Accelerometer

Abstract

An accelerometer, comprising a substrate, a first anchor (31), an inner mass unit (1), an outer mass unit (2), a first seesaw unit (4), a second seesaw unit (5), a first acceleration measurement unit (6) and a second acceleration measurement unit. The first anchor (31) is fixed at a central portion of the substrate; the inner mass unit (1) surrounds the outer side of the first anchor (31); the outer mass unit (2) surrounds the outer side of the inner mass unit (1); the first seesaw unit (4) and the second seesaw unit (5) are arranged opposite to each other, and define an annular structure; the annular structure surrounds the outer side of the outer mass unit (2); the first acceleration measurement unit (6) is at least partially arranged on the annular structure and is used for measuring the acceleration in an out-of-plane Z-axis direction; the second acceleration measurement unit is arranged on the outer mass unit (2) and is used for measuring the acceleration in an in-plane X-axis direction and the acceleration in an in-plane Y-axis direction. The accelerometer can achieve the technical effects of reasonable design and higher sensitivity.

Description

An acceleration sensor Technical Field

[0001] The present invention belongs to the technical field of sensors, and in particular relates to an acceleration sensor. Background Art

[0002] Acceleration sensors include one or more proof masses for detecting acceleration. For example, some acceleration sensors include a proof mass configured to move within a plane to detect acceleration in the plane of the proof mass, and the proof mass configured to move out of plane to detect acceleration perpendicular to the plane of the proof mass. Acceleration can be detected using a capacitive sensor coupled to the proof mass.

[0003] Currently, acceleration sensors have technical problems such as low sensitivity and low space utilization. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art and provide a new technical solution for an acceleration sensor.

[0005] According to one aspect of the present invention, there is provided an acceleration sensor, comprising:

[0006] a base and a first anchor point, wherein the first anchor point is fixed to a middle portion of the base;

[0007] an inner mass unit and an outer mass unit, wherein the inner mass unit surrounds the outer side of the first anchor point and is elastically connected to the first anchor point, and the outer mass unit surrounds the outer side of the inner mass unit and is elastically connected to the inner mass unit;

[0008] a first seesaw unit and a second seesaw unit, wherein the first seesaw unit and the second seesaw unit are arranged opposite to each other and the two enclose an annular structure; the annular structure surrounds the outer side of the outer mass unit and is elastically connected to the outer mass unit;

[0009] a first acceleration detection unit and a second acceleration detection unit, wherein at least a portion of the first acceleration detection unit is disposed in the annular structure and is used to detect acceleration along an out-of-plane Z-axis direction; and a second acceleration detection unit is disposed in the outer mass unit and is used to detect acceleration along an in-plane X-axis direction and an in-plane Y-axis direction;

[0010] The out-of-plane Z-axis direction, the in-plane X-axis direction, and the in-plane Y-axis direction are perpendicular to each other.

[0011] Optionally, the acceleration sensor further includes a first elastic member and a second elastic member; an extending direction of the first elastic member is perpendicular to an extending direction of the second elastic member;

[0012] The inner mass unit is elastically connected to the first anchor point via the first elastic member; the outer mass unit is elastically connected to the inner mass unit via the second elastic member.

[0013] Optionally, the first elastic member is an X-axis single-degree-of-freedom spring, and the second elastic member is a Y-axis single-degree-of-freedom spring;

[0014] Alternatively, the first elastic member is a Y-axis single-degree-of-freedom spring, and the second elastic member is an X-axis single-degree-of-freedom spring.

[0015] Optionally, the X-axis single-degree-of-freedom spring is serpentine and / or U-shaped;

[0016] The Y-axis single-degree-of-freedom spring is serpentine and / or U-shaped.

[0017] Optionally, the second acceleration detection unit includes an X-axis detection capacitor group and a Y-axis detection capacitor group provided on the outer mass unit;

[0018] The X-axis detection capacitor group is symmetrically arranged along the in-plane X-axis, and the X-axis detection capacitor group is symmetrically arranged along the in-plane Y-axis; the X-axis detection capacitor group is used to detect acceleration along the in-plane X-axis direction;

[0019] The Y-axis detection capacitor group is symmetrically arranged along the Y-axis in the plane, and the Y-axis detection capacitor group is symmetrically arranged along the X-axis in the plane; the Y-axis detection capacitor group is used to detect acceleration along the Y-axis direction in the plane.

[0020] Optionally, the X-axis detection capacitor group includes a movable capacitor plate disposed on a side wall of the outer mass unit, and a first fixed capacitor plate and a second fixed capacitor plate fixed to the substrate; wherein the first fixed capacitor plate and the second fixed capacitor plate are parallel to and spaced apart from each other, and the first fixed capacitor plate and the second fixed capacitor plate are both distributed along the in-plane Y-axis direction;

[0021] The first fixed capacitor plate and the second fixed capacitor plate are respectively arranged differentially from the movable capacitor plate on the side wall of the outer mass unit.

[0022] Optionally, the X-axis detection capacitor group includes a first movable comb-tooth capacitor plate provided on the outer mass unit and a first fixed comb-tooth capacitor plate fixed on the substrate;

[0023] The first movable comb-teeth capacitor plates distributed along the in-plane X-axis direction and the first fixed comb-teeth capacitor plates cooperate to form a first comb-teeth capacitor.

[0024] Optionally, the Y-axis detection capacitor group includes a movable electrode arranged on the side wall of the outer mass unit, a third fixed capacitor plate fixed on the substrate, and a fourth fixed capacitor plate; wherein the third fixed capacitor plate and the fourth fixed capacitor plate are arranged parallel to and spaced apart from each other;

[0025] The third fixed capacitor plate and the fourth fixed capacitor plate are respectively disposed differentially from the movable electrode on the side wall of the outer mass unit.

