Thermal protection of a system having a driver for driving

Abstract

An audio system may include a plurality of transducers, a temperature estimator, and a thermal control subsystem. The temperature estimator may be configured to monitor a physical quantity associated with a plurality of transducers and determine an estimated temperature associated with a first transducer of the plurality of transducers based on the physical quantity. The thermal control subsystem may be configured to generate an output signal based on the input signal, the output signal for driving the plurality of transducers; and controlling the output signal based on the estimated temperature.

Description

Technical Field

[0001] This disclosure generally relates to estimating parameters of electromagnetic loads (e.g., tactile transducers). Background Technology

[0002] Modern electronic devices, including smartphones, tablets, computers, and other devices, typically include one or more transducers (e.g., one or more speakers and / or one or more haptic transducers) that can generate audio and / or haptic effects for the user of the device.

[0003] When such transducers are pushed to their limits, they can be damaged. A common failure mode for overdriven transducers (e.g., loudspeakers / haptic transducers) is thermal damage. As an example, for a loudspeaker, if the voice coil exceeds its maximum temperature, the glue holding the voice coil together and attaching it to the diaphragm may melt, causing irreparable damage. As another example, at higher temperatures, the magnets in a haptic transducer may demagnetize and / or the coil of the haptic transducer may melt, causing an electrical short circuit. Loudspeaker protection algorithms are typically used to drive loudspeakers to their maximum volume while ensuring that the loudspeaker does not exceed its rated limits, and similar protection algorithms can be used in conjunction with haptic transducers.

[0004] In traditional configurations, a single amplifier typically drives a single transducer. To determine the thermal state of the transducer, a pilot tone, typically low-frequency (e.g., 12 Hz or 48 Hz), can be injected into the system's playback signal. This pilot tone is usually injected in the digital domain of the playback path, upstream of any digital-to-analog converters and amplifiers in the playback path. The processing system can then monitor voltage and current feedback from the transducer (e.g., via an analog-to-digital converter) and calculate the resistance of the transducer coil from this monitored voltage and current feedback. The calculated resistance Re can then be directly mapped to the coil temperature using the following linear relationship:

[0005]

[0006] Where T is the temperature of the coil, α is the temperature coefficient of the coil (e.g., the nominal value for copper is 0.00393 Ω / °C), and Re... measured It is the calculated value of the resistance, while Re cal At ambient temperature T amb Calibration value of the lower resistor 。

[0007] However, more modern transducer systems may include multiple transducers driven by a single amplifier. For example, a modern transducer system may include a single amplifier driving a dual-tone transducer comprising a woofer (for reproducing audio at lower audible frequencies) and a tweeter (for reproducing audio at higher audio frequencies) connected in parallel. The impedance measured using a single pair of feedback voltage and current signals, obtained through conventional methods of monitoring the voltage and current supplied to the amplifier, is the parallel impedance of the two transducers (including the impedance of any electrical components between the amplifier output and the transducers). However, existing methods can only measure this lumped parallel combination and cannot determine the individual coil resistance of each transducer, and therefore the individual coil temperature of each transducer. Summary of the Invention

[0008] Based on the teachings of this disclosure, the disadvantages and problems associated with thermal control of multiple transducers driven by a single amplifier can be reduced or eliminated.

[0009] According to embodiments of the present disclosure, a method may include receiving an input signal, generating an output signal based on the input signal, the output signal being used to drive a plurality of transducers, monitoring physical quantities associated with the plurality of transducers, determining an estimated temperature associated with a first transducer among the plurality of transducers based on the physical quantities, and controlling the output signal based on the estimated temperature.

[0010] According to these and other embodiments of this disclosure, a system may include a temperature estimator and a thermal control subsystem. The temperature estimator may be configured to monitor a physical quantity associated with a plurality of transducers and determine an estimated temperature associated with a first transducer among the plurality of transducers based on the physical quantity. The thermal control subsystem may be configured to generate an output signal based on an input signal for driving the plurality of transducers and to control the output signal based on the estimated temperature.

[0011] According to these and other embodiments of this disclosure, an audio system may include a plurality of transducers, a temperature estimator, and a thermal control subsystem. The temperature estimator may be configured to monitor a physical quantity associated with the plurality of transducers and determine an estimated temperature associated with a first transducer among the plurality of transducers based on the physical quantity. The thermal control subsystem may be configured to generate an output signal based on an input signal for driving the plurality of transducers and to control the output signal based on the estimated temperature.

[0012] The technical advantages of this disclosure will be apparent to those skilled in the art from the accompanying drawings, description, and claims. The objects and advantages of the embodiments will be realized and accomplished, at least by means of the elements, features, and combinations particularly pointed out in the claims.

