Inertial Sensor Module

Abstract

To provide an inertial sensor module having high detection accuracy relative to a specific one axis.SOLUTION: An inertial sensor module includes: a first inertial sensor having a first axis as a detection axis; a second inertial sensor having the first axis as a detection axis; and an operational circuit. The first inertial sensor has higher detection accuracy than the second inertial sensor. A detection signal of the first axis, which is output from the first inertial sensor, and a detection signal of the first axis, which is output from the second inertial sensor, are input into the operational circuit, so that the operational circuit selects and outputs one of a first output signal based on the detection signal of the first axis, which is output from the first inertial sensor, and a second output signal based on the detection signal of the first axis, which is output from the second inertial sensor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inertial sensor module. [Background technology]

[0002] Patent Document 1 describes an inertial sensor module that includes a three-axis acceleration sensor and a three-axis gyro sensor formed from a silicon substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-31358 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been an increasing demand for higher accuracy in inertial sensor modules. For example, in systems that control vehicle attitude, inertial sensor modules are installed on vehicles to calculate the vehicle's roll angle, pitch angle, and yaw angle, and yaw angle in particular must be calculated accurately. Therefore, there is a demand for inertial sensor modules that can detect angular velocity along three axes and also detect angular velocity along one axis with high accuracy. However, inertial sensor modules equipped with three-axis silicon MEMS sensors may not be able to meet the demand for high detection accuracy along a specific axis. [Means for solving the problem]

[0005] One aspect of the inertial sensor module according to the present invention is a first inertial sensor having a first axis as a detection axis; a second inertial sensor having the first axis as a detection axis; an arithmetic circuit; Equipped with the detection accuracy of the first inertial sensor is higher than the detection accuracy of the second inertial sensor; The arithmetic circuit receives the detection signal of the first axis output from the first inertial sensor and the detection signal of the first axis output from the second inertial sensor, and selects and outputs either a first output signal based on the detection signal of the first axis output from the first inertial sensor or a second output signal based on the detection signal of the first axis output from the second inertial sensor.

[0006] Another aspect of the inertial sensor module according to the present invention is a first inertial sensor having a first axis as a detection axis; a second inertial sensor having the first axis as a detection axis; an arithmetic circuit; Equipped with the detection accuracy of the first inertial sensor is higher than the detection accuracy of the second inertial sensor; The arithmetic circuit receives the detection signal of the first axis output from the first inertial sensor and the detection signal of the first axis output from the second inertial sensor, and corrects the detection signal of the first axis output from the first inertial sensor when the magnitude of the detection signal of the first axis output from the second inertial sensor is within a predetermined range. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram showing an example of the functional configuration of the inertial sensor module according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of an arithmetic circuit. [Figure 3] FIG. 2 is a plan view of the inertial sensor module. [Figure 4] Cross-sectional view of the inertial sensor module taken along line AA in Figure 3. [Figure 5] FIG. 2 is a plan view of the first inertial sensor. [Figure 6] FIG. [Figure 7] 3 is a diagram showing an example of input / output characteristics of the sensor element 11 and the first sensor element 21. FIG. [Figure 8] FIG. 10 is a diagram showing an example of the configuration of an arithmetic circuit according to the second embodiment. [Figure 9] FIG. 3 is a diagram showing an example of temperature characteristics of the sensor element 11 and the first sensor element 21. [Figure 10] FIG. 10 is a diagram showing an example of the functional configuration of an inertial sensor module according to a third embodiment. [Figure 11] FIG. 11 is a plan view of a second inertial sensor according to a third embodiment. [Figure 12] FIG. 10 is a diagram showing an example of the configuration of an arithmetic circuit according to the fourth embodiment. [Figure 13] FIG. 13 is a diagram showing an example of the configuration of an arithmetic circuit according to the fifth embodiment. [Figure 14] FIG. 10 is a diagram showing an example of a functional configuration of an inertial sensor module according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that the embodiments described below do not unduly limit the content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0009] 1. First embodiment Fig. 1 is a diagram showing an example of the functional configuration of the inertial sensor module 1 of the first embodiment. As shown in Fig. 1, the inertial sensor module 1 of the first embodiment includes a first inertial sensor 10, a second inertial sensor 20, an arithmetic circuit 30, and a temperature sensor 40. Note that the inertial sensor module 1 may be configured such that some of the components shown in Fig. 1 are omitted or modified, or other components are added.

[0010] The first inertial sensor 10 is a sensor with a first axis as its detection axis, and includes a sensor element 11 and a processing circuit 12. The first inertial sensor 10 is a device in which a printed circuit board on which the sensor element 11 and the processing circuit 12 are mounted is housed in a package. The processing circuit 12 is, for example, an IC chip realized by a semiconductor. IC stands for Integrated Circuit. The first inertial sensor 10 also has terminals for external connection provided on the package, such as terminals TCS1, terminal TCK1, terminal TDI1, terminal TDO1, and terminal TS1.

[0011] The second inertial sensor 20 is a sensor having a first axis as a detection axis, and further having a second axis and a third axis as detection axes, and includes a first sensor element 21, a second sensor element 22, a third sensor element 23, and a processing circuit 27. The second inertial sensor 20 is a device in which a silicon substrate on which the first sensor element 21, the second sensor element 22, the third sensor element 23, and the processing circuit 27 are formed is housed in a package. The processing circuit 27 is an IC formed on the silicon substrate. The second inertial sensor 20 also has terminals for external connection provided on the package, such as terminals TCS2, TCK2, TDI2, TDO2, and TS2.

[0012] The sensor element 11 and the first sensor element 21 are both sensor elements that detect the same type of physical quantity using the first axis as the detection axis. The physical quantity is, for example, angular velocity, acceleration, angular acceleration, velocity, distance, pressure, sound pressure, or magnetic quantity. For example, when the three orthogonal axes are the X-axis, Y-axis, and Z-axis, the sensor element 11 and the first sensor element 21 may both detect angular velocity around the Z-axis, or may both detect acceleration in the X-axis direction.

[0013] The second sensor element 22 is a sensor element that detects a physical quantity using a second axis, which is different from the first axis, as a detection axis. The third sensor element 23 is a sensor element that detects a physical quantity using a third axis, which is different from the first and second axes, as a detection axis. The physical quantities detected by the first sensor element 21, the second sensor element 22, and the third sensor element 23 may be the same or different. For example, the first sensor element 21 may detect an angular velocity about the Z axis, the second sensor element 22 may detect an angular velocity about the X axis, and the third sensor element 23 may detect an angular velocity about the Y axis. Alternatively, the first sensor element 21 may detect an angular velocity about the Z axis, the second sensor element 22 may detect acceleration in the X axis direction, and the third sensor element 23 may detect acceleration in the Y axis direction.

[0014] The processing circuit 12 performs a physical quantity detection process on the signal output from the sensor element 11 and outputs first detection data SD1 obtained by the detection process. The processing circuit 12 includes a detection circuit 121 that performs a physical quantity detection process on the signal output from the sensor element 11 and an interface circuit 122 that outputs the first detection data SD1 obtained by the detection process of the detection circuit 121. For example, the detection circuit 121 may include an amplifier circuit that amplifies the signal output from the sensor element 11, a detector circuit that detects the output signal of the amplifier circuit, a gain adjustment circuit that adjusts the voltage of the output signal of the detector circuit, an offset adjustment circuit that adjusts the offset of the output signal of the gain adjustment circuit, and an A / D conversion circuit that converts the output signal of the offset adjustment circuit into a digital signal. The interface circuit 122 receives the digital signal output from the A / D conversion circuit of the detection circuit 121 as first detection data SD1 in accordance with the timing of the external synchronization signal EXSYC input from the terminal TCS1 and outputs the first detection data SD1 in response to a read command from the calculation circuit 30. The first detection data SD1 includes a detection signal of the first axis detected by the sensor element 11.