[0026] Optionally, the Y-axis detection capacitor group includes a second movable comb-tooth capacitor plate provided on the outer mass unit and a second fixed comb-tooth capacitor plate fixed on the base;

[0027] The second movable comb-teeth capacitor plates distributed along the in-plane Y-axis direction and the second fixed comb-teeth capacitor plates cooperate to form a second comb-teeth capacitor.

[0028] Optionally, the first fixed comb-tooth capacitor plate is fixed to the substrate via a second anchor point; the second fixed comb-tooth capacitor plate is fixed to the substrate via a third anchor point;

[0029] The second anchor point and the third anchor point are both close to the first anchor point.

[0030] Optionally, the first seesaw unit is elastically connected to one end of the outer mass unit, and the second seesaw unit is elastically connected to the other end of the outer mass unit; the first seesaw unit and the second seesaw unit are symmetrically distributed along the symmetry axis of the acceleration sensor; the first seesaw unit forms two first seesaw structures on both sides of the symmetry axis, and the two first seesaw structures rotate along the first rotation axis; the second seesaw unit forms two second seesaw structures on both sides of the symmetry axis, and the two second seesaw structures rotate along the second rotation axis; the first rotation axis and the second rotation axis are both distributed along the in-plane Y-axis direction, and the symmetry axis is distributed along the in-plane X-axis direction.

[0031] Optionally, the acceleration sensor further comprises a coupling beam;

[0032] Part of the second seesaw unit is sleeved on the outside of part of the first seesaw unit to form a nested structure, the coupling beam is located in the nested structure, and one end of the coupling beam is connected to the first seesaw unit, and the other end is connected to the second seesaw unit.

[0033] A technical effect of the present invention is:

[0034] In the embodiment of the present application, the acceleration sensor is reasonably designed, and the detection mass in the out-of-plane Z-axis direction is set in the annular structure; and the detection mass in the in-plane X-axis direction at least includes the detection mass set in the outer mass unit and the detection mass set in the annular structure; at the same time, the detection mass in the in-plane Y-axis direction at least includes the detection mass set in the outer mass unit and the detection mass set in the annular structure. This layout of shared inspection mass enables the acceleration sensor to have higher space utilization, thereby having higher sensitivity under the same area. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG1 is a schematic structural diagram of an acceleration sensor according to a first embodiment of the present invention;

[0036] 2 is a schematic diagram of a detection mode in the in-plane X-axis direction of the acceleration sensor according to the first embodiment of the present invention;

[0037] 3 is a schematic diagram of the detection mode of the acceleration sensor in the Y-axis direction in the plane of the first embodiment of the present invention;

[0038] 4 is a schematic diagram of the detection mode of the acceleration sensor in the out-of-plane Z-axis direction according to the first embodiment of the present invention;

[0039] 5 is a schematic diagram of the parasitic modes of the acceleration sensor in the out-of-plane Z-axis direction according to the first embodiment of the present invention;

[0040] FIG6 is a schematic structural diagram of a coupling beam of an acceleration sensor according to the first embodiment of the present invention;

[0041] FIG7 is a schematic structural diagram of an acceleration sensor according to a second embodiment of the present invention;

[0042] 8 is a schematic diagram of the detection mode of the acceleration sensor in the in-plane X-axis direction according to the second embodiment of the present invention;

[0043] 9 is a schematic diagram of the detection mode of the acceleration sensor in the Y-axis direction in the plane according to the second embodiment of the present invention;

[0044] 10 is a schematic diagram of the detection mode of the acceleration sensor in the out-of-plane Z-axis direction according to the second embodiment of the present invention;

[0045] FIG11 is a schematic diagram of the out-of-plane parasitic modes in the Z-axis direction of the acceleration sensor according to the second embodiment of the present invention;

[0046] FIG12 is a schematic structural diagram of a coupling beam of an acceleration sensor according to a second embodiment of the present invention;

[0047] FIG13 is a schematic structural diagram of an acceleration sensor according to a third embodiment of the present invention;

[0048] 14 is a schematic diagram of the detection mode of the acceleration sensor in the in-plane X-axis direction according to the third embodiment of the present invention;

[0049] 15 is a schematic diagram of the detection mode of the acceleration sensor in the Y-axis direction in the plane according to the third embodiment of the present invention;

[0050] 16 is a schematic diagram of the detection mode of the acceleration sensor in the out-of-plane Z-axis direction according to the third embodiment of the present invention;

[0051] FIG17 is a schematic diagram of the out-of-plane parasitic modes in the Z-axis direction of the acceleration sensor according to the third embodiment of the present invention;

[0052] FIG18 is a schematic structural diagram of a coupling beam of an acceleration sensor according to a third embodiment of the present invention;

[0053] FIG19 is a schematic structural diagram of an X-axis detection capacitor group and a Y-axis detection capacitor group in an acceleration sensor according to a third embodiment of the present invention;

[0054] FIG20 is a schematic structural diagram of an X-axis detection capacitor group in an acceleration sensor according to the first and second embodiments of the present invention;

[0055] FIG21 is a schematic structural diagram of a Y-axis detection capacitor group in an acceleration sensor according to the first and second embodiments of the present invention.

