KR102861379B1 - Air-Pulse Generating Device, Wearable Sound Device, Fanless Blower, and Airflow Producing Method - Google Patents

Abstract

An air pulse generator, a wearable sound device, a fanless blower, and an airflow generation method are disclosed. The air pulse generator includes a film structure configured to operate to generate a plurality of air pulses at an ultrasonic pulse rate. The plurality of air pulses generate a net airflow directed in a single direction.

Description

Air-Pulse Generating Device, Wearable Sound Device, Fanless Blower, and Airflow Producing Method

The present invention relates to an air pulse generator, a wearable sound device and a fanless blower thereof, and more particularly, to an air pulse generator, a wearable sound device and a fanless blower thereof that improve user experience.

As electronic devices (such as smartphones and tablets) become thinner, they require increasingly complex computations, which in turn consume more battery power. Thermal management is becoming increasingly important for the future viability of these (palm-sized) electronic devices.

Additionally, wearing headphones in wet ears can shorten their lifespan or make it difficult to dry your ears. Therefore, it may be advisable to dry your ear canals after water-related activities (e.g., swimming or surfing) or showering.

Accordingly, the main purpose of the present application is to provide an air pulse generator, a wearable sound device and a fanless blower thereof to improve the shortcomings of the prior art.

One embodiment of the present application discloses an air-pulse generating device comprising a film structure actuated to generate a plurality of air pulses at an ultrasonic pulse rate, the plurality of air pulses producing a net airflow in a single direction.

One embodiment of the present application discloses a wearable sound device, the wearable sound device including an air pulse generating device configured to generate a plurality of air pulses to ventilate a housing and an external auditory canal.

One embodiment of the present application discloses a fanless blower, wherein the fanless blower generates a plurality of air pulses in response to air pressure variation, wherein the plurality of air pulses are asymmetrical; and the plurality of air pulses generated by the fanless blower constitute a net air movement or net airflow in one direction.

One embodiment of the present application discloses a method of generating an airflow, the method comprising the step of: an air pulse generating device generating a plurality of asymmetric air pulses at an ultrasonic pulse rate, the plurality of asymmetric air pulses generating a net airflow oriented in a single direction.

These and other objects of the present invention will undoubtedly become apparent to those skilled in the art after reading the following detailed description of preferred embodiments illustrated in the various drawings and figures.

Figure 1 is a schematic diagram of an air pulse generating device according to one embodiment of the present invention.
FIG. 2 illustrates waveforms of a demodulation drive signal and a modulation drive signal according to one embodiment of the present invention.
Figure 3 illustrates simulated results corresponding to the device of Figure 1.
Figure 4 plots the simulated frequency response of the sound pressure level of the APG device of Figure 1.
Figure 5 illustrates simulated results corresponding to the device of Figure 1.
Figure 6 illustrates simulated results corresponding to the device of Figure 1.
Figure 7 is a schematic diagram of an air pulse generating device according to one embodiment of the present invention.
Figure 8 is a schematic diagram of an air pulse generating device according to one embodiment of the present invention.
Figure 9 illustrates the frequency response of the energy transfer ratio of the device of Figure 1.
Figure 10 illustrates the frequency response of the energy transfer ratio of the device of Figure 8.
Figure 11 illustrates a process of a manufacturing method for the device of Figure 8.
Figure 12 is a schematic diagram of an air pulse generating device according to one embodiment of the present invention.
Figure 13 illustrates a driving signal wiring method according to embodiments of the present invention.
Figure 14 illustrates the SPL measurement results for the frequency of the device of Figure 12.
Figure 15 illustrates the SPL measurement results for peak-to-peak voltage of the device of Figure 12.
Figure 16 is a schematic diagram of an air pulse generator according to one embodiment of the present invention.
Figure 17 is a schematic diagram of an air pulse generator according to one embodiment of the present invention.
Figure 18 illustrates full cycle pulses within one operating cycle with different degrees of asymmetry.
Figure 19 illustrates a system view of the functions of each component and its corresponding frequency domain effects.
Figure 20 is a schematic diagram of an air pulse (AP) according to one embodiment of the present invention.
FIG. 21 illustrates waveforms of a demodulation signal and a modulation signal according to one embodiment of the present invention.
Figure 22 is a schematic diagram of different configurations of an APG device according to one embodiment of the present invention.
Figure 23 is a schematic diagram of an APG device of a host device according to one embodiment of the present invention.
Figure 24 is a schematic diagram of an APG device of a host device according to one embodiment of the present invention.
Figure 25 is a schematic diagram of an APG device of a host device according to one embodiment of the present invention.

The fundamental aspect of the present invention relates to an air pulse generator, and more particularly to an air pulse generator comprising modulation means and demodulation means, wherein the modulation means generates an ultrasonic air pressure wave/variation (UAW) having a frequency f _UC , the amplitude of which is modulated in accordance with an input audio signal (S _IN ), which is an electrical (analog or digital) representation of a sound signal (SS). This amplitude modulated ultrasonic air pressure wave/variation (AMUAW) is then synchronously demodulated by demodulation means such that spectral components embedded in the AMUAW are shifted by ± n · f _UC , where n is a positive integer. As a result of this synchronous demodulation, spectral components of the AMUAW corresponding to the sound signal (SS) are partially transmitted to baseband, whereby an audible sound signal (SS) is reproduced. Here, the amplitude modulated ultrasonic pressure wave/change (AMUAW) may correspond to a carrier component having an ultrasonic carrier frequency f _UC and a modulation component corresponding to an input audio signal (S _IN ).

FIG. 1 is a schematic diagram of an air-pulse generator (APG) device (100) according to one embodiment of the present invention. The device (100) may be applied as a sound generating device that generates acoustic sound according to an input (audio) signal (S _IN ), but is not limited thereto.

The device (100) includes a device layer (12) and a chamber definition layer (11). The device layer (12) includes support structures (123R, 123L) that support thin film layers that are etched on walls (124L, 124R) and flaps (101, 103, 105, 107). In one embodiment, the device layer (12) can be manufactured by a Micro Electro Mechanical Systems (MEMS) manufacturing process using, for example, a Si substrate having a thickness of 250 to 500 μM, which can be etched to form 123L/R and 124R/L. In one embodiment, a thin layer, typically 3-6 μM thick, made of a silicon on insulator (SOI) or a poly-lysine on insulator (POI) layer is etched on top of the Si substrate to form flaps (101, 103, 105, 107).

A chamber defining layer (which may also be considered/named a “cap” structure) (11) includes a pair of chamber sidewalls (110R, 110L) and a chamber ceiling (117). In one embodiment, the chamber defining layer (or cap structure) (11) may be fabricated using MEMS fabrication techniques. A resonance chamber (115) is defined between the chamber defining layer (11) and the device layer (12).

In other words, the device (100) can be viewed as including a film structure (10) and a cap structure (11) with a chamber (115) formed therebetween. The film structure (10) can be viewed as including a modulation portion (104) and a demodulation portion (102). The modulation portion (104), which includes (modulation) flaps (105, 107), is configured to be actuated to form an ultrasonic air/acoustic wave within the chamber (115), which air/acoustic wave can be viewed as a type of air pressure change that varies both temporally and spatially. In one embodiment, the ultrasonic air/acoustic wave or air pressure change can be an amplitude DSB-SC (double-sideband suppress carrier) modulated air/acoustic wave having an ultrasonic carrier frequency f _UC . The ultrasonic carrier frequency f _UC can range from 160 KHz to 192 KHz, for example, which is much higher than the maximum frequency of sound audible to humans.

The terms air wave and acoustic wave will be used interchangeably below.

A demodulation section (102) including (demodulation) flaps (101, 103) is configured to operate synchronously with a modulation section (1104) so as to shift a spectral component of a DSB-SC modulated acoustic wave generated by the modulation section (104) by ± n × f _UC , where n is a positive integer, to generate a plurality of air pulses directed toward the ambient according to the ultrasonic air wave within the chamber (115), so that a baseband frequency component of the plurality of air pulses (generated by the demodulation section (102) according to the ultrasonic air wave within the chamber (115)) is an input (audio) signal (S _IN ) or corresponds/is related thereto, wherein the low frequency component of the plurality of air pulses may refer to a frequency component of the plurality of air pulses that is within an audible spectrum (e.g., 20 or 30 KHz or less). Here, the baseband may generally refer to an audible spectrum, but is not limited thereto.