[0015] The processing circuit 27 performs a physical quantity detection process on the signals output from the first sensor element 21, the second sensor element 22, and the third sensor element 23, respectively, and outputs second detection data SD2 obtained by the detection process. The processing circuit 27 includes a detection circuit 271 that performs a physical quantity detection process on the signals output from the first sensor element 21, the second sensor element 22, and the third sensor element 23, respectively, and an interface circuit 272 that outputs the second detection data SD2 obtained by the detection process of the detection circuit 271. For example, the detection circuit 271 may include three amplifier circuits that amplify the signals output from the first sensor element 21, the second sensor element 22, and the third sensor element 23, respectively, three detector circuits that detect the output signals of each amplifier circuit, three gain adjustment circuits that adjust the voltage of the output signals of each detector circuit, three offset adjustment circuits that adjust the offset of the output signal of each gain adjustment circuit, and an A / D conversion circuit that converts the output signals of each offset adjustment circuit into digital signals in a time-division manner. The interface circuit 272 receives the digital signal output from the A / D conversion circuit of the detection circuit 271 as second detection data SD2 at the timing of the external synchronization signal EXSYC input from the terminal TCS2, and outputs the second detection data SD2 in response to a read command from the arithmetic circuit 30. The second detection data SD2 includes a detection signal of the first axis by the first sensor element 21, a detection signal of the second axis by the second sensor element 22, and a detection signal of the third axis by the third sensor element 23.

[0016] The external synchronization signal EXSYC is a signal supplied from a host device or the like, and is a signal that becomes active at each synchronization timing. For example, the external synchronization signal EXSYC is a signal that becomes active at regular intervals. Active means high level in the case of positive logic and low level in the case of negative logic. The first inertial sensor 10 and the second inertial sensor 20 can generate first detection data SD1 and second detection data SD2 at appropriate timings synchronized with each other using the external synchronization signal EXSYC, and output them to the arithmetic circuit 30.

[0017] The inertial sensor module 1 includes a digital interface bus BS that electrically connects the first inertial sensor 10, the second inertial sensor 20, and the arithmetic circuit 30.

[0018] The digital interface bus BS is a bus that complies with the communication standard for the interface processing performed by the interface circuit 122 and the interface circuit 272. In this embodiment, the digital interface bus BS is a bus that complies with the SPI communication standard and includes two data signal lines, a clock signal line, and a chip select signal line. SPI stands for Serial Peripheral Interface. Specifically, the first inertial sensor 10 is electrically connected to the digital interface bus BS via terminals TCS1, TCK1, TDI1, and TDO1. The second inertial sensor 20 is electrically connected to the digital interface bus BS via terminals TCS2, TCK2, TDI2, and TDO2. The arithmetic circuit 30 is electrically connected to the digital interface bus BS via terminals TMCS, TMCK, TMDO, and TMDI. Here, "electrically connected" refers to a connection that allows electrical signals to be transmitted, i.e., a connection that allows information to be transmitted via electrical signals. However, the digital interface bus BS may be a bus that complies with the I2C communication standard, a communication standard that is an extension of SPI or I2C, or a communication standard that is an improvement or modification of the SPI or I2C standard. I2C is an abbreviation for Inter-Integrated Circuit.

[0019] The arithmetic circuit 30 is a master controller for the first inertial sensor 10 and the second inertial sensor 20. The arithmetic circuit 30 is an integrated circuit device, and is realized by a processor such as an MPU or CPU. Alternatively, the arithmetic circuit 30 may be realized by an ASIC using automatic placement and routing such as a gate array.

[0020] The arithmetic circuit 30 outputs a chip select signal XMCS from the terminal TMCS, a serial clock signal MSCLK from the terminal TMCK, and a serial data signal MSDI from the terminal TMDO. The interface circuit 122 performs interface processing according to the SPI communication standard based on the chip select signal XMCS input from the terminal TCS1, the serial clock signal MSCLK input from the terminal TCK1, and the serial data signal MSDI input from the terminal TDI1. If the serial data signal MSDI is a read command for the first detected data SD1, the interface circuit 272 performs interface processing according to the SPI communication standard based on the chip select signal XMCS input from the terminal TCS2, the serial clock signal MSCLK input from the terminal TCK2, and the serial data signal MSDI input from the terminal TDI2. If the serial data signal MSDI is a read command for the second detected data SD2, the interface circuit 272 outputs the second detected data SD2 from the terminal TDO2. The first detection data SD1 output from the terminal TDO1 of the first inertial sensor 10 and the second detection data SD2 output from the terminal TDO2 of the second inertial sensor 20 are input to the terminal TMDI of the arithmetic circuit 30 as serial data signals MSDO, respectively.

[0021] When an external synchronization signal EXSYC is input from the terminal TSYC, the arithmetic circuit 30 reads the first detection data SD1 and the second detection data SD2 and performs various arithmetic operations on the first detection data SD1 and the second detection data SD2. Specifically, the arithmetic circuit 30 performs downsampling, filtering, correction, and the like on the first detection data SD1 and the second detection data SD2. For example, as one of the correction operations, the arithmetic circuit 30 performs a temperature correction operation on the first detection data SD1 and the second detection data SD2 based on the temperature signal TMPO input from the terminal TSEN. The temperature signal TMPO is output from the temperature sensor 40. For example, the temperature signal TMPO may be a digital signal whose frequency changes according to temperature, or a digital signal obtained by A / D conversion of an analog signal whose voltage changes according to temperature. Alternatively, the temperature sensor 40 may output a temperature signal TMPO whose voltage changes according to temperature, and the arithmetic circuit 30 may convert the temperature signal TMPO into a digital signal using an internal A / D conversion circuit to perform the temperature correction operation. Furthermore, the arithmetic circuit 30 may perform calculations based on the first detection data SD1 and the second detection data SD2 to calculate the attitude and position of the inertial sensor module 1. The temperature sensor 40 may be provided in the first inertial sensor 10 or the second inertial sensor 20.

[0022] In addition, in this embodiment, the arithmetic circuit 30 receives the first axis detection signal output from the first inertial sensor 10 and the first axis detection signal output from the second inertial sensor 20, and selects and outputs either a first output signal for the first axis based on the first axis detection signal output from the first inertial sensor 10 or a second output signal for the first axis based on the first axis detection signal output from the second inertial sensor 20.

[0023] Specifically, the arithmetic circuit 30 receives first detection data SD1 including a detection signal for the first axis output from the first inertial sensor 10 and second detection data SD2 including a detection signal for the first axis, a detection signal for the second axis, and a detection signal for the third axis output from the second inertial sensor 20. The arithmetic circuit 30 performs arithmetic processing on the first detection data SD1 to generate a first output signal for the first axis based on the detection signal for the first axis output from the first inertial sensor 10. The arithmetic circuit 30 also performs arithmetic processing on the second detection data SD2 to generate a second output signal for the first axis based on the detection signal for the first axis output from the second inertial sensor 20, a second output signal for the second axis based on the detection signal for the second axis output from the second inertial sensor 20, and a third output signal based on the detection signal for the third axis output from the second inertial sensor 20. The arithmetic circuit 30 selects either the first output signal for the first axis or the second output signal for the first axis.