[0056] In the figure: 100, axis of symmetry; 200, first rotation axis; 300, second rotation axis; 1, inner mass unit; 2, outer mass unit; 31, first anchor point; 32, second anchor point; 33, third anchor point; 4, first seesaw unit; 5, second seesaw unit; 6, first acceleration detection unit; 71, X-axis detection capacitor group; 711, first through hole; 712, first fixed capacitor plate; 713, second fixed capacitor plate; 714, First fixed comb-tooth capacitor plate; 715, first movable comb-tooth capacitor plate; 72, Y-axis detection capacitor group; 721, second through hole; 722, third fixed capacitor plate; 723, fourth fixed capacitor plate; 724, second fixed comb-tooth capacitor plate; 725, second movable comb-tooth capacitor plate; 81, first elastic member; 82, second elastic member; 9, coupling beam; 10, first out-of-plane detection mass; 11, second out-of-plane detection mass. DETAILED DESCRIPTION

[0057] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0058] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0059] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly refer to one or more of the features. Throughout the description of this application, unless otherwise specified, "plurality" means two or more. Furthermore, "and / or" in the specification and claims refers to at least one of the connected entities, and the character " / " generally indicates an "or" relationship between the connected entities.

[0060] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0061] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances. Example 1

[0062] Referring to Figures 1 to 6 , an acceleration sensor is provided according to one aspect of the present invention. To facilitate description of the acceleration sensor of the present invention, a three-dimensional XYZ coordinate system is established, defining an in-plane X-axis direction, an in-plane Y-axis direction, and an out-plane Z-axis direction. The in-plane X-axis direction, the in-plane Y-axis direction, and the out-plane Z-axis direction are mutually perpendicular.

[0063] Specifically, the acceleration sensor includes a substrate, a first anchor point 31 , an inner mass unit 1 , an outer mass unit 2 , a first seesaw unit 4 , a second seesaw unit 5 , a first acceleration detection unit 6 , and a second acceleration detection unit.

[0064] Exemplarily, the two first anchor points 31 are symmetrically distributed along the in-plane X-axis.

[0065] More specifically, the first anchor point 31 is fixed to the middle of the base; the inner mass unit 1 surrounds the outer side of the first anchor point 31 and is elastically connected to the first anchor point 31, and the outer mass unit 2 surrounds the outer side of the inner mass unit 1 and is elastically connected to the inner mass unit 1; the first seesaw unit 4 and the second seesaw unit 5 are arranged opposite to each other, and the two together form an annular structure; the annular structure surrounds the outer side of the outer mass unit 2 and is elastically connected to the outer mass unit 2, for example, the annular structure is elastically connected to the outer mass unit 2 via a torsion spring; at least part of the first acceleration detection unit 6 is arranged in the annular structure for detecting acceleration along the out-of-plane Z-axis direction; the second acceleration detection unit is arranged in the outer mass unit 2 for detecting acceleration along the in-plane X-axis direction and the in-plane Y-axis direction. The out-of-plane Z-axis direction, the in-plane X-axis direction, and the in-plane Y-axis direction are perpendicular to each other.

[0066] The first acceleration detection unit 6 is used to detect the rotation of the seesaw caused by the movement of the inspection mass on the annular structure formed by the first seesaw unit 4 and the second seesaw unit 5 along the out-of-plane Z-axis direction due to the out-of-plane acceleration, and the second acceleration detection unit is used to detect the translational motion caused by the movement of the inspection mass on the outer mass unit 2 along the in-plane X-axis direction and the in-plane Y-axis direction due to the in-plane acceleration.

[0067] In the embodiment of the present application, the acceleration sensor is reasonably designed, and the detection mass in the out-of-plane Z-axis direction is set in the annular structure; and the detection mass in the in-plane X-axis direction at least includes the detection mass set in the outer mass unit 2 and the detection mass set in the annular structure; at the same time, the detection mass in the in-plane Y-axis direction at least includes the detection mass set in the outer mass unit 2 and the detection mass set in the annular structure. This layout of shared inspection mass enables the acceleration sensor to have higher space utilization, thereby having higher sensitivity under the same area.

[0068] It should be noted that the annular structure formed by the first seesaw unit 4 and the second seesaw unit 5 is elastically connected to the outer mass unit 2 to provide support for the proof mass block on the annular structure when it undergoes linear motion along the in-plane X-axis and the in-plane Y-axis. Simultaneously, the outer mass unit 2 is elastically connected to the inner mass unit 1, and the inner mass unit 1 is elastically connected to the first anchor point 31. For example, the outer mass unit and the inner mass unit are connected by a second elastic connector, and the second elastic connector is parallel to the in-plane Y-axis. In this case, the second elastic connector provides flexible support for the outer mass unit and the annular structure (i.e., the first seesaw unit and the second seesaw unit) to move along the in-plane X-axis. In this case, the first elastic connector elastically connecting the inner mass unit (mass unit) to the first anchor point is parallel to the in-plane X-axis, and the first elastic connector provides flexible support for the inner mass unit, the outer mass unit, and the annular structure to move along the in-plane Y-axis.

[0069] For another example, the outer mass unit and the inner mass unit are connected by a second elastic connector, and the second elastic connector is parallel to the in-plane X-axis. Then, the second elastic connector provides flexible support for the outer mass unit and the annular structure (i.e., the first seesaw unit and the second seesaw unit) to move along the in-plane Y-axis direction. At this time, the first elastic connector elastically connected between the inner mass unit (mass unit) and the first anchor point is parallel to the in-plane Y-axis. The first elastic connector provides flexible support for the inner mass unit, the outer mass unit, and the annular structure to move along the in-plane X-axis direction.

[0070] Exemplarily, the acceleration sensors are symmetrically distributed along their symmetry axis 100 ; and the first seesaw unit 4 and the second seesaw unit 5 are both symmetrically distributed along the symmetry axis 100 .

