The present application relates to an air pulse generating element and a sound producing device, and more particularly, to an air pulse generating element and a sound producing device with low manufacturing complexity and low yield loss rate.

Speaker driver and back enclosure are two major design challenges in the speaker industry. It is difficult for a conventional speaker driver to cover an entire audio frequency band, e.g., from 20 Hz to 20 KHz, due to a membrane displacement D is proportional to 1/f², i.e., D ∝ 1/f². On the other hand, to produce sound with high fidelity, a volume/size of back enclosure for the conventional speaker is required to be sufficiently large.

To combat against the design challenges in the above, applicant has proposed an air pulse generating element and a sound producing device in U.S. Application No. 16/125,761, which produce sound using a plurality of pulses at a pulse rate, where the pulse rate is higher than a maximum audible frequency and the plurality of pulses is regarded as being amplitude modulated according to an input audio signal. By exploiting a low pass effect caused by ambient environment and human ear structure, a sound corresponding to the input audio signal is perceived. The sound producing device in U.S. Application No. 16/125,761 is able to cover the entire audio frequency band, and an enclosure volume/size of which is significantly reduced.

However, the air pulse generating element in U.S. Application No. 16/125,761 is complicated to be manufactured, because it requires 3 different layers to manufacture the valves and the membrane thereof, suffering from high yield loss rate. Specifically, FIG. 1 is a sectional view of an air pulse generating element 10 in U.S. Application No. 16/125,761. The air pulse generating element 10 comprises valves 101-104, a membrane 105, a front faceplate 106 and a back faceplate 107. The membrane 105 partitions a chamber 108 into a front sub-chamber 108_f and a back sub-chamber 108_b. The air pulse generating element 10 is a MEMS (micro electrical mechanical system) device. The valves 101 and 103 are fabricated at a layer 1, the membrane 105 is fabricated at a layer 3, and the valves 102 and 104 are fabricated at a layer 5. Manufacturing the valves 101-104 and the membrane 105 at the layers 1, 3, 5 require high wafer cost. In addition, one yield loss of one single layer among the layers 1, 3, 5 would lead to a failure of the entire air pulse generating element 10. Thus, the yield loss rate of the 3-layered air pulse generating element 10 is high.

Therefore, it is necessary to lower the manufacturing complexity of the air pulse generating element.

It is therefore a primary objective of the present application to provide an air pulse generating element and a sound producing device with low manufacturing complexity and low yield loss rate.

An embodiment of the present invention discloses an air pulse generating element disposed in a sound producing device. The air pulse generating element comprises a membrane, disposed within a chamber; and a plurality of valves, disposed by the membrane within the chamber, configured to seal a plurality of openings of the chamber in response to a plurality of valve control signals; wherein the membrane and the plurality of valves are all fabricated at a first layer.

An embodiment of the present invention discloses a sound producing device. The sound producing device comprises a plurality of air pulse generating elements, wherein an air pulse generating element comprises a membrane, disposed within a chamber; and a plurality of valves, disposed by the membrane within the chamber, configured to seal a plurality of openings of the chamber in response to a plurality of valve control signals; wherein the membrane and the plurality of valves are all fabricated at a first layer; and a control unit, configured to generate the plurality of valve control signals.

• FIG. 1 is a schematic diagram of an air pulse generating element in the art.
• FIG. 2 is a top view of an air pulse generating element according to an embodiment of the present invention.
• FIG. 3 is a first sectional view of the air pulse generating element of FIG. 2.
• FIG. 4 is a second sectional view of the air pulse generating element of FIG. 2.
• FIG. 5 is a timing diagram of valve control signals and a membrane driving voltage according to an embodiment of the present invention.
• FIG. 6 is a top view of an air pulse generating element according to an embodiment of the present invention.
• FIG. 7 is a first sectional view diagram of the air pulse generating element of FIG. 6.
• FIG. 8 is a schematic diagram of valve movement according to an embodiment of the present invention.
• FIG. 9 is a schematic diagram of a valve according to an embodiment of the present invention.
• FIG. 10 is a schematic diagram of a valve according to an embodiment of the present invention.
• FIG. 11 is a schematic diagram of a sound producing device according to an embodiment of the present invention.

