Air-pulse generating device with tooth edge patterned slit

Abstract

To provide an APG device capable of producing asymmetric air pressure pulses.SOLUTION: An air-pulse generating device includes a film structure including a first flap and a second flap opposite to each other. The film structure is actuated to operate at an ultrasonic frequency, and the air-pulse generating device produces a plurality of air pulses at an ultrasonic pulse rate. The first flap and the second flap are actuated to perform a differential movement to form an opening or a virtual valve. A slit is formed between the first flap and the second flap, and the opening or the virtual valve is formed because of the slit. The slit is formed as a zigzagging pattern on the film structure.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an air pulse generator, and more particularly to an air pulse generator capable of generating asymmetric air pressure pulses. [Background technology]

[0002] Traditionally, speaker driver and back enclosure are two major design challenges in the speaker industry. It is difficult for one traditional speaker (such as a dynamic driver) to cover the entire audio frequency range (e.g., 20Hz-20KHz). To produce high-fidelity sound at a sufficiently high sound pressure level (SPL), both the radiating / moving surface of the traditional speaker and the volume / size of the back enclosure need to be large enough.

[0003] US Patent Nos. 9,736,595 and 10,367,430 discuss ultrasonic pulses for sound generation applications.Furthermore, applicants have disclosed APG (Air Pulse Generator) devices, or APPS (Air Pressure Pulse Speaker) in US Patent Nos. 10,425,732, 11,172,310, 10,425,732, 11,043,197, and 11,445,279 to solve the above bandwidth and size problems.

[0004] However, the performance of APPS depends on the asymmetry of the air pressure pulses generated by the APG device. Summary of the Invention

[0005] Therefore, the main objective of the present application is to provide an APG device capable of generating asymmetric air pressure pulses, thereby remedying the shortcomings of the prior art.

[0006] One embodiment of the present disclosure provides an air pulse generator, the air pulse generator including a film structure including a first flap and a second flap opposed to each other. The film structure is actuated to operate at an ultrasonic frequency, and the air pulse generator generates a plurality of air pulses at an ultrasonic pulse rate. The first flap and the second flap are actuated to perform differential motion to form an opening or virtual valve. Slits are formed between the first flap and the second flap, the slits forming the opening or virtual valve. The slits are formed in a zigzag pattern on the film structure.

[0007] These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of an air pulse generator (APG). [Diagram 2] This is a wiring diagram of the APG device. [Diagram 3] FIG. 2 is a diagram showing a modulated signal and a demodulated signal. [Figure 4A] FIG. 2 is a cross-sectional view of an APG device. [Figure 4B] FIG. 4B is a top view of the APG device of FIG. 4A. [Figure 4C] FIG. 4C shows the direction of airflow when the virtual valve (VV) of the APG device of FIG. 4B is opened. [Figure 5A] FIG. 1 is a cross-sectional view of an APG device according to an embodiment of the present application. [Figure 5B] FIG. 1 is a cross-sectional view of an APG device according to an embodiment of the present application. [Figure 5C] FIG. 5C is a top view of the APG device of FIGS. 5A and 5B. [Figure 5D] FIG. 5D shows the direction of airflow when the virtual valve (VV) of the APG device of FIG. 5C is opened. [Figure 6] FIG. 5B illustrates the separated first and second flaps of the APG device of FIG. 5A. [Figure 7] FIG. 5D illustrates common mode motion of the first and second flaps of the APG device of FIG. 5C. [Figure 8] 5D illustrates a differential mode motion of the first and second flaps of the APG device of FIG. 5C. FIG. [Figure 9A] FIG. 6 illustrates the resultant common mode displacement of the common mode motion and acoustic conductivity of the differential mode motion of the APG devices of FIGS. 4 and 5. [Figure 9B] FIG. 6 illustrates the resultant common mode displacement of the common mode motion and acoustic conductivity of the differential mode motion of the APG devices of FIGS. 4 and 5. [Figure 10A] FIG. 5D illustrates the resultant common mode displacement versus porosity of the APG device of FIG. 5C in accordance with an embodiment of the present application. [Figure 10B] FIG. 5D illustrates virtual / effective common mode displacement versus porosity for the APG device of FIG. 5C in accordance with an embodiment of the present application. [Figure 11] FIG. 1 illustrates an APG device according to an embodiment of the present application. [Figure 12] FIG. 2 illustrates common mode and differential mode motion within one cycle of an APG device according to an embodiment of the present application. [Figure 13A] FIG. 1 illustrates combined common mode displacement and common mode acceleration versus porosity of an APG device according to an embodiment of the present application. [Figure 13B] FIG. 1 illustrates a graph showing the resultant common mode displacement versus porosity of an APG device according to an embodiment of the present application. [Figure 13C] FIG. 1 illustrates a graph showing the resultant common mode displacement versus porosity of an APG device according to an embodiment of the present application. [Figure 14] FIG. 1 illustrates an APG device according to an embodiment of the present application. [Figure 15] FIG. 1 illustrates an APG device according to an embodiment of the present application.