[0071] Optionally, the acceleration sensor further includes a first elastic member 81 and a second elastic member 82; the extending direction of the first elastic member 81 is perpendicular to the extending direction of the second elastic member 82;

[0072] The inner mass unit 1 is elastically connected to the first anchor point 31 via the first elastic member 81, and the outer mass unit 2 is elastically connected to the inner mass unit 1 via the second elastic member 82. This simplifies the connection between the outer mass unit 2, the inner mass unit 1, and the first anchor point 31, facilitating movement of the second acceleration detection unit on the outer mass unit 2 along the in-plane X-axis and the in-plane Y-axis, thereby facilitating the acceleration sensor's ability to detect acceleration along the in-plane X-axis and the in-plane Y-axis.

[0073] In an embodiment of the present application, the first anchor point 31 is arranged at the center of the structure of the acceleration sensor, and the annular structure formed by the inner mass unit 1, the outer mass unit 2, and the first seesaw unit 4 and the second seesaw unit 5 shares the first anchor point 31 through the first elastic member 81 and the second elastic member 82, so that the overall structure of the acceleration sensor is less affected by factors such as stress, thereby significantly improving the anti-interference ability of the acceleration sensor.

[0074] Optionally, the first elastic member 81 is an X-axis single-degree-of-freedom spring, and the second elastic member 82 is a Y-axis single-degree-of-freedom spring. The anchor point, the detection mass of the outer mass unit 2, and the detection mass of the inner mass unit 1 can be set according to the layout requirements of the substrate, and this application does not limit this.

[0075] In the above embodiment, the proof masses in the in-plane X-axis direction include the proof masses provided on outer mass unit 2, the proof masses provided on inner mass unit 1, and the proof masses provided in the annular structure. The proof masses in the in-plane Y-axis direction include the proof masses provided on outer mass unit 2 and the proof masses provided in the annular structure. This shared proof mass layout helps further enhance the sensitivity of the accelerometer within the same area, achieving higher space utilization.

[0076] Optionally, the X-axis single-degree-of-freedom spring is serpentine-shaped; the Y-axis single-degree-of-freedom spring is serpentine-shaped. The X-axis single-degree-of-freedom spring and the Y-axis single-degree-of-freedom spring are rationally designed to facilitate movement of the proof mass on the outer mass unit 2 along the in-plane X-axis direction and the in-plane Y-axis direction.

[0077] Optionally, the second acceleration detection unit includes an X-axis detection capacitor group 71 and a Y-axis detection capacitor group 72 provided on the outer mass unit 2;

[0078] The X-axis detection capacitor group 71 is symmetrically arranged along the in-plane X-axis, and the X-axis detection capacitor group 71 is symmetrically arranged along the in-plane Y-axis; the X-axis detection capacitor group 71 is used to detect acceleration along the in-plane X-axis direction;

[0079] The Y-axis detection capacitor group 72 is symmetrically arranged along the in-plane Y-axis, and the Y-axis detection capacitor group 72 is symmetrically arranged along the in-plane X-axis; the Y-axis detection capacitor group 72 is used to detect acceleration along the in-plane Y-axis direction.

[0080] In the above embodiment, the structural design of the second acceleration detection unit is reasonable, which helps to accurately detect the acceleration along the in-plane X-axis direction and the in-plane Y-axis direction.

[0081] Optionally, referring to FIG20 , the X-axis detection capacitor group 71 includes a movable capacitor plate disposed on the side wall of the outer mass unit, and a first fixed capacitor plate 712 and a second fixed capacitor plate 713 fixed to the base; wherein the first fixed capacitor plate 712 and the second fixed capacitor plate 713 are parallel to and spaced apart from each other, and the first fixed capacitor plate 712 and the second fixed capacitor plate 713 are both distributed along the in-plane Y-axis direction;

[0082] The first fixed capacitor plate 712 and the second fixed capacitor plate 713 are respectively disposed differentially from the movable capacitor plates on the side walls of the outer mass unit.

[0083] For example, a first through hole 711 penetrating through the base is provided on the outer mass unit 2, a first fixed capacitor plate 712 and a second fixed capacitor plate 713 are both provided in the first through hole 711, and a movable capacitor plate is provided on the side wall at the corresponding position of the outer mass unit (i.e., the side wall of the first through hole).

[0084] It should be noted that when the outer mass unit 2 is displaced to the left by the acceleration along the in-plane X-axis, the capacitance distance of the first differential detection capacitor formed by the first capacitor plate 712 and the movable capacitor plate on the side wall of the outer mass unit 2 increases, and the capacitance distance of the second differential detection capacitor formed by the second capacitor plate 713 and the movable capacitor plate on the side wall of the outer mass unit 2 decreases. The first differential detection capacitor and the second differential detection capacitor have a capacitance difference change proportional to the acceleration to the left along the in-plane X-axis. By detecting the change in the capacitance difference, the real-time value of the acceleration to the left along the in-plane X-axis can be obtained.

[0085] Similarly, when the outer mass unit 2 is displaced to the right by the acceleration along the in-plane X-axis, the real-time value of the acceleration to the right along the in-plane X-axis can also be obtained by detecting the change in the capacitance difference.

[0086] In the above embodiment, the structural design of the X-axis detection capacitor group 71 is relatively reasonable, which helps to accurately detect the acceleration along the in-plane X-axis direction.

[0087] Optionally, referring to FIG. 21 , the Y-axis detection capacitor group 72 includes a movable electrode disposed on the side wall of the outer mass unit, a third fixed capacitor plate 722 fixed to the substrate, and a fourth fixed capacitor plate 723 ; wherein the third fixed capacitor plate 722 and the fourth fixed capacitor plate 723 are parallel to and spaced apart from each other;

[0088] The third fixed capacitor plate 722 and the fourth fixed capacitor plate 723 are respectively disposed differentially from the movable electrodes on the sidewalls of the outer mass unit.

