WO2023198005A1 - 发声装置和电子设备 - Google Patents

发声装置和电子设备 Download PDF

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Publication number
WO2023198005A1
WO2023198005A1 PCT/CN2023/087374 CN2023087374W WO2023198005A1 WO 2023198005 A1 WO2023198005 A1 WO 2023198005A1 CN 2023087374 W CN2023087374 W CN 2023087374W WO 2023198005 A1 WO2023198005 A1 WO 2023198005A1
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WO
WIPO (PCT)
Prior art keywords
sound
frequency
generating device
control signal
pulse
Prior art date
Application number
PCT/CN2023/087374
Other languages
English (en)
French (fr)
Inventor
陈家熠
丁玉江
黎椿键
潘春娇
Original Assignee
华为技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CN202210812781.9A external-priority patent/CN116962942A/zh
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Publication of WO2023198005A1 publication Critical patent/WO2023198005A1/zh

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/06—Loudspeakers

Definitions

  • the present application relates to the field of audio technology, and in particular to a sound-generating device and electronic equipment.
  • Micro speakers are widely used in many current consumer electronics products, providing audio entertainment and enhancing the audio experience for consumers.
  • the sound pressure generated by the vibration of the diaphragm driven by a traditional speaker can be expressed as Where S d is the surface area of the diaphragm, and A is the acceleration of the diaphragm.
  • the sound pressure P is proportional to the product of the surface area S d of the diaphragm and the acceleration A of the diaphragm.
  • a traditional electrodynamic speaker its coils and magnets are used to generate the driving force of the diaphragm.
  • the sound of 1kHz is produced by the diaphragm vibrating at 1kHz on a certain surface area, and the sound of 100Hz is also caused by the diaphragm vibrating at 1kHz.
  • the diaphragm vibrates at 100Hz. If the sound pressure level (SPL) of the two frequencies is the same, the amount of air pushing required for 100Hz is 100 times the amount of air pushing required for 1kHz. In other words, if the amount of air pushing at the two frequencies is the same, the 100Hz sound pressure level is 40dB smaller than the 1kHz sound pressure level.
  • SPL sound pressure level
  • the diaphragm has a consistent displacement in the low-frequency range before the resonance frequency, and the air pushing amount is consistent. Therefore, as the observation frequency doubles, the sound pressure level increases by 12dB. In other words, as the observed frequency is doubled, the sound pressure level decreases by 12dB. For example, if the sound pressure level of a traditional speaker at 400Hz is 90dB under certain test conditions, then under the same test conditions, the sound pressure level at 200Hz is 78dB. Therefore, traditional speakers have obvious low-frequency dive characteristics, and the low-frequency drop reaches -12dB with a large slope, resulting in insufficient low-frequency sound pressure level of the speakers.
  • the present application provides a sound-generating device and electronic equipment using the sound-generating device.
  • the sound-generating device is small in size and forms The audible sound has a higher low-frequency sound pressure level.
  • this application provides a sound-generating device, including a housing, a transducer, a first valve and a control circuit.
  • the housing has an inner cavity and an opening. The opening of the housing connects the inner cavity of the housing with the outside of the housing. space, the transducer is installed in the inner cavity of the shell, and the inner cavity of the shell is divided into a front cavity and a rear cavity. The front cavity is located between the rear cavity and the opening.
  • the first valve is fixed to the shell and covers the shell. Open your mouth.
  • the control circuit is electrically connected to the transducer and the first valve, the control circuit is used to generate a first control signal and a second control signal, the first control signal is configured to drive the vibrating member of the transducer to vibrate, and the second control signal is configured to
  • the switching state of the first valve is controlled so that the sound-generating device emits multiple air pulses to form an audible sound.
  • the frequency of audible sound is lower than the vibration frequency of the vibrating component of the transducer.
  • the multiple air pulses include positive pulses and negative pulses.
  • the sound pressure level of the audible sound changes with the proportion or number of positive pulses and negative pulses. Variety.
  • multiple air pulses form a second sound wave
  • the multiple air pulses of the second sound wave squeeze or relax the air, thereby causing the density of the air to change.
  • the average density change of the second sound wave in the air is consistent with the average density change of the audible sound. Therefore, the second sound wave forms an audible sound in the air, and the audible sound can be transmitted to the human ear.
  • the pulse rate of the second sound wave is higher than the frequency of the desired audible sound. That is, the second sound wave includes multiple air pulses within a single period of the audible sound. This part of the air pulses can fit the audible sound. single cycle waveform.
  • the sound-emitting device no longer uses a traditional speaker structure, but emits a second sound wave including multiple air pulses to form an audible sound.
  • the amplitude adjustment of the audible sound is achieved by controlling the air pulse density of the second sound wave. and frequency adjustment to achieve audio playback.
  • the plurality of air pulses of the second sound wave are realized by the vibration action of the vibrating member of the air pulse generating assembly.
  • the frequency of the audible sound is lower than the pulse rate of the second sound wave, so the frequency of the audible sound is lower than the vibration frequency of the vibrating member. .
  • the displacement required for the vibrating member to vibrate at the pulse rate of the second sound wave is smaller. Since the sound-generating device emits the second sound wave to form an audible sound, the displacement of the vibrating member of the air pulse generating assembly is small.
  • the sound-generating device can adjust the amplitude of the audible sound by adjusting the air pulse density of the second sound wave.
  • the sound pressure level adjustment of the audible sound does not need to rely on the displacement or surface area of the vibrating member. Therefore, the sound-generating device uses the air pulse generating component to adjust the amplitude of the audible sound.
  • the small displacement vibration of the vibrating component and the higher air pulse density of the second sound wave can obtain audible sound with high sound pressure level.
  • the low-frequency frequency response of the sound-generating device does not exist or basically does not have drop characteristics. The drop is significantly lower than 12dB, and the sound-generating device can have a high low-frequency sound pressure level in a small size. Small sound-generating devices have wider applicability in scenes with space requirements.
  • the sound pressure level of audible sound is positively related to the air pulse density. For example, within a certain period of time, the greater the density of positive pulses, it means that the audible sound pressure in that period is positive and the amplitude is larger. On the contrary, the greater the density of negative pulses, it means that the audible sound pressure in that period is positive.
  • the sound pressure is negative, and the greater the amplitude, the period during which positive pulses and negative pulses continuously switch corresponds to a smaller amplitude of audible sound, and the amplitude is an absolute value.
  • the density of positive pulses refers to the difference in the number of positive pulses and negative pulses within a certain period of time.
  • the density of negative pulses refers to the difference in the number of negative pulses and positive pulses within a certain period of time.
  • Air pulse density refers to the difference in quantity between positive and negative pulses of multiple air pulses within a certain period of time, and the quantity difference is an absolute value.
  • the sound pressure level of the audible sound changes with the change of the air pulse density of the second sound wave, that is, the amplitude of the audible sound is adjusted by the air pulse density of the second sound wave, and the frequency change of the audible sound is adjusted by the air pulse density of the second sound wave. Changes in the amplitude of the audible sound are produced, and therefore the frequency of the audible sound can be adjusted by adjusting the air pulse density of the second sound wave.
  • the sound pressure level of the audible sound changes as a function of the air pulse density of the second sound wave.
  • the greater the air pulse density of the second sound wave the higher the sound pressure level of the audible sound.
  • the smaller the air pulse density the lower the sound pressure level of the audible sound.
  • the adjustment method of air pulse density includes but is not limited to: adjusting the ratio of positive pulse and negative pulse within a certain period of time. proportion, and/or adjust the number of positive pulses, and/or adjust the number of negative pulses. Adjusting the ratio of positive pulses to negative pulses includes adjusting the ratio of positive pulses to negative pulses, or adjusting the ratio of positive pulses to the total number of air pulses, or adjusting the ratio of negative pulses to the total number of air pulses. For example, within a certain period (such as the first period), the greater the difference between the number of positive pulses and negative pulses, the higher the audible sound pressure level; the smaller the difference between the number of positive pulses and negative pulses, the higher the audible sound pressure level.
  • the situation where the difference between the number of positive pulses and negative pulses is large includes that the number of positive pulses is significantly larger than the number of negative pulses, or is significantly smaller than the number of negative pulses.
  • the sound pressure levels of the positive and negative pulses of multiple air pulses are the same.
  • the sound pressure level of audible sound is adjusted by adjusting the air pulse density.
  • the amplitude of the first control signal By setting the amplitude of the first control signal to be constant, the amplitude of the vibrating member driving the transducer is constant, thereby generating positive pulses and negative pulses with constant amplitude.
  • the working frequency band of the vibrating component of the transducer is a narrow frequency band, and the vibrating component only needs to have a high response at a single point. Therefore, the transducer can better utilize the resonance frequency of the vibrating component to achieve response, thereby improving energy conversion. efficiency, which helps to increase the sound pressure level.
  • the sound pressure level adjustment of the audible sound can also be achieved by adjusting the air pulse density and the sound pressure level of the air pulse at the same time. At this time, the adjustable range of the audible sound pressure level is wider, and the sound-generating device has a wider applicable range and usage scenarios.
  • the second sound wave of the sound-generating device is an ultrasonic wave
  • the pulse rate of the second sound wave can be higher than 20 kHz.
  • the multiple air pulses of the second sound wave can better fit the waveform of the audible sound, making the sound pressure level of the audible sound high. , and the distortion is small.
  • the frequency of the audible sound is mid-low frequency (20Hz-2000Hz)
  • the pulse rate of the second sound wave has a large multiple difference with the frequency of the audible sound, and the second sound wave can form a sound with high sound pressure level and low distortion. Listen.
  • the second sound wave of the sound-generating device can also be an audible sound wave (less than 20 kHz), and the pulse rate of the second sound wave has a certain multiple of the frequency of the audible sound that is expected to be formed.
  • the pulse rate of the second sound wave can be in the range of 10kHz to 20kHz, so that the sound pressure level of the audible sound formed by the second sound wave is higher. , the distortion is smaller.
  • the transducer is used to generate the first sound wave driven by the first control signal.
  • the first valve is used to open and close under the control of the second control signal; when the first valve is opened, part of the first sound wave formed by the transducer passes through the first valve, forming an air pulse sent to the outside of the sound-generating device. ; When the first valve is closed, the first sound wave formed by the transducer is blocked by the first valve and cannot spread to the outside of the sound-generating device.
  • the sound-generating device selectively emits part of the first sound wave through cooperation between the transducer and the first valve to form a plurality of air pulses, thereby forming a second sound wave.
  • the first sound wave is the basic sound wave of the second sound wave
  • the frequency of the first control signal is set to the ultrasonic frequency
  • the first sound wave is the initial ultrasonic wave to selectively emit part of the sound wave through the cooperation of the transducer and the first valve.
  • the initial ultrasonic wave forms multiple air pulses, so that the second sound wave emitted by the air pulse generating component is a modulated ultrasonic wave.
  • the first sound wave may be an audible sound wave or an ultrasonic wave.
  • the frequency of the first control signal is greater than or equal to 20 kHz and the amplitude remains unchanged.
  • the vibrating component of the transducer can vibrate back and forth driven by the first control signal, and the vibration frequency of the vibrating component is greater than or equal to 20 kHz, that is, the vibration frequency of the vibrating component is an ultrasonic frequency, and the amplitude of the vibrating component remains unchanged, forming an amplitude Unchanged initial ultrasound.
  • the frequency of the second control signal is greater than or equal to twice the frequency of the first control signal.
  • the first valve can achieve at least two switch state selections in one reciprocating vibration of the vibrating component of the air pulse sound-generating assembly, and the sound-generating device can smoothly send out positive pulses, and/or negative pulses, and/or zero pulses.
  • Secondary sound waves can achieve frequency adjustment and amplitude adjustment of audible sound through the adjustment of air pulse density.
  • the frequency of the second control signal is equal to twice the frequency of the first control signal, and the maximum density of positive pulses is the same as the frequency of the first control signal.
  • the sound-generating device further includes a second valve.
  • the second valve is provided on the transducer or the housing. When the second valve is opened, it connects the front chamber and the rear chamber. When the second valve is opened, acoustic communication between the front chamber and the rear chamber is formed.
  • control circuit is electrically connected to the second valve, and the control circuit is also used to generate a third control signal.
  • the second valve can be opened according to any rules to achieve pressure balance between the front chamber and the rear chamber.
  • the setting of the switching time, switching duration and switching frequency of the switching state of the second valve are relatively flexible, and the third control signal is less restricted by the first control signal and the second control signal.
  • the third control signal is used to control the opening period of the second valve to be less than or equal to twenty times the period of the first control signal to ensure that the pressure state of the front chamber and the rear chamber of the air pulse generating assembly can meet the basic requirements for smooth vibration of the vibrating component. It is necessary to reduce the distortion degree of vibration of vibrating components.
  • the minimum width of the conductive cross-section when the second valve is opened is greater than the thickness of the viscous layer d ⁇ , and the thickness of the viscous layer f is the frequency of the first control signal.
  • the minimum width of a conductive section refers to the dimension at the narrowest position of the conductive section.
  • the transducer or the housing is provided with a communication hole, and the communication hole connects the front chamber and the rear chamber.
  • the communication hole is used to achieve air pressure balance between the front cavity and the back cavity, so that the transducer can vibrate smoothly, thereby forming a first sound wave with a small degree of distortion driven by the first control signal.
  • the minimum width of the connected hole is greater than the thickness of the viscous layer d ⁇ , and the thickness of the viscous layer f is the frequency of the first control signal.
  • the minimum width of a communication hole refers to the size at the narrowest position of a single communication hole.
  • the front cavity and the back cavity are not connected to each other.
  • the front chamber and the rear chamber are always separated and disconnected.
  • the casing is provided with a front leakage hole, which connects the front cavity of the casing and the external space of the casing. Through the arrangement of the front leakage hole, the pressure balance between the front cavity of the housing and the external space of the housing is maintained, so that the vibrating component of the transducer can vibrate smoothly and form sound waves.
  • the sound-generating device may also be provided with a second damping mesh.
  • the second damping mesh may be fixed to the casing through bonding or other methods, and cover the front leakage hole.
  • the second damping mesh is breathable, so that the air pulse generating component can still achieve air pressure balance between the front chamber and the external space of the housing through the front leakage hole.
  • the second damping mesh can achieve acoustic isolation between the front cavity and the external space of the casing, so that the sound waves in the front cavity will not leak to the external space of the casing.
  • the number, shape, etc. of the second damping mesh are adapted to the front leak hole.
  • the sound-generating device may not be provided with the second damping mesh.
  • the housing is provided with a rear leak hole, and the rear leak hole connects the rear cavity of the housing and the external space of the housing.
  • the rear leakage hole is used to achieve air pressure balance between the rear chamber and the external space of the casing.
  • the sound-generating device may also be provided with a first damping mesh.
  • the first damping mesh may be fixed to the housing through bonding or other methods, and cover the rear leak hole.
  • the first damping mesh is breathable, so that the air pulse generating component can still achieve air pressure balance between the rear chamber and the external space of the housing through the rear leak hole.
  • the first damping mesh can achieve acoustic isolation between the rear cavity and the external space of the housing, so that the sound waves in the rear cavity will not leak to the external space of the housing.
  • breathability means that the media on both sides of the interface can be exchanged, and acoustic isolation means that sound cannot penetrate.
  • the number, shape, etc. of the first damping mesh are adapted to the rear leak holes.
  • the sound-generating device may not be provided with the first damping mesh.
  • the frequency of the first control signal is less than 400 kHz, so that the sound-generating device forms an audible sound with a frequency in the range of 20 Hz to 2 kHz.
  • the frequency design of the first control signal can make the loss of the second sound wave The level of realism is lower, and the sound pressure level of the audible sound is higher.
  • the frequency of the first control signal is greater than or equal to 400 kHz, so that the sound-generating device forms an audible sound with a frequency in the range of 20 Hz to 20 kHz.
  • the frequency design of the first control signal can make the distortion of the second sound wave lower and the sound pressure level of the audible sound higher.
  • the resonant frequency of the vibrating component of the transducer is set to be consistent with the desired third sound wave.
  • the frequency of the sound wave is the same or similar to the frequency of the first control signal, which can improve the response of the vibrating component of the transducer to the first control signal.
  • the energy utilization rate is high, which is beneficial to improving the audible sound. sound pressure level.
  • the Q value is called the quality factor, and a high Q value means low sound wave energy loss (the attenuation rate is proportional to the square of the frequency).
  • the transducer includes a support member, a diaphragm, and a piezoelectric sheet.
  • the periphery of the diaphragm is fixed to the support member, and the piezoelectric sheet is fixed to the middle of the diaphragm.
  • the piezoelectric sheet can be a single crystal piezoelectric sheet or a dual crystal piezoelectric sheet. Among them, the resonance frequency of the vibration component formed by the diaphragm and the piezoelectric sheet is less than 400 kHz.
  • the transducer includes a support member and a piezoelectric sheet, and the piezoelectric sheet is fixed to the support member.
  • the piezoelectric sheet can be a single crystal piezoelectric sheet or a dual crystal piezoelectric sheet. Among them, the resonant frequency of the piezoelectric piece is greater than or equal to 400kHz.
  • the transducer includes a support, a diaphragm, and a plurality of piezoelectric sheets.
  • the periphery of the diaphragm is fixed to the support.
  • the plurality of piezoelectric sheets are fixed to the middle of the diaphragm.
  • the plurality of piezoelectric sheets are The resonant frequencies are the same.
  • the resonance frequency of the vibration component formed by the diaphragm and the plurality of piezoelectric sheets is greater than or equal to 400 kHz.
  • the vibration component of the transducer includes a base material and multiple piezoelectric elements.
  • the base material is made of polymer material, and the multiple piezoelectric elements are embedded in the base material.
  • the resonance frequency of the vibrating component is greater than or equal to 400kHz.
  • the transducer uses a polyvinylidene fluoride piezoelectric film transducer, a capacitive micromachined transducer, or a piezoelectric micromachined transducer.
  • the resonant frequency of the vibrating component of the transducer is greater than or equal to 400kHz.
  • the sound-generating device includes multiple transducers, and the multiple transducers are installed in the inner cavity of the housing and are located between the front cavity and the rear cavity.
  • the resonance frequencies of the vibrating components of the multiple transducers are the same and are greater than or equal to 400 kHz.
  • the frequency of the first control signal is the same as the resonant frequency of the vibrating component of the transducer, so that the first sound wave and the first control signal have a high matching degree, which is beneficial to increasing the sound pressure level that can be improved.
  • the transducer includes a vibrating member, and the vibrating member is configured to reciprocate driven by the first control signal to form the first sound wave.
  • the first sound wave may be an ultrasonic wave or an audible sound wave.
  • the distance between the first valve and the vibrating member in the vertical direction of the vibrating member is less than ⁇ /2, where ⁇ is the wavelength of the first sound wave.
  • the distance between the first valve and the vibrating member will affect the phase delay of the first sound wave.
  • the first sound wave can be reduced. The loss when the wave is transmitted in the front cavity improves the problems of easy distortion and large energy loss of the second sound wave, improves the energy conversion efficiency of the air pulse generating component, and helps to increase the sound pressure level of audible sound.
  • the height of the back cavity is in the range of M* ⁇ + ⁇ /4- ⁇ /8 to M* ⁇ + ⁇ /4+ ⁇ /8, and ⁇ is the The wavelength of a sound wave, M is a natural number.
  • the phase of the sound wave reflected by the rear cavity is the same as or similar to the phase of the first sound wave. The superposition of the sound wave reflected by the rear cavity and the first sound wave produces an enhancement effect, which is beneficial to increasing the sound pressure level of the audible sound.
  • the height H2 of the back cavity may be in the range of M* ⁇ + ⁇ /4- ⁇ /9 to M* ⁇ + ⁇ /4+ ⁇ /9, or in the range of M* ⁇ + ⁇ /4- ⁇ /10 to Within the range of M* ⁇ + ⁇ /4+ ⁇ /10, in order to obtain better sound wave superposition effect and higher audible sound pressure level.
  • the height H2 of the back cavity is outside the range of M* ⁇ + ⁇ /2- ⁇ /8 to M* ⁇ + ⁇ /2+ ⁇ /8 to avoid the back cavity
  • the superposition of the reflected sound wave and the first sound wave creates a cancellation problem to reduce the distortion of the second sound wave.
  • the height H2 of the back cavity should be outside the range of M* ⁇ + ⁇ /2- ⁇ /9 to M* ⁇ + ⁇ /2+ ⁇ /9, or within the range of M* ⁇ + ⁇ /2- ⁇ /10 to outside the range of M* ⁇ + ⁇ /2+ ⁇ /10.
  • the sound-generating device is also provided with a sound-absorbing component, and the sound-absorbing component is installed in the rear cavity.
  • the sound-absorbing member may be sound-absorbing cotton, a local resonance sound-absorbing structure, or other sound-absorbing structures.
  • the setting of sound absorbing parts can weaken or eliminate the first sound wave emitted by the vibrating member to the rear cavity, thereby weakening or eliminating the reflected sound wave from the rear cavity, and reducing the influence of the reflected sound wave from the rear cavity on the second sound wave to increase the sound pressure level of audible sound. .
  • the audible sound pressure level increased by more than 3dB, while the distortion was reduced.
  • the height of the back cavity is less than ⁇ /4.
  • the air pulse generating assembly sets a sound absorbing member in the rear cavity to weaken or eliminate the reflected sound wave in the rear cavity, thereby reducing the distortion of the second sound wave, and can make the height of the rear cavity less than ⁇ /4, thereby reducing the air pulse generating assembly.
  • the overall height is conducive to the miniaturization of air pulse generating components and sound-generating devices.
  • the sound-generating device also includes a signal processing circuit.
  • the signal processing circuit is used to convert the audio signal into a target air pulse signal based on a pulse density modulation algorithm.
  • the control circuit is used to form a first control signal based on the target air pulse signal. and a second control signal.
  • the pulse density modulation algorithm represents the amplitude of the audio signal through the density of the corresponding area of the target air pulse signal.
  • the target air pulse signal carries information about the target air pulse, and the target air pulse is used to form a sound wave corresponding to the audio signal.
  • the target air pulse signal may include at least one of a positive pulse signal, a zero pulse signal, and a negative pulse signal.
  • the positive pulse signal corresponds to the positive pulse in the target air pulse
  • the negative pulse signal corresponds to the negative pulse in the target air pulse
  • the zero pulse signal corresponds to the zero pulse in the target air pulse.
  • the target air pulse signal may not include a zero pulse signal.
  • the target air pulse signal includes a positive pulse signal and a negative pulse signal
  • the target air pulse signal includes a positive pulse signal, a zero pulse signal, and a negative pulse signal
  • the greater the density of the positive pulse signal the greater the density of the positive pulse signal, which represents the corresponding audio signal in the area. is positive, and the greater the amplitude; conversely, the greater the density of the negative pulse signal, it means that the audio signal in this area is negative, and the greater the amplitude, the area where the positive pulse signal and the negative pulse signal continuously convert corresponds to the amplitude of the audio signal
  • the value is small and the amplitude is an absolute value.
  • the density of positive pulse signals refers to the number of positive pulse signals within a certain period of time.
  • the density of negative pulse signals refers to the number of positive pulse signals within a certain period of time.
  • the present application also provides an electronic device, including any one of the sound-generating devices mentioned above.
  • the audible sounds emitted by electronic devices have high sound pressure levels.