In other words, when the device (100) is switched to a sound generation application, the modulation section (104) can be operated to form a modulated air wave according to the input audio signal (S _IN ), and the demodulation section (102) operates in synchronization with the modulation section (104) to generate a plurality of air pulses having a low frequency component as (or corresponding to/related to) the input audio signal (S _IN ). In the case of a sound generation application, f _UC is f _UC ≥ 96 KHz. Much higher than the highest frequency that humans can normally hear, such as 5×20KHz, and through the natural/environmental low-pass filtering effects on multiple air pulses (caused by the physical environment such as walls, floors, ceilings, furniture or high propagation loss of ultrasound, and the human ear system such as the external auditory canal, eardrum, malleus, incus, stapes etc.), what the listener perceives is only the audible sound or music represented by the input audio signal (S _IN ).

By way of example, Fig. 19 illustrates the frequency spectrum of a signal before and after a (de)modulation operation to conceptually/schematically show the effect of the (de)modulation operation. In Fig. 19, the modulation operation generates an amplitude modulated ultrasonic sound/air wave (UAW) having a spectrum shown as W( f ) according to an input audio signal (S _IN ), which is an electrical (analog or digital) representation of a sound signal (SS). The spectrum of S _IN /SS is represented as S( f ) in Fig. 19. The synchronous demodulation operation of generating an ultrasonic pulse array (UPA) (including multiple pulses) having a spectrum exemplified by Z ( f ) can be viewed as shifting (including steps) the spectral components of an ultrasonic acoustic/air wave (UAW) by ± n × f _UC (where n is an integer), such that the spectral components of the ultrasonic air wave (UAW) corresponding to the sound signal (SS) are partially transferred to the baseband. Therefore, as can be seen from Z( f ), the baseband components of the UPA are significant compared to the amplitude modulated UAW W( f ). The UPA propagates toward the surroundings. Through the natural/physical environment and the inherent low-pass filtering effect of the human auditory system, the spectrum Y( f ) corresponding to the sound signal (SS) can be reproduced as a result.

Note that unlike conventional DSB-SC amplitude modulation using a sinusoidal carrier, W ( f ) has components at ±3× f _UC , ±5× f _UC , and higher harmonics of f _UC (not shown in Fig. 19). This is because the carrier of the modulation of the present invention is not a pure sinusoid.

Referring again to FIG. 1, as an example of a synchronous demodulation operation, the demodulation portion (102) may be operated to form an aperture (112) at a time and location corresponding/aligned to the peak(s) of the modulated air wave. In other words, when the modulated air wave reaches a peak at the location of the aperture (112), the demodulation portion (102) may be operated so that the aperture (112) also reaches a peak.

In the embodiment shown in FIG. 1, the demodulating portion (102) forms an opening (112) at a central position between the side walls (110L, 110R) having surface-to-surface, or 111L to 111R, with a spacing of (substantially) λ _UC therebetween, meaning that the flaps (101, 103) are (substantially) λ _UC /2 away from the side walls (110L, 110R) or from the side wall surfaces (111L, 111R), where λ _UC represents a wavelength corresponding to the ultrasonic carrier frequency f _UC , i.e., λ _UC = C/ f _UC using C as the speed of sound.

In one embodiment, the demodulating portion (102) can be operated to form the aperture (112) at a valve opening rate that is synchronized with the ultrasonic carrier frequency f UC _. In the present invention, the valve opening rate that is synchronized with the ultrasonic carrier frequency f _UC generally refers to the valve opening rate multiplied by the ultrasonic carrier frequency f _UC by a rational number, i.e., f _UC × ( N / M ), where N and M represent integers. In one embodiment, the valve opening rate (of the aperture (112)) can be the ultrasonic carrier frequency f _UC . For example, the valve/aperture (112) can open every operating cycle T _CY , where the operating cycle T _CY is the reciprocal of the ultrasonic carrier frequency f _UC , i.e., T _CY = 1/ f _UC .

In the present invention, the (demodulation) modulation part (102/104) is also used to denote a (demodulation) modulation flap pair. In addition, the demodulation part (or flap pair) (102) forming the opening (112) may be considered as a virtual valve that performs an open-and-close movement (cyclically) according to a specific valve/demodulation drive signal and forms the opening (112).

In one embodiment, the modulating portion (104) can substantially generate a mode-2 (or second harmonic) resonance (or standing wave) within the resonant chamber (115), such as the pressure profile (P104) and airflow profile (U104) illustrated in FIG. 1. In this regard, the spacing between the sidewall surfaces (111L, 111R) defines a total wavelength λ _UC corresponding substantially to the ultrasonic carrier frequency f _UC , i.e., W115 λ _UC = C/ f _UC . Also, in the embodiment shown in Fig. 1, the free end of the modulation flap (105/107) is positioned by the side wall (110L/110R).

It should be noted that intermodulation (or cross-coupling) between the modulation that generates the modulated air wave and the demodulation that forms the aperture (112) may occur, which may degrade the sound quality. To improve the sound quality, it is desirable to minimize intermodulation (or cross-coupling). To achieve this (i.e., to minimize cross-coupling between the modulation and demodulation), the modulation flaps (105, 107) are driven to have common-mode movement, and the demodulation flaps (101, 103) are driven to have differential-mode movement. The modulation flaps (105, 107) having common-mode movement mean that the flaps (105, 107) are simultaneously actuated/driven so that they move in the same direction. The demodulation flaps (101, 103) having differential-mode movement mean that the flaps (101, 103) are simultaneously actuated so that they move in opposite directions. Additionally, in one embodiment, the flaps (101, 103) may be actuated to move in opposite directions with (substantially) equal displacement/magnitude.

The demodulating portion (102) can substantially generate a mode-1 (or first harmonic) resonance (or standing wave) within the resonant chamber (115), such as the pressure profile (P102) and the airflow profile (U102) formed by the demodulating portion (102) as illustrated in FIG. 1. Accordingly, the demodulating portion (102) can generate W115 It should operate at a valve operating/driving frequency f _{D_V} (corresponding to the valve/demodulation-driving signal) such that λ _{D_V} /2, where λ _{D_V} = C/ f _{D_V} , and the valve operating/driving frequency should be half of the ultrasonic carrier frequency f _UC , i.e., f _{D_V} = f _UC /2.

Common mode shift and differential mode shift can be driven by (demodulation) modulation drive signals. Fig. 2 illustrates waveforms of demodulation drive signals (S101, S103) and modulation drive signals (SM). The modulation drive signal (SM) is used to drive modulation flaps (105, 107). The demodulation drive signals (or valve drive signals) (S101, S103) are used to drive demodulation flaps (101, 103), respectively.

In one embodiment, the modulation drive signal (SM) can be viewed as a PAM (Pulse Amplitude Modulation) signal modulated according to the input audio signal (S _IN ). Furthermore, unlike conventional PAM signals, the polarity (with respect to a constant voltage) of the signal (SM) is toggled within one operating cycle T _CY . Typically, the modulation-drive signal (SM) comprises pulses with alternating polarities (with respect to a constant voltage), and the envelope/amplitude of the pulses is (substantially) identical to or corresponding/proportional to the AC (alternative current) component of the input audio signal (S _IN ). In other words, the modulation drive signal (SM) can be viewed as comprising a pulse amplitude modulation signal or a PAM modulated pulse with alternating polarities with respect to a constant voltage. In the embodiment illustrated in FIG. 2, the toggling rate of the modulation drive signal (SM) is 2× f _UC , which means that the polarity of the pulses in the modulation drive signal (SM) alternates/toggles twice in one operation cycle T _CY .

The demodulation drive signals (S101, S103) include two drive pulses with equal amplitude but opposite polarities (with respect to a constant/average voltage). In other words, at a specific time, S101 includes a first pulse having a first polarity (with respect to a constant/average voltage), and S103 includes a second pulse having a second polarity (with respect to a constant/average voltage), wherein the first polarity is opposite to the second polarity. As illustrated in FIG. 2, the toggling ratio of the demodulation drive signals (S101/S103) is f _UC , which means that the polarities of the pulses in the demodulation drive signals (S101/S103) alternate/toggle once in one operation cycle T _CY . Therefore, the toggling ratio of the modulation drive signal (SM) is twice the toggling ratio of the demodulation drive signals (S101/S103).

