SENSOR AND/OR TRANSDUCER DEVICE AND METHOD FOR OPERATING A SENSOR AND/OR TRANSDUCER DEVICE HAVING AT LEAST ONE BENDING STRUCTURE, WHICH INCLUDES AT LEAST ONE PIEZOELECTRIC LAYER
20170352795 · 2017-12-07
Inventors
Cpc classification
International classification
Abstract
A sensor and/or transducer device having at least one bending structure including at least one piezoelectric layer in each case, using which an intermediate volume between at least two electrodes of the bending structure is at least partially filled in each case, the sensor and/or transducer device including an electronic unit, which is designed to apply at least one predefined or established actuator voltage between two of the electrodes at a time of the bending structure in such a way that a deformation of the bending structure triggered by an intrinsic stress gradient in the bending structure may be at least partially compensated for. A method for operating a sensor and/or transducer device having at least one bending structure, which includes at least one piezoelectric layer, and a method for calibrating a microphone having at least one bending structure, which includes at least one piezoelectric layer, are also described.
Claims
1. A sensor and/or transducer device, comprising: at least one bending structure including at least one piezoelectric layer in each case, using which an intermediate volume between at least two electrodes of the bending structure is at least partially filled in each case, the bending structure having at least one self-supporting area which is adjustable in relation to an anchored area of the bending structure under at least one of a compression and an elongation of the at least one piezoelectric layer; and an electronic unit designed to apply at least one predefined or established actuator voltage between two of the electrodes at a time of the bending structure, in such a way that a deformation of the bending structure triggered by an intrinsic stress gradient in the bending structure is at least partially compensated for.
2. The sensor and/or transducer device as recited in claim 1, wherein the bending structure includes, as electrodes, at least one first outer electrode, at least one second outer electrode, and at least one intermediate electrode situated between the at least one first outer electrode and the at least one second outer electrode, and, as the at least one piezoelectric layer, a first piezoelectric layer is provided in a first intermediate volume between the at least one first outer electrode and the at least one intermediate electrode and a second piezoelectric layer is provided in a second intermediate volume between the at least one intermediate electrode and the at least one second outer electrode.
3. The sensor and/or transducer device as recited in claim 2, wherein the bending structure only includes, as the electrodes, the first outer electrode, the second outer electrode, and the intermediate electrode situated between the first outer electrode and the second outer electrode, and the electronic unit is designed to output at least one electrical output signal with respect to a sensing voltage applied between the first outer electrode and the intermediate electrode and to apply the predefined or established actuator voltage between the intermediate electrode and the second outer electrode.
4. The sensor and/or transducer device as recited in claim 2, wherein the bending structure includes a first sensing electrode and a first actuator electrode as the at least one first outer electrode, a second sensing electrode and a second actuator electrode as the at least one second outer electrode, and a third sensing electrode, which is located between the first sensing electrode and the second sensing electrode, and a third actuator electrode, which is located between the first actuator electrode and the second actuator electrode, as the at least one intermediate electrode, and the electronic unit is designed to output at least one electrical output signal with respect to at least one sensing voltage applied between two of the sensing electrodes at a time and to apply the at least one predefined or established actuator voltage between two of the actuator electrodes at a time.
5. The sensor and/or transducer device as recited in claim 1, wherein the sensor and/or transducer device has at least two bending structures, which each include the at least one piezoelectric layer, and the electronic unit is designed to apply different predefined or established actuator voltages between the electrodes of the at least two bending structures.
6. A microphone including a sensor and/or transducer device, the sensor and/or transducer including: at least one bending structure including at least one piezoelectric layer in each case, using which an intermediate volume between at least two electrodes of the bending structure is at least partially filled in each case, the bending structure having at least one self-supporting area which is adjustable in relation to an anchored area of the bending structure under at least one of a compression and an elongation of the at least one piezoelectric layer; and an electronic unit designed to apply at least one predefined or established actuator voltage between two of the electrodes at a time of the bending structure, in such a way that a deformation of the bending structure triggered by an intrinsic stress gradient in the bending structure is at least partially compensated for.