FIG. 2 is a top view of an air pulse generating element 20 according to an embodiment of the present invention. FIG. 3 is a sectional view of the air pulse generating element 20 through an A-A' line shown in FIG. 2. FIG. 4 is a sectional view of the air pulse generating element 20 through a B-B' line shown in FIG. 2. The air pulse generating element 20 comprises valves 201-204, a membrane 205, a front faceplate 206 and a back faceplate 207. The valves 201-204 are disposed by four sides s1-s4 of the membrane 205, respectively, within a chamber 208. The membrane 205 partitions the chamber 208 into a front sub-chamber 208_f and a back sub-chamber 208_b. The valves 201-204 may be controlled by a plurality of valve control signals, respectively. The air pulse generating element 20 is a MEMS (micro electrical mechanical system) device. In an embodiment shown in FIGs. 2-4, the front faceplate 206 is disposed at a layer 1, the valves 201-204 and the membrane 205 are all fabricated at a layer 3, and the back faceplate 207 is disposed at a layer 5. Supporting elements 223, 224 are fabricated at a layer 2, and supporting elements 221, 222 are fabricated at a layer 4.

Openings 211 and 213 are formed within the front faceplate 206, and openings 212 and 214 are formed within the back faceplate 207. In an embodiment, the valve 201 is controlled in response to a valve control signal G to move upward to seal the openings 211, the valve 202 is controlled in response to a valve control signal H to move downward to seal the openings 212, the valve 203 is controlled in response to the valve control signal H to move upward to seal the openings 211, and the valve 204 is controlled in response to the valve control signal G to move downward to seal the openings 214.

In the embodiment stated in the above, the valve control signals G and H are configured to control the valves 201-204 to perform an open-and-close movement. When the valve control signal G controls the valves 201, 204 to be opened, denoted as "G=1", the opening 211, 214 are not sealed and air flows through the opening 211, 214. When the valve control signal G controls the valves 201, 204 to be closed, denoted as "G=0", the opening 211, 214 are sealed and air is not able to flow through the opening 211, 214. When the valve control signal H controls the valves 202, 203 to be opened, denoted as "H=1", the opening 212, 213 are not sealed and air flows through the opening 212, 213. When the valve control signal H controls the valves 202, 203 to be closed, denoted as "H=0", the opening 212, 213 are sealed and air is not able to flow through the opening 212, 213.

In addition, the membrane 205 is controlled in response to a membrane driving voltage V_MBN to either move upward (i.e., from back to front) or move downward (i.e., from front to back). In other words, the valve control signals G and H are configured to control the valves 201-204 to perform an open-and-close movement, and the membrane driving voltage V_MBN is configured to drive the membrane to perform an up-and-down movement. When the membrane 205 moves upward, an instantaneous front air pressure of the front sub-chamber 208_f is increased and an instantaneous back air pressure of back sub-chamber 208_b is decreased. When the membrane 205 moves downward, the instantaneous front air pressure of the front sub-chamber 208_f is decreased and the instantaneous back air pressure of the back sub-chamber 208_b is increased.

FIG. 5 is a timing diagram of the valve control signals G, H and the membrane driving voltage V_MBN according to an embodiment of the present invention. In FIG. 5, hexagons within the timing diagram of the valve control signals G, H represents that the corresponding valve(s) is opened, i.e., G=1 or H=1, and straight lines within the timing diagram of the valve control signals G, H represents that the corresponding valve(s) is closed, i.e., G=0 or H=0. The valve control signals G, H and the membrane driving voltage V_MBN are mutually synchronized.