[0024] In this embodiment, the arithmetic circuit 30 selects and outputs either the first output signal for the first axis or the second output signal for the first axis depending on the range of motion acting on the first axis of the first inertial sensor 10 and the second inertial sensor 20. The motion acting on the first axis is motion that generates a physical quantity for the first axis, and may be, for example, rotational motion or translational motion. The arithmetic circuit 30 may select the first output signal for the first axis when the magnitude of the motion acting on the first axis is within a predetermined range, or may select the second output signal for the first axis when the magnitude of the motion acting on the first axis is not within the predetermined range. The motion acting on the first axis generates, for example, angular velocity around the first axis, acceleration in the first axis direction, vibration, shock, etc. When the first inertial sensor 10 is a sensor that detects angular velocity or acceleration about the first axis, and the second inertial sensor 20 is a sensor that detects angular velocity or acceleration about the first, second, and third axes, the magnitude of the first output signal for the first axis and the magnitude of the second output signal for the first axis are correlated with the magnitude of the motion acting on the first axis. Therefore, the calculation circuit 30 can select either the first output signal of the first axis or the second output signal of the first axis based on at least one of the magnitude of the first output signal of the first axis and the magnitude of the second output signal of the first axis.

[0025] When the arithmetic circuit 30 selects the first output signal of the first axis, the arithmetic circuit 30 synchronizes the first output signal of the first axis, the output signal of the second axis, and the output signal of the third axis with each other and outputs them to the outside. When the arithmetic circuit 30 selects the second output signal of the first axis, the output signal of the second axis, and the output signal of the third axis with each other and output them to the outside. Specifically, the arithmetic circuit 30 generates three-axis output data including the first output signal of the first axis, the output signal of the second axis, and the output signal of the third axis that are synchronized with each other, or three-axis output data including the second output signal of the first axis, the output signal of the second axis, and the output signal of the third axis that are synchronized with each other, and outputs it to a host device (not shown).

[0026] In this embodiment, the arithmetic circuit 30 is electrically connected to the host device via terminals TR, THCS, THCK, THDI, and THDO. The host device is a master controller for the arithmetic circuit 30. When the arithmetic circuit 30 completes the generation of three-axis output data, it outputs a signal DRDY from terminal TR to the host device, indicating that the three-axis output data is ready. When the host device receives the signal DRDY, it outputs a chip select signal XHCS, a serial clock signal HSCLK, and a serial data signal HSDI, which is a read command for the three-axis output data, to the arithmetic circuit 30, in compliance with the SPI communication standard. The arithmetic circuit 30 performs interface processing according to the SPI communication standard based on the chip select signal XHCS input from terminal THCS, the serial clock signal HSCLK input from terminal THCK, and the serial data signal HSDI input from terminal THDI, and outputs the three-axis output data to terminal THDO. The three-axis output data output from terminal THDO of the arithmetic circuit 30 is input to the host device as a serial data signal HSDO.

[0027] 2 is a diagram showing an example of the configuration of the arithmetic circuit 30. As shown in FIG. 2, the arithmetic circuit 30 includes a digital interface circuit 31, a processing circuit 32, a signal processing circuit 33, an interrupt controller 34, and a host interface circuit 35.

[0028] The digital interface circuit 31 is a circuit that performs interface processing with the first inertial sensor 10 and the second inertial sensor 20. That is, the digital interface circuit 31 performs interface processing as a master between the interface circuit 122 and the interface circuit 272. The digital interface circuit 31 is connected to the digital interface bus BS via terminals TMCS, TMCK, TMDO, and TMDI. In this embodiment, the digital interface circuit 31 performs interface processing according to the SPI communication standard, similar to the interface circuit 122 and the interface circuit 272. However, the digital interface circuit 31 may also perform interface processing according to the I2C communication standard, a communication standard that is an extension of the SPI or I2C standard, or a communication standard that is an improved or modified version of the SPI or I2C standard. The digital interface bus BS and the digital interface circuit 31 may be provided in common to the first inertial sensor 10 and the second inertial sensor 20, or may be provided separately for the first inertial sensor 10 and the second inertial sensor 20.

[0029] The host interface circuit 35 is a circuit that performs interface processing with the host device. That is, the host interface circuit 35 performs interface processing as a slave with the host device. The host interface circuit 35 performs interface processing with the host device according to the SPI communication standard via the terminals THCS, THCK, THDO, and THDI. However, the host interface circuit 35 may also perform interface processing according to the I2C communication standard, a communication standard that is an extension of SPI or I2C, or a communication standard that is an improvement or modification of the SPI or I2C standard.

[0030] The processing circuit 32 is a circuit corresponding to the core CPU of the arithmetic circuit 30, and executes various types of arithmetic processing and control processing. The processing circuit 32 includes a register unit 321 having various types of registers.

[0031] The signal processing circuit 33 is a circuit that performs digital signal processing such as various calculations, and is realized by a DSP or the like. DSP stands for Digital Signal Processor. In this embodiment, the signal processing circuit 33 includes a filter circuit 331 and a correction circuit 332. The filter circuit 331 performs filter calculations on the first detection data SD1 and the second detection data SD2 to reduce unnecessary signal components. The correction circuit 332 performs various correction calculations. For example, the correction circuit 332 performs temperature correction calculations on the first detection data SD1 and the second detection data SD2 based on the temperature signal TMPO input from the terminal TSEN and a temperature correction table stored in a memory (not shown). The correction circuit 332 may perform correction calculations such as zero-point correction, sensitivity correction, and nonlinearity correction on the first detection data SD1 and the second detection data SD2. The signal processing circuit 33 may also calculate a moving average of the most recent J pieces of first detection data SD1 and second detection data SD2, and then perform down-sampling at a rate of 1 / K. J and K are each an integer of 2 or greater.

[0032] The signal processing circuit 33 may also include an attitude calculation circuit 333 and a position calculation circuit 334. The attitude calculation circuit 333 calculates the attitude of the inertial sensor module 1 based on the detection signal of the first axis included in the first detection data SD1 or the second detection data SD2, the detection signal of the second axis included in the second detection data SD2, and the detection signal of the third axis included in the second detection data SD2. The position calculation circuit 334 calculates the position of the inertial sensor module 1 based on the detection signal of the first axis included in the first detection data SD1 or the second detection data SD2, the detection signal of the second axis included in the second detection data SD2, and the detection signal of the third axis included in the second detection data SD2.

[0033] The processing circuit 32 sets the detection signal of the first axis included in the first detection data SD1 after arithmetic processing by the signal processing circuit 33 as the first output signal of the first axis. In addition, the processing circuit 32 sets the detection signal of the first axis included in the second detection data SD2 after arithmetic processing by the signal processing circuit 33 as the first output signal of the first axis, the detection signal of the second axis as the output signal of the second axis, and the detection signal of the third axis as the output signal of the third axis.

[0034] The processing circuit 32 includes an output selection circuit 322. The output selection circuit 322 selects either the first output signal of the first axis or the second output signal of the first axis based on at least one of the first output signal of the first axis and the second output signal of the first axis in accordance with the range of motion acting on the first axis. When the output selection circuit 322 selects the first output signal of the first axis, it generates three-axis output data including the first output signal of the first axis, the output signal of the second axis, and the output signal of the third axis that are synchronized with each other, and stores the data in the data register of the register unit 321. When the output selection circuit 322 selects the second output signal of the first axis, it generates three-axis output data including the second output signal of the first axis, the output signal of the second axis, and the output signal of the third axis that are synchronized with each other, and stores the data in the data register of the register unit 321.

[0035] The processing circuit 32 also generates a signal DRDY indicating that the three-axis output data is ready, and outputs the signal DRDY to the host device via the terminal TR.