[0013] It should be understood that the foregoing general description and the following detailed description are illustrative and explanatory, and not limiting of the claims set forth in this disclosure. Attached Figure Description

[0014] A more complete understanding of this embodiment and its advantages can be obtained by referring to the following description taken in conjunction with the accompanying drawings, wherein similar reference numerals indicate similar features, and wherein:

[0015] Figure 1 Selected components of an example system having multiple transducers driven by a single amplifier, according to embodiments of the present disclosure, are shown.

[0016] Figure 2 Selected components of an example system having multiple transducers driven by a single amplifier and thermal protection for such multiple transducers, according to embodiments of the present disclosure, are shown.

[0017] Figure 3 Selected components of an example temperature estimator for feedforward temperature estimation using a thermal model, according to embodiments of the present disclosure, are shown.

[0018] Figure 4 A circuit model of an example parallel transducer circuit according to an embodiment of the present disclosure is shown;

[0019] Figure 5 An example thermal model of a package including a tweeter and a woofer according to an embodiment of the present disclosure is shown, which is modeled as an electrical equivalent circuit model;

[0020] Figure 6 Selected components of an example temperature estimator using feedback temperature estimation according to embodiments of the present disclosure are shown;

[0021] Figure 7 An example overlap processing of two Goertzel filters according to an embodiment of this disclosure is illustrated; and

[0022] Figure 8 An example passive circuit model showing the output impedance observed from the amplifier output terminal according to an embodiment of the present disclosure is illustrated. Detailed Implementation

[0023] Figure 1Selected components of an example system 100 having multiple transducers driven by a single amplifier, according to an embodiment of the present disclosure, are shown. Specifically, system 100 depicts an amplifier 102 configured to drive two audio transducers (specifically a tweeter 104 and a woofer 106), each having its own voice coil. Frequency crossover filtering of the speakers can be achieved using a DC blocking capacitor 108, which, together with the resistance of the tweeter 104, forms a first-order high-pass filter, allowing only higher-frequency audio above the cutoff frequency of this high-pass filter to be received by the tweeter 104. Since both the tweeter 104 and the woofer 106 are driven in parallel by amplifier 102, the impedance measured from a single pair of voltage and current feedback signals from the output of amplifier 102 can be used to calculate the parallel impedance Z of the combination of the woofer 106, tweeter 104, and DC blocking capacitor 108. p Given the following:

[0024]

[0025] Z w The impedance of the 106 subwoofer, Z t ω is the impedance of the tweeter 104, j is the imaginary number equal to the square root of -1, ω is the angular frequency associated with the signal driven by the amplifier 102, and C is the capacitance of the DC blocking capacitor 108.

[0026] For clarity and explanation, Figure 1 A simple first-order frequency divider filter circuit is depicted. It should be understood that other filter circuits, including higher-order and / or more complex filter circuits, can be used.

[0027] In some embodiments, the tweeter 104 and the woofer 106 can be packaged within a single dual transducer module. Furthermore, although Figure 1 Only two transducers (i.e., tweeter 104 and woofer 106) are depicted, but in some embodiments, system 100 may include any suitable number of three or more transducers.

[0028] Figure 2 Selected components of an example system 200 having multiple transducers driven by a single amplifier and thermal protection for such multiple transducers, according to embodiments of the present disclosure, are shown. Figure 2 As shown, system 200 may include a thermal control subsystem 202, a pilot tone injection subsystem 204, an amplifier 102, including a tweeter 104 and a woofer 106 (and a DC blocking capacitor 108, although...) Figure 2 The transducer module (not shown) and temperature estimator 206.

[0029] The thermal control subsystem 202 may include being configured to receive input signals and respond to temperature information associated with the tweeter 104 and the woofer 106 (e.g., the temperature T of the tweeter 104 coil). T and the temperature T of the woofer 106 coil W Any system, device, or apparatus that modifies the input audio signal, as described in more detail below, to minimize thermal damage to the tweeter 104 and woofer 106. For example, the thermal control subsystem 202 may apply attenuation to specific frequency subbands of the input audio signal, apply attenuation across the entire frequency band of the input audio signal, and / or impose power limiting on the input audio signal to maintain the temperature of the tweeter 104 and woofer 106 below critical levels, thereby preventing or minimizing damage to the tweeter 104 and woofer 106.

[0030] The pilot tone injection subsystem 204 may include any system, device, or apparatus configured to inject one or more pilot tones of a specific frequency into an input audio signal, the purpose of which is to determine one or both of the resistance of the voice coil of the tweeter 104 and the resistance of the voice coil of the woofer 106, as described in more detail below.