[0009] The contents of U.S. Patent No. 11,943,585 B2 and application Ser. No. 18 / 624,105 are incorporated herein by reference.

[0010] The air pulse generator of the present application generally includes a pair of opposing flaps fabricated by etching a membrane layer made of, for example, SOI (silicon on insulator), POI (poly on insulator), or other suitable material. With the addition of a layer of piezoelectric material, such as PZT, deposited on the pair of flaps, the pair of opposing flaps can be actuated to move up and down to produce both common and differential mode motion, respectively performing the functions of modulation and demodulation.

[0011] In particular, FIG. 1 is a cross-sectional view of an air pulse generator (APG) device 100. The APG device includes a film structure (e.g., membrane or diaphragm) 10. The film structure 10 includes flaps 101 and 103 facing each other. The working principle of the APG device 100 is similar to that disclosed in U.S. Pat. No. 11,943,585 B2. The flaps 101 and 103 (formed as a flap pair 102) are actuated to perform a common mode motion to form an amplitude modulated ultrasonic air pressure change at an ultrasonic frequency (e.g., 192 KHz), which can be regarded as a modulating operation. Meanwhile, the flaps 101 and 103 are also actuated to perform a differential motion to form an opening 112 or a virtual valve (VV for short) 112 at an ultrasonic opening speed (e.g., 192 KHz), which performs a demodulating operation.

[0012] In the embodiment shown in the APG device 100, differential motion (demodulation) and common mode motion (modulation) are performed simultaneously by the flap pair 102. In situ and simultaneous modulation and demodulation can be performed by a specific wiring scheme. For example, as shown in FIG. 2, the APG device 100 can include an actuator 101A disposed on the flap 101 and an actuator 103A disposed on the flap 103. The actuators 101A and 103A include upper and lower electrodes. In one embodiment, the lower electrodes of the actuators 101A and 103A receive a common modulation signal SM, and the upper electrodes of the actuators 101A and 103A receive differential demodulation signals +SV and -SV, where the demodulation signals +SV and -SV are of opposite polarity. It should be noted that the wiring scheme shown in FIG. 2 is for illustrative purposes and is not limiting. As long as one electrode of the actuator 101A / 103A receives the modulated signal SM and the other electrode receives the demodulated signal SV (representing either +SV or -SV), the requirements of the present invention are met and this is within the scope of the present application.

[0013] The waveforms of the modulated signal SM and the demodulated signals ±SV can be seen in FIG. 3 (or similar to that shown in FIG. 3). It should be noted that the demodulation frequency of the demodulated signal SV is half the modulation frequency of the modulated signal SM. For example, when the modulation frequency of the modulated signal SM is 192 KHz, the demodulation frequency of the demodulated signal SV is 96 KHz. Thus, the flaps 101 and 103 form the opening 112 with an opening speed of 192 KHz, and the APG device 100 generates an ultrasonic pulse speed f of 192 KHz. Pulse to generate multiple air pulses.

[0014] As used herein, "flaps 101 and 103 have common mode motion" means that the flaps 101 and 103 are actuated to move in a common direction or are actuated by a common drive signal, and "flaps 101 and 103 have differential mode motion" means that the flaps 101 and 103 are actuated to move / bend in different / opposite directions relative to a common position or are actuated by a differential signal pair.

