Z-axis accelerometer with increased sensitivity

Abstract

Z-axis rocker accelerometer featuring: a substrate; an anchor; a beam connected to the substrate by the anchor and configured to pivot about a first axis, the first axis being parallel to the substrate, the beam being asymmetrical relative to the first axis; and a proof mass coupled to the beam and configured to pivot about a second axis different from the first axis relative to the beam, the proof mass being coupled to the beam on one side and the second axis being parallel to the one side and fixed in a plane with the beam.

Description

Area of ​​Revelation

[0001] The present invention relates to microelectromechanical system (MEMS) z-axis accelerometers. background

[0002] A z-axis accelerometer may have a "seesaw" beam that pivots along the z-axis in response to acceleration. The beam's deflection amplitude may decrease at higher acceleration frequencies.

[0003] US 2012 0 125 103 A1 relates to a capacitive acceleration sensor for the Z-axis, comprising a substrate, a capacitive sensor plate, a proof mass, and at least one pair of cantilevers. The capacitive sensor plate comprises two symmetrical sensing regions for generating a differential capacitive measurement. A decoupling structure separates the proof mass and the capacitive sensor plate, as well as their rotational movements. In the proposed capacitive acceleration sensor for the Z-axis, the distance of the capacitive sensor plate relative to its rotational axis is significantly increased, effectively improving the sensitivity when measuring Z-axis acceleration.

[0004] DE 10 2013 212 915 A1 relates to a movable part that rotates about a rotation axis passing through a support when an inertial force is applied in a sensing direction to an inertial sensor. The movable part includes a first region and a second region that is displaced in a direction opposite to a direction of the first region when the inertial force is applied. A second substrate includes a first sensing electrode opposite the first region and a second sensing electrode opposite the second region. The first sensing electrode and the second sensing electrode are provided symmetrically with respect to the rotation axis. A cavity is provided symmetrically with respect to the rotation axis.In a direction perpendicular to the detection direction and a direction in which the rotation axis extends, a length from the rotation axis to one end of the first region and a length from the rotation axis to one end of the second region are different.

[0005] US 2003 0 036 214 A1 relates to an apparatus and a method for suspending a movable structure from a support structure, wherein first and second flat and thin arcuately shaped flexures are formed with spaced-apart, substantially planar and parallel opposing surfaces, wherein each of the first and second flexures is adapted to be connected between a support structure and a movable structure to be suspended from the support structure and to be aligned along a common axis of rotation between the support structure and the movable structure.

[0006] DE 11 2012 003 562 T5 relates to a detection structure for a z-axis resonant accelerometer comprising an inertial mass attached to a substrate by means of elastic anchoring elements so as to be suspended above the substrate, wherein the elastic elements are arranged to enable the inertial mass to perform an inertial rotational movement about a first axis of rotation parallel to a horizontal axis belonging to the plane of the main extension of the inertial mass in response to an external acceleration acting along a vertical axis transverse to a plane.A first resonator element and a second resonator element are mechanically coupled to the inertial mass by respective elastic support elements, wherein the elastic support elements are configured to enable a rotational movement of the first resonator element about a second rotation axis and of the second resonator element about a third rotation axis. The second rotation axis and the third rotation axis are aligned in particular parallel to each other and, furthermore, parallel to the first rotation axis of the inertial mass. Brief description of Revelation

[0007] A z-axis rocker accelerometer according to claim 1, a method of operating a z-axis accelerometer according to claim 11, and a z-axis accelerometer according to claim 15 are disclosed. Advantageous embodiments are recited in the subclaims. Short description of the drawings

[0008] Various aspects and embodiments of the application are described with reference to the following figures. It should be understood that the figures are not necessarily drawn to scale. Elements that appear in multiple figures are identified by the same reference numeral in all figures in which they appear. Fig. 1A is a side view of one embodiment of a z-axis accelerometer with a pivoting proof mass; Fig. 1B is a side view of one embodiment of a z-axis accelerometer with a pivoting proof mass; Fig. 1C is a plan view of one embodiment of a z-axis accelerometer with a pivoting proof mass; Fig. 2 is a plan view of one embodiment of a z-axis accelerometer with a pivoting proof mass; Fig. 3 is a plan view of one embodiment of a z-axis accelerometer with a pivoting proof mass; Fig. 4 is a plan view of an embodiment of a z-axis accelerometer with a pivoting proof mass; Fig. 5 is a plan view of one embodiment of a z-axis accelerometer with a pivoting proof mass; Fig. 6 is a plan view of an embodiment of a z-axis accelerometer with a pivoting proof mass; Fig. 7 is a plan view of an embodiment of a z-axis accelerometer with a pivoting proof mass; Fig. 8A is a side view of one embodiment of a z-axis accelerometer with a translating proof mass; Fig. 8B is a side view of one embodiment of a z-axis accelerometer with a translating proof mass; Fig. 8C is a plan view of one embodiment of a z-axis accelerometer with a translating proof mass; Fig. 9 illustrates a motor vehicle that may include a z-axis accelerometer of any of the types described herein, according to a non-limiting embodiment of the present application; and Fig. 10 illustrates an industrial equipment item having three z-axis accelerometers of the types described herein disposed thereon, in accordance with a non-limiting embodiment of the present application. Detailed description

[0009] Aspects of the present application relate to a MEMS z-axis accelerometer having a pivoting beam with a proof mass configured for movement relative to the beam. In various embodiments, the proof mass may be configured for pivoting out of a plane of the beam, for translating out of a plane of the beam, or, in some embodiments, for both pivoting and translating out of a plane of the beam. The proof mass coupled to the beam may be configured to move with a larger amplitude relative to the substrate than the beam in response to acceleration in the z-direction, at least for a target operating frequency of the accelerometer. Movement of the proof mass relative to the beam may result in increased sensitivity of the accelerometer compared to when no proof mass is present.In some embodiments, a frequency range in which increased sensitivity is achieved may include 2 kHz to 16 kHz. In various embodiments, an operating frequency may be 11.6 kHz, 12.1 kHz, or 13.7 kHz, although other frequencies are possible, and the various aspects described herein are not limited to these specific frequencies.

[0010] The inventors have further recognized that the sensitivity of a cantilevered beam (or "seesaw") type z-axis accelerometer can be increased by using a proof mass configured to move relative to a cantilever plane. A cantilevered z-axis accelerometer may include a substrate, at least one armature, and a beam coupled to the at least one armature and configured to pivot about a first axis parallel to the substrate. However, the deflection amplitude of the beam may decrease with increasing frequency of the acceleration applied to the accelerometer, for example, decreasing as the square of the frequency of the applied acceleration. Accordingly, the sensitivity of the accelerometer may decrease at higher operating frequencies and, accordingly, may at some point be too insensitive to be useful at certain higher frequencies.The inventors have identified a means for increasing the sensitivity of a MEMS z-axis rocker accelerometer, even at higher frequencies. In some embodiments, the means may be a proof mass coupled to the beam and configured to move relative to the beam. The proof mass coupled to the beam may have a different stiffness with respect to deflection due to acceleration in the z-direction than a stiffness of the beam with respect to deflection due to acceleration in the z-direction. Some embodiments may include two or more proof masses movable relative to the beam.

[0011] According to one aspect of the present application, the MEMS z-axis rocker accelerometer includes a beam configured to pivot about a first axis and a proof mass coupled to the beam and configured to pivot about a second axis, different from the first axis, relative to the beam. The beam may be supported or suspended above a substrate, and the first and second axes may be parallel to the substrate. The second axis may be parallel to the first axis in some embodiments or perpendicular to the first axis in other embodiments. In some embodiments, the second axis may be parallel to a plane of the beam.The pivoting motion of the proof mass relative to the beam can cause the accelerometer to demonstrate increased sensitivity compared to an accelerometer without the pivoting proof mass, because the proof mass can provide a larger deflection of the accelerometer in response to an input acceleration. Second axis.

[0012] According to one aspect of the present application, the seesaw accelerometer includes a beam configured to pivot about a first axis, a proof mass coupled to the beam, and configured to translate out of plane from the beam. That is, in some embodiments, the proof mass may be configured not to pivot about the first axis. The inventors have recognized that a proof mass coupled to the beam of a seesaw accelerometer and configured to translate out of plane relative to a pivot plane of the beam may increase the sensitivity of the accelerometer by providing a larger displacement in response to an input acceleration. In some embodiments, the out-of-plane displacement relative to the plane may be vertical.

[0013] Aspects of the present application may provide a beam formed in various arrangements. In some embodiments, the beam may include a first portion and a second portion. In some embodiments, the beam further includes a third portion. The first portion may be adjacent to the second portion, and the second portion may be located between the first portion and the third portion. The first portion and the second portion of the beam may be separated by the first axis. In embodiments where the beam includes a first portion and a second portion, the second portion may have a greater mass than the first portion of the beam. In embodiments where the beam includes first, second, and third portions, the second and third portions may have a greater combined mass than the first portion of the beam.