[0031] Amplifier 102 can receive input audio signals, such as those modified by thermal control subsystem 202 and / or pilot tone injection subsystem 204, and drive the output signal, as a function of the input signal, to tweeter 104 and woofer 106. Although Figure 2 Not shown, but some embodiments of system 200 may include a digital-to-analog converter connected between pilot tone injection subsystem 204 and amplifier 102 to convert a digital input signal into an equivalent analog signal. In other embodiments, amplifier 102 may include such a digital-to-analog converter, or may be otherwise configured to perform such conversion (e.g., a Class D amplifier).

[0032] Temperature estimator 206 may include any system, device, or apparatus configured to monitor the voltage v across the parallel combination of tweeter 104 and woofer 106. MON And the current i supplied to the parallel combination of the tweeter 104 and the woofer 106 MON Based on this, the resistance of one or both of the tweeter 104 coil and the woofer 106 coil is estimated, and the temperature T of the tweeter 104 coil is further estimated from this estimated resistance. T and the temperature T of the woofer 106 coil WThese estimates are then passed to the thermal control subsystem 202. As described in more detail below, in some embodiments, the temperature estimator 206 may employ a feedforward method to estimate the temperature T. T and T W The temperature estimator 206 utilizes the woofer temperature T based on the pilot signal. W The estimate, combined with the thermal model of the packaged modules of tweeter 104 and woofer 106, provides the tweeter temperature T. T The temperature estimator 206 may employ a feedback method to estimate the temperature T, as further described below in some embodiments. T and T W Two pilot tone signals are used: a low-frequency pilot tone within the low-frequency band of the woofer 106, and a high-frequency pilot tone pointing towards the top of the frequency response of the tweeter 104. In this dual-pilot tone method, the temperature estimator 206 can also implement a parallel impedance solver to calculate the independent resistance values ​​of the tweeter 104 and the woofer 106 from the estimates of the parallel impedance of the tweeter 104 and the woofer 106.

[0033] Figure 3 Selected components of an example temperature estimator 206A for feedforward temperature estimation using a thermal model, according to embodiments of the present disclosure, are shown. In some embodiments, the temperature estimator 206A can be used to implement... Figure 2 The temperature estimator 206 is described in the figure. Figure 3 As shown, the temperature estimator 206A may include a pilot tone filter 302, an input power estimator 304, a woofer DC resistance estimator and a resistance-to-temperature converter 306, and a thermal model 308.

[0034] A low-frequency pilot tone (e.g., at 12 Hz) can be applied by the pilot tone injection subsystem 204, and the pilot tone filter 302 can perform filtering to separate the detected voltage v in response to the low-frequency pilot tone. MON and the monitored current i MON The low-frequency components are analyzed, and the resistance Re of the woofer 106 is estimated from these low-frequency components. W In parallel, the input power estimator 304 can be based on the monitored voltage v MON and the monitored current i MON And further based on resistance Re W Estimate the respective input power P delivered by amplifier 102 to tweeter 104 and woofer 106. T and P W As described in more detail below. Furthermore, the woofer DC resistance estimator and resistance-to-temperature converter 306 can measure the resistance Re of the woofer 106.W Convert to estimated temperature T W For example, using the formulas described in the background section of this application, the DC resistance RE of the woofer 106 can be estimated. DC The thermal model 308 can receive temperatures T. W and input power P T and P W Based on this, the final estimated temperature T of the woofer 106 coil is generated. W And the final estimated temperature T of the tweeter 104 coil. T .

[0035] Figure 4 A circuit model 400 of an example parallel transducer circuit for a tweeter 104 and a woofer 106 according to an embodiment of the present disclosure is shown. Figure 4 The functionality of the input power estimator 304 can be demonstrated. The circuit model 400 can be based on the circuit of the example system 100 and includes the trace resistance present in such circuits. Voltage V P It can represent the monitored voltage V MON That is, the voltage and current I across the parallel combination of the tweeter 104 and the woofer 106 as observed by amplifier 102. P It can represent the monitored current I MON This refers to the current flowing through the parallel combination of the tweeter 104 and the woofer 106, as observed by amplifier 102. Circuit model 400 may include a resistor R. TRACE The trace resistor is 402, and the resistor R is... TRACE This represents the trace resistance between the output terminals of amplifier 102 and the parallel combination of the speaker. Circuit model 400 may further include a voltage V representing the estimated voltage across the voice coil of the woofer 106. W The current I represents the estimated current flowing through the 106 voice coil of the woofer. W and a resistance value Re representing the estimated resistance of the woofer 106. W The resistor 406. Circuit model 400 may also include a capacitor 408 having a capacitance value C representing the capacitance of the DC blocking capacitor 108, and a voltage V representing the estimated voltage across the voice coil of the tweeter 104. T The current I represents the estimated current flowing through the 104 voice coil of the tweeter. T and a resistance value Re representing the estimated resistance of the tweeter 104. T The resistor is 404.

