Calibration method and sound generation module

Abstract

To provide a calibration method for a sound generation module that produces consistent acoustic performance, and the sound generation module.SOLUTION: In the calibration system, the calibration method comprises a step of adjusting the operating frequency fv of the air pulse generation device so that the sound pressure level (SPL) of the air pulse generation device falls within a certain range. The sound generation module includes an air pulse generation device that generates sound by generating a plurality of air pulses at a pulse rate corresponding to the operating frequency.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] This application relates to a calibration method and a sound producing module, and more particularly to a calibration method for a sound producing module that is capable of producing consistent acoustic performance. [Background technology]

[0002] Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims of this application, nor are they admitted to be prior art by inclusion in this section.

[0003] Air-pulse generating (APG) devices may be used as sound generation devices or microspeakers. APG devices may include film structures fabricated by MEMS (Micro-Electro-Mechanical Systems) manufacturing processes. However, manufacturing variations may cause APG devices to produce different acoustic performances. For example, even when applying a drive signal having the same drive amplitude to the same type of APG device, manufacturing variations may cause the APG devices to produce different sound pressure levels.

[0004] Therefore, there is a need to improve upon the prior art. [Prior art documents] [Patent documents]

[0005] 1. United States Patent No. US11,943,585 B2 2. United States Patent No. US12,261,567 B2 3. U.S. Patent No. US12,107,546 B1 Summary of the Invention

[0006] Therefore, a primary objective of this application is to provide a calibration method for sound generation modules that is capable of producing consistent acoustic performance over manufacturing variations, thereby remedying the shortcomings of the prior art.

[0007] One embodiment of the present invention provides a calibration method configured to calibrate a sound-producing module, the calibration method including adjusting an operating frequency of an air-pulse generating device so that a sound pressure level (SPL) of the air-pulse generating device falls within a specific range. The sound-producing module includes an air-pulse generating device configured to produce sound by generating a plurality of air pulses at a pulse rate corresponding to the operating frequency.

[0008] Another embodiment of the present invention discloses a sound generation module including a memory configured to store a calibrated operating frequency and an air pulse generating device configured to produce a sound by generating a plurality of air pulses at a pulse rate corresponding to the calibrated operating frequency. A second calibrated operating frequency is stored in a second memory in a second sound generation module separate from the sound generation module. The calibrated operating frequency is different from the second calibrated operating frequency. A sound pressure level generated by the air pulse generating device according to the calibrated operating frequency is consistent with a second sound pressure level generated by the second air pulse generating device according to a second calibrated operating frequency different from the calibrated operating frequency. The second sound generation module includes a second air pulse generating device.

[0009] These and other objects of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. [Brief explanation of the drawings]

[0010] [Figure 1] 1 illustrates an air pulse generating (APG) device. [Figure 2] 2 illustrates waveforms of a demodulation driving signal and a modulation driving signal of the APG device of FIG. 1. [Figure 3] 1 shows the characteristic curve of the conductance of a virtual valve versus the displacement difference and an AM demodulator for AM demodulation. [Figure 4] An airflow I(t), an air pressure wave P(t), and a virtual valve conductance G(t) are shown. [Figure 5] 2 illustrates a curve of displacement gain versus a ratio of Fr / Fv for the APG device of FIG. 1. [Figure 6] 2 shows the SPL measurement results versus demodulation drive amplitude for the device of FIG. 1. [Figure 7] FIG. 1 is a schematic diagram of a calibration system according to an embodiment of the present invention. [Figure 8] 1 illustrates a schematic diagram of a calibration process according to an embodiment of the present invention. [Figure 9] 1 illustrates a schematic diagram of a sound generation module according to an embodiment of the present invention. [Figure 10] 1 illustrates a schematic diagram of a calibration process according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The contents of U.S. Patent Nos. 11,943,585, 12,261,567, and 12,107,546 are incorporated herein by reference.

[0012] By utilizing the capabilities of an air pulse generator (APG) device and its associated drive signal, it is possible to perform calibration over the operating frequency.