[0014] According to aspects of the present application, a proof mass can assume various positions relative to the beam. In various embodiments, the proof mass can be coupled to any of the first part of the beam, the second part of the beam, or the third part of the beam. In some embodiments, the proof mass is embedded in one or more parts of the beam. In some embodiments, the proof mass is partially or completely surrounded by the beam. In some embodiments, the proof mass may not be embedded in any part of the beam; for example, the proof mass may be coupled to an outer edge of the beam. In some embodiments, the beam may be disposed in a part distal to the first axis, which may increase the sensitivity of the accelerometer.

[0015] Aspects of the present application provide various orientations in which the proof mass may be coupled to the beam. In some embodiments, the proof mass has a first side proximate the first axis and a second side distal to the first axis. In some embodiments, the first side may be coupled to the beam, the second side may be coupled to the beam, or in some embodiments, both the first side and the second side of the proof mass may be coupled to the beam.

[0016] According to one aspect of the present application, the proof mass can be coupled to the beam through various structures. In some embodiments, the proof mass can be coupled to the beam through at least one spring or a support element. The at least one spring can be at least one torsion spring. The at least one spring can be at least one flexural spring. In some embodiments, the springs include both torsion and flexural springs.

[0017] According to aspects of the present application, an accelerometer includes structures other than the beam and proof mass. For example, sensing, drive, and / or self-test electrodes may be provided. In some embodiments, signal electrodes may be included, which may be drive and / or sense electrodes. In some embodiments, electrodes are provided on the substrate, such as signal electrodes. In some embodiments, electrodes are provided on the beam. Alternatively or additionally, the beam itself may form one or more electrodes. Electrodes may be formed by or disposed on any of the first, second, and third portions of the beam. Electrodes may be disposed on the substrate beneath one or more portions of the beam. In some embodiments, there are two or more electrodes, each associated with a different sensing region of the beam.

[0018] A sensing region may include a portion of the beam facing an electrode. A sensing region may include a portion of the beam including a proof mass, a portion of the beam without a proof mass, a proof mass, or other structures of the beam. In some embodiments, drive electrodes may be used to provide a drive signal to the beam. The drive signal may be provided to the beam by a first drive electrode and a second drive electrode, which may be disposed on the substrate beneath the beam. The drive signal may be a differential drive signal, at least in some embodiments.

[0019] The beam and / or the electrodes can sense the deflection of the beam relative to the substrate. The electrodes and the beam can form one or more sense capacitors, each providing a changing sense capacitance between the electrodes and the beam in response to movement of the beam. The one or more sense capacitors can provide a differential output or a pseudo-differential output. In some embodiments, a differential output can be provided by the beam. The output of the sense capacitors can be used to determine the acceleration of the accelerometer. The sense capacitors can provide a signal with higher sensitivity in an embodiment with a proof mass configured to move relative to the beam than in an embodiment without the proof mass.The proof mass may cause the signal from the sense capacitors to be not fully differential relative to each other.

[0020] Aspects of the present application may provide a beam configured to provide two or more substantially equal sensing regions of the beam. In some embodiments, there may be a first sensing region including a portion of the beam and a second sensing region including a proof mass. In these embodiments, it may be advantageous to configure the beam such that the first and second sensing regions are substantially equal.

[0021] According to aspects of the present application, the beam may include one or more structures to provide two or more substantially equal sensing areas of the beam. In some embodiments, the beam may include at least a first opening in the beam. The first opening may be adjacent to the proof mass. In some embodiments, the at least one spring may be adjacent to the at least one first opening in the beam. A portion of the beam beyond the first axis from the at least one spring may include at least one stub configured to occupy substantially the same area of ​​the beam as the at least one spring. The portion of the beam beyond the first axis from the at least one first opening may include at least one second opening configured to occupy substantially the same area of ​​the beam as the at least one first opening.The at least one spring, the at least one stub, the at least one opening, and the at least one second opening may be configured to provide two substantially equal sensing areas. In some embodiments, the first and second openings may provide stress relief for the beam.

[0022] The aspects and embodiments described above, as well as additional aspects and embodiments, are further described below. These aspects and / or embodiments may be used individually, all together, or in any combination of two or more, as the application is not limited in this regard.

[0023] Fig. Figure 1A is a schematic diagram illustrating a MEMS z-axis accelerometer according to an embodiment of the present application. The accelerometer 100 may be a rocker-type accelerometer, which may alternatively be referred to herein as a cantilever-type accelerometer. The accelerometer 100 may be configured to sense acceleration in the z-direction. The accelerometer 100 may include a beam 110, a proof mass 120, a substrate 130, and at least one armature 140.

[0024] In some embodiments, the beam 110 may move relative to the substrate 130 in response to an acceleration in the z-direction. Fig. 1A shows an illustration of an accelerometer 100 according to an embodiment of the present application when an acceleration of 0 g is applied in the z-direction. Fig. 1B shows an illustration of the accelerometer 100 according to an embodiment of the present application when an acceleration with a magnitude greater than 0 g is applied in the z-direction.

[0025] In some embodiments, the beam 100 can pivot about a first axis 192. The beam 110 can be arranged in a pivot plane. The first axis 192 can be aligned with an armature 140 such that the beam pivots about the armature. In some embodiments, the first axis 192 is in-plane with respect to the beam 110. In some embodiments, the first axis 192 is substantially parallel with respect to the substrate.

[0026] According to some aspects of the present application, the beam 110 may be configured in or include one or more parts. In some embodiments, the beam 110 may include a first part 112, a second part 114 adjacent to the first part, and a third part 116 adjacent to the second part. The parts may be substantially rectangular in some embodiments. The first part 112 may be separated from the second part 114 by the first axis 192 about which the beam pivots. In some embodiments, the first part 112 and the second part 114 may be separated by an axis other than the first axis 192. In some embodiments, the second part 114 may be separated from the third part 116 in a substantially similar manner.

[0027] The beam can be configured such that there is a mass imbalance between two sides of the beam 110 separated by the first axis 192. The second portion 114 and the third portion 116 can have a greater combined mass than the first portion 112, a smaller combined mass than the first portion, or in some embodiments, a substantially equal combined mass to the first portion. In an embodiment where the first portion 112 is separated from the second portion 114 by the first axis 192, the second portion 114 and the third portion 116 together can form part of the beam. In an embodiment where the second portion 114 and the third portion 116 have a greater combined mass than the first portion 112, the accelerometer 100 can be a seesaw accelerometer. In at least one aspect, the beam 110 can be asymmetric relative to an axis. The axis can be the first axis 192.In some embodiments, the beam 110 may be asymmetric with respect to its shape in the xy plane. In some embodiments, the beam 110 may be asymmetric with respect to its mass distribution. The beam 110 may further include openings or other structures arranged to form the mass of the beam and / or the mass of various portions of the beam. The mass of the first portion 112, the second portion 114, and the third portion 116 may be configured such that the beam 110 pivots in response to acceleration in the z-direction.

[0028] Aspects of the present application may also provide a proof mass 120. The proof mass 120 may be configured to increase the sensitivity of an accelerometer 100 to acceleration in the z-direction. In some embodiments, the proof mass 120 may move with respect to the beam 110. In some embodiments, the proof mass may move out of plane with respect to the beam 110. The proof mass may pivot and / or move relative to the beam. In the illustrative embodiment of Fig. 1B and Fig. 1C pivots the proof mass with respect to the beam about a second axis 194 that is substantially parallel to the first axis 192.

[0029] In some embodiments, the proof mass 120 may pivot about a second axis 194. The second axis 194 may be different from the first axis 192. The proof mass 120 may be configured to pivot about the second axis 194 in response to an acceleration in the z-direction. In the illustrative embodiment of Fig. 1C, the proof mass 120 can pivot about the second axis 194 substantially parallel to the first axis 192 and substantially parallel to the substrate 130. In the illustrative embodiment, the second axis 194 is spaced from the first axis 192 along a direction perpendicular to the first axis 192. The application is not limited in this regard, and the second axis 194 can be configured in any arrangement relative to the first axis 192. For example, the first axis 192 can be substantially perpendicular to the first axis 192 or can be arranged at an angle that is not substantially parallel or perpendicular relative to the first axis 192. The first axis 192 can be arranged in a plane of the beam 110 or can be arranged out of the plane of the beam.

[0030] In some embodiments, the proof mass may be arranged in various configurations relative to the beam. In the illustrative embodiment of Fig. 1C, the proof mass 120 is arranged in the second part 114 of the beam 110. The application is not limited in this respect, and the beam may be arranged in other configurations. For example, in some embodiments, the proof mass 120 is arranged in the first part 112 of the beam 110 or in the third part 116 of the beam. In some embodiments, the proof mass 120 may be at least partially embedded in one or more parts of the beam 110. In the illustrative embodiment of Fig. 1C, the proof mass 120 may be arranged such that it is embedded in the beam 110 in the second part 114. In some embodiments, the proof mass 120 may be partially or completely surrounded by the beam 110. In other embodiments, the proof mass 120 may be coupled to an outer edge of the beam 110 such that it is not embedded in the beam, such as in the illustrative embodiment of Fig. 4 is shown.