7. The microphone as recited in claim 6, wherein the electronic unit is designed to establish a minimum limiting value of a frequency range of sound waves which may be amplified with the aid of the microphone, in that the at least one predefined or established actuator voltage is applied between two of the electrodes of the bending structure at a time with the aid of the electronic unit in such a way that the deformation of the bending structure triggered by the intrinsic stress gradient in the bending structure is at least partially compensated for.
8. A method for operating a sensor and/or transducer device having at least one bending structure, which includes at least one piezoelectric layer, the method comprising: at least partially compensating for a deformation, which is triggered by an intrinsic stress gradient in the bending structure, of the bending structure having at least one self-supporting area, which is adjusted in relation to an anchored area of the bending structure under at least one of a compression and an elongation of the at least one piezoelectric layer, by applying at least one predefined or established actuator voltage between two of the electrodes at a time of the bending structure, whose intermediate volume is at least partially filled using the at least one piezoelectric layer.
9. The method as recited in claim 8, wherein different predefined or established actuator voltages are applied between the electrodes of the bending structures.
10. A method for calibrating a microphone having at least one bending structure, which includes at least one piezoelectric layer, the method comprising: setting a minimum limiting value of a frequency range of sound waves which may be amplified with the aid of the microphone, in that a deformation, which is triggered by an intrinsic stress gradient in the bending structure, of the bending structure having at least one self-supporting area, which is adjusted in relation to an anchored area of the bending structure under at least one of a compression and an elongation of the at least one piezoelectric layer, is one of at least partially compensated for or increased, by applying at least one predefined or established actuator voltage between two of the electrodes at a time of the bending structure, whose intermediate volume is at least partially filled using the at least one piezoelectric layer.
11. The method as recited in claim 10, wherein in calm surroundings, a first minimum limiting value of the frequency range of sound waves which may be amplified is set with the aid of at least one predefined or established first actuator voltage, and in windy surroundings, a second limiting value of the frequency range of sound waves which may be amplified, which is greater compared to the first minimum limiting value, is set with the aid of at least one predefined or established second actuator voltage.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Further features and advantages of the present invention are explained below on the basis of the figures.
[0017]
[0018]
[0019]
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0020]
[0021] The sensor and/or transducer device which is schematically shown with the aid of
[0022] The sensor and/or transducer device of
[0023] In the specific embodiment of
[0024] Electrodes 16 through 20 may (perpendicularly in relation to a direction from first outer electrode 16 to second outer electrode 18) have an extension a, which is significantly less than an extension A of the at least one piezoelectric layer 12 and 14 (perpendicularly in relation to a direction from first outer electrode 16 to second outer electrode 18). For example, an extension a of electrodes 16 through 20 is approximately one-third of extension A of piezoelectric layers 12 and 14. Notwithstanding the depiction in
[0025] Instead of the design of bending structure 10 having two piezoelectric layers 12 and 14, as shown in
[0026] Bending structure 10 has at least one self-supporting area 10a/at least one self-supporting end, which is adjustable under a compression and/or elongation of the at least one piezoelectric layer 12 and 14 in relation to an anchored area 10b/anchored end of bending structure 10. Bending structure 10 is therefore deformable with the aid of a force exerted thereon and/or a pressure exerted thereon, the at least one piezoelectric layer 12 and 14 being compressed and/or elongated. Since a variety of options are possible for fixing anchored area 10b/anchored end, this will not be discussed in greater detail here.
[0027] Before a release of the at least one self-supporting area 10a/self-supporting end of bending structure 10 (in general by removing a sacrificial layer material), bending structure 10 is provided in an initial position, which is shown with the aid of lines 22 in
[0028] The deformation of bending structure 10 triggered by the intrinsic stress gradient (in bending structure 10) may typically impair a sensitivity of the sensor and/or transducer device. In a sensor and/or transducer device used as a microphone, gap 24 frequently causes a variable “leak resistance,” which makes it impossible to amplify low sound frequencies.
[0029] However, the sensor and/or transducer device has a (schematically shown) electronic unit 28, which is designed to apply at least one actuator voltage Ua between two of electrodes 16 through 20 at a time of bending structure 10 in such a way that the deformation of bending structure 10 triggered by the intrinsic stress gradient may be at least partially compensated for (see
[0030] Typical effects of intermediate gap 24 on a sensitivity of bending structure 10/the sensor and/or transducer device equipped therewith therefore no longer have to be accepted due to the equipping of the sensor and/or transducer device with electronic unit 28. Equipping the sensor and/or transducer device with advantageously designed electronic unit 28 therefore contributes to improving the sensitivity of bending structure 10/the sensor and/or transducer device equipped therewith.
