MEMS LOUDSPEAKER ARRANGEMENT COMPRISING A SOUND GENERATOR AND A SOUND AMPLIFIER

Abstract

A MEMS loudspeaker arrangement for generating sound waves in the audible wavelength spectrum includes a housing that defines a sound-conducting channel and a sound outlet arranged at the end of the sound-conducting channel. At least two MEMS loudspeakers are arranged in the interior of the housing so that they generate sound waves through the sound-conducting channel to the sound outlet. One of the MEMS loudspeakers is disposed downstream of the other in the direction of the sound outlet. A control unit is connected to control the MEMS loudspeakers so as to increase the maximum loudness of the MEMS loudspeaker arrangement. The first of the two MEMS loudspeakers is controlled to function as a sound generator for generating an initial wave, and the second MEMS loudspeaker is controlled to function as a sound amplifier for amplifying the initial wave.

Claims

1-16. (canceled)

17. MEMS loudspeaker arrangement for generating sound waves in the audible wavelength spectrum, comprising: a housing that defines an interior with a sound-conducting channel elongating in a downstream direction to an end thereof, the housing further defining a sound outlet disposed at the end of the sound-conducting channel; a first MEMS loudspeaker and a second MEMS loudspeaker disposed in the interior of the housing and downstream of the first MEMS loudspeaker in the direction of the sound outlet, wherein the MEMS loudspeakers are disposed so that the sound waves generated by the MEMS loudspeakers conducts downstream through the sound-conducting channel to the sound outlet; and a control unit connected to control the MEMS loudspeakers and configured for controlling the first MEMS loudspeaker to function as a sound generator for generating an initial wave and the second MEMS loudspeaker to function as a sound amplifier for amplifying this initial wave to form a resulting wave.

18. MEMS loudspeaker arrangement according to claim 17, wherein at least one of the MEMS loudspeakers includes a membrane having a deflection axis that extends in a direction that is disposed transversely to the downstream direction of the sound-conducting channel.

19. MEMS loudspeaker arrangement according to claim 17, wherein the distance between the first MEMS loudspeaker and the sound outlet is greater than the distance between the second MEMS loudspeaker and the sound outlet.

20. MEMS loudspeaker arrangement according to claim 17, wherein the sound-conducting channel between the two MEMS loudspeakers is defined by a pair of side walls that are parallel to each other.

21. MEMS loudspeaker arrangement according to claim 20, wherein the side walls, which are parallel to each other in defining the sound-conducting channel, extend in the longitudinal direction and have the same constant height over their entire lengths.

22. MEMS loudspeaker arrangement according to claim 17, wherein each of the MEMS loudspeakers includes a membrane having a deflection axis that extends in a direction that is disposed transversely to the downstream direction of the sound-conducting channel.

23. MEMS loudspeaker arrangement according to claim 17, wherein the side walls that are parallel to each other in defining MEMS loudspeakers includes a membrane having a deflection axis that extends in a direction that is disposed parallel to each other.

24. MEMS loudspeaker arrangement according to claim 17, wherein the housing further defining a common cavity shared by first MEMS loudspeaker and the second MEMS loudspeaker.

25. MEMS loudspeaker arrangement according to claim 24, wherein the common cavity is disposed in opposition to the sound-conducting channel.

26. MEMS loudspeaker arrangement according to claim 17, wherein each of the MEMS loudspeakers operates in the same frequency range, yet each of the MEMS loudspeakers has a differently sized membrane than the other MEMS loudspeaker.

27. MEMS loudspeaker arrangement according to claim 17, wherein each of the MEMS loudspeakers operates in the same frequency range, yet each of the MEMS loudspeakers has a membrane with a maximum membrane deflection that differs from the maximum membrane deflection of the other MEMS loudspeaker.

28. MEMS loudspeaker arrangement according to claim 17, wherein the first MEMS loudspeaker and the second MEMS loudspeaker share a common membrane.

29. MEMS loudspeaker arrangement according to claim 28, wherein the common membrane is defined by a first membrane area of the first MEMS loudspeaker and a second membrane area of the second MEMS loudspeaker, and wherein the first membrane area is separately controllable from the second membrane area.

