MEMS Acoustic Transducer, and Acoustic Transducer Assembly Having a Stopper Mechanism

Abstract

The invention relates to a MEMS sound transducer (2) for generating and/or detecting sound waves in the audible wavelength spectrum with a membrane carrier (40), a membrane (30) that is connected in its edge area (37) to the membrane carrier, and may vibrate along the z-axis (50) with respect to the membrane carrier, and a stopper mechanism (60), which limits the vibrations of the membrane in at least one direction (51). In accordance with the invention, the MEMS sound transducer is characterized by the fact that the stopper mechanism at least features one reinforcing element (31) that is arranged on one side of the membrane, and an end stop (61) opposite to the reinforcing element, which is spaced at a distance from it in a neutral position of the membrane and against which the reinforcing element abuts at a maximum deflection. The invention also relates to a transducer arrangement (1) with such a MEMS sound transducer (2).

Claims

1. MEMS sound transducer (2) for generating and/or detecting sound waves in the audible wavelength spectrum with a membrane carrier (40), a membrane (30) that is connected in its edge area (37) to the membrane carrier, and may vibrate along the z-axis (50) with respect to the membrane carrier, and a stopper mechanism (60), which limits the vibrations of the membrane in at least one direction (51), characterized in that, the stopper mechanism has at least one reinforcing element (31) that is arranged on one side of the membrane, and an end stop (61) opposite to the reinforcing element, which is spaced at a distance from it in a neutral position of the membrane and against which the reinforcing element abuts at a maximum deflection.

2-16. (canceled)

Description

[0025] Further advantages of the invention are described in the following embodiments. The following is shown:

[0026] FIG. 1 a first embodiment of the sound transducer arrangement and of the MEMS sound transducer in a perspective sectional view,

[0027] FIG. 2 the first embodiment of the sound transducer arrangement and the MEMS sound transducer in a schematic lateral sectional view,

[0028] FIG. 3 the first embodiment of the sound transducer arrangement and the MEMS sound transducer with a membrane that has been swung out in a first direction, in a schematic lateral sectional view,

[0029] FIG. 4 the first embodiment of the sound transducer arrangement and the MEMS sound transducer with a membrane that has been swung out in a second direction, in a schematic lateral sectional view,

[0030] FIG. 5 a second embodiment of the sound transducer arrangement and the MEMS sound transducer in a perspective sectional view,

[0031] FIG. 6 the second embodiment of the sound transducer arrangement and the MEMS sound transducer in a schematic lateral sectional view, and

[0032] FIG. 7 a third embodiment of the sound transducer arrangement and the MEMS sound transducer in a schematic lateral sectional view.

[0033] In the following description of the figures, in order to define the relationships between the various elements, with reference to the locations of objects shown in the figures, relative terms, such as above, below, up, down, over, under, left, right, vertical and horizontal are used. It it self-evident that such a term may change in the event of a deviation from the location of a device and/or element shown in the figures. Accordingly, for example, in the case of an orientation of a device and/or an element shown inverted with reference to the figures, a characteristic that has been specified as above in the following description of the figures would now be arranged below. Thus, the relative terms are used solely for a more simple description of the relative relationships between the individual devices and/or elements described below.

[0034] FIGS. 1 to 4 show a first embodiment of a sound transducer arrangement 1 with a MEMS sound transducer 2 in various views. The MEMS sound transducer 2 is formed for generating and/or detecting sound waves in the audible wavelength spectrum. For this purpose, it has a membrane 30 and a membrane carrier 40.

[0035] The membrane 30 is connected to the membrane carrier 40 in its edge area 37, and is able to vibrate along the z-axis 50 against the membrane carrier 40. Thereby, the z-axis 50 runs essentially perpendicular to the membrane 30.

