Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
  • H10N30/204—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders
  • H10N30/2041—Beam type
  • H10N30/2042—Cantilevers, i.e. having one fixed end
  • H10N30/2044—Cantilevers, i.e. having one fixed end having multiple segments mechanically connected in series, e.g. zig-zag type
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
  • H10N30/204—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders
  • H10N30/2041—Beam type
  • H10N30/2042—Cantilevers, i.e. having one fixed end
  • H10N30/2046—Cantilevers, i.e. having one fixed end adapted for multi-directional bending displacement
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
  • H04R2201/003—Mems transducers or their use

Definitions

• the present disclosure relates to micro-electro-mechanical systems (MEMS). More specifically, the present disclosure relates to a MEMS actuation device and method as well as a loudspeaker comprising such a MEMS actuation device.
• MEMS micro-electro-mechanical systems
• a MEMS loudspeaker has been disclosed, for instance, in A. Arevalo and I. G. Foulds, "MEMS acoustic pixel", in Proceedings of the 2014 COMSOL Conference, Cambridge, 2014.
• the MEMS loudspeaker disclosed by A. Arevalo and I. G. Foulds makes use of four piezoelectrically driven cantilever beams for displacing a circular diaphragm out of its resting position along the axis normal to the diaphragm plane.
• each cantilever beam piezoelectric material e.g. lead zirconate titanate (PZT)
• PZT lead zirconate titanate
• This cantilever beam structure deforms due to a voltage between the two electrodes that evokes a piezoelectric effect determined by the piezoelectric coefficient d3i of the piezoelectrical material.
• the contraction or expansion of the piezoelectric material depending on the sign of the applied voltage, yields a flexural mode deflection of the cantilever beam. Since the contraction (or expansion) of the piezoelectric layer would occur homogeneously across the full area (in theory), the resulting flexural mode has constant curvature.
• the largest deflection of a cantilever beam occurs at the furthest end from the suspension and therefore, assuming the resting position of a cantilever beam is horizontal, the tangent at the furthest point from the suspension has the largest angle to the horizontal plane. If the cantilever beam is intended as a vertical actuator/motor for a loudspeaker diaphragm to be attached to that point this may pose a problem, because for large displacements the resulting large angle can introduce a significant stress to the diaphragm that attaches to the cantilever beam.
• the actuation device comprises a support structure and a cantilever beam extending from a first end fixed to the support structure to a second free end.
• the free end of the cantilever beam is an end not fixed to any support structure.
• the cantilever beam comprises a first piezoelectrical portion facing the first fixed end of the cantilever beam, e.g. arranged in the vicinity of or at the first fixed end of the cantilever beam and a second piezoelectrical portion facing the second free end of the cantilever beam, e.g. arranged in the vicinity of or at the second fixed end of the cantilever beam.
• the first piezoelectrical portion and the second piezoelectrical portion may comprise a piezoelectrical material, such as lead zirconate titanate (PZT).
• the cantilever beam comprises a plurality of electrodes configured to apply a first electrical field to the first piezoelectrical portion and a second electrical field to the second piezoelectrical portion such that, when applying the first electrical field to the first piezoelectrical portion and the second electrical field to the second piezoelectrical portion, the first electrical field forces the first piezoelectrical portion to bend in a first lateral direction and the second electrical field forces the second piezoelectrical portion to bend in a second lateral direction different from the first lateral direction, thereby causing lateral movement of the second free end of the cantilever beam.
• the first piezoelectrical portion and the second piezoelectrical portion allow providing a cantilever beam having in a bended state a S-shape with the same tangle agent at the second free end of the cantilever beam as at the first fixed end of the cantilever beam.
• the first lateral direction and the second lateral direction define an obtuse or a straight angle, i.e. an angle of 180°.
• the obtuse angle between the first lateral direction and the second lateral direction may be larger than 150°, more preferable larger than 160°, even more preferable larger than 170° and most preferable larger than 175°.
