Vibration rectification error correction circuit and sensor device

Abstract

A vibration rectification error correction circuit includes a signal processing portion that calculates a difference between a first signal value and a second signal value, the first signal value being a signal value of a physical quantity detected by a first sensor having a first detection axis, the second signal value being a signal value of the physical quantity detected by a second sensor having a second detection axis in an opposite direction to the first detection axis, the difference having a smaller vibration rectification error than the first signal value and a smaller vibration rectification error than the second signal value.

Description

Technical Field

[0001] This invention relates to a vibration rectification error correction circuit and a sensor device. Background Technology

[0002] Patent Document 1 describes a vibration rectification error correction circuit that obtains a digital value based on the measured signal output from a sensor element, and corrects the vibration rectification error of the digital value according to a correction function based on the product of values ​​obtained by biasing the digital value.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-191068 Summary of the Invention

[0004] The technical problem that the invention aims to solve

[0005] In the sensor device described in Patent Document 1, it is necessary to determine multiple coefficient values ​​of the correction function for vibration rectification error and construct an arithmetic circuit corresponding to the correction function.

[0006] Solutions for solving technical problems

[0007] One aspect of the vibration rectification error correction circuit involved in this invention includes: The signal processing unit calculates the difference between a first signal value and a second signal value, wherein the first signal value is a signal value of a physical quantity detected by a first sensor having a first detection axis, and the second signal value is a signal value of the physical quantity detected by a second sensor having a second detection axis in the opposite direction to the first detection axis. The vibration rectification error of the difference is smaller than the vibration rectification error of the first signal value and smaller than the vibration rectification error of the second signal value.

[0008] One aspect of the sensor device involved in this invention comprises: One method of the vibration rectification error correction circuit; The first sensor; and The second sensor. Attached Figure Description

[0009] Figure 1 This is a structural diagram of the sensor device.

[0010] Figure 2 This is an exploded 3D view of the sensor device.

[0011] Figure 3 This is a simplified structural diagram of the sensor device.

[0012] Figure 4 This is a simplified structural diagram of the sensor device.

[0013] Figure 5 This is a simplified structural diagram of the sensor.

[0014] Figure 6 This is a simplified structural diagram of the sensor element.

[0015] Figure 7 This is a functional block diagram of the sensor device according to the first embodiment.

[0016] Figure 8 This is a graph illustrating an example of the relationship between the frequency of the sensor and the amplitude of acceleration in the first embodiment.

[0017] Figure 9 This is a graph illustrating an example of the relationship between the frequency of the sensor and the amplitude of acceleration in the second embodiment.

[0018] Figure 10 This is another example of the relationship between the frequency of the sensor and the amplitude of acceleration in the second embodiment.

[0019] Explanation of reference numerals in the attached figures

[0020] 1: Sensor device; 2: Vibration rectification error correction circuit; 3: External device; 11: Container; 11a: Bottom; 11b: Side; 11c: Inner surface; 11d: Support surface; 13: Screw hole; 15: Opening; 17: Fixing protrusion; 19: Cover fixing screw hole; 21: Cover; 23: Through hole; 31: Circuit board; 33: Connector; 35: Processing circuit; 41: Cover fixing screw; 101: Sensor; 102: Sensor; 103: Sensor; 1 04: Sensor; 105: Sensor; 106: Sensor; 110: Package; 111: Storage space; 120: Package substrate; 120a: Inner side; 120b: Inner bottom surface; 120c: Stepped portion; 120d: Outer bottom surface; 130: Cover; 132: Cover mating component; 140: Internal terminal; 141: Conductive adhesive; 145: External terminal; 200: Sensor element; 201: Substrate structure; 210: Base; 212: Connector; 214 214a: Movable part; 214b: First main surface; 214b: Second main surface; 220: Connecting part; 225: Fixed part connecting terminal; 230: First support part; 240: Second support part; 250: Third support part; 260: Fourth support part; 270: Vibrating element; 271a: First vibrating beam part; 271b: Second vibrating beam part; 272a: First element base part; 272b: Second element base part; 280: Mass part; 280a: First mass part; 280b: Second mass part Measurement section; 301: Amplifier circuit; 302: Amplifier circuit; 303: Amplifier circuit; 304: Amplifier circuit; 305: Amplifier circuit; 306: Amplifier circuit; 311: Frequency ratio measurement circuit; 312: Frequency ratio measurement circuit; 313: Frequency ratio measurement circuit; 314: Frequency ratio measurement circuit; 315: Frequency ratio measurement circuit; 316: Frequency ratio measurement circuit; 320: Reference signal generation circuit; 330: Microcontroller unit; 340: Storage unit; 350: Interface circuit. Detailed Implementation

[0021] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the embodiments described below do not unduly limit the scope of the invention as defined in the claims. Furthermore, not all of the configurations described below are essential components of the present invention.

[0022] 1. First Implementation Method

[0023] 1-1. Structure of the sensor device

[0024] Figure 1 This is a diagram showing the external structure of sensor device 1. (See diagram for example.) Figure 1As shown, sensor device 1 is a cuboid with width W, depth D, and height H. Width W is the length along the long side of sensor device 1, depth D is the length along the short side of sensor device 1, and height H is the length along the side orthogonal to both the long and short sides.

[0025] Sensor device 1 is a device for measuring physical quantities. In the following description, we will take a device that measures acceleration as a physical quantity, specifically a device that measures acceleration along the X, Y, and Z axes, as an example. However, sensor device 1 can also measure physical quantities other than acceleration.

[0026] like Figure 1 As shown, the X-axis is the axis along the long side of sensor device 1. Figure 1 In this diagram, the +X direction is from left to right along the long side of sensor device 1, and the -X direction is from right to left along the long side of sensor device 1. The Y-axis is the axis along the short side of sensor device 1. Figure 1 In this diagram, the +Y direction is from the front of the short side of sensor device 1 towards the inward side, and the -Y direction is from the inward side of the short side of sensor device 1 towards the front. The Z-axis is the axis along the side orthogonal to the long and short sides of sensor device 1. Figure 1 In the diagram, the +Z direction is from the bottom of sensor device 1 to the top, and the -Z direction is from the top of sensor device 1 to the bottom.

[0027] like Figure 1 As shown, the sensor device 1 includes a container 11 and a cover 21. The container 11 houses the circuit board 31, which will be described later. The container 11 is a box-shaped body with an opening in the -Z direction. The container 11 forms part of the outer packaging shell of the sensor device 1 and is made of a metal material such as aluminum. The container 11 has a bottom 11a and a side 11b. The bottom 11a is flat and has three screw holes 13 and an opening 15. The side 11b is a frame-shaped member extending from the outer periphery of the bottom 11a in the -Z direction.

[0028] Three screw holes 13 are provided at the two corners and the center of the long side of the sensor device 1. Fixing screws (not shown) are inserted into the screw holes 13. The sensor device 1 is fixed to the mounting surface of the object being mounted using these screws. The sensor device 1 is used with or without being directly or indirectly fixed to the mounting surface of the object being mounted. The object being mounted can be a building, bridge, machinery, or other structure. It can also be a mobile object such as a car, drone, robot, or ship.

[0029] The connector 33, described later, is inserted into the opening 15. The connector 33 is disposed on the circuit board 31 housed in the container 11.

[0030] The lid 21 is fitted onto the container 11 at a position in the -Z direction and covers the opening of the container 11 in the -Z direction. The lid 21 can be fitted onto the container 11 directly or via a sealing member not shown.

[0031] Figure 2 This is an exploded perspective view of sensor device 1, showing the state when sensor device 1 is disassembled. Sensor device 1 is disassembled into container 11, cover 21, and circuit board 31.

[0032] The container 11 has: a bottom 11a with an opening 15; and a side 11b with an inner surface 11c and a support surface 11d. The inner surface 11c is the inner circumferential surface of the side 11b. The support surface 11d is the end face of the side 11b in the -Z direction, which is opposite to the cover 21 and supports the cover 21.

[0033] like Figure 2 As shown, three fixing protrusions 17 protruding from the support surface 11d in the -Z direction are provided on the support surface 11d of the container 11. Screw holes 13 are formed in each of the three fixing protrusions 17. Additionally, three cover fixing screw holes 19 are provided on the support surface 11d of the container 11 at the corners and the center of the long side of the container 11. Cover fixing screws 41 are inserted into the cover fixing screw holes 19.

[0034] Three through holes 23 are formed in the lid portion 21. When the lid portion 21 is assembled to the container 11, the through holes 23 are formed at positions corresponding to the lid fixing screw holes 19. The lid fixing screws 41 are inserted into the three through holes 23 respectively. The lid portion 21 is assembled to the container 11 by the lid fixing screws 41.

[0035] The circuit board 31 is housed in the container 11. The circuit board 31 is a multilayer substrate for forming multiple through holes, etc. The circuit board 31 is made of, for example, a glass epoxy board. However, the circuit board 31 may also be made of a composite substrate, a ceramic substrate, etc.

[0036] Figure 3 and Figure 4 This is a diagram showing a simplified structure of sensor device 1. Figure 3 This is an X-Z cross-sectional view along approximately the center of the Y-axis of sensor device 1. Figure 4 This is a three-dimensional view of the circuit board 31.