30. MEMS loudspeaker arrangement according to claim 28, wherein the common membrane is defined by a first membrane area of the first MEMS loudspeaker and a second membrane area of the second MEMS loudspeaker, and wherein the first membrane area is vibration-isolated from the second membrane area.

31. MEMS loudspeaker arrangement according to claim 17, wherein the first MEMS loudspeaker includes a first membrane and the second MEMS loudspeaker includes a second membrane that is not physically attached to the first membrane, and wherein the first membrane is separately controllable from the second membrane.

32. MEMS loudspeaker arrangement according to claim 17, wherein the first MEMS loudspeaker includes a first membrane and the second MEMS loudspeaker includes a second membrane that is not physically attached to the first membrane, and wherein the first membrane is vibration-isolated from the second membrane.

33. MEMS loudspeaker arrangement according to claim 17, further comprising a third MEMS loudspeaker disposed downstream of the second MEMS loudspeaker in the direction of the sound outlet.

34. MEMS loudspeaker arrangement according to claim 33, wherein the control unit is configured so that the third MEMS loudspeaker is controlled in such a manner to function as a sound amplifier for amplifying the resulting wave to form a twice-amplified wave.

35. MEMS loudspeaker arrangement according to claim 34, wherein the initial wave, the resulting wave and the twice-amplified wave have the same frequency.

36. Method for operating a MEMS loudspeaker arrangement wherein a first MEMS loudspeaker and a second MEMS loudspeaker are disposed upstream of an outlet of the MEMS loudspeaker arrangement, the method comprising the steps of: controlling the first MEMS loudspeaker to generate an initial sound wave; transmitting the initial sound wave as an input to the second MEMS loudspeaker; controlling the second MEMS loudspeaker to receive the initial sound wave; controlling the second MEMS loudspeaker to amplify this initial wave to generate an amplified sound wave; and outputting the amplified sound wave through the outlet of the MEMS loudspeaker arrangement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

[0026] FIG. 1 a longitudinal section through a MEMS loudspeaker arrangement with one MEMS loudspeaker formed as a sound generator and two as sound amplifiers, and

[0027] FIGS. 2a-2c the mode of operation of the MEMS loudspeaker arrangement shown in FIG. 1 for increasing the maximum loudness.

DETAILED DESCRIPTION

[0028] FIG. 1 shows a MEMS loudspeaker arrangement 1, by means of which sound waves can be generated in the audible wavelength spectrum. It comprises a housing 2 that is preferably made at least partially of silicon. Multiple MEMS loudspeakers 3 are arranged in the interior of the housing 2, only one of which is provided with a reference sign for the sake of clarity.

[0029] The housing 2 is preferably formed in several parts in order to facilitate the mounting of the MEMS loudspeakers 3. In this regard, it is conceivable, for example, for the housing 2 to comprise a middle housing part made in particular from silicon and/or a housing frame in which the MEMS loudspeakers 3 are attached in a positively locking, force-fitting and/or firmly bonded manner. In order to provide a closed internal housing space, the middle housing part and/or the housing frame can be closed on its top side and/or bottom side by a cover. In order to avoid the acoustic excitation of the at least one cover, it is advantageous if this is made of a material that is stiffer in comparison to the middle housing part and/or the housing frame, in particular a metal, a ceramic material and/or a composite material.

[0030] In accordance with the embodiment shown in FIG. 1, the MEMS loudspeaker arrangement 13 features a total of three MEMS loudspeakers 3, and variants with only two or more than three MEMS loudspeakers 3 are also conceivable. As can be seen from FIG. 1, such MEMS loudspeakers 3 are formed as separate components. Thus, each of such MEMS loudspeakers 3 comprises a support frame 4, in particular made of silicon. This accommodates a membrane 5 in such a manner that it can be deflected by an electrical control along a membrane deflection axis 6. All of the MEMS loudspeakers 3 operate in the same frequency range. However, contrary to the present exemplary representation, they can have membrane surfaces of different sizes. Furthermore, the MEMS loudspeakers 3 can also have membranes 5 that are able to be deflected to different degrees along the membrane deflection axis 6.