  • Figure 1 is a schematic block diagram of the sound-generating device provided by the embodiment of the present application in some embodiments;
  • FIG. 2 is a schematic diagram 1 of the sound generation principle of the sound generation device shown in Figure 1;
  • Figure 3 is a schematic diagram 2 of the sound-generating principle of the sound-generating device shown in Figure 1;
  • Figure 4 is a schematic structural diagram of the air pulse generating component of the sound-generating device shown in Figure 1 in some embodiments;
  • Figure 5 is a schematic diagram of the sound-generating device shown in Figure 1 in some states of use;
  • Figure 6 is a schematic diagram of the internal structure of the air pulse generating assembly shown in Figure 4 in some states of use;
  • Figure 7 is a schematic diagram of the internal structure of the air pulse generating assembly shown in Figure 4 in other states of use;
  • Figure 8 is a schematic diagram of the sound-generating device shown in Figure 1 in other usage states
  • Figure 9 is a schematic diagram of the internal structure of the air pulse generating assembly shown in Figure 4 in some states of use;
  • Figure 10 is a schematic diagram of the internal structure of the air pulse generating assembly shown in Figure 4 in other states of use;
  • Figure 11 is a schematic diagram of the sound-generating device shown in Figure 1 in other usage states;
  • Figure 12 is a schematic diagram of the first modulation rule of the sound-generating device shown in Figure 1;
  • Figure 13 is a schematic diagram of the second modulation rule of the sound-generating device shown in Figure 1;
  • Figure 14 is a schematic diagram of the third modulation rule of the sound-generating device shown in Figure 1;
  • Figure 15 is a schematic diagram of the fourth modulation rule of the sound-generating device shown in Figure 1;
  • Figure 16 is a schematic diagram of the internal structure of the air pulse generating assembly shown in Figure 4.
  • Figure 17 is a schematic diagram of the internal structure of the air pulse generating assembly shown in Figure 1 in other embodiments;
  • Figure 18 is a schematic diagram of the internal structure of the air pulse generating assembly shown in Figure 1 in other embodiments;
  • Figure 19 is a schematic diagram of the internal structure of the air pulse generating assembly shown in Figure 18;
  • Figure 20 is a schematic diagram of the internal structure of the air pulse generating assembly shown in Figure 1 in other embodiments;
  • Figure 21 is a schematic diagram of the internal structure of the air pulse generating assembly shown in Figure 1 in other embodiments;
  • Figure 22 is a schematic diagram of the internal structure of the air pulse generating assembly shown in Figure 1 in other embodiments;
  • Figure 23 is a schematic structural diagram of the ultrasonic transducer provided by the embodiment of the present application in some embodiments.
  • Figure 24 is a schematic structural diagram of the ultrasonic transducer provided by the embodiment of the present application in other embodiments;
  • Figure 25 is a schematic structural diagram of the ultrasonic transducer provided by the embodiment of the present application in other embodiments;
  • Figure 26 is a schematic structural diagram of the ultrasonic transducer provided by the embodiment of the present application in other embodiments;
  • Figure 27 is a partial structural schematic diagram of the ultrasonic transducer shown in Figure 26;
  • Figure 28 is a schematic structural diagram of the ultrasonic transducer provided by the embodiment of the present application in other embodiments;
  • Figure 29 is a partial structural schematic diagram of the ultrasonic transducer shown in Figure 28;
  • Figure 30 is a schematic structural diagram of the air pulse generating assembly shown in Figure 1 in other embodiments;
  • Fig. 31 is a partial structural diagram of the air pulse generating assembly shown in Fig. 30.
  • first, second and other words are used for descriptive purposes only and cannot be understood as implying or implying the relative importance or implicitly indicating the quantity of the indicated technical features. Therefore, features defined as “first” and “second” may explicitly or implicitly include one or more of these features.
  • orientation terms mentioned in the embodiments of this application such as “upper”, “lower”, “inner”, “outer”, “side”, “top”, “bottom”, etc., are only for reference to the directions of the drawings. , therefore, the orientation terms used are for the purpose of better and clearer description and understanding of the embodiments of the present application, but do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, therefore It cannot be understood as a limitation on the embodiments of this application.
  • connection can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium.
  • electrical connection means that electrical signals can be conducted between each other.
  • Embodiments of the present application provide a sound-generating device and an electronic device using the sound-generating device.
  • the sound-producing device uses no Different from the sound generation method of traditional speakers, the sound-generating device emits multiple air pulses to form audible sound.
  • the frequency of the audible sound is lower than the vibration frequency of the transducer of the sound-generating device.
  • the sound pressure level of the audible sound is determined by multiple air pulses.
  • the pulsed air pulse density is adjusted to achieve a higher low-frequency sound pressure level in a small volume.
  • the electronic devices can be mobile phones, tablets, hearing aids, smart wearable devices and other electronic devices that need to output audio through a sound-generating device.
  • Smart wearable devices can be smart watches, augmented reality (AR) glasses, AR helmets or virtual reality (VR) glasses, etc.
  • the sound-generating device can also be used in the whole house, smart home, automobile and other fields, and used as audio equipment or part of the audio equipment.
  • FIG. 1 is a schematic block diagram of the sound-generating device 100 provided by the embodiment of the present application in some embodiments.
  • FIG. 2 is a schematic diagram 1 of the sound-generating principle of the sound-generating device 100 shown in FIG. 1 .
  • the sound-generating device 100 includes a signal processing circuit 10 , a control circuit 20 and an air pulse generating component 30 .
  • the signal processing circuit 10 is used to convert the audio signal into a target air pulse signal.
  • the signal processing circuit 10 can convert the audio signal into a target air pulse according to a pulse density modulation (Pulse Density Modulation, PDM) algorithm.
  • PDM pulse density modulation
  • the audio signal can be output by the audio source.
  • the audio signal can be a digital signal or an analog signal. When the audio signal is an analog signal, the audio signal can be converted into a digital signal by an analog-to-digital conversion circuit.
  • the analog-to-digital conversion circuit can be a part of the signal processing circuit 10 or another circuit independent of the signal processing circuit 10. Embodiments of the present application This is not strictly limited.
  • the control circuit 20 is used to form a control signal according to the target air pulse signal, and the air pulse generating component 30 is used to send out a plurality of air pulses according to the control signal, thereby forming audible sound.
  • the sound-generating device 100 may be a modular component, and its signal processing circuit 10 and control circuit 20 may be integrated into the circuit components of the sound-generating device 100.
  • the circuit components may generally include one or more circuit boards and one or more chips and their components. Matching components.
  • the signal processing circuit 10 and/or the control circuit 20 of the sound-generating device 100 can also be fixed or integrated into other components of the electronic device. Embodiments of the present application This is not strictly limited.
  • the pulse density modulation algorithm represents the amplitude of the audio signal through the density of the corresponding area of the target air pulse signal.
  • the target air pulse signal carries information about the target air pulse, and the target air pulse is used to form a sound wave corresponding to the audio signal.
  • the target air pulse signal may include at least one of a positive pulse signal, a zero pulse signal, and a negative pulse signal.
  • the positive pulse signal corresponds to the positive pulse in the target air pulse
  • the negative pulse signal corresponds to the negative pulse in the target air pulse
  • the zero pulse signal corresponds to the zero pulse in the target air pulse.
  • the target air pulse signal may not include a zero pulse signal.
  • the positive pulse signal and the negative pulse signal are represented by 1 and -1. In other cases, positive pulse signals and negative pulse signals can also be represented by 1 and 0.
  • the target air pulse signal includes a positive pulse signal and a negative pulse signal
  • the target air pulse signal includes a positive pulse signal, a zero pulse signal, and a negative pulse signal
  • the greater the density of the positive pulse signal the greater the density of the positive pulse signal, which represents the corresponding audio signal in the area. is positive, and the greater the amplitude; conversely, the greater the density of the negative pulse signal, it means that the audio signal in this area is negative, and the greater the amplitude, the area where the positive pulse signal and the negative pulse signal continuously convert corresponds to the amplitude of the audio signal
  • the value is small and the amplitude is an absolute value.
  • the density of positive pulse signals refers to the number of positive pulse signals within a certain period of time (that is, within a certain time window, illustrated by a dotted box in Figure 2).
  • the density of negative pulse signals refers to the number of positive pulse signals within a certain period of time (that is, within a certain time window).
  • the air pulse generating component 30 forms a second sound wave according to the control signal.
  • the second sound wave includes a plurality of air pulses.
  • the air pulses have a certain sound pressure level, so that the second sound wave forms an audible sound.
  • multiple air pulses of the second sound wave squeeze or relax the air, thereby causing the density of the air to change.
  • the average density change of the second sound wave in the air is consistent with the average density change of the audible sound. Therefore, the second sound wave forms an audible sound in the air, and the audible sound can be transmitted to the human ear.
  • the pulse rate of the second sound wave is higher than the frequency of the desired audible sound, that is, the second sound wave has a pulse rate higher than the frequency of the audible sound.
  • the cycle includes multiple air pulses, and these air pulses can fit the waveform of a single cycle of audible sound. For example, if the pulse rate of the second sound wave is 40kHz, the frequency of the audible sound expected to be formed is 100Hz.
  • average density refers to the average density of air within a certain period of time at a certain location in space, or the average density of air within a certain spatial range at a certain moment in time.
  • the multiple air pulses of the second sound wave include positive pulse P1, null pulse P0 (coinciding with the coordinate axis, not marked in the figure) and negative pulse (negative pulse)P-1.
  • the positive pulse P1 and the negative pulse P-1 have the same amplitude.
  • the sound pressure level of the audible sound (eg, corresponding to the waveform amplitude in Figure 2) is positively related to the air pulse density. For example, within a certain period of time, the greater the density of the positive pulse P1, it means that the audible sound pressure in that period is positive and the amplitude is larger. On the contrary, the greater the density of the negative pulse P-1, it means that the audible sound pressure in that period is positive.
  • the sound pressure of the audible sound is negative, and the greater the amplitude, the period during which the positive pulse P1 and the negative pulse P-1 continuously switch corresponds to a small amplitude of the audible sound, and the amplitude is an absolute value.
  • the density of positive pulses P1 refers to the difference in the number of positive pulses and negative pulses within a certain period of time (that is, within a certain time window, illustrated by a dotted box in Figure 2).
  • the density of negative pulses refers to the difference in the number of negative pulses and positive pulses within a certain period of time (that is, within a certain time window).
  • Air pulse density refers to the difference in quantity between positive and negative pulses of multiple air pulses within a certain period of time, and the quantity difference is an absolute value.
  • the width of the time window may be about one-thousandth of 20 kHz, which is close to the period of the highest frequency of audible sound.
  • the width of the time window can also be other lengths, and this is not strictly limited in the embodiments of the present application.
  • a single time window typically includes multiple air pulses.
  • the sound pressure level of the audible sound changes with the change of the air pulse density of the second sound wave, that is, the amplitude of the audible sound is adjusted by the air pulse density of the second sound wave, and the frequency change of the audible sound is adjusted by the air pulse density of the second sound wave. Changes in the amplitude of the audible sound are produced, and therefore the frequency of the audible sound can be adjusted by adjusting the air pulse density of the second sound wave.
  • FIG. 3 is a schematic diagram 2 of the sound-generating principle of the sound-generating device 100 shown in FIG. 1 .
  • the density of the positive pulse signal or the negative pulse signal of the corresponding target air pulse signal is larger; in the second sound wave correspondingly formed by the air pulse generating component 30, the density of the air pulse is higher.
  • the sound pressure level of the audible sound changes with the change of the air pulse density of the second sound wave.
  • the greater the air pulse density of the second sound wave the higher the sound pressure level of the audible sound.
  • the smaller the air pulse density the lower the sound pressure level of the audible sound.
  • the method of adjusting the air pulse density includes but is not limited to: adjusting the ratio of positive pulses and negative pulses, and/or adjusting the number of positive pulses, and/or adjusting the number of negative pulses within a certain period of time.
  • Adjusting the ratio of positive pulses to negative pulses includes adjusting the ratio of positive pulses to negative pulses, or adjusting the ratio of positive pulses to the total number of air pulses, or adjusting the ratio of negative pulses to the total number of air pulses. For example, within a certain period (such as the first period), the greater the difference between the number of positive pulses and negative pulses, the higher the audible sound pressure level; the smaller the difference between the number of positive pulses and negative pulses, the higher the audible sound pressure level.
  • the situation where the difference between the number of positive pulses and negative pulses is large includes that the number of positive pulses is significantly larger than the number of negative pulses, or is significantly smaller than the number of negative pulses.
  • the sound pressure levels of the positive pulse P1 and the negative pulse P-1 among the plurality of air pulses of the second sound wave are the same, that is, the amplitudes are the same.
  • the sound pressure level of audible sound is adjusted by adjusting the air pulse density.
  • the sound pressure level adjustment of the audible sound can also be realized by adjusting the air pulse density and the sound pressure level of the air pulse at the same time.
  • the adjustable range of the audible sound pressure level is wider, and the sound-generating device has a wider applicable range and usage scenarios.
  • the second sound wave of the sound-generating device 100 is an ultrasonic wave, and the pulse rate of the second sound wave may be higher than 20 kHz.
  • the pulse rate of the second sound wave since the pulse rate of the second sound wave is higher than the highest frequency of audible sound, the multiple air pulses of the second sound wave can be more The waveform of the audible sound is well fitted, so that the sound pressure level of the audible sound is high and the distortion is small.
  • the frequency of the audible sound is mid-low frequency (20Hz-2000Hz)
  • the pulse rate of the second sound wave has a large multiple difference with the frequency of the audible sound, and the second sound wave can form a sound with high sound pressure level and low distortion. Listen.
  • the second sound wave of the sound-generating device 100 may also be an audible sound wave (less than 20 kHz), and the pulse rate of the second sound wave is a certain multiple of the frequency of the audible sound that is expected to be formed.
  • the pulse rate of the second sound wave can be in the range of 10kHz to 20kHz, so that the sound pressure level of the audible sound formed by the second sound wave is higher. , the distortion is smaller.
  • the sound-generating device 100 no longer uses a traditional speaker structure, but emits a second sound wave including multiple air pulses to form audible sound, and at the same time, it is achieved by controlling the air pulse density of the second sound wave. Amplitude adjustment and frequency adjustment of audible sound to achieve audio playback.
  • the plurality of air pulses of the second sound wave are realized by the vibration action of the vibrating member of the air pulse generating assembly 30. The frequency of the audible sound is lower than the pulse rate of the second sound wave, so the frequency of the audible sound is lower than the vibration of the vibrating member. frequency.
  • the displacement required for the vibrating member to vibrate at the pulse rate of the second sound wave is smaller. Since the sound-generating device 100 generates an audible sound by emitting the second sound wave, the displacement of the vibrating member of the air pulse generating assembly 30 is small. Furthermore, the sound-generating device 100 can adjust the amplitude of the audible sound by adjusting the air pulse density of the second sound wave. The sound pressure level adjustment of the audible sound does not need to rely on the displacement or surface area of the vibrating member. Therefore, the sound-generating device 100 generates sound through air pulses.
  • the small displacement vibration of the vibrating component of the component 30 and the higher air pulse density of the second sound wave can obtain audible sound with a high sound pressure level.
  • the low-frequency frequency response of the sound-generating device 100 does not have or basically does not have drop characteristics.
  • the low-frequency drop of the sound-generating device 100 is significantly lower than 12 dB, and the sound-generating device 100 can have a high low-frequency sound pressure level in a small size.
  • the small-volume sound-generating device 100 has wider applicability in scenes with space requirements.
  • the second sound wave emitted by the sound-generating device 100 as an ultrasonic wave, such as a modulated ultrasonic wave, as an example, a partial structure and a partial working principle of the sound-generating device 100 will be described.
  • FIG. 4 is a schematic structural diagram of the air pulse generating component 30 of the sound-generating device 100 shown in FIG. 1 in some embodiments.
  • the air pulse generating component 30 of the sound-generating device 100 includes a housing 1, a transducer, and a first valve 3.
  • the transducer is an ultrasonic transducer (ultrasonic transducer) 2 as an example.
  • the housing 1 has an inner cavity 11 and an opening 12 .
  • the opening 12 of the housing 1 communicates with the inner cavity 11 of the housing 1 and the external space of the housing 1 .
  • the housing 1 may include a top wall 13, a bottom wall 14, and a side wall 15.
  • the top wall 13 and the bottom wall 14 are arranged oppositely, and the side wall 15 is located between the top wall 13 and the bottom wall 14.
  • the top wall 13, the bottom wall 14 and the side walls 15 together define the inner cavity 11 .
  • the top wall 13 forms an opening 12 .
  • the ultrasonic transducer 2 is installed in the inner cavity 11 of the housing 1 and divides the inner cavity 11 of the housing 1 into a front cavity 111 and a rear cavity 112 .
  • the front cavity 111 is located between the rear cavity 112 and the opening 12 .
  • the rear cavity 112 is located between the bottom wall 14 and the ultrasonic transducer 2
  • the front cavity 111 is located between the ultrasonic transducer 2 and the opening 12 .
  • the first valve 3 is fixed to the housing 1 and covers the opening 12 of the housing 1 .
  • the housing 1 may not include the top wall 13, and one end of the side wall 15 is connected to the periphery of the bottom wall 14.
  • the bottom wall 14 and the side wall 15 jointly surround the inner cavity 11 of the housing 1.
  • the other end of the side wall 15 forms the opening 12 of the housing 1 .
  • the first valve 3 can adopt a piezoelectric structure.
  • the first valve 3 includes a piezoelectric piece. One end of the piezoelectric piece is a fixed end relative to the housing 1, and the other end is a movable end relative to the housing 1; the piezoelectric piece When electricity is applied, the piezoelectric sheet covers the opening 12 to achieve closing; when the piezoelectric sheet is energized, it deforms, and the movable end of the piezoelectric sheet is lifted, pressed down or displaced to open the opening 12 to achieve opening.
  • the first valve 3 may also have other piezoelectric structures, or the first valve 3 may also adopt other non-piezoelectric structures, which are not strictly limited in the embodiments of the present application.
  • the ultrasonic transducer 2 is used to generate the first sound wave driven by the first control signal.
  • the first valve 3 is used to open and close under the control of the second control signal; when the first valve 3 is opened, part of the first sound wave formed by the ultrasonic transducer 2 passes through the first valve 3 and forms a direction toward the sound-emitting device 100 air pulses emitted from the outside; when the first valve 3 is closed, the first sound wave formed by the ultrasonic transducer 2 is blocked by the first valve 3 and cannot propagate to the outside of the sound-generating device 100 .
  • the sound-generating device 100 selectively emits part of the first sound wave through the cooperation of the ultrasonic transducer 2 and the first valve 3 to form a plurality of air pulses, thereby forming a second sound wave.
  • the first sound wave is the basic sound wave of the second sound wave
  • the frequency of the first control signal is set to the ultrasonic frequency
  • the first sound wave is the initial ultrasonic wave, so that through the cooperation of the ultrasonic transducer 2 and the first valve 3, the selectivity
  • the ground emits part of the initial ultrasonic wave to form a plurality of air pulses, so that the second sound wave emitted by the air pulse generating component 30 is a modulated ultrasonic wave.
  • the first sound wave may be an audible sound wave or an ultrasonic wave.
  • the control circuit 20 is electrically connected to the ultrasonic transducer 2 and the first valve 3 .
  • the control circuit 20 is used to generate a first control signal and a second control signal.
  • the first control signal is used to drive the ultrasonic transducer 2 to vibrate.
  • the frequency of the first control signal may be greater than or equal to 20 kHz and the amplitude remains unchanged.
  • the vibrating component of the ultrasonic transducer 2 can vibrate reciprocally under the driving of the first control signal, and the vibration frequency of the vibrating component is greater than or equal to 20 kHz, that is, the vibration frequency of the vibrating component is the ultrasonic frequency, and the amplitude of the vibrating component remains unchanged.
  • the second control signal is used to control the switching state of the first valve 3 so that the sound-generating device 100 can selectively emit part of the initial ultrasonic wave to form a modulated ultrasonic wave including a plurality of air pulses, and the modulated ultrasonic wave forms an audible sound.
  • the frequency of the audible sound is lower than the vibration frequency of the vibrating member of the ultrasonic transducer 2 .
  • the first control signal may include one or more signals
  • the second control signal may include one or more signals
  • the first control signal and the second control signal may be different signals.
  • the types of air pulses that modulate ultrasonic waves may include positive pulse P1, zero pulse P0, and negative pulse P-1.
  • positive pulse P1 positive pulse P1
  • zero pulse P0 zero pulse P0
  • negative pulse P-1 negative pulse P-1
  • the first valve 3 opens, and the air in the front chamber 111 is pushed to the housing 1 In the external space, the ultrasonic transducer 2 generates a positive pulse P1; during the period when the vibrating member leaves the equilibrium position and moves downward to return to the equilibrium position, the first valve 3 opens, and the air in the external space of the housing 1 is sucked into In the front cavity 111, the ultrasonic transducer 2 generates negative pulse P-1.
  • the first valve 3 is closed, and the ultrasonic transducer 2 generates a zero pulse P0.
  • the zero pulse P0 can also be understood as not generating an air pulse with an amplitude.
  • the upward movement of the vibrating member means that the vibrating member moves in a direction closer to the first valve 3
  • the downward movement of the vibrating member means that the vibrating member moves in a direction away from the first valve 3 .
  • FIG. 5 is a schematic diagram of the sound-generating device 100 shown in FIG. 1 in some usage states.
  • FIG. 6 is a schematic diagram of the internal structure of the air pulse generating assembly 30 shown in FIG. 4 in some usage states.
  • FIG. 7 is a schematic diagram of the internal structure of the air pulse generating assembly 30 shown in FIG. 4 in other usage states.
  • the usage state of the air pulse generating assembly 30 in FIGS. 6 and 7 corresponds to the usage state shown in FIG. 5 .
  • the waveform of the first control signal may be a sinusoidal waveform; the phase in the period from 0 to T/2 is positive, and is used to drive the vibrating member of the ultrasonic transducer 2 away from the equilibrium position upward. After the movement, it returns to the equilibrium position; in the period from T/2 to T, the phase is negative, and the vibrating member used to drive the ultrasonic transducer 2 moves downward from the equilibrium position and then returns to the equilibrium position.
  • the waveform of the second control signal may be a square wave; the level in the corresponding period from 0 to T/2 is 1, which is used to control the opening of the first valve 3; the level in the corresponding period from T/2 to T is 0, used to control the first valve 3 to close.
  • FIG. 8 is a schematic diagram of the sound-generating device 100 shown in FIG. 1 in other usage states.
  • FIG. 9 is a schematic diagram of the internal structure of the air pulse generating assembly 30 shown in FIG. 4 in some usage states.
  • FIG. 10 is a schematic diagram of the internal structure of the air pulse generating assembly 30 shown in FIG. 4 in other usage states.
  • the usage state of the air pulse generating assembly 30 in FIGS. 9 and 10 corresponds to the usage state shown in FIG. 8 .
  • the waveform of the first control signal may be a sinusoidal waveform; the phase in the period from 0 to T/2 is positive, and is used to drive the vibrating member of the ultrasonic transducer 2 away from the equilibrium position upward. After the movement, it returns to the equilibrium position; in the period from T/2 to T, the phase is negative, and the vibrating member used to drive the ultrasonic transducer 2 moves downward from the equilibrium position and then returns to the equilibrium position.
  • the waveform of the second control signal may be a square wave; the level in the corresponding period from 0 to T/2 is 0, which is used to control the first valve 3 to close; the level in the corresponding period from T/2 to T is 1, used to control the opening of the first valve 3.
  • the vibrating member of the ultrasonic transducer 2 leaves the equilibrium position and moves upward and then returns to the equilibrium position.
  • the first valve 3 is closed, and the ultrasonic transducer 2 forms a The air pulse is zero pulse P0.
  • the vibrating component of the ultrasonic transducer 2 leaves the equilibrium position and moves downward and then returns to the equilibrium position.