[0037] like Figure 3 and Figure 4 As shown, the circuit board 31 has a first surface S1 and a second surface S2. The first surface S1 is the surface of the circuit board 31 in the -Z direction, and the second surface S2 is the surface of the circuit board 31 in the +Z direction. The circuit board 31 is in contact with the container 11 through the second surface S2 and is supported by the container 11.

[0038] Sensors 101, 102, 103, 104, and 106 are mounted on the first surface S1 of the circuit board 31. A connector 33, a processing circuit 35, and a sensor 105 are mounted on the second surface S2 of the circuit board 31. Six amplifier circuits (not shown) 301 to 306, which are respectively connected to the six sensors 101 to 106, are mounted on the circuit board 31.

[0039] Six oscillation circuits are formed by each of the six sensors 101 to 106 and each of the six amplifier circuits 301 to 306. The processing circuit 35 is input with the six oscillation signals output from the six oscillation circuits and calculates triaxial acceleration data based on the frequencies of the six oscillation signals.

[0040] Connector 33 connects to an external device, from which a drive voltage is input to connector 33, while connector 33 outputs various signals to the external device. Connector 33 is a plug with multiple pins, and the external device has a socket for connection to the plug. Sensors 101-106, amplifier circuits 301-306, processing circuit 35, and connector 33 are electrically connected via wiring (not shown).

[0041] Sensors 101 and 102 are arranged opposite to each other. Sensors 103 and 104 are arranged opposite to each other. Sensors 105 and 106 are arranged opposite to each other across the circuit board 31.

[0042] Sensor 101 has a detection axis D1 in the +X direction and detects acceleration in the +X direction. Sensor 102 has a detection axis D2 in the -X direction and detects acceleration in the -X direction. Detection axis D2 is in the opposite direction to detection axis D1.

[0043] Sensor 103 has a detection axis D3 in the +Y direction and detects acceleration in the +Y direction. Sensor 104 has a detection axis D4 in the -Y direction and detects acceleration in the -Y direction. Detection axis D4 is in the opposite direction to detection axis D3.

[0044] Sensor 105 has a detection axis D5 in the +Z direction and detects acceleration in the +Z direction. Sensor 106 has a detection axis D6 in the -Z direction and detects acceleration in the -Z direction. Detection axis D6 is in the opposite direction to detection axis D5.

[0045] 1-2. Sensor Structure

[0046] Figure 5 This is a diagram showing a simplified structure of sensor 101, and schematically showing a cross-section of sensor 101.

[0047] exist Figure 5In this diagram, axes A and B are parallel to the plane of the flat substrate structure 201 (described later), and are orthogonal to each other. A axis is orthogonal to the direction in which the vibrating element 270 extends (described later). The +A direction is from the inside of sensor 101 towards the front, and the -A direction is from the front of sensor 101 towards the inside. B axis is parallel to the direction in which the vibrating element 270 extends. The +B direction is from right to left of sensor 101, and the -B direction is from left to right of sensor 101. C axis is orthogonal to axes A and B. The +C direction is from bottom to top of sensor 101, and the -C direction is from top to bottom of sensor 101.

[0048] The sensor 101 has a sensor element 200 and a package 110, wherein the sensor element 200 is housed in a storage space 111 formed by the package 110.

[0049] Package 110 is a housing that defines the storage space 111 and has a package base 120 and a cover 130. The storage space 111 is covered by the package base 120 and the cover 130.

[0050] The package base 120 is a box-shaped body with an opening in the +C direction, and has an inner surface 120a, an inner bottom surface 120b, a stepped portion 120c, and an outer bottom surface 120d. The inner surface 120a and the inner bottom surface 120b are the interior surfaces of the package base 120. The outer bottom surface 120d is the outer surface of the package base 120. The package base 120 has external terminals 145.

[0051] The stepped portion 120c is a portion that protrudes from the inner bottom surface 120b of the package base 120 in the +C direction, and is frame-shaped along the inner side surface 120a. A plurality of internal terminals 140 are provided in the stepped portion 120c.

[0052] Multiple internal terminals 140 are connected to fixing portion connection terminals 225 respectively provided on the first support portion 230, second support portion 240, third support portion 250 and fourth support portion 260 of the sensor element 200, as described later. The internal terminals 140 and fixing portion connection terminals 225 are electrically and mechanically connected via conductive adhesive 141.

[0053] External terminals 145 are disposed on the outer bottom surface 120d and are electrically connected to internal terminals 140 via internal wiring (not shown). External terminals 145 are electrically connected to sensor 101 via wiring disposed on circuit board 31. External terminals 145 may also be disposed on the outer surface of package substrate 120, which is different from the outer bottom surface 120d.

[0054] The cover 130 is a flat plate that blocks the opening of the package base 120. The cover 130 is fitted to the package base 120 via the cover engagement member 132. By blocking the opening of the package base 120 with the cover 130, the storage space 111 for housing the sensor element 200 is hermetically sealed.

[0055] Figure 6 This is a diagram showing a simplified structure of the sensor element 200. Figure 6 The sensor element 200 is shown in a perspective view. The sensor element 200 has a substrate structure 201, a vibration element 270, and a mass part 280.

[0056] The substrate structure 201 is a flat plate with a main surface parallel to the A-B plane, and includes a base 210, a movable part 214, a connecting part 220, a first support part 230, a second support part 240, a third support part 250, and a fourth support part 260. The substrate structure 201 is made of, for example, a crystal substrate. However, the substrate structure 201 may also be made of a material other than crystal.

[0057] The base 210 is connected to the movable part 214 via a groove-shaped joint 212 along the A-axis, supporting the movable part 214 so that it can swing. When viewed from the +C direction, the base 210 is a U-shaped part bent at a right angle. In the +B direction of the movable part 214, the connecting part 220 connects the two ends of the U-shape formed by the base 210 along the A-axis. Thus, the base 210 and the connecting part 220 are approximately frame-shaped when viewed from above. The first support part 230 and the second support part 240 are connected in the +A and -A directions of the base 210. The third support part 250 and the fourth support part 260 are connected near the connecting part 220 of the base 210.

[0058] A connector 212 is disposed between the base 210 and the movable part 214, connecting the base 210 and the movable part 214. The thickness of the connector 212 along the C-axis is thinner than the thickness of the base 210 along the C-axis and the thickness of the movable part 214 along the C-axis. When viewed from the +A direction, the connector 212 is formed into a necked shape on both sides along the C-axis, and functions as a fulcrum when the movable part 214 is displaced relative to the base 210.

[0059] The movable part 214 is connected to the base 210 via the joint 212. The movable part 214 is flat and has a first main surface 214a and a second main surface 214b. The first main surface 214a is the surface of the movable part 214 in the +C direction, and the second main surface 214b is the surface of the movable part 214 in the -C direction. The first main surface 214a and the second main surface 214b are in a front-back relationship. The movable part 214 is displaced along the C-axis with the joint 212 as the fulcrum according to the acceleration along the C-axis. That is, the joint 212 and the movable part 214 function as a cantilever that deforms due to the applied acceleration along the C-axis.

[0060] The first support portion 230 is an arm-shaped portion bent at right angles along the A-axis and B-axis, and is positioned in the +A direction and -B direction of the sensor element 200. The second support portion 240 is an arm-shaped portion bent at right angles along the A-axis and B-axis, and is positioned in the -A direction and -B direction of the sensor element 200. When viewed from above in the +C direction, the first support portion 230 and the second support portion 240 are symmetrically arranged with respect to the centerline of the vibration element 270 along the B-axis.

[0061] The third support portion 250 is an arm-shaped section bent at right angles along axes A and B, and is positioned in the +A and +B directions of the sensor element 200. The fourth support portion 260 is also an arm-shaped section bent at right angles along axes A and B, and is positioned in the -A and +B directions of the sensor element 200. When viewed from above in the +C direction, the third support portion 250 and the fourth support portion 260 are symmetrically arranged with respect to the centerline of the vibration element 270 along the B-axis.

[0062] The distal ends of the first support portion 230, the second support portion 240, the third support portion 250, and the fourth support portion 260 are connected to the stepped portion 120c of the package 110. The first support portion 230, the second support portion 240, the third support portion 250, and the fourth support portion 260 support the base portion 210 within the receiving space 111.

[0063] The two ends of the vibrating element 270 along the B-axis are connected to the base 210 and the movable part 214 of the substrate structure 201. The vibrating element 270 is disposed on the base 210 and the movable part 214 in a manner that spans the joint part 212.

[0064] The vibrating element 270 is formed, for example, from a crystal substrate. However, the vibrating element 270 may also be formed from a piezoelectric material other than crystal. Preferably, the vibrating element 270 and the substrate structure 201 are formed from the same material. By making the vibrating element 270 and the substrate structure 201 from the same material, the difference between the coefficient of linear expansion of the substrate structure 201 and the coefficient of linear expansion of the vibrating element 270 is reduced, which can suppress the stress applied to the vibrating element 270 from the substrate structure 201 due to the difference in the coefficient of linear expansion.