[0036] From circuit model 400, the input power estimator 304 can calculate the voltage V across the voice coil of the woofer 106 using the following formula. w :

[0037]

[0038] The input power estimator 304 can then use an admittance filter (e.g., which can be obtained a priori during the characterization of the woofer 106) to estimate the woofer current I. W The admittance filter is the reciprocal of the impedance response of the woofer 106:

[0039]

[0040] The input power estimator 304 can estimate the subwoofer power using the following formula:

[0041]

[0042] The input power estimator 304 can estimate the power consumed by the trace resistance 402 using the following formula:

[0043]

[0044] And the total power consumed by the parallel combination of tweeter 104 and woofer 106 is estimated by the following formula:

[0045]

[0046] The input power estimator 304 can estimate the power of the tweeter 104 and the DC blocking capacitor 108 (e.g., capacitor 408) using the following formula.

[0047]

[0048] From these estimates, the input power estimator 304 can estimate the tweeter current I using the following formula. T :

[0049]

[0050] The input power estimator 304 can model the capacitor 408 as a simple first-order high-pass filter and convert the tweeter voltage V... T The output of this high-pass filter is estimated as follows:

[0051]

[0052] The input power estimator 304 can further use an equalization filter to compensate for overestimation at higher frequencies (e.g., above 10 kHz). This overestimation may occur due to inaccuracies in the admittance filter and other residual errors in the estimation process. This equalization can be tuned during the thermal characterization of system 100 and / or system 200. The input power estimator 304 can estimate the tweeter power using the following formula:

[0053]

[0054] The input power estimator 304 can transmit the power estimates of these woofers and tweeters to the thermal model 308.

[0055] Figure 5 An example thermal model 308 of a package including a tweeter 104 and a woofer 106 according to an embodiment of the present disclosure is shown, modeled as an electrical equivalent circuit model. In embodiments where the tweeter 104 and woofer 106 are integrated in the same package, there may be a degree of thermal coupling between the tweeter 104 and woofer 106 and between them and the air within the housing of the package. Therefore, even if the input audio signal of amplifier 102 is confined to the frequency band of woofer 106, tweeter 104 may be heated due to this thermal coupling, and vice versa. Generally, the voice coil of tweeter 104 can be significantly smaller than that of woofer 106, and therefore its temperature rise may be significantly faster than that of woofer 106.

[0056] Thermal model 308 can assume that the capacitance of the magnet and voice coil of the tweeter 104 can be modeled as a single capacitance. This assumption may be accurate if the thermal resistivity between the coil and the magnet is sufficiently small. Therefore, the thermal capacitance of the tweeter 104 can be dominated by its magnet rather than its coil.

[0057] like Figure 5 As shown, power P IN This can represent the input power of the subwoofer 106, while P T This can represent the input power of the tweeter 104. It has a capacitor C. CW The capacitor 502 can represent the voice coil thermal capacitance of the woofer 106, which has a capacitance C. MW The capacitor 504 can represent the magnet heat capacity of the woofer 106, and has a resistance R. CW The resistor 506 can represent the thermal resistance of the voice coil of the woofer 106, and has a resistance R. MW The resistor 508 represents the thermal resistance of the magnet in the woofer 106. It has a capacitor C. CT The capacitor 510 can represent the voice coil thermal capacitance of the tweeter 104, and has a resistor R.CT The resistance 512 can represent the voice coil thermal resistance of the tweeter 104. Ambient temperature T AMB This indicates the ambient temperature inside the package.

[0058] Thermal coupling between tweeter 104 and woofer 106 can be achieved through resistor R. CW and R MW The modeling involves two aspects: the thermal resistance to the airflow into the encapsulated interior.

[0059] The thermal model 308 can be in state-space form, and the following input vector is defined for the current state x(t) and the excitation u(t). In each iteration, the thermal model 308 can be updated to compute the new state, and this can be calculated using the following formula:

[0060]

[0061] The pre-computed state-space variables of matrix A can be given as:

[0062]

[0063] item The temperature of the tweeter 104 can be correlated with the magnet temperature of the woofer 106 to model the thermal coupling from the woofer 106 to the tweeter 104. In practical applications, it may be useful to correlate the temperatures of the tweeter 104 and the woofer 106 using an adjustable correction factor. Therefore, the thermal model 308 can apply an adjustable correction factor β to correlate the temperatures of the tweeter 104 and the woofer 106. The constants α and β can be obtained a priori during the thermal characterization of system 100 and / or system 200.

[0064] The pre-computed spatial state variables of matrix B can be given as follows:

[0065]

[0066] To illustrate this relationship, consider the initial state of the tweeter 104 with no temperature change and constant power input:

[0067]

[0068] Furthermore, let's assume:

[0069] and

[0070] So:

[0071]

[0072] In some embodiments, heat capacity and thermal resistance values ​​can be obtained a priori through a thermal characterization process. In other embodiments, heat capacity and thermal resistance values ​​can be obtained a priori through a thermal characterization process, followed by iterative tuning to improve the overall accuracy of the thermal model 308.