[0031] According to aspects of the present application, the proof mass 120 may be coupled to the beam in various orientations. The proof mass 120 may have a first side 122 and a second side 124. The first side 122 and the second side 124 may be arranged substantially parallel to the first axis 192. The application is not limited in this regard, and the first side 122 and the second side 124 may be arranged substantially perpendicular to the first axis 192 or may be arranged at an angle that is not substantially parallel or perpendicular relative to the first axis 192. The first side 122 may be proximate the first axis 192 and the second side 124 may be distal from the first axis 192. In the illustrative embodiment of Fig. 1C, the second side 124 of the proof mass 120 is coupled to the beam 110. The application is not limited in this regard, and any side of the proof mass 120 may be coupled to the beam 110. In the illustrative embodiment, the first side 122 of the proof mass 120 may be coupled to the beam 120. In other embodiments, any side of the proof mass 120 other than the first side 122 or the second side 124 may be coupled to the beam 110. For example, in an embodiment where the proof mass is substantially shaped as a rectangular prism, a side of the proof mass 120 that is substantially perpendicular to both the first side 122 and the second side 124 may be coupled to the beam 110.

[0032] The proof mass 120 may be coupled to the beam 110 by at least one spring of a suitable type, shape, dimension and orientation. Fig. 1C shows the proof mass 120 coupled to the beam 110 by springs 128. The springs may be arranged along a second axis 194 about which the proof mass 120 pivots with respect to the beam 110. In the illustrative embodiment of Fig. 1C, proof mass 120 is coupled to beam 110 by four torsion springs. The application is not limited with respect to the number of springs coupled between proof mass 120 and beam 110, and any number of springs may be used. A torsion spring may be any structure that allows pivoting about a pivot axis with some stiffness, although torsion springs of the present application are not limited in this regard. In some embodiments, beam 110 and / or proof mass 120 may be considered stiff and / or rigid relative to a torsion spring. In some embodiments, the proof mass is coupled to the beam by at least one flexure spring. A flexure spring may be any structure that allows displacement from a point with some stiffness, although the flexure springs of the present application are not limited in this regard.In some embodiments, the beam 110 and / or the proof mass 120 may be considered stiff and / or rigid relative to a flexural spring. The springs 128 may be formed from various lengths, cross-sectional areas, and material properties to achieve a desired torsional and / or flexural rigidity and / or stiffness.

[0033] Aspects of the present application may also provide a proof mass with various shapes. In the illustrative embodiment in Fig. 1C, the proof mass 120 is shaped substantially as a rectangular prism. However, the application is not limited in this respect, and the proof mass 120 may have a different shape, for example, a triangular prism or a cylinder, among other possibilities.

[0034] According to aspects of the present application, accelerometers may be provided that have two or more proof masses. If two or more proof masses are provided, they may be configured substantially similarly to proof mass 120, at least in one aspect. If two or more proof masses are provided, they may be arranged symmetrically with respect to the beam. For example, the two or more proof masses may be mirrored and / or shifted symmetrically across an axis substantially perpendicular to the first axis. In some embodiments, the two or more proof masses may be mirrored and / or shifted symmetrically across the first axis.

[0035] In some embodiments, the beam 110 may be arranged such that there is a substantially equal sensing area for each portion of the beam. The beam may include different components on a portion of the beam 110 distal from the proof mass 120 and a portion of the beam proximate the proof mass to form a substantially equal sensing area of ​​the parts.

[0036] The beam 110 may have at least one first opening 150. The first opening may be adjacent to the proof mass 120. The first opening 150 may be configured such that there is a gap between the proof mass 120 and the beam 110, which may allow the proof mass to move freely relative to the beam. In the illustrative embodiment of Fig. 1C, there is a first opening 150 adjacent to the proof mass 120 and the beam 110. The first opening 150 may surround the proof mass 120 and the first opening may be surrounded by the beam 110.

[0037] According to aspects of the present application, the first opening 150 may have one or more sides formed in various configurations. The first opening 150 may have a first side 152 and a second side 154. The first opening 150 may have one or more sides other than the first and second sides.

[0038] The sides of the first opening 150 can be arranged in different sizes. In the illustrative embodiment of Fig. 1C, the second side 154 of the first opening 150 is wider than the first side 152 of the first opening. In some embodiments, the first side 152 may be wider than the second side 154 or may be substantially equal in width to the second side.

[0039] The sides of the first opening 150 may be arranged at various angles relative to the beam. The first side 152 and the second side 154 may be arranged substantially parallel to the first axis 192. The application is not limited in this regard, and the first side 152 and the second side 154 may be arranged substantially perpendicular to the first axis 192 or may be arranged at an angle that is not substantially parallel or perpendicular relative to the first axis 192.

[0040] The sides of the first opening 150 can be arranged in various positions relative to the beam. In some embodiments, the first side 152 can be proximate the first axis 192, and the second side 154 can be distal from the first axis 192. In other embodiments, the first side 152 can be distal from the first axis 192, and the second side 154 can be proximate the first axis 192.

[0041] The first opening 150 may, in various embodiments, be arranged relative to the proof mass 120 and / or the springs 128. In some embodiments, a wider side of the first opening 150 may be a side adjacent to the side of the proof mass 120 that is coupled to the beam 110. In some embodiments, a wider side of the first opening 150 may be adjacent to a side of the proof mass 120 where a spring is arranged. In some embodiments, a spring 128 may be arranged on a wider side of the first opening 150. In the illustrative embodiment of Fig. 1C, the second side 154 is wider than the first side, and the second side is adjacent to the second side 124 of the proof mass 120. In the embodiment shown, the second side 124 is coupled to the beam 110 by the torsion springs 128, and the springs 128 are disposed on the second side 154 of the first opening.

[0042] In some embodiments, one or more structures may be disposed on a portion of the beam 110 beyond the first axis 192 from the proof mass 120. Structures may be disposed such that each of the plurality of electrodes associated with the beam is coupled to a substantially equal sensing area. In an embodiment where the accelerometer has two electrodes, the structures may be configured such that two portions of the beam 110 have a substantially equal sensing area. In the illustrative embodiment of Fig. 1C, the proof mass 120 and the first opening 150 are disposed in the second portion 114 of the beam. In the illustrative embodiment, there is a second opening 160 disposed in the first portion 112 of the beam 110, which is located beyond the first axis 192 from the first opening.

[0043] In some embodiments, the beam 110 may include at least one second opening 160. The second opening 160 may be arranged such that, at the same distance from the first axis 192 or another axis in two parts of the beam 110, there is substantially the same sensing area of ​​the beam.

[0044] According to aspects of the present application, the second opening 160 may have one or more sides formed in various configurations. The second opening 160 may have a first side 162 and a second side 164. The second opening 160 may have one or more sides other than the first and second sides.

[0045] The sides of the second opening 160 can be arranged in different sizes. In the illustrative embodiment, the second side 164 of the first opening 160 is wider than the first side 162 of the first opening. In some embodiments, the first side 162 can be wider than the second side 164 or can be substantially equal in width to the second side.

[0046] The sides of the second opening 160 may be arranged at different angles relative to the beam. The first side 162 and the second side 164 may be arranged substantially parallel to the first axis 192. The application is not limited in this regard, and the first side 162 and the second side 164 may be arranged substantially perpendicular to the first axis 192 or may be arranged at an angle that is not substantially parallel or perpendicular relative to the first axis 192.

[0047] The sides of the second opening 160 can be arranged in various positions relative to the beam. In some embodiments, the first side 162 can be proximate the first axis 192, and the second side 164 can be distal from the first axis 192. In other embodiments, the first side 162 can be distal from the first axis 192, and the second side 164 can be proximate the first axis 192.

[0048] The second opening 160 and the first opening 150 may be at least partially symmetrical in at least one respect. The second opening 160 and the first opening 150 may be at least partially symmetrical in that they may be at least partially mirrored and / or translated beyond the first axis 192. The first side 152 of the first opening and the first side 162 of the second opening may be equidistant from the first axis 192 and / or have substantially the same width. The second side 154 of the first opening 150 and the second side 164 of the second opening 160 may be equidistant from the first axis 192 and / or have substantially the same width. The first opening 150 and the second opening 160 may occupy substantially the same area in the xy plane.

[0049] The second opening 160 may include at least one stub 168. The stubs 168 may be arranged across the opening 160 and may be located on the first side 162, the second side 164, or another side. A portion of the stubs 168 located on a wider side of the second opening 160 may be configured such that the springs 128 and the portion of the stubs occupy a substantially equal area in the xy plane. In some embodiments, the stubs 168 may provide structural support for the beam 110.

[0050] Although Fig. 1C shows stubs disposed only on the second side 164 of the opening 160, it is understood that aspects of the present application are not limited in this respect. Stubs may be disposed on any side, such as sides between the first side and the second side, or on the first side, as shown in Fig. 8C (discussed below). The stubs may be arranged on all or most sides of a second opening. According to aspects of the present application, the stubs may be formed to be rigid enough, or formed in sufficient number, that a portion of a beam surrounded by a second opening does not move significantly with respect to the beam, even if stubs are located only on a single side of the opening, as in Fig. 1C.

