Gas pulse generating device

Abstract

An air pulse generating device comprises a membrane structure. The membrane structure includes a first flap and a second flap opposite to each other. The membrane structure is actuated to operate at an ultrasonic frequency, and the gas pulse generating device generates a plurality of gas pulses at an ultrasonic pulse rate. The first flap and the second flap are actuated to perform a differential mode motion to form an opening or a virtual valve. A gap is formed between the first flap and the second flap, and an opening or a virtual valve is formed by the gap. And the gap forms a back-and-forth bending pattern on the membrane structure.

Description

Technical Field

[0001] The present invention relates to a gas pulse generating device, in particular to a gas pulse generating device capable of generating asymmetric gas pressure pulses. Background Art

[0002] Traditionally, speaker actuators and rear enclosures are two major design challenges in the speaker industry. A single existing speaker (e.g., a dynamic driver) is difficult to cover the entire audio frequency band (e.g., from 20 Hz to 20 kHz). In order to produce high-fidelity sound with a sufficiently high sound pressure level, the volume or size of the radiation or moving surface and rear enclosure of the existing speaker must be large enough.

[0003] US Patent Nos. 9,736,595 and 10,367,430 describe ultrasonic pulses for vocalization applications. In addition, the applicant disclosed air pulse generator (APG) devices or air pressure pulse generator speakers (APPS) in US Patent Nos. 10,425,732, 11,172,310, 10,425,732, 11,043,197 and 11,445,279 to solve the bandwidth and size problems mentioned above.

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

[0005] Therefore, the main purpose of the present invention is to provide an APG device capable of generating asymmetric air pressure pulses to improve the deficiencies of the prior art.

[0006] An embodiment of the present invention provides an air pulse generating device, comprising a membrane structure, including a first flap and a second flap opposite to each other; wherein the membrane structure is actuated to operate at an ultrasonic frequency, and the air pulse generating device generates multiple air pulses at an ultrasonic pulse rate; wherein the first flap and the second flap are actuated to perform a differential mode motion to form an opening or a virtual valve; wherein a gap is formed between the first flap and the second flap, and the opening or the virtual valve is formed by the gap; wherein the gap forms a back-and-forth bending pattern on the membrane structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a cross-sectional schematic diagram of an air pulse generating (APG) device.

[0008] Figure 2 Shown is a wiring scheme for an APG device.

[0009] Figure 3 The modulated signal and the demodulated signal are shown.

[0010] Figure 4AA schematic cross-sectional view of an APG device is shown.

[0011] Figure 4B Show Figure 4A Schematic diagram of the top view of the APG device.

[0012] Figure 4C Show Figure 4B The direction of air flow when the virtual valve (VV) of the APG device is open.

[0013] Figure 5A and Figure 5B A cross-sectional schematic diagram of an APG device according to an embodiment of the present invention is shown.

[0014] Figure 5C Show Figure 5A and Figure 5B Schematic diagram of the top view of the APG device.

[0015] Figure 5D Show Figure 5C Airflow direction when the VV of the APG device is open.

[0016] Figure 6 Show Figure 5C A first flap and a second flap of the APG device are separated from each other.

[0017] Figure 7 Show Figure 5C Common mode motion of the first petal and the second petal of the APG device.

[0018] Figure 8 Show Figure 5C Differential mode motion of the first petal and the second petal of the APG device.

[0019] Fig. 9A and Fig. 9B The acoustic conductance of the differential mode motion and the resultant common mode displacement of the common mode motion of the APG device of FIGS. 4 and 5 are shown.

[0020] Fig. 10A The embodiment of the present invention is shown Figure 5C The relationship between the synthetic common mode displacement and the leakage degree of the APG device.

[0021] Fig. 10B The embodiment of the present invention is shown Figure 5C Figure 4. Relationship between virtual / effective common-mode shift and leakiness of the APG device.

[0022] Fig.11 A schematic diagram of an APG device according to an embodiment of the present invention is shown.

[0023] Fig.12 The common mode motion and differential mode motion of the APG device according to the embodiment of the present invention in one cycle are shown.

[0024] Fig.13A The relationship between the synthetic common-mode displacement and common-mode acceleration of the APG device according to the embodiment of the present invention and the leakage degree is shown.

[0025] Fig. 13B and Fig. 13C The relationship between the synthetic common mode displacement and the leakage degree of the APG device according to the embodiment of the present invention is shown.