[0015] A slit 112 is formed between the flap 101 and the flap 103. In this application, "slit", "opening" and "virtual valve" share the same notation (e.g., 112) since they share the same location and express similar concepts in different ways. By driving the flaps 101 and 103 via demodulated signals ±SV, the distance between the free end of the flap 101 and the free end of the flap 103 is enlarged, forming the opening 112 or VV 112. The top of FIG. 1 shows a snapshot where the VV 112 is closed / sealed, and the bottom of FIG. 1 shows a snapshot where the VV 112 is opened.

[0016] The pattern of the slits 112 on / on the film structure 10 is not limited. Intuitively, the slits 112 may have a linear slit pattern. Figures 4A-4C show schematic diagrams of an APG device with a linear slit pattern. As shown in Figure 4B, the slits 112 with a linear slit pattern can be considered as including a zero projection in the X direction / dimension. The APG device with a linear slit pattern has been successful in generating asymmetric airflow pulses. However, the asymmetry of the air pressure pulses generated by the APG device with a linear slit pattern is less obvious or even measurable. This is because the airflow around the VV 112 is highly congested, and the airflow makes a detour before reaching the VV 112, as shown in Figure 4C. Figure 4C shows the airflow vectors around the VV 112 in a schematic manner. In some figures of the present application, different kinds of shading are used to indicate the flaps 101 and 103, but this does not mean that the flaps 101 and 103 are made of different materials.

[0017] Airflow congestion (when the VV112 is (just) "open") increases the pressure difference ΔP around the VV112, where ΔP=P A -P B and P A / P Brepresents the air pressure directly above / below the plane defined by the flaps 101 / 103. Ideally, when the VV is open, the pressure difference ΔP should be neutralized as soon / fast as possible. However, the neutralization of the pressure difference ΔP corresponding to the linear pattern of slits is not fast enough. This is due to the lateral component of the airflow and the bypassing of the airflow.

[0018] As shown in Figure 4, the airflow vector is composed of a strong transverse component (a component other than Z direction; in the straight slit pattern shown in Figure 4B, the transverse component represents the component parallel to the X direction), which means the airflow will be detouring. The detouring airflow not only lengthens the airflow passage, but also slows down the reaction of the pressure balance on both sides of the flaps 101, 103. After reaching the vicinity of the VV 112, the air will queue up and wait in turn to be pushed out of the narrow opening of the VV 112. All these steps / factors lead to their own low pass filter (LPF) effect. The combination of these factors forms a strong high order LPF, which increases the f Pulse The harmonics of f are filtered out. A strongly asymmetric waveform implies a strong spectral content of harmonics, so Pulse Such elimination of the harmonics of represents a reduction in asymmetry.

[0019] The asymmetry of the air pressure pulse is important to the performance of APG devices in both sound generation applications (which can be considered as AC (alternating current) airflow) and air movement applications (which can be considered as DC (direct current) airflow). It is desirable to propose further novel APG designs that include the asymmetry of the air pressure pulse.

[0020] Here are some guidelines: To avoid overcrowding the airflow, the VV should be designed to span a significant area in the X direction / dimension (or at least include a non-zero projection into the X direction / dimension). In other words, the VV should span a significant percentage of the total area of ​​the flaps 101, 103 (or occupy a significant area). For example, but not limited to, the VV 112 spans / occupies 20-40% (or at least 15%) of the total area of ​​the flaps 101, 103.

[0021] Furthermore, to minimize the lateral components when the VV is "open", the acoustic impedance of the VV should be approximately evenly distributed in the X direction, such that air flows straight through the VV (mainly through the Z direction). The combined common mode displacement U Z.COM It is recommended that the amplitude of (x) be approximately uniformly distributed in the X direction. Z.COM (x) is the combination / set of common mode displacements of the flaps 101 and 103. For example, U Z.COM (x) is U Z.COM (x)=(w 101 (x) ΔU Z,101 (x)+w 103 (x) ΔU Z,103 (x)) / (w 101 (x)+w 103 (x)), where ΔU Z,101 (x) / ΔU Z,103 (x) represents the individual common mode displacement of the flap 101 / 103 (corresponding to the x-dimensional variable x), and w 101 (x) / w 103 (x) represents the corresponding weighting factor. In one embodiment, w 101 (x)=w 103 (x)=0.5, but is not limited to this.

