b in other cases is set to absMAX(a, b), and ΔmaxX(n) is calculated by ΔmaxX(n)=absMAX{ΔX(n), ΔPXR} (step 512). Therefore, if the absolute value of ΔX(n) is greater than the absolute value of ΔPXR, ΔmaxX(n)=ΔX(n), and if the absolute value of ΔX(n) is less than the absolute value of ΔPXR, ΔmaxX(n)=ΔPXR.

[0090] In addition, the initial value of ΔPXR is set to zero.

[0091] Then, ΔPXR is updated to ΔmaxX(n) (step 514 ).

[0092] In addition, the calibrated predicted displacement X(n) is calculated by X(n)=Xp(n)+ΔPXR and output to the attenuator gain calculation unit 634 (step 516), thereby terminating the speaker displacement error calibration process.

[0093] On the other hand, when it is determined in step 508 that the prediction error ΔX(n) is not greater than 0, that is, when the prediction error ΔX(n) is less than 0, it is further investigated whether Xp(n) is greater than 0 (step 518). When it is greater than 0, the predicted displacement Xp(n) is output as it is to the attenuator gain calculation unit 634 as the calibrated predicted displacement X(n) (step 506), and the speaker displacement error calibration process is terminated.

[0094] On the other hand, when it is determined in step 518 that Xp(n) is not greater than 0, ΔmaxX(n) is obtained by ΔmaxX(n)=absMAX{ΔX(n), ΔNXR} (step 520).

[0095] In addition, the initial value of ΔNXR is set to zero.

[0096] Then, ΔNXR is updated to ΔmaxX(n) (step 522 ).

[0097] In addition, the calibrated predicted displacement X(n) is calculated by X(n)=Xp(n)+ΔNXR and output to the attenuator gain calculation unit 634 (step 524), thereby terminating the speaker displacement error calibration process.

[0098] The above is a description of the speaker displacement error calibration process performed by the speaker displacement error calibration unit 633 .

[0099] Here, ΔPXR and ΔNXR set in step 514 and step 522 of the above speaker displacement error calibration process represent the values ​​at which the absolute values ​​of the positive and negative errors of the predicted displacement Xp with respect to the displacement Xs become the maximum in the period up to that point.

[0100] Therefore, the calibrated predicted displacement X(n) calculated in steps 516 and 524 is a value obtained by correcting the predicted displacement Xp(n) by an amount corresponding to the maximum error in the past.

[0101] In addition, when the prediction error ΔX(n) is larger than 0 and Xp(n) is smaller than 0 (steps 508, 510), or when the prediction error ΔX(n) is smaller than 0 and Xp(n) is larger than 0 (steps 508, 518), ΔPXR / ΔNXR is not updated or the predicted displacement Xp(n) is corrected using ΔPXR / ΔNXR. This is because, in this case, even if ΔPXR / ΔNXR is used for correction, the absolute value of the calibrated predicted displacement X(n) is smaller than the absolute value of the predicted displacement X(n) or the prediction error ΔX(n), and therefore it is inappropriate to consider the prediction error ΔX(n) when correcting the predicted displacement X(n) in order to suppress excessive amplitude.

[0102] In addition, in the above speaker displacement error calibration process, when it is determined in step 504 that the predicted error ΔX(n) is 0, the following processing can be performed instead of step 506: the one with the larger absolute value between X(n)=Xp(n)+ΔPXR and X(n)=Xp(n)+ΔNXR is calculated as the predicted displacement X(n) after calibration, and output it to the attenuator gain calculation unit 634.

[0103] return Figure 3 The attenuator gain initial value setting unit 635 sets the initial value of the attenuator gain (eg, 0 dB) to the attenuator gain calculation unit 634 in accordance with the control of the control unit 1 .

[0104] Here, the control unit 1 causes the attenuator gain initial value setting unit 635 to set the initial value of the attenuator gain when the audio system is initialized, when the audio system is started, when the output level (volume) of the sound source device 5 is reduced, when the content being played by the sound source device 5 changes, etc.