[0031]
[0032] The at least one actuator voltage Ua may be at least one (permanently) predefined actuator voltage Ua or at least one (newly) established actuator voltage Ua. For example, the at least one (permanently) predefined actuator voltage Ua may be stored unerasably on a (nonerasable) memory 28a. During a startup of the sensor and/or transducer device, memory 28a may be read out automatically and the at least one actuator voltage Ua may subsequently be applied accordingly. Alternatively, the sensor and/or transducer device may also be designed to (regularly) carry out a self-calibration to predetermine/newly predetermine the at least one actuator voltage Ua and possibly to buffer the at least one actuator voltage Ua subsequently on (erasable) memory 28a. Advantageous possibilities for establishing/reestablishing the at least one actuator voltage Ua are also described hereafter. The present invention therefore provides extremely sensitive sensor and/or transducer devices.
[0033] It is also to be noted that to manufacture the sensor and/or transducer device described here, only comparatively few requirements are to be maintained by the at least one deposition method carried out to form bending structure 10. Since the intrinsic stress gradient which results in bending structure 10 during the particular deposition method which is carried out, or the effects thereof on bending structure 10, may be easily compensated for, a variety of deposition methods which may be carried out simply and rapidly may be used (in particular to manufacture the at least one piezoelectric layer 12 and 14). In addition, it is not necessary to form at least one stabilizing intermediate layer on bending structure 10, to counteract an intrinsic stress gradient occurring in the at least one piezoelectric layer 12 and 14. This reduces the manufacturing costs of bending structure 10, or the sensor and/or transducer device equipped therewith.
[0034]
[0035] As is apparent in
[0036] Electronic unit 28 may also be designed in particular to establish a minimum limiting value of a frequency range of soundwave 34 which may be amplified (with the aid of the sensor and/or transducer device designed as a microphone), in that the at least one predefined or established actuator voltage Ua may be applied/is applied between two of electrodes 16 through 20 of bending structure 10 at a time with the aid of electronic unit 28, in such a way that the deformation of bending structure 10 triggered by the intrinsic stress gradient is at least partially compensated for or increased.
[0037]
[0038] In the specific embodiment of
[0039] In another alternative specific embodiment, electronic unit 28 may also be designed to use at least two of electrodes 16 through 20 both for applying the at least one predefined or established actuator voltage Ua and for simultaneously tapping the at least one sensing voltage Us. If desired, in this case a filter may be used for filtering out the at least one actuator voltage Ua (as a DC voltage signal) from the at least one sensing voltage Us (as an AC voltage signal).
[0040]
[0041] The sensor and/or transducer device which is schematically shown in
[0042] As is apparent on the basis of a comparison of
[0043] It is to be noted that the specific embodiment of
[0044] In general, an extension al of sensing electrodes 16 through 20 (perpendicular in relation to the direction from first outer electrode 16 to second outer electrode 18) is approximately one-third of extension A of piezoelectric layers 12 and 14 (perpendicular in relation to the direction from first outer electrode 16 to second outer electrode 18). Therefore, actuator electrodes 50 through 54 may be formed having a comparatively large extension a2 (perpendicular in relation to the direction from first outer electrode 16 to second outer electrode 18). Actuator electrodes 50 through 54 may be formed, for example, (almost) twice as large as sensing electrodes 16 through 20. Therefore, on the other hand, the deformation of bending structure 10 resulting from the intrinsic stress gradient may already be counteracted with the aid of at least one comparatively low actuator voltage Ua.
[0045] In another specific embodiment, the above-described techniques may also be combined with one another. An additional DC voltage signal may be applied to sensing electrodes 16 through 20, which are preferably located close to or directly on anchored area 10b, so that sensing electrodes 16 through 20 are also used for counteracting the intrinsic stress gradient. This combination has the additional advantage of further smoothing of bending structure 10. In addition, at least one additional sensing voltage may also be tapped at actuator electrodes 50 through 54.