The slopes of S101/S103 (and the associated shaded areas) are simplified diagrams illustrating energy recycling during voltage level transitions. Note that the transition periods of signals (S101 and S103) overlap. If the piezoelectric actuators of the flaps (101/103) are predominantly capacitive loads, energy recycling can be realized using the characteristics of an LC oscillator. Details of the energy recycling concept can be found in U.S. Patent No. 11,057,692, which is incorporated herein by reference. Note that the piezoelectric actuator serves as an example and is not limited thereto.

To emphasize that the flap pair (102) is differentially driven, signals (S101, S103) may also be denoted as -SV and +SV, meaning that these drive signal pairs have the same waveform but different polarities. For example, as shown in FIG. 2 , -SV is for S101 and +SV is for S103, but this is not limiting. In one embodiment, S101 may be +SV and S103 may be -SV.

In another embodiment, under these circumstances driving signals S101= V _BIAS - SV, S103=V _BIAS + SV, there may be DC bias voltages (V _BIAS and V _BIAS ≠0). Such variations should be considered within the scope of the present disclosure.

Figure 2 also shows the difference in toggling rates between the modulation drive signal (SM) and the demodulation drive signal (±SV). The relative phase delay, which means the timing alignment between the modulation drive signal (SM) and the demodulation drive signal (±SV), can be adjusted according to actual requirements.

In one embodiment, the drive circuit for generating the signals (SM, ±SV) may include a sub-circuit configured to generate a (relative) delay between the modulation drive signal (SM) and the demodulation drive signal (±SV). The details of the sub-circuit for generating the delay are not limited. Known techniques may be incorporated into the sub-circuit. As long as the sub-circuit can generate the delay to meet the timing alignment requirements (described in more detail later), the requirements of the present invention are met and will be within the scope of the present invention.

Note that the tips of the flaps (101, 103) are at substantially the same position (center position between the side walls (111L, 111R)) and experience substantially the same air pressure at that position. Furthermore, the flaps (101, 103) move differently. Therefore, the movement of the tips of the flaps (101, 103) possesses a common-mode rejection behavior similar to the common-mode rejection known in the field of analog differential OP-amplifier circuits, which means that the difference in displacement of the tips of the demodulating flaps (101, 103) or |d ₁₀₁ - d ₁₀₃ | is hardly affected by the air pressure generated by the modulating flaps (105, 107).

Common mode rejection or modulator-to-demodulator isolation can be demonstrated by Fig. 3, which illustrates simulated results generated from an equivalent circuit model of the device (100). Curves (d ₁₀₁ , d ₁₀₃ ) represent the movement/displacement of the tips of the flaps (101, 103), respectively. As can be observed in Fig. 3, d ₁₀₁ and d ₁₀₃ vary considerably due to the acoustic pressure (P104) generated by the modulating flaps (105/107), but the differential movement represented by the curves denoted d ₁₀₁ -d ₁₀₃ in Fig. 3 remains (substantially) consistent. That is, the width/gap of the valve opening (112) will remain constant even when the modulating portion (104) is operating. In other words, modulator shift has negligible effect on the function and performance of the demodulator, which is what is meant by "modulator-to-demodulator isolation."

Meanwhile, in the case of demodulator-to-modulator isolation, since the flaps (101/103) generate first harmonic resonance or standing waves within the chamber (115), as can be seen from Fig. 1, the pressures applied to the flaps (105) and (107) by P102 have substantially the same magnitude but opposite polarities, so that the movements of the flaps (105) and (107) undergo changes (due to P102) with the same magnitude but opposite polarities. This generates two ultrasonic waves (one for 105 and the other for 107) with the same magnitude but opposite polarities. When these two ultrasonic waves propagate to a location above the valve opening (112) (indicated by the dotted line area in Fig. 1), they merge into one pressure. Since the location of this "merge" occurs at the center of the device (100) along the X-axis or X-direction at the same distance from the tips of 105 and 107, the P102 induced changes cancel/compensate each other, creating a net rest with little interference with the operation of the demodulator/virtual valve.

For example, FIG. 4 plots a simulated frequency response of sound pressure level (SPL) measured at a distance of 1 meter from the device (100) under the condition that S _IN is a 10-tone equal amplitude test signal (within 650 to 22 KHz and having the same log scale interval) and an equivalent circuit simulation model of the device (100) is used. In the present simulation, the ultrasonic carrier frequency is set to f _UC = 192 KHz and the valve operating frequency is set to f _{D_V} = f _UC /2 = 96 KHz.

Demodulator-to-modulator isolation can be evidenced by the absence of extraneous spectral components at and around 96 kHz (pointed by block arrows in Figure 4), indicating a high level of isolation.

As a result, the interference of the movements of these two flap pairs (101/103 vs. 105/107) is minimized through common mode (in the modulator) vs. differential mode (in the demodulator) orthogonality/alignment.

Additionally, the percentage of time the valve remains open, or duty factor, is an important factor affecting the output of the device (100). Increasing the amplitude of the driving voltages (S101, S103) increases the amplitude of the movement of the flaps (101, 103), thereby increasing the maximum opening width of the valve opening (112), and increasing the driving voltage also increases the duty factor of the valve opening. In other words, the duty factor of the valve opening (112) and the maximum opening width/gap of the valve opening (112) can be determined by the driving voltages (S101, S103).

When the opening duty factor of the valve approaches 50%, as generated from one of the previously mentioned equivalent circuit simulation models, as illustrated by the example shown in FIG. 5, the period of each valve opening, as illustrated by the curve labeled V(opening) > 0, overlaps with the same half-cycle of an amplitude-modulated ultrasonic standing wave at a location above the valve opening (112) (indicated by the dotted line area in FIG. 1). By synchronizing and timing the opening-closing of the valve opening (112) with the in-chamber standing wave, as illustrated by the curve labeled V(p_vlv) in FIG. 5, a nicely shaped output pressure pulse, as illustrated by the curve labeled V(ep_vlv), is generated.

In Fig. 5, the curve labeled V(d2)-V(d3) represents the difference in displacement of the flaps (101, 103), i.e., d ₁₀₁ -d ₁₀₃ , and the curve labeled V(opening) represents the opening of the virtual valve (112). V(opening) > 0 when |V(d2)-V(d3)| > TH, where TH is a threshold value defined by parameters such as the thickness of the flaps (101, 103), the slit width between the flaps (101, 103), the boundary layer thickness, etc. A well-ordered form of V(ep_vlv) may imply that the pulse illustrated by V(ep_vlv) is highly asymmetric, unlike V(p_vlv), which is highly symmetric. The asymmetry of the output pressure pulses indicates the low frequency components (i.e., frequency components in the audible band) of the air pulses generated by the air pulse generator or simply the APG device, which is a desirable feature for an APG device. The higher the asymmetry, the stronger the baseband frequency components of the air pulses. A zoomed-out view of FIG. 5 is illustrated in FIG. 6, which shows the asymmetry of V(ep_vlv) corresponding to the envelope of a baseband sound signal of 1.68 KHz. In the present invention, the aperture (112) is open/formed or in the open state when the displacement difference between the flaps (101) and the flaps (103) is greater than a threshold, for example, |V(d2)-V(d3)| > TH, and otherwise it is closed or in the closed state.

Also, it has been observed that maximum output occurs when the duty factor of the valve opening, defined as |V(d2)-V(d3)| > TH, is equal to or slightly greater than 50%, such as in the range of 55-60%, but is not limited thereto. However, when the duty factor of the valve opening is much higher than 50%, such as in the range of 80-85%, more than half a cycle of the ultrasonic standing wave within the chamber passes through the valve, causing leading portions of the standing waves having different polarities to cancel each other, thereby lowering the net SPL output from the device (100). Therefore, it is generally desirable to keep the duty factor of the valve opening close to 50%, typically in the range of 50% to 70% (wherein a duty factor of between 45% and 70% is within the scope of the present invention).

In addition to the duty factor, to ensure modulator-to-demodulator isolation, it is proposed that the resonant frequency f _{R_V} of the demodulator flap (101/103) be sufficiently deviated from the ultrasonic carrier frequency f _UC , which is another design factor.