[0013] U.S. Patent No. 11,943,585, filed by the same assignee as the present application, discloses an air pulse generating (APG) device 10, shown in FIG. 1 . The APG device 10 includes a flap pair including a flap 101 and a flap 103. The APG device 10 also includes an actuator 101A disposed on the flap 101 and an actuator 103A disposed on the flap 103. The actuators 101A / 103A are driven by a demodulation driving signal S101 / S103 and a modulation driving signal SM to generate multiple air pulses at an ultrasonic pulse rate. The actuators 101A / 103A include a top electrode and a bottom electrode. The two electrodes receive the demodulation driving signal and the modulation driving signal. In the embodiment shown in FIG. 1, but not limited to, the upper electrode receives the demodulated drive signal S101 / S103 and the lower electrode receives the modulated drive signal SM.

[0014] The modulated drive signal SM drives the flap pair to perform a common mode movement. The demodulated drive signals S101 and S103 drive the flap pair to perform a differential mode movement. z,101 and U z,103 We assume that U and U represent the displacement (in the Z / vertical direction) of flap 101 and flap 103, respectively. z,101 +U z,103 ) / 2, and the differential mode motion may refer to a movement component of the flap pair that is |U z,101 -U z,103 It may also refer to the component of movement of the flap pair that is | / 2.

[0015] A slit 112 is formed between the flap 101 and the flap 103. The flap pair performs a differential mode movement (sometimes abbreviated as differential movement), resulting in ΔU z =|U z,101 -U z,103 When | is greater than the thickness of the flap, an opening (also denoted as 112) is formed. From one perspective, the differential movement of flaps 101 and 103 forms a virtual valve, also denoted as 112. ΔU z When ΔU is small (less than the thickness of the flap) and / or an acoustic impedance / resistance is large, such that the airflow through the virtual valve 112 is negligible, the virtual valve 112 may be considered to be a slit 112, as shown in FIG. 1(a). z When the acoustic impedance / resistance is large (greater than the flap thickness) and / or the acoustic impedance / resistance is small, such that the airflow through the virtual valve 112 is significant, the virtual valve 112 may be considered to be an opening 112, as shown in FIG. 1(b).

[0016] The waveforms of the demodulation drive signals S101 and S103 and the waveform of the modulation drive signal SM are shown in FIG. 2. The waveform of the modulation drive signal SM may be considered to be a (generalized) double sideband with suppressed carrier (DSB-SC), and a definition of "generalized DSB-SC" may be found in U.S. Pat. No. 12,107,546 filed by the applicant of this application, but that definition will not be described herein for the sake of brevity. The waveforms of the demodulation drive signals S101 / S103 may be considered to be, but are not limited to, a square / rectangular wave (similar to a clock signal). It should be noted that the phase relationship between the modulation drive signal and the demodulation drive signal is adaptable and is not limited to the embodiment shown in FIG. 2.

[0017] The demodulation drive signals S101 and S103 may or may not be biased at the same level. When the demodulation drive signals S101 and S103 are biased at the same level, the flap pair may perform a symmetric differential movement without initial deflection. In this case, as shown in FIG. 2( a), the demodulation drive signals S101 and S103 may also be denoted as +SV and −SV. In this application, the denotation “SV” is generally used to refer to the demodulation drive signal, which may represent either S101 or S103. In contrast, when the demodulation drive signals S101 and S103 are biased at different levels, the flap pair will perform an asymmetric differential movement with asymmetric initial deflection. Here, the mechanical initial deflection of the flap corresponds to a voltage bias of / within the demodulation driving signals.

[0018] In one embodiment, assuming that the flap pair performs symmetric differential movement without initial deflection, as shown in FIG. 2( a), the demodulation frequency of the demodulation drive signals S101 / S103 may be half the modulation frequency of the modulation drive signal SM. In another embodiment, assuming that the flap pair performs asymmetric differential movement with asymmetric initial deflection, as shown in FIG. 2( b) (e.g., flap 101 initially deflects toward a first direction (e.g., upward) and flap 103 initially deflects toward a second direction opposite the first direction (e.g., downward), such movement meaning that signal S101 may be biased to a voltage greater than the voltage of signal S103), the demodulation frequency of the demodulation drive signals S101 / S103 may be the same as the modulation frequency of the modulation drive signal SM.