A pulse cycle 114a begins at a status of G=1 and H=0. If the membrane driving voltage V_MBN drives the membrane 205 to move upward (i.e., from back to front) during the pulse cycle 114a, the air is pushed from the front sub-chamber 208_f to a front environment through the opening 211 and pulled from a back environment to the back sub-chamber 208_b through the opening 214, and therefore a positive air pulse (in a back-to-front direction) is generated. If the membrane driving voltage V_MBN drives the membrane 205 to move downward (i.e., from front to back) during the pulse cycle 114a, the air is pulled from the front environment to the front sub-chamber 208_f through the opening 211 and pushed from the back sub-chamber 208_b to the back environment through the opening 214, and therefore a negative air pulse (in a front-to-back direction) is generated.

In other words, during the pulse cycle 114a beginning at the status of G=1 and H=0, i.e., the valves 201, 204 being opened and the 202, 203 being closed, the membrane movement direction corresponding of the membrane 205 would be substantially the same as the air pulse direction.

A pulse cycle 114b begins at a status of G=0 and H=1. If the membrane driving voltage V_MBN drives the membrane 205 to move upward during the pulse cycle 114b, the air is pushed from the front sub-chamber 208_f to the back environment through the opening 212 and pulled from the front environment to the back sub-chamber 208_b through the opening 213, and therefore a negative air pulse is generated. If the membrane driving voltage V_MBN drives the membrane 205 to move downward during the pulse cycle 114b, the air is pulled from the back environment to the front sub-chamber 208_f through the opening 212 and pushed from the back sub-chamber 208_b to the front environment through the opening 213, and therefore a positive air pulse is generated.

In other words, during the pulse cycle 114b beginning at the status of G=0 and H=1, i.e., the valves 201, 204 being closed and the 202, 203 being opened, the membrane movement direction corresponding of the membrane 205 would be substantially opposite to the air pulse direction.

Operations of the air pulse generating element 20 are tabulated in Table I. Up-and-Down Movement of Membrane Status of Valves at Beginning of Pulse Cycle G=1, H=0 G=0, H=1 Downward Front-to-Back Back-to-Front Upward Back-to-Front Front-to-Back

In addition, during the pulse cycle 114a or 114b, if the membrane driving voltage V_MBN is constant and the membrane 205 remains static, moving neither upward nor downward, a null pulse is generated.

Note that, an air flow direction within the front sub-chamber 208_f is along the A-A' direction between the valve 201 and the valve 202, and an air flow direction within the back sub-chamber 208_b is along the B-B' direction between the valve 203 and the valve 204.

Therefore, the air pulse generating element 20 is able to perform the same function of the air pulse generating element 10 disclosed in U.S. Application No. 16/125,761. Similar to the air pulse generating element 10, the air pulse generating element 20 is able to generate a plurality of air pulses in response to the valve control signals G, H and the membrane driving voltage V_MBN at a pulse rate, where the pulse rate of the plurality of air pulses is higher than a maximum audible frequency. Different from the air pulse generating element 10, the valves 201-204 and the membrane 205 are coplanar, which means that the valves 201-204 and the membrane 205 are fabricated at the same layer. Thereby, a manufacturing cost is reduced and a yield rate is improved.

Note that, the air pulse generating element 20 has four valves disposed by four sides of the membrane, which is not limited thereto. The air pulse generating element of the present invention may comprise two valves disposed by two sides of the membrane.

FIG. 6 is a top view of an air pulse generating element 60 according to an embodiment of the present invention. FIG. 7 is a sectional view diagram of the air pulse generating element 60 through a C- C' line shown in FIG. 6. The air pulse generating element 60 is also a MEMS device.

Similar to the air pulse generating element 20, the air pulse generating element 60 comprises valves 601, 602, a membrane 605, a front faceplate 606 and a back faceplate 607. The valves 601, 602 are fabricated at the same layer (e.g., Layer 3) as the membrane 605. The membrane 605 partitions the chamber 608 into a front sub-chamber 608_f and a back sub-chamber 608_b. In an embodiment shown in FIGs. 6-1, the front faceplate 606 is disposed at the layer 1, the valves 601-604 and the membrane 605 are all fabricated at the layer 3, and the back faceplate 607 is disposed at the layer 5. Openings 611 and 613 are formed within the front faceplate 606, and openings 612 and 614 are formed within the back faceplate 607. The valve 601 is controlled by a valve control signal G' to alternatively seal the openings 611 and 612, which means that the valve 601 may be controlled by the signal G' to seal the opening 611 at a first time and to seal the opening 612 at a second time. Similarly, the valve 602 is controlled by the valve control signal H' to alternatively seal the openings 612 and 613, which means that the valve 601 may be controlled by the signal H' to seal the opening 613 at a third time and to seal the opening 614 at a fourth time.