[0022] One solution to avoid overcrowding of the airflow and minimize the lateral component is to pattern / form the slits on the film structure in a zigzag pattern. In this application, a zigzag patterned slit may refer to 1) the slits not being straight, 2) the slits changing direction back and forth, or 3) the slits having a non-zero projection in the X direction / dimension in a top perspective view, assuming that the slits are patterned back and forth zigzag between the X direction and extend toward the Y direction. The projection of the zigzag patterned slits in the X direction / dimension may have a length / depth that is a significant percentage (e.g., 15% or more) of the distance between the anchors of the flaps 101 and 103 or the APG device.

[0023] Please refer to Figures 5A-5D, which show an APG device 200 according to one embodiment of the present invention, Figure 5C shows (a part of) the zigzag pattern of the slits 212 in a top perspective view, Figures 5A and 5B show cross-sectional views along lines A-A' and B-B' when the flaps 101 and 103 are kept flat (or the VV 212 is closed), and Figure 5D shows a schematic of the airflow vectors when the VV 212 with the zigzag pattern is open along line D-D' in Figure 5C.

[0024] The width (dimension / size in the Y direction) of the APG device 200 is not limited to that shown in FIG. 5C. The APG device 200 may include a wide cantilever beam. That is, the width of the APG device 200 may be several times larger than the length (dimension / size in the X direction) of the APG device 200. Alternatively, in one embodiment, the flaps 101 and 103 may extend in the Y direction and have a relatively extreme aspect ratio (e.g., greater than 2 or less than ½), but is not limited thereto.

[0025] The slits 212 may have a toothed edge pattern. Specifically, FIG. 6 shows the flap 101 far from the flap 103 having a toothed edge pattern. As shown in FIG. 6, the flap 101 / 103 includes a protruding portion (protruding portion) 220 / 240 and a recessed portion (recessed portion) 222 / 242. The protruding portion 220 and the recessed portion 240 are arranged alternately with each other. When the flaps 101 and 103 are separated only by the slits 212 (see FIG. 5C and FIG. 6), the recessed portion 242 of the flap 103 accommodates the protruding portion 220 of the flap 101, and vice versa, and the protruding portion 220 of the flap 101 and the protruding portion 240 of the flap 103 are arranged alternately with each other. Furthermore, in FIG. 5C, the slits 212 have a rectangular toothed edge pattern as an example.

[0026] As can be seen from FIG. 5C, the slit 212 is not a straight line, but changes direction back and forth. The slit 212 is x 103L and x 101R It can be considered that the tooth zigzags back and forth between the X direction and extends toward the Y direction. T , i.e., (shown in FIG. 5C) x 103L and x 101R The distance between is x 101L and x 103R The distance d between the anchors AA Alternatively, the flaps 101 and 103 of the APG device 200 may be fixed onto an anchor structure (for example, 15% or more, or 20-40%). Here, the flaps 101 and 103 of the APG device 200 are assumed to be fixed onto an anchor structure similar to the APG device 100, although the anchor structure is omitted in FIG. 5 for simplicity.

[0027] Furthermore, the recess 222 of the flap 101 (or the protrusion 240 of the flap 103, ignoring the slit width) has a width W T and may have a width W T also represents the length of segment 231. T can be regarded as the width of the protrusion of the flap 103. In order to effectively reduce the acoustic resistance, in one embodiment, the width W T is W T >=1.5×Hslit Or W T >=1.5×U Z_open (but not limited to this), where H slit represents the height of the opposing wall between flaps 101 and 103, typically defined by the thickness of the film structure, and U Z_open represents the displacement difference between the free end of flap 101 and the free end of flap 103 in the Z direction when VV 212 is open. T >=H slit Or W T >=U Z_open As long as this is the case, the requirements of the present application are met and fall within the scope of the present application.