[0019] In this application, the demodulation frequency of the demodulated drive signal is also referred to as the operating frequency of the APG device and is denoted as fv. The ultrasonic pulse rate will be the modulation frequency of the modulated drive signal and will correspond to the operating frequency fv.

[0020] In the embodiment shown in Figure 2(a), the virtual valve 112 is closed during the period corresponding to the demodulation driving signals S101 and S103 being in transition. In the embodiment shown in Figure 2(b), the virtual valve 112 is closed when one of the demodulation driving signals is high and the other of the demodulation driving signals is low. For example, assuming that the flap 101 deflects upward first and the flap 103 deflects downward first in Figure 2(b), the virtual valve 112 is closed when the signal S103 is high and the signal S101 is low.

[0021] As taught by Patent No. 11,943,585, from a modulation perspective, the modulating drive signal SM, which produces common mode motion, leads to the generation of amplitude modulated (AM) waves (pressure fluctuations). From a demodulation perspective, the virtual valve 112, controlled by the demodulating drive signal SV, functions as an acoustic diode for AM demodulation, the function of which is shown in detail in Figures 3 and 4.

[0022] Figure 3 shows the displacement difference ΔU (shown in Figure 3(a)). z The conductance G of the virtual valve 112 valve a (characteristic) curve of the conductance G valve of virtual valve 112 versus the displacement difference ΔU z) and an AM demodulator or an envelope detector for AM demodulation (shown in FIG. 3(b)). In FIG. 3(a), the characteristic curve is either convex or concave, and in particular the displacement difference ΔU z When is larger, the displacement difference ΔU z As increases, the valve conductance G valve increases faster. The characteristic curve of the virtual valve 112 is similar to that of a diode. The virtual valve 112 may be used, for example, as an acoustic diode in connection with AM demodulation. AM demodulation is known in the art. The following describes the similarities between the demodulation operation performed by the APG device and conventional known AM demodulators. In FIG. 3(b), "V I " may be analogous to the AM wave or AM pressure variation, "diode D" may be analogous to the virtual valve 112, "capacitor C" and "resistor R L " represents the ambient acoustic capacitance and acoustic resistance, which together form a low pass filter (LPF), and "Vo" may resemble / correspond to the sound perceived by the human ear.

[0023] In other words, the common mode motion is I Assuming that the virtual valve 112 generates an AM wave or AM pressure variation as a rectifier, the virtual valve 112 acts as a diode "D" (as a rectifier) ​​to generate a unipolar air pulse, and is connected to an acoustic capacitance "C" and an acoustic resistance "R" embedded in the surroundings. L" acts as an LPF, filtering out the ultrasonic component, leaving "Vo" as the audible portion (the portion within the audible spectrum band) that is audible to the human hearing system.

[0024] To understand how the rectifier works, FIG. 4 illustrates an airflow I(t) generated by an APG device, which may be expressed as (or related to) the product of an air pressure wave P(t) and a virtual valve conductance G(t), mathematically: I(t) = P(t) G(t) (Equation 1), demonstrating the effect of the rectifier (implemented by a diode or virtual valve 112) on the AM demodulator or envelope detector.

[0025] It should be noted that the amplitude of the output airflow I(t) will determine the volume of sound that the APG device, as a sound-generating device, can generate. In contrast, according to the concept behind FIG. 4 and Equation 1, the amplitude of the output airflow I(t) will be determined according to both the amplitude of the AM pressure wave P(t) and the amplitude of the conductance G(t) (assuming P(t) is amplitude modulated). The amplitude of the AM pressure wave P(t) is affected by the amplitude of the modulated drive signal, denoted as SMamp. The amplitude of the conductance G(t) is determined by the displacement difference ΔU z The difference in displacement ΔU z is affected at least by the amplitude of the demodulated drive signal, denoted as SVamp.