[0026] Fig.14 A schematic diagram of an APG device according to an embodiment of the present invention is shown.

[0027] Fig.15 A schematic diagram of an APG device according to an embodiment of the present invention is shown.

[0028] The reference numerals are as follows:

[0029] 10: Membrane structure

[0030] 100,200,300: Gas pulse generating device

[0031] 101,103: Petals

[0032] 101A,103A:Actuator

[0033] 102: Petal pair

[0034] 110: Support structure

[0035] 112,212,312,412,512: Gap

[0036] 1 / Z VV :Voice Guide

[0037] 220,240: protrusion

[0038] 222,242: concave part

[0039] 231,232: Line segment

[0040] 313:Exit

[0041] 315: Compression chamber

[0042] 320: Lid

[0043] 401,501: bottom

[0044] 402,502:Top

[0045] AA',BB',DD': hatch line

[0046] d 2 UV Z.COM / dt2 :Virtual acceleration

[0047] d AA : Anchor point to anchor point distance

[0048] D T :Tooth depth

[0049] H slit :high

[0050] P A ,P B :Air pressure

[0051] S IN :Input signal

[0052] SM: Modulation signal

[0053] t0~t6,(n)t CYC ~(n+1)t CYC : Time

[0054] T CY : Operation cycle

[0055] t CYC :Cycle time

[0056] W T :width

[0057] UV Z.COM :Virtual Sports

[0058] U Z.COM : Synthetic Common Mode Displacement

[0059] U Z_open : Displacement difference

[0060] X, Y, Z: coordinate axes

[0061] x 101L ,x 101R ,x 103L ,x 103R :Location

[0062] +SV,-SV: demodulated signal DETAILED DESCRIPTION

[0063] The disclosures of US Pat. No. 11,943,585 B2 and application No. 18 / 624,105 are incorporated herein by reference in their entirety and become a part of this specification.

[0064] The gas pulse generating device of the present application generally includes a pair of petals facing each other, which are made by etching a film layer, and the film layer is made of, for example, silicon-on-insulator (SOI) or polycrystalline silicon-on-insulator (POI) or other suitable materials. By adding a layer of piezoelectric material (such as PZT) deposited above the pair of petals, the pair of petals facing each other are actuated to move up and down to generate common mode motion and differential mode motion, thereby performing modulation and demodulation functions respectively.

[0065] Specifically, Figure 1 1 is a schematic cross-sectional view of an air-pulse generating (APG) device 100. The APG device includes a membrane structure (e.g., a diaphragm or a membrane) 10. The membrane structure 10 includes flaps 101 and 103 that are opposite to 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 form a flap pair 102. The flaps 101 and 103 are actuated to perform common mode motion to form an amplitude-modulated ultrasonic air pressure variation with an ultrasonic frequency (e.g., 192KHz), which can be regarded as a modulation operation. At the same time, the flaps 101 and 103 are also actuated to perform differential mode motion to form an opening 112 or a virtual valve (VV) 112 at an ultrasonic opening rate (eg, 192 KHz) for a demodulation operation.

[0066] In the embodiment shown in the APG device 100, differential mode motion (demodulation) and common mode motion (modulation) are performed simultaneously by the petal pair 102. In situ and concurrent modulation and demodulation can be achieved by a specific wiring scheme. For example, Figure 2 As shown, the APG device 100 may include an actuator 101A disposed on the petal 101 and an actuator 103A disposed on the petal 103. The actuators 101A and 103A include a top electrode and a bottom electrode. In one embodiment, the bottom electrodes of the actuators 101A and 103A receive a common mode modulation signal SM, and the top electrodes of the actuators 101A and 103A receive differential mode demodulation signals +SV and -SV. The demodulation signals +SV and -SV have opposite polarities. Please note that Figure 2As long as one electrode of the actuator 101A or 103A receives the modulation signal SM and the other electrode receives the demodulation signal SV (SV represents +SV or -SV), the requirements of the present invention are met and within the scope of the present invention.

[0067] The waveforms of the modulation signal SM and the demodulation signal ±SV can be referred to Figure 3 (or similar to Figure 3 ). Please note that the demodulation frequency of the demodulation signal SV is half of the modulation frequency of the modulation signal SM. For example, when the modulation frequency of the modulation signal SM is 192 KHz, the demodulation frequency of the demodulation signal SV is 96 KHz. Therefore, the flaps 101 and 103 form the opening 112 at an opening frequency of 192 KHz, and the APG device 100 operates at an ultrasonic pulse rate of 192 KHz. Pulse Generate multiple air pulses.