[0065] Vibrating element 270 is, for example, a double tuning fork type vibrating element. Vibrating element 270 has a first vibrating beam portion 271a, a second vibrating beam portion 271b, a first element base portion 272a, and a second element base portion 272b. The first vibrating beam portion 271a and the second vibrating beam portion 271b extend along the B-axis. The first element base portion 272a is connected to the ends of the first vibrating beam portion 271a and the second vibrating beam portion 271b in the +B direction. The first element base portion 272a is connected to the movable portion 214. The second element base portion 272b is connected to the ends of the first vibrating beam portion 271a and the second vibrating beam portion 271b in the -B direction. The second element base portion 272b is connected to the base 210 of the substrate structure 201. It should be noted that vibrating element 270 is not limited to a double tuning fork type vibrating element; for example, it can also be a single-span beam type vibrating element with a single vibrating beam portion.

[0066] The vibrating element 270 has excitation electrodes (not shown) disposed on its surface. When an AC voltage drive signal is applied to the excitation electrodes disposed on the vibrating element 270, the first vibrating beam portion 271a and the second vibrating beam portion 271b undergo bending vibrations that are either separated from or close to each other along the A-axis. That is, the vibrating element 270 functions as a resonator.

[0067] The sensor element 200 has a plurality of mass portions 280. A first mass portion 280a of the plurality of mass portions 280 is disposed on a first main surface 214a of a movable portion 214. Two of these first mass portions 280a are disposed on the first main surface 214a. The first mass portions 280a are joined to the first main surface 214a via a bonding material (not shown). A second mass portion 280b of the plurality of mass portions 280 is disposed on a second main surface 214b of the movable portion 214. Two of these second mass portions 280b are disposed on the second main surface 214b. The second mass portions 280b are joined to the second main surface 214b via a bonding material (not shown). The mass portions 280 are made of metals such as copper or gold. The number of mass portions 280 may also be one.

[0068] When an acceleration in the +C direction is applied to the sensor element 200, the movable part 214 displaces in the -C direction with the joint part 212 as the fulcrum. As the movable part 214 displaces in the -C direction, forces are applied to the first element base 272a and the second element base 272b in directions that are mutually distancing along the B-axis, generating tensile stress in the first vibration beam 271a and the second vibration beam 271b. The resonant frequencies of the first vibration beam 271a and the second vibration beam 271b increase due to the tensile stress.

[0069] When an acceleration in the -C direction is applied to the sensor element 200, the movable part 214 displaces in the +C direction with the joint part 212 as the fulcrum. As the movable part 214 displaces in the +C direction, a force is applied to the first element base 272a and the second element base 272b along the direction that brings them closer together on the B-axis, generating compressive stress in the first vibration beam 271a and the second vibration beam 271b. The resonant frequency of the first vibration beam 271a and the second vibration beam 271b decreases due to the compressive stress.

[0070] Sensor element 200 can detect acceleration in the +C and -C directions based on the resonant frequency of vibration element 270. Since acceleration in the +C direction is considered positive, acceleration in the -C direction is equivalent to negative acceleration in the +C direction. Therefore, it can be said that sensor element 200 detects both positive and negative acceleration in the +C direction. In other words, sensor element 200 is a frequency-varying acceleration sensor element with a detection axis in the +C direction that detects acceleration in the +C direction.

[0071] In the sensor element 200 included in the sensor 101, when a drive signal is applied to the electrodes via the external terminal 145, the internal terminal 140, the fixing connection terminal 225, etc., the first vibration beam 271a and the second vibration beam 271b will resonate at a predetermined frequency. The sensor 101 outputs an output signal based on the resonant frequency of the sensor element 200, which changes according to the acceleration. That is, the sensor 101 is a frequency-varying acceleration sensor with the detection axis as the C-axis.

[0072] It should be noted that since the structure of sensors 102-106 is the same as that of sensor 101, their illustrations and descriptions are omitted. Sensor 101 detects acceleration in the +X direction by means of a detection axis configured in the +C direction along the +X direction. Sensor 102 detects acceleration in the -X direction by means of a detection axis configured in the +C direction along the -X direction. Sensor 103 detects acceleration in the +Y direction by means of a detection axis configured in the +C direction along the +Y direction. Sensor 104 detects acceleration in the -Y direction by means of a detection axis configured in the +C direction along the -Y direction. Sensor 105 detects acceleration in the +Z direction by means of a detection axis configured in the +C direction along the +Z direction. Sensor 106 detects acceleration in the -Z direction by means of a detection axis configured in the +C direction along the -Z direction.

[0073] 1-3. Functional Structure of Sensor Devices

[0074] Figure 7 This is a functional block diagram of the sensor device 1 according to the first embodiment. As described above, the sensor device 1 includes the aforementioned sensors 101 to 106 and the vibration rectification error correction circuit 2.

[0075] As previously described, sensor 101 has a detection axis D1 and detects acceleration in the +X direction. Sensor 102 has a detection axis D2 with a direction opposite to detection axis D1 and detects acceleration in the -X direction. Sensor 103 has a detection axis D3 and detects acceleration in the +Y direction. Sensor 104 has a detection axis D4 with a direction opposite to detection axis D3 and detects acceleration in the -Y direction. Sensor 105 has a detection axis D5 and detects acceleration in the +Z direction. Sensor 106 has a detection axis D6 with a direction opposite to detection axis D5 and detects acceleration in the -Z direction.

[0076] The vibration rectification error correction circuit 2 includes the aforementioned amplifier circuits 301 to 306 and the aforementioned processing circuit 35.

[0077] Amplifier circuit 301 amplifies the output signal of sensor 101 and generates a drive signal, which is then applied to sensor 101. Driven by this drive signal, the vibration element 270 of sensor 101 vibrates at a frequency corresponding to the acceleration in the +X direction, and a signal at this frequency is output by sensor 101. Additionally, amplifier circuit 301 outputs the rectangular wave signal obtained by amplifying the output signal of sensor 101, i.e., the measured signal SIN_XP, to frequency ratio measurement circuit 311.

[0078] Amplification circuit 302 amplifies the output signal of sensor 102 and generates a drive signal, which is then applied to sensor 102. Driven by this drive signal, the vibration element 270 of sensor 102 vibrates at a frequency corresponding to the acceleration in the -X direction, and a signal at this frequency is output by sensor 102. Additionally, amplification circuit 302 outputs the rectangular wave signal obtained by amplifying the output signal of sensor 102, i.e., the measured signal SIN_XN, to frequency ratio measurement circuit 312.

[0079] Amplifier circuit 303 amplifies the output signal of sensor 103 and generates a drive signal, which is then applied to sensor 103. Driven by this drive signal, the vibration element 270 of sensor 103 vibrates at a frequency corresponding to the acceleration in the +Y direction, and a signal at this frequency is output by sensor 103. Additionally, amplifier circuit 303 outputs the rectangular wave signal obtained by amplifying the output signal of sensor 103, i.e., the measured signal SIN_YP, to frequency ratio measurement circuit 313.

[0080] Amplifier circuit 304 amplifies the output signal of sensor 104 and generates a drive signal, which is then applied to sensor 104. Driven by this drive signal, the vibration element 270 of sensor 104 vibrates at a frequency corresponding to the acceleration in the -Y direction, and a signal at this frequency is output by sensor 104. Additionally, amplifier circuit 304 outputs the rectangular wave signal obtained by amplifying the output signal of sensor 104, i.e., the measured signal SIN_YN, to frequency ratio measurement circuit 314.

[0081] Amplifier circuit 305 amplifies the output signal of sensor 105 and generates a drive signal, which is then applied to sensor 105. Driven by this drive signal, the vibration element 270 of sensor 105 vibrates at a frequency corresponding to the acceleration in the +Z direction, and a signal at this frequency is output by sensor 105. Additionally, amplifier circuit 305 outputs the rectangular wave signal obtained by amplifying the output signal of sensor 105, i.e., the measured signal SIN_ZP, to frequency ratio measurement circuit 315.

[0082] Amplifier circuit 306 amplifies the output signal of sensor 106 and generates a drive signal, which is then applied to sensor 106. Driven by this drive signal, the vibration element 270 of sensor 106 vibrates at a frequency corresponding to the acceleration in the -Z direction, and a signal at this frequency is output by sensor 106. Additionally, amplifier circuit 306 outputs the rectangular wave signal obtained by amplifying the output signal of sensor 106, i.e., the measured signal SIN_ZN, to frequency ratio measurement circuit 316.

[0083] The processing circuit 35 includes frequency ratio measurement circuits 311-316, a reference signal generation circuit 320, a microcontroller unit 330, a storage unit 340, and an interface circuit 350.

[0084] The reference signal generation circuit 320 generates and outputs a reference signal CLK of a certain frequency. Preferably, the reference signal CLK has high frequency accuracy, and the reference signal generation circuit 320 can be, for example, a temperature-compensated crystal oscillator.

[0085] The frequency ratio measurement circuit 311 counts the number of pulses of the reference signal CLK included in a predetermined period of the measured signal SIN_XP output from the amplifier circuit 301, and outputs a count value CNT_XP. The count value CNT_XP is the count value corresponding to the frequency ratio of the measured signal SIN_XP to the reference signal CLK.