[0089] For example, a second through hole 721 penetrating through the base is provided on the outer mass unit 2, the third fixed capacitor plate 722 and the fourth fixed capacitor plate 723 are both provided in the second through hole 721, and a movable capacitor plate is provided on the side wall at the corresponding position of the outer mass unit (i.e., the side wall of the first through hole).

[0090] It should be noted that when the outer mass unit 2 is displaced upward by the acceleration along the in-plane Y-axis, the capacitance distance of the third differential detection capacitor formed by the third capacitor plate 722 and the movable capacitor plate on the side wall of the outer mass unit 2 increases, and the capacitance distance of the fourth differential detection capacitor formed by the fourth capacitor plate 723 and the movable capacitor plate on the side wall of the outer mass unit 2 decreases. The capacitance difference between the third differential detection capacitor and the fourth differential detection capacitor changes in proportion to the acceleration along the in-plane Y-axis. By detecting the change in the capacitance difference, the real-time value of the acceleration to the left along the in-plane Y-axis can be obtained.

[0091] Similarly, when the second detection mass block 721 is displaced downward by the downward acceleration along the in-plane Y-axis, the real-time value of the acceleration to the right along the in-plane Y-axis can also be obtained by detecting the change in the capacitance difference.

[0092] In the above embodiment, the structural design of the Y-axis detection capacitor group 72 is relatively reasonable, which helps to accurately detect the acceleration along the in-plane Y-axis direction.

[0093] Optionally, the first seesaw unit 4 is elastically connected to one end of the outer mass unit 2, and the second seesaw unit 5 is elastically connected to the other end of the outer mass unit 2; the first seesaw unit 4 and the second seesaw unit 5 are symmetrically distributed along the symmetry axis 100 of the acceleration sensor; the first seesaw unit 4 forms two first seesaw structures on both sides of the symmetry axis 100, and the two first seesaw structures rotate along the first rotation axis 200; the second seesaw unit 5 forms two second seesaw structures on both sides of the symmetry axis 100, and the two second seesaw structures rotate along the second rotation axis 300; the first rotation axis 200 and the second rotation axis 300 are both distributed along the in-plane Y-axis direction, and the symmetry axis 100 is distributed along the in-plane X-axis direction.

[0094] In the above-described embodiment, the first seesaw unit 4 and the second seesaw unit 5 are used as the out-of-plane acceleration detection structure, enabling the first seesaw unit 4 and the second seesaw unit 5 to rotate in opposite directions along the in-plane Y-axis direction under the influence of out-of-plane Z-axis acceleration. Thus, the out-of-plane acceleration (i.e., Z-axis acceleration) of the acceleration sensor can be detected by the first acceleration detection unit 6 disposed on the first seesaw unit 4 and the second seesaw unit 5. Furthermore, when the two first seesaw structures or the two second seesaw structures are subjected to undesirable Y-axis angular acceleration, the two first seesaw structures or the two second seesaw structures rotate in the same direction. The capacitance changes of the first acceleration detection units 6 caused by this same rotation are offset when detected by the first acceleration detection units 6. Therefore, the layout of the two first seesaw structures and the two second seesaw structures significantly reduces the influence of Y-axis angular acceleration on the acceleration sensor, thereby improving the cross-rejection ratio of the acceleration sensor and enhancing the accuracy of the acceleration sensor in detecting out-of-plane acceleration.

[0095] Optionally, a first groove is provided on the outer side of the first seesaw unit 4, and a second groove is provided on the inner side of the second seesaw unit 5, part of the first seesaw unit 4 is embedded in the second groove and part of the second seesaw unit 5 is embedded in the first groove to form a nested structure, and the nested structure is located between the first rotating shaft 200 and the second rotating shaft 300.

[0096] In the above embodiment, a nested structure is adopted between the first seesaw unit 4 and the second seesaw unit 5. This nested structure helps to extend the rotation arms of the first seesaw unit 4 and the second seesaw unit 5. At the same time, the first acceleration detection unit 6 can be arranged in an area farther from the rotation axis, thereby increasing the gain of out-of-plane acceleration detection.

[0097] Optionally, referring to FIG7 , the acceleration sensor further includes a first out-of-plane detection mass block 10 and a second out-of-plane detection mass block 11 ;

[0098] Each of the first seesaw structures includes a first sub-rotating portion and a second sub-rotating portion, the first sub-rotating portion and the second sub-rotating portion are respectively located on opposite sides of the first rotating shaft 200, and a first groove is provided on the outer side of the second sub-rotating portion; each of the second seesaw structures includes a third sub-rotating portion and a fourth sub-rotating portion, the third sub-rotating portion and the fourth sub-rotating portion are respectively located on opposite sides of the second rotating shaft 300, and a second groove is provided on the inner side of the third sub-rotating portion; a portion of the second sub-rotating portion is embedded in the second groove, and a portion of the third sub-rotating portion is embedded in the first groove;

[0099] The first out-of-plane detection mass block 10 is located at the first sub-rotation part, and the second out-of-plane detection mass block 11 is located at the fourth sub-rotation part.

[0100] In the above embodiment, the first out-of-plane detection mass block 10 forms an asymmetric detection mass block of the first seesaw unit, and the second out-of-plane detection mass block 11 forms an asymmetric detection mass block of the second seesaw unit. The first out-of-plane detection mass block 10 and the second out-of-plane detection mass block 11 are both located at the far end of the seesaw structure, so that the first seesaw structure and the second seesaw structure are more sensitive to the out-of-plane acceleration, thereby improving the gain of the acceleration sensor detection.