[0036] The register unit 321 has multiple registers accessible by the host device. For example, the host device can access the data register of the register unit 321 via the host interface circuit 35 by outputting a chip select signal XHCS and a serial clock signal HSCLK to the terminal THCS and the terminal THCK, respectively, and outputting a serial data signal HSDO, which is a command to read the three-axis output data, to the terminal THDI. The processing circuit 32 counts the number of updates to the data register for the three-axis output data and writes the counted number of updates to the update count register of the register unit 321. The host device can identify the ordinal number of the three-axis output data by reading the number of updates held in the update count register along with the three-axis output data.

[0037] The interrupt controller 34 accepts various interrupt requests. The interrupt controller 34 then outputs signals to the processing circuit 32 informing the processing circuit 32 of the interrupt request, interrupt level, and vector number according to the priority and interrupt level. The external synchronization signal EXSYC is input to the interrupt controller 34 via the terminal TSYC as one of the interrupt request signals, and when an interrupt request by the external synchronization signal EXSYC is accepted, the corresponding interrupt processing is executed.

[0038] 3 to 6 are diagrams illustrating an example of the structure of the inertial sensor module 1 of this embodiment. FIG. 3 is a plan view of the inertial sensor module 1. FIG. 4 is a cross-sectional view of the inertial sensor module 1 taken along line AA in FIG. 3. FIG. 5 is a plan view of the first inertial sensor 10. FIG. 6 is a plan view of the second inertial sensor 20. Note that, for convenience of explaining the internal configuration of the inertial sensor module 1, FIG. 3 illustrates a state in which the top plate portion 3A of the metal cap 3 is removed. Also, for convenience of explaining the internal configuration of the first inertial sensor 10, FIG. 5 omits components other than the sensor element 11 and the processing circuit 12. Similarly, for convenience of explaining the internal configuration of the second inertial sensor 20, FIG. 6 omits components other than the first sensor element 21, the second sensor element 22, the third sensor element 23, and the processing circuit 27. Note that the dimensional proportions of the components in each drawing are different from the actual proportions.

[0039] In the following description, the three mutually orthogonal axes will be referred to as the X-axis, Y-axis, and Z-axis. The direction along the X-axis will be referred to as the "X-direction," the direction along the Y-axis as the "Y-direction," and the direction along the Z-axis as the "Z-direction," with the arrows indicating the positive direction. The positive Z-direction will be referred to as "up" or "upward," and the negative Z-direction will be referred to as "down" or "downward." In addition, in a plan view from the Z-direction, the surface on the positive Z-direction side will be referred to as the top surface, and the opposite surface on the negative Z-direction side will be referred to as the bottom surface. The Z-axis is an example of the first axis, the X-axis is an example of the second axis, and the Y-axis is an example of the third axis.

[0040] As shown in Figures 3 and 4, the inertial sensor module 1 includes a printed circuit board 2, a metal cap 3 adhered to the main surface 2A, which is the upper surface of the printed circuit board 2, a first inertial sensor 10 and a second inertial sensor 20 provided on the main surface 2A of the printed circuit board 2 and housed between the main surface 2A and the metal cap 3, an arithmetic circuit 30 which is an integrated circuit device mounted on the lower surface 2B of the printed circuit board 2, and a plurality of lead terminals 4 electrically connected to the lower surface 2B of the printed circuit board 2.

[0041] The printed circuit board 2 has a rectangular plate shape in plan view from the Z direction perpendicular to the main surface 2A of the printed circuit board 2. For example, a ceramic substrate or a glass epoxy substrate can be used as the printed circuit board 2. Note that wiring formed on the printed circuit board 2 is not shown in Figures 3 and 4.

[0042] 3 and 4, a metal cap 3 is adhered to a main surface 2A of the printed circuit board 2 via an adhesive member (not shown). The metal cap 3 has a top plate portion 3A and a side wall 3B extending downward from the outer periphery of the top plate portion 3A, and has a rectangular shape that is approximately similar to the shape of the printed circuit board 2 when viewed from above in the Z direction. The metal cap 3 may be made of, for example, 42 alloy, an iron-nickel alloy.

[0043] A first inertial sensor 10 and a second inertial sensor 20 are provided on a main surface 2A of the printed circuit board 2. A metal cap 3 is adhered to the main surface 2A of the printed circuit board 2, so that the first inertial sensor 10 and the second inertial sensor 20 are housed between the main surface 2A of the printed circuit board 2 and the metal cap 3. In this manner, in this embodiment, the first inertial sensor 10 and the second inertial sensor 20 are configured as separate bodies.

[0044] 3 and 4, an arithmetic circuit 30, which is an integrated circuit device, is mounted on the lower surface 2B of the printed circuit board 2. The arithmetic circuit 30 is electrically connected to the first inertial sensor 10 and the second inertial sensor 20 via wiring (not shown) provided on the printed circuit board 2. The arithmetic circuit 30 is configured, for example, by molding a bare chip, which is a semiconductor chip.

[0045] In addition, external connection terminals 5 electrically connected to the arithmetic circuit 30 via wiring (not shown) are provided on the lower surface 2B of the printed circuit board 2. Furthermore, a plurality of lead terminals 4 are provided on the lower surface 2B of the printed circuit board 2 along the four sides of the printed circuit board 2. The lead terminals 4 are electrically connected to the external connection terminals 5 via a conductive joining member such as solder (not shown).

[0046] The first inertial sensor 10 is a single-axis inertial sensor that detects a physical quantity about a desired detection axis among the three axes, X-axis, Y-axis, and Z-axis, with high accuracy. Here, the first inertial sensor 10 detects an angular velocity about the Z-axis. As shown in FIG. 5 , the first inertial sensor 10 has a rectangular shape when viewed from above in the Z direction. The first inertial sensor 10 includes a printed circuit board 101, a sensor element 11 mounted on the printed circuit board 101 and having the first axis as its detection axis, a processing circuit 12 that is an integrated circuit device mounted on the printed circuit board 101, and a package 102 that houses the printed circuit board 101 on which the sensor element 11 and the processing circuit 12 are mounted. The sensor element 11 detects an angular velocity about the first axis, i.e., the Z-axis. The sensor element 11 and the processing circuit 12 are electrically connected. Note that, in FIG. 5 , wiring formed on the top surface of the package 102 and the printed circuit board 101 is not shown.

[0047] The second inertial sensor 20 is a triaxial inertial sensor that detects physical quantities using three axes, namely, the X-axis, the Y-axis, and the Z-axis, as detection axes. Here, the second inertial sensor 20 detects angular velocities around the X-axis, the Y-axis, and the Z-axis. As shown in FIG. 6 , the second inertial sensor 20 has a rectangular shape in a plan view from the Z direction. The second inertial sensor 20 includes a silicon substrate 201, a first sensor element 21 formed on the silicon substrate 201 and having a first axis as its detection axis, a second sensor element 22 formed on the silicon substrate 201 and having a second axis as its detection axis, a third sensor element 23 formed on the silicon substrate 201 and having a third axis as its detection axis, a processing circuit 27 that is an integrated circuit formed on the silicon substrate 201, and a package 202 that houses the silicon substrate 201 on which the first sensor element 21, the second sensor element 22, the third sensor element 23, and the processing circuit 27 are formed. The first sensor element 21 detects an angular velocity around the Z-axis, which is the first axis. The second sensor element 22 detects an angular velocity around the X-axis, which is the second axis. The third sensor element 23 detects an angular velocity around the Y-axis, which is the third axis. The first sensor element 21, the second sensor element 22, and the third sensor element 23 are each electrically connected to the processing circuit 27. Note that in FIG. 6, wiring formed on the top surface of the package 202 and on the silicon substrate 201 is omitted from the illustration.