[0036] The MEMS sound transducer 2 also features a stopper mechanism 60, which is formed to limit the vibrations of the membrane 30 in at least one direction 51. For this purpose, the stopper mechanism 60 features a reinforcing element 31, which is arranged on one side of the membrane 30, here on its underside. On the other hand, the stopper mechanism 60 features an end stop 61 opposite to the reinforcing element 31, which is spaced at a distance from the membrane 30 in a neutral position of the membrane 30, as shown in FIGS. 1 and 2, and against which the reinforcing element 31 abuts at a maximum deflection the membrane 30 in the direction 51, as shown in FIG. 3.

[0037] In this example, the stopper mechanism 60 also comprises a second end stop 62, which limits the vibrations of the membrane 30 along the z-axis 50 in a second direction 52 opposite to the first direction 51. Moreover, the second end stop 62 is also spaced at a distance from the membrane 30 in a neutral position of the membrane 30, as shown in FIGS. 1 and 2, whereas the reinforcing element 31 abuts against the second end stop 62 at a maximum deflection of the membrane 30 in the second direction 52, as shown in FIG. 4. In this case, the membrane 30 is located between the second end stop 62 and the reinforcing element 31.

[0038] Consequently, the membrane 30 according to FIG. 3 is swung downwards or deflected downwards, to the extent that the reinforcing element 31 abuts at the first end stop 61, while, according to FIG. 4, the membrane 30 is swung downwards or deflected upwards, to the extent that the reinforcing element 31 abuts at the second end stop 62 of the stopper mechanism 60.

[0039] As is also evident in particular from FIGS. 1 to 4, the two end stops 61, 62 are arranged in a manner opposite to each other, whereas the reinforcing element 31 is arranged between such two end stops and is spaced at a distance from them. Thereby, the second end stop 62 is arranged on an upper housing part 81, which is arranged above the membrane 30, and in particular in a sound-conducting channel 92 formed by the upper housing part 81.

[0040] On the other hand, the first end stop 61 is arranged on a carrier substrate 71 of a MEMS actuator 70 or is formed by one side of the carrier substrate 71. This MEMS actuator 70 is arranged below the membrane 30 and/or is essentially parallel to it. It works together with the membrane 30 to convert electrical signals into acoustically perceptible sound waves or vice versa. For this purpose, the MEMS actuator 70 comprises an actuator structure 73. This is preferably designed to be piezoelectric. Furthermore, the actuator structure 73 is arranged on a side of the carrier substrate 71 turned away from the membrane 30. In this example, the front surface 72 of the carrier substrate 71 of the MEMS actuator 70 turned towards the membrane 30 is formed as an end stop 61. Unlike that shown here, however, the first end stop 61 could also be formed on a housing part, such as the middle housing part 83 and/or on a circuit board, such as the circuit board 84. In the present case, the reinforcing element 31 is fastened to the membrane 30 on the side turned towards the MEMS actuator 70. In addition or alternatively, the reinforcing element 31 or an additional reinforcing element could, in principle, also be fastened to the membrane 30 on the side turned away from the MEMS actuator 70. In particular, the reinforcing element 31 features an end stop surface 33 corresponding to the end stops 61, 62.

[0041] In addition to the membrane 30, the membrane carrier 40, the MEMS actuator 70, and the two housing parts 81, 83 of the MEMS transducer 2, the sound transducer arrangement 1 also includes a circuit board 84 and a lower housing part 89. An AS IC 85 is fully embedded in the circuit board 84. In addition to the ASIC, other passive components, such as electrical resistors and/or I/O contacts, may be embedded in and/or arranged on the circuit board.

[0042] The circuit board 84 features a recess 86 which extends fully through the circuit board and has two openings 87, 88. The MEMS actuator 70 is arranged at the first opening 87 of the recess 86. The lower housing part 89 is arranged at the second opening 88 of the recess 86 to form a closed cavity 91. Thus, the circuit board 84 is arranged between the MEMS actuator 70 and the lower housing part 89.