[0086] The frequency ratio measurement circuit 312 counts the number of pulses of the reference signal CLK included in a predetermined period of the measured signal SIN_XN output from the amplifier circuit 302, and outputs a count value CNT_XN. The count value CNT_XN is the count value corresponding to the frequency ratio of the measured signal SIN_XN to the reference signal CLK.

[0087] The frequency ratio measurement circuit 313 counts the number of pulses of the reference signal CLK included in a predetermined period of the measured signal SIN_YP output from the amplifier circuit 303, and outputs a count value CNT_YP. The count value CNT_YP is the count value corresponding to the frequency ratio of the measured signal SIN_YP to the reference signal CLK.

[0088] The frequency ratio measurement circuit 314 counts the number of pulses of the reference signal CLK included in a predetermined period of the measured signal SIN_YN output from the amplifier circuit 304, and outputs a count value CNT_YN. The count value CNT_YN is the count value corresponding to the frequency ratio of the measured signal SIN_YN to the reference signal CLK.

[0089] The frequency ratio measurement circuit 315 counts the number of pulses of the reference signal CLK included in a predetermined period of the measured signal SIN_ZP output from the amplifier circuit 305, and outputs a count value CNT_ZP. The count value CNT_ZP is the count value corresponding to the frequency ratio of the measured signal SIN_ZP to the reference signal CLK.

[0090] The frequency ratio measurement circuit 316 counts the number of pulses of the reference signal CLK included in a predetermined period of the measured signal SIN_ZN output from the amplifier circuit 306, and outputs a count value CNT_ZN. The count value CNT_ZN is the count value corresponding to the frequency ratio of the measured signal SIN_ZN to the reference signal CLK.

[0091] Storage unit 340 is a memory that stores programs and data, and may also include volatile memory such as SRAM and DRAM. SRAM is an abbreviation for Static Random Access Memory, and DRAM is an abbreviation for Dynamic Random Access Memory. Alternatively, storage unit 340 may also include non-volatile memory such as semiconductor memory like EEPROM, magnetic storage devices like hard disk drives, and optical storage devices like optical disc drives. EEPROM is an abbreviation for Electrically Erasable Programmable Read Only Memory.

[0092] The microcontroller unit 330 operates synchronously with the reference signal CLK and performs predetermined computational and control processing by executing a program (not shown) stored in the storage unit 340. For example, the microcontroller unit 330 measures acceleration on the X-axis based on the count value CNT_XP output from the frequency ratio measurement circuit 311 and the count value CNT_XN output from the frequency ratio measurement circuit 312. Furthermore, the microcontroller unit 330 measures acceleration on the Y-axis based on the count value CNT_YP output from the frequency ratio measurement circuit 313 and the count value CNT_YN output from the frequency ratio measurement circuit 314. Additionally, the microcontroller unit 330 measures acceleration on the Y-axis based on the count value CNT_ZP output from the frequency ratio measurement circuit 315 and the count value CNT_ZN output from the frequency ratio measurement circuit 316. Measurement Acceleration on the Z-axis.

[0093] Specifically, the microcontroller unit 330 converts the count values ​​CNT_XP and CNT_XN into acceleration values ​​in the +X direction and the -X direction, respectively. The acceleration value in the +X direction is based on the acceleration signal value detected by sensor 101, and the acceleration value in the -X direction is based on the acceleration signal value detected by sensor 102. Furthermore, the microcontroller unit 330 calculates the difference between the acceleration values ​​in the +X direction and the acceleration values ​​in the -X direction as the acceleration value along the X-axis.

[0094] Similarly, the microcontroller 330 converts the count values ​​CNT_YP and CNT_YN into acceleration values ​​in the +Y direction and -Y direction, respectively. The acceleration value in the +Y direction is based on the acceleration signal value detected by sensor 103, and the acceleration value in the -Y direction is based on the acceleration signal value detected by sensor 104. Furthermore, the microcontroller 330 calculates the difference between the acceleration values ​​in the +Y direction and the acceleration values ​​in the -Y direction as the acceleration value along the Y-axis.

[0095] Similarly, the microcontroller 330 converts the count values ​​CNT_ZP and CNT_ZN into acceleration values ​​in the +Z direction and -Z direction, respectively. The acceleration value in the +Z direction is based on the acceleration signal value detected by sensor 105, and the acceleration value in the -Z direction is based on the acceleration signal value detected by sensor 106. Furthermore, the microcontroller 330 calculates the difference between the acceleration values ​​in the +Z direction and the acceleration values ​​in the -Z direction as the acceleration value along the Z-axis.

[0096] For example, the storage unit 340 may store table information that specifies the correspondence between count values ​​and acceleration values ​​or information on the relationship between count values ​​and acceleration values, and the microcontroller unit 330 may refer to this information to convert each count value into an acceleration value.

[0097] Alternatively, the microcontroller 330 can generate measurement data including the calculated acceleration values ​​of the X-axis, Y-axis, and Z-axis, and send the measurement data to the external device 3 via the interface circuit 350. Alternatively, the microcontroller 330 can write the measurement data to the storage unit 340, and the external device 3 can read the measurement data via the interface circuit 350.

[0098] 1-4. Vibration Rectification Error Correction

[0099] The frequency Y1 of the output signal of sensor 101 varies according to the magnitude of the acceleration in the +X direction. Considering the nonlinearity of the sensor 101's sensitivity with a quadratic coefficient, the relationship between the input acceleration X in the +X direction and the frequency Y1 can be expressed by equation (1). In equation (1), Y... 1（0G） A1 is the frequency when the acceleration X is 0G, B1 is the second-order sensitivity coefficient, and B1 is the first-order sensitivity coefficient.

[0100]

Number 1

[0101] According to the quadratic term in equation (1), the output frequency Y1 is generated, which is equivalent to the nonlinearity of the acceleration X, and due to this nonlinearity, a vibration rectification error (VRE) is generated.

[0102] The vibration rectification error is calculated as follows. When a sinusoidal vibration is input, i.e., acceleration X = X... 1･ When cos(ωt), according to equation (1), the frequency Y1 can be expressed by equation (2).

[0103]

Number 2

[0104] According to equation (2), the time average value of acceleration Y over the time period T (2Nπ / ω) from time 0 to N is... 1.AVE It can be represented by equation (3).

[0105]

Number 3

[0106] If we integrate cos(ωt) over N periods, then cos(ωt)≈0, and thus equation (4) can be obtained from equation (3).

[0107]

Number 4

[0108] Therefore, the vibration rectification error VRE1 of the acceleration value in the +X direction can be expressed by equation (5).

[0109]

Number 5

[0110] Furthermore, since sensor 102 is assembled in the direction opposite to sensor 101, the frequency Y2 changes according to the magnitude of the acceleration in the -X direction. Therefore, the positive and negative values ​​of the acceleration X input to sensor 101 and sensor 102 are reversed. Thus, the relationship between the acceleration -X = -X1·cos(ωt) input to sensor 102 in the -X direction and the frequency Y2 can be expressed by equation (6). In equation (6), Y... 2（0G） A1 is the frequency when the acceleration X is 0G, A2 is the second-order sensitivity coefficient, and B2 is the first-order sensitivity coefficient.

[0111]

Number 6

[0112] Therefore, the vibration rectification error VRE2 of the acceleration value in the -X direction can be expressed by equation (7).

[0113]

Number 7

[0114] In contrast, according to equations (2) and (6), the frequency Y obtained by subtracting frequency Y2 from frequency Y1 is... 1－2 It can be expressed by equation (8).

[0115]

Number 8

[0116] As mentioned earlier, sensors 101 and 102 have the following structures: the cantilever deforms when accelerated, and the frequency of vibration of the vibrating element 270 changes due to the stress generated by the cantilever deformation. Because of its integrated structure with the cantilever, the individual differences in the quadratic coefficients of the sensitivity are small, and the vibrating element 270 is a crystal vibrating element with high frequency stability; therefore, the difference between the quadratic coefficients A1 and A2 is very small. Therefore, the frequency Y... 1－2 The quadratic coefficient (A1-A2) is close to 0.

[0117] Figure 8 The frequency Y1, Y2, Y is shown in the figure. 1－2 An example of the relationship between the amplitude X1 of the acceleration. Figure 8 In the diagram, the dashed lines represent the ideal straight lines when the quadratic terms of equations (2), (5), and (8) are set to 0. For example... Figure 8 As shown, frequency Y 1－2 Compared to frequencies Y1 and Y2, it is closer to an ideal straight line. It should be noted that the first-order coefficient (B1 + B2) in equation (8) represents the frequency Y. 1－2 Regarding the sensitivity relative to acceleration X, since B1≈B2, therefore, the frequency Y... 1－2 Its sensitivity is approximately twice that of frequencies Y1 and Y2.

[0118] Similarly, if we derive the vibration rectification error VRE1 of the acceleration value in the +X direction according to equation (2) and express it in equation (5), then the vibration rectification error VRE1 of the difference between the acceleration value in the +X direction and the acceleration value in the -X direction according to equation (8) can also be derived. 1－2 Then we can obtain equation (9).