[0026] It should be noted that SVamp generally represents the demodulation driving amplitude, i.e., the amplitude of the demodulation driving signal SV, sometimes abbreviated as demodulation amplitude. In one embodiment, the demodulation amplitude SVamp may be, but is not limited to, a peak-to-peak voltage, denoted as SVpp, of the demodulation driving signal SV. SMamp generally represents the modulation driving amplitude, i.e., the amplitude of the modulation driving signal SM, sometimes abbreviated as modulation amplitude. In one embodiment, the modulation amplitude SVamp may be, but is not limited to, a peak-to-peak voltage or a root-mean-square voltage of the modulation driving signal SM.

[0027] The volume of the APG device as a sound generating device is determined by the displacement difference ΔU z The difference in displacement ΔU z It can be concluded that will be affected (at least) by the amplitude of the demodulated drive signal SVamp.

[0028] This may be verified by Figure 5, which is taken from Patent No. 11,943,585, which illustrates a curve of volume (in terms of SPL (sound pressure level)) versus SVamp (in terms of SVpp) of an APG device as a sound generating device. From Figure 5, it can be observed that as SVpp increases, the volume also increases.

[0029] In addition to SVamp, the displacement difference ΔU zwill also be affected by the operating frequency fv. When the operating frequency fv approaches (or is closer to) a resonance frequency Fr of the air pulse generating device, under the condition that the amplitudes SVamp and SMamp applied to the actuators are the same, the flaps 101 / 103 will have a larger displacement and the flap pair will have a larger ΔU z will have.

[0030] This may be verified by Figure 6, which illustrates curves of displacement gain (compared to the DC frequency applied to the flap pair) against the Fr / fv ratio (for flap pairs with different quality factors Q) for the APG device 10, where Fr / fv → 1 means that the operating frequency fv approaches a resonance frequency Fr.

[0031] This means that in addition to the amplitude of the demodulated drive signal SVamp or SVpp, the operating frequency fv may also be a factor / parameter that adjusts / influences the volume produced by the APG device.

[0032] It should be noted that in mass production, the volume generated by an APG device may differ from device to device due to manufacturing variations. This means that even if the same SVpp is applied to multiple APG devices manufactured using the same manufacturing process, the volume generated by each APG device may differ from device to device.

[0033] Therefore, a calibration process is needed to calibrate all of the multiple APG devices so that they all produce substantially the same volume.

[0034] Additionally, an APG device may have its own companion driver. To facilitate commercialization of APG devices, an APG device may be integrated with its corresponding driver circuitry to form a module, such as a sound generation module. In a production line, multiple APG devices may be integrated into multiple sound generation modules. These sound generation modules may be mounted in a test / calibration device to perform a calibration process.

[0035] For example, Figure 7 illustrates a schematic diagram of a calibration system 2 according to one embodiment of the present application. The calibration system 2 includes a calibration apparatus 20. The calibration apparatus 20 may be a testing platform or a machine that may measure the acoustic or electrical output of one or more sound-generating modules 22 and adjust one or more parameters of the one or more sound-generating modules 22 to generate the acoustic / electrical output. In the embodiment shown in Figure 7, the sound-generating module 22 may include the APG device 10 and a driver circuit 12.

[0036] In one embodiment, the drive circuit 12 may generate the demodulated drive signal SV and the modulated drive signal SM, including but not limited to the circuitry disclosed in U.S. Pat. No. 12,261,567 and / or U.S. Pat. No. 12,107,546, both of which are filed by the assignee of the present application.

[0037] 5 and 6, in one embodiment, the calibration process or calibration system 2 may be configured to calibrate the operating frequency fv so that multiple sound-generating modules (which may or may not be from the same batch) generate substantially the same volume or a consistent volume, or in particular, the SPL generated by the multiple sound-generating modules is, for example, but not limited to, SPL REF It is within a specific range, such as within ±r% of SPL, where r% may represent the tolerance of the product. REF is the value specified in the data sheet.