[0031] It is also conceivable that at least two MEMS loudspeakers 3 are not formed as separate components, as shown in FIG. 1, but as a single component. In this case, the MEMS loudspeakers would have a common membrane, whereas each of such MEMS loudspeakers would be assigned with a membrane area that is separately controllable and/or vibration-isolated.

[0032] In accordance with the present embodiment, the MEMS loudspeakers 3 are arranged in succession next to each other. Thus, their membranes 5 can be deflected in the same direction. Furthermore, the MEMS loudspeakers 3 have distances from each other that are equidistant. Their respective membrane deflection axes 6, only one of which is shown for the sake of clarity, are aligned in a manner parallel to each other. Furthermore, the MEMS loudspeakers 3 are arranged in the interior of the housing 2 in such a manner that their respective membrane deflection axis 6 is aligned perpendicular to the longitudinal axis 7 of the housing 2.

[0033] The MEMS loudspeakers 3 have a common sound-conducting channel 8. In accordance with the present embodiment, this extends parallel to the longitudinal axis 7 of the housing 2. The sound-conducting channel 8 is formed in a straight line or is aligned parallel to the longitudinal axis 7. Furthermore, the sound-conducting channel 8 is preferably formed with an essentially cuboid shape. Accordingly, it features even side walls extending in the longitudinal direction. Furthermore, the sound-conducting channel 8 features a constant height and/or width over its entire length.

[0034] The MEMS loudspeakers 3 are arranged in succession one adjacent the other along the sound-conducting channel 8. Accordingly, the membrane deflection axes 6 of the MEMS loudspeakers 3 extend transversely to the elongation direction of the common sound-conducting channel 8.

[0035] As can be seen from the embodiment shown in FIG. 1, the MEMS loudspeakers 3 have a common cavity 9. The cavity 9 is arranged on the side of the MEMS loudspeakers 3 turned away from the sound-conducting channel 8. It is formed at least partially by a housing cavity. The common cavity 9, in particular the housing cavity, is preferably formed as a cuboid and/or extends in the longitudinal direction of the housing 2 beyond all MEMS loudspeakers 3. The cavity 9 is aligned parallel to the sound-conducting channel 8.

[0036] The housing 2 features a sound outlet 10 that is arranged at the end of the common sound-conducting channel 8, such that all MEMS loudspeakers 3 share a single sound outlet 10. In accordance with the present embodiment, the common sound outlet 10 is arranged on a front side 11 of the essentially cuboid-shaped housing.

[0037] Thus, in accordance with the foregoing description, the MEMS loudspeakers 3 are arranged in a manner distributed across the length of the common sound-conducting channel 8, in such a manner that they have sound-conducting channel sections of different lengths to the common sound outlet 10. Thus, the length of the section of the sound-conducting channel 8 between the left MEMS loudspeaker 3 in accordance with the figure and the sound outlet 10 is larger than the section of the sound-conducting channel 8 between the middle and/or right MEMS loudspeaker 3 and the common sound outlet 10. Accordingly, in comparison with the other MEMS loudspeakers 3, the sound waves generated by the left MEMS loudspeaker 3 must travel a longer distance in the sound-conducting channel 8 in order to reach the common sound outlet 10.

[0038] As schematically shown in FIG. 1 for example, the MEMS loudspeakers 3 can be controlled through a control unit 20 in such a manner that a sound wave generated by the first MEMS loudspeaker 3, which is in particular the furthermost from the sound outlet 10, is amplified by the downstream MEMS loudspeakers 3. As a result, the MEMS loudspeaker arrangement 1 features at least one MEMS loudspeaker 3 formed as a sound generator 12 and at least one MEMS loudspeaker 3 formed as a sound amplifier 13, 14. In accordance with the embodiment illustrated in FIG. 1, the MEMS loudspeaker 3 featuring the longest sound-conducting channel section—that is, the left MEMS loudspeaker 3 in accordance with the figure—is formed as a sound generator 12. The MEMS loudspeakers 3 downstream of such sound generator 12 are consequently formed as sound amplifiers 13, 14. In the following, the MEMS loudspeaker 3 adjacent to the sound generator 12 is designated as the first sound amplifier 13, and the MEMS loudspeaker 3 downstream of the first sound amplifier 13 is designated as the second sound amplifier 14.

