Air pulse generator with tooth edge pattern slits

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 specifically, to an air pulse generator capable of generating asymmetric air pressure pulses. [Background technology]

[0002] Traditionally, speaker drivers and back enclosures have been two major design challenges in the speaker industry. It is difficult for a single conventional speaker (such as a dynamic driver) to cover the entire audio frequency range (e.g., 20Hz to 20kHz). To produce high-fidelity sound at sufficiently high sound pressure levels (SPL), both the radiation / movement surface of the conventional speaker and the volume / size of the back enclosure must be sufficiently large.

[0003] U.S. Patents 9,736,595 and 10,367,430 discuss ultrasonic pulses for acoustic generation applications. Furthermore, to address the bandwidth and size issues mentioned above, the applicant discloses APG (Air Pulse Generator) devices or APPS (Air Pressure Pulse Speakers) in U.S. Patents 10,425,732, 11,172,310, 10,425,732, 11,043,197 and 11,445,279.

[0004] However, the performance of APPS depends on the asymmetry of the pneumatic pulses generated by the APG device. [Overview of the project]

[0005] Therefore, the main objective of this application is to provide an APG device capable of generating asymmetric pneumatic pulses and to improve upon the shortcomings of the prior art.

[0006] One embodiment of the present disclosure provides an air pulse generator comprising a film structure including a first flap and a second flap facing each other. The film structure is operated to operate at an ultrasonic frequency, and the air pulse generator generates a plurality of air pulses at an ultrasonic pulse velocity. The first and second flaps are operated to perform differential motion to form an opening or virtual valve. A slit is formed between the first and second flaps, and the slit forms an opening or virtual valve. The slit is formed as a zigzag pattern on the film structure.

[0007] These and other objectives of the present invention will undoubtedly become clear to those skilled in the art upon reading the following detailed description of preferred embodiments shown in various figures and drawings. [Brief explanation of the drawing]

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

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

[0010] The air pulse generator of the present invention generally includes a pair of opposing flaps manufactured by etching a film layer made of, for example, SOI (Silicon-on-Insulator), POI (Poly-on-Insulator), or other suitable material. By adding a layer of piezoelectric material such as PZT deposited on the pair of flaps, the pair of opposing flaps are made to move up and down, generating both common-mode motion and differential-mode motion, which perform modulation and demodulation functions, respectively.

[0011] In particular, Figure 1 is a cross-sectional view of an air pulse generator (APG) device 100. The APG device includes a film structure (e.g., a membrane or diaphragm) 10. The film structure 10 includes flaps 101 and 103 that face each other. The operating principle of the APG device 100 is similar to that disclosed in U.S. Patent No. 11,943,585B2. The flaps 101 and 103 (formed as a flap pair 102) are actuated to perform common-mode motion, forming an amplitude-modulated ultrasonic pneumatic pressure change at an ultrasonic frequency (e.g., 192 kHz), which can be considered a modulation operation. On the other hand, the flaps 101 and 103 are also actuated to perform differential motion, forming an opening 112 or virtual valve (abbreviated as VV) 112 at an ultrasonic opening speed (e.g., 192 kHz) to perform a demodulation 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 specific wiring configurations. For example, as shown in Figure 2, the APG device 100 may include an actuator 101A located on flap 101 and an actuator 103A located on flap 103. Actuators 101A and 103A include upper and lower electrodes. In one embodiment, the lower electrodes of actuators 101A and 103A receive a common modulation signal SM, and the upper electrodes of actuators 101A and 103A receive differential demodulation signals +SV and -SV, where the demodulation signals +SV and -SV have opposite polarities. Note that the wiring configuration shown in Figure 2 is illustrative and not limiting. As long as one electrode of actuator 101A / 103A receives a modulated signal SM and the other electrode receives a demodulated signal SV (representing either +SV or -SV), the requirements of the present invention are satisfied, and this falls within the scope of the present application.