[0051] The accelerometer 100 according to the present application may include a substrate 130. In the illustrative embodiment of Fig. 1A and Fig. 1B, the substrate 130 is arranged in the xy plane. The beam may be connected to the substrate by an anchor, and the beam may be arranged above the substrate. The beam may be supported above the substrate or suspended above it. In some embodiments, suspension or support of the beam may be achieved by various structures arranged on the substrate.

[0052] In some embodiments, the substrate 130 may have other structures. In some embodiments, the substrate 130 may have one or more sense electrodes, drive electrodes, and / or self-test electrodes. In the illustrative embodiment of Fig. 1A and Fig. 1B, the accelerometer includes a first electrode 132, a second electrode 134, and a self-test electrode 136. The first and second electrodes 132 and 134 may include drive and / or sense electrodes. In the illustrative embodiment, the electrodes are disposed on the substrate 130. In the illustrated embodiment, each electrode is coupled to a portion of the beam 110. However, the present application is not limited in this regard, and electrodes may be formed in other arrangements, for example, on the beam 110 or disposed on another substrate.

[0053] The first electrode 132 and the second electrode 134 may be configured to operate differently in different embodiments. In some embodiments, the first electrode 132 and the second electrode 134 may provide a drive signal, and the beam 110 and / or the proof mass 120 may be configured to provide a sense signal derived from the deflection of the beam 110 and / or the proof mass 120 relative to the substrate. In some embodiments, the electrodes 132 and 134 may be configured to provide a sense signal indicative of the deflection of the beam 110 and / or the proof mass 120 relative to the substrate.

[0054] The accelerometer 100 may include sensing capacitors. In some embodiments, the beam 110 may form sensing capacitors with both the first electrode 132 and the second electrode 134. In the illustrated embodiment of Fig. 1A and Fig. 1B, a first electrode 132 faces the first portion 112 of the beam 110 as a first sensing portion and forms a first sensing capacitor. A second electrode 134 faces the proof mass 120 and the second portion 114 of the beam 110 as a second sensing portion and forms a second sensing capacitor. The application is not limited in this respect, and each electrode may be arranged facing any portion or portions of the beam 110 and / or may be arranged facing the proof mass 120 in any arrangement of the proof mass to form different sensing capacitors. The sensing portions of the beam may be configured to form a substantially equal sensing area facing the electrodes, as described in accordance with the present application.

[0055] The capacitance of sense capacitors can be used to measure acceleration of beam 110. The capacitance of the first sense capacitor can vary with variation in the distance between beam 110 and substrate 130. The capacitance of the second sense capacitor can vary with variation in the distance between proof mass 120 and substrate 130. The capacitance of the sense capacitors can vary in response to deflection of beam 110. A signal derived from the deflection of beam 110 can be used to find the acceleration of the accelerometer in the z-direction.

[0056] The sense capacitors may provide an output signal indicative of a change in capacitance due to pivoting of the beam and / or movement of the proof mass. In some embodiments, the beam may provide a signal that may be used to indicate acceleration of the accelerometer. The first and second sense capacitors may provide a differential signal. The first sense capacitor may provide a first capacitance, and the second sense capacitor may provide a second capacitance. The first capacitance and the second capacitance may provide and / or be compared to a differential or pseudo-differential signal. That is, as one capacitance increases, the other capacitance may decrease.The second sense capacitor may provide a second capacitance having a higher amplitude relative to an embodiment in which no proof mass is configured to move relative to the beam 120. The second sense capacitor may provide a second capacitance having a higher amplitude than the first capacitance of the first sense capacitor. In at least this respect, capacitances of the first sense capacitor and the second sense capacitor may not be sufficiently differential relative to each other. That is, an increase in one signal may not correspond to a substantially equal decrease in the other signal, and vice versa. Sense capacitors coupled to portions of the beam located farther from the first axis 192 may provide signals with larger magnitudes.The capacitances of the first and second sensing capacitors can be used to determine an acceleration in the z-direction of the accelerometer 100.

[0057] Beam 110 may provide a differential or pseudo-differential output signal. In some embodiments, beam 110 forms an electrode, which includes any portion of the beam facing drive electrodes on the substrate. The beam's armature 140 may be electrically coupled to the beam. Armature 140 may be electrically coupled to a conductive trace or other structure disposed on substrate 130. Armature 140 may provide an output signal from beam 110 to the conductive trace.

[0058] In some embodiments, beam 110 forms an electrode coupled to the first sense capacitor and the second sense capacitor. Armature 140 may be disposed in a portion of the beam along the x-direction between the first sense capacitor and the second sense capacitor. Armature 140 may provide a differential signal indicative of the first and second capacitances provided by the first and second sense capacitors, respectively. The signal may be an output signal indicative of a comparison of the first and second capacitances. Armature 140 may provide the output signal to the conductive trace disposed on substrate 130. The conductive trace may provide the signal to a device disposed on the substrate or to a device external to the substrate.The device may comprise a circuit arrangement configured to process the output signal to determine an acceleration.

[0059] A self-test electrode 136 may be arranged facing a portion of the beam 110 that the electrodes 132 and 134 do not face. In the illustrative embodiment of Fig. 1A and Fig. 1B, the self-test electrode 136 faces the third portion 116 of the beam 120. The self-test electrode may face any appropriate portion of the beam. The self-test electrode 136 may be used to perform a self-test function of the z-axis accelerometer, but may optionally be omitted.

[0060] The accelerometer 100 according to the present application may also include at least one armature 140. In the illustrative embodiment of Fig. 1C, an armature 140 is provided. The application is not limited in this regard, and there may be any suitable number of armatures. For example, in some embodiments, there may be two or more armatures, which may be arranged in a line along the first axis 192. The armature 140 may be coupled to the substrate 130. The armature 140 may be arranged such that the beam 110 pivots about a first axis 192 that is substantially parallel to the substrate. At least one armature 140 may be arranged along the first axis 192 such that the beam 110 pivots about the armature. In the illustrative embodiment of Fig. 1C, the beam surrounds the anchor 140. The application is not limited in this regard, and the anchor 140 may be disposed at any location relative to the beam 110. For example, in the case of two or more anchors, the anchors may be disposed at outer edges of the beam 110. In such an embodiment, the anchors may be disposed along the first axis 192 or may not be disposed along the first axis 192. The anchors 140 may be substantially centered relative to the edges of the beam 110 in a direction substantially perpendicular to the first axis 192 or may be substantially off-centered relative to the edges of the beam in a direction substantially perpendicular to the first axis 192.

[0061] The armature 140 may be coupled to the beam 110 by at least one spring of a suitable type, shape, dimension, and orientation. In the illustrative embodiment of Fig. 1C, the armature 140 is coupled to the beam 110 by two springs 142. In the illustrative embodiment of Fig. 1C, the springs 142 are torsion springs. In some embodiments, the springs 142 may be torsion and / or bending springs. The beam 110 and / or the armature 140 may be considered stiff and / or rigid relative to the springs 142. The springs 142 may be formed from various lengths, cross-sectional areas, and material properties to achieve a desired torsional and / or bending rigidity and / or stiffness.

[0062] In some embodiments, beam 110, proof mass 120, substrate 130, at least one armature 140, and other components may be formed from a conductive and / or semiconductor material, such as polysilicon, silicon, or a metal conductor. If a semiconductor material is used, the material may be appropriately doped to exhibit a desired conductivity. The components may be formed using any suitable manufacturing process.

[0063] According to aspects of the present application, an electronic system may include an accelerometer as described above. The electrodes of an accelerometer according to the present application may be electrically coupled to a circuit board. The circuit board may be electrically coupled to other electronic components. In some embodiments, the accelerometer may be coupled to various external components. For example, the accelerometer may be electrically coupled to a power supply. In some embodiments, the accelerometer may be electrically coupled to a processor that processes signals from the accelerometer. The circuit board may be a printed circuit board.The electronic system can be used to detect accelerations in various situations, including, but not limited to, sports, healthcare, military, and industrial applications. Such non-limiting examples include sensing environments such as an automobile or other vehicle, industrial equipment (e.g., industrial machine health monitoring), or wearables such as personal health monitoring devices or fitness trackers.

[0064] Such an accelerometer, as described above, may provide a desirable method of operation for sensing acceleration in the z-direction. The accelerometer may include a substrate, at least one armature, a beam connected to the substrate by the at least one armature, and a proof mass configured to move relative to the beam. The beam may pivot about a first axis. The beam may be asymmetric relative to the first axis. The proof mass may be configured to move out of the plane of the beam. The proof mass may be configured to pivot and / or move relative to the beam. The proof mass may be configured to pivot about a second axis other than the first axis. The accelerometer may further include a first electrode and a second electrode, each disposed on the substrate.

[0065] The method according to some embodiments includes sensing an indication of a position of the beam relative to the substrate through at least one sensing capacitance and outputting a signal indicative of the at least one sensing capacitance. A drive AC signal may be applied to the beam through the electrodes. The output signal may be a differential signal based on a capacitance that varies with pivoting of the beam.

[0066] The method may further comprise performing at least one operation on the first output signal and / or the second output signal to calculate an acceleration applied to the accelerometer in the z-direction. For example, a suitable algorithm may be employed in logic or a processor to calculate an acceleration.