[0068] In the present application, "the flaps 101 and 103 perform 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 "the flaps 101 and 103 perform 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 driven by a pair of differential signals.

[0069] A gap 112 is formed between the flaps 101 and 103. In the present application, "gap", "opening" and "virtual valve" share the same reference numeral (e.g., 112) because they are located at the same position and express similar concepts from different levels. The flaps 101 and 103 are driven by the demodulated signals ±SV, and the distance between the free end of the flap 101 and the free end of the flap 103 is expanded, and the opening 112 or VV 112 is formed. Figure 1 The upper part shows the moment when VV 112 is closed or sealed. Figure 1 The lower half shows the moment when VV112 is turned on.

[0070] The pattern of the slits 112 on or above the membrane structure 10 is not limited. Intuitively, the slits 112 may have a straight-line slit pattern. FIG. 4A to FIG. 4C Schematic diagram of an APG device with a straight slit pattern is shown. Figure 4BAs shown, the slots 112 with a straight slot pattern can be considered to be projected or projected to the X direction or X dimension including zero projection. The APG device with a straight slot pattern is successful in generating asymmetric airflow pulses. However, the asymmetry of the air pressure pulses generated by the APG device with a straight slot pattern is not obvious and may not even be measured. This is because there is severe airflow congestion around the VV 112 and the airflow detours before reaching the VV 112 (such as Figure 4C shown). Figure 4C The air flow vectors around the VV 112 are schematically shown. Some of the drawings in the present application show the flaps 101 and 103 using different types of mesh bases, but this does not mean that the flaps 101 and 103 are made of different materials.

[0071] When VV 112 is (just) opened, airflow congestion increases the pressure difference ΔP around VV 112, where ΔP=P A -P B , P A represents the air pressure directly above the plane defined by the flap 101 or 103, P B represents the air pressure directly below the plane defined by flap 101 or 103. Ideally, when the VV opens, the pressure difference ΔP should be neutralized as quickly or as fast as possible. However, the neutralization of the pressure difference ΔP corresponding to the slot with a straight pattern is not fast enough. This is because of the lateral components of the airflow and the bypass of the airflow.

[0072] As shown in Figure 4, the airflow vector contains a strong lateral component, which means that the airflow is circumventing. (The lateral component refers to the component other than the Z direction; in Figure 4B The lateral component represents the component parallel to the X direction. The detour of the airflow not only lengthens the airflow path, but also slows down the reaction of the pressure balance on both sides of the flap 101 and the flap 103. When the gas reaches the vicinity of VV 112, the gas will queue up and wait in order to be squeezed through the narrow opening of VV 112. All of these steps or factors will lead to their own low pass filter (LPF) effects. Combining these factors, a powerful high-order LPF can be created, which can filter out f Pulse Since the highly asymmetric waveform means that there are significant spectral components in the higher harmonics, this f Pulse The harmonics of the amplifier weaken the asymmetry and reduce its effectiveness.

[0073] The asymmetry of the air pressure pulse is critical to the performance of the APG device, whether the APG device is used for sound generation applications (which can be considered as alternating current (AC) air flow) or for air movement applications (which can be considered as direct current (DC) air flow). A new APG design with air pressure pulse asymmetry is needed.

[0074] Here are a few guidelines. To avoid airflow congestion, VV should be designed to span a considerable amount in the X direction / dimension (or at least include a non-zero projection into the X direction / dimension). In other words, VV should span a significant percentage of the total area of ​​the flaps 101, 103 (or VV should occupy a significant area of ​​the flaps 101, 103). For example, VV 112 may span or occupy 20-40% (or at least 15%) of the total area of ​​the flaps 101, 103, but is not limited thereto.

[0075] Furthermore, to minimize the lateral component when the VV is "open", the acoustic impedance of the VV should be distributed in a mostly uniform manner in the X direction so that the air flows directly through the VV (mainly through the Z direction). Z.COM The amplitude of (x) is preferably distributed as nearly uniformly as possible in the X direction. Z.COM (x) is the combination or aggregation of the common mode shifts of flaps 101 and 103. Z.COM (x) can be expressed as 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) or ΔU z,103 (x) represents the common mode displacement of each flap 101 or 103 (corresponding to the X-dimensional variable x), w 101 (x) or w 103 (x) represents the corresponding weight factor. In one embodiment, w 101 (x) = w 103 (x)=0.5, but not limited to this.