[0013] The waveforms of the modulated signal SM and the demodulated signal ±SV can be seen in Figure 3 (or something similar to that shown in Figure 3). Note that the demodulation frequency of the demodulated signal SV is half the modulation frequency of the modulated signal SM. For example, if the modulation frequency of the modulated signal SM is 192 kHz, the demodulation frequency of the demodulated signal SV will be 96 kHz. Thus, the flaps 101 and 103 form an opening 112 at an opening velocity of 192 kHz, and the APG device 100 uses an ultrasonic pulse velocity f of 192 kHz. Pulse This generates multiple air pulses.

[0014] In this application, "flaps 101 and 103 perform common-mode motion" means that flaps 101 and 103 are operated to move in a common direction or are operated by a common drive signal, and "flaps 101 and 103 perform differential-mode motion" means that flaps 101 and 103 are operated to move / bend in different / opposite directions relative to a common position or are operated by a differential signal pair.

[0015] A slit 112 is formed between flap 101 and flap 103. In this application, “slit,” “opening,” and “virtual valve” share the same notation (e.g., 112) because they share the same location and represent similar concepts in different embodiments. By driving flaps 101 and 103 via demodulated signals ±SV, the distance between the free end of flap 101 and the free end of flap 103 is increased, forming opening 112 or VV112. The upper part of Figure 1 shows a snapshot of VV112 being closed / sealed, and the lower part of Figure 1 shows a snapshot of VV112 being opened.

[0016] The pattern of the slits 112 on / over the film structure 10 is not limited. Intuitively, the slits 112 may have a linear slit pattern. Figures 4A to 4C show schematic diagrams of an APG apparatus having a linear slit pattern. As shown in Figure 4B, the slits 112 having a linear slit pattern can be considered to include a zero projection into the X direction / dimension. An APG apparatus having a linear slit pattern has been successful in generating asymmetric airflow pulses. However, the asymmetry of the pneumatic pulses generated by an APG apparatus having a linear slit pattern is not so obvious, or may even be unmeasurable. This is because, as shown in Figure 4C, the airflow around VV112 is so congested that the airflow bypasses it before reaching VV112. Figure 4C schematically shows the airflow vectors around VV112. In some of the figures of this application, different types of shading are used to show the flaps 101 and 103, but this does not mean that the flaps 101 and 103 are made of different materials.

[0017] Due to airflow congestion (when VV112 is (just) "open"), the pressure difference ΔP around VV112 increases. Here, ΔP = P A -P B And P A / P BThis represents the air pressure directly above / below the plane defined by flaps 101 / 103. Ideally, when VV is open, the pressure difference ΔP should be neutralized as quickly as possible. However, the neutralization of the pressure difference ΔP corresponding to the slits in the linear pattern is not sufficiently fast. This is due to the lateral component of the airflow and airflow bypass.

[0018] As shown in Figure 4, the airflow vector consists of a strong lateral component (a component other than the Z direction; in the linear slit pattern shown in Figure 4B, the lateral component represents the component parallel to the X direction), which means that the airflow is bypassing. This bypassing of the airflow not only lengthens the airflow path but also slows down the response of the pressure balance on both sides of flaps 101 and 103. After reaching the vicinity of VV112, the air lines up and waits in turn to be pushed out through the narrow opening of VV112. All these steps / factors lead to their respective low-pass filter (LPF) effects. When these factors are combined, a powerful higher-order LPF is formed, f Pulse The harmonics are filtered out. A strongly asymmetric waveform means that the spectral components of the harmonics are strong, so f Pulse Such removal of harmonics means mitigating asymmetry.

[0019] The asymmetry of pneumatic pulses is important for the performance of APG devices in both acoustic generation applications (which can be considered as AC (alternating current) airflow) and air transport applications (which can be considered as DC (direct current) airflow). It is desirable to propose newer APG designs that incorporate pneumatic pulse asymmetry.