[0048] In this embodiment, the detection accuracy of the first inertial sensor 10 is higher than that of the second inertial sensor 20. For example, the sensor element 11 of the first inertial sensor 10 is an element made of quartz, whereas the first sensor element 21, the second sensor element 22, and the third sensor element 23 of the second inertial sensor 20 are elements formed from a silicon substrate 201 using MEMS technology. The first inertial sensor 10 having such a sensor element 11 has high frequency temperature characteristics and frequency stability, and low noise and jitter. Therefore, compared to the second inertial sensor 20 having the first sensor element 21, the second sensor element 22, and the third sensor element 23, the first inertial sensor 10 is more expensive but has higher detection accuracy.

[0049] In this embodiment, for the angular velocity around the Z axis, which requires particularly high detection accuracy, a detection signal detected by the first inertial sensor 10, which has higher detection accuracy than the second inertial sensor 20, is used, and for the angular velocity around the X axis and the Y axis, which may require relatively lower detection accuracy compared to the angular velocity around the Z axis, a detection signal detected by the second inertial sensor 20, which is less expensive but has lower detection accuracy than the first inertial sensor 10, is used.

[0050] However, due to differences in materials and structures between the sensor element 11 and the first sensor element 21, the range in which linearity of output relative to input is satisfied may be wider for the detection signal of angular velocity around the Z axis output from the second inertial sensor 20 than for the detection signal of angular velocity around the Z axis output from the first inertial sensor 10.

[0051] Fig. 7 is a diagram showing an example of the input / output characteristics of the sensor element 11, which is a quartz element, and the first sensor element 21, which is a silicon MEMS element. In Fig. 7, the solid line represents the input / output characteristics of the sensor element 11, and the dashed line represents the input / output characteristics of the first sensor element 21. The horizontal axis represents the angular velocity acting on the Z axis, and the vertical axis represents the angular velocities detected by the sensor element 11 and the first sensor element 21. Note that the example in Fig. 7 shows the input / output characteristics after sensitivity correction and offset correction have been performed on the output signals of the sensor element 11 and the first sensor element 21, and the dashed line represents an ideal straight line for input and output.

[0052] In the example of FIG. 7 , the input-output characteristics of sensor element 11 have almost no offset error. Furthermore, the input-output characteristics of sensor element 11 exhibit excellent linearity when the angular velocity acting on the Z axis is in the range of −p1 dps to +p2 dps, but the linearity deteriorates when the angular velocity acting on the Z axis is less than −p1 dps or greater than +p2 dps. Meanwhile, the input-output characteristics of first sensor element 21 exhibit a larger offset error than the input-output characteristics of sensor element 11, but the range in which linearity is satisfied is wider than the input-output characteristics of sensor element 11. Therefore, the error from the ideal line is smaller in the input-output characteristics of sensor element 11 when the angular velocity acting on the Z axis is in the range of −q1 dps to +q2 dps, but is smaller in the input-output characteristics of first sensor element 21 when the angular velocity acting on the Z axis is less than −q1 dps or greater than +q2 dps.

[0053] Therefore, when the angular velocity around the Z axis is between −q1 dps and +q2 dps, the arithmetic circuit 30 selects and outputs the first Z-axis output signal based on the detection signal output from the sensor element 11. When the angular velocity around the Z axis is less than −q1 dps or more than +q2 dps, the arithmetic circuit 30 selects and outputs the second Z-axis output signal based on the detection signal output from the first sensor element 21. That is, depending on the range of rotational motion acting on the Z axis, i.e., the range of angular velocities acting on the Z axis, the arithmetic circuit 30 selects either the first Z-axis output signal or the second Z-axis output signal, whichever has the smaller error from the ideal line. Note that the arithmetic circuit 30 may use either the first Z-axis output signal or the second Z-axis output signal to identify the angular velocity acting on the Z axis. However, it is preferable to use the second Z-axis output signal, which has better linearity over a wider range of input angular velocities.

[0054] As described above, in this embodiment, the arithmetic circuit 30 selects either the second output signal of the Z axis based on the Z axis detection signal output from the first inertial sensor 10 or the second output signal of the Z axis based on the Z axis detection signal output from the second inertial sensor 20, depending on the range of motion acting on the Z axis, and generates three-axis output data including the Z axis output signal, an X axis output signal based on the X axis detection signal output from the second inertial sensor 20, and a Y axis output signal based on the Y axis detection signal output from the second inertial sensor 20, and outputs the data to the host device.

[0055] The first inertial sensor 10, which has high detection accuracy, may be a quartz sensor that detects angular velocity around two or more axes, but in this embodiment, it is configured to detect angular velocity around only one axis in order to reduce costs. Also, the second inertial sensor 20 does not necessarily need to detect angular velocity around the first axis, but silicon MEMS sensors that detect angular velocity around three axes are in high demand and available at low cost, so in this embodiment, it is configured to detect angular velocity around three axes.

[0056] As described above, according to the inertial sensor module 1 of the first embodiment, the detection accuracy of the first inertial sensor 10 is higher than the detection accuracy of the second inertial sensor 20, and therefore high detection accuracy for the first axis can be achieved by the arithmetic circuit 30 selecting and outputting the first output signal for the first axis based on the detection signal for the first axis output from the first inertial sensor 10. Furthermore, according to the inertial sensor module 1 of the first embodiment, in a situation where the detection accuracy of the first inertial sensor 10 is significantly reduced, the arithmetic circuit 30 selecting and outputting the second output signal for the first axis based on the detection signal for the first axis output from the second inertial sensor 20 reduces the risk of a significant reduction in detection accuracy for the first axis.

[0057] In particular, in the inertial sensor module 1 of the first embodiment, the arithmetic circuit 30 selects and outputs either the first output signal of the first axis or the second output signal of the first axis depending on the range of motion acting on the first axes of the first inertial sensor 10 and the second inertial sensor 20. Therefore, according to the inertial sensor module 1 of the first embodiment, in a range of motion in which the detection accuracy of the first inertial sensor 10 is high, the arithmetic circuit 30 selects and outputs the first output signal of the first axis, thereby realizing high detection accuracy for the first axis, and in a range of motion in which the detection accuracy of the first inertial sensor 10 is significantly reduced, the arithmetic circuit 30 selects and outputs the second output signal of the first axis, thereby reducing the risk of a significant reduction in detection accuracy for the first axis.

[0058] Furthermore, according to the inertial sensor module 1 of the first embodiment, the second inertial sensor 20 is a silicon MEMS sensor, so the manufacturing cost of the second inertial sensor 20 is reduced, and a low cost is achieved.

[0059] Furthermore, according to the inertial sensor module 1 of the first embodiment, the first inertial sensor 10 has the first axis as its detection axis, and the second inertial sensor 20 has the first, second, and third axes as its detection axes, so that output signals for three axes can be obtained, with the accuracy of the output signal for the first axis being higher than the accuracy of the output signals for the second and third axes. Therefore, by using the inertial sensor module 1 of the first embodiment, it is possible to realize a system that requires higher detection accuracy for one specific axis than for the other two axes, while suppressing unnecessary costs.

[0060] 2. Second embodiment In the following, in the second embodiment, the same components as those in the first embodiment are given the same reference numerals, and explanations that overlap with those in the first embodiment are omitted or simplified, and differences from the first embodiment are mainly described.