• the actuation device further comprises an electrical power source configured to drive the plurality of electrodes to apply the first electrical field to the first piezoelectrical portion and the second electrical field to the second piezoelectrical portion.
• the actuation device may provide a motor.
• the first piezoelectrical portion of the cantilever beam is polarized in a first polarization direction and the second piezoelectrical portion of the cantilever beam is polarized in a second polarization direction opposite to the first polarization direction, wherein the first electrical field is directed in the same direction as the second electrical field.
• the first piezoelectrical portion of the cantilever beam and the second piezoelectrical portion of the cantilever beam are polarized in the same direction, wherein the first electrical field is directed in the opposite direction of the second electrical field.
• the cantilever beam comprises a plurality of parallel layers extending longitudinally along the cantilever beam, wherein the first piezoelectrical portion and the second piezoelectrical portion define a first layer of the plurality of parallel layers.
• this allows to efficiently manufacture the MEMS actuation device.
• the plurality of electrodes define a second layer and a third layer of the plurality of parallel layers, wherein the first layer of the plurality of parallel layers defined by the first piezoelectrical portion and the second piezoelectrical portion is arranged between the second layer and the third layer of the plurality of parallel layers defined by the plurality of electrodes.
• the plurality of parallel layers further comprise a substrate layer, wherein the first layer, the second layer and/or the third layer of the plurality of parallel layers are arranged on the substrate layer.
• the first layer of the plurality of layers comprises a recess or gap between the first piezoelectrical portion and the second piezoelectrical portion for separating the first piezoelectrical portion and the second piezoelectrical portion.
• the cantilever beam has a cuboid shape, wherein the plurality of layers extend substantially parallel to one of the surfaces of the cuboid cantilever beam.
• the actuation device comprises one or more further cantilever beams, wherein the further cantilever beam extends from a first end fixed to the second free end of the cantilever beam to a second free end of the further cantilever beam.
• the further cantilever beam comprises a third piezoelectrical portion facing the first fixed end of the further cantilever beam and a fourth piezoelectrical portion facing the second free end of the further cantilever beam.
• the further cantilever beam comprises a further plurality of electrodes configured to apply a third electrical field to the third piezoelectrical portion and a fourth electrical field to the fourth piezoelectrical portion such that, when applying the third electrical field to the third piezoelectrical portion and the fourth electrical field to the fourth piezoelectrical portion, the third electrical field forces the third piezoelectrical portion to bend in the first lateral direction and the fourth electrical field forces the fourth piezoelectrical portion to bend in the second lateral direction, thereby causing lateral movement of the second free end of the further cantilever beam.
• an actuation device with a daisy-chained arrangement of identical or similar cantilever beams is provided which allows increasing the net displacement of the second free end of the final cantilever beam in the daisy-chain of cantilever beams.
• a loudspeaker comprises at least one actuation device according to the first aspect. Moreover, the loudspeaker comprises a diaphragm connected to the second free end of the cantilever beam of the at least one actuation device, wherein an oscillating displacement of the second free end of the cantilever beam results in an oscillating displacement of the diaphragm for generating an acoustic signal.
• the support structure is a rectangular frame with four sides, wherein the loudspeaker comprises four actuation devices according to the first aspect and wherein a cantilever beam of a respective actuation device of the four actuation devices is fixed with one end to a respective side of the rectangular frame and with another end to the diaphragm.
• the loudspeaker further comprises a control unit configured to apply a driving signal to the at least one actuation device.
• the control unit is configured to apply one or more driving signals to the plurality of electrodes.
• a method of actuating an actuation device comprising a support structure and a cantilever beam extending from a first end fixed to the support structure to a second free end and wherein the cantilever beam comprises a first piezoelectrical portion facing the first fixed end of the cantilever beam and a second piezoelectrical portion facing the second free end of the cantilever beam.