[0105] Next, the attenuator gain calculation unit 634 calculates the attenuator gain G, and if the attenuator gain G changes, sets the changed attenuator gain G to the attenuator 62 as the gain of the attenuator 62 .

[0106] Here, as described above, the attenuator 62 adjusts the level of the audio signal output from the all-pass filter 61 at the gain set by the attenuator gain control, and outputs the signal to the amplifier 4 as an intermediate output signal.

[0107] The attenuator gain G of the attenuator gain calculation section 634 is calculated as follows.

[0108] That is, the attenuator gain calculation unit 634 is preset with a target displacement TrgX. The target displacement TrgX is the maximum absolute value of the displacement allowed for the vibration system of the speaker 2. For example, when the displacement between +1.0 mm and -1.0 mm is allowed for the vibration system of the speaker 2, 1.0 mm is set as the target displacement TrgX.

[0109] Furthermore, when the attenuator gain initial value is set by the attenuator gain initial value setting unit 635 , the attenuator gain calculation unit 634 sets the attenuator gain G to the set initial value.

[0110] In addition, the calibrated predicted displacement X(n) output from the speaker displacement error calibration unit 633 is then compared with the target displacement TrgX. If the absolute value of the calibrated predicted displacement X(n) is larger than the target displacement TrgX, the ratio of the absolute value of the target displacement TrgX to the calibrated predicted displacement X(n) is calculated, i.e., TrgX / |X(n)|.

[0111] Furthermore, if the gain represented by TrgX / |X(n)| is smaller than the current attenuator gain G (if it is a gain that increases the attenuation amount), the attenuator gain G is updated to the gain represented by TrgX / |X(n)|.

[0112] In the calibration of the attenuator gain control unit 63, the above Figure 1The delay time of the all-pass filter 61 is the delay time from the output of the predicted displacement Xp(n) by the speaker displacement prediction unit 631 until the attenuator gain G is updated in the attenuator gain calculation unit 634 in response to the calibrated predicted displacement X(n) output from the speaker displacement error calibration unit 633 and then set to the attenuator 62. In this delay time, the time required for calculating the predicted displacement Xp(n) in the speaker displacement prediction unit 631 is dominant.

[0113] So, here Figure 6 An example of a simulation effect of the amplitude control by the amplitude control unit 6 as described above is shown.

[0114] The example shown in the figure is an example in which the target displacement TrgX is set to 1.0 mm. When the sound source output signal S output by the sound source device 5 is output as is to the amplifier 4 without amplitude control, the vibration system of the speaker 2 vibrates between +2.5 mm and -2.5 m as shown by line A. When the amplitude control of the first embodiment is performed on the same sound source output signal S, as shown by line B, the displacement range of the vibration system of the speaker 2 can be made between +1.0 mm and -1.0 m.

[0115] The delay of the vibration when the amplitude control is performed (line B) relative to the vibration when the amplitude control is not performed (line A) is caused by the delay of the all-pass filter 61 .

[0116] The first embodiment of the present invention has been described above.

[0117] Here, the speaker displacement error calibration process in the first embodiment may be repeated continuously or intermittently throughout the entire period of operation of the audio system, but may also be repeated only during a specified period such as when the audio system is initialized, when the audio system is started, when the output level (volume) of the sound source device 5 changes, or during intervals between playback of content by the sound source device 5 (for example, between songs when the content is music).

[0118] In the case where the speaker displacement error calibration process is performed only during a predetermined period, after the period has elapsed, the speaker displacement error calibration unit 633 performs the error-fixed speaker displacement error calibration process. Figure 5 Steps 512, 514, 520, and 522 of the speaker displacement error calibration process are skipped, and the ΔPXR and ΔNXR used in steps 516 and 524 are fixed to the ΔPXR and ΔNXR finally obtained by the speaker displacement error calibration process performed in the prescribed period.