[0119]

Number 9

[0120] Since the difference between the quadratic coefficients A1 and A2 is very small, the vibration rectification error VRE, expressed by equation (9), is the difference between the acceleration values ​​in the +X direction and the acceleration values ​​in the -X direction. 1－2 It is smaller than the vibration rectification error VRE1 of the acceleration value in the +X direction expressed by equation (5) and the vibration rectification error VRE2 of the acceleration value in the -X direction expressed by equation (7).

[0121] Although the explanation is omitted, since sensors 103-106 have the same structure as sensors 101 and 102, the vibration rectification error of the difference between the acceleration values ​​in the +Y direction and the -Y direction is smaller than the vibration rectification errors of the acceleration values ​​in the +Y direction and the -Y direction. Similarly, the vibration rectification error of the difference between the acceleration values ​​in the +Z direction and the -Z direction is smaller than the vibration rectification errors of the acceleration values ​​in the +Z direction and the -Z direction.

[0122] Thus, the vibration rectification error of the difference between the acceleration values ​​in the +X direction and the -X direction, calculated by the microcontroller 330 as the acceleration value of the X-axis, is smaller than the vibration rectification error of the acceleration value in the +X direction and smaller than the vibration rectification error of the acceleration value in the -X direction. Similarly, the vibration rectification error of the difference between the acceleration values ​​in the +Y direction and the -Y direction, calculated by the microcontroller 330 as the acceleration value of the Y-axis, is smaller than the vibration rectification error of the acceleration value in the +Y direction and smaller than the vibration rectification error of the acceleration value in the -Y direction. Likewise, the vibration rectification error of the difference between the acceleration values ​​in the +Z direction and the -Z direction, calculated by the microcontroller 330 as the acceleration value of the Z-axis, is smaller than the vibration rectification error of the acceleration value in the +Z direction and smaller than the vibration rectification error of the acceleration value in the -Z direction.

[0123] It should be noted that in the first embodiment, sensor 101 is an example of a "first sensor," and sensor 102 is an example of a "second sensor." Furthermore, sensor 103 is another example of a "first sensor," and sensor 104 is another example of a "second sensor." Additionally, sensor 105 is another example of a "first sensor," and sensor 106 is another example of a "second sensor." The detection axis D1 of sensor 101 is an example of a "first detection axis," and the detection axis D2 of sensor 102 is an example of a "second detection axis." Furthermore, the detection axis D3 of sensor 103 is another example of a "first detection axis," and the detection axis D4 of sensor 104 is another example of a "second detection axis." Additionally, the detection axis D5 of sensor 105 is another example of a "first detection axis," and the detection axis D6 of sensor 106 is another example of a "second detection axis." The microcontroller unit 330 is an example of a "signal processing unit." The acceleration value in the +X direction calculated by the microcontroller 330 is an example of a "first signal value," and the acceleration value in the -X direction calculated by the microcontroller 330 is an example of a "second signal value." Similarly, the acceleration value in the +Y direction calculated by the microcontroller 330 is another example of a "first signal value," and the acceleration value in the -Y direction calculated by the microcontroller 330 is another example of a "second signal value." Furthermore, the acceleration value in the +Z direction calculated by the microcontroller 330 is another example of a "first signal value," and the acceleration value in the -Z direction calculated by the microcontroller 330 is another example of a "second signal value."

[0124] 1-5. Effects

[0125] As explained above, in the sensor device 1 of the first embodiment, in the vibration rectification error correction circuit 2, vibration rectification errors occur in the acceleration values ​​calculated by the microcontroller 330, specifically the even-order components of the acceleration values ​​in the +X, +Y, +Z, -X, -Y, and -Z directions. In contrast, in the vibration rectification error correction circuit 2, the microcontroller 330 calculates the differences between the +X and -X, +Y and -Y, and +Z and -Z direction acceleration values, thus reducing the even-order components of the X-axis, Y-axis, and Z-axis accelerations. Therefore, according to the sensor device 1 of the first embodiment, the vibration rectification error can be reduced in the vibration rectification error correction circuit 2 through simple calculations by the microcontroller 330.

[0126] Furthermore, in the sensor device 1 of the first embodiment, in the vibration rectification error correction circuit 2, the detection axis directions of sensors 101 and 102 are opposite, the detection axis directions of sensors 103 and 104 are opposite, and the detection axis directions of sensors 105 and 106 are opposite. Therefore, the values ​​of the primary components of acceleration included in the +X direction acceleration value and the -X direction acceleration value calculated by the microcontroller 330 are opposite in sign, the values ​​of the primary components of acceleration included in the +Y direction acceleration value and the -Y direction acceleration value are opposite in sign, and the values ​​of the primary components of acceleration included in the +Z direction acceleration value and the -Z direction acceleration value are opposite in sign. Therefore, according to the sensor device 1 of the first embodiment, in the vibration rectification error correction circuit 2, the difference between the acceleration value in the +X direction and the acceleration value in the -X direction, the difference between the acceleration value in the +Y direction and the acceleration value in the -Y direction, and the difference between the acceleration value in the +Z direction and the acceleration value in the -Z direction are calculated by the microcontroller unit 330. The values ​​of the primary components of the X-axis acceleration, Y-axis acceleration, and Z-axis acceleration increase, thereby improving the detection sensitivity.

[0127] Furthermore, in the sensor device 1 of the first embodiment, since sensors 101 to 106 are respectively structured using a cantilever consisting of a connector 212 and a movable part 214, and a vibrating element 270 as a crystal vibrating element with high frequency stability, the difference between the even-order components of acceleration detected by sensors 101 and 102 becomes smaller, the difference between the even-order components of acceleration detected by sensors 103 and 104 becomes smaller, and the difference between the even-order components of acceleration detected by sensors 105 and 106 becomes smaller. Therefore, according to the sensor device 1 of the first embodiment, in the vibration rectification error correction circuit 2, by calculating the difference between the acceleration values ​​in the +X direction and the -X direction, the difference between the acceleration values ​​in the +Y direction and the -Y direction, and the difference between the acceleration values ​​in the +Z direction and the -Z direction by the microcontroller unit 330, the vibration rectification error can be reduced through simple calculation.

[0128] 2. Second Implementation Method

[0129] The following description of the sensor device according to the second embodiment uses the same reference numerals as the first embodiment to refer to the same components, omits or simplifies the descriptions that are repeated in the first embodiment, and mainly describes the contents that are different from the first embodiment.

[0130] The structure of the sensor device 1 in the second embodiment is similar to... Figures 1-6 The same applies, therefore its illustrations and descriptions are omitted. Furthermore, since the functional block diagram of the sensor device 1 in the second embodiment is similar to... Figure 7The same applies, therefore its illustration and description are omitted. However, the sensor device 1 of the second embodiment differs from the sensor device 1 of the first embodiment in that the microcontroller 330 performs a process to further reduce the vibration rectification error of the acceleration value.

[0131] The frequency Y2' obtained by multiplying the frequency Y2 represented by the previously mentioned equation (6) by an arbitrary correction coefficient K can be represented by equation (10).

[0132]

Number 10

[0133] Based on equations (2) and (10) mentioned earlier, the frequency Y is obtained by subtracting frequency Y2' from frequency Y1. 1－2 It can be expressed by equation (11).

[0134]

Number 11

[0135] Here, if we assume A1 > 0 and A2 > 0, and if the condition of equation (12) is satisfied, then the frequency Y represented by equation (11) is... 1－2 The quadratic term of ' is expressed by the frequency Y in equation (8). 1－2 The quadratic term is small.

[0136]

Number 12

[0137] The range of the correction coefficient K that satisfies the condition of equation (12) is shown in equation (13).

[0138]

Number 13

[0139] Figure 9 The frequency Y1, Y2', Y is shown. 1－2 An example of the relationship between the amplitude X1 of the acceleration. Figure 9 In the diagram, the dashed lines represent the ideal straight lines when the quadratic terms of equations (2), (10), and (11) are set to 0. Figure 9 In the equation (13), A1 < A2, the correction coefficient K is set to a value within the range of A1 / A2 ≤ K < 1, and the frequency Y 1－2 'Compare Figure 8 The frequency Y shown 1－2 It is closer to the ideal straight line.

[0140] According to equation (11), the vibration rectification error VRE is the difference between the acceleration value in the +X direction and the acceleration value in the -X direction multiplied by the correction coefficient K. 1－2It can be expressed by equation (14).

[0141]

Number 14

[0142] In particular, when K = A1 / A2 is set, as shown in equation (15), the vibration rectification error VRE can be reduced. 1－2 ' is 0.

[0143]

Number 15

[0144] Therefore, in the second embodiment, the microcontroller 330 converts the count values ​​CNT_XP and CNT_XN into acceleration values ​​in the +X direction and the -X direction, respectively, and then calculates the acceleration value obtained by multiplying the -X direction acceleration value by a correction coefficient K. The correction coefficient K is determined to be a value within the range of equation (13) and is pre-stored in the storage unit 340. That is, the correction coefficient K is set based on the value of A1 / A2, where A1 / A2 is the ratio of the quadratic coefficient A1 of the approximation formula of the output signal of the sensor 101 with acceleration as the variable, i.e., equation (2), to the quadratic coefficient A2 of the approximation formula of the output signal of the sensor 102 with acceleration as the variable, i.e., equation (6). Moreover, the microcontroller 330 calculates the difference between the +X direction acceleration value and the -X direction acceleration value obtained by multiplying by the correction coefficient K as the X-axis acceleration value.