[0043] The MEMS sound transducer 2, and in particular the MEMS actuator 70, is connected to the ASIC 85 with electrical contacts that are not further shown in the figures. Thus, the MEMS sound transducer 2 can thus be controlled or operated by means of ASIC 85. For example, if the MEMS transducer 2 is to function as a loudspeaker, it can be excited by means of the ASIC 85 in such a manner that, through the MEMS actuator 70, the membrane 30 for generating sound energy is vibrated against the membrane carrier 40. The term cavity is to be understood as an empty space by means of which the sound pressure of the MEMS transducer can be reinforced. Since the cavity 91 is already partially formed by the recess 86 of the circuit board 84, the sound transducer arrangement 1 can be formed in manner that saves installation space to a high degree, but with a relatively large acoustically effective cavity volume, since the empty space provided by the lower housing part 89 for forming the cavity 91 can now turn out to be smaller. The housing parts 81, 83, and in particular the lower housing part 89, preferably feature a material that is different from the circuit board 84. Alternatively, at least one of the housing parts 81 could also be a component of the circuit board 84.

[0044] The sound transducer arrangement 1 has an essentially rectangular basic shape, and is thus simple and cost-effective to manufacture, and is suitable for numerous applications. The sound transducer arrangement 1 is also constructed in a sandwich-like manner; that is, the lower housing part 89, the circuit board 84 and the MEMS sound transducer 2 are arranged in a manner stacked on top of each other. Thereby, the MEMS sound transducer 2, the circuit board 84 and the lower housing part 89 all have the same outer diameter. Alternatively, however, the sound transducer arrangement 1 can, in principle, also feature a basic shape (in particular, a round basic shape).

[0045] The membrane 30, which consists, in particular, of silicone, is fastened in its edge area 37 in the fastening area 41 of the membrane carrier 40, whereas the fastening area 41 is arranged in a manner spaced at a distance from the MEMS actuator 70 and its carrier substrate 71 in the x-, y- and z-directions. In this case, the membrane carrier 40 is formed by the upper housing part 81 and the middle housing part 83, whereas the fastening area is located between the two housing parts 81, 83, and the membrane is thus fastened between such two housing parts. The membrane carrier 40 is formed with frame-like design and surrounds the membrane 30. Unlike that shown here, however, the membrane carrier 40 could also be at least partially formed by a circuit board, such as the circuit board 84.

[0046] Adjacent to its edge area 37, the membrane 30 features an outer elastic area 38, formed in the present case in particular as a bulge 39, and an inner reinforced area 32, in which the reinforcing element 31 is arranged. Thereby, the reinforced area 32 or the reinforcing element 31, as the case may be, is arranged immediately adjacent to the elastic area 38. The elastic area 38 allows the membrane 30 to vibrate against the membrane carrier 40, and in particular the inner-reinforced area 32 against the outer edge area 37. In this case, the reinforcing element 31 is made of a metal and/or is formed with a plate-shaped design, whereas, as in the present case, it preferably extends over the entire reinforced area 32 and is glued to the membrane 30. In this case, the end stop surface 33 that is provided by the reinforcing element and corresponds to the stops 61, 62 is formed with frame-like design and is arranged immediately adjacent to the elastic area 38, which is likewise formed with frame-like design.

[0047] Moreover, the first end stop 61 and the second end stop 62 are formed with frame-like design, in this example corresponding to the end stop surface 33. Thereby, the carrier substrate 71, which provides the first end stop 61 on its front surface 72, surrounds the actuator structure 73 in a frame-like manner, while the upper housing part 81 features a projection 82, which surrounds the acoustic inlet/outlet opening 93 of the sound-conducting channel 92 in a frame-like manner and provides the second end stop 62.

[0048] In the interior of the frame-shaped end stop surface 33, the reinforcing element 31 of the membrane 30 features a coupling surface 35. Thereby, the end stop surface 33 and the coupling surface 35 are spaced at a distance from each other in the z-direction and are connected to each other through an intermediate area 34 of the reinforcing element 31, which is funnel-shaped in this case. Since the reinforcing element 31 is glued to the membrane 30, the membrane 30 accordingly has a funnel-like shape. In the area of the coupling surface 35, the reinforcing element 31 is connected to the actuator structure 73 of the MEMS actuator 70 through a coupling element 74. In the present case, the carrier substrate 71 and the coupling element 74 are produced from the same substrate, in particular a silicon substrate. They also feature the same thickness. Unlike the one shown here, alternatively or in addition to the coupling element 74, an adapter element for connecting to the actuator structure 73 can be used.