[0119] As described above, according to the first embodiment, the error of the displacement predicted this time is estimated based on the actual result of the difference between the displacement predicted by the speaker displacement prediction unit 631 according to the sound source output signal S in the past and the displacement actually detected by the displacement detection unit 7 for the sound source output signal S, the predicted displacement is corrected by an amount corresponding to the error, and the amplitude is controlled based on the corrected displacement. Therefore, compared with the case where the amplitude is controlled only based on the displacement predicted by the speaker displacement prediction unit 631, the amplitude of the vibration system of the speaker 2 can be controlled with higher accuracy within the target amplitude range.

[0120] Hereinafter, a second embodiment of the present invention will be described.

[0121] This second embodiment is as follows Figure 7 As shown, the difference from the first embodiment is that a speaker input sensor 701 for detecting the current flowing in the speaker 2 or the input voltage of the speaker 2 is provided, and the attenuator gain control unit 63 is set to Figure 7 The composition shown.

[0122] like Figure 7 As shown, regarding the attenuator gain control unit 63 of the second embodiment, Figure 3 The attenuator gain control unit 63 of the first embodiment shown is provided with a speaker model updating unit 636 that updates the characteristics of the equivalent circuit used by the speaker displacement prediction unit 631 when predicting the displacement of the vibration system.

[0123] When the audio system is initialized, when the audio system is started, when the output level (volume) of the sound source device 5 changes, or when the sound source device 5 pauses in playing content (for example, between songs when the content is music), the control unit 1 controls the all-pass filter or attenuator 62 of the amplitude control unit 6 to output the input signal in a straight-through manner, so that the sound source device 5 outputs an appropriate output signal such as a test signal, a music signal, or an audio watermark signal as the sound source output signal, and causes the speaker model updating unit 636 to update the equivalent circuit.

[0124] During the updating operation, the speaker model updating unit 636 obtains the characteristics of the equivalent circuit that matches the behavior of the speaker 2 based on the measured values ​​of the current flowing in the speaker 2 or the input voltage of the speaker 2 detected by the speaker input sensor 701, or the displacement Xs detected by the displacement detection unit 7, and updates the characteristics of the equivalent circuit used by the speaker displacement prediction unit 631 when predicting the displacement of the vibration system to the obtained characteristics.

[0125] For example, if the characteristic of the equivalent circuit is Figure 4 The equivalent circuit of the speaker 2 shown is K ms(x); Stiffness, the speaker model updating unit 636 can calculate based on the measured value as follows.

[0126] That is, the resonance frequency fs of the speaker 2 at the impedance Z = u / i is detected based on the current i flowing through the speaker 2 and the input voltage u of the speaker 2. Then, using M ms ; Mechanical mass, calculation

[0127] K ms (x) = (2πfs) 2 M ms

[0128] Calculate the displacement Xs and K of the vibration system of the speaker 2 output by the sensor 3 ms (Xs), and calculate the nonlinear K according to the obtained relationship ms Characteristics of (Xs).

[0129] Here, you can also prepare K in advance ms (Xs) is calculated to match the displacement x and K ms The pattern of the relationship between (Xs) is K ms (Xs) nonlinear characteristics, thus calculating K ms (Xs) has nonlinear characteristics.

[0130] According to such an audio system, the actual displacement of the vibration system of the speaker 2 detected by the displacement detection unit 7 can be used at any time to update the characteristics of the equivalent circuit used by the speaker displacement prediction unit 631 when predicting the displacement of the vibration system in a manner that well matches the actual characteristics of the speaker 2.

[0131] Hereinafter, a third embodiment of the present invention will be described.

[0132] The third embodiment differs from the second embodiment only in the configuration of the attenuator gain control unit 63 .

[0133] Figure 8 The configuration of the attenuator gain control unit 63 according to the third embodiment is shown.

[0134] As shown in the figure, the attenuator gain control unit 63 of the third embodiment is Figure 7 In the attenuator gain control section 63 of the second embodiment shown, the delay device 632 and the speaker displacement error calibration section 633 are deleted, and the predicted displacement Xp(n) calculated by the speaker displacement prediction section 631 is output to the attenuator gain calculation section 634 .