[0067] Various aspects and embodiments have been described with reference to the foregoing. However, alternatives may be implemented within the scope of the present application. First alternative embodiment

[0068] An alternative embodiment of a z-axis accelerometer can be described with reference to Fig. 2. The accelerometer 200 may include a beam 210, a proof mass 220, a substrate, and at least one armature 240. The accelerometer 200 may include a proof mass 220 coupled to the beam 210 by a first side 222 of the proof mass that is proximate a first axis about which the beam pivots.

[0069] In at least one aspect, the beam 210 may be configured substantially similar to the beam 110. The beam 210 may be configured to pivot about a first axis 292. In at least one aspect, the first axis 292 may be configured substantially similar to the first axis 192. The beam 210 may include a first portion 212, a second portion 214, and a third portion 216. In at least one aspect, the first portion 212 may be configured substantially similar to the first portion 112. In at least one aspect, the second portion 214 may be configured substantially similar to the second portion 114. In at least one aspect, the third portion 216 may be configured substantially similar to the third portion 116.

[0070] In at least one aspect, proof mass 220 may be configured substantially similar to proof mass 120. Proof mass 220 may be configured to pivot about a second axis 294. In at least one aspect, second axis 294 may be configured substantially similar to second axis 194. Proof mass 220 may have a first side 222 and a second side 224. In at least one aspect, first side 222 may be configured substantially similar to first side 122. In at least one aspect, second side 224 may be configured substantially similar to second side 124. Proof mass 220 may be coupled to beam 210 by at least one spring 228 and may be adjacent to at least one first opening 250. In at least one aspect, spring 228 may be configured substantially similar to spring 128. In the illustrative embodiment of Fig. 2, the first side 222 of the test mass 220 is coupled to the beam 210 by the springs 228.

[0071] In at least one aspect, the first opening 250 may be configured substantially similarly to the first opening 150. The first opening 250 may have a first side 252 and a second side 254. The first side 252 may be configured substantially similarly to the first side 152. The second side 254 may be configured substantially similarly to the second side 154. In the illustrative embodiment of Fig. 2, the first side 252 of the first opening 250 is wider than the second side 254 of the first opening.

[0072] The beam 210 may have a second opening 260 with a first side 262 and a second side 264 and may have a stub 268. The second opening 260 may be configured substantially similar to the second opening 160. The first side 262 may be configured substantially similar to the first side 162. The second side 264 may be configured substantially similar to the second side 164. The stub 268 may be configured substantially similar to the stub 168. In the illustrative embodiment of Fig. 2, the first side 262 of the second opening 260 is wider than the second side 264 of the second opening.

[0073] In at least one aspect, the substrate may be configured substantially similar to substrate 130. The substrate may include a first electrode, a second electrode, and a self-test electrode. In at least one aspect, the first electrode may be configured substantially similar to first electrode 132. In at least one aspect, the second electrode may be configured substantially similar to second electrode 134. In at least one aspect, the self-test electrode may be configured substantially similar to self-test electrode 136.

[0074] In the illustrative embodiment of Fig. 2, the accelerometer 200 includes an armature 240. In at least one aspect, the armature 240 may be configured substantially similarly to the armature 140. The armature 240 may be coupled to the beam 210 by a spring 242. In at least one aspect, the spring 242 may be configured substantially similarly to the spring 142. Second alternative embodiment

[0075] An alternative embodiment of a z-axis accelerometer can be described with reference to Fig. 3. The accelerometer 300 may include a beam 310, a proof mass 320, a substrate, and at least one armature 340. The accelerometer 300 may include a proof mass 320 coupled to a portion of the beam 310 that is not adjacent to a first axis about which the beam pivots. Such an embodiment may provide further increased sensitivity of the accelerometer to acceleration in the z-direction. The second portion 314 of the beam 310 is located between the first axis 392 and the proof mass 320, which may result in the proof mass being located a greater distance from the first axis. In various embodiments, the proof mass may be located at different distances from the first axis 392.

[0076] In at least one aspect, the beam 310 may be configured substantially similar to the beam 110. The beam 310 may be configured to pivot about a first axis 392. In at least one aspect, the first axis 392 may be configured substantially similar to the first axis 192. The beam 310 may include a first portion 312, a second portion 314, and a third portion 316. In at least one aspect, the first portion 312 may be configured substantially similar to the first portion 112. In at least one aspect, the second portion 314 may be configured substantially similar to the second portion 114. In at least one aspect, the third portion 316 may be configured substantially similar to the third portion 116.

[0077] In at least one aspect, proof mass 320 may be configured substantially similar to proof mass 120. Proof mass 320 may be configured to pivot about a second axis 394. In at least one aspect, second axis 394 may be configured substantially similar to second axis 194. Proof mass 320 may have a first side 322 and a second side 324. In at least one aspect, first side 322 may be configured substantially similar to first side 122. In at least one aspect, second side 324 may be configured substantially similar to second side 124. Proof mass 320 may be coupled to beam 310 by at least one spring 328 and may be adjacent to at least one first opening 350. In at least one aspect, spring 328 may be configured substantially similar to spring 128. In the illustrative embodiment of Fig. 3, the proof mass 320 is disposed in the third portion 316 of the beam 310. In the illustrative embodiment, the first side 322 of the proof mass 320 is coupled to the beam 310 by the springs 328. The application is not limited in this regard, and in some embodiments, other sides of the proof mass 320, for example, the second side 324 of the proof mass, may be coupled to the beam 310 by the springs 328.

[0078] In at least one aspect, the first opening 350 may be configured substantially similarly to the first opening 150. The first opening 350 may have a first side 352 and a second side 354. The first side 352 may be configured substantially similarly to the first side 152. The second side 354 may be configured substantially similarly to the second side 154. In the illustrative embodiment of Fig. 3, the first side 352 of the first opening 350 is wider than the second side 354 of the first opening.

[0079] The beam 310 may have a second opening 360 with a first side 362 and a second side 364 and may have a stub 368. The second opening 360 may be configured substantially similar to the second opening 160. The first side 362 may be configured substantially similar to the first side 162. The second side 364 may be configured substantially similar to the second side 164. The stub 368 may be configured substantially similar to the stub 168. In the illustrative embodiment of Fig. 3, the first side 362 of the second opening 360 is wider than the second side 364 of the second opening.

[0080] In at least one aspect, the substrate may be configured substantially similar to substrate 130. The substrate may include a first electrode, a second electrode, and a self-test electrode. In at least one aspect, the first electrode may be configured substantially similar to first electrode 132. In at least one aspect, the second electrode may be configured substantially similar to second electrode 134. In at least one aspect, the self-test electrode may be configured substantially similar to self-test electrode 136. In the illustrative embodiment of Fig. 3, the second electrode faces the proof mass 320 arranged in the third part 316 of the beam 310, and the self-test electrode faces the second part 314 of the beam.

[0081] In the illustrative embodiment of Fig. 3, the accelerometer 300 includes an armature 340. In at least one aspect, the armature 340 may be configured substantially similarly to the armature 140. The armature 340 may be coupled to the beam 310 by a spring 342. In at least one aspect, the spring 342 may be configured substantially similarly to the spring 142. Third alternative embodiment

[0082] An alternative embodiment of a z-axis accelerometer can be described with reference to Fig. 4. The illustrative accelerometer 400 in Fig. 4 may include a beam 410, a proof mass 420, a substrate, and at least one armature 440. The accelerometer 400 may include a proof mass 420 coupled to an outer edge of the beam 410.

[0083] In at least one aspect, the beam 410 may be configured substantially similar to the beam 110. The beam may be configured to pivot about a first axis 492. In at least one aspect, the first axis 492 may be configured substantially similar to the first axis 192. The beam 410 may include a first portion 412, a second portion 414, and a third portion 416. In at least one aspect, the first portion 412 may be configured substantially similar to the first portion 112. In at least one aspect, the second portion 414 may be configured substantially similar to the second portion 114. In at least one aspect, the third portion 416 may be configured substantially similar to the third portion 116.

[0084] In at least one aspect, proof mass 420 may be configured substantially similar to proof mass 120. Proof mass 420 may be configured to pivot about a second axis 494. In at least one aspect, second axis 494 may be configured substantially similar to second axis 194. Proof mass 420 may have a first side 422 and a second side 424. In at least one aspect, first side 422 may be configured substantially similar to first side 122. In at least one aspect, second side 424 may be configured substantially similar to second side 124. Proof mass 420 may be coupled to beam 410 by at least one spring 428 and may be adjacent to at least one first opening 450. In at least one aspect, spring 428 may be configured substantially similar to spring 128. In the illustrative embodiment of Fig. 4, the proof mass 420 is disposed in the third portion 416 of the beam 410. In the illustrative embodiment, the proof mass is coupled to an outer edge of the beam 410 by springs 428 and is not surrounded by the beam.

[0085] In at least one aspect, the first opening 450 may be configured substantially similarly to the first opening 150. The beam 410 may include a second opening 460 and may include a stub 468. The second opening 460 may be configured substantially similarly to the second opening 160. The stub 468 may be configured substantially similarly to the stub 168.