[0049] FIGS. 5 to 7 show additional embodiments of the sound transducer arrangement 1 and the MEMS sound transducer 2, whereas, essentially, the differences with respect to the first embodiment already described are discussed. Thus, with FIGS. 5 to 7 and the following description of the additional embodiments, the same reference signs are used for characteristics that are identical and/or at least comparable when compared to the first embodiment shown in FIGS. 1 to 4, in terms of their design and mode of action. To the extent that such characteristics are not explained once again in detail, their design and mode of action correspond to the characteristics described above. The differences described below can be combined with the characteristics of the respective preceding and subsequent embodiments.

[0050] FIGS. 5 and 6 show a second embodiment of the sound transducer arrangement 1 and the MEMS sound transducer 2 in different views. With the second embodiment, the upper housing part 81 is to be mentioned as a major difference from the first embodiment shown in FIGS. 1 to 4. In this case, the upper housing part 81 forms a sound-conducting channel 92 with an acoustic inlet / outlet opening 93, which is arranged laterally on the outer surface of the MEMS sound transducer 2 or the sound transducer arrangement 1, as the case may be. The housing part 81 provides, in particular, additional protection for the membrane 30, since it provides a cover against the environment.

[0051] However, no second end stop is provided in this embodiment; that is, no end stop for the reinforcing element 31 of the membrane 30 is arranged on the upper housing part 81. Furthermore, in this case, the upper housing part 81 is not a component of the membrane carrier 40. This is formed solely by the middle housing part 83, such that the membrane 30 is fastened solely to the middle housing part 83. The upper and lower housing parts 81, 89 have a larger outer diameter in comparison to the first embodiment, by which the base surface of the sound transducer arrangement 1 is enlarged. In addition, in this example, the upper housing part 81 is not arranged on the middle housing part 83, but on the lower housing part 89, and is connected to this, such that such two housing parts together form a housing that surrounds the remaining components of the transducer arrangement 1 or the MEMS sound transducer 2, as the case may be.

[0052] FIG. 7 shows a third embodiment of the sound transducer arrangement 1 and the MEMS sound transducer 2. With this, the upper housing part 81 within the sound-conducting channel 92 features a projection 82, which is arranged above the membrane 30, and the reinforcing element 31 of the membrane 30 forms the second end stop 62.

[0053] This invention is not limited to the illustrated and described embodiments. Variations within the scope of the claims, just as the combination of characteristics, are possible, even if they are illustrated and described in different embodiments.

LIST OF REFERENCE SIGNS

[0054] 1 Transducer arrangement

[0055] 2 MEMS transducer

[0056] 30 Membrane

[0057] 31 Reinforcing element

[0058] 32 Reinforced area

[0059] 33 End stop surface

[0060] 34 Intermediate area

[0061] 35 Coupling surface

[0062] 37 Edge area

[0063] 38 Elastic area

[0064] 39 Bulge

[0065] 40 Membrane carrier

[0066] 41 Fastening area

[0067] 50 z-axis

[0068] 51 First direction

[0069] 52 Second direction

[0070] 60 Stopper mechanism

[0071] 61 First end stop

[0072] 62 Second end stop

[0073] 70 MEMS actuator

[0074] 71 Carrier substrate

[0075] 72 Front surface

[0076] 73 Actuator structure

[0077] 74 Coupling element

[0078] 81 Housing part

[0079] 82 Projection

[0080] 83 Housing part

[0081] 84 Circuit board

[0082] 85 ASIC

[0083] 86 Recess

[0084] 87 First opening

[0085] 88 Second opening

[0086] 89 Housing part

[0087] 91 Cavity

[0088] 92 Sound-conducting channel

[0089] 93 Acoustic inlet/outlet opening