• the method comprises the step of applying a first electrical field to the first piezoelectrical portion and a second electrical field to the second piezoelectrical portion such that, when applying the first electrical field to the first piezoelectrical portion and the second electrical field to the second piezoelectrical portion, the first electrical field forces the first piezoelectrical portion to bend in a first lateral direction and the second electrical field forces the second piezoelectrical portion to bend in a second lateral direction different from the first lateral direction, thereby causing lateral movement of the second free end of the cantilever beam.
• the actuating method according to the third aspect of the present disclosure can be performed by the actuating device according to the first aspect of the present disclosure.
• further features of the actuating method according to the third aspect of the present disclosure result directly from the functionality of the actuating device according to the first aspect of the present disclosure and its different implementation forms described above and below.
• Fig. 1 is a schematic cross-sectional view illustrating the bending behavior of a cantilever beam of an actuation device according to an embodiment
• Fig. 2a is a schematic cross-sectional view of a cantilever beam of an actuation device according to an embodiment
• Fig. 2b shows several schematic cross-sectional views illustrating the bending behavior of a cantilever beam of an actuation device according to an embodiment in response to different driving voltages;
• Fig. 2c is a diagram illustrating the stress distribution within a bended cantilever beam of an actuation device according to an embodiment
• Fig. 3a is a schematic perspective view of a loudspeaker according to an embodiment including four actuation devices according to an embodiment;
• Fig. 3b is a diagram illustrating the stress distribution within the bended cantilever beams of the loudspeaker of figure 3a according to an embodiment
• Fig. 3c is a diagram illustrating the displacement of the bended cantilever beams of the loudspeaker of figure 3a according to an embodiment
• Fig. 3d is a schematic diagram illustrating the wiring of the four actuation devices of the loudspeaker of figure 3a according to an embodiment
• Fig. 4a is a schematic top view of an actuation device according to an embodiment including two daisy-chained cantilever beams;
• Fig. 4b is a diagram illustrating the displacement of the daisy-chained cantilever beams of the actuation device of figure 4a in a bended position according to an embodiment
• Fig. 5 is a schematic perspective view of a loudspeaker according to an embodiment including four actuation devices according to the embodiment shown in figure 4a;
• Fig. 6 is a diagram illustrating an actuation method according to an embodiment.
• a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa.
• a corresponding device may include one or a plurality of units, e.g. functional units, to perform the described one or plurality of method steps (e.g. one unit performing the one or plurality of steps, or a plurality of units each performing one or more of the plurality of steps), even if such one or more units are not explicitly described or illustrated in the figures.
• a specific apparatus is described based on one or a plurality of units, e.g.
• a corresponding method may include one step to perform the functionality of the one or plurality of units (e.g. one step performing the functionality of the one or plurality of units, or a plurality of steps each performing the functionality of one or more of the plurality of units), even if such one or plurality of steps are not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless specifically noted otherwise.
• FIG. 1 is a schematic diagram illustrating a MEMS actuation device 100 according to an embodiment.
• the actuation device 100 comprises a support structure 110 and a flexible cantilever beam 101 extending from a first end 101a fixed to the support structure 110 to a second free end 101b.
• figure 1 shows the cantilever beam 101 in a bended position, i.e. when forces are acting on the cantilever beam 101 to displace it out of its resting position (shown for instance in figure 2b).
• the flexible cantilever beam 101 may have a substantially cuboid shape in its resting position.
• the tangent 120b defined by the second free end 101b of the cantilever beam 101 is substantially parallel to the tangent 120a defined by the first fixed end 101a of the cantilever beam 101.
• this bending behaviour of the cantilever beam 101 resulting in the S- shape of the cantilever beam 101 shown in figure 1 may be achieved by a piezoelectric layer 102a, 102b interrupted halfway along the cantilever beam 101 and polarized in opposite directions.