For any given thickness of the flap (101/103), it can be observed that the higher the resonance-to-drive ratio ( f _{R_V} : f _{D_V} or f _{R_V} / f _{D_V} ), the wider the valve can open, under the constraint that the valve opening duty factor is 50%. Since the output of the device (100) is positively related to the maximum valve opening width, it is desirable that the resonance-to-drive ratio be higher than 1.

However, when f _{R_V} is within the range of f _UC ± max( f _SOUND ), the flap (101/103) begins to resonate with an AM ultrasonic standing wave, converting some of the ultrasonic energy into a common-mode deformation of the flap (101/103), where max( f _SOUND ) may represent the maximum frequency of the input audio signal (S _IN ). This common-mode deformation of the flap (101/103) changes the volume above the flap (101/103), resulting in pressure variations inside the chamber (115) near the valve opening (112) over the affected frequency range, thereby lowering the SPL output.

To avoid frequency response variation due to valve resonance, it is desirable to design the flaps (101/103) with a resonant frequency outside the range of ( f _UC ±max( f _SOUND )) × M, where M is a safety margin that covers factors such as but not limited to manufacturing tolerances, temperature, altitude, etc. In general, it is desirable that f _{R_V} is significantly lower than f _UC , such as f _{R_V} ≤( f _UC - 20KHz) × 0.9, or significantly higher than f _UC , such as f _{R_V} ≥( f _UC + 20KHz) × 1.1. Note that 20KHz is used here because it is well accepted as the highest frequency audible to humans. In applications such as HD-/Hi-Res Audio, 30KHz or 40KHz may also be adopted as max( f _SOUND ), and the above formula should be modified accordingly.

Also, we assume that w ( t ) and z ( t ) represent time functions for the amplitude modulated ultrasonic acoustic/air wave (UAW) and the ultrasonic pulse array (UPA) (consisting of multiple pulses). Since the apertures (112) are formed periodically with the opening rate of the ultrasonic carrier frequency f _UC , the ratio function of z ( t ) to w ( t ), which is denoted by r ( t ) and can be expressed as r ( t ) = z ( t ) / w ( t ), is periodic with the opening rate of the ultrasonic carrier frequency f _UC . In other words, z ( t ) can be viewed as the product of w ( t ) and r ( t ) in the time domain, i.e., z ( t ) = r ( t ) · w ( t ), and the synchronous demodulation operation performed in the UAW can be viewed as the product of w ( t ) and r ( t ) in the time domain. This means that z ( t ) can be viewed as the convolution of W ( f ) and R ( f ) in the frequency domain, i.e., Z(f) = R ( f )* W ( f ), where * denotes the convolution operator, and the synchronous demodulation operation performed in UAW can be viewed as the convolution of W ( f ) and R ( f ) in the frequency domain. Note that when r ( t ) is periodic in the time domain with a rate of frequency f _UC , R ( f ) is discrete in the frequency domain such that the frequency/spectral components of R ( f ) are equally spaced by f _UC . Therefore, the convolution or synchronous demodulation operation of W ( f ) and R ( f ) involves/consists of shifting W ( f ) (or the spectral components of UAW) by ± n × f _UC , where n is an integer. Here, r ( t )/ w ( t )/ z ( t ) and R ( f ) /W ( f )/ Z(f) form a Fourier transform pair.

FIG. 12 is a schematic diagram of an APG device (400) according to one embodiment of the present invention. The device (400) is modified from FIG. 7 of U.S. patent application Ser. No. 17/553,806 and is similar to the device (100) illustrated in FIG. 1 of the present invention. Unlike the device (100), the device (400) includes only a pair of flaps (102) (but no pair of flaps (104). The pair of flaps (102) are configured to perform both a demodulation operation (forming apertures (112) synchronized to an ultrasonic carrier wave amplitude-modulated at frequency f _UC to generate air pulses according to the envelope of the amplitude-modulated ultrasonic pressure change) as well as a modulation operation (forming an air pressure change amplitude-modulated at the ultrasonic carrier frequency f _UC ).

In Fig. 12, U104 and P104 represent pressure profiles and airflow profiles formed by the flap pair (102) in response to a modulation drive signal (SM), and U102 and P102 represent pressure profiles and airflow profiles formed by the flap pair (102) in response to a demodulation drive signal (±SV). Here, the demodulation drive signal is represented as ±SV to emphasize that the flap pair (102) is differentially driven (meaning that the demodulation drive signals +SV and -SV have the same magnitude but opposite polarity) to perform the demodulation operation. For example, S101 and/or S103 may be represented as -SV and/or +SV.

In other words, the modulator and demodulator are co-located in/as a flap pair (102). As with the device (100), the film structure (10) of the flap pair (102) of the device (400) is operated to have a common mode shift for performing modulation and a differential mode shift for performing demodulation.

In other words, the " modulation operation " and the " demodulation operation " are performed simultaneously by the same flap pair (102). This colocation of the " modulation operation " with the " demodulation operation " is achieved by a novel drive signal wiring scheme as illustrated in FIG. 3. Assuming that the device (400) may include an actuator (101A/103A) disposed on the flap (101/103) and that the actuator (101A/103A) includes an upper electrode and a lower electrode, both the upper electrode and the lower electrode may receive a modulation drive signal (SM) and a demodulation drive signal (±SV).

In one embodiment, one electrode of the actuator (101A/103A) can receive a common mode modulated drive signal (SM); and the other electrode can receive a differential mode demodulated drive signal (S101(-SV)/S103(+SV)). For example, diagrams (431 to 433) illustrated in FIG. 13 illustrate details of the region (430) illustrated in FIG. 12. As illustrated in diagrams (431, 432), the lower electrode of the actuator (101A/103A) receives the common mode modulated drive signal (SM); and the upper electrode of the actuator (101A/103A) receives the differential mode demodulated drive signal (S101(-SV)/S103(+SV)). An appropriate bias voltage (V _BIAS ) can be applied to the lower electrode (as shown in diagram (432)) or the upper electrode (as shown in diagram (432)), where the bias voltage (V _BIAS ) can be determined according to actual requirements.

In one embodiment (as shown in diagram 433), one electrode of the actuator (101A/103A) can receive both the common mode modulation drive signal (SM) and the differential mode demodulation drive signal (S101(-SV)/S103(+SV)); the other electrode is suitably biased. In the embodiment shown in diagram (433), the lower electrode receives the common mode modulation drive signal (SM) and the differential mode demodulation drive signal (S101(-SV)/S103(SV)); the upper electrode is biased.

The drive signal wiring scheme illustrated in FIG. 13 achieves the goal that the applied signal of one actuator (e.g., 101A) is or includes -SM-SV (without considering V _BIAS ), while the applied signal of the other actuator (e.g., 103A) is or includes -SM+SV. Note that the drive signal wiring scheme can be modified or changed depending on actual situations/requirements. As long as the common mode signal component between the two applied signals applied to the flap pair (102) includes the modulated drive signal (SM(V _BIAS plus)), and the differential mode signal component between the two applied signals applied to the flap pair (102) includes the demodulated drive signal (SV), the requirements of the present invention are satisfied and are within the scope of the present invention. Here (or generally), the common mode signal component between two arbitrary signals a and b can be expressed as ( a + b )/2; The differential mode signal component between two arbitrary signals a and b can be expressed as ( a - b )/2.

Additionally, to minimize cross-coupling between the modulation operation (resulting from the drive signal SM) and the demodulation operation (resulting from the drive signals ±SV), in one embodiment, the flaps (101, 103) are made as a mirrored/symmetric pair in both mechanical configuration, dimensions and electrical characteristics. For example, the cantilever length of the flap (101) should be the same as that of 103; the membrane structure of the flap (101) should be the same as that of the flap (103); the position of the virtual valve (112) should be centered between or equally spaced from the two supporting walls (110) of the flaps (101) and (103); and the actuator pattern deposited on the flap (101) should mirror the pattern of the flap (103). The metal wiring for the actuators deposited on the flaps (101, 103) must be symmetrical. Here, some items are referred to as mirrored/symmetrical pairs (or flaps (101, 103) are mirrored/symmetrical), but are not limited thereto.