[0135] In the third embodiment, the attenuator gain calculation unit 634 calculates the attenuator gain G described in the first embodiment by using the predicted displacement Xp(n) instead of the calibrated predicted displacement X(n).

[0136] According to such an acoustic system, the actual displacement of the vibration system of the speaker 2 detected by the displacement detection unit 7 can be used at any time to update the characteristics of the equivalent circuit used by the speaker displacement prediction unit 631 when predicting the displacement of the vibration system in a manner that matches the actual characteristics of the speaker 2. In addition, as a result, compared with the case where the characteristics of the equivalent circuit are not updated using the actual displacement of the vibration system of the speaker 2, the accuracy of the displacement prediction can be improved, and the amplitude of the vibration system of the speaker 2 can be controlled more accurately within the target amplitude range.

[0137] Hereinafter, a fourth embodiment of the present invention will be described.

[0138] The fourth embodiment of the present invention is different from the first embodiment in the configuration of the amplitude control unit 6 .

[0139] Fig. 9 The configuration of the amplitude control unit 6 according to the fourth embodiment is shown.

[0140] As shown in the figure, the amplitude control unit 6 of the fourth embodiment includes a sound source output signal band dividing unit 901 , a displacement signal band dividing unit 902 , a plurality of amplitude control units for each frequency band 903 , and a mixer 904 .

[0141] All the frequency band amplitude control units 903 have the same configuration as the amplitude control unit 6 in any one of the first embodiment, the second embodiment, and the third embodiment, and perform the same processing.

[0142] Each frequency band amplitude control unit 903 is set to correspond to each frequency band of the multiple frequency bands obtained by dividing the entire frequency band of the sound source output signal S. The sound source output signal band dividing unit 901 divides the sound source output signal S output by the sound source device 5 into frequency bands, and outputs the sound source output signal S of each frequency band to the frequency band amplitude control unit 903 corresponding to the frequency band. The displacement signal band dividing unit 902 divides the displacement signal Xs output by the displacement detection unit 7 into frequency bands, and outputs the displacement signal Xs of each frequency band to the frequency band amplitude control unit 903 corresponding to the frequency band.

[0143] The signals output by the frequency-band amplitude control units 903 after performing the above-described processing on the sound source output signal S and the displacement signal Xs of the corresponding frequency band are input to the mixer 904 .

[0144] The mixer 904 combines the signals input from the respective frequency band amplitude control units 903 and outputs the combined signals to the amplifier 4 as an intermediate output signal.

[0145] By Fig. 9 The amplitude control unit 6 shown performs amplitude control for each frequency band, thereby suppressing excessive vibration and suppressing a decrease in the speaker output level as a whole.

[0146] Hereinafter, a fifth embodiment of the present invention will be described.

[0147] The fifth embodiment of the present invention is different from the first embodiment in the configuration of the amplitude control unit 6 .

[0148] Fig.10 The configuration of the amplitude control unit 6 according to the fifth embodiment is shown.

[0149] As shown in the figure, the amplitude control unit 6 of the fifth embodiment includes a sound source output signal high-frequency / low-frequency division unit 1001 , a displacement signal low-frequency extraction unit 1002 , a delay unit 1003 , a low-frequency amplitude control unit 1004 , and a mixer 1005 .

[0150] The sound source output signal high-frequency / low-frequency dividing unit 1001 divides the sound source output signal S output by the sound source device 5 into a high-frequency component and a low-frequency component, outputs the high-frequency component to the delay unit 1003 , and outputs the low-frequency component to the low-frequency amplitude control unit 1004 .

[0151] The displacement signal low-frequency extraction unit 1002 extracts the low-frequency component of the displacement signal Xs outputted from the displacement detection unit 7 , and outputs the extracted low-frequency component to the low-frequency amplitude control unit 1004 .