[0039] The mode of operation of the MEMS loudspeaker arrangement 1 for increasing the maximum loudness is illustrated in FIGS. 2a, 2b and 2c. Accordingly, in accordance with FIG. 2a, the sound generator 12 is controlled at a first point in time, by which a sound wave designated below as the initial wave 15 is generated. For generating the initial wave 15, the membrane 5 of the sound generator 12 accordingly moves into the sound-conducting channel 8, by which a certain air volume is displaced in the direction of the sound outlet 10. It is clear that the sound waves schematically illustrated in FIGS. 2a to 2c do not correspond to the sound wave generated in reality either in their scale or their contours.

[0040] Several parameters concerning the spatial and/or physical configuration of the common sound-conducting channel 8 and/or of the MEMS loudspeakers 3 are known to the control unit 20 (FIG. 1). Thus, the control unit 20 is able to determine a second point in time for controlling the first sound amplifier 13, which is downstream of the sound generator 12, in particular as a function of the first point in time and/or the sound channel length between the sound generator 12 and the first sound amplifier 13.

[0041] In accordance with FIG. 2b, such second point in time is selected by the control unit 20 in such a manner that a first superimposed wave 16 generated by the first sound amplifier 13 is superimposed on the initial wave 15. Thus, the control unit 20 is able to control the first sound amplifier 13 in such a manner that a constructive interference is generated. As a result, the amplitude of the initial wave 15 is increased by the first superimposed wave 16. This generates a first resulting wave 17, which features a higher amplitude compared to the initial wave 15. Accordingly, the amplitude of the first resulting wave 17 corresponds to the sum of the initial wave 15 and the first superimposed wave 16.

[0042] FIG. 2b shows that, at least during the deflection phase of the first sound amplifier 13, the sound generator 12 is still also deflected. This prevents air from being pushed back in the direction of the sound generator 12 when the sound amplifier 13 is deflected. Instead, the membrane 5 of the sound generator 12 that is still controlled forms a space occupier, which ensures that as much air as possible is pressed in the direction of the common sound outlet 10 when the first sound amplifier 13 is deflected.

[0043] According to FIG. 2c, this first resulting wave 17 can be amplified one additional time by the second sound amplifier 14 downstream of the first sound amplifier 13. For this purpose, the control unit 20 determines, in a comparable manner, a third point in time, at which the second sound amplifier 14 is to be controlled. For determining such third point in time, at least the length of the sound-conducting channel 8 between the two sound amplifiers 13, 14 is known to the control unit 20. For the additional amplification of the first resulting wave 17, in accordance with FIG. 2c, this is superimposed by a second superimposed wave 18, by which a second resulting wave 19 is generated.

[0044] By analogy to the preceding description, with this second amplification, the first sound amplifier 13 is also controlled during the deflection of the second sound amplifier 14, such that its membrane acts as a space occupier. Thus, the air is impeded from flowing backward into the sound-conducting channel 8, and instead tends to be pressed in the direction of the sound outlet 10.

[0045] At the same time, as shown in FIG. 2c, the sound generator 12 is once again moved into its initial position, whereas this can take place with a reduced force due to the common cavity 9 and the deflected sound amplifiers 13, 14.

[0046] 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

[0047] 1 MEMS loudspeaker arrangement

[0048] 2 Housing

[0049] 3 MEMS loudspeaker

[0050] 4 Support frame

[0051] 5 Membrane

[0052] 6 Membrane deflection axis

[0053] 7 Longitudinal axis

[0054] 8 Sound-conducting channel

[0055] 9 Cavity

[0056] 10 Sound outlet opening

[0057] 11 Front surface

[0058] 12 Sound generator

[0059] 13 First sound amplifier

[0060] 14 Second sound amplifier

[0061] 15 Initial wave

[0062] 16 First superimposed wave

[0063] 17 First resulting wave

[0064] 18 Second superimposed wave

[0065] 19 Second resulting wave

[0066] 20 control unit