FIG. 14 illustrates a set of frequency response measurement results of a physical embodiment of the device (400) in an IEC711 occluded ear emulator, where the driving scheme illustrated in diagram (431) is used to drive the device (400), the Vrms for the modulated drive signal (SM) to the lower electrode is 6 Vrms, the Vpp (peak-to-peak voltage) for the demodulated drive signal (±SV) to the upper electrode is swept from 5 Vpp to 30 Vpp, and the GRAS RA0401 ear simulator is used for the acoustic result measurements. The operating frequency of the device (400) (i.e., the ultrasonic carrier frequency f _UC ) is 160 KHz, and the device dimensions are designed accordingly (i.e., W115 for C = 336 m/s). λ _UC = C / f _UC As can be seen in Fig. 14, the device (400) can produce sound with high SPL in the low frequency band (at least 99 dB for frequencies less than 100 Hz).

Also, FIG. 15 illustrates and analyzes the measurement results of the device (400) illustrated in FIG. 14. In FIG. 15, the SPL at 100 Hz (bold dashed line) and 19 Hz (bold solid line) of FIG. 14 is plotted against Vvtop (Vpp), where Vvtop (Vpp) is the peak-to-peak voltage for the demodulation drive signal applied to the upper electrode as illustrated in the connection diagram (431). It can be seen from FIGS. 14 and 15 that the SPL increases as Vvtop increases. In addition, the simulation results of the equivalent lumped-circuit model of the device (100) also showed that the SPL increases as the amplitude of the (valve drive or) demodulation drive signal increases. Therefore, it can be seen that the volume of the sound generated by the air pulse generator of the present invention can be controlled through the amplitude of the demodulation drive signal.

Based on the results of FIGS. 14 and 15, it can be concluded that the concept of modulator-demodulator co-location is valid, meaning that the modulation (forming amplitude-modulated ultrasonic pressure changes) and demodulation (synchronously forming apertures to generate asymmetric air pulses) performed by the device (400) successfully generate the APPS effect. Therefore, it may be possible to reduce the chamber width (e.g., W115 of the device (100)).

Fig. 17 is a schematic diagram of an APG device (C00) according to one embodiment of the present invention. The device (C00) is similar to the previously introduced APG device and includes flaps (101, 103). The flaps (101, 103) can also be driven by the driving method illustrated in Fig. 13.

Unlike these devices, device (C00) does not include a cap structure. Compared to the APG devices introduced above, device (C00) has a much simpler structure, requiring fewer photolithography etching steps, eliminating complex conduit fabrication steps, and eliminating the need to bind two subcomponents or subassemblies together. This significantly reduces the production cost of device (C00).

Since no chamber to be compressed is formed under the cap structure, the acoustic pressure generated by the device (C00) is mainly caused by the acceleration of the movement of the flaps (101, 103). By aligning the opening timing of the virtual valve (112) (responsive to the modulation drive signal (±SV)) with the acceleration timing of the common mode movement of the flaps (101, 103) (responsive to the modulation drive signal (SM)), the device (C00) can generate an asymmetric air (pressure) pulse.

Note that the space surrounding the flaps (101, 103) is divided into two subspaces, one in the subspace Z>0 or +Z and one in the subspace Z<0 or -Z. For any common mode movement of the flaps (101, 103), a pair of acoustic pressure waves will be generated, one in the subspace Z and the other in the subspace -Z. These two acoustic pressure waves have equal magnitude but opposite polarity. Consequently, when the virtual valve (112) opens, the pressure differences between the two air volumes near the virtual valve (112) will be neutralized. Therefore, when the timing at which the differential mode movement reaches its peak, i.e. the timing at which VV (112) reaches its maximum opening, is aligned with the acceleration timing at which the common mode movement reaches its peak, the acoustic pressure that should be generated by the common mode movement is suppressed/eliminated by the opening of the virtual valve (112), resulting in an automatic neutralization between the two acoustic pressures on the two opposite sides of the flaps (101, 103), where the two acoustic pressures are equal in magnitude but opposite in polarity. This means that when the virtual valve (112) opens, the device (C00) generates (almost) net-zero air pressure. Therefore, when the opening period of the virtual valve (112) overlaps with the period of one of the (two) polarities of the acceleration of the common mode flap movement, the device (C00) generates a single-ended (SE) or SE-like air pressure waveform/pulse, which is highly asymmetric.

In the present invention, an SE (semi-polar) waveform may mean that the waveform is (substantially) unipolar for a certain level. An SE acoustic pressure wave may mean a waveform that is (substantially) unipolar for an ambient pressure (e.g., 1 ATM).

Note that the opening of the virtual valve (112) does not determine the strength/amplitude of the acoustic pressure pulse, but rather how strong the "near-zero pressure" (or auto-neutralization) effect is. When the virtual valve (112) is wide open, the "near-zero pressure" effect is strong, auto-neutralization is complete, the asymmetry will be strong/obvious, and consequently, the baseband signal or APPS effect will be strong/significant. Conversely, when the virtual valve (112) is narrow open, the "near-zero pressure" effect is weak, auto-neutralization is incomplete, the asymmetry is low, and the baseband signal or APPS effect is weak.

In the FEM simulation, the device (C00) can generate 145 dB SPL at 20 Hz. From the FEM simulation, even though the SPL generated by the device (C00) is about 12 dB lower than that generated by the device (600) (about 157 dB SPL at 20 Hz), the total harmonic distortion (THD) of the device (C00) is 10 to 20 dB lower than that of the device (600) under the same driving conditions. Therefore, the simulation verifies the efficacy of the device (C00), which is an APG device without a cap structure or a chamber formed inside.

Note that the description that the timing of the VV opening is aligned to the peak pressure timing within the chamber or the peak velocity/acceleration of the common mode membrane movement implicitly implies that a tolerance of ± e % is allowed. That is, it is also within the scope of the present invention if the timing of the VV opening is aligned to (1 ± e %) of the peak pressure within the chamber or the peak velocity/acceleration of the common mode membrane movement, where e % can be 1%, 5% or 10% depending on the actual requirements.

With respect to pulse asymmetry, Fig. 18 illustrates full-cycle pulses (within one operating cycle T _CY ) with different degrees of asymmetry. In the present invention, the asymmetry can be evaluated as the ratio of p ₂ to p ₁ , where p ₁ > p ₂ , where p ₁ represents the peak value of a first half-cycle pulse having a first polarity with respect to the level, and p ₂ represents the peak value of a second half-cycle pulse having a second polarity with respect to the level. In the acoustic domain, the level can correspond to an ambient condition such as ambient pressure (zero acoustic pressure) or zero acoustic airflow, where the air pulse in the present invention can refer to an airflow pulse or a barometric pressure pulse.

Figure 18(a) illustrates a full cycle pulse with r = p ₂ / p ₁ > 80%. As shown in Figure 18(a) or r = p ₂ / p ₁ A full cycle pulse of 1 has low asymmetry. Fig. 18(b) illustrates a full cycle pulse with 40% ≤ r = p ₂ / p ₁ ≤ 60%. As shown in Fig. 18(b) or r = p ₂ / p ₁ A full cycle pulse with a 50% asymmetry has a moderate asymmetry. Fig. 18(c) illustrates a full cycle pulse with r = p ₂ / p ₁ < 30%. A full cycle pulse as shown in Fig. 18(c) or with r = p ₂ / p ₁ → 0 has a high asymmetry.

As discussed above, the higher the asymmetry, the stronger the APPS effect and baseband spectral components of the ultrasonic air pulse. In the present invention, an asymmetric air pulse refers to an air pulse with at least a moderate asymmetry, meaning r = p ₂ / p ₁ ≤ 60%.

It should be noted that the demodulation operation of the APG device of the present invention generates an asymmetric air pulse based on the amplitude of the ultrasonic pressure change generated through the modulation operation. In one respect, the demodulation operation of the present invention is similar to the rectifier of an AM (amplitude modulation) envelope detector in a wireless communication system.

In a wireless communication system known in the art, an envelope detector, which is a type of wireless AM (noncoherent) demodulator, includes a rectifier and a low-pass filter. The envelope detector generates an envelope corresponding to an input amplitude-modulated signal. The input amplitude-modulated signal of the envelope detector is typically highly symmetrical, with r = p ₂ / p ₁ → 1. One goal of the rectifier is to transform the symmetric amplitude-modulated signal so that the rectified amplitude-modulated signal becomes highly asymmetrical, with r = p ₂ / p ₁ → 0. After low-pass filtering the highly asymmetric rectified AM signal, the envelope corresponding to the amplitude-modulated signal is recovered.