In the embodiment illustrated in FIG. 6, the valve 601 is disposed by the side s1 of the membrane 605, and the valve 602 is disposed by the side s2 of the membrane 605, where the side s1 and the side s2 are opposite to each other.

In the embodiment illustrated in FIG. 7, the opening 611/613 is at a first direction D1 in related to the valve 601, and the opening 612/614 is at a second direction D2 in related to the valve 602, where the first direction D1 is opposite to the second direction D2. Different from the valves 201-204, the valves 601 and 602 are bi-directional valves, or 2-way valves, which means that the valves 601 and 602 are able to move toward the first direction D1 and also move toward the second direction D2.

Details of the (dynamic) movement of the valves 601, 602 sealing the openings 611-614 are not limited. In an embodiment, the valves 601, 602 may seal the openings 611-614 by a translational movement or a rotational movement, which are illustrated in FIG. 8. In the sub-figure 8a, an embodiment of the translational movement is illustrated. The valve 601/602 may be controlled to move upward to seal the opening 611/613 (at the first/third time) and be controlled to move downward to seal the opening 612/614 (at the second/fourth time). In the sub-figure 8b, an embodiment of the rotational movement is illustrated. The valve 601/602 may comprise caps 62, lever arms 64 and anchors 66. The valve 601/602 may be controlled to rotate clockwise to seal the opening 611/613 (at the first/third time) and be controlled to rotate clockwise to seal the opening 612/614 (at the second/fourth time). In this case, the first/third time may, but not necessarily, be different from the second/fourth time.

Details of the (static) structure of the valve 601/602 are not limited. For example, FIG. 9 illustrates a schematic diagram of a valve 90 according to an embodiment of the present invention. The valve 90 can be used to realize the valve 601 or 602. The valve 90 comprises a cap 92 and actuators 94, 96. The actuators 94, 96 may be disposed on, either a top surface or a bottom surface, or both surfaces, of the valve 90. When the valve 90 is controlled to be move upward, the actuators 94 deform in a concave manner and the actuators 96 deform in a convex manner, as the sub-figure 9a illustrates. When the valve 90 is controlled to be move downward, the actuators 94 deform in a convex manner and the actuators 96 deform in a concave manner, as the sub-figure 9b illustrates.

Furthermore, to shorten the transition period or response time of the valve, the valve may be light weighted. FIG. 9 illustrates a schematic diagram of a valve A0 according to an embodiment of the present invention. The valve A0 can be used to realize the valve 601 or 602. Different from the valve 90, holes may be formed on the valve A0. The holes may be formed by etching. In this case, the response time of the valve A0, in response to the valve signal G'/H', to move either upward or downward, would be shortened, compared to the valve 90.

The air pulse generating element 20/60 may be applied/disposed in a sound producing device. FIG. 11 is a schematic diagram of a sound producing device B0 according to an embodiment of the present invention. The sound producing device B0 comprises a plurality of air pulse generating elements B4 and a control unit B2. The plurality of air pulse generating elements B4 are grouped into air pulse generating groups labeled as P0, P1, P2, and F1-F5. The control unit B2 is configured to generate the valve control signals G/G', H/H' and the membrane driving voltage V_MBN. Details of the sound producing device B0 may be referred to U.S. Application No. 16/125,761, which is not narrated herein for brevity.

In summary, in the air pulse generating element of the present invention, the valves and the membrane are coplanar or fabricated at the same layer, which reduces manufacturing cost and lower the yield rate.