[0152] The low-frequency amplitude control unit 1004 has the same configuration as the amplitude control unit 6 in any one of the first embodiment, the second embodiment, and the third embodiment, and performs the same processing.

[0153] In addition, the low-frequency amplitude control unit 1004 outputs the obtained signal by performing the above-mentioned processing on the low-frequency sound source output signal S and the displacement signal Xs to the mixer 904 .

[0154] The delay unit 1003 delays the signal of the high frequency component of the input sound source output signal S by an amount corresponding to the delay in the processing in the low frequency amplitude control unit 1004 , and outputs the signal to the mixer 904 .

[0155] The mixer 904 combines the signals input from the delay unit 1003 and the low-frequency amplitude control unit 1004 , and outputs the synthesized signal to the amplifier 4 as an intermediate output signal.

[0156] The larger displacement of the vibration system of the speaker 2 is mainly caused by the low-frequency component, so Fig.10The amplitude control section 6 shown performs amplitude control only on the low-frequency side, and can effectively suppress excessive vibration and minimize a decrease in the speaker output level as a whole.

[0157] In addition, as such a configuration for performing amplitude control only on the low frequency side, it is also possible to use a reserved Fig. 9 The amplitude control device shown in the figure has a configuration in which a plurality of amplitude control units 903 for each frequency band corresponding to a plurality of frequency bands on the low frequency side are replaced with a delay unit 1003 for each frequency band amplitude control unit 903 corresponding to a plurality of frequency bands on the high frequency side.

[0158] The embodiments of the present invention have been described above.

Claims

1. A device for suppressing excessive amplitude of a loudspeaker, which suppresses excessive amplitude of a vibration system of a loudspeaker for an input signal, characterized in that: have: a displacement detection mechanism for detecting the displacement of the vibration system of the speaker; and an amplitude control unit, taking the input signal as input, The amplitude control unit comprises: A gain adjustment mechanism, which adjusts the input signal with a set gain and outputs the signal to the speaker; A displacement prediction mechanism, which predicts the displacement of the vibration system of the speaker according to the input signal; a predicted displacement correction mechanism for correcting the displacement predicted by the displacement prediction mechanism; and a gain setting means for setting a gain for the gain adjustment means so that the displacement corrected by the predicted displacement correction means is attenuated to a displacement not exceeding a predetermined displacement amplitude; The predicted displacement correction means calculates a difference between a displacement predicted by the displacement prediction means in the past and a displacement detected by the displacement detection means corresponding to the input signal used to predict the displacement, and corrects the displacement predicted by the displacement prediction means by an amount corresponding to the calculated difference.

2. A device for suppressing excessive amplitude of a loudspeaker, which suppresses excessive amplitude of a vibration system of a loudspeaker in response to an input signal, characterized in that: have: A displacement detection mechanism for detecting the displacement of the vibration system of the speaker; A frequency band splitting mechanism, which splits the input signal into input signals of each frequency band; an amplitude control unit provided corresponding to each of the frequency bands and taking as input an input signal of the corresponding frequency band divided by the frequency band dividing means; as well as mixer, Each of the amplitude control units comprises: A gain adjustment mechanism adjusts the input signal of the corresponding frequency band with a set gain and outputs it to the mixer; A displacement prediction mechanism, which predicts the displacement of the vibration system of the loudspeaker according to the input signal of the corresponding frequency band; A predicted displacement correction mechanism, which corrects the displacement predicted by the displacement prediction mechanism; as well as a gain setting means for setting a gain for the gain adjustment means so that the displacement corrected by the predicted displacement correction means is attenuated to a displacement not exceeding a predetermined displacement amplitude; The predicted displacement correction mechanism calculates a difference between a displacement predicted by the displacement prediction mechanism in the past and a component of a corresponding frequency band in the displacement detected by the displacement detection mechanism corresponding to an input signal of the corresponding frequency band for predicting the displacement, and corrects the displacement predicted by the displacement prediction mechanism by an amount corresponding to the calculated difference. The mixer mixes input signals of the respective frequency bands output from the gain adjustment mechanisms of the amplitude control units, and outputs the mixed signals to the speaker.