[0020] The following are some guidelines. To avoid overcrowding of the air flow, VV needs to be designed to spread over a significant range in the X direction / dimension (or at least include a non-zero projection onto the X direction / dimension). In other words, VV needs to cover a significant proportion (or occupy a significant area) of the total area of flaps 101, 103. For example, VV112 covers / occupies 20 - 40% (or at least 15%) of the total area of flaps 101, 103, but is not limited thereto.

[0021] Furthermore, in order to minimize the lateral component when VV is "open", the acoustic impedance of VV needs to be distributed approximately evenly in the X direction so that air flows straight through VV (mainly through the Z direction). The amplitude of the combined common mode displacement U Z.COM (x) is recommended to be distributed approximately evenly in the X direction. U Z.COM (x) is a combination / set of the common mode displacements of 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)) and can be expressed as such. Here, ΔU Z,101 (x) / ΔU Z,103 (x) represents the individual common mode displacements of flaps 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 airflow congestion and minimize the lateral component is to pattern / form slits in a zigzag pattern on the film structure. In this application, a zigzag patterned slit may mean that the slit has a non-zero projection in the X direction / dimension in the top perspective view, assuming that 1) the slit is not straight, 2) the slit changes direction in the forward and backward directions, or 3) the slit is patterned in a zigzag pattern in the forward and backward directions between the X directions and extends toward the Y direction. The projection of the zigzag patterned slit in the X direction / dimension may have a length / depth that is a significant proportion (e.g., 15% or more) of the distance between the flaps 101 and 103 or the anchors of the APG device.

[0023] Please refer to Figures 5A to 5D. Figures 5A to 5D show an APG device 200 according to one embodiment of the present invention, Figure 5C shows a top perspective view of (part of) the zigzag pattern of the slit 212, 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 VV212 is closed), and Figure 5D schematically shows the airflow vector when VV212 with a zigzag pattern is open along line D-D' in Figure 5C.

[0024] The width (Y-direction dimension / size) of the APG device 200 is not limited to that shown in Figure 5C. The APG device 200 may include a wide cantilever beam. In other words, the width of the APG device 200 may be several times greater than the length (X-direction dimension / size) of the APG device 200. Alternatively, in one embodiment, the flaps 101 and 103 may extend in the Y-direction and have relatively extreme aspect ratios (e.g., greater than 2 or less than 1 / 2), but are not limited thereto.

[0025] The slit 212 may have a toothed edge pattern. Specifically, Figure 6 shows a flap 101 that is far from flap 103, which has a toothed edge pattern. As shown in Figure 6, flaps 101 / 103 include projections 220 / 240 and recesses 222 / 242. The projections 220 and recesses 240 are arranged alternately with respect to each other. When flaps 101 and 103 are separated only by the slit 212 (see Figures 5C and 6), the recesses 242 of flap 103 accommodate the projections 220 of flap 101, and vice versa, with the projections 220 of flap 101 and the projections 240 of flap 103 being arranged alternately with respect to each other. Furthermore, in Figure 5C, the slit 212 has, as an example, a rectangular toothed edge pattern.

[0026] From Figure 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 to bend in a zigzag pattern back and forth in the X direction and extend toward the Y direction. Tooth depth D T , that is, x (shown in Figure 5C) 103L and x 101R The distance between them is x 101L and x 103R The distance d between anchors in that relationship AA It may be a certain percentage (for example, 15% or more, or 20-40%). Here, the flaps 101 and 103 of the APG device 200 are assumed to be fixed on an anchor structure, similar to the APG device 100, but the anchor structure is omitted in Figure 5 for simplicity.