[0038] 8 illustrates a schematic diagram of a calibration process 30 according to one embodiment of the present invention, which may be performed by the calibration system 2. The calibration process 30 includes the following steps:

[0039] Step 302: A saturated sound pressure level (SPL) corresponding to a saturation region of the APG device is calculated. SAT Get.

[0040] Step 304: SPL SAT According to the above, a typical sound pressure level (SPL) corresponding to a sensitive region of the APG device is TYP Get.

[0041] Step 306: SPL TYPAccording to the standard driving amplitude SV TYP Get.

[0042] Step 308: SV TYP According to the standard power (a typical power) PW TYP Get.

[0043] Step 312: (SPL / SPL TYP -1) Adjust the operating frequency fv so that it is ≦±a%.

[0044] Step 314: (PW / PW TYP -1) Adjust SVamp so that it is ≦±b%.

[0045] The steps of calibration process 30 may be divided into a preparation phase (including steps 302, 304, 306, and 308) and a calibration phase (including steps 312 and 314). In the preparation phase, calibration device 20 gathers statistics for multiple APG devices, while in the calibration phase, calibration device 20 uses those statistics to perform calibration for each of the multiple APG devices.

[0046] Specifically, in step 302, the calibration device 20 calculates the saturated sound pressure level SPL corresponding to the saturated region of the APG device. SAT may be obtained.

[0047] From FIG. 5, it can be observed that the APG device has a saturation region SAT and a sensitive region SNS. In the sensitive region SNS, under a certain operating frequency fv and modulation driving amplitude SMamp, the volume is sensitive to the variation of the demodulation driving amplitude SVamp / SVpp. When the demodulation driving amplitude SVamp / SVpp is large, the APG device enters the saturation region SAT, whereby a certain amount of increase / decrease in the driving amplitude SVamp / SVpp will not cause an excessive increase / decrease in SPL.

[0048] In other words, in the saturation region SAT, the first slope of the SPL vs. SVpp curve shown in FIG. 5 is smaller than a first value, such as ΔSPL1 / ΔSVpp < m1. That is, in the saturation region SAT, the first increment / decrement (such as ΔSPL1 etc.) of SPL caused by the increment / decrement (such as ΔSVpp etc.) of the demodulation driving amplitude is smaller than a first threshold. In contrast, in the sensitive region SNS, the second slope of the SPL vs. SVpp curve shown in FIG. 5 is larger than a second value, and the second value may be larger than the first value, such as ΔSPL2 / ΔSVpp > m2, and m2 > m1. That is, in the sensitive region SNS, the increment / decrement of SPL (such as ΔSPL2 etc.) caused by the second increment / decrement (such as ΔSVpp etc.) of the demodulation driving amplitude is larger than a second threshold, and the second threshold may be larger than the first threshold.

[0049] Assume that there are M APG devices to be calibrated. In one embodiment, the demodulation drive amplitude SVamp / SVpp of each APG device (among the M APG devices) may be increased to achieve a maximum SPL (ensuring that the APG device operates in the saturation region SAT), where SPL MAX,1 ,…,SPL MAX,M The first SPL is SPL MAX,1 ,…,SPL MAX,M By taking a central statistic of SAT may be obtained, and the central statistic indicates the central tendency of the plurality of first SPLs, and the central tendency may refer to the mean / average, median, or mode of the plurality of first SPLs. For example, SPL SAT =mean(SPL MAX,1 ,…,SPL MAX,M ), and mean(·) represents a mean function, which returns the mean of its input arguments.

[0050] In step 304, the calibration device 20 SAT According to the standard sound pressure level (SPL) corresponding to the sensitivity range (SNS) of the APG device, TYP You may get SPL TYP is an SPL when the APG device in the sensitive region SNS can produce. In one embodiment, the calibration device 20 adjusts the SPL by a certain amount. SAT Reduce SPL SAT by a certain amount), standard sound pressure level SPL TYPFor example, the calibration device 20 may acquire (but is not limited to) SPL TYP make sure that SPL TYP corresponds to the sensitive region SNS), TYP =SPL SAT -20[dB] SPL TYP may be obtained.