[0028] Length W T Due to line segment 231, the protrusions of the flap 103 have flat tops (also denoted as 231) and the recesses of the flap 101 have flat bottoms (also denoted as 231). Note that the flat tops of the protrusions of the flap 101 / 103 are advantageous for reducing acoustic resistance (compared to protrusions with sharp tips) and the flat bottoms of the flap 101 / 103 are advantageous for increasing the effect of increasing the slit length to reduce inter-tooth acoustic resistance (compared to recesses with concave sharp tips). In general, the slits may be patterned such that the protrusions of the flap 101 / 103 have flats (e.g., 231) for reasons of reducing acoustic resistance compared to sawtooth / sinusoidal patterned slits.

[0029] Note that slit 212 in Figure 5C includes a non-zero projection in the X direction / dimension, namely line segment 232. In comparison, slit 112 in Figure 4B can be considered to have a zero projection in the X direction / dimension, either geometrically or in a top perspective view. Additionally, slit 212 is elongated compared to slit 112.

[0030] When the flaps 101 and 103 are actuated into differential motion, the slit 212 is lengthened and the acoustic impedance and lateral airflow components are significantly reduced due to the fact that the slit 212 includes a non-zero projection into the X direction / dimension. 103L and x 101R 5D, the airflow direction may be approximately perpendicular to the XY plane, which is the plane defined by flaps 101 and 103. As a result, the pressure difference ΔP is neutralized much faster (when VV212 is open) compared to when VV112 is open.

[0031] 7 and 8 show the time sequences of common mode and differential mode displacements, respectively, where t CYC In one embodiment, t CYC =1 / f Pulse These two time sequences are for illustrative purposes only, as they may not exist alone in practice (e.g., in a time-shared operation) and are coupled to one movement of flap 101 and another movement of flap 103 by the hard-wired connection scheme shown in Figure 2. For more information, reference may be made to Patent No. 11,943,585 B2 and the references therein, which are incorporated herein by reference.

[0032] As shown in Figure 8, (n+1 / 8)·t CYC ~(n+3 / 8)·t CYC During this time, VV212 is considered to be in an "open" state, and the region enclosed by segments 231-232 is considered to be "highly porous," "acoustically translucent," and "unpressurized." CYC ~(n+3 / 8)·t CYC , the common mode motion of the flaps 101 and 103 within this period results in a minimum of ΔP, meaning that the common mode motion of the flaps 101 and 103 effectively "vanishes."

[0033] Conversely, (n+5 / 8) t CYC ~(n+7 / 8)·t CYCDuring this (n+5 / 8)·t time, the VV 212 is considered to be in a "closed" state and the area enclosed by the segments 131-132 is considered to be "non-porous", "acoustically opaque" and "pressurized". CYC ~(n+7 / 8)·t CYC can be treated as a continuous membrane during this period, which means that it behaves like one (a complete membrane) with respect to membrane motion and membrane acceleration.

[0034] As shown, when the difference in the displacement of flap 101 and flap 103 is less than (or equal to) the thickness of the film structure, i.e., ΔU Z <=H slit When VV (e.g., 112 or 212) is in a closed state, ΔU Z =|U Z,101 -U Z,103 | and U Z,101 / 103 represents the displacement of the flaps 101 / 103 in the vertical direction (Z direction / dimension). In the APG device of the present application, the closed state of the VV occurs when the differential motion of the flaps 101 and 103 transitions. In other words, during a period in which the flap 101 moves in a first direction (e.g., downward) and the flap 103 moves in a second direction (e.g., upward) opposite to the first direction, the VV is closed, and the displacement difference (ΔU Z ) is a film structure H slit This means that when the virtual valve is closed, both flaps are moving.

[0035] 9A and 9B repeatedly illustrate the common mode and differential mode motion, respectively, of the APG device 200. Furthermore, FIG. 9A illustrates the resultant common mode displacement U with respect to x, which is variable in the X dimension, when both flaps are operating in common mode. Z.COM (x), and FIG. 9B shows the acoustic conductance 1 / Z versus x when both flaps are operating in differential mode. VV where Z VV represents the acoustic impedance of VV.

[0036] From Figure 9A, the resultant common mode displacement U corresponding to VV212 Z.COM (x) is compared with its VV112 counterpart, x 103L and x 101R It can be seen that the acoustic impedance Z is evenly distributed across the X dimension between VV x 103L and x 101R Low, in the range between x 103L and x 101R It can be seen that the X-dimension between 0 and 1 is approximately evenly distributed across the X-dimension between 0 and 1. It can be concluded that an APG device including a zigzag slit (e.g., slit 212) is successful in avoiding overcrowding of the airflow and minimizing the lateral component, thereby resulting in an asymmetric air pressure pulse.