The demodulation operation of the present invention, which converts a symmetrical ultrasonic pressure change ( r = p ₂ / p ₁ → 1) into an asymmetrical air pulse ( r = p ₂ / p ₁ → 0), is similar to a rectifier in an envelope detector such as an AM demodulator, where the low-pass filtering operation is left to the natural environment and the human auditory system (or a sound detection device such as a microphone ₎ to recover the sound/music corresponding to the input audio signal (S IN ) or to be perceived by the listener or measured by a sound detection device.

Creating asymmetry is crucial to the demodulation operation of an APG device. In the present invention, pulse asymmetry relies on appropriate opening timing aligned with the membrane (flap) movement that generates the ultrasonic pressure change. Different APG configurations will have different timing alignment methods. In other words, the timing of forming the opening (112) is determined so that the multiple air pulses generated by the APG device are asymmetric.

An APG device that generates asymmetric air pulses can also be applied to air pump/transport applications, which may be used for heat dissipation, ventilation, or may have cooling, drying, or other functionalities. In this regard, the APG device of the present invention can also be considered as (a type of) air flow generating device.

Note that conventional loudspeakers (e.g., dynamic drivers) that use physical surface movement to generate sound waves face the problem of front- and back-radiating wave cancellation. When a physical surface moves, causing air mass movement, a pair of sound waves are generated: a front-radiating wave and a back-radiating wave. These two waves largely cancel each other out, resulting in a net SPL that is significantly lower than that measured solely from the front- and back-radiating waves.

Commonly adopted solutions to the problem of front/rear radiation cancellation involve utilizing a rear enclosure or an open baffle. Both solutions require physical dimensions comparable to the wavelength of the lowest frequency of interest, for example, a 1.5-meter wavelength at 230 Hz.

Compared to conventional speakers, the APG device of the present invention occupies only a few tens of square millimeters (much smaller than conventional speakers) and produces tremendous SPL, especially at low frequencies.

This is achieved by generating an asymmetric amplitude modulated air pulse, wherein the demodulation portion generates a symmetric amplitude modulated air pressure change through membrane movement, and the demodulation portion generates an asymmetric amplitude modulated air pulse through a virtual valve. The modulation portion and the demodulation portion are implemented by flap pair(s) manufactured in the same manufacturing layer, thereby reducing manufacturing/production complexity. The modulation operation is performed through common-mode movement of the flap pair, and the demodulation operation is performed through differential-mode movement of the flap pair, wherein the modulation operation (through common-mode movement) and the demodulation operation (through differential-mode movement) can be performed by a single flap pair. Proper timing alignment between the differential-mode movement and the common-mode movement improves the asymmetry of the output air pulse.

As mentioned above, the APG device of the present application can function as a miniature air pump, can generate asymmetric air pulses, and can be applied in cooling, drying, dehumidification, heat dissipation and/or ventilation applications, where the (asymmetric) air pulses are generated to form a constant net air movement in one direction.

Additionally, the APG device of the present invention for airflow applications can be placed within an air quality sensing device that detects, for example, the density of specific particle(s) (e.g., PM 2.5 or PM 10 (PM: Particulate Matter)) or compound(s) in the air (e.g., ozone (O ₃ ), nitrogen dioxide (NO ₂ ), sulfur dioxide (SO ₂ ), and carbon monoxide (CO)). Accordingly, the size of the air quality sensing device can be drastically reduced.

For example, FIG. 20 illustrates a schematic diagram of an air pulse (AP) according to one embodiment of the present invention. The air pulse can be generated by an APG device of the present application (e.g., C00, 500, or 100) comprising a film structure (e.g., 10). As previously mentioned, the film structure of the APG device can be actuated to perform a movement to generate the air pulse ( _AP ) at an ultrasonic pulse rate f _pulse (e.g., 96 KHz or 192 KHz), which can be, for example, the reciprocal of the operating cycle T _CY of the ultrasonic carrier frequency f _UC . In this case, the ultrasonic pulse rate f _pulse can be the ultrasonic carrier frequency f UC . The air pulse (AP) can generate a unidirectional positive airflow. Consequently, the APG device can function as a (very small) air pump.

In one embodiment, the first air pulse (AP1) can continuously generate a first net airflow in one single direction, for example, a first direction (D1). For example, as shown in FIG. 20, during a first period of time (T1), all air pulses (AP) are directed in the first direction (D1). When the first period of time (T1) is at least the reciprocal of the minimum audible frequency or longer than the reciprocal of the minimum audible frequency, the first net airflow generated by the first air pulse (AP1) can be considered to continuously direct in one single direction (D1). For example, when the minimum audible frequency is recognized as 10 Hz, when the first period of time (T1) is at least 0.1 seconds or longer than 0.1 seconds, the first net airflow can be considered to continuously direct in one single direction (D1). Note that the first amplitude(s) corresponding to the first air pulse (AP1) facing the first direction (D1) may or may not be the same.

Meanwhile, the APG device may generate a second air pulse (AP2), and the second air pulse (AP2) may generate a second net airflow that continuously points in a second direction (D2) opposite to the first direction (D1). In one embodiment, when the APG device generates significant airflow or air movement and no air pulse toggling between the first direction (D1) and the second direction (D2) is discernible, the first net airflow may be considered to be continuously pointing in the direction (D1) during the period (T1) and/or the second net airflow may be considered to be continuously pointing in the direction (D2) during the period (T2).

The film structure can be driven by a demodulation drive signal (e.g., ±SV) and a modulation drive signal (e.g., SM). Note that in this application, SM may be referred to as a modulation signal, which is a type of drive signal. Similarly, ±SV may be referred to as a demodulation signal, which is a type of drive signal.

Separately from FIG. 2, FIG. 21 illustrates schematic waveforms of a demodulation signal (±SV) and a modulation signal (SM) according to another embodiment of the present invention, ignoring its high/low voltage transitions. As illustrated in FIG. 21, the modulation/drive signal (SM) may be generated based on an input signal (e.g., S _IN ) that includes a (nonzero) direct current (DC) offset. In other words, the input signal may simply be a DC signal, but is not limited thereto.

In one embodiment, the DC offset may be related to the direction of the positive airflow. For example, during a first period (T1), the air pulse (AP) may continuously generate a first positive airflow in a first direction (D1) in response to a positive DC offset. On the other hand, during a second period (T2), the air pulse generated by the APG device may continuously generate a second positive airflow in a second direction (D2) opposite to the first direction (D1) in response to a negative DC offset. In this regard, the APG device or airflow generating device of the present invention may be viewed as a voltage-to-airflow converter capable of converting a voltage into an airflow.

In addition to the polarity of the DC offset, the direction of the forward airflow can also be determined/controlled by the phase between the modulation signal (SM) and the demodulation signal (±SV). For example, in FIG. 21, the transition of the demodulation signal (±SV) is aligned with the interval in which the modulation signal (SM) is low. In this case, the APG device can generate the airflow, for example, in the third direction. When the (phase of) the demodulation signal (±SV) is shifted such that the transition of the demodulation signal (±SV) is aligned with the interval in which the modulation signal (SM) is high, the APG device generates the airflow in the fourth direction, which is opposite to the third direction. In short, the direction of the forward airflow generated by the APG device can be determined/controlled by the phase (difference) between the modulation signal and the demodulation signal.

The net airflow strength/volume may be related to or a function of the magnitude of the DC offset. By maintaining the airflow direction (either the first or the second direction), the APG device may dissipate heat, dehumidify, provide ventilation, or promote air circulation. In this case, the APG device may be considered a fanless blower. That is, the C00, 500, or 100 may also be considered a fanless blower, especially when the drive signal or modulated drive signal applied thereto is generated according to an input signal containing a non-zero DC component/offset. The terms APG device, airflow generator, and blower may be used interchangeably in the present invention, meaning the device (100, 500, C00, or K00), which may also be referred to as, for example, an airflow generator or a blower.