[0086] In at least one aspect, the substrate may be configured substantially similar to substrate 130. The substrate may include a first electrode, a second electrode, and a self-test electrode. In at least one aspect, the first electrode may be configured substantially similar to first electrode 132. In at least one aspect, the second electrode may be configured substantially similar to second electrode 134. In at least one aspect, the self-test electrode may be configured substantially similar to self-test electrode 136. In the illustrative embodiment of Fig. 4, the second electrode faces the proof mass 420 arranged in the third part 416 of the beam 410, and the self-test electrode faces the second part 414 of the beam.

[0087] In the illustrative embodiment of Fig. 4, the accelerometer 400 includes an armature 440. In at least one aspect, the armature 440 may be configured substantially similarly to the armature 140. The armature 440 may be coupled to the beam 410 by a spring 442. In at least one aspect, the spring 442 may be configured substantially similarly to the spring 142. Fourth alternative embodiment

[0088] An alternative embodiment of a z-axis accelerometer can be described with reference to Fig. 5. The accelerometer 500 may include a beam 510, a proof mass 520, a substrate, and at least one armature 540. The accelerometer may include a beam 510 centered relative to the armature 540. The beam 510 may have openings formed to reduce the mass of the beam on one side of a first axis about which the beam pivots.

[0089] Aspects of the present application provide at least one armature that is centered relative to the beam in a direction perpendicular to the first axis. In some embodiments, there may be a third opening in the first part of the beam configured such that the second part of the beam has a greater mass than the first part. In the embodiment, the proof mass may be coupled to either the first part or the second part of the beam. An embodiment with a centered armature may provide a displacement closer to zero when there is no acceleration in the z-direction, but may provide less sensitivity to acceleration in the z-direction compared to an embodiment where the armature is not centered.

[0090] In at least one aspect, the beam 510 may be configured substantially similar to the beam 110. The beam 510 may be configured to pivot about a first axis 592. In at least one aspect, the first axis 592 may be configured substantially similar to the first axis 192. In the illustrative embodiment of Fig. 5, the edges of the beam 510 distal from the first axis 592 are substantially centered relative to the first axis in a direction substantially perpendicular to the first axis. The beam 510 may extend substantially an equal distance from the first axis 592 in each of two directions that are substantially perpendicular to the first axis and lie in the plane of the beam.

[0091] The beam 510 may include a first portion 512, a second portion 514, and a third portion 516. In at least one aspect, the first portion 512 may be configured substantially similarly to the first portion 112. In at least one aspect, the second portion 514 may be configured substantially similarly to the second portion 114. The second portion 514 may be bisected by the first axis 592 into a lower portion adjacent the second gap 560 and a lower portion adjacent the first gap 550. In at least one aspect, the third portion 516 may be configured substantially similarly to the third portion 116.

[0092] The beam may include one or more structures configured to form the mass of the beam 510 on one side of the first axis 592. These structures may form the beam 510 such that the mass on one side of the first axis 592 is greater than the mass on the other side of the first axis.

[0093] The beam 510 may have openings that reduce the mass of the beam on one side of the first axis 592. In the illustrative embodiment of Fig. 5, the second portion of the beam is intersected by the first axis 592. In the illustrative embodiment, the beam 510 includes third openings 570 in the second portion of the beam on a side of the second portion 514 distal from the proof mass. However, the application is not limited in this regard, and in some embodiments, the beam 510 includes third openings 570 in the second portion of the beam on a side of the second portion proximate the proof mass 520, or in some embodiments, openings 570 in other portions of the beam. The third openings 570 may be configured to reduce the mass of the beam 510 on one side of a first axis 592. In some embodiments, the beam 510 may include structures configured to increase the mass of the beam on one side of the first axis 592.Other accelerometers according to the present application may include structures configured to increase and / or decrease the mass of a beam on one side of a first axis about which the beam pivots.

[0094] In at least one aspect, proof mass 520 may be configured substantially similar to proof mass 120. Proof mass 520 may be configured to pivot about a second axis 594. In at least one aspect, second axis 594 may be configured substantially similar to second axis 194. Proof mass 520 may have a first side 522 and a second side 524. In at least one aspect, first side 522 may be configured substantially similar to first side 122. In at least one aspect, second side 524 may be configured substantially similar to second side 124. Proof mass 520 may be coupled to beam 510 by at least one spring 528 and may be adjacent to at least one first opening 550. In at least one aspect, spring 528 may be configured substantially similar to spring 128. In the illustrative embodiment of Fig. 5, the proof mass 520 is disposed in the third portion 516 of the beam 510. In the illustrative embodiment, the first side 522 of the proof mass 520 is coupled to the beam 510 by the springs 528. However, the application is not limited in this regard, and other sides of the proof mass 520 may be coupled to the beam; for example, the second side 524 of the proof mass may be coupled to the beam 510.

[0095] In at least one aspect, the first opening 550 may be configured substantially similarly to the first opening 150. The first opening 550 may have a first side 552 and a second side 554. The first side 552 may be configured substantially similarly to the first side 152. The second side 554 may be configured substantially similarly to the second side 154. In the illustrative embodiment of Fig. 5, the first side 552 of the first opening 550 is wider than the second side 554 of the first opening.

[0096] The beam 510 may include a second opening 560 having a first side 562 and a second side 564, and may include a stub 568. The second opening 560 may be configured substantially similar to the second opening 160. The first side 562 may be configured substantially similar to the first side 162. The second side 564 may be configured substantially similar to the second side 164. The stub 568 may be configured substantially similar to the stub 168. In the illustrative embodiment, the first side 562 of the second opening 560 is wider than the second side 564 of the second opening.

[0097] In at least one aspect, the substrate may be configured substantially similar to substrate 130. The substrate may include a first electrode, a second electrode, and a self-test electrode. In at least one aspect, the first electrode may be configured substantially similar to first electrode 132. In at least one aspect, the second electrode may be configured substantially similar to second electrode 134. In at least one aspect, the self-test electrode may be configured substantially similar to self-test electrode 136. In the illustrative embodiment of Fig. 5, the second electrode faces the proof mass 520 disposed in the third portion 516 of the beam 510, and the self-test electrode faces the second portion 514 of the beam.

[0098] In the illustrative embodiment of Fig. 5, the accelerometer 500 includes an armature 540. In at least one aspect, the armature 540 may be configured substantially similar to the armature 140. The armature 540 may be coupled to the beam 510 by a spring 542. In at least one aspect, the spring 542 may be configured substantially similar to the spring 142. In the illustrative embodiment of Fig. 5, the armature 540 is substantially centered in the x-direction with respect to the outer edges of the beam 510. The first axis 592 is substantially centered in the x-direction with respect to the outer edges of the beam 510. The accelerometer 500 may include two or more armatures 540, each of which may be arranged along the first axis 592 and / or centered in the x-direction with respect to the outer edges of the beam 510. Fifth alternative embodiment

[0099] An alternative embodiment of a z-axis accelerometer can be described with reference to Fig. 6. The illustrative accelerometer 600 in Fig. 6 may include a beam 610, a proof mass 620, a substrate, and at least one armature 640. The accelerometer 600 may include a proof mass 620 pivoting about an axis formed at an angle other than parallel to the axis about which the beam 610 pivots.

[0100] In at least one aspect, the beam 610 may be configured substantially similar to the beam 110. The beam 610 may be configured to pivot about a first axis 692. In at least one aspect, the first axis 692 may be configured substantially similar to the first axis 192. The beam 610 may include a first portion 612, a second portion 614, and a third portion 616. In at least one aspect, the first portion 612 may be configured substantially similar to the first portion 112. In at least one aspect, the second portion 614 may be configured substantially similar to the second portion 114. In at least one aspect, the third portion 616 may be configured substantially similar to the third portion 116.

[0101] In at least one aspect, proof mass 620 may be configured substantially similar to proof mass 120. Proof mass 620 may be configured to pivot about a second axis 694. In at least one aspect, second axis 694 may be configured substantially similar to second axis 194. Proof mass 620 may have a first side 622 and a second side 624. In at least one aspect, first side 622 may be configured substantially similar to first side 122. In at least one aspect, second side 624 may be configured substantially similar to second side 124. Proof mass 620 may be coupled to beam 610 by at least one spring 628 and may be adjacent to at least one first opening 650. In at least one aspect, spring 628 may be configured substantially similar to spring 128.

[0102] The proof mass 620 can be configured in various arrangements relative to the beam. In the illustrative embodiment of Fig. 6, the proof mass 620 is disposed in the second portion 614 of the beam 610. The proof mass may be disposed in the first or third portion 612 or 616 of the beam. In the illustrative embodiment, the side 622 of the proof mass 620 is coupled to the beam 610 by springs 628. In the illustrative embodiment, the side 622 is substantially perpendicular to the first axis 692. The application is not limited in this regard, and a proof mass of any shape may be coupled to the beam by any of its sides. In the illustrative embodiment, the springs 628 are disposed along the second axis 694, which is substantially perpendicular to the first axis 692. The proof mass 620 pivots about the second axis 694 with respect to the beam 610. The second axis 694 may be disposed at any angle to the first axis 692.