[0145] Similarly, the microcontroller 330 calculates the acceleration value obtained by multiplying the acceleration value in the -Y direction by a correction factor K, and calculates the difference between the acceleration value in the +Y direction and the acceleration value in the -Y direction obtained by multiplying by the correction factor K, as the acceleration value of the Y-axis. Likewise, the microcontroller 330 calculates the acceleration value obtained by multiplying the acceleration value in the -Z direction by a correction factor K, and calculates the difference between the acceleration value in the +Z direction and the acceleration value in the -Z direction obtained by multiplying by the correction factor K, as the acceleration value of the Z-axis. It should be noted that the correction factor K used to calculate the acceleration values ​​of the X-axis, Y-axis, and Z-axis can also be different values.

[0146] Then, the microcontroller unit 330 generates measurement data including the calculated acceleration values ​​of the X-axis, Y-axis, and Z-axis, and sends the measurement data to the external device 3 or writes it to the storage unit 340.

[0147] It should be noted that the first-order coefficient (B1 + K·B2) in equation (11) represents the frequency Y. 1－2 'The sensitivity relative to acceleration X, if K > 1, is greater than the frequency Y shown in equation (8) 1－2The sensitivity, i.e., the first-order coefficient (B1 + B2), is large. According to equation (13), when A1 > A2, since K > 1, B1 + K·B2 > B1 + B2, and the frequency Y 1－2 The sensitivity increases; however, when A1 < A2, because K < 1, therefore B1 + K·B2 < B1 + B2, and the frequency Y... 1－2 The sensitivity of ' has decreased.

[0148] Here, the frequency Y1' obtained by multiplying the frequency Y1 represented by the previously mentioned equation (2) by an arbitrary correction coefficient K can be represented by equation (16).

[0149]

Number 16

[0150] Based on equations (6) and (16) mentioned earlier, the frequency Y is obtained by subtracting frequency Y1' from frequency Y2. 2－1 It can be expressed by equation (17).

[0151]

Number 17

[0152] Here, if we assume A1 > 0 and A2 > 0, and if the condition of equation (18) is satisfied, then the frequency Y represented by equation (17) is... 2－1 The frequency Y represented by the quadratic ratio (8) of ' 1－2 The quadratic term is small.

[0153]

Number 18

[0154] The range of the correction coefficient K that satisfies the condition of equation (18) is shown in equation (19).

[0155]

Number 19

[0156] According to equation (19), when A1 > A2, since K < 1, therefore B2 + K·B1 < B1 + B2, and the frequency Y 2－1 The sensitivity of ' decreases; while in the case of A1 < A2, since K > 1, B2 + K·B1 > B1 + B2, the frequency Y 2－1 The sensitivity of 'increases'.

[0157] Figure 10 The frequency Y1', Y2, Y is shown. 2－1 An example of the relationship between the amplitude X1 of the acceleration. Figure 10In the diagram, the dashed lines represent the ideal straight lines when the quadratic terms of equations (6), (16), and (17) are set to 0. Figure 10 In the equation (19), A1 < A2, the correction coefficient K is set to a value within the range of 1 < K ≤ A1 / A2, and the frequency Y... 2－1 'Compare Figure 8 The frequency Y shown 1－2 It is closer to an ideal straight line. Furthermore, the frequency Y... 2－1 The sensitivity of ' also increases.

[0158] Therefore, it is also possible that, in order to increase the sensitivity, for the quadratic coefficients A1 and A2 of sensors 101 and 102, the microcontroller 330 calculates the difference between the acceleration value in the +X direction and the acceleration value in the -X direction obtained by multiplying by a correction coefficient K greater than 1 when A1 > A2, and uses this difference as the acceleration value of the X-axis; while when A1 < A2, it calculates the difference between the acceleration value in the +X direction and the acceleration value in the -X direction obtained by multiplying by a correction coefficient K greater than 1, and uses this difference as the acceleration value of the X-axis.

[0159] Similarly, for the quadratic coefficients A1 and A2 of sensors 103 and 104, the microcontroller 330 calculates the difference between the acceleration value in the +Y direction and the acceleration value in the -Y direction obtained by multiplying by a correction coefficient K greater than 1 when A1 > A2, and uses this difference as the acceleration value of the Y-axis; while when A1 < A2, it calculates the difference between the acceleration value in the +Y direction and the acceleration value in the -Y direction obtained by multiplying by a correction coefficient K greater than 1, and uses this difference as the acceleration value of the Y-axis. Likewise, for the quadratic coefficients A1 and A2 of sensors 105 and 106, the microcontroller 330 calculates the difference between the acceleration value in the +Z direction and the acceleration value in the -Z direction obtained by multiplying by a correction coefficient K greater than 1 when A1 > A2, and uses this difference as the acceleration value of the Z-axis; while when A1 < A2, it calculates the difference between the acceleration value in the +Z direction and the acceleration value in the -Z direction obtained by multiplying by a correction coefficient K greater than 1, and uses this difference as the acceleration value of the Z-axis.

[0160] Other configurations of the sensor device 1 in the second embodiment are the same as those in the sensor device 1 in the first embodiment, so their description is omitted.

[0161] It should be noted that in the second embodiment, sensor 101 is an example of a "first sensor," and sensor 102 is an example of a "second sensor." Furthermore, sensor 103 is another example of a "first sensor," and sensor 104 is another example of a "second sensor." Additionally, sensor 105 is another example of a "first sensor," and sensor 106 is another example of a "second sensor." The detection axis D1 of sensor 101 is an example of a "first detection axis," and the detection axis D2 of sensor 102 is an example of a "second detection axis." Furthermore, the detection axis D3 of sensor 103 is another example of a "first detection axis," and the detection axis D4 of sensor 104 is another example of a "second detection axis." Additionally, the detection axis D5 of sensor 105 is another example of a "first detection axis," and the detection axis D6 of sensor 106 is another example of a "second detection axis." The microcontroller unit 330 is an example of a "signal processing unit." The acceleration value in the +X direction calculated by the microcontroller 330 is an example of a "first signal value," and the value obtained by multiplying the acceleration value in the -X direction calculated by the microcontroller 330 by the correction factor K is an example of a "second signal value." Similarly, the acceleration value in the +Y direction calculated by the microcontroller 330 is another example of a "first signal value," and the value obtained by multiplying the acceleration value in the -Y direction calculated by the microcontroller 330 by the correction factor K is another example of a "second signal value." Furthermore, the acceleration value in the +Z direction calculated by the microcontroller 330 is another example of a "first signal value," and the value obtained by multiplying the acceleration value in the -Z direction calculated by the microcontroller 330 by the correction factor K is another example of a "second signal value."

[0162] As explained above, in the sensor device 1 of the second embodiment, in the vibration rectification error correction circuit 2, the microcontroller 330 calculates the differences between the acceleration value in the +X direction and the acceleration value in the -X direction obtained by multiplying it by the correction coefficient K, the differences between the acceleration value in the +Y direction and the acceleration value in the -Y direction obtained by multiplying it by the correction coefficient K, and the differences between the acceleration value in the +Z direction and the acceleration value in the -Z direction obtained by multiplying it by the correction coefficient K. This further reduces the even-order components of the X-axis acceleration, Y-axis acceleration, and Z-axis acceleration. Therefore, according to the sensor device 1 of the second embodiment, in the vibration rectification error correction circuit 2, the vibration rectification error can be reduced through simple calculations by the microcontroller 330.

[0163] In particular, since the quadratic component of acceleration has a significant impact on vibration rectification error, by setting the values ​​of each correction coefficient K' to be the ratio of the quadratic coefficients A1 and A2 of the coefficients of the quadratic components of the physical quantities included in the acceleration values ​​corresponding to the +X and -X directions (i.e., A1 / A2), the ratio of the quadratic coefficients A1 and A2 of the coefficients of the quadratic components of the physical quantities included in the acceleration values ​​corresponding to the +Y and -Y directions (i.e., A1 / A2), and the ratio of the quadratic coefficients A1 and A2 of the coefficients of the quadratic components of the physical quantities included in the acceleration values ​​corresponding to the +Z and -Z directions (i.e., A1 / A2), the quadratic component of triaxial acceleration is significantly reduced. Therefore, according to the sensor device 1 of the second embodiment, in the vibration rectification error correction circuit 2, the vibration rectification error can be significantly reduced through simple calculations by the microcontroller 330.

[0164] Furthermore, the sensor device 1 according to the second embodiment can achieve the same effect as the sensor device 1 according to the first embodiment.

[0165] 3. Third Implementation Method

[0166] Hereinafter, regarding the sensor device of the third embodiment, the same reference numerals are used to mark the same constituent elements as in the first embodiment, and descriptions that are repeated in the first embodiment are omitted or simplified. The description mainly focuses on the contents that are different from those in the first embodiment.