[0051] In step 306, the calibration device 20 may find / lower the demodulation drive amplitude SVamp for each of the APG devices (out of the M APG devices), so that each APG device TYP The corresponding demodulation drive amplitudes are SVamp1,…,SVamp M In other words, the calibration device 20 calculates SVamp1, ..., SVamp M whereby the mth APG device (out of the M APG devices) may obtain an SPL TYP Furthermore, the calibration device 20 generates the volume as SVamp1, ..., SVamp M Using a central statistic of TYP For example, the calibration device 20 may acquire (but is not limited to) SV TYP =mean(SVamp1,…,SVamp M ) as the standard drive amplitude SV TYP may be obtained.

[0052] In step 308, once the calibration device 20 has determined the standard drive amplitude SV TYP , the calibration device 20 calculates the standard drive amplitude SV TYP According to the standard power PW TYP For example, but not limited to, the calibration device 20 may obtain a standard drive amplitude SV for the M APG devices. TYPand apply the powers PW1,…,PW M Measure PW1,...,PW M Using the central statistics of TYP may be obtained.

[0053] The preparation phase involves generating SPLs from M APG devices. TYP , S.V. TYP , P.W. TYP and the like, while in the calibration phase, for calibration of each of the APG devices, the SPL TYP , S.V. TYP , and P.W. TYP Use.

[0054] Furthermore, in the preparation phase, the modulation amplitude SMamp and the operating frequency fv are kept constant, and the only parameter to be adjusted is the demodulation amplitude SVamp.

[0055] In step 312, the calibration device 20 adjusts the operating frequency fv of each APG device (such as the m-th APG device), so that the SPL of each APG device / m-th APG device is (SPL / SPL TYP −1)≦±a% (Equation 1), where a% represents the tolerance (range). In one embodiment, a% may be set to 5% or 3.5% depending on one or more practical requirements (including, but not limited to, these).

[0056] It should be noted that in step 312, the calibration device 20 adjusts the operating frequency fv while keeping the modulation amplitude SMamp and the demodulation amplitude SVamp constant. Furthermore, the calibration device 20 adjusts the operating frequency fv while keeping the modulation amplitude SMamp and the demodulation amplitude SVamp constant. TYP Similarly, the demodulation amplitude SVamp may be maintained at a constant value.

[0057] In step 314, the calibration device 20 may fine-tune the demodulation amplitude SVamp in each APG device (such as the m-th APG device), so that the power PW of each APG device / m-th APG device is (PW / PW TYP −1)≦±b% (Equation 2), where b% represents the tolerance (range). In one embodiment, b% may be set to 7% depending on one or more practical requirements (including, but not limited to, these). In one embodiment, calibration device 20 may adjust the demodulation amplitude SVamp by one step at a time, with each step being the finest increment that device 20 is capable of achieving.

[0058] It should be noted that in step 314, the calibration device 20 adjusts the demodulation amplitude SVamp while keeping the modulation amplitude SMamp and the operating frequency fv constant. Furthermore, the calibration device 20 uses SV as an initial value for adjusting the demodulation amplitude SVamp. TYP may also be handled.

[0059] In the embodiment shown in FIG. 8, steps 312 and 314 may be performed iteratively until both the conditions expressed by Equation 1 and Equation 2 are met.

[0060] After completing the calibration process 30, or after the iterations in the calibration process 30 have converged, the calibration apparatus 20 may obtain the calibrated operating frequency f corresponding to the mth APG device. V,cal,m The calibration device 20 may acquire the calibrated operating frequency f in the memory of the sound generation module including the m-th APG device. V,cal,m (value) may be stored.