[0027] Furthermore, the recess 222 of the flap 101 (or, if the slit width is ignored, the projection 240 of the flap 103) has a width W T It may have a width W T This also represents the length of segment 231. In Figure 5C, W T This can be considered as the width of the projection of the flap 103. In order to effectively reduce acoustic resistance, in one embodiment, the width W T is, W T >=1.5×Hslit or W T >=1.5×U Z_open (However, it is not limited to this) it can be selected such that H slit This represents the height of the opposing wall between flap 101 and flap 103, and is typically defined by the thickness of the film structure, U Z_open This represents the displacement difference between the free end of flap 101 and the free end of flap 103 in the Z direction when VV212 is open. T >=H slit or W T >=U Z_open As long as this is the case, the requirements of this application are met and it falls within the scope of this application.

[0028] Length W T The line segment 231 indicates that the projection of flap 103 has a flat upper part (also denoted as 231), and the recess of flap 101 has a flat bottom part (also denoted as 231). The flat upper part of the projection of flap 101 / 103 is advantageous in reducing acoustic resistance (compared to the case of a projection with a sharp tip), and the flat bottom of flap 101 / 103 is advantageous in increasing the effect of lengthening the slit to reduce inter-tooth acoustic resistance (compared to the case where the recess has a recessed sharp tip). In general, compared to sawtooth / sinusoidal patterned slits, the slit may be patterned such that the projection of flap 101 / 103 has a flat part (e.g., 231) for the reason of reducing acoustic resistance.

[0029] Note that slit 212 in Figure 5C includes a non-zero projection into the X direction / dimension, i.e., line segment 232. In comparison, slit 112 in Figure 4B is considered to have a zero projection into the X direction / dimension, geometrically or in the top perspective view. Furthermore, slit 212 is longer than slit 112.

[0030] When flaps 101 and 103 are operated to perform differential motion, the slit 212 is lengthened, and due to the fact that the slit 212 includes a non-zero projection into the X direction / dimension, the acoustic impedance and lateral airflow components are significantly reduced. The airflow is x 103L and x 101R The air flows through the region between the two. Furthermore, as can be seen from Figure 5D, the direction of the airflow can 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] Figures 7 and 8 show the time sequences of common-mode displacement and differential-mode displacement, respectively, where t CYC indicates the cycle time. In one embodiment, t CYC = 1 / f Pulse These two time sequences may not actually exist independently (for example, in time-division operation) and are coupled by the wiring configuration shown in Figure 2 to one movement of flap 101 and another movement of flap 103; therefore, they are for illustrative purposes only. For further details, see Japanese Patent No. 11,943,585B2 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 semi-transparent," and "unpressurized." In other words, this is (n+1 / 8)·t CYC ~(n+3 / 8)·t CYC During this period, the common-mode movement of flaps 101 and 103 will have a minimum ΔP, meaning that the common-mode movement of flaps 101 and 103 will effectively "disappear".

[0033] Conversely, (n+5 / 8)·t CYC ~(n+7 / 8)·t CYCDuring this time, VV212 is considered to be in a "closed" state, and the region enclosed by segments 131-132 is considered to be "non-porous," "acoustically opaque," and "pressurized." In other words, flaps 101 and 103 are this (n+5 / 8)·t CYC ~(n+7 / 8)·t CYC During this period, it can be treated as a continuous membrane, meaning that it behaves like one (a complete membrane) with respect to membrane movement and membrane acceleration.

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

[0035] Figures 9A and 9B repeatedly show the common-mode motion and differential-mode motion of the APG device 200, respectively. Furthermore, Figure 9A shows the combined 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 Figure 9B shows the acoustic conductance 1 / Z with respect to x when both flaps are operating in differential mode. VV This shows that Z VV This represents the acoustic impedance of VV.

[0036] From Figure 9A, the composite common mode displacement U corresponding to VV212 Z.COM (x) is compared to the one corresponding to VV112, 103L and x 101R It can be seen that the acoustic impedance Z is evenly distributed across the X dimension between and . VV is, x 103L and x 101R Low within the range between x 103L and x 101R It can be seen that the distribution is approximately uniform across the X dimension between and . It can be concluded that APG devices including zigzag slits (e.g., slit 212) succeed in avoiding airflow congestion, minimizing the lateral component, and thereby producing asymmetric pneumatic pulses.