[0101] Exemplarily, a first out-of-plane detection mass block 10 is set at the position where the two first sub-rotating parts are connected, and a second out-of-plane detection mass block 11 is set at the position where the two fourth sub-rotating parts are connected, which helps to further increase the distance between the detection mass and the rotation axis, making the first seesaw structure and the second seesaw structure more sensitive to the out-of-plane acceleration, so as to further improve the gain of the acceleration sensor detection.

[0102] Optionally, the acceleration sensor further includes a coupling beam 9;

[0103] Part of the second seesaw unit 5 is mounted on the outside of part of the first seesaw unit 4 to form a nested structure. The coupling beam 9 is located in the nested structure, and one end of the coupling beam 9 is connected to the first seesaw unit 4, and the other end is connected to the second seesaw unit 5.

[0104] In the above embodiment, by setting a coupling beam 9 between the first seesaw unit 4 and the second seesaw unit 5, the coupling beam 9 can weaken the same-direction rotation of the first seesaw unit 4 and the second seesaw unit 5, further suppress the influence of the y-axis angular acceleration, and help to further improve the accuracy of the acceleration sensor in detecting external acceleration.

[0105] In a specific embodiment, the coupling beam 9 extends in a direction perpendicular to the symmetry axis 100 , and one end of the coupling beam 9 is connected to the second sub-rotation part, and the other end is connected to the third sub-rotation part.

[0106] In a specific embodiment, first acceleration detection units 6 are provided on the first sub-rotating portion, the second sub-rotating portion, the third sub-rotating portion, and the fourth sub-rotating portion. Some of the first acceleration detection units 6 are located on the first seesaw portion 4 away from the first rotation axis 200, and some of the first acceleration detection units 6 are located on the second seesaw portion 5 away from the second rotation axis 300. The multiple first acceleration detection units 6 are symmetrically distributed along the symmetry axis 100.

[0107] For example, the coupling beam 9 is in a bar shape, and one end of the coupling beam 9 is fixed to the bottom wall of the first groove, and the other end is fixed to the bottom wall of the second groove. This makes the structure of the coupling beam 9 relatively simple, and facilitates the assembly of the acceleration sensor.

[0108] In some embodiments, the coupling beam 9 includes two parallel sub-beams. One end of each sub-beam is fixed to the bottom wall of the first groove, and the other end is fixed to the bottom wall of the second groove. This further improves the ability of the coupling beam 9 to weaken the co-directional rotation of the first seesaw unit 4 and the second seesaw unit 5, thereby better suppressing the influence of y-axis angular acceleration.

[0109] In other embodiments, the coupling beam 9 is in the form of a rectangular ring. The middle portion of one side of the coupling beam 9 is fixed to the inner wall of the first groove, and the middle portion of the other side of the coupling beam 9 is fixed to the inner wall of the second groove. This makes the structural design of the coupling beam 9 more reasonable and effectively reduces the ability of the first seesaw unit 4 and the second seesaw unit 5 to rotate in the same direction.

[0110] In one embodiment, the first acceleration detection unit 6 includes a first out-of-plane detection capacitor plate and a second out-of-plane detection capacitor plate, which are opposite to each other and constitute a capacitor plate structure. The first out-of-plane detection capacitor plate is located on the base or the cavity cover, and the second out-of-plane detection capacitor plate is located on the first seesaw unit 4 and the second seesaw unit 5.

[0111] In this embodiment, the first acceleration detection unit 6 detects acceleration along the out-of-plane Z-axis direction (i.e., out-of-plane acceleration), causing the first seesaw unit 4 and the second seesaw unit 5 to rotate in opposite directions. However, in a parasitic mode, the first seesaw unit 4 and the second seesaw unit 5 rotate in the same direction about the Y-axis under the action of the Y-axis angular acceleration. To reduce the influence of the parasitic mode, a coupling beam 9 is connected between the first seesaw unit 4 and the second seesaw unit 5 to reduce the influence of the parasitic mode, that is, to reduce the same-direction rotation of the first seesaw unit 4 and the second seesaw unit 5 about the Y-axis. This further improves the cross-rejection ratio of the accelerometer and significantly enhances the detection accuracy of the acceleration sensor. The parasitic mode is when the acceleration sensor is affected by both the out-of-plane Z-axis acceleration and the Y-axis angular acceleration. Example 2

[0112] This embodiment provides another acceleration sensor, the structure of which is substantially the same as that of the embodiment 1, and only the different parts are described below.

[0113] Referring to Figures 7 to 12 , the first elastic member 81 is a Y-axis single-degree-of-freedom spring, and the second elastic member 82 is an X-axis single-degree-of-freedom spring. The anchor point, the detection mass of the outer mass unit 2, and the detection mass of the inner mass unit 1 can be configured based on the layout requirements of the substrate, and this application does not impose any restrictions on this.

[0114] In the above embodiment, the proof masses in the in-plane Y-axis direction include the proof masses provided on outer mass unit 2, the proof masses provided on inner mass unit 1, and the proof masses provided in the annular structure. The proof masses in the in-plane X-axis direction include the proof masses provided on outer mass unit 2 and the proof masses provided in the annular structure. This shared proof mass layout helps further enhance the sensitivity of the accelerometer within the same area, achieving higher space utilization.

[0115] For example, the X-axis single-degree-of-freedom spring and the Y-axis single-degree-of-freedom spring can be designed into different shapes according to the specific structure of the acceleration sensor to better enable the acceleration sensor to detect the in-plane Y-axis acceleration.

[0116] In this embodiment, the two first anchor points 31 are symmetrically distributed along the symmetry axis 100 . Example 3

[0117] This embodiment provides another acceleration sensor, the structure of which is substantially the same as that of the embodiment 2, and only the different parts are described below.