• a first piezoelectric portion 102a closer to the support structure 110 will laterally expand, thus bending the cantilever beam 101 upwards, while a second piezoelectric portion 102b will laterally contract and create a curvature in the second half of the cantilever beam 101 that opposes that of the first half of the cantilever beam 101. If both piezoelectric portions 102a, 102b have the same size and strength of polarization, then the resulting tangent 120b defined by the second free end 101b of the cantilever beam 101 is parallel to that when in resting position.
• the cantilever beam 101 comprises the first piezoelectrical portion 102a facing the first fixed end 101a of the cantilever beam 101 and the second piezoelectrical portion 102b facing the second free end 101b of the cantilever beam 101.
• the first piezoelectrical portion 102a and the second piezoelectrical portion 102b may comprise a piezoelectrical material, such as lead zirconate titanate (PZT).
• the first piezoelectrical portion 102a and the second piezoelectrical portion 102b extend right up to the first fixed end 101a and the second free end 101b of the cantilever beam 101 and, thus, face the first fixed end 101a and the second free end 101b, respectively.
• the first piezoelectrical portion 102a may face the first fixed end 101a and/or the second piezoelectrical portion 102b may face the second free end 101b of the cantilever beam 101 by being arranged in the vicinity of the first fixed end 101a and/or the second free end 101b of the cantilever beam 101.
• the cantilever beam 101 may comprise some non-piezoelectrical material located between the first fixed end 101a and the first piezoelectrical portion 102a and/or between the second free end 101b and the second piezoelectrical portion 102b.
• the cantilever beam 101 comprises a plurality of electrodes, namely top electrodes 103a, 103b and a bottom electrode 105 configured to apply a first electrical field to the first piezoelectrical portion 102a and a second electrical field to the second piezoelectrical portion 102b of the cantilever beam 101.
• the actuation device 101 may further comprise an electrical power source (not shown in the figures) wired to the top electrodes 103a, 103b and the bottom electrode 105.
• the top electrodes 103a, 103b and the bottom electrode 105 are configured to apply the first electrical field to the first piezoelectrical portion 102a and the second electrical field to the second piezoelectrical portion 102b of the cantilever beam 101 such that the first electrical field forces the first piezoelectrical portion 102a to bend in a first lateral direction (indicated for a given point in time by the arrow A in figure 1) and the second electrical field forces the second piezoelectrical portion 102b to bend in a second lateral direction (indicated for a given point in time by the arrow B in figure 1) different from the first lateral direction A, thereby causing lateral movement of the second free end 101b of the cantilever beam 101.
• the first lateral direction A and the second lateral direction B define an obtuse or a straight angle, i.e. an angle of 180°.
• the obtuse angle between the first lateral direction A and the second lateral direction B may be larger than 150°, more preferable larger than 160°, even more preferable larger than 170° and most preferable larger than 175°.
• figure 1 shows the cantilever beam 101 in a bended position, i.e. when the first electrical field is applied to the first piezoelectrical portion 102a and the second electrical field is applied to the second piezoelectrical portion 102b of the cantilever beam 101.
• Figure 2b illustrates the bending behaviour of the cantilever beam 101 for three different points in time, when time varying electrical fields are applied to the first piezoelectrical portion 102a and the second piezoelectrical portion 102b of the cantilever beam 101.
• the electrical power source of the actuation device 100 may be configured to apply electrical fields periodically varying in time to the first piezoelectrical portion 102a and the second piezoelectrical portion 102b of the cantilever beam 101, such as electrical fields with a sinusoidal time dependence.
• Figure 2c illustrates the stress distribution within the cantilever beam 101 according to an embodiment in one of its bended positions.
• the free end 101b of the cantilever beam 101 is exposed to a reduced stress level.
• the cantilever beam 101 comprises a plurality of parallel material layers extending longitudinally along and substantially parallel to the top and bottom surfaces of the cuboid shaped cantilever beam 101.
• a first layer is defined by the first piezoelectrical portion 102a and the second piezoelectrical portion 102b of the cantilever beam 101.