[0037] Furthermore, the "extinction" period or VV release period (for example, (n+1 / 8)·t in Figure 8) CYC ~(n+3 / 8)·t CYC ) is as shown in Figure 10A, effective displacement U Z.COM (t) needs to be properly synchronized and aligned. Considering the "disappearance" period, the physical displacement U Z.COM (t) is a series of virtual / effective motion UVs, as shown in Figure 10B. Z.COM This can be converted or considered in the case of sound generation applications or APPS (APS: pneumatic pulse speaker) applications, such as asymmetric virtual moving UV Z.COM This can be used, for example, to generate asymmetric pressure pulses via chamber compression.

[0038] For example, see Figure 11, which shows a schematic diagram of the APG apparatus 300. The APG apparatus 300 includes a VV312 (a zigzag slit, which may be, for example, a VV212) and a cap 320, which is used to form a compression chamber 315. According to the timing diagram in Figure 10A, the compression of the chamber produces asymmetrical "virtual / effective motion" UV, as shown in Figure 10B. Z.COMPressure pulses are generated in response to each segment of (t), resulting in a pressure change at outlet 313. Due to the pressure change, sound waves propagate radially at the speed of sound, forming a chain of acoustic pressure pulses.

[0039] Note that the pressure pulse generated in chamber 315 when VV312 is in the "closed" state, and the magnitude of the pressure pulse, are determined by the common mode displacement of flaps 101, 103 when VV312 is in the "closed" state. Conversely, the airflow passing through the plates of flaps 101, 103 during the period when VV312 / 212 is in the "open" state is a widely and uniformly dispersed airflow (above VV312 / 512), with a minimal airflow over-density, a low acoustic impedance above VV312 / 212, and a straight and short airflow path, which generates a relatively small ΔP. Therefore, it has only a slight impact on the net pneumatic pulse generated by device 300.

[0040] Refer to FIG. 12. Another view of the interaction between this common mode and differential mode is shown, which can be applied to the (indirect) pressure pulse generation method using a compression chamber. The movement of the differential mode is represented by the "porosity" value shown in FIG. 10A. Time (n + 1 / 8)·t CYC ~(n + 3 / 8)·t CYC During the period between (shown in FIG. 8), VV212 becomes in the "high porosity" state, and the ΔP formed by the common mode movement mainly "leaks" through the porous surface. As a result, during the period from (n + 1 / 8)·t CYC ~(n + 3 / 8)·t CYC ΔP becomes zero or approximately zero. Thus, the ΔP due to the compression of the chamber is dominated by the "virtual / effective displacement" that occurs during the period from (n + 5 / 8)·t CYC ~(n + 7 / 8)·t CYC as shown in FIG. 10B.

[0041] Several design criteria regarding the efficiency of bypassing airflow over-density 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.

Equation

[0042] In formula (1), A(VV) refers to the area occupied by the slit (e.g., zigzag slit 212), and A(101 + 103) refers to the total area of flaps 101 and 103. Assuming that the perimeter of the film structure is rectangular, ACR can be further expressed as follows [Number]

[0043] In the present application, particularly in formulas (2) and (3), x 101L / x 103L refers to the leftmost position on the X-axis of flap 101 / 103, and x 101R / x 103R refers to the rightmost position on the X-axis of flap 101 / 103. From another perspective, assuming that the perimeter of the film structure is rectangular, x 101L / x 103R refers to the position on the X-axis where flap 101 / 103 is fixed, and x 103L [[ID=...]]​​​​​​​​​​​​​​​​​​​​2 U Z.COM (t) / dt 2 By "eliminating" a portion of it, the highly asymmetrical "virtual acceleration" of flaps 101 and 103 d 2 UV Z.COM (t) / dt 2 Generates.