[0076] In order to avoid airflow congestion and minimize the lateral component, one solution is to pattern or form slits in a zigzagging pattern on the membrane structure. In the present application, a slit with a zigzagging pattern may mean: 1) the slit is not straight; 2) the slit changes or changes its direction back and forth; or 3) since the slit is patterned to zigzag in a back-and-forth manner in the X direction and extends in the Y direction, the slit has a non-zero projection in the X direction / dimension when viewed from a top view. The projection of the zigzagging patterned slit projected into the X direction / dimension may have a length or depth that accounts for a significant proportion (e.g., greater than 15%) of the anchor-to-anchor distance of the APG device or flaps 101 and 103.

[0077] Please refer to FIG. 5A to FIG. 5D , which shows an APG device 200 according to an embodiment of the present invention. Figure 5C The back-and-forth bending pattern (part of it) of the slit 212 is shown from a top view. Figure 5A and Figure 5B Cross-sectional views along the sections AA' and BB' are shown when the flaps 101 and 103 remain flat (or when the VV 212 is closed). Figure 5D Schematically showing that when the VV212 with a back-and-forth bending pattern is opened, Figure 5C The airflow vector of the section line D-D'.

[0078] The width (eg, the size or dimension in the Y direction) of the APG device 200 is not limited to Figure 5C The APG device 200 may include a wide cantilever, which means that the width of the APG device 200 may be several times greater than the length (e.g., the dimension or size in the X direction) of the APG device 200. Alternatively, in one embodiment, the petals 101 and 103 may extend in the Y direction and have a relatively extreme aspect ratio (e.g., greater than 2 or less than 1 / 2), but is not limited thereto.

[0079] The gap 212 may have a tooth edge pattern. Specifically, Figure 6 The petals 101 and 103 are shown to be relatively far apart and have toothed patterned edges. Figure 6As shown, the flaps 101 / 103 include raised portions (protrusions) 220 / 240 and recessed portions (depressions) 222 / 242. The protrusions 220 and depressions 240 are staggered with each other. When the flaps 101 and 103 are separated only by the gap 212 (see Figure 5C and Figure 6 ), the protrusion 220 of the flap 101 is accommodated in the recessed portion 242 of the flap 103, and vice versa, so that the protrusion 220 of the flap 101 and the protrusion 240 of the flap 103 are staggered with each other. Figure 5C , the gap 212 has a rectangular tooth edge pattern.

[0080] from Figure 5C From the perspective of the present invention, the slit 212 is not a straight line, but changes or transforms its direction in a back-and-forth manner. The slit 212 can be regarded as a straight line in the x direction. 103L With x 101R Bend back and forth and extend in the Y direction. Tooth depth D T (i.e. x 103L With x 101R The distance between Figure 5C (shown) can be x 101L With x 103R The distance d between anchor points AA A certain proportion (eg, greater than 15% or 20-40%) of the APG device 200, wherein the flaps 101 and 103 of the APG device 200 should be anchored to the anchor structure like the APG device 100, but for simplicity, the anchor structure is omitted in FIG. 5.

[0081] Furthermore, the recessed portion 222 of the flap 101 may have a width W T , width W T It also represents the length of the line segment 231. Alternatively, ignoring the gap width, the protrusion 240 of the flap 103 may have a width W T .exist Figure 5C , W T It can be regarded as the width of a protruding portion of the flap 103. In order to effectively reduce the acoustic resistance, in one embodiment, the width W T It can be appropriately selected so that W T ≥1.5×H slit or W T ≥1.5×U Z_open (but not limited to this). Among them, H slit represents the height of the facing wall between the flaps 101 and 103, which is usually defined by the thickness of the membrane structure. Z_openrepresents the displacement difference in the Z direction between the free ends of flaps 101 and 103 when VV 212 is open. T ≥H slit or W T ≥U Z_open That is, it meets the requirements of the present invention and is within the scope of the present invention.

[0082] Since it has length W T , the protrusion of flap 103 will have a flat top (also indicated as 231), and the recessed portion of flap 101 will have a flat bottom (also indicated as 231). Note that the flat top of the protrusion of flap 101 or 103 helps to reduce acoustic resistance (compared to a protrusion with a sharp tip), and the flat bottom of flap 101 or 103 helps to enhance the effect of reducing inter-tooth acoustic resistance by increasing the length of the gap. In general, to reduce acoustic resistance, the gap can be patterned so that the protrusion of flap 101 or 103 has a flat portion (plateau) (e.g., 231) compared to a gap with a sawtooth or sinusoidal pattern.

[0083] Please note, Figure 5C The projection of the gap 212 to the X direction / dimension includes a non-zero projection (i.e., line segment 232). In contrast, geometrically or from a top-down perspective, Figure 4B The gap 112 is considered to have a zero projection in the X direction / dimension. In addition, compared to the gap 112, the gap 212 is elongated.

[0084] When the flaps 101 and 103 are actuated for differential mode motion, the acoustic resistance and lateral airflow component are significantly reduced because the slot 212 is lengthened and the slot 212 projection into the x direction / dimension includes a non-zero projection. 103L With x 101R In addition, if Figure 5D As shown, the airflow direction may be mostly perpendicular to the XY plane (ie, the plane defined by flaps 101 and 103 ). Therefore, the pressure difference ΔP (when VV 212 is open) may be neutralized more quickly than when VV 112 is open.

[0085] Figure 7 and Figure 8 The time series of common mode displacement and differential mode displacement are shown respectively, where t CYC represents the cycle time. In one embodiment, t CYC =1 / f PulseThese two time series are only used for illustration, as they may not exist separately in actual operation (e.g., in time-divisional operation), and through Figure 2 The wiring connection scheme shown will be combined into one movement of flap 101 and another movement of flap 103. For details, please refer to US Patent No. 11,943,585 B2 and its references, which are incorporated herein by reference in their entirety and become part of this specification.

[0086] like Figure 8 As shown, at (n+1 / 8)·t CYC to (n+3 / 8)·t CYC t , VV 212 is considered to be in the "open" state, and the area outlined by line segment 231 to 232 is considered to be "highly leaky", "acoustically transparent" and "non-pressurizing", which means that at (n+1 / 8)·t CYC to (n+3 / 8)·t CYC At the time between ΔP and ΔP, the common mode motion of the flaps 101 and 103 results in a minimum ΔP, and the common mode motion of the flaps 101 and 103 is effectively “cancelled”.

[0087] On the contrary, at (n+5 / 8)·t CYC to (n+7 / 8)·t CYC t , VV 212 is considered to be in the "closed" state, and the area outlined by line segment 231 to 232 is considered to be "non-porous", "acoustically opaque" and "pressurized", which means that at (n+5 / 8)·t CYC to (n+7 / 8)·t CYC In the time between the two, the petals 101 and 103 can be regarded as a continuous diaphragm, and in terms of diaphragm movement and diaphragm acceleration, the petals 101 and 103 behave like a complete diaphragm.

[0088] It can be seen that when the displacement difference between the petal 101 and the petal 103 is less than or equal to the thickness of the membrane structure (ie, ΔU Z ≤H slit ), VV (such as 112 or 212) is in the off state. Z =|U Z,101 -U Z,103 |,U Z,101 represents the vertical displacement of the flap 101 (eg, displacement in the Z direction / dimension), U Z,103represents the vertical displacement of the flap 103 (e.g., displacement in the Z direction / dimension). Please note that in the APG device of the present application, the closed state of VV occurs at the transitions of the differential mode motion of the flaps 101 and 103. In other words, when the flap 101 moves in a first direction (e.g., downward motion), and the flap 103 moves in a second direction opposite to the first direction (e.g., upward motion), the displacement difference (ΔU) between the free end of the flap 101 and the free end of the flap 103 is Z ) is less than the thickness H of the membrane structure slit In short, when the virtual valve is closed, both flaps are moving.

[0089] Fig. 9A and Fig. 9B The common mode and differential mode motion of the APG device 200 are respectively reproduced. Fig. 9A shows the resultant common mode displacement U corresponding to x when the two petals are actuated in common mode Z.COM (x), where x is the variable in the X dimension. Fig. 9B The acoustic conductance 1 / Z corresponding to x is shown when the two petals are actuated in differential mode. VV , where Z VV Represents the acoustic impedance or acoustic resistance of VV.

[0090] Depend on Fig. 9A It can be seen that compared with the synthetic common mode displacement U corresponding to VV 112 Z.COM (x), the synthetic common mode displacement U corresponding to VV 212 Z.COM (x) is evenly distributed in the x dimension. 103L With x 101R Between. Fig. 9B It can be seen that the acoustic impedance Z VV In x 103L With x 101R The range between is low and at x 103L With x 101R The gaps are roughly evenly distributed in the X dimension. In summary, the APG device with a back-and-forth curved gap (such as gap 212) is successful in avoiding airflow congestion and minimizing the lateral component, thereby resulting in an asymmetric air pressure pulse.