• the first layer defined by the first piezoelectrical portion 102a and the second piezoelectrical portion 102b is arranged between a second layer defined by the top electrodes 103a, 103b and a third layer defined by the bottom electrode 105.
• the plurality of layers of the cantilever beam 101 may further comprise a substrate layer 107 configured to support the other layers of the cantilever beam 101, namely from bottom to top the third layer defined by the bottom electrode 105, the first layer defined by the first piezoelectrical portion 102a and the second piezoelectrical portion 102b and the second layer defined by the top electrodes 105a, 105b.
• the first layer defined by the first piezoelectrical portion 102a and the second piezoelectrical portion 102b of the cantilever beam 101 and/or the second layer defined by the top electrodes 103a, 103b may comprise a recess or gap 104, for instance, between the first piezoelectrical portion 102a and the second piezoelectrical portion 102b for separating the first piezoelectrical portion 102a and the second piezoelectrical portion 102b.
• the layered structure of the cantilever beam 101 shown in figure 2a may be defined by one or more of the following parameters, which may be adjusted depending on the specific use case: number of cantilever beams 101 n (as will be described in more detail further below), cantilever beam 101 length S, cantilever beam 101 width L, substrate layer 107 thickness d s , electrode 103a, 103b and 105 thicknesses d ei and d e 2, piezoelectric layer 102a, 102b thickness d p , and the size of the gap 104 between the piezoelectric patches g p .
• the cantilever beam 101 may have a length S of about 10550 micrometers and a width L of about 1450 micrometers.
• the combination of one or more of these parameters may affect the weight and/or flexibility of the cantilever beam 101.
• all layers may extend along the full length S (minus the size of the gap 104 g p if present) and the full width L of the cantilever beam 101. For achieving a large displacement it may be advantageous to keep the size of the gap g p 104 as small as possible.
• the actuation device 100 may be implemented according to the following embodiments.
• the first piezoelectrical portion 102a of the cantilever beam 101 is polarized in a first polarization direction (for instance vertically upwards) and the second piezoelectrical portion 102b of the cantilever beam 101 is polarized in a second polarization direction (for instance vertically downwards) opposite to the first polarization direction.
• the electrical power source of the actuation device 100 may be configured to drive the top electrodes 103a, 103b and the bottom electrode 105 such that the first electrical field applied to the first piezoelectrical portion 102a is directed substantially in the same direction as the second electrical field applied to the second piezoelectrical portion 102b of the cantilever beam 101.
• the first piezoelectrical portion 102a of the cantilever beam 101 and the second piezoelectrical portion 102b of the cantilever beam 101 may be polarized substantially in the same direction (for instance vertically upwards).
• the electrical power source of the actuation device 100 may be configured to drive the top electrodes 103a, 103b and the bottom electrode 105 such that the first electrical field applied to the first piezoelectrical portion 102a is directed substantially in the opposite direction of the second electrical field applied to the second piezoelectrical portion 102b of the cantilever beam 101.
• Figure 3a is a schematic perspective view of a MEMS loudspeaker 300 according to an embodiment including four actuation devices 100 according to an embodiment, each of the four actuation devices 100 comprising a cantilever beam 101 as described above.
• the support structure 110 of the MEMS loudspeaker 300 is provided by a rectangular frame 110 with four sides, wherein the first end 101b of each of the four cantilever beams 101 is fixed to a respective inner side of the rectangular support frame 110.
• the MEMS loudspeaker 300 further comprises a flexible rectangular diaphragm 310 connected at respective connection portions 311 of the flexible diaphragm 310 to the respective second free end 101b of each of the four cantilever beams 101 such that an oscillating displacement of each of the second free ends 101b of each of the four cantilever beams 101 results in an oscillating displacement of the diaphragm 310 for generating an acoustic signal (i.e. air pressure waves).
• the four cantilever beams 101 are separated from the diaphragm 310 along most of their length, except for the connection portions 311 connecting the second free end 101b of each cantilever beam 101 to the diaphragm 310.