  • the first valve 3 opens, and the outside of the housing 1 The air in the space enters the front chamber 111, and the air pulse formed by the ultrasonic transducer 2 is a negative pulse P-1.
  • the first valve 3 is opened, the air in the front chamber 111 is pushed to the external space of the housing 1, and the ultrasonic transducer 2 generates positive energy.
  • Pulse P1 during the period of downward movement of the vibrating member, the first valve 3 is opened, the air in the external space of the housing 1 is sucked into the front chamber 111, and the ultrasonic transducer 2 generates a negative pulse P-1.
  • the first valve 3 is closed, and the ultrasonic transducer 2 generates zero pulse P0.
  • FIG. 11 is a schematic diagram of the sound-generating device 100 shown in FIG. 1 in other usage states.
  • the waveform of the first control signal may be a sinusoidal waveform; the phase in the period from 0 to T/2 is positive, and is used to drive the vibrating member of the ultrasonic transducer 2 to move upward from the equilibrium position and then return to the equilibrium position. ; In the period from T/2 to T, the phase is negative, and the vibrating member used to drive the ultrasonic transducer 2 moves downward from the equilibrium position and then returns to the equilibrium position.
  • the waveform of the second control signal may be a square wave; in the corresponding period from 0 to T/2, and in the corresponding period when the vibrating member moves upward, the level is 1, used to control the opening of the first valve 3, and the ultrasonic transducer 2 forms a positive pulse P1; in the corresponding period from 0 to T/2, and in the corresponding period when the vibrating member moves downward, the level is 0, which is used to control the first valve 3 to close, and the ultrasonic transducer 2 forms a zero pulse P0; in the corresponding period from T/2 to T, and in the corresponding period when the vibrating member moves downward, the level is 1, which is used to control the opening of the first valve 3 and the ultrasonic transducer 2 to form a negative pulse P-1; In the corresponding period from T/2 to T, and in the corresponding period when the vibrating member moves upward, the level is 0, which is used to control the first valve 3 to close, and the ultrasonic transducer 2 forms a zero pulse P0.
  • the above-mentioned first implementation manner or the second implementation manner may be used alone, or the above-mentioned first implementation manner and the second implementation manner may be used in combination. , the embodiments of this application do not strictly limit this.
  • the waveform of the first control signal is exemplified as a sine wave
  • the waveforms of the air pulse and the second control signal are exemplified as a square wave.
  • the waveform of the first control signal can also be a triangular wave. , square wave or other waveforms
  • the waveforms of the air pulse and the second control signal can also be sine waves, triangular waves or other waveforms. in the following In the relevant description, for convenience of explanation, the waveform of the first control signal is still taken as a sine wave, and the waveforms of the air pulse and the second control signal are taken as a square wave.
  • the sound-generating device 100 can form modulated ultrasonic waves through various modulation rules.
  • the basic principle of the modulation rule is to convert the audio signal into a target air pulse signal according to the pulse density modulation algorithm, form a control signal according to the target air pulse signal, and the control signal controls the air pulse generation component 30 to form a modulated ultrasonic wave including multiple air pulses, and the modulated ultrasonic wave An audible sound is formed, and the audible sound corresponds to the audio signal.
  • the target air pulse signal carries relevant information about the target air pulse, and the target air pulse is converted into a sound wave by pulse density modulation, which corresponds to the audio signal.
  • the multiple air pulses that modulate the ultrasonic waves formed are difficult to completely correspond to the target air pulses, and there may be a small amount of distortion. Therefore, the modulation rules are used to make the multiple air pulses that modulate the ultrasonic waves as much as possible. Just get close to the target air pulse.
  • the first modulation rule is the first modulation rule:
  • FIG. 12 is a schematic diagram of the first modulation rule of the sound-generating device 100 shown in FIG. 1 .
  • the positive pulse P1, negative pulse P-1 and zero pulse P0 of the modulated ultrasonic wave adopt the first implementation method mentioned above.
  • the frequency of the first control signal is one-half the pulse rate of the target air pulse.
  • the pulse rate of the target air pulse refers to the maximum frequency at which the target air pulse type can be selected.
  • the pulse type can be switched (for example, the positive pulse P1 is switched to the negative pulse P -1 or zero pulse P0), you can also keep the pulse type unchanged.
  • the first half cycle of a single cycle of the first control signal is defined as the positive half cycle, which corresponds to the period in which the vibrating member of the air pulse generating assembly 30 first moves upward from the equilibrium position and then returns to the equilibrium position.
  • the period of the first control signal is
  • the second half cycle in is defined as the negative half cycle, corresponding to the period in which the vibrating member of the air pulse generating assembly 30 first moves downward from the equilibrium position and then returns to the equilibrium position.
  • the frequency of the second control signal may be twice the frequency of the first control signal.
  • the frequency of the second control signal refers to the maximum frequency at which the content of the second control signal can be set or assigned.
  • the frequency of the second control signal corresponds to the maximum frequency at which the first valve 3 can perform switching state selection.
  • the switch state selection includes switching or maintaining the open state, switching or maintaining the closed state. When the second control signal is at a high level, it controls the first valve 3 to open, and when it is at a low level, it controls the first valve 3 to close.
  • the second control signal When the target air pulse is a positive pulse P1 and the first control signal is in the positive half cycle, the second control signal is set to high level to form a positive pulse P1 in the corresponding period of the modulated ultrasonic wave; when the target air pulse is a negative pulse P- 1.
  • the first control signal When the first control signal is in the negative half cycle, the second control signal is set to a high level to form a negative pulse P-1 in the corresponding period of the modulated ultrasonic wave.
  • the target air pulse When the target air pulse is the zero pulse P0, the second control signal is set to a low level to form the zero pulse P0 in the corresponding period of the modulated ultrasonic wave.
  • the target air pulse can be realized in the corresponding period of the modulated ultrasonic wave, so that the final audible sound can correspond to the audio signal.
  • the second control signal is set to low level to form a zero pulse P0 in the corresponding period of the modulated ultrasonic wave.
  • the distortion degree is low and the distortion ratio is low, so the degree of distortion of the final audible sound relative to the audio signal can be reduced.
  • FIG. 13 is a schematic diagram of the second modulation rule of the sound-generating device 100 shown in FIG. 1 .
  • the positive pulse P1, negative pulse P-1 and zero pulse P0 of the modulated ultrasonic wave adopt the first implementation method mentioned above.
  • the frequency of the first control signal is the same as the pulse rate of the target air pulse.
  • the first half cycle of a single cycle of the first control signal is defined as the positive half cycle, which corresponds to the period in which the vibrating member of the air pulse generating assembly 30 first moves upward from the equilibrium position and then returns to the equilibrium position.
  • the period of the first control signal is
  • the second half cycle in is defined as the negative half cycle, corresponding to the period in which the vibrating member of the air pulse generating assembly 30 first moves downward from the equilibrium position and then returns to the equilibrium position.
  • the frequency of the second control signal may be twice the frequency of the first control signal.
  • the second control signal When the second control signal is at a high level, it controls the first valve 3 to open, and when it is at a low level, it controls the first valve 3 to close.
  • the second control signal When the target air pulse is a positive pulse P1 and the first control signal is in the positive half cycle, the second control signal is set to high level to form a positive pulse P1 in the corresponding period of the modulated ultrasonic wave; when the target air pulse is a negative pulse P- 1.
  • the first control signal When the first control signal is in the negative half cycle, the second control signal is set to high level to form a negative pulse P-1 in the corresponding period of the modulated ultrasonic wave.
  • the target air pulse can be realized in the corresponding period of the modulated ultrasonic wave, so that the final audible sound can correspond to the audio signal.
  • the first valve can be accurately controlled according to the type of the target air pulse. 3 is opened or closed in the positive half-cycle and negative half-cycle of the first control signal, so that the modulated ultrasonic wave finally obtains an air pulse that matches the target air pulse, and the distortion of the modulated ultrasonic wave is low.
  • the frequency of the first control signal is easily limited by the material, structure, size and other factors of the vibrating component of the air pulse generating assembly 30.
  • the pulse rate of the target air pulse of the first modulation rule is twice the pulse rate of the target air pulse of the second modulation rule.
  • the first modulation rule can use high pulse rate target air pulses, so that even if there is a small amount of distortion in the modulated ultrasonic wave, it can still achieve high-quality conversion of the audio signal, making the audible sound higher in sound quality and sound pressure level.
  • the pulse rate of the target air pulse is low in the second modulation rule, due to the small distortion of the modulated ultrasonic wave, it can also achieve high-quality conversion of the audio signal, resulting in higher audible sound quality and higher sound pressure level.
  • FIG. 14 is a schematic diagram of the third modulation rule of the sound-generating device 100 shown in FIG. 1 .
  • the positive pulse P1, negative pulse P-1 and zero pulse P0 of the modulated ultrasonic wave adopt the second implementation method mentioned above.
  • the frequency of the first control signal is one-half the pulse rate of the target air pulse.
  • the first half cycle of a single cycle of the first control signal is defined as the positive half cycle, which corresponds to the period in which the vibrating member of the air pulse generating assembly 30 first moves upward from the equilibrium position and then returns to the equilibrium position.
  • the period of the first control signal is
  • the second half cycle in is defined as the negative half cycle, corresponding to the period in which the vibrating member of the air pulse generating assembly 30 first moves downward from the equilibrium position and then returns to the equilibrium position. That is, during the rising phase in a single cycle of the first control signal, the vibration member moves upward, and during the falling phase in a single cycle of the first control signal, the vibration member moves downward.
  • the frequency of the second control signal may be four times the frequency of the first control signal.
  • the second control signal When the second control signal is at a high level, it controls the first valve 3 to open, and when it is at a low level, it controls the first valve 3 to close.
  • the second control signal When the target air pulse is a positive pulse P1 and the first control signal is in the rising stage, the second control signal is set to a high level to form a positive pulse P1 in the corresponding period of the modulated ultrasonic wave; when the target air pulse is a negative pulse P-1 , when the first control signal is in the falling stage, the second control signal is set to a high level to form a negative pulse P-1 in the corresponding period of the modulated ultrasonic wave.
  • the second control signal when the target air pulse is a positive pulse P1 and the first control signal is in the falling stage, the second control signal is set to a low level to form a zero pulse P0 in the corresponding period of the modulated ultrasonic wave; when the target air pulse is a negative pulse P -1, when the first control signal is in the rising stage of the negative half cycle, the second control signal is set to a low level to form a zero pulse P0 in the corresponding period of the modulated ultrasonic wave.
  • the second control signal since the half cycle of the first control signal corresponds to a target air pulse, the second control signal
  • the frequency of the control signal is four times the frequency of the first control signal. Therefore, the opening or closing of the first valve 3 in the rising stage or falling stage of the first control signal can be accurately controlled according to the type of the target air pulse, so that the ultrasonic wave can be modulated. Finally, an air pulse matching the target air pulse is obtained, and the audible sound formed by the modulated ultrasonic wave can correspond to the audio signal, and the distortion of the audible sound is low.
  • FIG. 15 is a schematic diagram of the fourth modulation rule of the sound-generating device 100 shown in FIG. 1 .
  • the positive pulse P1, negative pulse P-1 and zero pulse P0 of the modulated ultrasonic wave adopt the second implementation method mentioned above.
  • the frequency of the first control signal is less than one-half of the pulse rate of the target air pulse.
  • the frequency of the first control signal is one-third of the pulse rate of the target air pulse.
  • a single period of the first control signal includes a rising phase and a falling phase.
  • the rising phase corresponds to the phase in which the vibrating member of the air pulse generating assembly 30 moves upward.
  • the falling phase corresponds to the phase in which the vibrating member of the air pulse generating assembly 30 moves downward.
  • the frequency of the second control signal is significantly greater than the frequency of the first control signal and can be flexibly set according to the target air pulse and the first control signal to minimize the degree of distortion of the modulated ultrasonic wave relative to the target air pulse.
  • the first valve 3 is controlled to open, and when it is at a low level, the first valve 3 is controlled to close.
  • the target air pulse is a positive pulse P1 and the first control signal is in the rising stage
  • the second control signal is set to a high level to form a positive pulse P1 in the corresponding period of the modulated ultrasonic wave; when the target air pulse is a negative pulse P- 1.
  • the second control signal When the first control signal is in the falling stage, the second control signal is set to a high level to form a negative pulse P-1 in the corresponding period of the modulated ultrasonic wave.
  • the second control signal when the target air pulse is a positive pulse P1 and the first control signal is in the falling stage, the second control signal is set to a low level to form a zero pulse P0 in the corresponding period of the modulated ultrasonic wave; when the target air pulse is a negative pulse P -1, when the first control signal is in the rising stage of the negative half cycle, the second control signal is set to a low level to form a zero pulse P0 in the corresponding period of the modulated ultrasonic wave.
  • the above-mentioned first to fourth modulation rules are part of the modulation rules of the sound-generating device 100.
  • the sound-generating device 100 may also have other modulation rules, which are not strictly limited by the embodiments of the present application.
  • the frequency of the second control signal may be greater than or equal to twice the frequency of the first control signal, so that the first valve 3 can achieve at least one reciprocating vibration of the vibrating member of the air pulse sound-generating assembly.
  • the sound-generating device 100 can smoothly send out the positive pulse P1, and/or the negative pulse P-1, and/or the zero pulse P0.
  • the modulated ultrasonic wave can realize the frequency adjustment and adjustment of the audible sound through the adjustment of the air pulse density. Amplitude adjustment.
  • the frequency of the second control signal is lower than twice the frequency of the first control signal, the selection frequency of the switching state of the first valve 3 is too low, and the opening time or closing time of the first valve 3 exceeds the air
  • the half-vibration cycle of the vibrating component of the pulse sound-generating component can easily cause the modulated ultrasonic wave to generate undesirable energy offsets of positive pulse P1 and negative pulse P-1, which will cause problems such as energy waste and sound pressure level reduction.
  • the pulse rate of the plurality of air pulses that modulate the ultrasonic wave is the same as the frequency of the second control signal, and the pulse rate of the plurality of air pulses that modulate the ultrasonic wave is the maximum frequency at which the type of air pulse can be selected.
  • the pulse type can be switched (for example, positive pulse P1 is switched to negative pulse P-1 or zero pulse P0), or the pulse type can be kept unchanged, such as the above-mentioned first to fourth modulation rules.
  • the frequency of the second control signal may be equal to twice the frequency of the first control signal, and the maximum density of the positive pulse P1 of the modulated ultrasonic wave is the same as the frequency of the first control signal.
  • the maximum density of the negative pulse P-1 of the ultrasonic wave is the same as the frequency of the first control signal, such as the above-mentioned first modulation rule and the second modulation rule.
  • the amplitude of the first control signal remains unchanged to drive the vibration of the vibrating component of the ultrasonic transducer 2.
  • the amplitude remains unchanged and an initial ultrasonic wave with constant amplitude is generated.
  • the initial ultrasonic wave is a single-frequency ultrasonic wave
  • the working frequency band of the vibrating component of the ultrasonic transducer 2 is a narrow frequency band.
  • the vibrating component only needs to have a high response at a single point, so the ultrasonic transducer 2 can better utilize the vibration.
  • the resonant frequency of the component achieves response, thereby improving the energy conversion efficiency and conducive to increasing the sound pressure level.
  • the amplitude of the first control signal may also change.
  • the change in the amplitude of the first control signal causes the sound pressure level of the air pulse to change.
  • the sound-generating device 100 can adjust the sound pressure level of the second sound wave in the air.
  • the pulse density and the sound pressure level of the air pulse realize the sound pressure level adjustment of the audible sound, and the sound pressure level adjustment range of the audible sound is wider. For example, in the case of increasing the air pulse density of the second sound wave, the sound pressure level of at least part of the air pulses is simultaneously increased to further increase the sound pressure level of the audible sound.
  • the sound-generating device 100 may have a variety of implementation structures based on the above-mentioned sound-generating methods and modulation rules. Examples are given below.
  • the inner cavity 11 of the housing 1 of the air pulse generating assembly 30 is divided into a front cavity 111 and a rear cavity 112 by the ultrasonic transducer 2 .
  • the sound-generating device 100 can separate the inner cavity 11 of the housing 1 through the ultrasonic transducer 2 alone to form a front cavity 111 and a rear cavity 112 .
  • the sound-generating device 100 can also cooperate with other structures (such as part of the structure of the housing 1) through the ultrasonic transducer 2 to jointly separate the inner cavity 11 of the housing 1 to form a front cavity 111 and a rear cavity. 112.
  • the embodiments of this application do not strictly limit this.
  • the air pulse generating component 30 has a communication hole 16.
  • the communication hole 16 is used to communicate the front cavity 111 and the rear cavity 112 to achieve air pressure balance between the front cavity 111 and the rear cavity 112, so that the ultrasonic transducer 2 can vibrate smoothly, thereby An initial ultrasonic wave with small distortion is formed driven by the first control signal.
  • the communication hole 16 may be provided in the ultrasonic transducer 2 .
  • the minimum width of the connecting hole 16 is greater than the thickness of the viscous layer d ⁇ , and the thickness of the viscous layer f is the frequency of the first control signal.
  • the minimum width of the communication hole 16 refers to the size at the narrowest position of a single communication hole 16 .
  • the communication hole 16 realizes the acoustic communication between the front cavity 111 and the rear cavity 112 , so that the air in the front cavity 111 and the air in the rear cavity 112 can reciprocate in the ultrasonic transducer 2 During the vibration process, mutual flow is smoothly achieved through the communication hole 16 to better achieve air pressure balance between the front chamber 111 and the rear chamber 112 .
  • the communication holes 16 can have various shapes, as long as they can achieve acoustic communication.
  • the shapes can include but are not limited to round holes, square holes, elongated holes, slits, etc., which are not strictly limited in the embodiments of the present application.
  • the number of communication holes 16 may be one or more, which is not strictly limited in the embodiment of the present application.
  • acoustic connectivity means that sound can pass through.
  • the housing 1 is provided with a rear leakage hole 17 , which connects the rear cavity 112 of the housing 1 and the external space of the housing 1 to achieve air pressure balance between the rear cavity 112 and the external space of the housing 1 .
  • the shape of the rear leakage hole 17 can be various, as long as it can achieve ventilation.
  • the shape can include but is not limited to round holes, square holes, elongated holes, slits, etc., and the embodiments of this application are not strictly limited.
  • the number of rear leak holes 17 may be one or more, which is not strictly limited in the embodiment of the present application.
  • the sound-generating device 100 may also be provided with a first damping mesh 18 .
  • the first damping mesh 18 may be fixed to the housing 1 by bonding or other methods, and cover the rear leak hole 17 .
  • the first damping mesh 18 is breathable, so that the air pulse generating assembly 30 can still achieve air pressure balance between the rear cavity 112 and the external space of the housing 1 through the rear leak hole 17 .
  • the first damping mesh 18 can achieve acoustic isolation between the rear cavity 112 and the external space of the housing 1, so that the sound waves in the rear cavity 112 will not leak to the external space of the housing 1.
  • breathability means that the media on both sides of the interface can be exchanged, and acoustic isolation means that sound cannot penetrate.
  • the quantity, shape, etc. of the first damping mesh 18 are adapted to the rear leak hole 17 .
  • the sound-generating device 100 may not be provided with the first damping mesh 18 , which is not strictly limited by the embodiments of this application.
  • FIG. 16 is a schematic diagram of the internal structure of the air pulse generating assembly 30 shown in FIG. 4 .
  • the ultrasonic transducer 2 includes a vibration member 21 and a support member 22, and the vibration member 21 is fixed to the support member 22.
  • the vibration member 21 is used to reciprocate driven by the first control signal to form an initial ultrasonic wave.
  • the support member 22 is fixedly connected to the housing 1 so that the ultrasonic transducer 2 is installed in the inner cavity 11 of the housing 1 .
  • the front cavity 111 is located on the side of the vibrating member 21 facing the first valve 3
  • the rear cavity 112 is located on the side of the vibrating member 21 facing away from the front cavity 111 .
  • the support member 22 may be fixedly connected to the side wall 15 of the housing 1 .
  • the first valve 3 can be fixedly connected to the top wall 13 of the housing 1 .
  • the front cavity 111 is located between the first valve 3 and the top wall 13 and the vibrating member 21 .
  • the rear cavity 112 is located between the vibrating member 21 and the bottom wall 14 .
  • the communication hole 16 may be provided on the support member 22 .
  • the communication hole 16 may also be formed in the gap between the vibration member 21 and the support member 22 .
  • the communication hole 16 can also have other implementation structures, which are not strictly limited in the embodiments of the present application.
  • the air pulse generating component 30 when the initial ultrasonic wave is transmitted in the front cavity 111, it is easy to cause problems such as sound wave reflection and sound wave cancellation of opposite phases, resulting in distortion, large energy loss and other problems in the modulated ultrasonic wave finally emitted by the air pulse generating component 30. .
  • the distance H1 between the first valve 3 and the vibrating member 21 is less than ⁇ /2, where ⁇ is the wavelength of the initial ultrasonic wave.
  • the distance between the first valve 3 and the vibrating member 21 will affect the phase delay of the initial ultrasonic wave.
  • the initial ultrasonic wave can be reduced.
  • the loss of ultrasonic waves during transmission in the front cavity 111 improves the problems of easy distortion and large energy loss of modulated ultrasonic waves, improves the energy conversion efficiency of the air pulse generating assembly 30, and is beneficial to increasing the sound pressure level of audible sound.
  • the vibrating member 21 when the vibrating member 21 vibrates back and forth, the vibrating member 21 will also generate another ultrasonic wave in the rear cavity 112. This ultrasonic wave will propagate and reflect in the rear cavity 112, and part of the ultrasonic wave will be transmitted to the front through the communication hole 16.
  • the cavity 111 is superimposed with the initial ultrasonic wave, and this part of the ultrasonic wave is called the back cavity reflected sound wave in the following text.
  • the height H2 of the rear cavity 112 is in the range of M* ⁇ + ⁇ /4- ⁇ /8 to M* ⁇ + ⁇ /4+ ⁇ /8, ⁇ is the initial value
  • M is a natural number.
  • the height H2 of the rear cavity 112 may be the distance between the vibration member 21 and the bottom wall 14 of the housing 1 .
  • the phase of the sound wave reflected from the back cavity is the same as or close to the phase of the initial ultrasonic wave. The superposition of the sound wave reflected from the back cavity and the initial ultrasonic wave produces an enhancement effect, which is beneficial to increasing the sound pressure level of the audible sound.
  • the height H2 of the rear cavity 112 may be in the range of M* ⁇ + ⁇ /4- ⁇ /9 to M* ⁇ + ⁇ /4+ ⁇ /9, or in the range of M* ⁇ + ⁇ /4- ⁇ /10 to the range of M* ⁇ + ⁇ /4+ ⁇ /10 to obtain better sound wave superposition effect and higher audible sound pressure level.
  • the height H2 of the rear cavity 112 is outside the range of M* ⁇ + ⁇ /2- ⁇ /8 to M* ⁇ + ⁇ /2+ ⁇ /8 to avoid
  • the superposition of the back cavity reflected sound wave and the initial ultrasonic wave creates a cancellation problem to reduce the distortion of the modulated ultrasonic wave.
  • the height H2 of the rear cavity 112 should be as far as possible outside the range of M* ⁇ + ⁇ /2- ⁇ /9 to M* ⁇ + ⁇ /2+ ⁇ /9, or within the range of M* ⁇ + ⁇ /2- ⁇ / Outside the range of 10 to M* ⁇ + ⁇ /2+ ⁇ /10.
  • FIG. 17 is a schematic diagram of the internal structure of the air pulse generating assembly 30 shown in FIG. 1 in other embodiments.