[0047] In the direct pulse generation method, an asymmetrical "virtual acceleration" d 2 UV Z.COM (t) / dt 2 A pressure pulse is generated according to each segment. For example, as shown in Figure 13A, the pressure pulse is U Z.COM (t) is generated in response to the common mode displacement of the negative half-cycle, thereby generating positive d 2 UV Z.COM (t) / dt 2 A positive half-cycle acoustic output is generated through this process. In this case, since pressure is related to acceleration and acceleration is the second derivative of displacement, the pneumatic pulse is generated directly, compared to the indirect method in which the pneumatic pulse is generated by compression of the chamber.

[0048] The timing adjustment shown in Figure 13A is U Z.COM There is, but is not limited to, an alignment between the centers of (t) and VV (e.g., 112 or 212) between the open and closed states. For example, Figure 13B shows that the timing of the open and closed states is U Z.COM Figure 13C shows a scenario where (t) is drawn "before" U Z.COM This shows a scenario where (t) is pushed "later". Z.COM The optimal timing adjustment between (t) and the open / closed state of VV (e.g., 112 or 212) depends on the duty cycle of VV or the amount of 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 also have a trapezoidal tooth edge pattern. For example, in Figures 14 and 15, slits 412 and 512 have a trapezoidal tooth edge pattern. In Figure 14, the projection of the flap 101 is wider at the bottom (e.g., 401) than at the top (e.g., 402), while in Figure 15, the projection of the flap 101 is wider at the top (e.g., 502) than at the bottom (e.g., 501). Both cases and their variations (e.g., fillets or chamfers can be formed on the corners of the projections of the rectangular / trapezoidal slits) are within the scope of the present invention.

[0050] Furthermore, the APG device of the present invention can be applied to sound generation applications as an APPS (Air Pressure Pulse Speaker), and the multiple generated air pulses are amplitude modulated, and the envelope (or modulated signal SM) of the multiple air pulses is generated from the input signal S. IN (See Figure 3) is either an AC (alternating current) component or contains an AC component, resulting in, for example, an AC airflow. Input signal S IN This may be an audio signal or may contain an audio signal. The APG / APPS of the present invention can be placed in or applied to wearable sound devices such as earbuds, earphones, TWS (True Wireless Stereo), headphones, and hearing aids. The APG / APPS of the present invention can also function as a loudspeaker or open field speaker, which can be placed in, but is not limited to, OWS (Open Wearable Stereo), telephones (as receivers or speakers), tablets, laptops, desktop (game / recording) monitors, televisions, or AR / VR (Augmented Reality, Virtual Reality) devices.

[0051] Furthermore, the APG device of the present invention can be applied to air transport applications that include functions similar to those of fans, blowers, etc. Multiple generated air pulses (or a modulated signal SM) are generated from an input signal S. INThe envelope of the input signal S is either DC (direct current) or contains a DC component, which can result in, for example, a DC airflow. IN This is a DC signal or may include a DC signal. The APG device for air transport applications of the present invention can be used for heat dissipation, ventilation, cooling, drying, or sensing air quality, but is not limited to these. The APG device for air transport applications is described in detail in U.S. Patent Application No. 18 / 624,105, but is not described here for brevity.

[0052] In short, the present invention enhances the performance of an APG device by increasing the asymmetry of the air pulse using a zigzag slit or a slit including a toothed edge.

[0053] Those skilled in the art will readily understand that numerous changes and modifications can be made to the apparatus and method while maintaining the teachings of the present invention. Accordingly, the above disclosure should be construed as being limited only by the appended claims and boundaries.