[0118] 13 to 18 , optionally, the X-axis single-degree-of-freedom spring is U-shaped; and the Y-axis single-degree-of-freedom spring is U-shaped.

[0119] In the above embodiment, both the X-axis single-degree-of-freedom spring and the Y-axis single-degree-of-freedom spring are U-shaped, which can weaken the cross-coupling caused by the asymmetry of the serpentine shape in the in-plane Y-axis detection mode of the acceleration sensor, thereby helping to improve the detection accuracy of the acceleration sensor.

[0120] 19 , optionally, the X-axis detection capacitor group 71 includes a first movable comb-tooth capacitor plate 715 provided on the outer mass unit 2 and a first fixed comb-tooth capacitor plate 714 fixed on the substrate;

[0121] The first movable comb-teeth capacitor plates 715 distributed along the in-plane X-axis direction and the first fixed comb-teeth capacitor plates 715 cooperate to form a first comb-teeth capacitor.

[0122] The first fixed comb-teeth capacitor plate 714 includes a plurality of sub-capacitor plates arranged in an array along the in-plane X-axis direction. The sub-capacitor plates of the first movable comb-teeth capacitor plate 715 are located between two adjacent sub-capacitor plates of the first fixed comb-teeth capacitor plate 714 .

[0123] It should be noted that when the outer mass unit 2 is displaced to the left by the acceleration along the in-plane X-axis, the capacitance distance between the sub-capacitor plates of the first movable comb-tooth capacitor plate 715 and the sub-capacitor plates of the first fixed comb-tooth capacitor plate 714 on one side of the fifth differential detection capacitor is reduced, and the capacitance distance between the sub-capacitor plates of the first movable comb-tooth capacitor plate 715 on the other side symmetrical along the Y-axis and the sub-capacitor plates of the first fixed comb-tooth capacitor plate 714 on that side is increased. The capacitance difference between the fifth differential detection capacitor and the sixth differential detection capacitor changes in proportion to the acceleration along the in-plane X-axis to the left. By detecting the change in the capacitance difference, the real-time value of the acceleration along the in-plane X-axis to the left can be obtained.

[0124] Similarly, when the outer mass unit 2 is displaced downward by the acceleration to the right along the in-plane X-axis, the real-time value of the acceleration to the right along the in-plane X-axis can also be obtained by detecting the change in the capacitance difference.

[0125] Optionally, the Y-axis detection capacitor group 72 includes a second movable comb-tooth capacitor plate 725 provided on the outer mass unit 2 and a second fixed comb-tooth capacitor plate 724 fixed on the substrate;

[0126] The second movable comb-tooth capacitor plates 725 distributed along the in-plane Y-axis direction and the second fixed comb-tooth capacitor plates cooperate to form a second comb-tooth capacitor 724 .

[0127] It should be noted that when the outer mass unit 2 is displaced upward by the acceleration along the Y-axis direction in the plane, the capacitance distance between the sub-capacitor plates of the second movable comb-tooth capacitor plate 725 and the sub-capacitor plates of the second fixed comb-tooth capacitor plate 724 on one side of it is reduced, and the capacitance distance between the sub-capacitor plates of the second movable comb-tooth capacitor plate 725 on the other side symmetrical along the X-axis and the sub-capacitor plates of the second fixed comb-tooth capacitor plate 724 on that side is increased. The seventh differential detection capacitor and the eighth differential detection capacitor undergo a capacitance difference change that is proportional to the acceleration along the Y-axis direction in the plane. By detecting the change in the capacitance difference, the real-time value of the acceleration along the Y-axis direction in the plane can be obtained.

[0128] Similarly, when the outer mass unit 2 is displaced downward by the acceleration along the in-plane Y-axis, the real-time value of the acceleration along the in-plane Y-axis can also be obtained by detecting the change in the capacitance difference.

[0129] In the above embodiment, the arrangement of the X-axis detection capacitor group 71 and the Y-axis detection capacitor group 72 is changed, so that the arrangement of the second acceleration detection unit is more flexible.

[0130] Optionally, the plurality of first fixed comb-tooth capacitor plates 714 are all fixed to the substrate via the second anchor point 32; the plurality of second fixed comb-tooth capacitor plates 724 are all fixed to the substrate via the third anchor point 33;

[0131] The second anchor point 32 and the third anchor point 33 are both close to the first anchor point 31 .

[0132] In the above embodiment, the arrangement of the X-axis detection capacitor group 71 and the Y-axis detection capacitor group 72 is changed, and the second anchor point 32 and the third anchor point 33 used to fix the X-axis detection capacitor group 71 and the Y-axis detection capacitor group 72 are also placed near the first anchor point 31 of the moving structure, so that all the X-axis detection capacitor groups 71, the Y-axis detection capacitor group 72, and the first anchor point 31 are located in the center of the acceleration sensor structure, further improving the acceleration sensor's ability to resist interference from factors such as stress, which helps to ensure the detection accuracy of the acceleration sensor.

[0133] It should be noted that the detection mode in the in-plane X-axis direction refers to the acceleration sensor being affected by the acceleration in the in-plane X-axis direction, see Figures 2, 8 and 14; the detection mode in the in-plane Y-axis direction refers to the acceleration sensor being affected by the acceleration in the in-plane Y-axis direction, see Figures 3, 9 and 15; the detection mode in the out-of-plane Z-axis direction refers to the acceleration sensor being affected by the acceleration in the out-of-plane Z-axis direction, see Figures 4, 10 and 16; the parasitic mode in the out-of-plane Z-axis direction refers to the acceleration sensor being affected by both the out-of-plane Z-axis acceleration and the Y-axis angular acceleration, see Figures 5, 11 and 17.