[0061] The functional configuration of the inertial sensor module 1 of the second embodiment is the same as that of Fig. 1, and therefore not shown. The structure of the inertial sensor module 1 of the second embodiment is the same as that of Figs. 3 to 6, and therefore not shown. The inertial sensor module 1 of the second embodiment differs from the first embodiment in the function and configuration of the arithmetic circuit 30.

[0062] In the second embodiment, the arithmetic circuit 30 selects and outputs, depending on the temperature, either a first output signal for the first axis based on the detection signal for the first axis output from the first inertial sensor 10 or a second output signal for the first axis based on the detection signal for the first axis output from the second inertial sensor 20. For example, the arithmetic circuit 30 may detect the temperature based on a temperature signal TMPO input from the terminal TSEN, and select the first output signal for the first axis if the temperature is within a predetermined range, or select the second output signal for the first axis if the temperature is not within the predetermined range.

[0063] Fig. 8 is a diagram showing an example of the configuration of the arithmetic circuit 30 included in the inertial sensor module 1 of the second embodiment. As shown in Fig. 8, the arithmetic circuit 30 of the second embodiment includes, similarly to the first embodiment, a digital interface circuit 31, a processing circuit 32, a signal processing circuit 33, an interrupt controller 34, and a host interface circuit 35. The functions of the digital interface circuit 31, the signal processing circuit 33, the interrupt controller 34, and the host interface circuit 35 are the same as those of the first embodiment, and therefore description thereof will be omitted.

[0064] In this embodiment, similar to the first embodiment, the processing circuit 32 includes a register unit 321 and an output selection circuit 322. The output selection circuit 322 receives a temperature signal TMPO from the terminal TSEN, detects the temperature based on the temperature signal TMPO, and selects, depending on the temperature, either a first output signal for the first axis based on the detection signal for the first axis included in the first detection data SD1 or a second output signal for the first axis based on the detection signal for the first axis included in the second detection data SD2.

[0065] In this embodiment, the correction circuit 332 of the signal processing circuit 33 also performs temperature correction calculations on the first detection data SD1 and the second detection data SD2 based on the temperature signal TMPO and the temperature correction table. However, to improve detection accuracy within a predetermined temperature range, the temperature table is created in advance so that the error of the first output signal of the first axis relative to its true value is extremely small within the predetermined temperature range. Therefore, if the temperature significantly deviates from the predetermined temperature range, the error of the first output signal of the first axis will be large. Therefore, if the temperature table is created so that the error of the second output signal of the first axis is smaller than the maximum error of the first output signal of the first axis throughout the entire target temperature range, the second output signal of the first axis will have a smaller error than the first output signal of the first axis even if the temperature significantly deviates from the predetermined temperature range.

[0066] FIG. 9 is a diagram showing an example of the temperature characteristics of the sensor element 11, which is a quartz element, and the first sensor element 21, which is a silicon MEMS element, after temperature correction. In FIG. 9, the solid line represents the temperature characteristics of the sensor element 11 after temperature correction, and the dashed-dotted line represents the temperature characteristics of the first sensor element 21 after temperature correction. The horizontal axis represents temperature, and the vertical axis represents the angular velocity around the first axis detected by the sensor element 11 and the first sensor element 21 after temperature correction. Note that the example in FIG. 9 shows the temperature characteristics when the angular velocity acting on the first axis is zero. In the example in FIG. 9, the temperature characteristics of the sensor element 11 after temperature correction show that the first output signal of the first axis has almost zero error within the predetermined temperature range TA, but the error becomes large in a temperature range TB outside the temperature range TA. On the other hand, the temperature characteristics of the first sensor element 21 show that the second output signal of the first axis has a large error within the temperature range TA, but the error is kept within a certain range across the temperature ranges TA and TB. Therefore, the output selection circuit 322 selects the first output signal of the first axis when the temperature determined based on the temperature signal TMPO is within the temperature range TA, and selects the second output signal of the first axis when the temperature is within the temperature range TB.

[0067] Alternatively, the output selection circuit 322 may select either the first output signal of the first axis or the second output signal of the first axis depending on the range of motion acting on the first axis and the temperature. In this case, for example, if the error of the first output signal of the first axis with respect to the ideal line when the motion acting on the first axis is in a first range of motion is smaller than the error of the second output signal of the first axis, and the error of the first output signal of the first axis is approximately zero when the temperature is in a first temperature range, the output selection circuit 322 may select the first output signal of the first axis when the motion acting on the first axis is in the first range of motion and the temperature is in the first temperature range, and may select the second output signal of the first axis otherwise. For example, in the example of FIG. 7, the first range of motion is the range in which the angular velocity is greater than or equal to -q1 and less than or equal to +q2, and the first temperature range is the temperature range TA in the example of FIG. 9.

[0068] When the output selection circuit 322 selects the first output signal of the first axis, it generates three-axis output data including the first output signal of the first axis, the output signal of the second axis, and the output signal of the third axis that are synchronized with each other, and stores the data in the data register of the register unit 321. When the output selection circuit 322 selects the second output signal of the first axis, it generates three-axis output data including the second output signal of the first axis, the output signal of the second axis, and the output signal of the third axis that are synchronized with each other, and stores the data in the data register of the register unit 321. The host device can access the data register of the register unit 321 via the host interface circuit 35 and read the three-axis output data that is output from the terminal THDO as a serial data signal HSDI.

[0069] The other functions of the processing circuit 32 are the same as those in the first embodiment, and therefore the description thereof will be omitted.

[0070] The inertial sensor module 1 of the second embodiment described above has the same effects as the inertial sensor module 1 of the first embodiment.

[0071] Furthermore, in the inertial sensor module 1 of the second embodiment, the arithmetic circuit 30 selects and outputs either the first output signal of the first axis or the second output signal of the first axis depending on the temperature. Therefore, according to the inertial sensor module 1 of the second embodiment, at temperatures at which the detection accuracy of the first inertial sensor 10 is high, the arithmetic circuit 30 selects and outputs the first output signal of the first axis, thereby realizing high detection accuracy for the first axis, and at temperatures at which the detection accuracy of the first inertial sensor 10 significantly decreases, the arithmetic circuit 30 selects and outputs the second output signal of the first axis, thereby reducing the risk of a significant decrease in detection accuracy for the first axis.

[0072] 3. Third embodiment Hereinafter, for the third embodiment, components similar to those in the first or second embodiment will be given the same symbols, explanations that overlap with those in the first or second embodiment will be omitted or simplified, and the following will mainly describe the differences from the first and second embodiments.

[0073] Fig. 10 is a diagram showing an example of the functional configuration of the inertial sensor module 1 of the third embodiment. As shown in Fig. 10, the inertial sensor module 1 of the third embodiment includes a first inertial sensor 10, a second inertial sensor 20, an arithmetic circuit 30, and a temperature sensor 40, similar to the first or second embodiment. Note that the inertial sensor module 1 may be configured such that some of the components shown in Fig. 10 are omitted or modified, or other components are added.

[0074] In the third embodiment, the configuration of the second inertial sensor 20 is different from that of the first and second embodiments. In the third embodiment, the second inertial sensor 20 is a sensor that uses the first axis, the second axis, and the third axis as detection axes, and further uses the fourth axis, the fifth axis, and the sixth axis as detection axes, respectively.

[0075] 10 , the second inertial sensor 20 includes a first sensor element 21, a second sensor element 22, a third sensor element 23, a fourth sensor element 24, a fifth sensor element 25, a sixth sensor element 26, and a processing circuit 27. The second inertial sensor 20 is a device in which a silicon substrate on which the first sensor element 21, the second sensor element 22, the third sensor element 23, the fourth sensor element 24, the fifth sensor element 25, the sixth sensor element 26, and the processing circuit 27 are formed is housed in a package. The configurations and functions of the first sensor element 21, the second sensor element 22, and the third sensor element 23 are similar to those of the first or second embodiment, and therefore description thereof will be omitted.