Alternatively, as illustrated in FIG. 2, the input audio signal (S _IN ) may be an electrical representation of an audio sound signal, such as music. Note that the input audio signal (S _IN ) including an alternating current (AC) audio component may further include a non-zero DC voltage/offset. A modulation signal (SM) may be generated based on the input (audio) signal (S _IN ) including the DC offset. In this case, an APG device or a fanless blower may generate sound while simultaneously generating a unidirectional forward airflow.

In one embodiment, the APG device, the airflow generating device, or the fanless blower may be placed within a wearable sound device (such as an earbud), which will be discussed later. When the APG device, the airflow generating device, or the fanless blower is placed within the wearable sound device, the APG device, the airflow generating device, or the fanless blower may simultaneously achieve ear canal drying/cooling and music playback.

As mentioned above, airflow generating devices, APG devices, or fanless blowers can be used in heat dissipation applications. To dissipate heat from a heat source, the APG devices can be strategically placed near the heat source. For example, FIG. 22 is a schematic diagram of different configurations of an APG device G00 according to an embodiment of the present invention. FIG. 23 (a), (b), and (c) illustrate an APG device (G00) positioned above, below, or next to a heat source (HS), respectively. The heat source (HS) can be a CPU, a GPU, or any component that generates heat. The APG device (G00) and/or the heat source (HS) can be placed within a housing of an electronic/host device (e.g., a host computer, a wearable sound device, a laptop, a tablet, a mobile phone, an augmented reality device, a virtual reality device, or a mixed reality device).

FIG. 23 is a schematic diagram of an APG device (H00) of a host device (23HD) according to an embodiment of the present invention. For an APG device (H00) integrated within the host device (23HD) to generate airflow, the host device (23HD) may include suitable vent(s) (VNT) to establish such airflow. The vent(s) (VNT) may be a number of holes along the edge(s)/side(s) of the host device (23HD) strategically positioned to promote the desired (cooling/drying) airflow. In one embodiment, the host device (23HD) may be a personal/portable device, such as, but not limited to, a personal/portable phone.

When there is one APG device (e.g., H00) in the chamber (or host device (23HD)), the APG device (H00) can operate in pump-in mode. In pump-in mode, air enters the host device (23HD) through the APG device (H00), and the vent(s) (VNT) can serve as outlet(s) for the established airflow. When water is detected by the APG device (H00), the APG device (H00) can immediately stop pumping to prevent water from entering the host device (23HD) to prevent water damage. Alternatively, the APG device (H00) may operate in a net pump-out mode, wherein the interior space of the host device (23HD) may be in an underpressurized state to draw net airflow into the host device (23HD) through the vent(s) (VNT).

The host device may include one or more APG devices disposed within the host device. For example, FIG. 24 is a schematic diagram of APG devices (J00a, J00b) of a host device (24HD) according to one embodiment of the present invention. Two APG devices (J00a, J00b) disposed within the host device (24HD) are configured to ventilate a space within the host device (24HD). In one embodiment, the host device (24HD) may be a host computer whose dimensions (e.g., width/length/height) are not limited.

The space within the host device (24HD) may be unorganized/undivided. The host device (24HD) may lack a specific pattern designed to guide airflow. However, the placement of the APG devices (J00a, J00b) may be essential for proper cross-ventilation.

As illustrated in (a) of FIG. 24, the APG devices (J00a, J00b) may be positioned diagonally or non-facing/misaligned on/near the opposite/nonadjacent face (e.g., Wa, Wb) of the host device (24HD), but is not limited thereto. This is because positioning the APG devices (J00a, J00b) across from each other rather than directly opposite each other allows for an optimized path for air to pass through the host device (24HD). Accordingly, the airflow can be directed to where the cooling air is most needed. Moreover, low frequency sounds can be blocked without passing through the APG device (J00a or J00b), since the back waves of the APG device (J00a, J00b), which can then cancel out the individual front waves, are less likely to leak to each other with the help of the facing surface/wall (e.g. Wa, Wb) of the host device (24HD).

In one embodiment, the absence of direct mixing between the sound pressure from the APG devices (J00a, J00b) allows the host device (24HD) to employ an adaptive compensation algorithm that can utilize real-time chamber pressure data to manipulate the operation of the APG devices (J00a, J00b), thereby ensuring optimal performance without introducing unexpected errors by the APG devices (J00a, J00b) into the adaptive compensation algorithm.

In one embodiment, the APG devices (J00a, J00b) may be substantially parallel. In one embodiment, the planes (e.g., Wa, Wb) on which the APG devices (J00a, J00b) are positioned may be furthest apart. In one embodiment, the APG devices (J00a, J00b) may not be aligned in a plan view ((a) of FIG. 24) but may be aligned in a side view ((b) of FIG. 24).

The DC offset of the APG device (J00a) and the DC offset of the APG device (J00b) can have opposite polarities. This polarity contrast plays a significant role in creating a push-pull active airflow cooling pathway.

Dust accumulation in the air inlet tends to increase over time, which can gradually block the airflow. In one embodiment, for self-cleaning purposes, the DC offset of the APG device (J00a) can be switched/alternated between a first value (e.g., positive or above a threshold) and a second value (e.g., negative or below a threshold) to periodically/irregularly (e.g., every few minutes) reverse the airflow, thereby minimizing dust accumulation. Similarly, the DC offset of the APG device (J00b) can be switched between a third value (e.g., the second value, negative or below a threshold) and a fourth value (e.g., the first value, positive or above a threshold), which is synchronized with the switching of the APG device (J00a). As a result, most of the accumulated dust can be blown away, and the airflow can be maintained. This self-cleaning mechanism is particularly suitable for situations where high-heat generating applications require continuous airflow for extended periods of time (e.g., watching action movies or playing dungeon crawlers).

In one embodiment, a "puff" operation may occasionally be employed for self-cleaning purposes. For example, the APG device (J00a) may pump air at a medium rate (continuously in the first time slot) and the APG device (J00b) may pump air at a high rate (intermittently (e.g., 2-3 times) in the first time slot). Then, the roles are reversed: the APG device (J00b) may pump air at a medium rate (continuously in the second time slot) and the APG device (J00a) may pump air at a high rate (intermittently (e.g., 2-3 times) in the second time slot). The entire cycle may take about 1 second. This puffing action can be activated frequently, such as when the power button on the host device is pressed, and can be disguised by playing a motorcycle start-up sound (e.g., "pon", "pon", "pon", "pon"). As a result, most of the accumulated dust is removed and airflow is maintained.

APG devices can be placed within wearable audio devices (e.g., in-ear audio devices, earbuds, headphones, or hearing aids) to ventilate the ear canal. Ventilating/drying the ear canal can help prevent bacterial and fungal infections that can develop over time.

For example, FIG. 25 is a schematic diagram of an airflow generating device (K00) of a host device (25HD) according to one embodiment of the present invention. The host device (25HD) may be a wearable sound device such as an earbud or a hearing aid. The wearable sound device (25HD) includes an airflow generating device (K00). In order to achieve external auditory canal drying/dehumidification/ventilation, the airflow generating device (K00) is configured to provide a constant airflow or (net) air movement toward or outside the external auditory canal when the user wears it. FIG. 25(a) illustrates the host device (25HD); FIG. 25(b) and (c) provide front and back side views, respectively, of the airflow generating device (or APG device) (K00).

An airflow generating device (or APG device) (K00) within the host device (25HD) (i.e., wearable sound device) generates a constant airflow within, into, or out of the host device (25HD), thereby promoting cooling or drying of the external auditory canal, which may prevent infections caused by bacteria or fungi resulting from extended use.

Additionally, the host device (25HD) may include suitable vent(s) (e.g., on the housing (K04)) that allow pressure to be released due to low volume airflow, thereby continuously refreshing the air within the host device (25HD) or the ear canal and providing a more comfortable long-term wearing experience. In one embodiment, the vent(s) may be designed to remain permanently open, but is not limited thereto. Furthermore, the dimensions, shape(s), or position(s) of the housing (K04) are not limited and may be designed according to actual requirements.

It should be noted that the airflow generating device (e.g., K00) placed within the wearable sound device is not limited to an APG device. Any device capable of generating a constant airflow and placed within the wearable sound device should satisfy the requirements of the present invention and is within the scope of the present invention.