[0134] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An acceleration sensor, characterized in that, Comprising: A base and a first anchor point, the first anchor point being fixed to the middle of the base; An inner mass unit and an outer mass unit, the inner mass unit surrounding the outside of the first anchor point and elastically connected to the first anchor point, the outer mass unit surrounding the outside of the inner mass unit and elastically connected to the inner mass unit; A first seesaw unit and a second seesaw unit, the first seesaw unit and the second seesaw unit being oppositely arranged and enclosing a ring structure together; the ring structure surrounds the outside of the outer mass unit and is elastically connected to the outer mass unit; A first acceleration detection unit and a second acceleration detection unit, at least part of the first acceleration detection unit being arranged in the ring structure for detecting the acceleration along the out-of-plane Z-axis direction; The second acceleration detection unit is arranged on the outer mass unit for detecting the acceleration along the in-plane X-axis direction and the in-plane Y-axis direction; The out-of-plane Z-axis direction, the in-plane X-axis direction and the in-plane Y-axis direction are perpendicular to each other pairwise.

2. The acceleration sensor according to claim 1, wherein It further includes a first elastic member and a second elastic member; the extending direction of the first elastic member is perpendicular to the extending direction of the second elastic member; The inner mass unit is elastically connected to the first anchor point through the first elastic member; the outer mass unit is elastically connected to the inner mass unit through the second elastic member.

3. The acceleration sensor according to claim 2, characterized in that The first elastic member is an X-axis single-degree-of-freedom spring, and the second elastic member is a Y-axis single-degree-of-freedom spring; Or, the first elastic member is a Y-axis single-degree-of-freedom spring, and the second elastic member is an X-axis single-degree-of-freedom spring.

4. The acceleration sensor according to claim 3, wherein, The X-axis single-degree-of-freedom spring is serpentine and / or U-shaped; The Y-axis single-degree-of-freedom spring is serpentine and / or U-shaped.

5. The acceleration sensor according to claim 3, characterized in that The second acceleration detection unit includes an X-axis detection capacitor group and a Y-axis detection capacitor group arranged on the outer mass unit; The X-axis detection capacitor group is symmetrically arranged along the in-plane X-axis and symmetrically arranged along the in-plane Y-axis; the X-axis detection capacitor group is used for detecting the acceleration along the in-plane X-axis direction; The Y-axis detection capacitor group is symmetrically arranged along the in-plane Y-axis and symmetrically arranged along the in-plane X-axis; the Y-axis detection capacitor group is used for detecting the acceleration along the in-plane Y-axis direction.

6. The acceleration sensor according to claim 5, characterized in that, The X-axis detection capacitor group includes a movable capacitor plate arranged on the side wall of the outer mass unit, and a first fixed capacitor plate and a second fixed capacitor plate fixed on the base; wherein, the first fixed capacitor plate and the second fixed capacitor plate are parallel and spaced apart, and both the first fixed capacitor plate and the second fixed capacitor plate are distributed along the in-plane Y-axis direction; The first fixed capacitor plate and the second fixed capacitor plate are respectively arranged in a differential manner with the movable capacitor plate on the side wall of the outer mass unit.

7. The acceleration sensor according to claim 5, characterized in that, The X-axis detection capacitor group includes a first movable comb-shaped capacitor plate arranged on the outer mass unit and a first fixed comb-shaped capacitor plate fixed on the base; The first movable comb-shaped capacitor plate distributed along the in-plane X-axis direction and the first fixed comb-shaped capacitor plate cooperate to form a first comb-shaped capacitor.

8. The acceleration sensor according to claim 6, characterized in that, The Y-axis detection capacitor group includes a movable electrode disposed on the side wall of the outer mass unit, a third fixed capacitor plate fixed on the substrate, and a fourth fixed capacitor plate; wherein, the third fixed capacitor plate and the fourth fixed capacitor plate are parallel and spaced apart. The third fixed capacitor plate and the fourth fixed capacitor plate are respectively differentially disposed with the movable electrode on the side wall of the outer mass unit.

9. The acceleration sensor according to claim 7, wherein The Y-axis detection capacitor group includes a second movable comb-shaped capacitor plate disposed on the outer mass unit and a second fixed comb-shaped capacitor plate fixed on the substrate. The second movable comb-shaped capacitor plate and the second fixed comb-shaped capacitor plate distributed along the in-plane Y-axis direction cooperate to form a second comb capacitor.

10. The acceleration sensor according to claim 9, wherein The first fixed comb-shaped capacitor plate is fixed on the substrate through a second anchor point; the second fixed comb-shaped capacitor plate is fixed on the substrate through a third anchor point. Both the second anchor point and the third anchor point are close to the first anchor point.

11. The acceleration sensor according to claim 1, wherein The first seesaw unit is elastically connected to one end of the outer mass unit, and the second seesaw unit is elastically connected to the other end of the outer mass unit; the first seesaw unit and the second seesaw unit are symmetrically distributed along the symmetry axis of the acceleration sensor respectively; the first seesaw unit forms two first seesaw structures on both sides of the symmetry axis respectively, and both of the two first seesaw structures rotate along the first rotation axis; the second seesaw unit forms two second seesaw structures on both sides of the symmetry axis respectively, and both of the two second seesaw structures rotate along the second rotation axis; the first rotation axis and the second rotation axis are both distributed along the in-plane Y-axis direction, and the symmetry axis is distributed along the in-plane X-axis direction.

12. The acceleration sensor according to claim 1, characterized in that, It further includes a coupling beam. Part of the second seesaw unit is sleeved outside part of the first seesaw unit to form a nested structure, the coupling beam is located in the nested structure, and one end of the coupling beam is connected to the first seesaw unit and the other end is connected to the second seesaw unit.

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