[0046] The above-described specific embodiments may have, as a refinement, instead of single bending structure 10, at least two, in particular multiple bending structures 10, which in particular each include the at least one piezoelectric layer 12 and 14. In this case, electronic unit 28 is preferably designed to apply different predefined or established actuator voltages Ua between electrodes 16 through 20 and 50 through 54 of various bending structures 10.
[0047] As an additional refinement, each of the above-described sensor and/or transducer devices may also be designed for self-optimization, in that they measure their sound amplification during the operation and set it to an optimized value by adjusting the at least one bending structure 10. This also contributes to improving their functionality and to increasing their sensitivity.
[0048]
[0049] The method has at least one method step S1, in which a deformation of the bending structure triggered by an intrinsic stress gradient in the bending structure, by which at least one self-supporting area of the bending structure is adjusted in relation to an anchored area of the bending structure under a compression and/or elongation of the at least one piezoelectric layer, is at least partially compensated for. This is carried out by applying at least one predefined or established actuator voltage between two of the electrodes of the bending structure at a time, whose intermediate volume is at least partially filled using the at least one piezoelectric layer. At least two bending structures may possibly also be “bent” into a more optimized form in method step S1. For this purpose, different predefined or established actuator voltages may be applied between the electrodes of various bending structures.
[0050] Method step S1 may be carried out in particular to calibrate a sensor and/or transducer device which is designed as a microphone, having the at least one bending structure, which includes the at least one piezoelectric layer. A minimum limiting value of a frequency range which may be amplified (with the aid of the microphone/the particular bending structure) of sound waves is set, by applying the at least one predefined or established actuator voltage between two of the electrodes of the bending structure at a time (whose intermediate volume is at least partially filled using the at least one piezoelectric layer) to at least partially compensate for or increase the deformation of the bending structure triggered by the intrinsic stress gradient in the bending structure (due to which the at least one self-supporting area is adjusted in relation to the anchored area of the bending structure under a compression and/or elongation of the at least one piezoelectric layer).
[0051] Method step S1 may be carried out after a fabrication of the sensor and/or transducer device. Alternatively, at least method step S1 may also be regularly repeated to calibrate the sensor and/or transducer device. This makes it possible to reestablish the at least one actuator voltage based on calibration measurements or on surroundings conditions.
[0052] For example, windy surroundings may make amplification of certain low frequency sound signals impossible, since this would overload the amplifier. Under these conditions, it is advantageous if the minimum frequency limiting value is automatically increased in such a way that wind noises are already mechanically filtered out on the sensor side. In calm surroundings, the minimum limiting value may be established at the lowest possible value, in contrast, which significantly improves a signal quality. Method step S1 is therefore preferably carried out in such a way that in calm surroundings, a first minimum limiting value of the frequency range of sound waves which may be amplified is set with the aid of at least one predefined or established first actuator voltage, and in windy surroundings, a second limiting value, which is greater compared to the first minimum limiting value, of the frequency range of sound waves which may be amplified is set with the aid of at least one predefined or established second actuator voltage.
[0053] In one refinement, prior to method step S1, an optional method step S2 may also be carried out to establish the at least one actuator voltage. For example, at least one initial value for at least one lower limiting value of sound waves which may be amplified with the aid of the at least one bending structure may be measured, and subsequently the at least one actuator voltage may be established in consideration of the at least one measured initial value. Alternatively, other methods may also be applied for directly demonstrating the deformation of the at least one bending structure existing due to the at least one intrinsic stress gradient, in order to establish the at least one actuator voltage. For example, the deformation of the at least one bending structure may be measured with the aid of optical methods (in particular interferometry, for example). In all exemplary embodiments of method step S2 described here, the at least one actuator voltage may be established in consideration of the particular obtained information in such a way that the intrinsic stress gradient in the bending structure (and/or its consequences) is at least partially compensated for.
[0054] The at least one actuator voltage established in method step S2 may be stored on a nonerasable memory. If method step S2 is repeated multiple times for a self-calibration during operation of the sensor and/or transducer device, the at least one actuator voltage established in method step S2 may also be stored on a nonerasable memory. During a startup of the sensor and/or transducer device, the memory may be read out automatically and the at least one actuator voltage may subsequently be applied accordingly.