[0037] Furthermore, the “disappearance” period or the VV open period (e.g., (n+1 / 8)·t in Fig. 8) CYC ~(n+3 / 8)·t CYC ) is the effective displacement U Z.COM (t) must be properly synchronized and aligned. Considering the "disappearance" period, the physical displacement U Z.COM (t) is a set of virtual / effective motion UVs, as shown in FIG. 10B. Z.COM In the case of sound generation applications or APPS (Air Pressure Pulse Speaker) applications, such asymmetric virtual moving UV Z.COM can be utilized to generate asymmetric pressure pulses, for example via chamber compression.

[0038] For example, see Figure 11, which shows a schematic diagram of an APG device 300. The APG device 300 includes a VV 312 (which may be a zigzag slit, e.g., VV 212) and a cap 320 that is used to form a compression chamber 315. Following the timing diagram of Figure 10A, compression of the chamber creates an asymmetric "virtual / effective motion" UV Z.COMIn response to each segment of (t), a pressure pulse is generated, which creates a pressure change at the outlet 313. The pressure change causes sound waves to propagate around at the speed of sound, creating a chain of acoustic pressure pulses.

[0039] It should be noted that the pressure pulse generated in chamber 315 when VV312 is in the "closed" state and the magnitude of that pressure pulse are determined by the common mode displacement of flaps 101, 103 when VV312 is in the "closed" state. Conversely, the airflow through the plates of flaps 101, 103 during the period when VV312 / 212 is in the "open" state generates a relatively small ΔP due to the wide, evenly distributed airflow (over VV312 / 512), minimal airflow congestion, low acoustic impedance above VV312 / 212, and the straight, short airflow path, and therefore has little effect on the net air pressure pulse generated by device 300.

[0040] See Figure 12. Another view of this common mode and differential mode interaction is shown, which can be applied to the (indirect) pressure pulse generation method using a compression chamber. The differential mode behavior is represented by the "porosity" value shown in Figure 10A. Time (n+1 / 8)·t CYC ~(n+3 / 8)·t CYC During (shown in Figure 8), the VV212 is in a “highly porous” state, and the ΔP formed by the common mode motion mainly “leaks” through the porous surface, resulting in (n+1 / 8)·t CYC ~(n+3 / 8)·t CYC Thus, ΔP due to compression of the chamber is (n+5 / 8)·t CYC ~(n+7 / 8)·t CYC The displacement is governed by the "virtual / effective displacement" that occurs during the period.

[0041] Several design indices related to the efficiency of bypassing airflow congestion can be defined. In the case of a slit pattern, the area coverage ratio (ACR) and displacement coverage ratio (DCR) can be defined as follows:

number

[0042] In Equation 1, A(VV) refers to the area occupied by the slit (e.g., zigzag slit 212), and A(101+103) refers to the combined area of ​​flap 101 and flap 103. Assuming the perimeter of the film structure is rectangular, ACR can be further expressed as

number

[0043] In the present application, particularly in (Formula 2) and (Formula 3), x 101L / x 103L indicates the left end position of flap 101 / 103 on the X axis, and x 101R / x 103R refers to the position of the right end of the flap 101 / 103 on the X axis. From another perspective, assuming the perimeter of the film structure is a rectangle, x 101L / x 103R indicates the position on the X-axis where the flap 101 / 103 is fixed, and x 103L / x 101R indicates the left / right end positions on the X-axis of the protrusions of the flaps 101 / 103.

[0044] In order to effectively avoid overcrowding of airflow, it is recommended, but not limited to, ACR>=0.25 and DCR>=0.5.

[0045] The above pressure pulse generation method is called the indirect method, and Z.COM (t) or UV Z.COM The "displacement" of (t) is used to compress a small chamber (eg, 315) to generate a pressure pulse that is emitted through a narrow orifice (eg, 313).