[0073] Figure 6 Selected components of an example temperature estimator 206B using feedback temperature estimation according to embodiments of the present disclosure are shown. In some embodiments, the temperature estimator 206B may be used to implement Figure 2 The temperature estimator 206 is described in the figure. Figure 6 As shown, the temperature estimator 206B may include a low-frequency (e.g., 12 Hz) pilot tone extractor 602, a high-frequency (e.g., 20 kHz) pilot tone extractor 604, a parallel impedance solver 606, and a resistance-to-temperature converter 608.

[0074] A low-frequency pilot tone (e.g., at 12 Hz) can be applied by the pilot tone injection subsystem 204, and the low-frequency pilot tone extractor 602 can perform filtering to separate the monitored voltage v in response to the low-frequency pilot tone. MON and the monitored current i MON The low-frequency components are used to estimate the resistance Re of the woofer 106. W .

[0075] In parallel, a high-frequency pilot tone (e.g., at 20 kHz) can be applied by the pilot tone injection subsystem 204, and the high-frequency pilot tone extractor 604 can perform filtering to separate the monitored voltage v in response to the high-frequency pilot tone. MON and the monitored current i MON The high-frequency components are used to estimate the impedance Z. H The impedance Z H It could be the impedance Z of the woofer 106. W The impedance Z of the combination of tweeter 104 and DC blocking capacitor 108 T Parallel combinations of phases connected in parallel. In some embodiments, the impedance Z H The Goertzel algorithm can be used to calculate high-frequency pilot tones. For example, the high-frequency pilot tone extractor 604 can extract the detected voltage v. MON and the monitored current i MON By applying the Goertzel filtering algorithm (e.g., at 20 kHz) and temporally overlapping sampling, one Goertzel filter can accumulate more samples while the other is accumulating the output of the first. This approach allows for operation over a larger accumulation window and reduces noise in the complex spectrum values.

[0076] Figure 7 An example of overlapping processing of two Goertzel filters according to an embodiment of the present disclosure is illustrated. For example, after accumulating more than N blocks (where N is a positive integer), the first Goertzel filter of the high-frequency pilot tone extractor 604 can output a result. In parallel, the second Goertzel filter can accumulate samples, but starts with an offset of N / 2 blocks. When the Goertzel filter has accumulated a configured number of samples and output a result, the Goertzel filter can be reset (e.g., the filter accumulator is set to zero) and the next value can be generated from another Goertzel filter. This process can continue alternately between the Goertzel filters.

[0077] Although this document discloses a Goertzel filter with two parallel filters, it is understood that a Goertzel filter can be implemented using more than two parallel filters. For example, in some embodiments, the Goertzel filter may be implemented using four parallel filters with 25% overlap. Furthermore, it is understood that filtering techniques (e.g., standard Fast Fourier Transform) can be used instead of the Goertzel filter described herein.

[0078] The parallel impedance solver 606 can use resistor Re W and impedance Z H The impedance Z of the tweeter 104 is estimated by measurement estimation (further described below) and other physical parameters of the tweeter 104 and woofer 106 (e.g., the capacitance C of the DC blocking capacitor 108, the inductance of the tweeter 104 and woofer 106). T To illustrate the function of the parallel impedance solver 606, refer to... Figure 8 It shows the output impedance Z observed from the output of amplifier 102 according to an embodiment of the present disclosure. OUT Example passive circuit model. For example... Figure 8 As shown, the output impedance Z OUT It can be modeled as the resistance Re of the woofer 106. W and inductor Le W The series combination, along with the capacitance C of the DC blocking capacitor 108 and the resistance Re of the tweeter 104, W and inductor Le W The series combination is connected in parallel.

[0079] Given two pilot tones driven by amplifier 102, using Figure 8 The model shown yields a system of equations that can be solved to determine the resistance Re of the tweeter 104. T At the frequency of the high-frequency pilot tone:

[0080]

[0081] At the frequency of the low-frequency pilot tone:

[0082]

[0083] Assuming the tweeter inductor Le T If it is small enough, then the term jω in the two equations mentioned above... H Le T and jω L Le T It can be ignored.

[0084] At the pilot frequency, the complex terms of the two equations mentioned above can be given as:

[0085]

[0086]

[0087]

[0088]

[0089] Where f pW and f pT These are the frequencies of the high-frequency pilot tone and the low-frequency pilot tone, respectively. The terms for inductor Le and capacitor C can be known a priori (e.g., through thermal characterization or nominal values ​​in the datasheet of system 100).