  • the air pulse generating assembly 30 of this embodiment may include most of the technical features of the air pulse generating assembly 30 of the previous embodiment. The differences between the two are mainly described below, and the same content between the two will not be described again.
  • the air pulse generating component 30 of the sound generating device 100 is also provided with a sound absorbing member 19 , and the sound absorbing member 19 is installed in the rear cavity 112 .
  • the sound-absorbing member 19 may be sound-absorbing cotton, a local resonance sound-absorbing structure, or other sound-absorbing structures.
  • the arrangement of the sound absorbing member 19 can weaken or eliminate the ultrasonic waves emitted by the vibrating member 21 to the rear cavity 112, thereby weakening or eliminating the reflected sound waves from the rear cavity, and reducing the influence of the reflected sound waves from the rear cavity on the modulated ultrasonic waves, thereby increasing the sound pressure level of audible sound.
  • pass Simulation calculation shows that after adding the sound absorbing member 19 to the air pulse generating assembly 30, the audible sound pressure level is increased by more than 3dB, and the distortion is reduced.
  • the sound absorbing member 19 may be a plate-like structure or a layered structure.
  • the sound absorbing member 19 may be fixed to the bottom wall 14 of the housing 1 , and the sound absorbing member 19 covers part or all of the bottom wall 14 .
  • the sound absorbing member 19 can also be fixed on the area of the side wall 15 of the housing 1 facing the rear cavity 112 to increase the sound absorbing area of the sound absorbing member 19 .
  • the sound-absorbing member 19 can also be a relatively three-dimensional structural member that can be fixed in the rear cavity 112 .
  • a certain spacing is formed between the sound absorbing member 19 and the vibrating member 21 , and the space corresponding to the spacing is used as the vibration space of the vibrating member 21 to prevent the sound absorbing member 19 from interfering with the vibration of the vibrating member 21 .
  • the height design of the rear cavity 112 is more flexible, and the height of the rear cavity 112 can be the same as the previous embodiment (for example, the embodiment corresponding to Figure 16) Same or different.
  • the air pulse generating assembly 30 disposes the sound absorbing member 19 in the rear cavity 112 to weaken or eliminate the reflected sound wave in the rear cavity, thereby reducing the distortion of the modulated ultrasonic wave, and can make the height of the rear cavity 112 less than ⁇ /4, thereby reducing the air
  • the overall height of the pulse generating component 30 is beneficial to miniaturization of the air pulse generating component 30 and the sound-generating device 100 .
  • the height of the back cavity 112 can be within 1 mm, and a sound absorbing member is provided in the back cavity 112.
  • the height of the back cavity 112 can be, for example, 0.95mm, 0.8mm, 0.87mm, etc., so that the air pulse generating assembly 30 and the sound generating device can 100 has a small overall height and volume, and the distortion of modulated ultrasonic waves is small.
  • the frequency of the first control signal may be around 40kHz.
  • FIG. 18 is a schematic diagram of the internal structure of the air pulse generating assembly 30 shown in FIG. 1 in other embodiments.
  • FIG. 19 is a schematic diagram of the internal structure of the air pulse generating assembly 30 shown in FIG. 18 .
  • the air pulse generating assembly 30 of this embodiment can include most of the technical features of the air pulse generating assembly 30 of the previous embodiment.
  • the main difference between the two is that in this embodiment, the communication hole 16 of the air pulse generating assembly 30 is provided in the shell. Body 1.
  • the processing difficulty of the communication hole 16 is relatively low, and the processing difficulty and cost of the ultrasonic transducer 2 can be reduced.
  • the air pulse generating component 30 has multiple communication holes 16 , some of the communication holes 16 may be formed in the ultrasonic transducer 2 and some of the communication holes 16 may be formed in the housing 1 .
  • FIG. 20 is a schematic diagram of the internal structure of the air pulse generating assembly 30 shown in FIG. 1 in other embodiments.
  • the air pulse generating assembly 30 of this embodiment may include most of the technical features of the air pulse generating assembly 30 of the previous embodiment. The differences between the two are mainly described below, and the same content between the two will not be described again.
  • the air pulse generating assembly 30 further includes a second valve 4 , and the second valve 4 may be provided on the ultrasonic transducer 2 .
  • the second valve 4 When the second valve 4 is opened, it connects the front chamber 111 and the rear chamber 112 to balance the pressures of the front chamber 111 and the rear chamber 112; when it is closed, the second valve 4 isolates the front chamber 111 and the rear chamber 112.
  • the communication hole 16 is replaced by the selectively conductable second valve 4 to more flexibly adjust the communication between the front chamber 111 and the rear chamber 112 .
  • the second valve 4 can adopt a piezoelectric structure.
  • the second valve 4 includes a piezoelectric piece. One end of the piezoelectric piece is a fixed end relative to the housing 1, and the other end is a movable end relative to the housing 1; the piezoelectric piece When electricity is applied, the piezoelectric piece separates the front cavity 111 and the rear cavity 112 to achieve closure; when the piezoelectric piece is energized, it deforms, and the movable end of the piezoelectric piece is lifted, pressed down or displaced, etc., to connect The front cavity 111 and the rear cavity 112 are opened.
  • the second valve 4 may also have other piezoelectric structures, or the second valve 4 may also adopt other non-piezoelectric structures, which are not strictly limited in the embodiments of the present application.
  • control circuit 20 (see Figure 1) of the sound-generating device 100 is also electrically connected to the second valve 4.
  • the control circuit 20 is also used to generate a third control signal.
  • the third control signal is used to control the switching state of the second valve 4. .
  • the second valve 4 can be opened according to any rules to achieve pressure balance between the front chamber 111 and the rear chamber 112 .
  • the setting of the switching time, switching duration and switching frequency of the switching state of the second valve 4 are relatively flexible, and the third control signal is less restricted by the first control signal and the second control signal.
  • the opening frequency of the second valve 4 should not be too low.
  • the third control signal is used to control the opening period of the second valve 4 to be less than or equal to twenty times the period of the first control signal. That is, during the twenty cycles of vibration of the vibrating component of the ultrasonic transducer 2, the second valve 4 is opened at least once to connect the front chamber 111 and the rear chamber 112 and balance the pressures of the front chamber 111 and the rear chamber 112.
  • the minimum width of the conduction cross-section when the second valve 4 is opened is greater than the thickness of the viscous layer d ⁇ , and the thickness of the viscous layer f is the frequency of the first control signal.
  • the minimum width of a conductive section refers to the dimension at the narrowest position of the conductive section.
  • the second valve 4 When the second valve 4 is always open, the second valve 4 can also be regarded as a communication hole.
  • a conductive space such as a through hole, a gap or a gap can be provided on the ultrasonic transducer 2, and the second valve 4 covers the conductive space to connect the second valve 4 to the ultrasonic transducer 2.
  • the second valve 4 When the second valve 4 is opened, the front chamber 111 and the rear chamber 112 are connected.
  • the second valve 4 is closed, the front chamber 111 and the rear chamber 112 are separated.
  • FIG. 21 is a schematic diagram of the internal structure of the air pulse generating assembly 30 shown in FIG. 1 in other embodiments.
  • the air pulse generating assembly 30 of this embodiment can include most of the technical features of the air pulse generating assembly 30 of the previous embodiments (for example, the embodiment corresponding to FIG. 20 ).
  • the main difference between the two is: in this embodiment, the air pulse generating assembly
  • the second valve 4 of 30 is provided in the housing 1. When the second valve 4 is provided in the housing 1, the processing difficulty and cost of the ultrasonic transducer 2 can be reduced.
  • the air pulse generating component 30 of this embodiment reference can be made to the relevant descriptions of the previous embodiments and will not be described again here.
  • FIG. 22 is a schematic diagram of the internal structure of the air pulse generating assembly 30 shown in FIG. 1 in other embodiments.
  • the air pulse generating assembly 30 of this embodiment may include most of the technical features of the air pulse generating assembly 30 of the previous embodiment. The differences between the two are mainly described below, and the same content between the two will not be described again.
  • the inner cavity 11 of the housing 1 of the air pulse generating assembly 30 is divided into a front cavity 111 and a rear cavity 112 by the ultrasonic transducer 2.
  • the front cavity 111 and the rear cavity 112 are not connected to each other. That is to say, during the operation of the air pulse generating assembly 30, the front chamber 111 and the rear chamber 112 always remain isolated and disconnected.
  • the housing 1 is provided with a front leakage hole 110 , which communicates the front cavity 111 of the housing 1 with the external space of the housing 1 .
  • the front leakage hole 110 through the arrangement of the front leakage hole 110, the pressure balance between the front cavity 111 of the housing 1 and the external space of the housing 1 is maintained, so that the vibration component 21 of the ultrasonic transducer 2 can vibrate smoothly to form sound waves.
  • the front leak hole 110 may be provided on the top wall 13 and/or the side wall 15 of the housing 1, which is not strictly limited in the embodiment of the present application.
  • the shape of the front leakage hole 110 can be various, as long as it can achieve ventilation, and the shape can include but is not limited to a round shape. Holes, square holes, long holes, slits, etc. are not strictly limited in the embodiments of this application.
  • the number of front leakage holes 110 may be one or more, which is not strictly limited in the embodiment of the present application.
  • the sound-generating device 100 may also be provided with a second damping mesh 120 .
  • the second damping mesh 120 may be fixed to the housing 1 by bonding or other methods, and cover the front leakage hole 110 .
  • the second damping mesh 120 is breathable, so that the air pulse generating assembly 30 can still achieve air pressure balance between the front chamber 111 and the external space of the housing 1 through the front leak hole 110 .
  • the second damping mesh 120 can achieve acoustic isolation between the front cavity 111 and the external space of the housing 1, so that the sound waves in the front cavity 111 will not leak to the external space of the housing 1.
  • the number, shape, etc. of the second damping mesh 120 are adapted to the front leakage holes 110 .
  • the sound-generating device 100 may not be provided with the second damping mesh 120 , which is not strictly limited by the embodiments of this application.
  • the above-described sound-generating device 100 of the present application can be used to form audible sounds of medium and low frequencies (20Hz-2000Hz), or can also be used to form audible sounds of the full frequency range (20Hz-20000Hz).
  • the sound-generating device 100 can be used alone, or in combination with multiple sound-generating devices 100 , or in combination with other speakers of the same type or different types, such as piezoelectric speakers and moving coil speakers.
  • the sound-generating device 100 of the present application can realize mid- to low-frequency audible sounds, and a loudspeaker such as a piezoelectric speaker or a moving coil speaker can realize high-frequency audible sounds.
  • the frequency of audible sound depends on the air pulse density that modulates the ultrasonic wave, and the air pulse density is based on the initial ultrasonic wave.
  • the ultrasonic transducer 2 vibrates back and forth driven by the first control signal to generate the initial ultrasonic wave. Therefore, The frequency realization of the audible sound is closely related to the frequency of the first control signal.
  • the frequency of the first control signal is less than 400 kHz, so that the modulated ultrasonic wave forms an audible sound with a frequency in the range of 20 Hz to 2 kHz. In other embodiments, the frequency of the first control signal is greater than or equal to 400 kHz, so that the modulated ultrasonic wave forms an audible sound with a frequency in the range of 20 Hz to 20 kHz. In the above embodiment, the frequency design of the first control signal can make the distortion of the modulated ultrasonic wave lower and the sound pressure level of the audible sound higher.
  • the ultrasonic transducer 2 since the ultrasonic transducer 2 is used for reciprocating vibration to generate an initial ultrasonic wave, and the initial ultrasonic wave is a single-frequency ultrasonic wave, the resonant frequency of the vibrating component of the ultrasonic transducer 2 is set to be consistent with the desired The frequency of the initial ultrasonic wave formed is the same or close to that of the first control signal, which can improve the response of the vibrating component of the ultrasonic transducer 2 to the first control signal, and has a high energy utilization rate, which is beneficial to improving Audible sound pressure level.
  • the frequency of the first control signal is the same as the resonant frequency of the vibrating component of the ultrasonic transducer 2, so that the initial ultrasonic wave has a high matching degree with the first control signal, which is beneficial to increasing the sound pressure level that can be improved.
  • the high Q-value characteristics of the piezoelectric structure can be used for driving to improve the energy conversion efficiency, and the energy utilization rate of the ultrasonic transducer 2 is high.
  • the Q value is called the quality factor
  • a high Q value means low sound wave energy loss (the attenuation rate is proportional to the square of the frequency).
  • the ultrasonic transducer 2 can have a variety of basic implementation structures. Examples will be given below. The structure of the ultrasonic transducer 2 below can be applied to any of the air pulse generating components 30 described above.
  • Figure 23 is a schematic structural diagram of the ultrasonic transducer 2 provided by the embodiment of the present application in some embodiments.
  • the ultrasonic transducer 2 may be a piezoelectric ultrasonic transducer.
  • the ultrasonic transducer 2 includes a support member 22 and a vibration member 21.
  • the vibration member 21 includes a diaphragm 211 and a piezoelectric sheet 212.
  • the periphery of the diaphragm 211 is fixed to the support member 22, and the piezoelectric sheet 212 is fixed to the middle of the diaphragm 211.
  • the piezoelectric sheet 212 includes a piezoelectric material layer.
  • the ultrasonic transducer Transducer 2 is a piezoelectric single crystal ultrasonic transducer.
  • the piezoelectric material layer may use piezoelectric materials such as lead zirconate titanate piezoelectric ceramics (PZT for short).
  • the piezoelectric sheet 212 can be bonded to the diaphragm 211 through the adhesive layer 213 .
  • the piezoelectric piece 212 can be located on the upper surface or the lower surface of the diaphragm 211, which is not strictly limited in the embodiment of the present application.
  • the diaphragm 211 can be made of aluminum or other materials. In this embodiment, due to the high Q value characteristics of the piezoelectric sheet 212, the ultrasonic transducer 2 has high energy conversion efficiency.
  • the resonant frequency of the vibrating component 21 of the ultrasonic transducer 2 can be adjusted so that the resonant frequency is within a desired frequency range.
  • the resonant frequency of the vibrating member 21 is designed to be 40 kHz, so as to be suitable for the sound-generating device 100 that needs to generate audible sounds of medium and low frequencies.
  • the piezoelectric sheet 212 adopts a disc-shaped structure.
  • the piezoelectric material is PZT-5H.
  • the polarization direction is the thickness direction of the piezoelectric sheet 212.
  • a voltage is applied to the upper and lower surfaces of the piezoelectric sheet 212.
  • the piezoelectric sheet 212 The radius is 4mm and the thickness is 0.8mm.
  • the diaphragm 211 is made of aluminum and has a thickness of 0.2mm. At this time, the resonance frequency of the vibrating member 21 is 40 kHz or close to 40 kHz.
  • the ultrasonic transducer 2 of this embodiment is mainly used to emit initial ultrasonic waves with a frequency less than 400 kHz.
  • the vibrating member 21 can be improved.
  • the resonant frequency so that the resonant frequency matches the frequency of the desired initial ultrasonic wave.
  • Specific solutions can be designed based on actual needs and will not be described in detail here.
  • the ultrasonic transducer 2 of this embodiment can also be used to emit initial ultrasonic waves with a frequency above 400 kHz.
  • the ultrasonic transducer 2 may also include a sound wave directing member 23.
  • the sound wave directing member 23 is located above the vibrating member 21.
  • the sound wave directing member 23 is used to control the initial vibration generated by the ultrasonic transducer 2.
  • the radiation direction of ultrasonic waves is limited to improve the radiation efficiency of the initial ultrasonic waves, which is beneficial to increasing the sound pressure level of audible sound.
  • the sound wave directing member 23 may include a cone-shaped emitting surface 231.
  • the cone-shaped emitting surface 231 can narrow the directivity of the initial ultrasonic wave to about 60°, which significantly improves the radiation efficiency of the initial ultrasonic wave.
  • FIG. 24 is a schematic structural diagram of the ultrasonic transducer 2 provided by the embodiment of the present application in other embodiments.
  • the ultrasonic transducer 2 of this embodiment may include most of the technical features of the ultrasonic transducer 2 of the previous embodiment. The differences between the two are mainly described below, and the same content between the two will not be described again.
  • the piezoelectric sheet 212 of the vibration component 21 of the ultrasonic transducer 2 may include a plurality of stacked piezoelectric material layers, and the polarization directions of at least two of the plurality of piezoelectric material layers are Opposite or the applied voltage is in the opposite direction.
  • the ultrasonic transducer 2 is a piezoelectric double crystal ultrasonic transducer.
  • the piezoelectric sheet 212 includes two piezoelectric material layers.
  • the piezoelectric sheet 212 includes a first piezoelectric material layer 2121 and a second piezoelectric material layer 2122.
  • the polarization directions of the first piezoelectric material layer 2121 and the second piezoelectric material layer 2122 are opposite, or the applied voltage directions of the first piezoelectric material layer 2121 and the second piezoelectric material layer 2122 are opposite.
  • the piezoelectric sheet 212 may also include three or more piezoelectric material layers.
  • FIG. 25 is a schematic structural diagram of the ultrasonic transducer 2 provided by the embodiment of the present application in other embodiments.
  • the ultrasonic transducer 2 of this embodiment may include most of the technical features of the ultrasonic transducer 2 of the previous embodiment. The differences between the two are mainly described below, and the same content between the two will not be described again.
  • the ultrasonic transducer 2 includes a support member 22 and a vibration member 21 .
  • the vibration member 21 is a piezoelectric sheet, and the piezoelectric sheet is fixed to the support member 22 .
  • the piezoelectric sheet may include one or more piezoelectric material layers, and the piezoelectric material layer may be made of piezoelectric materials such as lead zirconate titanate piezoelectric ceramics. When the piezoelectric sheet includes multiple piezoelectric material layers, the multiple piezoelectric material layers are stacked.
  • the ultrasonic transducer 2 can use a thicker piezoelectric ceramic block as the piezoelectric sheet, and the piezoelectric sheet directly forms the vibration member 21 without the need for a diaphragm, thereby having a higher resonance frequency.
  • the resonant frequency of the vibrating component 21 of the ultrasonic transducer 2 in this embodiment may be greater than or equal to 400 kHz.
  • the resonant frequency may be designed to be 500 kHz, 600 kHz, etc.
  • Figure 26 shows the ultrasonic transducer 2 provided by the embodiment of the present application in other embodiments.
  • 27 is a partial structural schematic diagram of the ultrasonic transducer 2 shown in FIG. 26 .
  • the ultrasonic transducer 2 of this embodiment may include most of the technical features of the ultrasonic transducer 2 of the previous embodiment. The differences between the two are mainly described below, and the same content between the two will not be described again.
  • the ultrasonic transducer 2 includes a support 22 and a vibration member 21.
  • the vibration member 21 includes a diaphragm 211 and a plurality of piezoelectric sheets 212.
  • the periphery of the diaphragm 211 is fixed to the support 22, and the plurality of piezoelectric sheets 212. 212 is fixed on the middle part of the diaphragm 211.
  • the piezoelectric sheet 212 may include one or more piezoelectric material layers, and the piezoelectric sheet 212 may be a single crystal piezoelectric sheet or a bicrystal piezoelectric sheet.
  • the resonance frequencies of the plurality of piezoelectric sheets 212 are the same.
  • the plurality of piezoelectric sheets 212 are arranged at intervals from each other, for example, in an array or other arrangements.
  • the ultrasonic transducer 2 can be used in scenarios with large vibration areas. Compared with the solution where only one piezoelectric piece is provided on the vibrating member 21 , since the resonance frequency of the piezoelectric piece 212 will decrease as the area of the piezoelectric piece 212 increases, it is difficult to achieve high-frequency ultrasonic radiation.
  • each piezoelectric sheet 212 can have a higher resonance frequency, and the multiple piezoelectric sheets 212 arranged on the plane where the diaphragm 211 is located vibrate together, which is also beneficial to The sound pressure level of the initial ultrasonic wave is increased, so that the sound pressure level of the audible sound formed by the sound-generating device 100 is higher.
  • the resonant frequency of the vibrating component 21 of the ultrasonic transducer 2 in this embodiment can be greater than or equal to 400 kHz, which is beneficial to the sound-generating device 100 achieving full-frequency sound generation. In some other embodiments, the resonant frequency of the vibrating member 21 of the ultrasonic transducer 2 may also be less than 400 kHz.
  • FIG. 28 is a schematic structural diagram of the ultrasonic transducer 2 provided by the embodiment of the present application in other embodiments.
  • FIG. 29 is a partial structural schematic diagram of the ultrasonic transducer 2 shown in FIG. 28 .
  • the ultrasonic transducer 2 of this embodiment may include most of the technical features of the ultrasonic transducer 2 of the previous embodiment. The differences between the two are mainly described below, and the same content between the two will not be described again.
  • the ultrasonic transducer 2 includes a support member 22 and a vibration member 21 , and the vibration member 21 is fixed to the support member 22 .
  • the vibration component 21 includes a base material 213 and a plurality of piezoelectric elements 214.
  • the base material 213 can be made of polymer materials such as epoxy resin.
  • the piezoelectric elements 214 can be made of piezoelectric materials such as lead zirconate titanate piezoelectric ceramics.
  • the component 214 is embedded in the base material 213 .
  • the base material 213 may have a generally thin plate structure, and the plurality of piezoelectric elements 214 are arranged along the plate surface direction of the base material 213 , and the plate surface direction of the base material 213 is perpendicular to the thickness direction of the base material 213 .
  • the plurality of piezoelectric elements 214 are arranged at intervals, that is, a gap is formed between two adjacent piezoelectric elements 214 .
  • the plurality of piezoelectric elements 214 may be arranged in an array or other arrangements.
  • FIG. 29 illustrates the structure of a partial region of the vibrating member 21 , and only one of the piezoelectric elements 214 is numbered in FIG. 29 .
  • the vibration member 21 adopts a piezoelectric composite structure. Compared with a pure piezoelectric ceramic structure, the structural strength and reliability are improved, and the resonance frequency of the vibration member 21 is higher.
  • the resonance frequency of the vibration member 21 in this embodiment may be greater than or equal to 400 kHz.
  • the resonant frequency of the vibrating member 21 of the ultrasonic transducer 2 may also be less than 400 kHz.
  • the piezoelectric composite structure of the vibration member 21 in this embodiment is conducive to the preparation of a large-area piezoelectric element array.
  • the resonance frequencies of the multiple piezoelectric elements 214 in the piezoelectric element array are the same.
  • the vibration member 21 can be configured with a larger number of piezoelectric elements.
  • the piezoelectric element 214 can increase the sound pressure level of the initial ultrasonic wave formed by the vibrating member 21, thereby increasing the sound pressure level of the modulated ultrasonic wave formed by the sound-generating device 100, so that the sound pressure level of the audible sound is higher.
  • the ultrasonic transducer 2 may also be a polyvinylidene difluoride (PVDF) piezoelectric film ultrasonic transducer.
  • the vibrating component of the ultrasonic transducer 2 is a polyvinylidene fluoride piezoelectric film.
  • the polyvinylidene fluoride piezoelectric film can achieve ultrasonic emission on a curved surface or a plane through a simple constraint method, and the frequency is relatively high, and the vibration component is The resonant frequency is generally in the range of 1MHz to 100MHz. At this time, the vibration member of the ultrasonic transducer 2 can relatively easily obtain a resonance frequency of 400 kHz or more.
  • the vibration of the ultrasonic transducer 2 The resonant frequency of the moving component 21 may also have other resonant frequencies, for example, less than 400 kHz.
  • the ultrasonic transducer 2 may also be a micromachined ultrasonic transducer (Micromachined Ultrasonic Transducer, MUT).