Claims

1. An air pulse generator, said air pulse generator, The film structure includes a first flap and a second flap that face each other, The film structure is operated to operate at ultrasonic frequencies, and the air pulse generator generates multiple air pulses at ultrasonic pulse speeds. The first flap and the second flap are operated to perform differential motion, forming an opening or a virtual valve. A slit is formed between the first flap and the second flap, and the slit forms the opening or the virtual valve. The slits are formed as a zigzag pattern on the film structure, The slit bends in a zigzag pattern back and forth in a first direction along the axis connecting the fixed end of the first flap and the fixed end of the second flap, and extends toward a second direction, and the slit separates the first flap and the second flap. Air pulse generator.

2. The air pulse generator according to claim 1, wherein the slit includes a non-zero projection in the first direction.

3. The first flap includes a plurality of first protrusions, and the second flap includes a plurality of second protrusions. The air pulse generator according to claim 1, wherein the first projection and the second projection are arranged alternately with respect to each other.

4. The first flap includes a plurality of first recesses, and the second flap includes a plurality of second recesses. The air pulse generator according to claim 3, wherein the first projections and the first recesses are arranged alternately with respect to each other.

5. The first flap includes a plurality of first protrusions, The air pulse generator according to claim 1, wherein one of the first protrusions includes a flat portion.

6. The first flap includes a plurality of first protrusions, One of the first projections corresponds to the width, The air pulse generator according to claim 1, wherein the width is greater than the height of the wall between the first flap and the second flap.

7. The first flap includes a plurality of first protrusions, One of the first projections corresponds to the width, The air pulse generator according to claim 1, wherein the width is greater than the difference in displacement between the free end of the first flap and the free end of the second flap when the virtual valve is opened.

8. The first flap includes a plurality of first protrusions, One of the first projections corresponds to the depth, The air pulse generator according to claim 1, wherein the depth is greater than 15% of the distance between the anchors.

9. The air pulse generator according to claim 1, wherein the slit forms a tooth edge pattern.

10. The air pulse generator according to claim 1, wherein the slit forms a rectangular tooth edge pattern.

11. The air pulse generator according to claim 1, wherein the slit forms a trapezoidal tooth edge pattern.

12. The air pulse generator according to claim 1, wherein the film structure is operated to perform common-mode motion and forms ultrasonic air pressure changes that are amplitude-modulated with an ultrasonic frequency.

13. The air pulse generator according to claim 12, wherein the first flap and the second flap are operated to perform the common mode motion and the differential motion simultaneously.

14. The air pulse generator according to claim 1, wherein the first flap and the second flap are operated to perform the differential motion to form the opening at an ultrasonic opening velocity.

15. When the difference in displacement between the first flap and the second flap is less than the thickness of the film structure, the virtual valve is in a closed state. The air pulse generator according to claim 1, wherein the closed state of the virtual valve occurs during the transition of differential motion between the first flap and the second flap.

16. The air pulse generator according to claim 1, wherein the slits are formed in a zigzag pattern on the film structure such that the area coverage ratio is 0.25 or more.

17. The air pulse generator according to claim 1, wherein the slits are formed in a zigzag pattern on the film structure such that the displacement coverage ratio is 0.5 or more.

18. The first flap and the second flap form a flap pair. The time during which the virtual valve is closed is adjusted to the time corresponding to the common mode motion of the flap pair moving in a third direction. The air pulse generator according to claim 1, wherein the time for which the virtual valve is open is adjusted to a time corresponding to the common mode motion of the flap pair moving in a fourth direction opposite to the third direction.

19. Including the cover structure, The air pulse generator according to claim 1, wherein a chamber is formed between the film structure and the cover structure.

20. An orifice is formed in the cover structure, The air pulse generator according to claim 19, wherein the plurality of air pulses propagate outward through the orifice.

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

22. The air pulse generator according to claim 1, wherein the combined common mode displacement corresponding to the virtual valve is evenly distributed within the range between the free end of the right end of the first flap and the free end of the left end of the second flap.

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

24. The air pulse generator described in claim 1 is applicable to sound generation applications.

25. The air pulse generator described in claim 1 is applicable to air transport applications.

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