[0167] The structure of the sensor device 1 in the third embodiment and Figures 1-6 The same applies, therefore its illustrations and descriptions are omitted. Furthermore, since the functional block diagram of the sensor device 1 in the third embodiment is similar to... Figure 7 The same applies, therefore its illustrations and descriptions are omitted. However, in the sensor device 1 of the third embodiment, the microcontroller 330 performs processing to reduce the vibration rectification error of the acceleration value, which differs from the sensor device 1 of the first embodiment.

[0168] The frequency Y2” obtained by dividing the frequency Y2 represented by the previous equation (6) by any correction coefficient K' can be represented by equation (20).

[0169]

Number 20

[0170] Based on equations (2) and (20) mentioned earlier, the frequency Y is obtained by subtracting frequency Y2” from frequency Y1. 1－2 "It can be expressed by equation (21)."

[0171]

Number 21

[0172] Here, if we assume A1 > 0 and A2 > 0, and if the condition of equation (22) is satisfied, then the frequency Y represented by equation (21) 1－2 The frequency Y represented by the quadratic ratio (8) of the equation is... 1－2 The quadratic term is small.

[0173]

Number 22

[0174] The range of the correction coefficient K' that satisfies the condition of equation (22) is shown in equation (23).

[0175]

Number 23

[0176] According to equation (21), the vibration rectification error VRE is the difference between the acceleration value in the +X direction and the acceleration value in the -X direction after dividing by the correction coefficient K'. 1－2 "It can be expressed by equation (24)."

[0177]

Number 24

[0178] In particular, when K' = A2 / A1 is set, as shown in equation (25), the vibration rectification error VRE can be reduced. 1－2 "It is 0".

[0179]

Number 25

[0180] Therefore, in the third embodiment, the microcontroller 330 converts the count values ​​CNT_XP and CNT_XN into acceleration values ​​in the +X direction and -X direction, respectively, and then calculates the acceleration value obtained by dividing the acceleration value in the -X direction by the correction coefficient K'. The correction coefficient K' is determined to be a value within the range that satisfies equation (23) and is pre-stored in the storage unit 340. That is, the correction coefficient K' is set to the value of A2 / A1, which is the ratio of the quadratic coefficient A2 of equation (6) to the quadratic coefficient A1 of equation (2), where equation (6) is an approximation of the output signal of the sensor 102 with acceleration as a variable, and equation (2) is an approximation of the output signal of the sensor 101 with acceleration as a variable. Moreover, the microcontroller 330 calculates the difference between the acceleration value in the +X direction and the acceleration value in the -X direction obtained by dividing by the correction coefficient K', and uses it as the acceleration value of the X-axis.

[0181] Similarly, the microcontroller 330 calculates the acceleration value obtained by dividing the acceleration value in the -Y direction by the correction coefficient K', and calculates the difference between the acceleration value in the +Y direction and the acceleration value in the -Y direction obtained by dividing by the correction coefficient K', as the acceleration value of the Y-axis. Likewise, the microcontroller 330 calculates the acceleration value obtained by dividing the acceleration value in the -Z direction by the correction coefficient K', and calculates the difference between the acceleration value in the +Z direction and the acceleration value in the -Z direction obtained by dividing by the correction coefficient K', as the acceleration value of the Z-axis. It should be noted that the correction coefficient K' used to calculate the acceleration values ​​of the X-axis, Y-axis, and Z-axis can also be different values.

[0182] Then, the microcontroller unit 330 generates measurement data including the calculated acceleration values ​​of the X-axis, Y-axis, and Z-axis, and sends the measurement data to the external device 3 or writes it to the storage unit 340.

[0183] It should be noted that the first-order coefficient (B1 + B2 / K') in equation (21) represents the frequency Y. 1－2 "The sensitivity to acceleration X, and if K' < 1, then the frequency Y shown in equation (8) is greater." 1－2 The sensitivity, i.e., the first-order coefficient (B1+B2), is large. According to equation (23), when A1>A2, since K'<1, B1+B2 / K'>B1+B2, the frequency Y 1－2 The sensitivity increases; however, in the case of A1 < A2, because K' > 1, B1 + B2 / K' < B1 + B2, and the frequency Y... 1－2 The sensitivity of "" decreases.

[0184] Here, the frequency Y1” obtained by dividing the frequency Y1 represented by the previous equation (2) by any correction coefficient K' can be represented by equation (26).

[0185]

Number 26

[0186] Based on equations (6) and (26) mentioned above, the frequency Y is obtained by subtracting frequency Y1” from frequency Y2. 2－1 "It can be expressed by equation (27)."

[0187]

Number 27

[0188] Here, when we assume A1 > 0 and A2 > 0, if the condition of equation (28) is satisfied, then the frequency Y represented by equation (27) is... 2－1 The frequency Y represented by the quadratic ratio (8) of the equation is... 1－2The quadratic term is small.

[0189]

Number 28

[0190] The range of the correction coefficient K' that satisfies the condition of equation (28) is shown in equation (29).

[0191]

Number 29

[0192] According to equation (29), when A1 > A2, since K' > 1, therefore B2 + B1 / K' < B1 + B2, and the frequency Y 2－1 The sensitivity of "Y" decreases; while in the case of A1 < A2, since K' < 1, B2 + B1 / K' > B1 + B2, the frequency Y 2－1 The sensitivity of "" increases.

[0193] Therefore, it is also possible that, in order to increase the sensitivity, for the quadratic coefficients A1 and A2 of sensors 101 and 102, the microcontroller 330 calculates the difference between the acceleration value in the +X direction and the acceleration value in the -X direction obtained by dividing by a correction coefficient K' less than 1 when A1 > A2, and uses this difference as the acceleration value of the X-axis; while when A1 < A2, it calculates the difference between the acceleration value in the +X direction obtained by dividing by a correction coefficient K' less than 1 and the acceleration value in the -X direction, and uses this difference as the acceleration value of the X-axis.

[0194] Similarly, for the quadratic coefficients A1 and A2 of sensors 103 and 104, if A1 > A2, the microcontroller 330 calculates the difference between the acceleration value in the +Y direction and the acceleration value in the -Y direction obtained by dividing by a correction coefficient K' less than 1, and uses this difference as the acceleration value of the Y-axis; while if A1 < A2, it calculates the difference between the acceleration value in the +Y direction obtained by dividing by a correction coefficient K' less than 1 and the acceleration value in the -Y direction, and uses this difference as the acceleration value of the Y-axis. Similarly, for the quadratic coefficients A1 and A2 of sensors 105 and 106, if A1 > A2, the microcontroller 330 calculates the difference between the acceleration value in the +Z direction and the acceleration value in the -Z direction obtained by dividing by a correction coefficient K' less than 1, and uses this difference as the acceleration value of the Z-axis; while if A1 < A2, it calculates the difference between the acceleration value in the +Z direction obtained by dividing by a correction coefficient K' less than 1 and the acceleration value in the -Z direction, and uses this difference as the acceleration value of the Z-axis.

[0195] Other configurations of the sensor device 1 in the third embodiment are the same as those in the sensor device 1 in the first embodiment, so their description is omitted.

[0196] It should be noted that in the third embodiment, sensor 101 is an example of a "first sensor," and sensor 102 is an example of a "second sensor." Furthermore, sensor 103 is another example of a "first sensor," and sensor 104 is another example of a "second sensor." Additionally, sensor 105 is another example of a "first sensor," and sensor 106 is another example of a "second sensor." The detection axis D1 of sensor 101 is an example of a "first detection axis," and the detection axis D2 of sensor 102 is an example of a "second detection axis." Furthermore, the detection axis D3 of sensor 103 is another example of a "first detection axis," and the detection axis D4 of sensor 104 is another example of a "second detection axis." Additionally, the detection axis D5 of sensor 105 is another example of a "first detection axis," and the detection axis D6 of sensor 106 is another example of a "second detection axis." The microcontroller unit 330 is an example of a "signal processing unit." The acceleration value in the +X direction calculated by the microcontroller 330 is one example of a "first signal value," and the value obtained by dividing the acceleration value in the -X direction calculated by the microcontroller 330 by the correction coefficient K' is another example of a "second signal value." Similarly, the acceleration value in the +Y direction calculated by the microcontroller 330 is another example of a "first signal value," and the value obtained by dividing the acceleration value in the -Y direction calculated by the microcontroller 330 by the correction coefficient K' is another example of a "second signal value."

[0197] As explained above, in the sensor device 1 of the third embodiment, in the vibration rectification error correction circuit 2, the microcontroller 330 calculates the differences between the acceleration value in the +X direction and the acceleration value in the -X direction (obtained by dividing by the correction coefficient K'), the acceleration value in the +Y direction and the acceleration value in the -Y direction (obtained by dividing by the correction coefficient K'), and the acceleration value in the +Z direction and the acceleration value in the -Z direction (obtained by dividing by the correction coefficient K'), further reducing the even-order components of the X-axis acceleration, Y-axis acceleration, and Z-axis acceleration. Therefore, according to the sensor device 1 of the third embodiment, in the vibration rectification error correction circuit 2, the vibration rectification error can be reduced through simple calculations by the microcontroller 330.