[0090] Therefore, the system of equations can be rewritten as:

[0091]

[0092]

[0093] The two equations that follow above represent a problem with two equations and two unknowns (i.e., resistance Re). T and Re W A group of solutions that can solve for the resistance Re. T and Re W Furthermore, at the frequency of the low-frequency pilot tone, it can be assumed that... For a smaller inductor Le W So small as to be negligible, and at high-frequency pilot frequencies, it can be assumed that... For a medium capacitance C that is negligible, the following two equations can be simplified to:

[0094]

[0095]

[0096] In solving the resistance Re T At that time, Xiang This may be crucial in deriving the resistance Re. T The correct value may require the introduction of an additional term Z. WH Offset, thus obtaining

[0097]

[0098] This offset could explain why the speaker module might behave differently. Figure 8 The ideal circuit model is not considered, and the impedance of the woofer at high frequencies may be affected by the unmodeled phase shift. Furthermore, the impedance Le used in the aforementioned equations may deviate from the value derived using typical Thiele-Small parametric characterization methods.

[0099] Using known algebraic techniques, the parallel impedance solver 606 can solve for the resistance Re. T and Re W .

[0100] The resistance-to-temperature converter 608 can convert the resistor Re of the tweeter 104. T Convert to estimated temperature T T For example, using the formula described in the background section of this application. In some embodiments, the resistance-to-temperature converter 608 can also convert the resistance Re of the woofer 106... W Convert to estimated temperature T W For example, using the formula described in the background section of this application.

[0101] Furthermore, in parallel with the components of the previously described temperature estimator 206B, the temperature estimator 206B may include components configured to estimate (e.g., based on current i) MON (squared) Input power P of 106 subwoofer W The input power estimator 610. The DC resistance estimator 612 can be based on this input power P. W and the woofer resistance Re estimated by the low-frequency pilot tone extractor 602 W The estimated temperature T of the generated woofer W The estimate can be used to replace or supplement the woofer temperature T provided by thermal model 616. W The estimate.

[0102] In some cases, a pilot signal with a sufficiently high voltage level (e.g., greater than 0.2V) may become audibly perceptible to a listener, or the pilot tone itself may cause additional undesirable heating of the tweeter 104 voice coil. In such cases, as an alternative to using a high-frequency pilot tone, the temperature estimator 206B may include a threshold detector 614, which may be based on the extracted pilot tone signal power P determined by the pilot tone power estimator 605. L and P H The estimation determines the voltage v monitored at high frequencies. MON and the monitored current i MON Does the signal content in the high-frequency pilot tone extractor 604 contain sufficient signal content to generate the estimated impedance Z for input to the parallel impedance solver 606? H If there is sufficient signal content, the tweeter impedance Z... T The impedance can be calculated by the parallel impedance solver 606, and the parallel impedance solver 606 can extract the tweeter impedance Z. T The real part is used to estimate the tweeter resistance Re. T This enables the resistance-to-temperature converter 608 to convert the tweeter resistor Re... T Converted to tweeter temperature T T However, if the signal content is insufficient, thermal model 616 (which is structurally and / or functionally similar to or identical to thermal model 308) can be used to estimate temperature T. T。

[0103] As described above, the thermal control subsystem 202 can respond to the estimated temperature T T and / or estimate temperature T W The input audio signal can be modified to minimize thermal damage to the tweeter 104 and woofer 106. For example, the thermal control subsystem 202 can apply attenuation to specific frequency subbands of the input audio signal, apply attenuation across the entire frequency band of the input audio signal, and / or impose power limiting on the input audio signal to maintain the temperature of the tweeter 104 and woofer 106 below critical levels, thereby preventing or minimizing damage to the tweeter 104 and woofer 106.

[0104] In some embodiments, the thermal control subsystem 202 may apply a full-band thermal limiter to control the temperature of both the tweeter 104 and the woofer 106. In such embodiments, the thermal control subsystem 202 may use an estimated temperature T... T and estimated temperature T WThe maximum value is used as the basis for thermal control, and this maximum value is then used by the thermal control subsystem 202 to attenuate the entire frequency band of the input signal as the temperature increases. Furthermore, in some embodiments of this type, the thermal control subsystem 202 may apply a thermal rate limiter to control the temperature surge of the tweeter 104 caused by energy in higher frequency bands (e.g., human voice), when the estimated temperature T... T and estimated temperature T W When the levels are already very high, this situation can cause problems.

[0105] Because the thermal characteristics (e.g., thermal resistance and thermal capacity) of the tweeter 104 and the woofer 106 may differ, they may actually have different thermal time constants. Consequently, the tweeter 104 and the woofer 106 can heat up and cool down at different rates. For example, due to its smaller size, the tweeter 104 may experience a faster temperature change than the woofer 106. Therefore, a potential improvement to the aforementioned full-band thermal limiting method is to utilize two-stage limiting (e.g., cascaded arrangement) with different attack and decay tuning parameters for each stage. The tweeter 104 can use a faster limiter attack rate, while the woofer 106 has a slower limiter attack rate.