[0076] The fourth sensor element 24 is a sensor element that detects a physical quantity using the fourth axis as its detection axis. The fifth sensor element 25 is a sensor element that detects a physical quantity using a fifth axis, which is different from the fourth axis, as its detection axis. The sixth sensor element 26 is a sensor element that detects a physical quantity using a sixth axis, which is different from the fourth and fifth axes, as its detection axis. The physical quantities detected by the fourth sensor element 24, the fifth sensor element 25, and the sixth sensor element 26 may be the same or different from each other. Furthermore, the fourth axis, the fifth axis, and the sixth axis may be the same as or different from the first axis, the second axis, and the third axis, respectively. For example, the first sensor element 21 may detect an angular velocity around the Z axis, the second sensor element 22 may detect an angular velocity around the X axis, the third sensor element 23 may detect an angular velocity around the Y axis, the fourth sensor element 24 may detect acceleration in the Z axis direction, the fifth sensor element 25 may detect acceleration in the X axis direction, and the sixth sensor element 26 may detect acceleration in the Y axis direction.

[0077] The processing circuit 27 performs a physical quantity detection process on the signals output from the first sensor element 21, the second sensor element 22, the third sensor element 23, the fourth sensor element 24, the fifth sensor element 25, and the sixth sensor element 26, respectively, and outputs second detection data SD2 obtained by the detection process. The processing circuit 27 includes a detection circuit 271 that performs a physical quantity detection process on the signals output from the first sensor element 21, the second sensor element 22, the third sensor element 23, the fourth sensor element 24, the fifth sensor element 25, and the sixth sensor element 26, respectively, and an interface circuit 272 that outputs the second detection data SD2 obtained by the detection process of the detection circuit 271. For example, the detection circuit 271 may include six amplifier circuits that amplify the signals output from the first sensor element 21, the second sensor element 22, the third sensor element 23, the fourth sensor element 24, the fifth sensor element 25, and the sixth sensor element 26, six detector circuits that detect the output signals of each amplifier circuit, six gain adjustment circuits that adjust the voltage of the output signal of each detector circuit, six offset adjustment circuits that adjust the offset of the output signal of each gain adjustment circuit, and an A / D conversion circuit that converts the output signal of each offset adjustment circuit into a digital signal in a time-division manner. The interface circuit 272 receives the digital signal output from the A / D conversion circuit of the detection circuit 271 as second detection data SD2 in accordance with the timing of the external synchronization signal EXSYC input from the terminal TCS2, and outputs the second detection data SD2 in response to a read command from the arithmetic circuit 30. The second detection data SD2 includes a detection signal of the first axis by the first sensor element 21, a detection signal of the second axis by the second sensor element 22, a detection signal of the third axis by the third sensor element 23, a detection signal of the fourth axis by the fourth sensor element 24, a detection signal of the fifth axis by the fifth sensor element 25, and a detection signal of the sixth axis by the sixth sensor element 26.

[0078] The arithmetic circuit 30 performs arithmetic processing on the first detection data SD1 to generate a first-axis output signal based on the first-axis detection signal output from the first inertial sensor 10. Furthermore, the arithmetic circuit 30 performs arithmetic processing on the second detection data SD2 to generate a first-axis output signal based on the second-axis detection signal output from the second inertial sensor 20, a second-axis output signal based on the second-axis detection signal output from the second inertial sensor 20, a third-axis output signal based on the third-axis detection signal output from the second inertial sensor 20, a fourth-axis output signal based on the fourth-axis detection signal output from the second inertial sensor 20, a fifth-axis output signal based on the fifth-axis detection signal output from the second inertial sensor 20, and a sixth-axis output signal based on the sixth-axis detection signal output from the second inertial sensor 20. The arithmetic circuit 30 then selects either the first output signal of the first axis or the second output signal of the first axis.

[0079] In this embodiment, similar to the first embodiment, the arithmetic circuit 30 may select and output either the first output signal of the first axis or the second output signal of the first axis depending on the range of motion acting on the first axis of the first inertial sensor 10 and the second inertial sensor 20. Also, similar to the second embodiment, the arithmetic circuit 30 may select and output either the first output signal of the first axis or the second output signal of the first axis depending on the temperature, or may select either the first output signal of the first axis or the second output signal of the first axis depending on the range of motion acting on the first axis and the temperature.

[0080] When the arithmetic circuit 30 selects the first output signal of the first axis, it generates six-axis output data including the first output signal of the first axis, the output signal of the second axis, the output signal of the third axis, the output signal of the fourth axis, the output signal of the fifth axis, and the output signal of the sixth axis that are synchronized with one another. When the arithmetic circuit 30 selects the second output signal of the first axis, it generates six-axis output data including the second output signal of the first axis, the output signal of the second axis, the output signal of the third axis, the output signal of the fourth axis, the output signal of the fifth axis, and the output signal of the sixth axis that are synchronized with one another.

[0081] When the arithmetic circuit 30 completes generation of the 6-axis output data, it outputs a signal DRDY from terminal TR to the host device, indicating that the 6-axis output data is ready. When the host device receives the signal DRDY, it outputs a chip select signal XHCS, a serial clock signal HSCLK, and a serial data signal HSDI, which is a command to read the 6-axis output data, conforming to the SPI communication standard, to the arithmetic circuit 30. The arithmetic circuit 30 performs interface processing according to the SPI communication standard based on the chip select signal XHCS received from terminal THCS, the serial clock signal HSCLK received from terminal THCK, and the serial data signal HSDI received from terminal THDI, and outputs the 6-axis output data to terminal THDO. The 6-axis output data output from terminal THDO of the arithmetic circuit 30 is input to the host device as the serial data signal HSDO.

[0082] Furthermore, similar to the first or second embodiment, the arithmetic circuit 30 may perform correction operations such as filter operations, temperature correction, zero point correction, sensitivity correction, and nonlinearity correction, downsampling operations, and operations to calculate the attitude and position of the inertial sensor module 1 on the first detection data SD1 and the second detection data SD2.

[0083] The configuration example of the arithmetic circuit 30 in the third embodiment is the same as that shown in FIG. 2 or FIG. 8, and therefore its illustration and description will be omitted.

[0084] Fig. 11 is a plan view of the second inertial sensor 20 in the third embodiment. For the convenience of explaining the internal configuration of the second inertial sensor 20, Fig. 11 omits components other than the first sensor element 21, the second sensor element 22, the third sensor element 23, the fourth sensor element 24, the fifth sensor element 25, the sixth sensor element 26, and the processing circuit 27. Note that the dimensional ratios of the components in Fig. 11 differ from the actual ratios.