The strength/volume of the net airflow can be controlled/adjusted dynamically, programmatically, automatically, or manually by the user in response to the output(s) of sensors (e.g., humidity sensors or thermometers) placed within the host device (25HD).

In other words, the host device (25HD) or the wearable sound device (25HD) may include a sensor (e.g., K02 of FIG. 25), and the volume of the airflow generated by the airflow generating device (or APG device) (K00) may be adjusted according to the detection result of the sensor (K02). In one embodiment, the sensor (K02) may be a humidity/temperature sensor, and the volume of the airflow generated by the airflow generating device (or APG device) (K00) may be adjusted according to the detection result of the sensor (K02), but is not limited thereto. It should be noted that the position of the sensor (K02) within the host device (25HD) may be optimized according to actual requirements, and is not limited thereto.

The user can manually control the wearable sound device to change/adjust the intensity/volume of the airflow; alternatively, the airflow generating device (K00) can be triggered/activated in response to an instruction signal from a sensor disposed within the host device (25HD) or communicatively coupled to the airflow generating device (K00) via a wired/wireless connection. The intensity/volume of the airflow can be adjusted via the amplitude of the demodulation (driving) signal (e.g., ±SV) and/or the modulation (driving) signal (e.g., SM).

APG devices (e.g. K00) that generate air pulses of constant amplitude are designed to have low power consumption by utilizing energy recycling as described above.

In short, in applications where audio is not required, the host device (25HD) (operating in blower mode) may or may not be powered by batteries, and the air pulse (AP) still generates a continuous net air movement in one direction to dry the ear canal (or dissipate heat previously generated by the host device (25HD)). Unlike traditional speaker technologies such as electrodynamic or electrostatic which lack the ability to move air in one (single) direction, the APG device or airflow generating device (e.g., K00) of the present invention capable of unidirectional airflow provides a solution for ventilation.

Details or variations of circuits for wearable sound devices, sound generating devices, APG devices, and energy recycling are disclosed in U.S. Application Serial Nos. 62/572,405, 62/575,672, 62/579,088, 62/579,914, and 63/437,371, the disclosures of which are incorporated herein by reference in their entireties.

In summary, the air pulse generator of the present invention generates asymmetric air pulses at an ultrasonic pulse rate and can function as an air pump. Multiple air pulses continuously generate a net airflow in a single direction, which can be applied to air movement applications such as cooling, drying, dehumidification, heat dissipation, and/or ventilation.

Those skilled in the art will readily recognize that various modifications and variations of the devices and methods can be made while maintaining the teachings of the present invention. Therefore, the above disclosure should be construed as limited only by the metric and bounds of the appended claims.

Claims (30)

As an air pulse generator,
A film structure configured to be actuated to generate a plurality of air pulses at an ultrasonic pulse rate, said film structure comprising a pair of flaps.
Including,
The above pair of flaps is driven to perform common mode movement to form an ultrasonic pressure change at the ultrasonic carrier frequency,
The above pair of flaps is driven to perform differential mode movement to form an opening at a rate synchronized with the ultrasonic carrier frequency,
An air pulse generator, wherein the plurality of air pulses generate a net airflow in one single direction. In the first paragraph,
An air pulse generating device, wherein the flap pair comprises a first flap and a second flap arranged opposite to each other. In the first paragraph,
The above film structure is actuated by a driving signal,
An air pulse generator, wherein the above driving signal is generated according to an input signal including a nonzero DC (direct current) offset. In the third paragraph,
The plurality of air pulses generate a first net airflow in a first direction in response to the DC offset being positive,
The plurality of air pulses generate a second net airflow in a second direction in response to the DC offset being negative,
An air pulse generating device wherein the first direction and the second direction are opposite to each other. In the first paragraph,
The above film structure is actuated by a modulation signal to perform the common mode shift,
An air pulse generator, wherein the above modulation signal is generated according to an input signal including a non-zero DC offset. In the first paragraph,
An air pulse generator, wherein the film structure is actuated by a demodulation signal to perform the differential mode movement. In the first paragraph,
An air pulse generator, wherein the direction of the net air flow generated by the air pulse generator is determined by the phase between the modulation signal and the demodulation signal. In the first paragraph,
The above air pulse generator is an air pulse generator that functions as an air pump. In the first paragraph,
An air pulse generating device, wherein the air pulse generating device is positioned above, below, or next to a heat source and is configured to dissipate heat from the heat source. In the first paragraph,
The above air pulse generating device is an air pulse generating device configured for ventilation. In the first paragraph,
An air pulse generating device, wherein the air pulse generating device is arranged within a wearable sound device and configured to ventilate the external auditory canal. In the first paragraph,
An air pulse generating device, wherein the air pulse generating device is disposed inside a host device and configured to ventilate a space within the host device. As a heat dissipation method,
A step of placing the air pulse generator of the first paragraph above, below, or next to the heat source.
A heat dissipation method comprising: As a ventilation method,
A step of placing the air pulse generating device of the first clause within the host device.
A ventilation method including: As a method of ventilation of the external auditory canal,
A step of placing the air pulse generating device of the first clause within a wearable sound device.
A method of ventilation of the external auditory canal including: As a method of detecting air quality,
A step of placing the air pulse generating device of the first paragraph within the air quality detection device.
A method for detecting air quality including: As a wearable sound device,
Housing; and
Air pulse generator according to Article 1
A wearable sound device comprising: In Article 17,
A wearable sound device, wherein the air pulse generating device generates the air flow toward the external auditory canal or outside the external auditory canal when the user wears the wearable sound device. In Article 17,
The above film structure is actuated by a driving signal,
A wearable sound device, wherein the above driving signal is generated according to an input signal including a non-zero DC (direct current) offset. In Article 17,
sensor
Including more,
A wearable sound device, wherein the volume of the air flow generated by the air pulse generator is adjusted according to the detection results of the sensor. As a fanless blower,
A film structure comprising a pair of flaps, wherein the pair of flaps is driven to perform common mode movement to form an ultrasonic pressure change at an ultrasonic carrier frequency, and the pair of flaps is driven to perform differential mode movement to form an opening at a rate synchronized with the ultrasonic carrier frequency.
Including,
The above fanless blower generates multiple air pulses according to pressure changes, and the multiple air pulses are asymmetrical.
A fanless blower wherein a plurality of air pulses generated by the fanless blower constitute a net air movement or net airflow in one direction. In Article 21,
The fanless blower is a fanless blower disposed within a host device that includes a vent. In Article 21,
The above fanless blower is a fanless blower that simultaneously produces audio sound and directional airflow. In Article 21,
The above plurality of air pulses are generated according to the input audio signal,
The above input audio signal is a fanless blower containing a non-zero direct current (DC) offset. In Article 21,
A fanless blower wherein the volume of airflow generated by the fanless blower is controlled in response to the output of a humidity sensor. In Article 21,
The above pair of flaps includes a first flap and a second flap,
The above first flap is driven by a demodulation drive signal or a modulation drive signal,
A fanless blower, wherein the volume of airflow generated by the fanless blower is adjusted through the amplitude of the demodulation drive signal or the modulation drive signal. As a method of generating air current,
A step of generating a plurality of asymmetric air pulses at an ultrasonic pulse rate by an air pulse generator.
Including,
The above multiple asymmetric air pulses generate a net airflow in a single direction,
The step of generating the above plurality of asymmetric air pulses is:
A step of driving a pair of flaps of the air pulse generator to perform common mode movement to form an ultrasonic pressure change at an ultrasonic carrier frequency; and
A step of driving a pair of flaps of the air pulse generator to perform differential mode movement to form an opening at a rate synchronized with the ultrasonic carrier frequency.
A method for generating an air flow of the air pulse generator, comprising: In Article 27,
A step of driving the film structure of the air pulse generator through a driving signal.
Including,
A method for generating an airflow, wherein the driving signal is generated according to an input signal, and the input signal includes a non-zero direct current (DC) offset. In Article 27,
A step of performing the common mode shift by driving the film structure of the air pulse generator through a modulation driving signal.
Including,
A method for generating an air current, wherein the above modulation driving signal is generated according to an input signal, and the input signal includes a non-zero direct current (DC) offset. In Article 27,
A step of performing the differential mode movement by driving the film structure of the air pulse generator through a demodulation driving signal.
A method of generating an airflow, comprising: