2, since the vent opening OPV is temporarily closed and has the larger flowing resistance, the air pressures on two opposite sides of the film structure 10 are different to cause an air-pressure difference. Namely, the film structure 10 (the flap pair) performs the common mode movement S2 to form an air pressure variation.

In FIG. 2, the film structure 10 (the flap pair) may be actuated to perform a differential mode movement S3, such that the flap 101 and the flap 103 are simultaneously actuated to move toward opposite directions. For example, the flap 101 may be actuated to move downwards and the flap 103 may be actuated to move upwards (as shown in FIG. 2), or the flap 101 may be actuated to move upwards and the flap 103 may be actuated to move downwards. For example, in the end of the differential mode movement S3, a distance between the flap 101 and the first position and a distance between the flap 103 and the first position are the same.

As shown in FIG. 2, when the film structure 10 (the flap pair) is actuated to perform the differential mode movement S3, the vent opening OPV may be temporarily opened, such that the air may easily flow to pass through a space between two opposite sidewalls of the slit SL. In FIG. 2, two opposite sidewalls of the slit SL (i.e., the first free edge 101n1 of the flap 101 and the second free edge 103n1 of the flap 103) do not overlap with each other in the horizontal direction, so as to make the vent opening OPV opened and have the lower flowing resistance.

When the film structure 10 (the flap pair) is actuated to perform the differential mode movement S3, if the air-pressure difference exists between two opposite sides of the film structure 10, the air naturally flows to pass through the vent opening OPV due to this air-pressure difference and the lower flowing resistance of the vent opening OPV, such that the airflow and/or the air pulse can be generated.

Accordingly, the airflow producing method of this embodiment may generate the airflow and/or the air pulse by actuating the film structure 10 (the flap pair) to perform the common mode movement S2 and the differential mode movement S3. For instance, one period of the airflow producing method of this embodiment may include four steps, but not limited thereto. The first step of the airflow producing method may be that the film structure 10 (the flap pair) is actuated to perform the common mode movement S2 to make the air-pressure difference exist between two opposite sides of the film structure 10. The second step of the airflow producing method may be that the film structure 10 (the flap pair) is actuated to recover the intermediate status S1. The third step of the airflow producing method may be that the film structure 10 (the flap pair) is actuated to perform the differential mode movement S3 to make air naturally flows to pass through the vent opening OPV due to this air-pressure difference and the lower flowing resistance of the vent opening OPV, such that the airflow and/or the air pulse can be generated. The fourth step of the airflow producing method may be that the film structure 10 (the flap pair) is actuated to recover the intermediate status S1. By repeating the periods of the airflow producing method of this embodiment, the air pulses may form the airflow continuously.

A frequency of the period may be designed based on the pulse rate of the air pulse, wherein the frequency of the period may be synchronous with the pulse rate of the air pulse. In the present invention, a frequency/rate is synchronous with another frequency/rate generally refers that this frequency/rate is this another frequency/rate times a rational number (i.e., N/M, wherein N and M represent integers). In some embodiments, the frequency of the period may be the same as the pulse rate of the air pulse. In some embodiments, the film structure 10 (the flap pair) performs the common mode movement S2 to form the air pressure variation with a pressure variant frequency synchronous with the frequency of the period, and the film structure 10 (the flap pair) performs the differential mode movement S3 to form the vent opening OPV at an opening rate synchronous with the pressure variant frequency and the frequency of the period. For instance, the frequency of the period, the pulse rate of the air pulse, the pressure variant frequency and the opening rate are the same. For instance, if the air pump AFC produces the air pulses at an ultrasonic rate, the pressure variant frequency and the opening rate are synchronous with this ultrasonic rate.

Flowing directions of the airflow and the air pulse are determined by a direction of the common mode movement S2 performed by the film structure 10 (the flap pair). When the film structure 10 (the flap pair) is actuated to move upwards (or downwards) for only performing one type of common mode movement S2 in the first step of the several periods, the types of the air-pressure differences in the first step of these periods are the same, thereby making the flowing directions of the air pulses generated in these periods (the third step) be the same. Thus, the air pump AFC shall produce single-ended (SE) air pulses or SE-liker air pulses. Also, the air pulse may be asymmetric.

In the present invention, a waveform of the SE air pulse or a waveform of the SE-liker air pulse may refer that the waveform is (substantially) unipolar with respect to certain level. For instance, the SE air pulse or the SE-liker air pulse may refer to the waveform which is (substantially) unipolar with respect to ambient pressure (e.g., 1 ATM). Namely, the SE air pulses or the SE-liker air pulses constitute a net air movement or a net airflow toward one single direction.

The airflow producing method of the present invention is not limited by the above. In one period of the airflow producing method, the number of the steps and the order of the actuating movements of the film structure 10 (the flap pair) may be designed based on requirement(s).

In another aspect, for any common mode movements S2 of the flap pair, a pair of acoustic pressure waves will be produced, one in space on a side of the film structure 10, and one in space on an opposite side of the film structure 10. These two acoustic pressure waves will be of the same magnitude but of opposite polarities. As a result, when the vent opening OPV is opened, the air-pressure difference between the two air volumes in the vicinity of the vent opening OPV would neutralize each other. Therefore, when the timing of differential mode movement S3 reaching its peak (i.e., the timing which the vent opening OPV is maximum) is aligned to the timing of acceleration of common mode movement S2 reaching its peak, the acoustic pressure supposed to be generated by the common mode movement S2 shall be subdued/eliminated due to the opening of the vent opening OPV, causing the auto-neutralization between two acoustic pressures on the two opposite sides of the film structure 10, where the two acoustic pressures would have same magnitude but opposite polarities. It means, when the vent opening OPV is opened, the air pump AFC would produce (near) net-zero air pressure. Therefore, when the opened period of the vent opening OPV overlaps a time period of one of the (two) polarities of acceleration of common mode movement S2 of the flap pair, the air pump AFC shall produce SE air pulses or SE-liker air pulses.

Furthermore, by aligning the timing of opening of the vent opening OPV to the timing of acceleration of common mode movement S2 of the flap pair, the air pump AFC would be able to produce asymmetric air pulses.

In some embodiments, the film structure 10 (the flap pair) may be actuated to perform the common mode movement S2 and the differential mode movement S3 simultaneously, but not limited thereto. In some embodiments, the film structure 10 may include other part to make the common mode movement S2 and the differential mode movement S3 be performed by the film structure 10 simultaneously, but not limited thereto.

In the present invention, the actuator AT may receive any suitable signal to actuate the film structure 10. In some embodiments, the film structure 10 is actuated by a modulation-driving signal SM to perform the common mode movement S2 to form the air pressure variation, and the film structure 10 is actuated by a demodulation-driving signal SV to perform the differential mode movement S3 to form the vent opening OPV, wherein both the modulation-driving signal SM and the demodulation-driving signal SV are related to an output amplitude of the air pulse. Note that the demodulation-driving signal SV may be +SV or -SV shown in FIG. 4.

Furthermore, a modulation frequency of the modulation-driving signal SM and a demodulation frequency of the demodulation-driving signal SV are related to the pulse rate of the air pulse. For example, the modulation frequency and the demodulation frequency may be synchronous with the pulse rate of the air pulse, such that the modulation frequency and the demodulation frequency may be synchronous with the pressure variant frequency of the air pressure variation, the opening rate of the vent opening OPV and the frequency of the period, but not limited thereto.

In some embodiments, the actuator AT may receive the modulation-driving signal SM and the demodulation-driving signal SV at different times, but not limited thereto. In some embodiments, the actuator AT may include a plurality sub-parts in the top view, one sub-part may receive the modulation-driving signal SM, and another sub-part may receive the demodulation-driving signal SV, but not limited thereto. In some embodiments, the actuator AT may include a first electrode and a second electrode, the first electrode may receive the modulation-driving signal SM, and the second electrode may receive the demodulation-driving signal SV, but not limited thereto.

Furthermore, by controlling the modulation-driving signal SM and/or the demodulation-driving signal SV, the flowing direction of the airflow (the air pulse) produced by the air pump AFC may be reversible. Details of which may be referred to U.S. application Ser. No. 18/624,105, which are not narrated herein for brevity.

The details of the airflow generating MEMS device (which may be fabricated by semiconductor process), i.e., the air pump AFC (e.g., the structure, the driving signal and the movement) and their design/operational principles can be referred to U.S. Pat. No. 11,943,585, U.S. application Ser. Nos. 18/321,757 and 18/624,105 filed by same applicant. Thus, the contents of these US patents and US applications are incorporated herein by reference.

As mentioned earlier, the air pump AFC of the present application may be capable of producing asymmetric air pulses, and can be applied in cooling, drying, dehumidifying, heat dissipation, ventilation, air-sampling and/or air-pumping applications, where the (asymmetric) air pulses are produced to form a net air movement constantly in one direction.

Furthermore, the air pump AFC of the present invention for airflow applications may be disposed within an air quality sensing device, which is to sense, e.g., a density of specific particle(s) (e.g., PM 2.5 or PM 10 (PM: Particulate Matter)) or compound(s) (e.g., ozone (O₃), nitrogen dioxide (NO₂), sulfur dioxide (SO₂) and carbon monoxide (CO)) in the air. Hence, a size of the air quality sensing device may be significantly reduced.

For example, FIG. 3 illustrates a schematic diagram of air pulses AP according to an embodiment of the present invention. The air pulses may be generated by the air pump AFC of present application, which comprises a film structure 10. As mentioned earlier, the film structure 10 of the air pump AFC may be actuated to perform a movement to generate the air pulses AP at an ultrasonic rate f_pulse(e.g., 96 KHz or 192 KHz), which may be a reciprocal of the operating cycle T_CYof the ultrasonic carrier frequency f_UCfor example. In this case, the ultrasonic rate f_pulsemay be the ultrasonic carrier frequency f_UC. The air pulses AP may produce a net airflow toward a single direction.

In an embodiment, first air pulses AP1 may produce a first net airflow constantly toward one single direction, e.g., a first direction D1. Taking FIG. 3 as an example, during the first period of time T1, the air pulses AP are all toward first direction D1. When the first time period T1 is at least or longer than a reciprocal of a minimum audible frequency, the first net airflow produced by the first air pulses AP1 may be considered as constantly toward one single direction D1. For example, for a minimum audible frequency being acknowledged as 10 Hz, when the first time period T1 is at least or longer than 0.1 second, the first net airflow may be considered as constantly toward one single direction D1. Note that, first amplitude(s), corresponding to the first air pulses AP1 toward the first direction D1, may or may not be the same.

On the other hand, the air pump AFC may produce second air pulses AP2, and the second air pulses AP2 may produce a second net airflow constantly toward a second direction D2, opposite to the first direction D1. In an embodiment, when the air pump AFC produces significant airflow or air movement and the air pulses toggling between the first direction D1 and the second direction D2 is not discernible, the first net airflow may be considered as constantly toward direction D1 during period T1, and/or the second net airflow may be considered as constantly toward direction D2 during period T2.

The film structure may be actuated by a demodulating-driving signal (e.g., ±SV) and a modulating-driving signal (e.g., SM). Note that, in the present application, SM may be referred to modulation signal, which is also a kind of driving signal. Similarly, ±SV may be referred to demodulation signal, which is also a kind of driving signal.

FIG. 4 illustrates schematic waveforms of the demodulation signals (±SV) and the modulation signal (SM) according to another embodiment of the present invention, neglecting transition between high/low voltages thereof. As shown in FIG. 4, the modulation/driving signal (SM) may be generated according to an input signal (e.g., a input audio signal S_IN), which comprises or is a (nonzero) direct current (DC) offset (e.g., a (nonzero) DC voltage). In other words, the input signal may be simply a DC signal, but not limited thereto.

In an embodiment, the DC offset may be related to the direction of the net airflow. For example, during a first period of time T1, the air pulses (AP) may produce a first net airflow constantly toward the first direction D1 in response to the DC offset being positive. On the other hand, during a second period of time T2, the air pulses generated by the air pump AFC may produce the second net airflow constantly toward the second direction D2, which is opposite to the first direction D1, in response to the DC offset being negative. In this regard, the air pump AFC or airflow generating device of the present invention may be viewed as a voltage-to-airflow converter, which can convert voltage into airflow.

In addition to polarity of the DC offset, the direction of net airflow may also be determined/controlled via phase between the modulation signal (SM) and the demodulation signal (±SV). For example, in FIG. 4, transitions of the demodulation signal (±SV) are aligned to interval of the modulation signal (SM) being low. In this case, the air pump AFC may produce airflow toward a third direction for example. When (phase of) the demodulation signal (±SV) is shifted such that transitions of the demodulation signal (±SV) are aligned to interval of the modulation signal (SM) being high, the air pump AFC would produce airflow toward a fourth direction opposite to the third direction. In short, the direction of the net airflow produce by the air pump AFC may be determined/controlled via phase (difference) between the modulation signal (SM) and the demodulation signal (±SV).

The strength/volume of a net airflow may be related to or a function of the magnitude of the DC offset. By maintaining an airflow direction (either the first direction or the second direction), the air pump AFC is able to dissipate heat, dehumidify, provide ventilation, provide air-sampling application, provide air-pumping application and/or facilitate air circulation. In this case, the air pump AFC can be regarded as a bladeless fan. That is, the air pump AFC may also be regarded as bladeless fan, especially when the driving signal or modulation-driving signal applied thereto is generated according to an input signal comprising nonzero DC component/offset. In the present invention, the terms of air-pulse generating device, airflow generating device, air pump and blower may be used interchangeably.

Due to the small size of the air pump of the present invention, it is possible for an air quality sensing module comprising the air pump to be disposed within (integrated into) a handheld device. For example, the handheld device may be a (smart) phone, a (smart) watch or other suitable handheld portable device.

Referring to FIG. 5, FIG. 5 is a schematic diagram of an air pump or an airflow generating device according to an embodiment of the present invention. Note that the airflow generating device Q00 shown in FIG. 5 may be an example used in the air quality sensing module, and the airflow generating device Q00 may be a MEMS chip for example. As shown in FIG. 11, two flaps 101 and 103 of the airflow generating device Q00 are opposite to each other in a top view viewing along a top-view direction (i.e., the direction Z), and the actuators AT1 and AT2 are respectively disposed on the flaps 101 and 103. Note that the two flaps 101 and 103 form a flap pair.

In FIG. 5, the flap 101 includes a first anchored edge 101r anchored on the anchor structure AR, and the flap 101 includes first free edges 101n other than the first anchored edge 101r which are non-anchored. Similarly, the flap 103 includes a second anchored edge 103r anchored on the anchor structure AR, and the flap 101 includes second free edges 103n other than the second anchored edge 103r which are non-anchored. Namely, each of the flaps 101 and 103 only has one anchored edge, and other edges are free edges.

In FIG. 5, a slit SL is formed between the flaps 101 and 103, such that the flaps 101 and 103 are divided by the slit SL, and one first free edge 101n1 of the flap 101 and one second free edge 103n1 of the flap 103 are defined by the slit SL (the first free edge 101n1 and the second free edge 103n1 are opposite sidewalls of the slit SL). Note that the vent opening OPV formed between the flaps 101 and 103 is formed because of the slit SL.

In short, the airflow generating device Q00 comprises two flaps disposed opposite to each other, and each flap has one edge anchored and the rest edges non-anchored. Simulation and experiments results validate that the airflow generating device of the present invention (e.g., Q00) is able to produce significant airflow. In some experiments, the airflow generating device of the present invention (e.g., Q00) may have PQ (Pressure-Airflow) curve with maximum (static/back) pressure P_maxas 800˜1300 Pa and maximum airflow volume Q_maxas 25˜45 cc/sec, where Pa represents Pascal cc/sec represents cubic centimeters per second.

The airflow generating device of the present invention (e.g., Q00) may be disposed within various electronic devices. For example, the airflow generating device of the present invention may be disposed within a phone.

FIG. 6 is a schematic diagram of an appearance of a phone 20 according to an embodiment of the present invention. FIG. 7 is an internal layout diagram of the phone 20 according to an embodiment of the present invention. FIG. 8 is a (local) detailed view of the internal layout diagram of the phone 20 according to an embodiment of the present invention. FIG. 9 is a (local) cross-sectional view of the phone 20 according to an embodiment of the present invention.

The phone 20 comprises a back cover 23. An inlet 230 and an outlet 232 are formed on the back cover 23. A cold airflow (denoted as “cold AF” afterward) may flow into the phone 20 via the inlet 230 and a hot/warm airflow (denoted as “hot AF” afterward) may flow outward from the phone 20. The inlet 230 and the outlet 232 are connected to a flow channel (e.g., 26 shown later) formed within the phone 20.

The phone 20 comprises an airflow generating device 22 and a heat spreading component 21. The airflow generating device 22 may have the same or similar structure as the airflow generating device Q00. In an embodiment, the heat spreading component 21 may be or comprise a vapor chamber VC. The phone 20 may comprise (high performance) computing device as heat generating device. The (high performance) computing device as heat generating device may be attached to the vapor chamber VC such that the vapor chamber VC may dissipate heat generated by the computing device. The airflow generating device 20 may dissipate/remove heat from the vapor chamber VC or the heat spreading component 21.

The phone 20 may comprise a flow guide 24. The airflow generating device 20 may generate an airflow AF flowing through the flow guide