[0061] When calibration (such as calibration process 30 or calibration process 30′ to be introduced below) is performed on the M APG devices, the M APG devices have different calibrated operating frequencies but generate (substantially) the same SPL. Such a relationship between operating frequency and SPL means that when calibration is performed on the M APG devices, the SPLs generated by the M APG devices will fall within a specific tolerance range, provided that the drive amplitudes SVamp and SMamp are small.

[0062] Referring to Fig. 9, the sound generation module 22 is reproduced in Fig. 9. In Fig. 9, the driving circuit 12 includes a memory 120. The memory 120 stores the calibrated operating frequency f V,cal The drive circuit 12 is configured to store the calibrated operating frequency f V,cal The demodulated drive signal SV and the modulated drive signal SM may be generated according to the above.

[0063] In one embodiment, the driver circuit 12 may generate the signals SV and SM, including but not limited to the circuitry disclosed in commonly assigned U.S. Pat. Nos. 12,261,567 and / or 12,107,546.

[0064] In other words, under the condition that the drive amplitude is consistent, the calibrated operating frequency f V,cal,m and f V,cal,m’ may differ for each individual APG device or sound generating module, and the sound generation level SPL (of the mth APG device or sound generating module and the m'th APG device or sound generating module) m and SPL m’ may be the same after performing a calibration (eg, calibration process 30 or calibration process 30').

[0065] In this application, sound producing levels or powers being constant refers to being within a tolerance range. For example, SPL m and SPL m’ (In Eq. 1, SPL is substituted for SPL m / m’ (by using Equation 1) or SPL REF If the SPL is within ±r%, m and SPL m’ is considered to be constant.

[0066] In particular, the above embodiments are used to explain the concept of this application. Those skilled in the art may make modifications or changes according to the concept and are not limited herein. For example, under circumstances where power consumption is not a major concern, power adjustment / calibration may be omitted.

[0067] 10 illustrates a schematic diagram of a calibration process 30′ according to an embodiment of the present invention. The calibration process 30′, which may be performed by the calibration system 2, is similar to the calibration process 30. It differs from the calibration process 30 in that the power-related steps 308 and 314 are omitted. Compared to the process 30, the calibration process 30′ focuses on adjusting the operating frequency fv to achieve a consistent SPL, and the calibration process 30′ may be adopted in a final test (FT) procedure for mass production of sound generation modules having APG devices.

[0068] In summary, the present invention utilizes the operating frequency relative to the resonant frequency to adjust the displacement (difference) and therefore the volume of the APG device. The operating frequency is taken as an adjustment parameter for calibration. After performing the calibration, the APG device or sound generation module will generate a consistent SPL.

[0069] Those skilled in the art will readily appreciate that numerous modifications and variations of the devices and methods may be made while retaining the teachings of the present invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

Claims

1. 1. A calibration method configured to calibrate a sound generation module, the calibration method comprising: adjusting an operating frequency of the air pulse generating device so that the sound pressure level (SPL) of the air pulse generating device falls within a specified range; the sound generation module includes the air pulse generating device, the air pulse generating device configured to generate sound by generating a plurality of air pulses at a pulse rate corresponding to the operating frequency. Calibration methods.

2. The step of adjusting the operating frequency of the air pulse generating device comprises: obtaining a saturated sound pressure level corresponding to a saturated region of the air pulse generating device; obtaining a standard sound pressure level corresponding to a sensitivity region of the air pulse generating device according to the saturated sound pressure level; obtaining a standard driving amplitude according to the standard sound pressure level; adjusting the operating frequency of the first air pulse generating device so that a first sound pressure level generated by the first air pulse generating device falls within a first specified range; In the saturation region, a first increase in sound pressure level corresponding to an increase in drive amplitude is smaller than a first threshold value; In the sensitivity region, a second increase in sound pressure level corresponding to the increase in drive amplitude is greater than a second threshold value. The calibration method of claim 1.

3. The step of obtaining a sound pressure level in the saturated state corresponding to the saturated region of the air pulse generating device includes: driving a plurality of air pulse generating devices toward the saturation region; obtaining a plurality of second sound pressure levels corresponding to the plurality of air pulse generating devices operating within the saturation region; and obtaining the saturated sound pressure level according to the plurality of second sound pressure levels. The calibration method of claim 2.