[0198] In particular, since the quadratic component of acceleration has a significant impact on vibration rectification error, by setting the values ​​of their respective correction coefficients K' to the ratio of the quadratic coefficients A2 and A1 of the coefficients of the quadratic components of the physical quantities included in the acceleration values ​​in the -X and +X directions (i.e., A2 / A1), the ratio of the quadratic coefficients A2 and A1 of the coefficients of the quadratic components of the physical quantities included in the acceleration values ​​in the -Y and +Y directions (i.e., A2 / A1), and the ratio of the quadratic coefficients A2 and A1 of the coefficients of the quadratic components of the physical quantities included in the acceleration values ​​in the -Z and +Z directions (i.e., A2 / A1), the quadratic component of triaxial acceleration is significantly reduced. Therefore, according to the sensor device 1 of the third embodiment, in the vibration rectification error correction circuit 2, the vibration rectification error can be significantly reduced through simple calculations by the microcontroller 330.

[0199] Furthermore, the sensor device 1 according to the third embodiment can achieve the same effect as the sensor device 1 according to the first embodiment.

[0200] 4. Variations

[0201] This invention is not limited to this embodiment, and various modifications can be implemented within the scope of the spirit of this invention.

[0202] For example, in the above embodiments, the sensor device 1 has six sensors 101 to 106, but the number of sensors in the sensor device 1 can be less than five or more than seven.

[0203] Furthermore, while the above embodiments exemplify a sensor device 1 equipped with an acceleration sensor, sensor device 1 may also include sensors such as angular velocity sensors, pressure sensors, and optical sensors. Additionally, sensor device 1 may include two or more sensors selected from various types of sensors, such as acceleration sensors, angular velocity sensors, pressure sensors, and optical sensors.

[0204] Furthermore, in the above embodiments, a crystal-based element is used as the sensor element 200 of each of the sensors 101 to 106. However, the sensor element 200 can be made of a piezoelectric element other than crystal, or it can be a capacitive MEMS element. MEMS is an abbreviation for Micro Electro Mechanical Systems.

[0205] The above-described embodiments and modifications are merely examples and are not intended to limit the scope. For instance, various embodiments and modifications can be appropriately combined.

[0206] This invention includes configurations that are substantially the same as those described in the embodiments, such as having the same function, method, and result, or the same purpose and effect. Additionally, this invention includes configurations obtained by replacing non-essential parts in the configurations described in the embodiments. Furthermore, this invention includes configurations that can achieve the same function or effect as those described in the embodiments, or achieve the same purpose. Additionally, this invention includes configurations that incorporate known technologies into the configurations described in the embodiments.

[0207] The following content can be derived from the above implementation methods and variations.

[0208] One method of vibration rectification error correction circuit includes: The signal processing unit calculates the difference between a first signal value and a second signal value, wherein the first signal value is a signal value of a physical quantity detected by a first sensor having a first detection axis, and the second signal value is a signal value of the physical quantity detected by a second sensor having a second detection axis opposite in direction to the first detection axis. The vibration rectification error of the difference is smaller than the vibration rectification error of the first signal value and smaller than the vibration rectification error of the second signal value.

[0209] In this vibration rectification error correction circuit, vibration rectification error occurs in both the first and second signal values ​​because they each contain even-order components of the physical quantity. However, by calculating the difference between the first and second signal values, the even-order components of the physical quantity are reduced. Therefore, this vibration rectification error correction circuit can reduce the vibration rectification error through simple calculations.

[0210] Furthermore, in this vibration rectification error correction circuit, since the detection axes of the first and second sensors are opposite, the primary components of the physical quantity included in the first and second signal values ​​have opposite signs. Therefore, according to this vibration rectification error correction circuit, because the value of the primary component of the physical quantity increases by calculating the difference between the first and second signal values, the detection sensitivity is improved.

[0211] In one embodiment of the vibration rectification error correction circuit, it can also be that... The second signal value is obtained by multiplying the signal value of the physical quantity detected by the second sensor by a correction coefficient.

[0212] In this vibration rectification error correction circuit, the even-order components of the physical quantity are further reduced by calculating the difference between the first signal value and the second signal value obtained by multiplying it by the correction coefficient. Therefore, according to this vibration rectification error correction circuit, the vibration rectification error can be further reduced through simple calculations.

[0213] In one embodiment of the vibration rectification error correction circuit, it can also be that... The value of the correction coefficient is the ratio of the quadratic coefficient of the approximation of the output signal of the first sensor with the physical quantity as the variable to the quadratic coefficient of the approximation of the output signal of the second sensor with the physical quantity as the variable.

[0214] In this vibration rectification error correction circuit, since the quadratic component of the physical quantity has a significant impact on the vibration rectification error, the quadratic component of the physical quantity is greatly reduced by setting the correction coefficient to a value that is based on the ratio of the quadratic coefficients of the coefficients of the quadratic components of the physical quantity included in the first signal value and the second signal value, respectively. Therefore, according to this vibration rectification error correction circuit, the vibration rectification error can be significantly reduced through simple calculations.

[0215] In one embodiment of the vibration rectification error correction circuit, it can also be that... The second signal value is obtained by dividing the signal value of the physical quantity detected by the second sensor by a correction coefficient.

[0216] In this vibration rectification error correction circuit, the even-order components of the physical quantity are further reduced by calculating the difference between the first signal value and the second signal value obtained by dividing by the correction coefficient. Therefore, according to this vibration rectification error correction circuit, the vibration rectification error can be further reduced through simple calculations.

[0217] In one embodiment of the vibration rectification error correction circuit, it can also be that... The value of the correction coefficient is the ratio of the quadratic coefficient of the approximation of the output signal of the second sensor with the physical quantity as the variable to the quadratic coefficient of the approximation of the output signal of the first sensor with the physical quantity as the variable.

[0218] In this vibration rectification error correction circuit, since the quadratic component of the physical quantity has a significant impact on the vibration rectification error, the quadratic component of the physical quantity is greatly reduced by setting the correction coefficient to the ratio of the quadratic coefficients of the coefficients of the quadratic components of the physical quantity included in the second signal value and the first signal value, respectively. Therefore, according to this vibration rectification error correction circuit, the vibration rectification error can be significantly reduced through simple calculations.

[0219] In one embodiment of the vibration rectification error correction circuit, it can also be that... The physical quantity mentioned is acceleration. The first sensor and the second sensor each include: A cantilever, by applying the physical quantity to the cantilever, causing the cantilever to deform; and A crystal vibrating element whose vibration frequency changes due to stress generated by deformation of the cantilever.

[0220] According to this vibration rectification error correction circuit, the first and second sensors detect acceleration using cantilever and high-frequency-stability crystal resonant elements, respectively. This reduces the difference between the even-order components of the acceleration detected by the first and second sensors. Therefore, by calculating the difference between the first and second signal values ​​using this vibration rectification error correction circuit, the vibration rectification error can be reduced through simple calculations.

[0221] One method of sensor device includes: One method of the vibration rectification error correction circuit; The first sensor; and The second sensor.

[0222] According to this sensor device, by having a vibration rectification error correction circuit and a first sensor and a second sensor with opposite detection axis directions, measurement data with reduced vibration rectification error can be generated through simple calculation.

Claims

1. A vibration rectification error correction circuit, characterized in that, include: The signal processing unit calculates the difference between a first signal value and a second signal value, wherein the first signal value is a signal value of a physical quantity detected by a first sensor having a first detection axis, and the second signal value is a signal value of the physical quantity detected by a second sensor having a second detection axis in the opposite direction to the first detection axis. The vibration rectification error of the difference is smaller than the vibration rectification error of the first signal value and smaller than the vibration rectification error of the second signal value.

2. The vibration rectification error correction circuit according to claim 1, characterized in that, The second signal value is obtained by multiplying the signal value of the physical quantity detected by the second sensor by a correction coefficient.

3. The vibration rectification error correction circuit according to claim 2, characterized in that, The value of the correction coefficient is the ratio of the quadratic coefficient of the approximation of the output signal of the first sensor with the physical quantity as the variable to the quadratic coefficient of the approximation of the output signal of the second sensor with the physical quantity as the variable.

4. The vibration rectification error correction circuit according to claim 1, characterized in that, The second signal value is obtained by dividing the signal value of the physical quantity detected by the second sensor by a correction factor.

5. The vibration rectification error correction circuit according to claim 4, characterized in that, The value of the correction coefficient is the ratio of the quadratic coefficient of the approximation of the output signal of the second sensor with the physical quantity as the variable to the quadratic coefficient of the approximation of the output signal of the first sensor with the physical quantity as the variable.

6. The vibration rectification error correction circuit according to claim 1, characterized in that, The physical quantity mentioned is acceleration. The first sensor and the second sensor each include: A cantilever, by applying the physical quantity to the cantilever, causing the cantilever to deform; and A crystal vibrating element whose vibration frequency changes due to stress generated by deformation of the cantilever.

7. A sensor device, characterized in that, have: Vibration rectification error correction circuit as described in any one of claims 1 to 6; The first sensor; and The second sensor.

Images