[0106] In these and other embodiments, as a supplement to or alternative to full-band limitation, the thermal control subsystem 202 may employ multi-band limitation. For example, the thermal control subsystem 202 may employ frequency division filtering to divide the input signal into high-frequency and low-frequency bands (e.g., the frequency division point is approximately equal to the crossover frequency between the tweeter 104 and the woofer 106). The thermal control subsystem 202 can then base its analysis on an estimated temperature T. T High-frequency band limitation based on estimated temperature T W The low-frequency band is limited, and then the two thermally controlled sub-band signals are combined, thereby allowing independent control of the temperature of the tweeter 104 and the woofer 106.

[0107] In some embodiments, the thermal control subsystem 202 may perform multi-band limiting using selective acoustic optimization and a multi-band dynamic range compressor in a manner similar to that described in U.S. Patent Application No. 17 / 735,419, filed May 3, 2022, and U.S. Patent Application No. 18 / 334,795, filed June 14, 2023, the entire contents of which are incorporated herein by reference.

[0108] In these and other embodiments, the thermal control subsystem 202 may perform root mean square (RMS) limiting, in which the thermal control subsystem 202 divides the input signal into a high-frequency band and a low-frequency band (e.g., the crossover point is approximately equal to the crossover frequency between the tweeter 104 and the woofer 106), and limits the RMS voltage level in the high-frequency band to a set threshold before recombining the two bands into a single signal, the set threshold varying with the estimated temperature T. W The temperature decreases as the temperature increases. Estimate the temperature T. T This method may not be suitable.

[0109] As used herein, when two or more elements are referred to as “coupled” to each other, the term indicates that the two or more elements are in electronic or mechanical communication (where applicable), whether indirectly or directly connected, with or without intervening elements.

[0110] This disclosure covers all changes, substitutions, variations, alterations, and modifications to the exemplary embodiments herein that will be understood by those skilled in the art. Similarly, where appropriate, the appended claims cover all changes, substitutions, variations, alterations, and modifications to the exemplary embodiments herein that will be understood by those skilled in the art. Furthermore, in the appended claims, references to a device, system, or component adapted to, arranged to, capable of, configured to, enabled to, operable to, or operable to perform a particular function include that device, system, or component, whether or not it or the particular function is activated, turned on, or unlocked, as long as that device, system, or component is so adapted, arranged, capable of, configured to, enabled to, operable to, or operable. Therefore, modifications, additions, or omissions may be made to the systems, devices, and methods described herein without departing from the scope of this disclosure. For example, components of a system and device may be integrated or separate. Furthermore, the operation of the systems and devices disclosed herein may be performed by more, fewer, or other components, and the described methods may include more, fewer, or other steps. Furthermore, the steps may be performed in any suitable order. As used in this document, “each” means each member of a set or each member of a subset of a set.

[0111] Although exemplary embodiments are shown in the accompanying drawings and described below, the principles of this disclosure can be implemented using any number of techniques, whether currently known or not. This disclosure should not be limited in any way to the exemplary embodiments and techniques shown in the drawings and described above.

[0112] Unless otherwise specified, the items depicted in the drawings are not necessarily drawn to scale.

[0113] All examples and conditional language listed herein are intended for educational purposes to aid the reader in understanding the concepts contributed by the inventors to further advance the art, and are not to be construed as being limited to these specifically listed examples and conditions. Although embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions, and modifications can be made thereto without departing from the spirit and scope of the disclosure.

[0114] While specific advantages have been listed above, various embodiments may include some, none, or all of the listed advantages. Furthermore, other technical advantages will become apparent to those skilled in the art upon review of the foregoing figures and description.

[0115] In order to help the Patent Office and any reader of any patent issued under this application interpret the claims appended to this application, the applicants wish to draw attention to the fact that they do not intend for any appended claim or claim element to invoke 35 USC §112(f) unless “means for…” or “steps for…” is expressly used in a particular claim.

Claims

1. A method, the method comprising: Receive input signals; An output signal is generated based on the input signal, and the output signal is used to drive multiple transducers; Monitor the physical quantities associated with the plurality of transducers; Based on the physical quantity, determine the estimated temperature associated with the first transducer among the plurality of transducers; as well as The output signal is controlled based on the estimated temperature.

2. The method according to claim 1, wherein, The physical quantities include the voltage applied to the plurality of transducers and the current supplied to the plurality of transducers.

3. The method according to claim 1 or 2, wherein, The plurality of transducers include a woofer for reproducing low-frequency components and a tweeter for reproducing high-frequency components at frequencies higher than the low-frequency components.