• the top electrodes 103a, 103b have been removed in order to clearly show the configuration and arrangement of the first and second piezoelectrical portion 102a, 102b of each cantilever beam 101.
• Figure 3b illustrates the stress distribution (measured in Newton per square meter) within the diaphragm 310 and the bended cantilever beams 101 of the loudspeaker 300 of figure 3a during such an oscillating displacement of the diaphragm 310
• Figure 3c illustrates the displacement of the bended cantilever beams 101 of the loudspeaker 300 relative to their rest positions.
• the connection portions 311 of the diaphragm 310 are exposed to reduced stress levels.
• the diaphragm 310 in the middle of the loudspeaker 300 represents a stiff piston that is moved out of its resting position through the force created by the cantilever beams 101 of the actuation devices 100.
• the sign of the electrical driving signal (e.g.) voltage By changing the sign of the electrical driving signal (e.g.) voltage, deflections of the diaphragm 310 to either side of the resting position shown in figure 3a are possible.
• the MEMS loudspeaker 300 may further comprise a control unit configured to apply a driving signal (based, for instance, on an audio signal) to each of the four actuation devices 100, in particular the respective electrical power source thereof.
• a driving signal based, for instance, on an audio signal
• the electrical power sources of each of the four actuation devices 100 may be provided by a single electrical power source connected to the control unit.
• Figure 3d illustrates a possible wiring 320 for connecting the electrodes 103a, 103b and 105 of the cantilever beams 101 of the four actuation devices 100 of the loudspeaker 300 of figure 3a to the electrical power source.
• control unit of the loudspeaker 300 is configured to drive all four cantilever beams 101 with the same driving signal. This allows preventing the diaphragm 310 to be excited into rocking modes, which would negatively affect the acoustic performance of the loudspeaker 300.
• the driving signal is applied in parallel as a voltage between the bottom 105 and top electrodes 103a, 103b of all four cantilever beams 101.
• the wiring 320 may comprise a plurality of wire bonds 320a, 320b, 320c as illustrated in figure 3d. In the embodiment shown in figure 3d, all bottom electrodes 105 are connected to ground.
• Figures 4a and 4b illustrate a further embodiment of the actuation device 100, wherein the actuation device 100 in addition to the cantilever beam 101 described above comprises a further cantilever beam 10T, which in an embodiment may have the same structure as the cantilever beam 101 (for instance the multi-layer structure illustrated in figure 2a).
• the cantilever beam 101 and the further cantilever beam 10T are arranged and connected in a kind of daisy-chained arrangement.
• the further cantilever beam 10T extends from a first end 101a' fixed via a connection portion 401 (referred to as "landing" 401 in figure 4a) to the second free end 101b of the cantilever beam 101 to a second free end 101b' (referred to as "displacing end” in figure 4a) of the further cantilever beam 10T.
• the cantilever beam 101 and the further cantilever beam 10T extend substantially parallel but with a lateral shift (similar to a multi-floor staircase in a building).
• the further cantilever beam 10T may comprise a first piezoelectrical portion 102a' (which defines a third piezoelectrical portion 102a' of the actuation device 100) facing the first end 101a' of the further cantilever beam 10T fixed to the cantilever beam 101 and a second piezoelectrical portion 102b' (which defines a fourth piezoelectrical portion 102b' of the actuation device 100) facing the second free end 101b' of the further cantilever beam 101'.
• the further cantilever beam 101' may comprise a further plurality of electrodes configured to apply a third electrical field to the third piezoelectrical portion 102a' and a fourth electrical field to the fourth piezoelectrical portion 102b' such that, when applying the third electrical field to the third piezoelectrical portion 102a' and the fourth electrical field to the fourth piezoelectrical portion 102b', the third electrical field forces the third piezoelectrical portion 102a' to bend in the first lateral direction (i.e.
• the fourth electrical field forces the fourth piezoelectrical portion 102b' to bend in the second lateral direction (i.e. in the same direction as the second piezoelectrical portion 102b of the cantilever beam 101), thereby causing lateral movement of the second free end 101 b' of the further cantilever beam 101'.