[0091] In addition, if Fig. 10A As shown, the “made vanish” period or VV open period (e.g. Figure 8 (n+1 / 8)·t CYC to (n+3 / 8)·t CYC) should be consistent with the effective displacement U Z.COM (t) Properly synchronized and aligned. Fig. 10B As shown, considering the "eliminated" period, the entity displacement U Z.COM (t) Can be converted to or considered as virtual / valid motion UV Z.COM For sound generation applications or air pressure pulse speaker (APPS) applications, this asymmetric virtual motion UV Z.COM Can be used to generate asymmetric pressure pulses (e.g. by chamber compression).

[0092] For example, see Fig.11 , which shows a schematic diagram of an APG device 300. The APG device 300 includes a VV 312 and a cover 320. The VV 312 can be a back-and-forth bending gap (such as VV 212). The cover 320 is used to form a compression chamber 315. Fig. 10A The timing diagram of Fig. 10B Asymmetrical "virtual / effective motion" UVs (shown) Z.COM Each segment of (t) can be compressed by the chamber, generating pressure pulses, which result in pressure variations at the outlet 313. These pressure variations cause sound waves (at the speed of sound) to propagate outward to the surrounding environment, forming a series of sound pressure pulses.

[0093] Note that when VV 312 is in the "closed" state, a pressure pulse is formed in chamber 315. Also, when VV 312 is in the "closed" state, the size of the pressure pulse is determined by the common mode displacement of flaps 101, 103. Conversely, during the "open" state of VV 312 / 212, the airflow through the flaps 101, 103 plates will produce a relatively small ΔP because of the extensive and evenly distributed airflow (over VV 312 / 212), minimal airflow congestion, low acoustic resistance across VV 312 / 212, and the straight and short airflow path; therefore, its impact on the net air pressure pulse generated by device 300 is minimal.

[0094] See also Fig.12 , which shows another schematic diagram of this common-mode and differential-mode interaction, applicable to the (indirect) pressure pulse generation method using a compression chamber. The differential mode motion is caused by Fig. 10A The "porosity" value shown is expressed as follows. Figure 8 (n+1 / 8)·t CYC to (n+3 / 8)·t CYCDuring the time between (n+1 / 8)·t and (n+1 / 8)·t, VV 212 enters a "highly leaky" state, and most of the ΔP generated by the common mode motion "leaks" through this leaky surface, resulting in CYC to (n+3 / 8)·t CYC The ΔP between the time and the time is zero or close to zero. Fig. 10B As shown, the ΔP generated by chamber compression is mainly caused by the occurrence of (n+5 / 8)·t CYC to (n+7 / 8)·t CYC The "virtual / effective displacement" of time between them dominates.

[0095] Several design metrics (relative to the effectiveness of avoiding airflow congestion) can be defined. For gap patterning, the area coverage ratio (ACR) and displacement coverage ratio (DCR) can be defined as:

[0096]

[0097] A(VV) in (Formula 1) refers to the area occupied by the gap (e.g., the back-and-forth bending gap 212), and A(101+103) refers to the total area of ​​the petals 101 and 103. Assuming that the periphery of the membrane structure is a rectangle, ACR can be further expressed as:

[0098]

[0099] In this application, especially in (Formula 2) and (Formula 3), x 101L or x 103L refers to the leftmost position of the petal 101 or 103 on the X-axis, x 101R or x 103R It refers to the rightmost position of the petal 101 or 103 on the X-axis. From another perspective, assuming that the periphery of the membrane structure is a rectangle, then x 101L or x 103R refers to the position where the petal 101 or 103 is anchored on the X-axis, x 101R or x 103L It is the rightmost or leftmost position of the protruding portion of the flap 101 or 103 on the X-axis.

[0100] In order to effectively avoid airflow congestion, it is recommended that ACR ≥ 0.25 and DCR ≥ 0.5, but not limited thereto.

[0101] The above-mentioned pressure pulse generation method is called the indirect method, which uses U Z.COM (t) or UV Z.COM The "displacement" of (t) compresses a small chamber (e.g., 315), generates a pressure pulse, and radiates this pressure pulse through a narrow orifice (e.g., 313).