4. The step of obtaining the saturated sound pressure level according to the plurality of second sound pressure levels includes: obtaining the saturated sound pressure level as a central statistical value of the plurality of second sound pressure levels; The calibration method according to claim 3.

5. The step of driving the plurality of air pulse generating devices toward the saturation region comprises: adjusting a demodulation drive amplitude for the plurality of air pulse generating devices toward the saturation region while maintaining a modulation drive amplitude and the pulse rate constant; The calibration method according to claim 3.

6. The step of obtaining the standard sound pressure level and the standard driving amplitude according to the saturated sound pressure level includes: obtaining the standard sound pressure level by subtracting a certain amount from the saturated sound pressure level; obtaining the standard drive amplitude corresponding to the standard sound pressure level; The calibration method of claim 2.

7. The step of obtaining the standard drive amplitude corresponding to the standard sound pressure level comprises: obtaining a plurality of drive amplitudes for the plurality of air pulse generating devices such that the plurality of air pulse generating devices generate sound at the standard sound pressure level; obtaining the standard drive amplitude as a median statistic of the plurality of drive amplitudes; The calibration method of claim 6.

8. The step of adjusting the operating frequency comprises: adjusting the operating frequency while maintaining a demodulation drive amplitude and a modulation drive amplitude constant; The calibration method of claim 2.

9. The step of adjusting the operating frequency comprises: adjusting the operating frequency while maintaining a demodulated drive amplitude as the standard drive amplitude. The calibration method of claim 2.

10. further comprising obtaining a standard power corresponding to the standard drive amplitude. The calibration method of claim 2.

11. adjusting a drive amplitude for the air pulse generating device such that the power of the air pulse generating device falls within a second specified range. The calibration method of claim 2.

12. obtaining a calibrated operating frequency; storing the calibrated operating frequency in a memory in the sound generation module. The calibration method of claim 2.

13. a sound generation module, the sound generation module comprising: a memory configured to store a calibrated operating frequency; an air pulse generating device configured to generate sound by generating a plurality of air pulses at a pulse rate corresponding to the calibrated operating frequency; the second calibrated operating frequency is stored in a second memory in a second sound-generating module separate from the sound-generating module; the calibrated operating frequency is different from the second calibrated operating frequency; a sound pressure level generated by the air pulse generating device according to the calibrated operating frequency corresponds to a second sound pressure level generated by a second air pulse generating device according to a second calibrated operating frequency different from the calibrated operating frequency; the second sound-generating module includes the second air pulse generating device; Sound generation module.

14. the calibrated operating frequency and the second calibrated operating frequency are obtained by a calibration process; 14. The sound generation module of claim 13.

15. a drive circuit including a memory and configured to generate a demodulated drive signal and a modulated drive signal according to the calibrated operating frequency; 14. The sound generation module of claim 13.

16. The air pulse generating device comprises: The flap and an actuator disposed on the flap, the actuator including a first electrode and a second electrode; the first electrode and the second electrode receive the demodulated drive signal and the modulated drive signal; the demodulated drive signal and the modulated drive signal are generated according to the calibrated operating frequency; 16. The sound generation module of claim 15.

17. The air pulse generating device comprises: a pair of flaps including a first flap and a second flap; the pair of flaps are driven by the demodulated drive signal to perform differential mode motion and by the modulated drive signal to perform common mode motion; 16. The sound generation module of claim 15.

18. the volume of the sound generated by the air pulse generating device is affected by the demodulated drive amplitude of the demodulated drive signal; 16. The sound generation module of claim 15.

19. a volume of the sound generated by the air pulse generating device is affected by a modulated drive amplitude of the modulated drive signal; 16. The sound generation module of claim 15.

20. the volume of the sound generated by the air pulse generating device is affected by the operating frequencies corresponding to the demodulated drive signal and the modulated drive signal; 16. The sound generation module of claim 15.

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