[0046] Alternatively, the pneumatic pulses may be generated by a direct method, which conceptually uses V (e.g., 112 or 212) to generate a pulse for each pulse cycle t CYC "Acceleration" of flaps 101 and 1032 U Z.COM (t) / dt 2 By "eliminating" a portion of the flaps 101 and 103, the highly asymmetric "virtual acceleration" d 2 UV Z.COM (t) / dt 2 Generate.

[0047] In the direct pulse generation method, an asymmetric "virtual acceleration" d 2 UV Z.COM (t) / dt 2 For example, as shown in FIG. 13A, a pressure pulse is generated according to each segment of U Z.COM (t) in response to the common mode displacement of the negative half cycle of 2 UV Z.COM (t) / dt 2 A positive half cycle of acoustic output is generated through a pressure-dependent actuator, where pressure is related to acceleration, which is the second derivative of displacement, so that an air pressure pulse is generated directly, as opposed to indirectly, where an air pressure pulse is generated by compression of the chamber.

[0048] The timing adjustment shown in FIG. Z.COM 13B shows, but is not limited to, center-to-center alignment between the open and closed states of U(t) and VV (e.g., 112 or 212). Z.COM Figure 13C shows a scenario where the timing of the open and closed states is U Z.COM (t) indicates a scenario where the character is pushed "after" U Z.COM The optimum timing coordination between (t) and the open or closed state of VV (e.g., 112 or 212) will vary depending on the duty factor of VV, or the time VV is in the "closed" state. All variations of these operating conditions are within the scope of the present invention.

[0049] The zigzag slit is not limited to a rectangular tooth edge pattern. The zigzag slit may be a trapezoid tooth edge pattern. For example, in Figs. 14 and 15, slits 412 and 512 are trapezoid tooth edge patterns. The protrusions of flap 101 in Fig. 14 are wider at the bottom (e.g., 401) than at the top (e.g., 402), while the protrusions of flap 101 in Fig. 15 are wider at the top (e.g., 502) than at the bottom (e.g., 501). Both cases and variations thereof (e.g., fillets or chamfers can be formed at the corners of the protrusions of the rectangular / trapezoid pattern slits) are within the scope of the present invention.

[0050] The APG device of the present invention can be applied to sound generation applications as an APPS (air pressure pulse speaker). The generated air pulses are amplitude modulated, and the envelope of the air pulses (or the input signal S from which the modulated signal SM is generated) is generated. IN 3) may be or contain an AC (alternating current) component, resulting in, for example, an AC airflow. IN is an audio signal or can include an audio signal. The APG / APPS of the present invention can be placed or applied in a wearable sound device such as an earbud, an earphone, a TWS (TWS: true wireless stereo), a headphone, a hearing aid, etc. The APG / APPS of the present invention can also function as a loudspeaker or an open field speaker, which can be placed in, but is not limited to, an OWS (OWS: open wearable stereo), a phone (as a receiver or speaker), a tablet, a laptop, a desktop (gaming / recording) monitor, a television, or an AR / VR (AR: augmented reality, VR: virtual reality) device.

[0051] Furthermore, the APG device of the present invention can be applied to air movement applications including functions similar to fans, blowers, etc. The input signal S from which the generated air pulses (or modulating signal SM) are generated INThe envelope of the input signal S ) may be or contain a DC (direct current) component, which may result in, for example, DC currents. IN may be or include a DC signal. The APG device in air movement applications of the present invention may be used for, but is not limited to, heat dissipation, ventilation, cooling, drying, or air quality sensing. The APG device in air movement applications is described in detail in U.S. Application No. 18 / 624,105, which will not be described here for the sake of brevity.

[0052] In essence, the present invention uses zigzag slits or slits with toothed edges to increase the asymmetry of the air pulses and improve the performance of the APG device.

[0053] Those skilled in the art will readily appreciate that numerous alterations and modifications of the apparatus and method may be made while retaining the teachings of this invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

Claims

1. An air pulse generator, comprising: a film structure including a first flap and a second flap opposed to each other; the film structure is actuated to operate at an ultrasonic frequency, the air pulse generator generating a plurality of air pulses at an ultrasonic pulse rate; the first flap and the second flap are actuated to have a differential movement to form an opening or a virtual valve; a slit is formed between the first flap and the second flap, the slit forming the opening or the virtual valve; the slits are formed in a zigzag pattern on the film structure; Air pulse generator.