[0102] In addition, a direct method can also be used to generate gas pressure pulses. The direct method conceptually uses VV (such as 112 or 212) to "eliminate" each pulse cycle t CYC The acceleration of the flaps 101 and 103 is expressed as d 2 U Z.COM (t) / dt 2 ), thereby generating a highly asymmetric “virtual acceleration” of the flaps 101 and 103 (the virtual acceleration can be expressed as d 2 UV Z.COM (t) / dt 2 ).

[0103] In the direct pulse generation method, the response is an asymmetric "virtual acceleration" d 2 UV Z.COM (t) / dt 2 Each section of the pressure pulse is generated. Fig.13A As shown, a pressure pulse is generated in response to U Z.COM (t) is a negative half-cycle common mode displacement, which is reflected by the positive value of d 2 UV Z.COM (t) / dt 2 A positive half-cycle acoustic output is produced. In contrast to the indirect method of generating air pressure pulses through chamber compression, in this case the air pressure pulses are generated directly because pressure is related to acceleration, which is the second derivative of displacement.

[0104] Fig.13A The timing alignment shown is U Z.COM (t) Center-to-center alignment between the open and closed states of VV (e.g., 112 or 212), but not limited thereto. For example, Fig. 13B Shows the Open-Close state timing ratio Z.COM (t) If the timing is advanced, Fig. 13C Shows the opening and closing state time point ratio U Z.COM (t) The case of time lag. Z.COM The optimal timing alignment between (t) and the on and off states of VV (eg, 112 or 212) depends on the duty cycle of VV or how long VV remains in the "off" state. All variations of these operating conditions are within the scope of the present invention.

[0105] The back-and-forth bending gap is not limited to a rectangular tooth edge pattern. The back-and-forth bending gap may be a trapezoidal tooth edge pattern. For example, in Fig.14 and Fig.15 , the gaps 412 and 512 have a trapezoidal tooth edge pattern. Fig.14 The bottom (eg 401 ) of the protrusion of the flap 101 is wider than the top (eg 402 ); and Fig.15 The top (e.g., 502) of the protrusion of the flap 101 is wider than the bottom (e.g., 501). Both cases and their variations (e.g., rounded or chamfered corners of the protrusion of the rectangular or trapezoidal slit) are within the scope of the present invention.

[0106] Please note that the APG device of the present invention can be applied to sound generation applications and used as an air pressure pulse speaker (APPS), wherein the generated multiple air pulses are amplitude modulated and the envelopes of these air pulses (or the input signal S IN ) is or contains an alternating current (AC) component, which may, for example, result in an AC airflow. (See Figure 3 The modulation signal SM is based on the input signal S IN Generated. ) Input signal S IN It may be or include an audio signal. The APG or APPS of the present invention may be set in or applied to a wearable audio device, such as an earbud, a communication headset, a True Wireless Stereo (TWS), a headphone, or a hearing aid. The APG or APPS of the present invention may also be used as a loudspeaker or an open field speaker, which may be set in an open wearable stereo (OWS), a mobile phone (as a receiver or speaker), a tablet computer, a laptop computer, a desktop (game or video) display, a television, an augmented reality (AR) device, or a virtual reality (VR) device, but is not limited thereto.

[0107] In addition, the APG device of the present invention can also be applied to air movement applications, which has functions similar to fans, blowers, etc., wherein the envelopes of the generated multiple air pulses (or the input signal S IN ) is or contains a direct current (DC) component, which may, for example, result in a DC airflow. (The modulation signal SM is based on the input signal S IN Generated. ) Input signal S INIt may be or include a DC signal. The APG device of the present invention may be used for heat dissipation, ventilation, cooling, drying or air quality sensing in air movement applications, but is not limited thereto. The details of the APG device in air movement applications have been described in U.S. Patent Application No. 18 / 624,105, and for the sake of brevity, will not be repeated here.

[0108] In short, the present invention utilizes a back-and-forth bending gap or a gap with a toothed edge to enhance the asymmetry of the gas pulse, thereby improving the performance of the APG device.

[0109] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the claims of the present invention should fall within the scope of the present invention.

Claims

1. A gas pulse generating device, comprising: A membrane structure, comprising a first flap and a second flap opposite to each other; wherein the membrane structure is actuated to operate at an ultrasonic frequency, and the gas pulse generating device generates a plurality of gas pulses at an ultrasonic pulse rate; wherein the first flap and the second flap are actuated to perform a differential mode motion to form an opening or a virtual valve; Wherein, a gap is formed between the first flap and the second flap, and the opening or the virtual valve is formed by the gap; The gap forms a back-and-forth bending pattern on the membrane structure.