4. The method according to claim 3, wherein, The tweeter and the woofer are integrated into a single integrated speaker module.

5. The method according to any one of claims 1 to 4, further comprising: A first pilot tone is driven on the output signal at a first frequency; Extract the response of the physical quantity in response to the first pilot tone; as well as The estimated temperature is determined based on the response.

6. The method according to claim 5, further comprising: Based on the physical quantities, a first estimated power to be delivered to the first transducer and a second estimated power to be delivered to the second transducer among the plurality of transducers are determined; as well as Based on the estimated temperature, the first estimated power, and the second estimated power, the second estimated temperature of the second transducer is determined from the thermal model of the plurality of transducers.

7. The method according to claim 5 or 6, further comprising: A second pilot tone is driven at a second frequency on the output signal; Extract a second response of the physical quantity in response to the second pilot tone; as well as The estimated temperature and the second estimated temperature of the second transducer among the plurality of transducers are determined based on the response and the second response.

8. A system comprising: Temperature estimator, the temperature estimator being configured to: Monitor physical quantities associated with multiple transducers; as well as Based on the physical quantities, determine the estimated temperature associated with the first transducer among the plurality of transducers; and A thermal control subsystem is configured to: An output signal is generated based on the input signal, and the output signal is used to drive the plurality of transducers; as well as The output signal is controlled based on the estimated temperature.

9. The system according to claim 8, wherein, The physical quantities include the voltage applied to the plurality of transducers and the current supplied to the plurality of transducers.

10. The system according to claim 8 or 9, wherein, The plurality of transducers include a woofer for reproducing low-frequency components and a tweeter for reproducing high-frequency components at frequencies higher than the low-frequency components.

11. The system according to claim 10, wherein, The tweeter and the woofer are integrated into a single integrated speaker module.

12. The system according to any one of claims 8 to 11, further comprising a pilot tone injection subsystem configured to drive a first pilot tone at a first frequency on the output signal, and wherein the temperature estimator is further configured to: Extract the response of the physical quantity in response to the first pilot tone; and The estimated temperature is determined based on the response.

13. The system according to claim 12, wherein, The temperature controller is also configured to: Based on the physical quantities, a first estimated power to be delivered to the first transducer and a second estimated power to be delivered to the second transducer among the plurality of transducers are determined; as well as Based on the estimated temperature, the first estimated power, and the second estimated power, the second estimated temperature of the second transducer is determined from the thermal model of the plurality of transducers.

14. The method according to claim 12 or 13, wherein: The pilot tone injection subsystem is configured to drive a second pilot tone at a second frequency on the output signal; and The temperature estimator is also configured to: Extract a second response of the physical quantity in response to the second pilot tone; and The estimated temperature and the second estimated temperature of the second transducer among the plurality of transducers are determined based on the response and the second response.

15. An audio system, comprising: Multiple transducers; Temperature estimator, the temperature estimator being configured to: Monitor the physical quantities associated with the plurality of transducers; as well as Based on the physical quantities, determine the estimated temperature associated with the first transducer among the plurality of transducers; and A thermal control subsystem is configured to: An output signal is generated based on the input signal, and the output signal is used to drive the plurality of transducers; as well as The output signal is controlled based on the estimated temperature.

16. The audio system according to claim 15, wherein, The physical quantities include the voltage applied to the plurality of transducers and the current supplied to the plurality of transducers.

17. The audio system according to claim 15 or 16, wherein, The plurality of transducers include a woofer for reproducing low-frequency components and a tweeter for reproducing high-frequency components at frequencies higher than the low-frequency components.

18. The audio system according to claim 17, wherein, The tweeter and the woofer are integrated into a single integrated speaker module.

19. The audio system according to any one of claims 15 to 18, further comprising a pilot tone injection subsystem configured to drive a first pilot tone at a first frequency on the output signal, and wherein the temperature estimator is further configured to: Extract the response of the physical quantity in response to the first pilot tone; and The estimated temperature is determined based on the response.

20. The system according to claim 19, wherein, The temperature estimator is also configured to: Based on the physical quantities, a first estimated power to be delivered to the first transducer and a second estimated power to be delivered to the second transducer among the plurality of transducers are determined; as well as Based on the estimated temperature, the first estimated power, and the second estimated power, the second estimated temperature of the second transducer is determined from the thermal model of the plurality of transducers.

21. The audio system according to claim 19 or 20, wherein: The pilot tone injection subsystem is configured to drive a second pilot tone at a second frequency on the output signal; and The temperature estimator is also configured to: Extract a second response of the physical quantity in response to the second pilot tone; and The estimated temperature and the second estimated temperature of the second transducer among the plurality of transducers are determined based on the response and the second response.

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