2. 2. The air pulse generator of claim 1, wherein the slit zigzags back and forth in a first direction and extends in a second direction.

3. 3. The air pulse generator of claim 2, wherein the slit includes a non-zero projection in the first direction.

4. the first flap includes a plurality of first protrusions and the second flap includes a plurality of second protrusions; 2. The air pulse generator of claim 1, wherein the first protrusions and the second protrusions are interleaved with one another.

5. the first flap includes a plurality of first recesses and the second flap includes a plurality of second recesses; 5. The air pulse generator of claim 4, wherein the first protrusions and the first recesses are alternately positioned with respect to one another.

6. the first flap includes a plurality of first protrusions; 2. The air pulse generator of claim 1, wherein one of said first protrusions includes a flat portion.

7. the first flap includes a plurality of first protrusions; one protrusion of the first protrusions corresponds to a width; 2. The air pulse generator of claim 1, wherein said width is greater than a height of a wall between said first flap and said second flap.

8. the first flap includes a plurality of first protrusions; one protrusion of the first protrusions corresponds to a width; 2. The air pulse generator of claim 1, wherein the width is greater than a difference in displacement between the free end of the first flap and the free end of the second flap when the virtual valve is open.

9. the first flap includes a plurality of first protrusions; one of the first protrusions corresponds to a depth; 2. The air pulse generator of claim 1, wherein the depth is greater than 15% of the distance between the anchors.

10. 2. The air pulse generator of claim 1, wherein said slits form a tooth edge pattern.

11. 2. The air pulse generator of claim 1, wherein said slits form a rectangular tooth edge pattern.

12. 2. The air pulse generator of claim 1, wherein said slits form a trapezoidal tooth edge pattern.

13. 2. The air pulse generator of claim 1, wherein said film structure is actuated into common mode motion to produce ultrasonic air pressure changes that are amplitude modulated at ultrasonic frequencies.

14. 14. The air pulse generator of claim 13, wherein the first flap and the second flap are actuated to simultaneously perform the common mode motion and the differential motion.

15. 2. The air pulse generator of claim 1, wherein the first flap and the second flap are actuated to perform the differential motion to form the opening at an ultrasonic opening speed.

16. when a difference between the displacements of the first flap and the second flap is less than a thickness of the film structure, the virtual valve is in a closed state; 2. The air pulse generator of claim 1, wherein the closed state of the virtual valve occurs upon a transition of differential motion of the first flap and the second flap.

17. 2. The air pulse generator of claim 1, wherein the slits are formed in a zigzag pattern on the film structure to provide an area coverage of 0.25 or greater.

18. 2. The air pulse generator of claim 1, wherein the slits are formed in a zigzag pattern on the film structure to provide a displacement coverage of 0.5 or greater.

19. the first flap and the second flap form a flap pair; The time at which the virtual valve is closed is adjusted to correspond to a common mode motion of the pair of flaps in a first direction; 2. The air pulse generator of claim 1, wherein the time at which the virtual valve is opened is timed to correspond to a common mode motion of the flap pair in a second direction opposite the first direction.

20. Including a cover structure, The air pulse generating device of claim 1 , wherein a chamber is formed between said film structure and said cover structure.

21. An orifice is formed in the cover structure; 21. The air pulse generator of claim 20, wherein the plurality of air pulses propagate outwardly through the orifice.

22. the first flap and the second flap form a flap pair; 2. The air pulse generator of claim 1, wherein the time at which the virtual valve is closed is adjusted to a time corresponding to a peak acceleration of the common mode motion of the flap pair.

23. 2. The air pulse generator of claim 1, wherein a resultant common mode displacement corresponding to said virtual valve is evenly distributed within a range between a rightmost free end of said first flap and a leftmost free end of said second flap.

24. 2. The air pulse generator of claim 1, wherein the acoustic impedance corresponding to the virtual valve is evenly distributed within a range between the left free end of the second flap and the right free end of the first flap.

25. The air pulse generator of claim 1 , wherein the air pulse generator is applied in sound generation applications.

26. The air pulse generator of claim 1 , wherein the air pulse generator is applied in air movement applications.

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