2. The gas pulse generating device according to claim 1, in, The slot bends back and forth in a first direction and extends toward a second direction.

3. The gas pulse generating device according to claim 2, in, The gap has a non-zero projection when projected toward the first direction.

4. The gas pulse generating device according to claim 1, in, The first flap includes a plurality of first protrusions, and the second flap includes a plurality of second protrusions; The plurality of first protrusions and the plurality of second protrusions are interlaced with each other.

5. The gas pulse generating device according to claim 4, in, The first flap includes a plurality of first recessed portions, and the second flap includes a plurality of second recessed portions; The plurality of first protrusions and the plurality of first recesses are interlaced with each other.

6. The gas pulse generating device according to claim 1, in, The first flap includes a plurality of first protrusions; Wherein, one of the plurality of first protrusions includes a flat portion.

7. The gas pulse generating device according to claim 1, in, The first flap includes a plurality of first protrusions; wherein one of the plurality of first protrusions corresponds to a width; The width is greater than the height of the wall between the first flap and the second flap.

8. The gas pulse generating device according to claim 1, in, The first flap includes a plurality of first protrusions; wherein one of the plurality of first protrusions corresponds to a width; The width is greater than a displacement difference between a free end of the first flap and a free end of the second flap when the virtual valve is opened.

9. The gas pulse generating device according to claim 1, in, The first flap includes a plurality of first protrusions; wherein one of the plurality of first protrusions corresponds to a depth; The depth is greater than 15% of the distance between anchor points.

10. The gas pulse generating device according to claim 1, wherein: The gap forms a toothed edge pattern.

11. The gas pulse generating device according to claim 1, wherein: The gap forms a rectangular toothed edge pattern.

12. The gas pulse generating device according to claim 1, wherein: The gap forms a trapezoidal tooth edge pattern.

13. The gas pulse generating device according to claim 1, in, The membrane structure is actuated to perform a common mode motion to produce amplitude modulated ultrasonic air pressure variations having an ultrasonic frequency.

14. The gas pulse generating device according to claim 13, in, The first flap and the second flap are actuated to perform the common mode motion and the differential mode motion simultaneously.

15. The gas pulse generating device according to claim 1, in, The first flap and the second flap are actuated to perform the differential mode motion to form the opening at an ultrasonic opening frequency.

16. The gas pulse generating device according to claim 1, in, When the difference between the displacement of the first flap and the displacement of the second flap is smaller than the thickness of the membrane structure, the virtual valve is in a closed state; The closed state of the virtual valve occurs in a transition state of the differential mode motion of the first flap and the second flap.

17. The gas pulse generating device according to claim 1, in, The slit bends back and forth on the membrane structure so that an area coverage ratio is not less than 0.

25.

18. The gas pulse generating device according to claim 1, in, The slit bends back and forth on the membrane structure so that a displacement coverage ratio is not less than 0.

5.

19. The gas pulse generating device according to claim 1, in, The first petal and the second petal form a petal pair; wherein a time point at which the virtual valve is closed is aligned with a time point corresponding to a common mode movement of the flap pair in a first direction; The time point at which the virtual valve is opened is aligned with the time point corresponding to the common mode movement of the flap pair in a second direction, and the second direction is opposite to the first direction.

20. The gas pulse generating device according to claim 1, comprising: a cover structure; A chamber is formed between the membrane structure and the cover structure.

21. The gas pulse generating device according to claim 20, in, An opening is formed on the cover structure; The plurality of gas pulses propagate outward through the orifice.

22. The gas pulse generating device according to claim 1, in, The first petal and the second petal form a petal pair; The time point at which the virtual valve is closed is aligned with the time point corresponding to the peak acceleration of a common-mode motion of the flap pair.

23. The gas pulse generating device according to claim 1, in, A synthetic common mode displacement corresponding to the virtual valve is evenly distributed in a range between a rightmost free end of the first flap and a leftmost free end of the second flap.

24. The gas pulse generating device according to claim 1, in, The acoustic resistance corresponding to the virtual valve is evenly distributed in a range between a rightmost free end of the first flap and a leftmost free end of the second flap.

25. The gas pulse generating device according to claim 1, wherein: The air pulse generating device is used for sound generation applications.

26. The gas pulse generating device according to claim 1, wherein: The air pulse generator is used for air movement applications.

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