  • MUT Micromachined Ultrasonic Transducer
  • the ultrasonic transducer 2 may be a capacitive micromechanical ultrasonic transducer (cMUT) or a piezoelectric micromechanical ultrasonic transducer (pMUT).
  • the resonance frequency of the vibrating component of the ultrasonic transducer 2 in this embodiment is usually relatively high, for example, it may be greater than or equal to 400 kHz.
  • the resonant frequency of the vibrating member 21 of the ultrasonic transducer 2 may also be less than 400 kHz.
  • capacitive micro-machined ultrasonic transducers and piezoelectric micro-machined ultrasonic transducers are miniature ultrasonic transducers manufactured using MEMS (Micro-Electro-Mechanical System) technology.
  • Capacitive micromachined ultrasonic transducers generally form a cavity on a silicon substrate. The top surface of the cavity is made of diaphragm material, such as nitride, etc., and signals are applied through electrode materials to achieve ultrasonic emission.
  • Piezoelectric micromachined ultrasonic transducers are generally made by superimposing piezoelectric materials on a silicon substrate, such as lead zirconate titanate piezoelectric ceramics.
  • ultrasonic waves are generated due to the inverse piezoelectric effect.
  • These two types of ultrasonic transducers 2 based on MEMS technology can be easily implemented in array design, which is beneficial to increasing the sound pressure level of the initial ultrasonic wave formed by the vibrating component, thereby increasing the sound pressure level of the modulated ultrasonic wave formed by the sound-generating device 100, making it possible to The sound pressure level for listening is higher.
  • the ultrasonic transducer 2 may also have other implementation structures, which are not strictly limited in the embodiments of the present application.
  • the air pulse generating assembly 30 in the previous embodiment is described by taking an example of including an ultrasonic transducer 2 .
  • the air pulse generating assembly 30 may also include multiple ultrasonic transducers 2 , as illustrated below.
  • FIG. 30 is a schematic structural diagram of the air pulse generating assembly 30 shown in FIG. 1 in other embodiments.
  • FIG. 31 is a partial structural schematic diagram of the air pulse generating assembly 30 shown in FIG. 30 .
  • the ultrasonic transducer 2 of this embodiment may include most of the technical features of the ultrasonic transducer 2 of the previous embodiment. The differences between the two are mainly described below, and the same content between the two will not be described again.
  • the air pulse generating component 30 includes multiple ultrasonic transducers 2, and the multiple ultrasonic transducers 2 are installed in the inner cavity 11 of the housing 1, and are located between the front cavity 111 and the rear cavity 112.
  • the resonance frequencies of the vibrating members of the plurality of ultrasonic transducers 2 are the same.
  • the structure of the ultrasonic transducer 2 can adopt any of the structures described above.
  • the plurality of ultrasonic transducers 2 may be arranged in an array or in other arrangements.
  • the air pulse generating component 30 can be applied in usage scenarios with large volume and large lateral space.
  • the air pulse generating assembly 30 is configured with multiple ultrasonic transducers 2.
  • the vibrating component of each ultrasonic transducer 2 can have a higher resonance frequency, and at the same time, the sound pressure level of the initial ultrasonic wave can be increased, so that the sound can be emitted.
  • the audible sound produced by the device 100 has a higher sound pressure level.
  • the resonant frequency of the vibrating component of the ultrasonic transducer 2 of this embodiment may be greater than or equal to 400 kHz, which is beneficial to the sound-generating device 100 achieving full-frequency sound generation. In some other embodiments, the resonant frequency of the vibrating component of the ultrasonic transducer 2 may also be less than 400 kHz.

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Abstract

本申请公开了一种发声装置和电子设备。发声装置包括壳体、换能器、第一阀门及控制电路，壳体具有内腔和开口，换能器安装于壳体的内腔，且将壳体的内腔分隔为前腔和后腔，前腔位于后腔与开口之间，第一阀门固定于壳体且覆盖壳体的开口；控制电路电连接换能器和第一阀门，控制电路用于产生第一控制信号和第二控制信号，第一控制信号被配置为驱动换能器振动，第二控制信号被配置为控制第一阀门的开关状态，以使发声装置发出多个空气脉冲，形成可听声；其中，可听声的频率低于换能器的振动频率，多个空气脉冲包括正脉冲和负脉冲，可听声的声压级随正脉冲与负脉冲的比例变化或数量变化而变化。上述发声装置体积较小，且低频声压级较高。

Description

发声装置和电子设备
本申请要求于2022年04月14日提交中国专利局、申请号为202210394548.3、申请名称为“发声装置、电子设备及发声方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中；本申请还要求于2022年07月12日提交中国专利局、申请号为202210812781.9、申请名称为“发声装置和电子设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及音频技术领域，尤其涉及一种发声装置和电子设备。
背景技术
微型扬声器在当前众多消费电子产品中应用广泛，为广大消费者提供了音频娱乐，增强了音频体验。
在声波传播的物理学教导上，在人类可听频率范围(一般为20Hz至20kHz)内，传统扬声器驱动振膜振动所产生的声压可表示为其中Sd为振膜的表面积，A为振膜的加速度。也就是说，声压P正比于振膜的表面积Sd与振膜的加速度A的乘积。此外，振膜的位移D与振膜的加速度A的关系可表示为A＝-w2D，其中w为声波的角频率。传统扬声器驱动振膜振动所引起的空气推动量V＝D*Sd。因此，声压可重写为即声压与空气推动量V成正比，与角频率w的平方呈正比。
举例而言，在传统的电动力学扬声器中，其线圈和磁铁用于产生振膜的驱动力，1kHz的声音是由其振膜于一定的表面积以1kHz振动所产生的，而100Hz的声音也是由振膜以100Hz振动所产生的。若两个频率的声压级(soundpressure level，SPL)相同，则100Hz所需的空气推动量为1kHz所需空气推动量的100倍。换句话说，若两个频率的空气推动量相同，则100Hz声压级比1kHz声压级小40dB。
传统的电动力学扬声器中，振膜在共振频率以前的低频区间内位移一致，空气推动量一致，因此，随着观测频率增加一倍，声压级增加12dB。换句话说，随着观测频率降低一倍，声压级降低12dB。举例而言，若一传统扬声器在某一测试条件下，400Hz的声压级为90dB，则在相同测试条件下，200Hz声压级为78dB。因此传统扬声器有明显的低频下潜特性，低频跌落达到-12dB，斜率大，导致扬声器的低频声压级不足。
为了增加扬声器的低频声压级，提升音频体验，需要增加振膜的位移D或者振膜的表面积A，而增加振膜的表面积A会增加扬声器的横向空间，增加振膜的位移D会增加扬声器的纵向空间。这两种方式均会增加扬声器的空间需求，导致扬声器体积过大，无法堆叠到体积较小的电子产品中。因此，扬声器如何在有限体积下，提升低频声压级是业界亟待解决的问题。
发明内容
本申请提供一种发声装置及应用该发声装置的电子设备，发声装置的体积较小，且形成 的可听声的低频声压级较高。
第一方面，本申请提供一种发声装置，包括壳体、换能器、第一阀门及控制电路，壳体具有内腔和开口，壳体的开口连通壳体的内腔与壳体的外部空间，换能器安装于壳体的内腔，且将壳体的内腔分隔为前腔和后腔，前腔位于后腔与开口之间，第一阀门固定于壳体且覆盖壳体的开口。
控制电路电连接换能器和第一阀门，控制电路用于产生第一控制信号和第二控制信号，第一控制信号被配置为驱动换能器的振动构件振动，第二控制信号被配置为控制第一阀门的开关状态，以使发声装置发出多个空气脉冲，形成可听声。其中，可听声的频率低于换能器的振动构件的振动频率，多个空气脉冲包括正脉冲和负脉冲，可听声的声压级随正脉冲和负脉冲的比例变化或数量变化而变化。
其中，多个空气脉冲形成第二声波，第二声波的多个空气脉冲挤压或舒张空气，从而引起空气的密度变化。其中，第二声波在空气中的平均密度变化与可听声的平均密度变化一致，因此第二声波在空气中形成可听声，可听声可传播至人耳。其中，第二声波的脉冲率高于期望形成的可听声的频率，也即，第二声波在可听声的单个周期内包括多个空气脉冲，这部分空气脉冲能够拟合出可听声的单个周期的波形。
在本申请中，由于发声装置不再采用传统扬声器结构，而是发出包括多个空气脉冲的第二声波，形成可听声，同时通过控制第二声波的空气脉冲密度实现可听声的振幅调节和频率调节，从而实现音频播放。
此外，第二声波的多个空气脉冲由空气脉冲产生组件的振动构件的振动动作实现，可听声的频率低于第二声波的脉冲率，因此可听声的频率低于振动构件的振动频率。此时，当需要形成具有相同声压级的可听声时，相较于振动构件以可听声的频率进行振动所需的位移，振动构件以第二声波的脉冲率进行振动所需的位移更小。由于发声装置通过发出第二声波，以形成可听声，因此空气脉冲产生组件的振动构件的位移小。并且，发声装置通过调节第二声波的空气脉冲密度即可实现可听声的振幅调节，可听声的声压级调节无需依赖于振动构件的位移或表面积，因此发声装置通过空气脉冲产生组件的振动构件的小位移振动，和第二声波的较高的空气脉冲密度，即可获得高声压级的可听声，发声装置的低频频响不存在或基本不存在跌落特性，发声装置的低频跌落明显低于12dB，发声装置能够在小体积的情况下，具有较高的低频声压级。小体积的发声装置在有空间要求的场景中具有更广泛的适用性。
其中，可听声的声压级与空气脉冲密度正相关。例如，在某一时段内，正脉冲的密度越大，代表该时段的可听声的声压为正，且幅值越大，反之，负脉冲的密度越大，代表该时段的可听声的声压为负，且幅值越大，正脉冲和负脉冲连续转换的时段对应可听声的幅值小，幅值为绝对值。其中，正脉冲的密度是指在某一时段内，正脉冲与负脉冲的数量差。负脉冲的密度是指在某一时段内，负脉冲与正脉冲的数量差。空气脉冲密度是指在某一时段内，多个空气脉冲的正脉冲与负脉冲的数量差值，数量差值为绝对值。
此外，由于可听声的声压级随第二声波的空气脉冲密度的变化而变化，也即可听声的幅值由第二声波的空气脉冲密度调节，而可听声的频率变化由可听声的幅值变化产生，因此可听声的频率可以通过调整第二声波的空气脉冲密度实现调节。
在本申请中，可听声的声压级随第二声波的空气脉冲密度的变化而变化。第二声波的空气脉冲密度越大，则可听声的声压级越高，空气脉冲密度越小，则可听声的声压级越低。
其中，空气脉冲密度的调节方式包括但不限于：在某一时段内，调节正脉冲和负脉冲的 比例，和/或调节正脉冲的数量，和/或调节负脉冲的数量。调节正脉冲和负脉冲的比例，包括调节正脉冲与负脉冲的比例，或者调节正脉冲与总空气脉冲数量的比例，或者调节负脉冲与总空气脉冲数量的比例。例如，在某一时段(例如第一时段)内，正脉冲与负脉冲的数量差值越大，可听声的声压级越高；正脉冲与负脉冲的数量差值越小，可听声的声压级越低。正脉冲与负脉冲的数量差值大的情况包括正脉冲的数量明显大于负脉冲的数量，或者明显小于负脉冲的数量。再例如，在某一时段(例如第一时段)内，正脉冲与负脉冲的比例越远离1，可听声的声压级越高，正脉冲与负脉冲的比例越靠近1，可听声的声压级越低。
一些可能的实现方式中，多个空气脉冲的正脉冲和负脉冲的声压级相同。此时，可听声的声压级调节通过调整空气脉冲密度实现。通过设置第一控制信号的振幅不变，驱动换能器的振动构件的振幅不变，从而产生振幅不变的正脉冲和负脉冲。此时，换能器的振动构件的工作频段为窄频段，振动构件只需要在单点具有较高的响应，因此换能器能够更好地利用振动构件的共振频率实现响应，从而提高能量转化效率，有利于提高声压级。
在其他一些实现方式中，可听声的声压级调节也可以既调整空气脉冲密度，同时结合调整空气脉冲的声压级实现。此时，可听声的声压级的可调范围更大，发声装置的适用范围和使用场景更广。
一些可能的实现方式中，发声装置的第二声波为超声波，第二声波的脉冲率可以高于20kHz。此时，由于第二声波的脉冲率高于可听声的最高频率，因此第二声波的多个空气脉冲能够更好地拟合出可听声的波形，使得可听声的声压级高，且失真小。例如，当可听声的频率为中低频(20Hz-2000Hz)时，第二声波的脉冲率与可听声的频率的倍数差较大，第二声波能够形成声压级高、失真小的可听声。
一些可能的实现方式中，发声装置的第二声波也可以为可听声波(低于20kHz)，第二声波的脉冲率与期望形成的可听声的频率具有一定倍数。例如，期望形成的可听声的频率为中低频(20Hz-2000Hz)时，第二声波的脉冲率可以在10kHz至20kHz的范围内，使得第二声波形成的可听声的声压级较高，失真较小。
一些可能的实现方式中，换能器用于在第一控制信号驱动下产生第一声波。第一阀门用于在第二控制信号控制下实现打开和关闭；第一阀门打开时，换能器形成的第一声波的部分声波通过第一阀门，形成向发声装置的外部发出的空气脉冲；第一阀门关闭时，换能器形成的第一声波被第一阀门阻隔，不能传播到发声装置的外部。发声装置通过换能器与第一阀门的配合，选择性地发出部分第一声波，形成多个空气脉冲，从而形成第二声波。
其中，第一声波为第二声波的基础声波，设置第一控制信号的频率为超声频率，第一声波为初始超声波，以通过换能器与第一阀门的配合，选择性地发出部分初始超声波，形成多个空气脉冲，使得空气脉冲产生组件发出的第二声波为调制超声波。在其他一些实施例中，当第二声波为可听声波时，第一声波可以为可听声波或者超声波。
一些可能的实现方式中，第一控制信号的频率大于或等于20kHz且振幅不变。其中，换能器的振动构件能够在第一控制信号的驱动下往复振动，振动构件的振动频率大于或等于20kHz，也即振动构件的振动频率为超声频率，振动构件的振幅不变，形成振幅不变的初始超声波。
一些可能的实现方式中，第二控制信号的频率大于或等于两倍的第一控制信号的频率。此时，第一阀门能够在空气脉冲发声组件的振动构件的一次往复振动中实现至少两次开关状态的选择，发声装置能够顺利发出正脉冲、和/或负脉冲、和/或零脉冲，第二声波能够通过空气脉冲密度的调节实现可听声的频率调节及振幅调节。
一些可能的实现方式中，第二控制信号的频率等于两倍的第一控制信号的频率，正脉冲的最大密度与第一控制信号的频率相同。
一些可能的实现方式中，发声装置还包括第二阀门，第二阀门设于换能器或壳体，第二阀门打开时连通前腔与后腔。第二阀门打开时形成前腔与后腔之间的声学连通。
一些可能的实现方式中，控制电路电连接第二阀门，控制电路还用于产生第三控制信号。在换能器的空气脉冲产生组件的振动构件的往复振动过程中，第二阀门可以依照任意规则打开，以实现前腔与后腔的压力平衡。第二阀门的开关时刻、开关时长及开关状态的切换频率的设置均较为灵活，第三控制信号受到第一控制信号及第二控制信号的限制较少。
第三控制信号用于控制第二阀门的打开周期小于或等于二十倍的第一控制信号的周期，以保证空气脉冲产生组件的前腔与后腔的压力状态能够满足振动构件顺利振动的基本需要，降低振动构件振动的失真程度。
其中，第二阀门打开时的导通截面的最小宽度大于粘滞层厚度dμ，粘滞层厚度f为第一控制信号的频率。导通截面的最小宽度是指导通截面的最窄的位置处的尺寸。在本实施例中，第二阀门导通时形成前腔与后腔之间的声学连通。
一些可能的实现方式中，换能器或壳体设有连通孔，连通孔连通前腔与后腔。连通孔用以实现前腔和后腔的气压平衡，使得换能器能够顺畅振动，从而在第一控制信号的驱动下形成失真程度小的第一声波。
其中，连通孔的最小宽度大于粘滞层厚度dμ，粘滞层厚度f为第一控制信号的频率。连通孔的最小宽度是指单个连通孔的最窄的位置处的尺寸。
一些可能的实现方式中，前腔与后腔互不连通。在空气脉冲产生组件的工作过程中，前腔与后腔始终保持隔断、不连通的状态。壳体设有前泄孔，前泄孔连通壳体的前腔与壳体的外部空间。通过前泄孔的设置，使得壳体的前腔与壳体的外部空间保持压力平衡，使得换能器的振动构件能够顺利振动，形成声波。
其中，发声装置还可以设有第二阻尼网布，第二阻尼网布可以通过粘接等方式固定于壳体，且覆盖前泄孔。第二阻尼网布透气，使得空气脉冲产生组件仍可以通过前泄孔实现前腔与壳体的外部空间的气压平衡。此外，第二阻尼网布能够实现前腔与壳体的外部空间之间的声学隔离，使得前腔中的声波不会泄露至壳体的外部空间。第二阻尼网布的数量、形状等与前泄孔相适配。在其他一些实施例中，发声装置也可以不设置第二阻尼网布。
一些可能的实现方式中，壳体设有后泄孔，后泄孔连通壳体的后腔与壳体的外部空间。后泄孔用以实现后腔与壳体的外部空间的气压平衡。
其中，发声装置还可以设有第一阻尼网布，第一阻尼网布可以通过粘接等方式固定于壳体，且覆盖后泄孔。第一阻尼网布透气，使得空气脉冲产生组件仍可以通过后泄孔实现后腔与壳体的外部空间的气压平衡。此外，第一阻尼网布能够实现后腔与壳体的外部空间之间的声学隔离，使得后腔中的声波不会泄露至壳体的外部空间。其中，透气是指界面两侧的介质可以交换，声学隔离是指声音无法穿透。第一阻尼网布的数量、形状等与后泄孔相适配。在其他一些实现方式中，发声装置也可以不设置第一阻尼网布。
一些可能的实现方式中，第一控制信号的频率小于400kHz，以使发声装置形成频率在20Hz至2kHz范围内的可听声。此时，第一控制信号的频率设计能够使第二声波的失 真程度较低，可听声的声压级较高。
一些可能的实现方式中，第一控制信号的频率大于或等于400kHz，以使发声装置形成频率在20Hz至20kHz范围内的可听声。此时，第一控制信号的频率设计能够使第二声波的失真程度较低，可听声的声压级较高。
一些可能的实现方式中，由于换能器用于往复振动以产生第一声波，第一声波为单频声波，因此通过将换能器的振动构件的共振频率设置为，与期望形成的第一声波的频率相同或相近，也即与第一控制信号的频率相同或相近，可以提高换能器的振动构件对第一控制信号的响应程度，能量利用率高，有利于提高可听声的声压级。其中，当换能器的振动构件采用压电结构时，可以利用压电结构的高Q值的特性做驱动，以提高能量转换效率，换能器的能量利用率高。其中，Q值叫做品质因数，高Q值意味着低的声波能量损耗(其衰减率则与频率平方成正比)。
一些可能的实现方式中，换能器包括支撑件、振膜及压电片，振膜的周缘固定于支撑件，压电片固定于振膜的中部。压电片可以为单晶压电片或双晶压电片。其中，振膜和压电片形成的振动构件的共振频率小于400kHz。
一些可能的实现方式中，换能器包括支撑件和压电片，压电片固定于支撑件。压电片可以为单晶压电片或双晶压电片。其中，压电片的共振频率大于或等于400kHz。
一些可能的实现方式中，换能器包括支撑件、振膜及多个压电片，振膜的周缘固定于支撑件，多个压电片固定于振膜的中部，多个压电片的共振频率相同。其中，振膜及多个压电片形成的振动构件的共振频率大于或等于400kHz。
一些可能的实现方式中，换能器的振动构件包括基材和多个压电件，基材采用聚合物材料，多个压电件嵌设于基材内。其中，振动构件的共振频率大于或等于400kHz。
一些可能的实现方式中，换能器采用聚偏氟乙烯压电薄膜换能器、电容式微机械换能器或压电式微机械换能器。其中，换能器的振动构件的共振频率大于或等于400kHz。
一些可能的实现方式中，发声装置包括多个换能器，多个换能器均安装于壳体的内腔，且位于前腔与后腔之间。其中，多个换能器的振动构件的共振频率相同且均大于或等于400kHz。
一些可能的实现方式中，第一控制信号的频率与换能器的振动构件的共振频率相同，使得第一声波与第一控制信号的匹配度高，有利于提高可提升的声压级。
一些可能的实现方式中，换能器包括振动构件，振动构件用于在第一控制信号的驱动下往复运动，形成第一声波。第一声波可以为超声波或可听声波。
一些可能的实现方式中，在振动构件的垂直方向上，第一阀门与振动构件之间的距离小于λ/2，λ为第一声波的波长。在本实施例中，第一阀门与振动构件之间的距离会影响到第一声波的相位延迟，通过设置第一阀门与振动构件之间的距离小于λ/2，从而能够降低第一声波在前腔传输时的损耗，改善第二声波的容易出现失真、能量损耗大等问题，提高了空气脉冲产生组件的能量转换效率，有利于提高可听声的声压级。
一些可能的实现方式中，在振动构件的垂直方向上，后腔的高度在M*λ+λ/4-λ/8至M*λ+λ/4+λ/8的范围内，λ为第一声波的波长，M为自然数。在本实施例中，后腔反射声波的相位与第一声波的相位相同或相近，后腔反射声波与第一声波的叠加产生增强效果，从而有利于提高可听声的声压级。例如，后腔的高度H2可以在M*λ+λ/4-λ/9至M*λ+λ/4+λ/9的范围内，或者在M*λ+λ/4-λ/10至M*λ+λ/4+λ/10的范围内，以获得更佳的声波叠加效果，更高的可听声的声压级。
示例性的，在振动构件的垂直方向上，后腔的高度H2在M*λ+λ/2-λ/8至M*λ+λ/2+λ/8的范围之外，以避免后腔反射声波与第一声波的叠加产生抵消问题，以降低第二声波的失真。例如，后腔的高度H2尽量在M*λ+λ/2-λ/9至M*λ+λ/2+λ/9的范围之外，或者在M*λ+λ/2-λ/10至M*λ+λ/2+λ/10的范围之外。
一些可能的实现方式中，发声装置还设有吸音件，吸音件安装于后腔中。其中，吸音件可以是吸音棉、或者局域共振吸音结构、或者其他吸音类结构等。吸音件的设置可以减弱或消除振动构件向后腔发出的第一声波，从而减弱或消除后腔反射声波，降低后腔反射声波对第二声波的影响，以提高可听声的声压级。通过仿真计算，空气脉冲产生组件增加吸音件后，可听声的声压级提高了3dB以上，同时失真降低。
一些可能的实现方式中，在振动构件的垂直方向上，后腔的高度小于λ/4。此时，空气脉冲产生组件通过在后腔设置吸音件，以减弱或消除后腔反射声波，从而降低第二声波的失真，并且可以使后腔的高度小于λ/4，从而降低空气脉冲产生组件的整体高度，有利于空气脉冲产生组件及发声装置的小型化。
一些可能的实现方式中，发声装置还包括信号处理电路，信号处理电路用于依据脉冲密度调制算法将音频信号转为目标空气脉冲信号，控制电路用于依据目标空气脉冲信号，形成第一控制信号和第二控制信号。
其中，脉冲密度调制算法通过目标空气脉冲信号对应区域的密度表示音频信号的幅值。目标空气脉冲信号携带目标空气脉冲的相关信息，目标空气脉冲用于形成与音频信号对应的声波。目标空气脉冲信号可以包括正脉冲信号、零脉冲信号和负脉冲信号中的至少一种。正脉冲信号对应于目标空气脉冲中的正脉冲，负脉冲信号对应于目标空气脉冲中的负脉冲，零脉冲信号对应于目标空气脉冲中的零脉冲。其中，一些实施例中，目标空气脉冲信号也可以不包括零脉冲信号。当目标空气脉冲信号包括正脉冲信号和负脉冲信号时，或者当目标空气脉冲信号包括正脉冲信号、零脉冲信号和负脉冲信号时：正脉冲信号的密度越大，代表该区域对应的音频信号为正，且幅值越大；反之，负脉冲信号的密度越大，代表该区域的音频信号为负，且幅值越大，正脉冲信号和负脉冲信号连续转换的区域对应音频信号的幅值小，幅值为绝对值。其中，正脉冲信号的密度是指某一时段内，正脉冲信号的数量。负脉冲信号的密度是指某一时段内，正脉冲信号的数量。
第二方面，本申请还提供一种电子设备，包括上述任一项的发声装置。电子设备发出的可听声具有较高的声压级。
附图说明
图1是本申请实施例提供的发声装置在一些实施例中的示意框图；
图2是图1所示发声装置的发声原理的示意图一；
图3是图1所示发声装置的发声原理的示意图二；
图4是图1所示发声装置的空气脉冲产生组件在一些实施例中的结构示意图；
图5是图1所示发声装置在一些使用状态下的示意图；
图6是图4所示空气脉冲产生组件在一些使用状态下的内部结构示意图；
图7是图4所示空气脉冲产生组件在另一些使用状态下的内部结构示意图；
图8是图1所示发声装置在另一些使用状态下的示意图；
图9是图4所示空气脉冲产生组件在一些使用状态下的内部结构示意图；
图10是图4所示空气脉冲产生组件在另一些使用状态下的内部结构示意图；
图11是图1所示发声装置在另一些使用状态下的示意图；
图12是图1所示发声装置的第一种调制规则的示意图；
图13是图1所示发声装置的第二种调制规则的示意图；
图14是图1所示发声装置的第三种调制规则的示意图；
图15是图1所示发声装置的第四种调制规则的示意图；
图16是图4所示空气脉冲产生组件的内部结构示意图；
图17是图1所示空气脉冲产生组件在另一些实施例中的内部结构示意图；
图18是图1所示空气脉冲产生组件在另一些实施例中的内部结构示意图；
图19是图18所示空气脉冲产生组件的内部结构示意图；
图20是图1所示空气脉冲产生组件在另一些实施例中的内部结构示意图；
图21是图1所示空气脉冲产生组件在另一些实施例中的内部结构示意图；
图22是图1所示空气脉冲产生组件在另一些实施例中的内部结构示意图；
图23是本申请实施例提供的超声换能器在一些实施例中的结构示意图；
图24是本申请实施例提供的超声换能器在另一些实施例中的结构示意图；
图25是本申请实施例提供的超声换能器在另一些实施例中的结构示意图；
图26是本申请实施例提供的超声换能器在另一些实施例中的结构示意图；
图27是图26所示超声换能器的部分结构示意图；
图28是本申请实施例提供的超声换能器在另一些实施例中的结构示意图；
图29是图28所示超声换能器的部分结构示意图；
图30是图1所示空气脉冲产生组件在另一些实施例中的结构示意图；
图31是图30所示空气脉冲产生组件的部分结构示意图。
具体实施方式
下面将结合附图对本申请实施例中的技术方案进行描述。其中，在本申请实施例的描述中，除非另有说明，“/”表示或的意思，例如，A/B可以表示A或B；文本中的“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况，另外，在本申请实施例的描述中，“多个”是指两个或多于两个。
以下，术语“第一”、“第二”等用词仅用于描述目的，而不能理解为暗示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括一个或者更多个该特征。
本申请实施例中所提到的方位用语，例如，“上”、“下”、“内”、“外”、“侧”、“顶”、“底”等，仅是参考附图的方向，因此，使用的方位用语是为了更好、更清楚地说明及理解本申请实施例，而不是指示或暗指所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请实施例的限制。
在本申请实施例的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”、“设置在……上”应做广义理解，例如，“连接”可以是可拆卸地连接，也可以是不可拆卸地连接；可以是直接连接，也可以通过中间媒介间接连接。其中，“电连接”是指彼此之间可以导通电信号。
本申请实施例提供一种发声装置以及一种应用该发声装置的电子设备。发声装置采用不 同于传统扬声器的发声方法，发声装置通过发出多个空气脉冲，形成可听声，可听声的频率低于发声装置的换能器的振动频率，可听声的声压级由多个空气脉冲的空气脉冲密度调节，从而在小体积的基础上具有较高的低频声压级。其中，电子设备可以为手机、平板、助听器、智能穿戴设备等需要通过发声装置输出音频的电子设备。智能穿戴设备可以是智能手表、增强现实(augmented reality，AR)眼镜、AR头盔或虚拟现实(virtual reality，VR)眼镜等。其中，发声装置还可以应用于全屋、智能家居、汽车等领域中，用作音频设备或音频设备中的一部分。
请结合参阅图1和图2，图1是本申请实施例提供的发声装置100在一些实施例中的示意框图，图2是图1所示发声装置100的发声原理的示意图一。
一些实施例中，发声装置100包括信号处理电路10、控制电路20及空气脉冲产生组件30。其中，信号处理电路10用于将音频信号转为目标空气脉冲信号，在一些实施例中，信号处理电路10可以依据脉冲密度调制(Pulse Density Modulation，PDM)算法，将音频信号转为目标空气脉冲信号。其中，音频信号可以由音源输出。其中，音频信号可以是数字信号或模拟信号。音频信号为模拟信号时，音频信号可以由模数转换电路转换为数字信号，模数转换电路可以为信号处理电路10的一部分，或者为独立于信号处理电路10的另一电路，本申请实施例对此不作严格限定。控制电路20用于依据目标空气脉冲信号形成控制信号，空气脉冲产生组件30用于依据控制信号发出多个空气脉冲，从而形成可听声。
其中，发声装置100可以为模块化组件，其信号处理电路10和控制电路20可以集成于发声装置100的电路组件中，电路组件通常可以包括一个或多个电路板以及一个或多个芯片及其匹配元件。或者，在一些实施例中，发声装置100应用于电子设备中时，发声装置100的信号处理电路10和/或控制电路20也可以固定于或集成于电子设备的其他部件中，本申请实施例对此不作严格限定。
其中，脉冲密度调制算法通过目标空气脉冲信号对应区域的密度表示音频信号的幅值。目标空气脉冲信号携带目标空气脉冲的相关信息，目标空气脉冲用于形成与音频信号对应的声波。目标空气脉冲信号可以包括正脉冲信号、零脉冲信号和负脉冲信号中的至少一种。正脉冲信号对应于目标空气脉冲中的正脉冲，负脉冲信号对应于目标空气脉冲中的负脉冲，零脉冲信号对应于目标空气脉冲中的零脉冲。其中，一些实施例中，目标空气脉冲信号也可以不包括零脉冲信号。图2所示的实施例中，正脉冲信号和负脉冲信号用1、-1表示。在另一些情况下，正脉冲信号和负脉冲信号也可以用1、0表示。
当目标空气脉冲信号包括正脉冲信号和负脉冲信号时，或者当目标空气脉冲信号包括正脉冲信号、零脉冲信号和负脉冲信号时：正脉冲信号的密度越大，代表该区域对应的音频信号为正，且幅值越大；反之，负脉冲信号的密度越大，代表该区域的音频信号为负，且幅值越大，正脉冲信号和负脉冲信号连续转换的区域对应音频信号的幅值小，幅值为绝对值。其中，正脉冲信号的密度是指某一时段内(也即某一时间窗内，图2中用虚线框进行了示意)，正脉冲信号的数量。负脉冲信号的密度是指某一时段内(也即某一时间窗内)，正脉冲信号的数量。
空气脉冲产生组件30依据控制信号形成第二声波，第二声波包括多个空气脉冲，空气脉冲具有一定的声压级，使得第二声波形成可听声。其中，第二声波的多个空气脉冲挤压或舒张空气，从而引起空气的密度变化。其中，第二声波在空气中的平均密度变化与可听声的平均密度变化一致，因此第二声波在空气中形成可听声，可听声可传播至人耳。第二声波的脉冲率高于期望形成的可听声的频率，也即，第二声波在可听声的单个 周期内包括多个空气脉冲，这部分空气脉冲能够拟合出可听声的单个周期的波形。例如，第二声波的脉冲率为40kHz，期望形成的可听声的频率为100Hz。其中，“平均密度”是指空间中某一位置，一定时段内空气的密度的平均值，或者时间上某一时刻，一定空间范围内空气的密度的平均值。
例如，如图2所示的实施例中，第二声波的多个空气脉冲包括正脉冲(positive pulse)P1、零脉冲(null pulse)P0(与坐标轴重合，图中未标示)和负脉冲(negative pulse)P-1。正脉冲P1和负脉冲P-1的振幅相同。在一些实施例中，可听声的声压级(例如对应于图2中的波形幅值)与空气脉冲密度正相关。例如，在某一时段内，正脉冲P1的密度越大，代表该时段的可听声的声压为正，且幅值越大，反之，负脉冲P-1的密度越大，代表该时段的可听声的声压为负，且幅值越大，正脉冲P1和负脉冲P-1连续转换的时段对应可听声的幅值小，幅值为绝对值。其中，正脉冲P1的密度是指在某一时段内(也即某一时间窗内，图2中用虚线框进行了示意)，正脉冲与负脉冲的数量差。负脉冲的密度是指在某一时段内(也即某一时间窗内)，负脉冲与正脉冲的数量差。空气脉冲密度是指在某一时段内，多个空气脉冲的正脉冲与负脉冲的数量差值，数量差值为绝对值。
示例性的，时间窗的宽度可以是20kHz分之一左右，也即与可听声的最高频率的周期相近。当然，时间窗的宽度也可以是其他时长，本申请实施例对此不作严格限定。单个时间窗内通常包括多个空气脉冲。
此外，由于可听声的声压级随第二声波的空气脉冲密度的变化而变化，也即可听声的幅值由第二声波的空气脉冲密度调节，而可听声的频率变化由可听声的幅值变化产生，因此可听声的频率可以通过调整第二声波的空气脉冲密度实现调节。
请参阅图3，图3是图1所示发声装置100的发声原理的示意图二。
示例性的，当音频信号的振幅越大时，对应的目标空气脉冲信号的正脉冲信号或负脉冲信号的密度越大；在空气脉冲产生组件30对应形成的第二声波中，空气脉冲密度越大，形成的可听声的波形振幅越大，可听声的声压级越高。
如图2和图3所示，在本申请实施例中，可听声的声压级随第二声波的空气脉冲密度的变化而变化。第二声波的空气脉冲密度越大，则可听声的声压级越高，空气脉冲密度越小，则可听声的声压级越低。
其中，空气脉冲密度的调节方式包括但不限于：在某一时段内，调节正脉冲和负脉冲的比例，和/或调节正脉冲的数量，和/或调节负脉冲的数量。调节正脉冲和负脉冲的比例，包括调节正脉冲与负脉冲的比例，或者调节正脉冲与总空气脉冲数量的比例，或者调节负脉冲与总空气脉冲数量的比例。例如，在某一时段(例如第一时段)内，正脉冲与负脉冲的数量差值越大，可听声的声压级越高；正脉冲与负脉冲的数量差值越小，可听声的声压级越低。正脉冲与负脉冲的数量差值大的情况包括正脉冲的数量明显大于负脉冲的数量，或者明显小于负脉冲的数量。再例如，在某一时段(例如第一时段)内，正脉冲与负脉冲的比例越远离1，可听声的声压级越高；正脉冲与负脉冲的比例越靠近1，可听声的声压级越低。
示例性的，第二声波的多个空气脉冲中的正脉冲P1和负脉冲P-1的声压级相同，也即幅值相同。此时，可听声的声压级调节通过调整空气脉冲密度实现。在其他一些实施例中，可听声的声压级调节也可以既调整空气脉冲密度，同时结合调整空气脉冲的声压级实现。此时，可听声的声压级的可调范围更大，发声装置的适用范围和使用场景更广。
一些实施例中，发声装置100的第二声波为超声波，第二声波的脉冲率可以高于20kHz。此时，由于第二声波的脉冲率高于可听声的最高频率，因此第二声波的多个空气脉冲能够更 好地拟合出可听声的波形，使得可听声的声压级高，且失真小。例如，当可听声的频率为中低频(20Hz-2000Hz)时，第二声波的脉冲率与可听声的频率的倍数差较大，第二声波能够形成声压级高、失真小的可听声。
在另一些实施例中，发声装置100的第二声波也可以为可听声波(低于20kHz)，第二声波的脉冲率与期望形成的可听声的频率具有一定倍数。例如，期望形成的可听声的频率为中低频(20Hz-2000Hz)时，第二声波的脉冲率可以在10kHz至20kHz的范围内，使得第二声波形成的可听声的声压级较高，失真较小。
综上，在本申请实施例中，由于发声装置100不再采用传统扬声器结构，而是发出包括多个空气脉冲的第二声波，形成可听声，同时通过控制第二声波的空气脉冲密度实现可听声的振幅调节和频率调节，从而实现音频播放。此外，第二声波的多个空气脉冲由空气脉冲产生组件30的振动构件的振动动作实现，可听声的频率低于第二声波的脉冲率，因此可听声的频率低于振动构件的振动频率。此时，当需要形成具有相同声压级的可听声时，相较于振动构件以可听声的频率进行振动所需的位移，振动构件以第二声波的脉冲率进行振动所需的位移更小。由于发声装置100通过发出第二声波，以形成可听声，因此空气脉冲产生组件30的振动构件的位移小。并且，发声装置100通过调节第二声波的空气脉冲密度即可实现可听声的振幅调节，可听声的声压级调节无需依赖于振动构件的位移或表面积，因此发声装置100通过空气脉冲产生组件30的振动构件的小位移振动，和第二声波的较高的空气脉冲密度，即可获得高声压级的可听声，发声装置100的低频频响不存在或基本不存在跌落特性，发声装置100的低频跌落明显低于12dB，发声装置100能够在小体积的情况下，具有较高的低频声压级。小体积的发声装置100在有空间要求的场景中具有更广泛的适用性。
在下文中，以发声装置100发出的第二声波为超声波，例如调制超声波为例，对发声装置100的部分结构及部分工作原理进行示例描述。
请参阅图4，图4是图1所示发声装置100的空气脉冲产生组件30在一些实施例中的结构示意图。
一些实施例中，发声装置100的空气脉冲产生组件30包括壳体1、换能器以及第一阀门3，在本实施例中，以换能器为超声换能器(ultrasonic transducer)2为例进行说明。壳体1具有内腔11和开口12，壳体1的开口12连通壳体1的内腔11与壳体1的外部空间。例如，壳体1可以包括顶壁13、底壁14及侧壁15，顶壁13与底壁14相对设置，侧壁15位于顶壁13与底壁14之间，顶壁13、底壁14及侧壁15共同围设出内腔11。其中，顶壁13形成开口12。超声换能器2安装于壳体1的内腔11，且将壳体1的内腔11分隔为前腔111和后腔112，前腔111位于后腔112与开口12之间。其中，后腔112位于底壁14与超声换能器2之间，前腔111位于超声换能器2与开口12之间。第一阀门3固定于壳体1且覆盖壳体1的开口12。在其他一些实施例中，壳体1也可以不包括顶壁13，侧壁15的一端连接于底壁14的周缘，底壁14和侧壁15共同围设出壳体1的内腔11，侧壁15的另一端形成壳体1的开口12。
其中，第一阀门3可以采用压电结构，例如：第一阀门3包括压电片，压电片的一端相对壳体1为固定端，另一端相对壳体1为活动端；压电片断电时，压电片覆盖开口12，实现关闭；压电片通电时发生形变，压电片的活动端翘起、下压或移位等，以敞开开口12，实现打开。当然，第一阀门3还可以有其他压电结构，或者第一阀门3也可以采用其他非压电结构，本申请实施例对此不作严格限定。
其中，超声换能器2用于在第一控制信号驱动下产生第一声波。第一阀门3用于在第二控制信号控制下实现打开和关闭；第一阀门3打开时，超声换能器2形成的第一声波的部分声波通过第一阀门3，形成向发声装置100的外部发出的空气脉冲；第一阀门3关闭时，超声换能器2形成的第一声波被第一阀门3阻隔，不能传播到发声装置100的外部。发声装置100通过超声换能器2与第一阀门3的配合，选择性地发出部分第一声波，形成多个空气脉冲，从而形成第二声波。
其中，第一声波为第二声波的基础声波，设置第一控制信号的频率为超声频率，第一声波为初始超声波，以通过超声换能器2与第一阀门3的配合，选择性地发出部分初始超声波，形成多个空气脉冲，使得空气脉冲产生组件30发出的第二声波为调制超声波。在其他一些实施例中，当第二声波为可听声波时，第一声波可以为可听声波或者超声波。
示例性的，控制电路20电连接超声换能器2和第一阀门3。控制电路20用于产生第一控制信号和第二控制信号。第一控制信号用于驱动超声换能器2振动，在一些实施例中，第一控制信号的频率可以大于或等于20kHz且振幅不变。其中，超声换能器2的振动构件能够在第一控制信号的驱动下往复振动，振动构件的振动频率大于或等于20kHz，也即振动构件的振动频率为超声频率，振动构件的振幅不变，形成振幅不变的初始超声波。第二控制信号用于控制第一阀门3的开关状态，使得发声装置100能够选择性地发出部分初始超声波，形成包括多个空气脉冲的调制超声波，调制超声波形成可听声。此时，可听声的频率低于超声换能器2的振动构件的振动频率。其中，第一控制信号可以包括一路或多路信号，第二控制信号可以包括一路或多路信号，第一控制信号与第二控制信号为不同的信号。
在本申请中，调制超声波的空气脉冲的类型可以包括正脉冲P1、零脉冲P0和负脉冲P-1。其中，多种脉冲类型的实现方式有多种，例如：
在第一种实现方式中：
在超声换能器2的振动构件的往复振动过程中，在振动构件离开平衡位置向上运动、至恢复到平衡位置的时段内，第一阀门3打开，前腔111的空气被推至壳体1的外部空间，超声换能器2产生正脉冲P1；在振动构件离开平衡位置向下运动至恢复到平衡位置的时段内，第一阀门3打开，壳体1的外部空间中的空气被吸至前腔111，超声换能器2产生负脉冲P-1。在振动构件的往复振动过程中，第一阀门3关闭，超声换能器2产生零脉冲P0，零脉冲P0也可以理解为不产生具有振幅的空气脉冲。其中，在本申请实施例中，振动构件向上运动是指振动构件向靠近第一阀门3的方向运动，振动构件向下运动是指振动构件向远离第一阀门3的方向运动。
请结合参阅图5至图7，图5是图1所示发声装置100在一些使用状态下的示意图，图6是图4所示空气脉冲产生组件30在一些使用状态下的内部结构示意图，图7是图4所示空气脉冲产生组件30在另一些使用状态下的内部结构示意图。其中，图6和图7中空气脉冲产生组件30的使用状态对应于图5所的使用状态。
示例性的，如图5所示，第一控制信号的波形可以为正弦波形；在0至T/2的时段内的相位为正，用于驱动超声换能器2的振动构件离开平衡位置向上运动后恢复到平衡位置；在T/2至T的时段内相位为负，用于驱动超声换能器2的振动构件离开平衡位置向下运动后恢复到平衡位置。第二控制信号的波形可以为方波；在0至T/2的对应时段内的电平为1，用于控制第一阀门3打开；在T/2至T的对应时段内的电平为0，用于控制第一阀门3关闭。
如图5和图6所示，在0至T/2的时段内，超声换能器2的振动构件离开平衡位置向上 运动后恢复到平衡位置，第一阀门3打开，前腔111的空气被振动构件推向壳体1的外部空间，超声换能器2形成的空气脉冲为正脉冲P1。如图5和图7所示，在T/2至T的时段内，超声换能器2的振动构件离开平衡位置向下运动后恢复到平衡位置，第一阀门3关闭，超声换能器2形成的空气脉冲为零脉冲P0。
请结合参阅图8至图10，图8是图1所示发声装置100在另一些使用状态下的示意图，图9是图4所示空气脉冲产生组件30在一些使用状态下的内部结构示意图，图10是图4所示空气脉冲产生组件30在另一些使用状态下的内部结构示意图。其中，图9和图10中空气脉冲产生组件30的使用状态对应于图8所的使用状态。
示例性的，如图8所示，第一控制信号的波形可以为正弦波形；在0至T/2的时段内的相位为正，用于驱动超声换能器2的振动构件离开平衡位置向上运动后恢复到平衡位置；在T/2至T的时段内相位为负，用于驱动超声换能器2的振动构件离开平衡位置向下运动后恢复到平衡位置。第二控制信号的波形可以为方波；在0至T/2的对应时段内的电平为0，用于控制第一阀门3关闭；在T/2至T的对应时段内的电平为1，用于控制第一阀门3打开。
如图8和图9所示，在0至T/2的时段内，超声换能器2的振动构件离开平衡位置向上运动后恢复到平衡位置，第一阀门3关闭，超声换能器2形成的空气脉冲为零脉冲P0。如图8和图10所示，在T/2至T的时段内，超声换能器2的振动构件离开平衡位置向下运动后恢复到平衡位置，第一阀门3打开，壳体1的外部空间的空气进入前腔111，超声换能器2形成的空气脉冲为负脉冲P-1。
在第二种实现方式中：
在超声换能器2的振动构件往复振动过程中，在振动构件向上运动的时段内，第一阀门3打开，前腔111空气被推至壳体1的外部空间，超声换能器2产生正脉冲P1；在振动构件向下运动的时段内，第一阀门3打开，壳体1的外部空间中的空气被吸至前腔111，超声换能器2产生负脉冲P-1。在振动构件往复振动过程中，第一阀门3关闭，超声换能器2产生零脉冲P0。
请参阅图11，图11是图1所示发声装置100在另一些使用状态下的示意图。
示例性的，第一控制信号的波形可以为正弦波形；在0至T/2的时段内的相位为正，用于驱动超声换能器2的振动构件离开平衡位置向上运动后恢复到平衡位置；在T/2至T的时段内相位为负，用于驱动超声换能器2的振动构件离开平衡位置向下运动后恢复到平衡位置。第二控制信号的波形可以为方波；在0至T/2的对应时段，且在振动构件向上运动的对应时段内的电平为1，用于控制第一阀门3打开，超声换能器2形成正脉冲P1；在0至T/2的对应时段，且在振动构件向下运动的对应时段内的电平为0，用于控制第一阀门3关闭，超声换能器2形成零脉冲P0；在T/2至T的对应时段，且在振动构件向下运动的对应时段内的电平为1，用于控制第一阀门3打开，超声换能器2形成负脉冲P-1；在T/2至T的对应时段，且在振动构件向上运动的对应时段内的电平为0，用于控制第一阀门3关闭，超声换能器2形成零脉冲P0。
可以理解的是，发声装置100形成调制超声波的多种空气脉冲时，可以单独采用上述第一种实现方式或者第二种实现方式，也可以结合使用上述第一种实现方式和第二种实现方式，本申请实施例对此不作严格限定。
在上述两种实现方式中，第一控制信号的波形以正弦波进行示例，空气脉冲和第二控制信号的波形以方波进行示例，可以理解的是，第一控制信号的波形也可以为三角波、方波或其他波形，空气脉冲和第二控制信号的波形也可以为正弦波、三角波或其他波形。在下文的 相关描述中，为了便于说明，仍以第一控制信号的波形以正弦波进行示例，空气脉冲和第二控制信号的波形以方波进行示例。
在本申请中，发声装置100可以通过多种调制规则，形成调制超声波。调制规则的基本原则在于依据脉冲密度调制算法将音频信号转换为目标空气脉冲信号，依据目标空气脉冲信号形成控制信号，控制信号控制空气脉冲产生组件30形成包括多个空气脉冲的调制超声波，调制超声波形成可听声，可听声与音频信号对应。其中，目标空气脉冲信号携带目标空气脉冲的相关信息，目标空气脉冲通过脉冲密度调制换算后形成的声波，与音频信号对应。由于空气脉冲产生组件30的振动构件以超声频率往复运动，形成的调制超声波的多个空气脉冲难以与目标空气脉冲完全对应，可能存在少量失真，因此通过调制规则使得调制超声波的多个空气脉冲尽量接近目标空气脉冲即可。
以下对调制规则中目标空气脉冲与调制超声波之间的转换过程进行举例说明：
第一种调制规则：
请参阅图12，图12是图1所示发声装置100的第一种调制规则的示意图。
在第一种调制规则中，调制超声波的正脉冲P1、负脉冲P-1及零脉冲P0采用前文中的第一种实现方式。
第一控制信号的频率为目标空气脉冲的脉冲率的二分之一。其中，本申请实施例中，目标空气脉冲的脉冲率是指目标空气脉冲能够进行类型选择的最大频率，目标空气脉冲进行类型选择时，可以进行脉冲类型切换(例如正脉冲P1切换为负脉冲P-1或零脉冲P0)，也可以保持脉冲类型不变。将第一控制信号的单个周期中的前半周期定义为正半周期，对应于空气脉冲产生组件30的振动构件先离开平衡位置向上运动、然后恢复到平衡位置的时段，将第一控制信号的周期中的后半周期定义为负半周期，对应于空气脉冲产生组件30的振动构件先离开平衡位置向下运动、然后恢复到平衡位置的时段。
第二控制信号的频率可以为第一控制信号的频率的两倍。本申请实施例中，第二控制信号的频率是指能够对第二控制信号的内容进行设置或赋值的最大频率。第二控制信号的频率对应于第一阀门3能够进行开关状态选择的最大频率。开关状态选择包括，切换或维持打开状态，切换或维持关闭状态。第二控制信号处于高电平时，控制第一阀门3打开，处于低电平时，控制第一阀门3关闭。
当目标空气脉冲为正脉冲P1，第一控制信号处于正半周期时，第二控制信号设置为高电平，以在调制超声波的对应时段形成正脉冲P1；当目标空气脉冲为负脉冲P-1，第一控制信号处于负半周期时，第二控制信号设置为高电平，以在调制超声波的对应时段形成负脉冲P-1。当目标空气脉冲为零脉冲P0时，第二控制信号设置为低电平，以在调制超声波的对应时段形成零脉冲P0。此时，目标空气脉冲能够在调制超声波的对应时段实现，使得最终的可听声能够与音频信号对应。
此外，当目标空气脉冲为正脉冲P1，第一控制信号为负半周期时，或者当目标空气脉冲为负脉冲P-1，第一控制信号处于正半周期时，第二控制信号设置为低电平，以在调制超声波的对应时段形成零脉冲P0。此时，虽然目标空气脉冲在调制超声波的对应时段出现失真，但是失真程度较低，失真比例较低，因此能够降低最终的可听声相对音频信号的失真程度。
第二种调制规则：
请参阅图13，图13是图1所示发声装置100的第二种调制规则的示意图。
在第二种调制规则中，调制超声波的正脉冲P1、负脉冲P-1及零脉冲P0采用前文中的第一种实现方式。
第一控制信号的频率与目标空气脉冲的脉冲率相同。将第一控制信号的单个周期中的前半周期定义为正半周期，对应于空气脉冲产生组件30的振动构件先离开平衡位置向上运动、然后恢复到平衡位置的时段，将第一控制信号的周期中的后半周期定义为负半周期，对应于空气脉冲产生组件30的振动构件先离开平衡位置向下运动、然后恢复到平衡位置的时段。
第二控制信号的频率可以为第一控制信号的频率的两倍。第二控制信号处于高电平时，控制第一阀门3打开，处于低电平时，控制第一阀门3关闭。
当目标空气脉冲为正脉冲P1，第一控制信号处于正半周期时，第二控制信号设置为高电平，以在调制超声波的对应时段形成正脉冲P1；当目标空气脉冲为负脉冲P-1，第一控制信号处于负半周期时，第二控制信号设置为高电平，以在调制超声波的对应时段内形成负脉冲P-1。此时，目标空气脉冲能够在调制超声波的对应时段实现，使得最终的可听声能够与音频信号对应。同时，由于第一控制信号的单个完整周期对应于一个目标空气脉冲，第二控制信号的频率为第一控制信号的频率的两倍，因此可以依据目标空气脉冲的类型，准确地控制第一阀门3在第一控制信号的正半周期及负半周期打开或闭合，使得调制超声波最终获得与目标空气脉冲匹配的空气脉冲，调制超声波的失真程度低。
在上述第一种调制规则和第二种调制规则中，第一控制信号的频率容易因空气脉冲产生组件30的振动构件的材料、结构、尺寸等因素的限制，当两种调制规则的第一控制信号的频率相同时，第一种调制规则的目标空气脉冲的脉冲率为第二种调制规则的目标空气脉冲的脉冲率的两倍。此时，第一种调制规则可以通过高脉冲率的目标空气脉冲，使得调制超声波即使存在少量失真，仍然可以实现音频信号的高质量转换，使得可听声的音质较高、声压级较高。第二种调制规则虽然目标空气脉冲的脉冲率较低，但是由于调制超声波的失真小，因此也可以实现音频信号的高质量转换，使得可听声的音质较高、声压级较高。
第三种调制规则：
请参阅图14，图14是图1所示发声装置100的第三种调制规则的示意图。
在第三种调制规则中，调制超声波的正脉冲P1、负脉冲P-1及零脉冲P0采用前文中的第二种实现方式。
第一控制信号的频率为目标空气脉冲的脉冲率的二分之一。将第一控制信号的单个周期中的前半周期定义为正半周期，对应于空气脉冲产生组件30的振动构件先离开平衡位置向上运动、然后恢复到平衡位置的时段，将第一控制信号的周期中的后半周期定义为负半周期，对应于空气脉冲产生组件30的振动构件先离开平衡位置向下运动、然后恢复到平衡位置的时段。也即，在第一控制信号的单个周期中的上升阶段，振动构件向上运动，在第一控制信号的单个周期中的下降阶段，振动构件向下运动。
第二控制信号的频率可以为第一控制信号的频率的四倍。第二控制信号处于高电平时，控制第一阀门3打开，处于低电平时，控制第一阀门3关闭。
当目标空气脉冲为正脉冲P1，第一控制信号处于上升阶段时，第二控制信号设置为高电平，以在调制超声波的对应时段形成正脉冲P1；当目标空气脉冲为负脉冲P-1，第一控制信号处于下降阶段时，第二控制信号设置为高电平，以在调制超声波的对应时段内形成负脉冲P-1。此外，当目标空气脉冲为正脉冲P1，第一控制信号处于下降阶段时，第二控制信号设置为低电平，以在调制超声波的对应时段形成零脉冲P0；当目标空气脉冲为负脉冲P-1，第一控制信号处于负半周期的上升阶段时，第二控制信号设置为低电平，以在调制超声波的对应时段内形成零脉冲P0。
在第三种调制规则中，由于第一控制信号的半个周期对应于一个目标空气脉冲，第二控 制信号的频率为第一控制信号的频率的四倍，因此可以依据目标空气脉冲的类型，准确地控制第一阀门3在第一控制信号的上升阶段或下降阶段的打开或闭合，使得调制超声波最终获得与目标空气脉冲匹配的空气脉冲，调制超声波形成的可听声能够与音频信号对应，可听声的失真程度低。
第四种调制规则：
请参阅图15，图15是图1所示发声装置100的第四种调制规则的示意图。
在第四种调制规则中，调制超声波的正脉冲P1、负脉冲P-1及零脉冲P0采用前文中的第二种实现方式。
第一控制信号的频率小于目标空气脉冲的脉冲率的二分之一，例如第一控制信号的频率为目标空气脉冲的脉冲率的三分之一。在第一控制信号的单个周期包括上升阶段和下降阶段，上升阶段对应于空气脉冲产生组件30的振动构件向上运动的阶段，下降阶段对应于空气脉冲产生组件30的振动构件向下运动的阶段。
第二控制信号的频率明显大于第一控制信号的频率，可以依据目标空气脉冲和第一控制信号灵活设置，以尽量降低调制超声波相对于目标空气脉冲的失真程度。例如，第二控制信号处于高电平时，控制第一阀门3打开，处于低电平时，控制第一阀门3关闭。当目标空气脉冲为正脉冲P1，第一控制信号处于上升阶段时，第二控制信号设置为高电平，以在调制超声波的对应时段内形成正脉冲P1；当目标空气脉冲为负脉冲P-1，第一控制信号处于下降阶段时，第二控制信号设置为高电平，以在调制超声波的对应时段内形成负脉冲P-1。此外，当目标空气脉冲为正脉冲P1，第一控制信号处于下降阶段时，第二控制信号设置为低电平，以在调制超声波的对应时段形成零脉冲P0；当目标空气脉冲为负脉冲P-1，第一控制信号处于负半周期的上升阶段时，第二控制信号设置为低电平，以在调制超声波的对应时段内形成零脉冲P0。
上述第一调制规则至第四调制规则为发声装置100的调制规则中的部分调制规则，发声装置100还可以有其他调制规则，本申请实施例不进行严格限定。
在发声装置100的调制规则中，第二控制信号的频率可以大于或等于两倍的第一控制信号的频率，使得第一阀门3能够在空气脉冲发声组件的振动构件的一次往复振动中实现至少两次开关状态的选择，发声装置100能够顺利发出正脉冲P1、和/或负脉冲P-1、和/或零脉冲P0，调制超声波能够通过空气脉冲密度的调节实现可听声的频率调节及振幅调节。
可以理解的是，当第二控制信号的频率低于两倍的第一控制信号的频率时，第一阀门3的开关状态的选择频率过低，第一阀门3的打开时长或关闭时长超过空气脉冲发声组件的振动构件的半个振动周期，易导致调制超声波产生正脉冲P1和负脉冲P-1的非期望的能量抵消，会产生能量浪费、声压级下降等问题。
在发声装置100的调制规则中，调制超声波的多个空气脉冲的脉冲率与第二控制信号的频率相同，调制超声波的多个空气脉冲的脉冲率为空气脉冲能够进行类型选择的最大频率，空气脉冲进行类型选择时，可以进行脉冲类型切换(例如正脉冲P1切换为负脉冲P-1或零脉冲P0)，也可以保持脉冲类型不变，例如上述第一调制规则至第四调制规则。
示例性的，在发声装置100的调制规则中，第二控制信号的频率可以等于两倍的第一控制信号的频率，调制超声波的正脉冲P1的最大密度与第一控制信号的频率相同，调制超声波的负脉冲P-1的最大密度与第一控制信号的频率相同，例如上述第一调制规则和第二调制规则。
在上述调制规则中，第一控制信号的振幅不变，以驱动超声换能器2的振动构件的振 幅不变，产生振幅不变的初始超声波。此时，初始超声波为单频超声波，超声换能器2的振动构件的工作频段为窄频段，振动构件只需要在单点具有较高的响应，因此超声换能器2能够更好地利用振动构件的共振频率实现响应，从而提高能量转化效率，有利于提高声压级。
在其他一些实施例中，第一控制信号的振幅也可以是变化的，第一控制信号的振幅变化使得空气脉冲的声压级发声变化，此时，发声装置100能够通过调整第二声波的空气脉冲密度及空气脉冲的声压级，实现可听声的声压级调节，可听声的声压级调节范围更广。例如，在增加第二声波的空气脉冲密度的情况下，同时增加至少部分空气脉冲的声压级，以进一步提高可听声的声压级。
发声装置100基于上述发声方式和调制规则，可以具有多种实现结构，以下进行举例说明。
请再次参阅图4，一些实施例中，空气脉冲产生组件30的壳体1的内腔11被超声换能器2分隔为前腔111和后腔112。示例性的，发声装置100可以单独通过超声换能器2分隔壳体1的内腔11，以形成前腔111和后腔112。在其他一些实施例中，发声装置100也可以通过超声换能器2与其他结构(例如壳体1的部分结构)配合，共同分隔壳体1的内腔11，以形成前腔111和后腔112，本申请实施例对此不作严格限定。
其中，空气脉冲产生组件30具有连通孔16，连通孔16用于连通前腔111和后腔112，以实现前腔111和后腔112的气压平衡，使得超声换能器2能够顺畅振动，从而在第一控制信号的驱动下形成失真程度小的初始超声波。示例性的，连通孔16可以设于超声换能器2。
其中，连通孔16的最小宽度大于粘滞层厚度dμ，粘滞层厚度f为第一控制信号的频率。连通孔16的最小宽度是指单个连通孔16的最窄的位置处的尺寸。
在本实施例中，通过设置连通孔16的尺寸，连通孔16实现前腔111与后腔112之间的声学连通，使得前腔111空气和后腔112的空气能够在超声换能器2往复振动的过程中，顺畅地通过连通孔16实现互相流动，以更好地实现前腔111和后腔112的气压平衡。
其中，连通孔16的形状可以有多种，能实现声学连通即可，形状可以包括但不限于圆孔、方孔、长条孔、狭缝等，本申请实施例不作严格限定。其中，连通孔16的数量可以有一个或多个，本申请实施例不作严格限定。其中，声学连通是指声音能够穿过。
示例性的，壳体1设有后泄孔17，后泄孔17连通壳体1的后腔112与壳体1的外部空间，以实现后腔112与壳体1的外部空间的气压平衡。其中，后泄孔17的形状可以有多种，能实现透气即可，形状可以包括但不限于圆孔、方孔、长条孔、狭缝等，本申请实施例不作严格限定。其中，后泄孔17的数量可以有一个或多个，本申请实施例不作严格限定。
其中，发声装置100还可以设有第一阻尼网布18，第一阻尼网布18可以通过粘接等方式固定于壳体1，且覆盖后泄孔17。第一阻尼网布18透气，使得空气脉冲产生组件30仍可以通过后泄孔17实现后腔112与壳体1的外部空间的气压平衡。此外，第一阻尼网布18能够实现后腔112与壳体1的外部空间之间的声学隔离，使得后腔112中的声波不会泄露至壳体1的外部空间。其中，透气是指界面两侧的介质可以交换，声学隔离是指声音无法穿透。第一阻尼网布18的数量、形状等与后泄孔17相适配。在其他一些实施例中，发声装置100也可以不设置第一阻尼网布18，本申请实施例不作严格限定。
请参阅图16，图16是图4所示空气脉冲产生组件30的内部结构示意图。
一些实施例中，超声换能器2包括振动构件21和支撑件22，振动构件21固定于支撑件22。振动构件21用于在第一控制信号的驱动下往复运动，以形成初始超声波。其中，支撑件22固定连接壳体1，使得超声换能器2安装于壳体1的内腔11。前腔111位于振动构件21朝向第一阀门3的一侧，后腔112位于振动构件21背向前腔111的一侧。
示例性的，支撑件22可以固定连接壳体1的侧壁15。第一阀门3可以固定连接壳体1的顶壁13，前腔111位于第一阀门3及顶壁13与振动构件21之间，后腔112位于振动构件21与底壁14之间。
示例性的，连通孔16可以设置于支撑件22。在其他一些实施例中，连通孔16也可以形成于振动构件21与支撑件22之间的间隙中。当然，连通孔16还可以有其他实现结构，本申请实施例对此不作严格限定。
在空气脉冲产生组件30中，初始超声波在前腔111传输时，容易因声波反射、相反相位的声波抵消等现象，导致空气脉冲产生组件30最终发出的调制超声波容易出现失真、能量损耗大等问题。
示例性的，在振动构件21的垂直方向上，第一阀门3与振动构件21之间的距离H1小于λ/2，λ为初始超声波的波长。在本实施例中，第一阀门3与振动构件21之间的距离会影响到初始超声波的相位延迟，通过设置第一阀门3与振动构件21之间的距离小于λ/2，从而能够降低初始超声波在前腔111传输时的损耗，改善调制超声波的容易出现失真、能量损耗大等问题，提高了空气脉冲产生组件30的能量转换效率，有利于提高可听声的声压级。
在空气脉冲产生组件30中，振动构件21往复振动时，振动构件21同样会于后腔112产生另一超声波，该超声波在后腔112中传播、反射，部分超声波会经连通孔16传输至前腔111，而与初始超声波发生叠加，这部分超声波在后文中称为后腔反射声波。
示例性的，在振动构件21的垂直方向上，后腔112的高度H2在M*λ+λ/4-λ/8至M*λ+λ/4+λ/8的范围内，λ为初始超声波的波长，M为自然数。其中，后腔112的高度H2可以为振动构件21与壳体1的底壁14之间的距离。在本实施例中，后腔反射声波的相位与初始超声波的相位相同或相近，后腔反射声波与初始超声波的叠加产生增强效果，从而有利于提高可听声的声压级。
例如，后腔112的高度H2可以在M*λ+λ/4-λ/9至M*λ+λ/4+λ/9的范围内，或者在M*λ+λ/4-λ/10至M*λ+λ/4+λ/10的范围内，以获得更佳的声波叠加效果，更高的可听声的声压级。
示例性的，在振动构件21的垂直方向上，后腔112的高度H2在M*λ+λ/2-λ/8至M*λ+λ/2+λ/8的范围之外，以避免后腔反射声波与初始超声波的叠加产生抵消问题，以降低调制超声波的失真。
例如，后腔112的高度H2尽量在M*λ+λ/2-λ/9至M*λ+λ/2+λ/9的范围之外，或者在M*λ+λ/2-λ/10至M*λ+λ/2+λ/10的范围之外。
请参阅图17，图17是图1所示空气脉冲产生组件30在另一些实施例中的内部结构示意图。本实施例的空气脉冲产生组件30可以包括前文实施例空气脉冲产生组件30的大部分技术特征，以下主要描述两者的区别，两者相同的内容不再赘述。
一些实施例中，发声装置100的空气脉冲产生组件30还设有吸音件19，吸音件19安装于后腔112中。其中，吸音件19可以是吸音棉、或者局域共振吸音结构、或者其他吸音类结构等。吸音件19的设置可以减弱或消除振动构件21向后腔112发出的超声波，从而减弱或消除后腔反射声波，降低后腔反射声波对调制超声波的影响，以提高可听声的声压级。通过 仿真计算，空气脉冲产生组件30增加吸音件19后，可听声的声压级提高了3dB以上，同时失真降低。
其中，吸音件19在后腔112内的安装方案有多种。示例性的，吸音件19可以为板状结构或层状结构。一些示例中，吸音件19可以固定于壳体1的底壁14，吸音件19覆盖底壁14的部分区域或全部区域。另一些示例中，吸音件19还可以固定于壳体1的侧壁15中面向后腔112的区域，以增加吸音件19的吸音面积。在其他一些实施例中，吸音件19也可以是较为立体的结构件，固定于后腔112内即可。可以理解的是，吸音件19与振动构件21之间形成一定的间距，该间距对应的空间用作振动构件21的振动空间，以避免吸音件19对振动构件21的振动造成干扰。
一些实施例中，由于空气脉冲产生组件30的后腔112设有吸音件19，因此后腔112的高度设计更为灵活，后腔112的高度可以与前文实施例(例如图16对应实施例)相同或不同。
可以理解的是，在图16对应实施例中，当空气脉冲产生组件30的后腔112高度小于λ/4时，λ为初始超声波的波长，后腔反射声波易进入前腔111，对前腔111中的初始超声波的相位造成干扰，导致调制超声波的失真严重。在图17对应实施例中，示例性的，在振动构件21的垂直方向上，后腔112的高度小于λ/4。此时，空气脉冲产生组件30通过在后腔112设置吸音件19，以减弱或消除后腔反射声波，从而降低调制超声波的失真，并且可以使后腔112的高度小于λ/4，从而降低空气脉冲产生组件30的整体高度，有利于空气脉冲产生组件30及发声装置100的小型化。
示例性的，后腔112的高度可以在1mm以内，后腔112内设有吸音件，后腔112的高度例如可以为0.95mm、0.8mm、0.87mm等，使得空气脉冲产生组件30及发声装置100的整体高度小，体积小，并且调制超声波的失真小。其中，第一控制信号的频率可以在40kHz左右。
请结合参阅图18和图19，图18是图1所示空气脉冲产生组件30在另一些实施例中的内部结构示意图，图19是图18所示空气脉冲产生组件30的内部结构示意图。
本实施例的空气脉冲产生组件30可以包括前文实施例空气脉冲产生组件30的大部分技术特征，两者的主要区别在于：在本实施例中，空气脉冲产生组件30的连通孔16设于壳体1。连通孔16设于壳体1时，连通孔16的加工难度较低，并且能够降低超声换能器2的加工难度和成本。本实施例空气脉冲产生组件30的其他设计可以参考前文实施例的相关描述，此处不再赘述。
可以理解的是，在其他一些实施例中，空气脉冲产生组件30的连通孔16为多个时，也可以部分连通孔16形成于超声换能器2，部分连通孔16形成于壳体1。
请参阅图20，图20是图1所示空气脉冲产生组件30在另一些实施例中的内部结构示意图。本实施例的空气脉冲产生组件30可以包括前文实施例空气脉冲产生组件30的大部分技术特征，以下主要描述两者的区别，两者相同的内容不再赘述。
一些实施例中，空气脉冲产生组件30还包括第二阀门4，第二阀门4可以设于超声换能器2。第二阀门4打开时连通前腔111与后腔112，以平衡前腔111与后腔112的压力；第二阀门4关闭时隔断前腔111与后腔112。本实施例与前文实施例的区别在于，通过可选择性导通的第二阀门4替代连通孔16，以更灵活地调节前腔111与后腔112的连通情况。
其中，第二阀门4可以采用压电结构，例如：第二阀门4包括压电片，压电片的一端相对壳体1为固定端，另一端相对壳体1为活动端；压电片断电时，压电片隔断前腔111与后腔112，实现关闭；压电片通电时发生形变，压电片的活动端翘起、下压或移位等，以连通 前腔111与后腔112，实现打开。当然，第二阀门4还可以有其他压电结构，或者第二阀门4也可以采用其他非压电结构，本申请实施例对此不作严格限定。
示例性的，发声装置100的控制电路20(参阅图1)还电连接第二阀门4，控制电路20还用于产生第三控制信号，第三控制信号用于控制第二阀门4的开关状态。
其中，在超声换能器2的空气脉冲产生组件30的振动构件的往复振动过程中，第二阀门4可以依照任意规则打开，以实现前腔111与后腔112的压力平衡。第二阀门4的开关时刻、开关时长及开关状态的切换频率的设置均较为灵活，第三控制信号受到第一控制信号及第二控制信号的限制较少。
此外，为保证空气脉冲产生组件30的前腔111与后腔112的压力状态能够满足振动构件顺利振动的基本需要，降低振动构件振动的失真程度，第二阀门4的打开频率不应过低。例如，第三控制信号用于控制第二阀门4的打开周期小于或等于二十倍的第一控制信号的周期。也即，在超声换能器2的振动构件振动二十个周期的时段内，第二阀门4至少打开一次，以连通前腔111与后腔112，平衡前腔111与后腔112的压力。
其中，第二阀门4打开时的导通截面的最小宽度大于粘滞层厚度dμ，粘滞层厚度f为第一控制信号的频率。导通截面的最小宽度是指导通截面的最窄的位置处的尺寸。在本实施例中，第二阀门4导通时形成前腔111与后腔112之间的声学连通。
其中，当第二阀门4始终处于打开状态时，第二阀门4也可以视为连通孔。
示例性的，空气脉冲产生组件30在结构实现方案中，可以在超声换能器2上设置通孔、缝隙或缺口等导通空间，第二阀门4覆盖该导通空间，以在第二阀门4打开时，连通前腔111与后腔112，在第二阀门4关闭时，隔断前腔111与后腔112。本申请实施例对具体的结构实现方案不作严格限定。
请参阅图21，图21是图1所示空气脉冲产生组件30在另一些实施例中的内部结构示意图。
本实施例的空气脉冲产生组件30可以包括前文实施例空气脉冲产生组件30(例如图20对应实施例)的大部分技术特征，两者的主要区别在于：在本实施例中，空气脉冲产生组件30的第二阀门4设于壳体1。第二阀门4设于壳体1时，能够降低超声换能器2的加工难度和成本。本实施例空气脉冲产生组件30的其他设计可以参考前文实施例的相关描述，此处不再赘述。
请参阅图22，图22是图1所示空气脉冲产生组件30在另一些实施例中的内部结构示意图。本实施例的空气脉冲产生组件30可以包括前文实施例空气脉冲产生组件30的大部分技术特征，以下主要描述两者的区别，两者相同的内容不再赘述。
一些实施例中，空气脉冲产生组件30的壳体1的内腔11被超声换能器2分隔为前腔111和后腔112，前腔111与后腔112互不连通。也即，在空气脉冲产生组件30的工作过程中，前腔111与后腔112始终保持隔断、不连通的状态。示例性的，壳体1设有前泄孔110，前泄孔110连通壳体1的前腔111与壳体1的外部空间。在本实施例中，通过前泄孔110的设置，使得壳体1的前腔111与壳体1的外部空间保持压力平衡，使得超声换能器2的振动构件21能够顺利振动，形成声波。
其中，前泄孔110可以设置在壳体1的顶壁13和/或侧壁15，本申请实施例对此不作严格限定。其中，前泄孔110的形状可以有多种，能实现透气即可，形状可以包括但不限于圆 孔、方孔、长条孔、狭缝等，本申请实施例不作严格限定。其中，前泄孔110的数量可以有一个或多个，本申请实施例不作严格限定。
其中，发声装置100还可以设有第二阻尼网布120，第二阻尼网布120可以通过粘接等方式固定于壳体1，且覆盖前泄孔110。第二阻尼网布120透气，使得空气脉冲产生组件30仍可以通过前泄孔110实现前腔111与壳体1的外部空间的气压平衡。此外，第二阻尼网布120能够实现前腔111与壳体1的外部空间之间的声学隔离，使得前腔111中的声波不会泄露至壳体1的外部空间。第二阻尼网布120的数量、形状等与前泄孔110相适配。在其他一些实施例中，发声装置100也可以不设置第二阻尼网布120，本申请实施例不作严格限定。
本申请的上述发声装置100可以用于形成中低频(20Hz-2000Hz)的可听声，也可以用于形成全频段(20Hz-20000Hz)的可听声。发声装置100可以单独使用，也可以多个发声装置100组合使用，也可以与压电扬声器、动圈扬声器等其它同类型或不同类型的扬声器组合使用。例如，由本申请发声装置100实现中低频的可听声，由压电扬声器、动圈扬声器等扬声器实现高频的可听声。
在本申请中，可听声的频率取决于调制超声波的空气脉冲密度，而空气脉冲密度基于初始超声波实现，超声换能器2在第一控制信号的驱动下往复振动，以产生初始超声波，因此可听声的频率实现与第一控制信号的频率紧密相关。
一些实施例中，第一控制信号的频率小于400kHz，以使调制超声波形成频率在20Hz至2kHz范围内的可听声。另一些实施例中，第一控制信号的频率大于或等于400kHz，以使调制超声波形成频率在20Hz至20kHz范围内的可听声。在上述实施例中，第一控制信号的频率设计能够使调制超声波的失真程度较低，可听声的声压级较高。
传统扬声器为了覆盖全频段的可听声，需要振动构件在可听声频段内不能出现过于明显的共振状态，即不需要某个频点/窄频带范围内出现过高的声音，影响听感，同时需要振动构件在宽频带内具有较强的响应，这对于扬声器振动组件的要求非常高，通常比较难实现。此外，这种要求使得传统扬声器无法利用共振状态，能量利用率低，也就导致产生的声音的声压级较低。
在本申请的一些实施例中，由于超声换能器2用于往复振动以产生初始超声波，初始超声波为单频超声波，因此通过将超声换能器2的振动构件的共振频率设置为，与期望形成的初始超声波的频率相同或相近，也即与第一控制信号的频率相同或相近，可以提高超声换能器2的振动构件对第一控制信号的响应程度，能量利用率高，有利于提高可听声的声压级。
示例性的，第一控制信号的频率与超声换能器2的振动构件的共振频率相同，使得初始超声波与第一控制信号的匹配度高，有利于提高可提升的声压级。
示例性的，当超声换能器2的振动构件采用压电结构时，可以利用压电结构的高Q值的特性做驱动，以提高能量转换效率，超声换能器2的能量利用率高。其中，Q值叫做品质因数，高Q值意味着低的声波能量损耗(其衰减率则与频率平方成正比)。
超声换能器2可以具有多种基础实现结构，下文进行举例说明，下文中的超声换能器2的结构能够应用于前文描述的任一种空气脉冲产生组件30。
请参阅图23，图23是本申请实施例提供的超声换能器2在一些实施例中的结构示意图。
一些实施例中，超声换能器2可以为压电超声换能器。超声换能器2包括支撑件22和振动构件21，振动构件21包括振膜211及压电片212，振膜211的周缘固定于支撑件22，压电片212固定于振膜211的中部。示例性的，压电片212包括一个压电材料层，此时超声换 能器2为压电单晶超声换能器。其中，压电材料层可以采用锆钛酸铅压电陶瓷(lead zirconate titanate piezoelectric ceramics，简称为PZT)等压电材料。压电片212可以通过胶层213粘接在振膜211上。其中，压电片212可以位于振膜211的上表面或下表面，本申请实施例对此不作严格限定。振膜211可以采用铝等材料。在本实施例中，由于压电片212的高Q值特性，超声换能器2具有较高的能量转换效率。
其中，通过调整超声换能器2的材料和几何尺寸，能够调整超声换能器2的振动构件21的共振频率，使得共振频率位于期望的频率范围内。示例性的，设计振动构件21的共振频率为40kHz，以适用于需要形成中低频的可听声的发声装置100。以压电片212采用圆片形结构进行示例说明，压电材料为PZT-5H，极化方向为压电片212的厚度方向，对压电片212的上下表面施加电压，压电片212的半径为4mm，厚度为0.8mm。振膜211的材料为铝，厚度为0.2mm。此时，振动构件21的共振频率为40kHz或接近40kHz。
本实施例的超声换能器2主要用于发出频率小于400kHz的初始超声波。其中，通过减小压电片212的面积，和/或增加压电片212的厚度，和/或增加振膜211材料的厚度，和/或增加振膜211材料的硬度，可以提升振动构件21的共振频率，以使共振频率匹配期望的初始超声波的频率。具体方案可以依据实际需求进行设计，此处不进行赘述。当然，在一些设计中，本实施例的超声换能器2也可以用于发出频率在400kHz以上的初始超声波。
如图23所示，一些实施例中，超声换能器2还可以包括声波指向件23，声波指向件23位于振动构件21的上方，声波指向件23用于对超声换能器2产生的初始超声波的辐射方向进行限制，以提高初始超声波的辐射效率，有利于提高可听声的声压级。其中，声波指向件23可以包括锥状发射面231，锥状发射面231能够将初始超声波的指向性收窄到60°左右，明显提高了初始超声波的辐射效率。
请参阅图24，图24是本申请实施例提供的超声换能器2在另一些实施例中的结构示意图。本实施例的超声换能器2可以包括前文实施例超声换能器2的大部分技术特征，以下主要描述两者的区别，两者相同的内容不再赘述。
一些实施例中，超声换能器2的振动构件21的压电片212可以包括多个堆叠设置的压电材料层，多个压电材料层中至少有两个压电材料层的极化方向相反或者施加电压方向相反。此时，超声换能器2为压电双晶超声换能器。
示例性的，压电片212包括两个压电材料层，例如压电片212包括第一压电材料层2121和第二压电材料层2122。第一压电材料层2121和第二压电材料层2122的极化方向相反，或者，第一压电材料层2121和第二压电材料层2122的施加电压方向相反。可以理解的是，在其他一些实施例中，压电片212也可以包括三个或更多个压电材料层。
请参阅图25，图25是本申请实施例提供的超声换能器2在另一些实施例中的结构示意图。本实施例的超声换能器2可以包括前文实施例超声换能器2的大部分技术特征，以下主要描述两者的区别，两者相同的内容不再赘述。
一些实施例中，超声换能器2包括支撑件22和振动构件21，振动构件21为压电片，压电片固定于支撑件22。压电片可以包括一个或多个压电材料层，压电材料层可以采用锆钛酸铅压电陶瓷等压电材料。压电片包括多个压电材料层时，多个压电材料层堆叠设置。
在本实施例中，超声换能器2可以采用较厚的压电陶瓷块作为压电片，由压电片直接构成振动构件21，无需振膜，从而具有较高的共振频率。例如，本实施例超声换能器2的振动构件21的共振频率可以大于或等于400kHz，例如共振频率可以设计为500kHz、600kHz等。
请结合参阅图26和图27，图26是本申请实施例提供的超声换能器2在另一些实施例中 的结构示意图，图27是图26所示超声换能器2的部分结构示意图。本实施例的超声换能器2可以包括前文实施例超声换能器2的大部分技术特征，以下主要描述两者的区别，两者相同的内容不再赘述。
一些实施例中，超声换能器2包括支撑件22和振动构件21，振动构件21包括振膜211及多个压电片212，振膜211的周缘固定于支撑件22，多个压电片212固定于振膜211的中部。其中，压电片212可以包括一个或多个压电材料层，压电片212可以为单晶压电片或双晶压电片。多个压电片212的共振频率相同。多个压电片212彼此间隔排布，例如可以呈阵列排布或者其他排布方式。
在本实施例中，超声换能器2能应用于大振动面积的使用场景中。相较于振动构件21只设置一个压电片的方案，由于压电片212的共振频率会随着压电片212的面积的增加而降低，因此难以实现高频率的超声波辐射。本实施例通过多个压电片212的设置，每个压电片212均能够具有较高的共振频率，而排布于振膜211所在平面的多个压电片212共同振动，也有利于提高初始超声波的声压级，使得发声装置100形成的可听声的声压级较高。
其中，本实施例的超声换能器2的振动构件21的共振频率可以大于或等于400kHz，从而有利于发声装置100实现全频段的发声。在其他一些实施例中，超声换能器2的振动构件21的共振频率也可以小于400kHz。
请结合参阅图28和图29，图28是本申请实施例提供的超声换能器2在另一些实施例中的结构示意图，图29是图28所示超声换能器2的部分结构示意图。本实施例的超声换能器2可以包括前文实施例超声换能器2的大部分技术特征，以下主要描述两者的区别，两者相同的内容不再赘述。
一些实施例中，超声换能器2包括支撑件22和振动构件21，振动构件21固定于支撑件22。振动构件21包括基材213和多个压电件214，基材213可以采用环氧树脂等聚合物材料，压电件214可以采用锆钛酸铅压电陶瓷等压电材料，多个压电件214嵌设于基材213内。
其中，基材213可以大致呈薄板状结构，多个压电件214沿基材213的板面方向排布，基材213的板面方向垂直于基材213的厚度方向。其中，多个压电件214间隔排布，也即相邻的两个压电件214之间形成间隙。示例性的，多个压电件214可以呈阵列排布或其他排布方式。图29中示意出了振动构件21的部分区域的结构，图29中只对其中一个压电件214进行标号。
在本实施例中，振动构件21采用压电复合结构，相较于纯压电陶瓷结构，在结构强度和可靠性方面得到了提升，振动构件21的共振频率较高。例如，本实施例振动构件21的共振频率可以大于或等于400kHz。当然，在其他一些实施例中，超声换能器2的振动构件21的共振频率也可以小于400kHz。
此外，本实施例振动构件21的压电复合结构有利于制备大面积的压电件阵列，压电件阵列中的多个压电件214的共振频率相同，振动构件21通过设置较多数量的压电件214，能够提高振动构件21形成的初始超声波的声压级，从而提高发声装置100形成的调制超声波的声压级，使得可听声的声压级较高。
另一些实施例中，超声换能器2也可以采用聚偏氟乙烯(polyvinylidene difluoride，PVDF)压电薄膜超声换能器。超声换能器2的振动构件为聚偏氟乙烯压电薄膜，聚偏氟乙烯压电薄膜可以通过简单的约束方式，实现在弯曲表面或者平面上进行超声波发射，且频率较高，振动构件的共振频率一般在1MHz至100MHz的范围内。此时，超声换能器2的振动构件能够较为容易地获得400kHz以上的共振频率。当然，在其他一些实施例中，超声换能器2的振 动构件21的共振频率也可以有其他共振频率，例如小于400kHz。
另一些实施例中，超声换能器2也可以采用微机械超声换能器(Micromachined Ultrasonic Transducer，MUT)。例如，超声换能器2可以采用电容式微机械超声换能器(capacitive micromechanical ultrasonic transducer，cMUT)或者压电式微机械超声换能器(piezoelectric micro mechanical ultrasonic transducer，pMUT)。本实施例超声换能器2的振动构件的共振频率通常较高，例如可以大于或等于400kHz。当然，在其他一些实施例中，超声换能器2的振动构件21的共振频率也可以小于400kHz。
其中，电容式微机械超声换能器和压电式微机械超声换能器均为采用MEMS(Micro-Electro-Mechanical System，微机电系统)工艺制造的微型超声换能器。电容式微机械超声换能器一般是通过在硅衬底上形成空腔，空腔顶面为振膜材料，如氮化物等，并通过电极材料施加信号，进而实现超声波发射。压电式微机械超声换能器一般是通过在硅衬底上叠加压电类材料，如锆钛酸铅压电陶瓷等，同样通过电极施加信号后会因为逆压电效应而产生超声波。这两类基于MEMS工艺的超声换能器2可以方便地实现阵列化设计，有利于提高振动构件形成的初始超声波的声压级，从而提高发声装置100形成的调制超声波的声压级，使得可听声的声压级较高。
可以理解的是，除了前文实施例，超声换能器2也可以有其他实现结构，本申请实施例对此不作严格限定。
前文实施例的空气脉冲产生组件30以包括一个超声换能器2为例进行描述。在其他一些实施例，空气脉冲产生组件30也可以包括多个超声换能器2，以下进行举例说明。
请结合参阅图30和图31，图30是图1所示空气脉冲产生组件30在另一些实施例中的结构示意图，图31是图30所示空气脉冲产生组件30的部分结构示意图。本实施例的超声换能器2可以包括前文实施例超声换能器2的大部分技术特征，以下主要描述两者的区别，两者相同的内容不再赘述。
一些实施例中，空气脉冲产生组件30包括多个超声换能器2，多个超声换能器2均安装于壳体1的内腔11，且均位于前腔111与后腔112之间，多个超声换能器2的振动构件的共振频率相同。其中，超声换能器2的结构可以采用前文描述的任一种结构。其中，多个超声换能器2可以呈阵列排布或者呈其他排布方式。
在本实施例中，空气脉冲产生组件30能够应用于大体积、大横向空间的使用场景中。本实施例空气脉冲产生组件30通过多个超声换能器2的设置，每个超声换能器2的振动构件均能够具有较高的共振频率，同时能够提高初始超声波的声压级，使得发声装置100形成的可听声的声压级较高。
示例性的，本实施例的超声换能器2的振动构件的共振频率可以大于或等于400kHz，从而有利于发声装置100实现全频段的发声。在其他一些实施例中，超声换能器2的振动构件的共振频率也可以小于400kHz。
以上实施例仅用以说明本申请的部分技术方案，而非对其限制；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：在不冲突的情况下，其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换，或者对不同实施例所记载的技术方案进行组合，而这些修改、替换或组合，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围。

Claims (22)

  1. 一种发声装置，其特征在于，包括壳体、换能器、第一阀门及控制电路，所述壳体具有内腔和开口，所述壳体的开口连通所述壳体的内腔与所述壳体的外部空间，所述换能器安装于所述壳体的内腔，且将所述壳体的内腔分隔为前腔和后腔，所述前腔位于所述后腔与所述开口之间，所述第一阀门固定于所述壳体且覆盖所述壳体的开口；
    所述控制电路电连接所述换能器和所述第一阀门，所述控制电路用于产生第一控制信号和第二控制信号，所述第一控制信号被配置为驱动所述换能器的振动构件振动，所述第二控制信号被配置为控制所述第一阀门的开关状态，所述发声装置发出多个空气脉冲，形成可听声；
    其中，所述可听声的频率低于所述换能器的振动构件的振动频率，多个所述空气脉冲包括正脉冲和负脉冲，所述可听声的声压级随所述正脉冲和所述负脉冲的比例变化或数量变化而变化。
  2. 根据权利要求1所述的发声装置，其特征在于，在第一时段内，所述正脉冲与所述负脉冲的数量差值越大，所述可听声的声压级越高。
  3. 根据权利要求2所述的发声装置，其特征在于，多个所述空气脉冲的所述正脉冲和所述负脉冲的声压级相同。
  4. 根据权利要求1至3中任一项所述的发声装置，其特征在于，所述第一控制信号的频率大于或等于20kHz且振幅不变。
  5. 根据权利要求4所述的发声装置，其特征在于，所述第二控制信号的频率大于或等于两倍的所述第一控制信号的频率。
  6. 根据权利要求4所述的发声装置，其特征在于，所述第二控制信号的频率等于两倍的所述第一控制信号的频率，所述正脉冲的最大密度与所述第一控制信号的频率相同。
  7. 根据权利要求1至6中任一项所述的发声装置，其特征在于，所述发声装置还包括第二阀门，所述第二阀门设于所述换能器或所述壳体，所述第二阀门打开时连通所述前腔与所述后腔。
  8. 根据权利要求7所述的发声装置，其特征在于，所述控制电路电连接所述第二阀门，所述控制电路还用于产生第三控制信号，所述第三控制信号用于控制所述第二阀门的打开周期小于或等于二十倍的所述第一控制信号的周期。
  9. 根据权利要求1至6中任一项所述的发声装置，其特征在于，所述换能器或所述壳体设有连通孔，所述连通孔连通所述前腔与所述后腔。
  10. 根据权利要求1至6中任一项所述的发声装置，其特征在于，所述前腔与所述后腔互不连通，所述壳体设有前泄孔，所述前泄孔连通所述壳体的前腔与所述壳体的外部空间。
  11. 根据权利要求1至10中任一项所述的发声装置，其特征在于，所述壳体设有后泄孔，所述后泄孔连通所述壳体的后腔与所述壳体的外部空间。
  12. 根据权利要求1至11中任一项所述的发声装置，其特征在于，所述第一控制信号的频率小于400kHz，以使所述发声装置形成频率在20Hz至2kHz范围内的可听声；
    或者，所述第一控制信号的频率大于或等于400kHz，以使所述发声装置形成频率在20Hz至20kHz范围内的可听声。
  13. 根据权利要求1至11中任一项所述的发声装置，其特征在于，
    所述换能器包括支撑件、振膜及压电片，所述振膜的周缘固定于所述支撑件，所述压电 片固定于所述振膜的中部，所述振膜和所述压电片形成的振动构件的共振频率小于400kHz；
    或者，所述换能器包括支撑件和压电片，所述压电片固定于所述支撑件，所述压电片的共振频率大于或等于400kHz；
    或者，所述换能器包括支撑件、振膜及多个压电片，所述振膜的周缘固定于所述支撑件，多个所述压电片固定于所述振膜的中部，多个所述压电片的共振频率相同，所述振膜及多个所述压电片形成的振动构件的共振频率大于或等于400kHz；
    或者，所述换能器的振动构件包括基材和多个压电件，所述基材采用聚合物材料，多个所述压电件嵌设于所述基材内，所述振动构件的共振频率大于或等于400kHz；
    或者，所述换能器采用聚偏氟乙烯压电薄膜换能器、电容式微机械换能器或压电式微机械换能器，所述换能器的振动构件的共振频率大于或等于400kHz。
  14. 根据权利要求1至11中任一项所述的发声装置，其特征在于，所述发声装置包括多个所述换能器，多个所述换能器均安装于所述壳体的内腔，且位于所述前腔与所述后腔之间，多个所述换能器的振动构件的共振频率相同且均大于或等于400kHz。
  15. 根据权利要求13或14所述的发声装置，其特征在于，所述第一控制信号的频率与所述换能器的振动构件的共振频率相同。
  16. 根据权利要求1至12中任一项所述的发声装置，其特征在于，所述换能器包括振动构件，所述振动构件用于在所述第一控制信号的驱动下往复运动，形成第一声波。
  17. 根据权利要求16所述的发声装置，其特征在于，在所述振动构件的垂直方向上，所述第一阀门与所述振动构件之间的距离小于λ/2，λ为所述第一声波的波长。
  18. 根据权利要求17所述的发声装置，其特征在于，在所述振动构件的垂直方向上，所述后腔的高度在M*λ+λ/4-λ/8至M*λ+λ/4+λ/8的范围内，λ为所述第一声波的波长，M为自然数。
  19. 根据权利要求16或17所述的发声装置，其特征在于，所述发声装置还设有吸音件，所述吸音件安装于所述后腔中。
  20. 根据权利要求19所述的发声装置，其特征在于，在所述振动构件的垂直方向上，所述后腔的高度小于λ/4。
  21. 根据权利要求1至20中任一项所述的发声装置，其特征在于，所述发声装置还包括信号处理电路，所述信号处理电路用于依据脉冲密度调制算法将音频信号转为目标空气脉冲信号，所述控制电路用于依据所述目标空气脉冲信号，形成所述第一控制信号和所述第二控制信号。
  22. 一种电子设备，其特征在于，包括权利要求1至21中任一项所述的发声装置。
PCT/CN2023/087374 2022-04-14 2023-04-10 发声装置和电子设备 WO2023198005A1 (zh)

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CN109756830A (zh) * 2018-02-06 2019-05-14 索尼昂荷兰有限公司 用于听力设备的电子电路和内耳件
US10425732B1 (en) * 2018-04-05 2019-09-24 xMEMS Labs, Inc. Sound producing device
CN110839195A (zh) * 2018-08-17 2020-02-25 知微电子有限公司 发声装置与阀
CN111669688A (zh) * 2019-03-05 2020-09-15 知微电子有限公司 发声装置

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CN109756830A (zh) * 2018-02-06 2019-05-14 索尼昂荷兰有限公司 用于听力设备的电子电路和内耳件
US10425732B1 (en) * 2018-04-05 2019-09-24 xMEMS Labs, Inc. Sound producing device
CN110351636A (zh) * 2018-04-05 2019-10-18 知微电子有限公司 发声装置、扬声器及扬声器系统
CN110839195A (zh) * 2018-08-17 2020-02-25 知微电子有限公司 发声装置与阀
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