[0103] The proof mass 620 may be adjacent to at least one first opening 650. In at least one aspect, the first opening 650 may be configured substantially similarly to the first opening 150. The first opening 650 may have a first side 652 and a second side 654. The first side 652 may be configured substantially similarly to the first side 152. The second side 654 may be configured substantially similarly to the second side 154. In the illustrative embodiment of Fig. 6, the first opening 650 surrounds the proof mass 620 and is surrounded by the beam 610. In the illustrative embodiment, the opening has a first side 652 adjacent the springs 628 that is wider than a second opening 656 from the springs beyond the proof mass.

[0104] The beam 610 may have a second opening 660 with a first side 662 and a second side 664 and may have a stub 668. The second opening 660 may be configured substantially similar to the second opening 160. The first side 662 may be configured substantially similar to the first side 162. The second side 664 may be configured substantially similar to the second side 164. The stub 668 may be configured substantially similar to the stub 168. In the illustrative embodiment of Fig. 6, there is a second opening 660 beyond the first axis 692 from the first opening 650 disposed in the first portion 612 on the beam 610. In the illustrative embodiment, the second opening has a first side 662 beyond the first axis 692 from the first side 652 of the first opening 650 that is wider than a second side 664 of the second opening disposed beyond the first axis 692 from the second side 654 of the first opening. The first side 662 of the second opening 660 may include at least one stub 668 configured to occupy substantially the same area as the springs 628.

[0105] In at least one aspect, the substrate may be configured substantially similar to substrate 130. The substrate may include a first electrode, a second electrode, and a self-test electrode. In at least one aspect, the first electrode may be configured substantially similar to first electrode 132. In at least one aspect, the second electrode may be configured substantially similar to second electrode 134. In at least one aspect, the self-test electrode may be configured substantially similar to self-test electrode 136.

[0106] In the illustrative embodiment of Fig. 6, the accelerometer 600 includes an armature 640. In at least one aspect, the armature 640 may be configured substantially similarly to the armature 140. The armature 640 may be coupled to the beam 610 by a spring 642. In at least one aspect, the spring 642 may be configured substantially similarly to the spring 142. Sixth alternative embodiment

[0107] An alternative embodiment of a z-axis accelerometer can be described with reference to Fig. 7. The accelerometer 700 may include a beam 710, a proof mass 720, a substrate, and at least one armature 740. The accelerometer 700 may include a proof mass 720 disposed in a first portion of the beam 710.

[0108] In at least one aspect, the beam 710 may be configured substantially similar to the beam 110. The beam 710 may be configured to pivot about a first axis 792. In at least one aspect, the first axis 792 may be configured substantially similar to the first axis 192. The beam 710 may include a first portion 712, a second portion 714, and a third portion 716. In at least one aspect, the first portion 712 may be configured substantially similar to the first portion 112. In at least one aspect, the second portion 714 may be configured substantially similar to the second portion 114. In at least one aspect, the third portion 716 may be configured substantially similar to the third portion 116.

[0109] In at least one aspect, proof mass 720 may be configured substantially similar to proof mass 120. Proof mass 720 may be configured to pivot about a second axis 794. In at least one aspect, second axis 794 may be configured substantially similar to second axis 194. Proof mass 720 may have a first side 722 and a second side 724. In at least one aspect, first side 722 may be configured substantially similar to first side 122. In at least one aspect, second side 724 may be configured substantially similar to second side 124. Proof mass 720 may be coupled to beam 710 by at least one spring 728 and may be adjacent to at least one first opening 750. In at least one aspect, spring 728 may be configured substantially similar to spring 128. In the illustrative embodiment of Fig. 7, the proof mass 720 is disposed within the first portion 716 of the beam 710. In the illustrative embodiment, the second side 724 of the proof mass 720 is coupled to the beam 710 by the springs 728. The first side 722 of the proof mass 720 may alternatively be coupled to the beam 710.

[0110] In at least one aspect, the first opening 750 may be configured substantially similarly to the first opening 150. The first opening 750 may have a first side 752 and a second side 754. The first side 752 may be configured substantially similarly to the first side 152. The second side 754 may be configured substantially similarly to the second side 154. In the illustrative embodiment of Fig. 7, the second side 754 of the first opening 750 is wider than the first side 752 of the first opening.

[0111] The beam 710 may have a second opening 760 with a first side 762 and a second side 764 and may have a stub 768. The second opening 760 may be configured substantially similar to the second opening 160. The first side 762 may be configured substantially similar to the first side 162. The second side 764 may be configured substantially similar to the second side 164. The stub 768 may be configured substantially similar to the stub 168. In the illustrative embodiment of Fig. 7, the second opening 760 is disposed in the second portion 714 of the beam 710. In the illustrative embodiment, the second side 764 of the second opening 760 is wider than the first side 762 of the second opening.

[0112] In at least one aspect, the substrate may be configured substantially similar to substrate 130. The substrate may include a first electrode, a second electrode, and a self-test electrode. In at least one aspect, the first electrode may be configured substantially similar to first electrode 132. In at least one aspect, the second electrode may be configured substantially similar to second electrode 134. In at least one aspect, the self-test electrode may be configured substantially similar to self-test electrode 136. In the illustrative embodiment of Fig. 7, the first electrode faces the second portion 714 of the beam 710. The second electrode faces the proof mass 720 disposed in the first portion 712 of the beam 710, and the self-test electrode faces the third portion 716 of the beam. In some embodiments, the first electrode may face the third portion of the beam, and the self-test electrode may face the second portion of the beam.

[0113] In the illustrative embodiment of Fig. 7, the accelerometer 700 includes an armature 740. In at least one aspect, the armature 740 may be configured substantially similarly to the armature 140. The armature 740 may be coupled to the beam 710 by a spring 742. In at least one aspect, the spring 742 may be configured substantially similarly to the spring 142. Seventh alternative embodiment

[0114] An alternative embodiment of a z-axis accelerometer can be described with reference to Fig. 8A-8C. The illustrative accelerometer 800 in Fig. 8A-8C may include a beam 810, a proof mass 820, a substrate 830, and at least one armature 840. The accelerometer 800 may include a proof mass 820 configured to translate relative to a pivot plane of the beam 810.

[0115] Fig. Figure 8A shows an illustration of an accelerometer 800 according to an embodiment of the present application when an acceleration of 0 g is applied in the z-direction. Fig. Figure 8B shows an illustration of an accelerometer 100 according to an embodiment of the present application when an acceleration of a magnitude greater than 0 g is applied in the z-direction. The illustration shows proof mass 820 translating out of plane with respect to beam 810. In some embodiments, proof mass 820 may translate vertically out of plane with respect to the plane of the beam. However, the application is not limited in this regard, and proof mass 820 may pivot and / or translate with respect to the beam.

[0116] As in Fig. 8C, in at least one aspect, the beam 810 may be configured substantially similar to the beam 110. The beam 810 may be configured to pivot about a first axis 892. In at least one aspect, the first axis 892 may be configured substantially similar to the first axis 192. The beam 810 may include a first portion 812, a second portion 814, and a third portion 816. In at least one aspect, the first portion 812 may be configured substantially similar to the first portion 112. In at least one aspect, the second portion 814 may be configured substantially similar to the second portion 114. In at least one aspect, the third portion 816 may be configured substantially similar to the third portion 116.

[0117] In at least one aspect, proof mass 820 may be configured substantially similarly to proof mass 120. Proof mass 820 may have a first side 822 and a second side 824. In at least one aspect, first side 822 may be configured substantially similarly to first side 122. In at least one aspect, second side 824 may be configured substantially similarly to second side 124. Proof mass 820 may be coupled to beam 810 by at least one spring 828 and may be adjacent to at least one first opening 850. In at least one aspect, spring 828 may be configured substantially similarly to spring 128. In the illustrative embodiment of Fig. 8C, the first side 822 of the proof mass 820 is coupled to the beam by four springs 828 and the second side 824 is coupled to the beam by four springs 828. In the illustrative embodiment of Fig. 8C, the springs 828 are flexural springs. However, the present application is not limited to any number of springs or to flexural springs, and any number of springs of any type may be coupled to the proof mass 820. The flexural springs may be configured such that the proof mass 820 translates and / or pivots in response to acceleration in the z-direction outside a pivot plane of the beam 810. The proof mass 820 may have a higher amplitude than a beam without a proof mass.

[0118] In at least one aspect, the first opening 850 may be configured substantially similarly to the first opening 150. The first opening 850 may have a first side 852 and a second side 854. The first side 852 may be configured substantially similarly to the first side 152. The second side 854 may be configured substantially similarly to the second side 154. In the illustrative embodiment of Fig. 8C, the first side 852 and the second side 854 have substantially equal widths.

[0119] The beam 810 may have a second opening 860 with a first side 862 and a second side 864 and may have a stub 868. The second opening 860 may be configured substantially similar to the second opening 160. The first side 862 may be configured substantially similar to the first side 162. The second side 864 may be configured substantially similar to the second side 164. The stub 868 may be configured substantially similar to the stub 168. In the illustrative embodiment of Fig. 8C, the first side 862 and the second side 864 have substantially the same width.