3. A device for suppressing excessive amplitude of a loudspeaker, which suppresses excessive amplitude of a vibration system of a loudspeaker in response to an input signal, characterized in that: have: A displacement detection mechanism for detecting the displacement of the vibration system of the speaker; A frequency band splitting mechanism, which splits the input signal into a low-frequency input signal and a high-frequency input signal; an amplitude control unit which receives as input the input signal on the low frequency side divided by the frequency band dividing means; as well as mixer, The amplitude control unit comprises: A gain adjustment mechanism, which adjusts the input signal on the low-frequency side with a set gain and outputs the signal to the mixer; A displacement prediction mechanism, which predicts the displacement of the vibration system of the loudspeaker according to the input signal on the low-frequency side; a predicted displacement correction mechanism for correcting the displacement predicted by the displacement prediction mechanism; and a gain setting means for setting a gain for the gain adjustment means so that the displacement corrected by the predicted displacement correction means is attenuated to a displacement not exceeding a predetermined displacement amplitude; The predicted displacement correction mechanism calculates a difference between a displacement predicted by the displacement prediction mechanism in the past and a low-frequency component of the displacement detected by the displacement detection mechanism corresponding to the low-frequency input signal used to predict the displacement, and corrects the displacement predicted by the displacement prediction mechanism by an amount corresponding to the calculated difference. The mixer mixes the low-frequency input signal output from the gain adjustment mechanism of the amplitude control unit and the high-frequency input signal divided by the band division mechanism, and outputs the mixed signals to the speaker.

4. The excessive amplitude suppression device for a loudspeaker according to any one of claims 1 to 3, characterized in that: The predicted displacement correction means corrects the displacement predicted by the displacement prediction means by an amount corresponding to a maximum value of the difference calculated so far.

5. The excessive amplitude suppression device for a loudspeaker according to any one of claims 1 to 3, characterized in that: When the gain that causes the displacement after correction by the predicted displacement correction mechanism to attenuate to a displacement that does not exceed a predetermined displacement amplitude is smaller than the gain currently set to the gain adjustment mechanism, the gain setting mechanism sets the gain that causes the displacement to attenuate to a displacement that does not exceed the displacement amplitude for the gain adjustment mechanism.

6. The excessive amplitude suppression device for a speaker according to any one of claims 1 to 3, characterized in that: have: An input detection mechanism for detecting an input of the speaker; as well as Loudspeaker equivalent circuit update mechanism, The displacement prediction mechanism predicts the displacement of the vibration system of the speaker according to the set equivalent circuit of the speaker. The speaker equivalent circuit updating means updates the characteristics of the equivalent circuit set by the displacement prediction means so as to match the relationship between the input of the speaker detected by the input detection means and the displacement detected by the displacement detection means in response to the input.

7. A device for suppressing excessive amplitude of a loudspeaker, which suppresses excessive amplitude of a vibration system of a loudspeaker in response to an input signal, characterized in that: have: A displacement detection mechanism for detecting the displacement of the vibration system of the speaker; An input detection mechanism for detecting an input of the speaker; and an amplitude control unit, taking the input signal as input, The amplitude control unit comprises: A gain adjustment mechanism, which adjusts the input signal with a set gain and outputs the signal to the speaker; A displacement prediction mechanism predicts the displacement of the vibration system of the speaker according to the input signal in accordance with the set equivalent circuit of the speaker; a gain setting mechanism for setting a gain for the gain adjustment mechanism so that the displacement predicted by the displacement prediction mechanism is attenuated to a displacement that does not exceed a predetermined displacement amplitude; as well as The speaker equivalent circuit updating means updates the characteristics of the equivalent circuit set by the displacement prediction means so as to match the relationship between the input of the speaker detected by the input detection means and the displacement detected by the displacement detection means in response to the input.

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