• Figure 4b illustrates the displacement relative to the rest position of the cantilever beam 101 and the further cantilever beam 101' of figure 4a in a bended position, i.e. when the cantilever beam 101 and the further cantilever beam 101' have been displaced from their resting positions.
• the second free end 101b' of the further cantilever beam 10T is exposed to reduced stress levels, while the daisy-chained arrangement of the cantilever beam 101 and the further cantilever beam 10T allows larger displacements of the second free end 101b' of the further cantilever beam 10T (compared to the embodiment shown in figures 2a, 2b and 2c having a single cantilever beam).
• the actuation device 100 may comprise more than the two cantilever beams 101, 10T illustrated in figures 4a and 4b, wherein each further cantilever beam is mounted in a daisy-chained arrangement with its first fixed end to a second free end of a preceding cantilever beam.
• FIG. 5 is a schematic perspective view of the loudspeaker 300 according to an embodiment comprising four actuation devices based on the embodiment of the actuation device 100 illustrated in figures 4a and 4b.
• the loudspeaker 300 shown in figure 5 comprises as the support structure 110 a rectangular frame 110 with four sides, wherein the first end 101b of each of the four cantilever beams 101 is fixed to a respective inner side of the rectangular support frame 110.
• the flexible diaphragm 310 is connected at the respective connection portions 311 of the flexible diaphragm 310 to the respective second free end 101b' of each further cantilever beam 101' such that an oscillating displacement of each of the second free ends 101 b' of each of the further cantilever beams 101 ' results in an oscillating displacement of the diaphragm 310 for generating an acoustic signal (i.e. air pressure waves).
• an acoustic signal i.e. air pressure waves
• the further cantilever beam 101' (fixed to the diaphragm 310) may have a smaller longitudinal extension than the cantilever beam 101 (fixed to the rectangular support frame 110).
• the MEMS loudspeaker 300 shown in figure 5 is capable of generating larger displacements of the diaphragm 310 than the loudspeaker shown in figure 3a.
• Figure 6 is a diagram illustrating a method 600 of actuating an actuation device 100 according to an embodiment, wherein the actuation device 100 comprises a support structure 110 and a cantilever beam 101 extending from a first end 101a fixed to the support structure 110 to a second free end 101b and wherein the cantilever beam 101 comprises a first piezoelectrical portion 102a facing the first fixed end 101a of the cantilever beam 101 and a second piezoelectrical portion 102b facing the second free end 101b of the cantilever beam 101.
• the method 600 comprises the step of applying 601 a first electrical field to the first piezoelectrical portion 102a and a second electrical field to the second piezoelectrical portion 102b such that, when applying the first electrical field to the first piezoelectrical portion 102a and the second electrical field to the second piezoelectrical portion 102b, the first electrical field forces the first piezoelectrical portion 102a to bend in a first lateral direction A and the second electrical field forces the second piezoelectrical portion 102b to bend in a second lateral direction B different from the first lateral direction A, thereby causing lateral movement of the second free end 101 b of the cantilever beam 101.
• the disclosed system, apparatus, and method may be implemented in other manners.
• the described embodiment of an apparatus is merely exemplary.
• the unit division is merely logical function division and may be another division in an actual implementation.
• a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not performed.
• the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented by using some interfaces.
• the indirect couplings or communication connections between the apparatuses or units may be implemented in electronic, mechanical, or other forms.
• the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.
• functional units in the embodiments of the invention may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Micromachines (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=70922051

Family Applications (1)

Country Status (2)

Family Cites Families (5)

• 2020
  • 2020-05-29 WO PCT/EP2020/064945 patent/WO2021239243A1/en unknown
  • 2020-05-29 EP EP20729722.7A patent/EP4158700A1/de active Pending

Also Published As

Similar Documents

Legal Events