[0120] In at least one aspect, substrate 830 may be configured substantially similarly to substrate 130. Substrate 830 may include a first electrode 832, a second electrode 834, and a self-test electrode 836. In at least one aspect, first electrode 832 may be configured substantially similarly to first electrode 132. In at least one aspect, second electrode 834 may be configured substantially similarly to second electrode 134. In at least one aspect, self-test electrode 836 may be configured substantially similarly to self-test electrode 136.

[0121] In the illustrative embodiment of Fig. 8C, the accelerometer 800 includes an armature 840. In at least one aspect, the armature 840 may be configured substantially similarly to the armature 140. The armature 840 may be coupled to the beam 810 by a spring 842. In at least one aspect, the spring 842 may be configured substantially similarly to the spring 142.

[0122] It should be understood that, although the present disclosure describes various embodiments of single-axis accelerometers, two or more accelerometers according to the present disclosure may be used in conjunction to sense accelerations about two or more axes in the same device. In some embodiments, two or more accelerometers may sense accelerations about two or more perpendicular axes and may sense two or more accelerations simultaneously.

[0123] Some applications of some embodiments of the present application include low or high acceleration environments, including, but not limited to, automotive vehicles, wearables, and machine health monitoring.

[0124] Fig. Figure 9 illustrates a non-limiting example in which at least one accelerometer of the types described herein is used in a car. In the example of Fig. 9, a motor vehicle 900 includes a control unit 902 coupled to an onboard computer 904 of the car by a wired or wireless connection. The control unit 902 may include at least one accelerometer of the types described herein. As a non-limiting example, the at least one accelerometer may detect accelerations in the direction of travel and / or perpendicular to the direction of travel. The at least one accelerometer may also be configured to detect vertical accelerations, which may be useful, for example, to monitor the condition of a suspension of the motor vehicle 900. The control unit 902 may receive power and control signals from the onboard computer 904 and may provide output signals of the type described herein to the onboard computer 904.

[0125] Fig.10 illustrates a system 1000 including three z-axis MEMS accelerometers 1002a, 1002b, and 1002c of one or more of the types described herein coupled to a piece of industrial equipment 1004. Equipment 1004 may be a motor, although this is a non-limiting example. Accelerometers 1002a-1002c may be coupled to the equipment and configured to monitor vibration of the equipment with respect to a respective axis. For example, accelerometer 1002a may be oriented to detect a z-axis acceleration, accelerometer 1002b a y-axis acceleration, and accelerometer 1002c an x-axis acceleration. In an alternative embodiment, two or more of the accelerometers 1002a-1002c may be combined into a single package or housing, as opposed to the illustrated embodiment of three distinct housings.The system can wirelessly communicate acceleration data generated by the respective accelerometer. Power for the accelerometer circuitry can be obtained from the vibration of equipment 1004. Other embodiments are possible.

[0126] Various aspects of the present application may provide one or more advantages. Some examples are now listed. It should be understood that not all aspects necessarily provide all advantages, and advantages other than those listed may be provided by one or more aspects. According to some aspects of the present application, z-axis rocker accelerometers with increased sensitivity are provided. The increased sensitivity may be particularly noticeable or advantageous at high operating frequencies. For example, rocker accelerometers operating at frequencies between 2 kHz and 100 kHz (or any value within this range as a non-limiting example) may have increased sensitivity compared to conventional designs.

[0127] Having thus described some aspects and embodiments of the technology of this application, it is understood that various changes, modifications, and improvements will be readily apparent to one of ordinary skill in the art. Such changes, modifications, and improvements are intended to be within the spirit and scope of the technology described in this application. It is therefore to be understood that the foregoing embodiments are presented merely by way of example, and that inventive embodiments may be practiced otherwise than as specifically described within the scope of the appended claims and their equivalents.In addition, any combination of two or more features, systems, articles, materials, and / or methods described herein, if such features, systems, articles, materials, and / or methods are not mutually contradictory, is included within the scope of the present disclosure.

[0128] Furthermore, as described, some aspects may be practiced as one or more methods. The acts performed as part of the method may be arranged in any suitable manner. Accordingly, embodiments may be constructed in which acts are performed in a different order than illustrated, which may include performing some acts concurrently, even though they are shown as sequential acts in illustrated embodiments.

[0129] All definitions as defined and used herein should be construed as taking precedence over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0130] The terms "approximately," "substantially," and "about" may be used in some embodiments to mean within ±20% of a target value, in some embodiments within ±10% of a target value, in some embodiments within ±5% of a target value, or in some embodiments even within ±2% of a target value. The terms "approximately" and "about" may include the target value.

Claims

[1] Z-axis rocker accelerometer, which has: a substrate; an anchor; a beam connected to the substrate by the anchor and configured to pivot about a first axis, the first axis being parallel to the substrate, the beam being asymmetrical relative to the first axis; and a proof mass coupled to the beam and configured to pivot about a second axis different from the first axis relative to the beam, the proof mass being coupled to the beam on one side and the second axis being parallel to the one side and fixed in a plane with the beam. [2] The accelerometer of claim 1, wherein the proof mass has a first side proximate the first axis and a second side distal from the first axis, and wherein the one side of the proof mass coupled to the beam is the first side. [3] The accelerometer of claim 1, wherein the proof mass has a first side proximate the first axis and a second side distal from the first axis, and wherein the one side of the proof mass coupled to the beam is the second side. [4] The accelerometer of claim 1, wherein the beam further comprises: a spring coupled to the beam and the test mass; a plurality of stubs arranged on an opposite side of the first axis from the spring; wherein the stubs are designed so that they occupy substantially the same amount of area of ​​the beam as the spring. [5] The accelerometer of claim 1, wherein the armature is centered relative to the beam in a direction perpendicular to the first axis. [6] The accelerometer of claim 1, wherein the beam comprises a first portion and a second portion separated by the first axis, the second portion having a greater mass than the first portion, the proof mass being coupled to the first portion of the beam. [7] The accelerometer of claim 1, wherein the beam comprises a first portion and a second portion separated by the first axis, the second portion having a greater mass than the first portion, the proof mass being coupled to the second portion of the beam. [8] The accelerometer of claim 1, further comprising circuitry disposed on the substrate and configured to detect a capacitance between the substrate and the proof mass. [9] The accelerometer of claim 1, further comprising an electrode disposed on the substrate, wherein the proof mass is configured to be spaced from the electrode by a shorter distance than the beam upon pivoting the proof mass toward the electrode. [10] The accelerometer of claim 1, wherein the second axis is substantially parallel to the first axis. [11] A method of operating a z-axis accelerometer, the accelerometer comprising a substrate, an armature, a beam connected to the substrate by the armature, and a proof mass coupled to the beam, the method comprising: Detecting an indication of a position of a first position of the beam relative to the substrate using a first detection capacitance, Detecting an indication of a position of the proof mass relative to the substrate using a second sensing capacitance, wherein the proof mass is coupled to a second portion of the beam, and Outputting a signal indicative of the first detection capacity and the second detection capacity, wherein the beam is configured to pivot about a first axis, the first axis being parallel to the substrate; wherein the proof mass is configured to pivot about a second axis other than the first axis and parallel to the substrate relative to the beam; wherein the first sensing capacitance has a first amplitude; wherein the second sensing capacitance has a second amplitude that is greater than the first amplitude; and wherein outputting the signal comprises outputting a difference of the first and second capacitances. [12] The method of claim 11, further comprising pivoting the proof mass relative to the beam by moving a free side of the proof mass positioned between the first axis and a point of connection of the proof mass to the beam. [13] The method of claim 11, further comprising pivoting the proof mass relative to the beam by moving a free side of the proof mass separated from the first axis by a connection point of the proof mass to the beam. [14] The method of claim 11, wherein the proof mass is a first proof mass, and wherein the z-axis accelerometer comprises a second proof mass configured to pivot relative to the beam, the method further comprising sensing a position of the second proof mass relative to the substrate. [15] Z-axis accelerometer, which has: a substrate; an anchor; a beam connected to the substrate by the anchor and configured to pivot about a first axis, the first axis being parallel to the substrate; a test mass embedded in the beam and configured for vertical displacement relative to a pivoting plane of the beam; and a circuit arrangement arranged on the substrate and configured to detect a first capacitance of a first capacitor formed by the substrate and the beam and a second capacitance of a second capacitor formed by the substrate and the proof mass. [16] The Z-axis accelerometer of claim 15, wherein the beam has an asymmetric mass relative to the first axis, including a first mass portion on a first side of the first axis and a second mass portion on a second side of the first axis, the first mass portion being larger than the second mass portion, and the proof mass being embedded in the first mass portion. [17] The Z-axis accelerometer of claim 15, wherein the beam has an asymmetric mass relative to the first axis, including a first mass portion on a first side of the first axis and a second mass portion on a second side of the first axis, the first mass portion being larger than the second mass portion, and the proof mass being embedded in the second mass portion. [18] The Z-axis accelerometer of claim 15, wherein the circuitry is configured to process at least one signal representing the first and second capacitances. [19] The Z-axis accelerometer of claim 15, wherein the beam is asymmetric with respect to the first axis and wherein the proof mass is embedded in the beam on one side of the first axis.

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