[0085] The second inertial sensor 20 is, for example, a six-axis inertial sensor that detects angular velocity using the X-axis, Y-axis, and Z-axis as detection axes, and detects acceleration using the X-axis, Y-axis, and Z-axis as detection axes. As shown in Fig. 11, the second inertial sensor 20 has a rectangular outer shape when viewed from a plane in the Z direction. The second inertial sensor 20 includes a silicon substrate 201, a first sensor element 21 formed on the silicon substrate 201 and having a first axis as its detection axis, a second sensor element 22 formed on the silicon substrate 201 and having a second axis as its detection axis, a third sensor element 23 formed on the silicon substrate 201 and having a third axis as its detection axis, a fourth sensor element 24 formed on the silicon substrate 201 and having a fourth axis as its detection axis, a fifth sensor element 25 formed on the silicon substrate 201 and having a fifth axis as its detection axis, a sixth sensor element 26 formed on the silicon substrate 201 and having a sixth axis as its detection axis, a processing circuit 27 which is an integrated circuit formed on the silicon substrate 201, and a package 202 that houses the silicon substrate 201 on which the first sensor element 21, the second sensor element 22, the third sensor element 23, the fourth sensor element 24, the fifth sensor element 25, the sixth sensor element 26, and the processing circuit 27 are formed. The first sensor element 21 detects an angular velocity around the Z-axis, which is the first axis. The second sensor element 22 detects angular velocity around the X-axis, which is the second axis. The third sensor element 23 detects angular velocity around the Y-axis, which is the third axis. The fourth sensor element 24 detects acceleration in the Z-axis direction, which is the fourth axis. The fifth sensor element 25 detects acceleration in the X-axis direction, which is the fifth axis. The sixth sensor element 26 detects acceleration in the Y-axis direction, which is the sixth axis. The first sensor element 21, the second sensor element 22, the third sensor element 23, the fourth sensor element 24, the fifth sensor element 25, and the sixth sensor element 26 are each electrically connected to the processing circuit 27. Note that in FIG. 11, wiring formed on the top surface of the package 202 and on the silicon substrate 201 is omitted from the illustration.

[0086] In the third embodiment, as in the first or second embodiment, the detection accuracy of the first inertial sensor 10 is higher than that of the second inertial sensor 20. For example, the sensor element 11 of the first inertial sensor 10 is an element made of quartz, which has a high Q value and excellent temperature characteristics, whereas the first sensor element 21, the second sensor element 22, the third sensor element 23, the fourth sensor element 24, the fifth sensor element 25, and the sixth sensor element 26 of the second inertial sensor 20 are elements formed from a silicon substrate 201 using MEMS technology. The first inertial sensor 10 having such a sensor element 11 is more expensive but has higher detection accuracy than the second inertial sensor 20 having the first sensor element 21, the second sensor element 22, the third sensor element 23, the fourth sensor element 24, the fifth sensor element 25, and the sixth sensor element 26.

[0087] In this embodiment, for the angular velocity around the Z axis, which requires particularly high detection accuracy, a detection signal detected by the first inertial sensor 10, which has higher detection accuracy than the second inertial sensor 20, is used, and for the angular velocity around the X axis, the angular velocity around the Y axis, the acceleration in the Z axis direction, the acceleration in the X axis direction, and the acceleration in the Y axis direction, which may be detected with relatively lower detection accuracy compared to the angular velocity around the Z axis, a detection signal detected by the second inertial sensor 20, which is less expensive but has lower detection accuracy than the first inertial sensor 10, is used.

[0088] However, for the angular velocity around the Z axis, the detection signal detected by the second inertial sensor 20 is used instead of the detection signal detected by the first inertial sensor 10, depending on the temperature and the range of rotational motion acting on the Z axis. That is, the arithmetic circuit 30 selects, as the output signal of the angular velocity around the Z axis, either a first output signal of the angular velocity around the Z axis based on the detection signal of the angular velocity around the Z axis output from the first inertial sensor 10 or a second output signal of the angular velocity around the Z axis based on the detection signal of the angular velocity around the Z axis output from the second inertial sensor 20, depending on the temperature and the range of rotational motion acting on the Z axis. Then, the arithmetic circuit 30 generates six-axis output data including an output signal of the angular velocity around the Z-axis, an output signal of the angular velocity around the X-axis based on the detection signal of the angular velocity around the X-axis output from the second inertial sensor 20, an output signal of the angular velocity around the Y-axis based on the detection signal of the angular velocity around the Y-axis output from the second inertial sensor 20, an output signal of the acceleration in the Z-axis direction based on the detection signal of the acceleration in the X-axis direction output from the second inertial sensor 20, and an output signal of the acceleration in the Y-axis direction based on the detection signal of the acceleration in the Y-axis direction output from the second inertial sensor 20, and outputs the six-axis output data to the host device.

[0089] The first inertial sensor 10, which has high detection accuracy, may be a quartz sensor that detects angular velocity around two or more axes, but in this embodiment, it is configured to detect angular velocity around only one axis in order to reduce costs. Also, the second inertial sensor 20 does not necessarily need to detect angular velocity around the first axis, but silicon MEMS sensors that detect angular velocity around three axes and acceleration in three-axis directions are in high demand and available at low cost, so in this embodiment, it is configured to detect angular velocity around three axes and acceleration in three-axis directions.

[0090] The inertial sensor module 1 of the third embodiment described above has the same effects as the inertial sensor module 1 of the first or second embodiment.

[0091] Furthermore, according to the inertial sensor module 1 of the third embodiment, the first inertial sensor 10 detects the first axis, and the second inertial sensor 20 detects the first, second, third, fourth, fifth, and sixth axes, so that six-axis output signals can be obtained, with the accuracy of the output signal for the first axis being higher than the accuracy of the output signals for the second, third, fourth, fifth, and sixth axes. Therefore, by using the inertial sensor module 1 of the third embodiment, it is possible to realize a system that requires higher detection accuracy for one specific axis than for the other five axes, while suppressing unnecessary costs.

[0092] 4. Fourth embodiment Hereinafter, for the fourth embodiment, components similar to those of any of the first to third embodiments will be given the same symbols, and explanations that overlap with those of any of the first to third embodiments will be omitted or simplified, and the following will mainly describe the differences from any of the first to third embodiments.

[0093] The functional configuration of the inertial sensor module 1 of the fourth embodiment is the same as that of Fig. 1 or 10, and therefore not shown. Also, the structure of the inertial sensor module 1 of the fourth embodiment is the same as that of Figs. 3 to 6, and therefore not shown. The inertial sensor module 1 of the fourth embodiment differs from the first to third embodiments in the function and configuration of the arithmetic circuit 30.

[0094] In the fourth embodiment, the arithmetic circuit 30 determines whether or not the first inertial sensor 10 and the second inertial sensor 20 are faulty based on the first-axis detection signal output from the first inertial sensor 10 and the first-axis detection signal output from the second inertial sensor 20, and if it determines that the first inertial sensor 10 is faulty, it selects and outputs a second output signal for the first axis based on the first-axis detection signal output from the second inertial sensor 20, and if it determines that the second inertial sensor 20 is faulty, it selects and outputs a first output signal for the first axis based on the first-axis detection signal output from the first inertial sensor 10.

[0095] For example, if the inertial sensor module 1 has the configuration shown in FIG. 10 , and the first inertial sensor 10 detects the angular velocity about the first axis, and the second inertial sensor 20 detects the angular velocities about the first, second, and third axes and the accelerations about the fourth, fifth, and sixth axes, the arithmetic circuit 30 determines whether the inertial sensor module 1 is stationary based on the detection signals of the accelerations about the fourth, fifth, and sixth axes output from the second inertial sensor 20. Specifically, the inertial sensor module 1 is determined to be stationary when the combined acceleration of the accelerations about the fourth, fifth, and sixth axes matches the acceleration of gravity. Alternatively, if the inertial sensor module 1 has the configuration shown in FIG. 1 or 10 , a signal indicating whether the inertial sensor module 1 is stationary may be input from a terminal (not shown) of the inertial sensor module 1, and the arithmetic circuit 30 may determine whether the inertial sensor module 1 is stationary based on the signal.

[0096] Since the angular velocity acting on the first axis is zero while the inertial sensor module 1 is stationary, if the first inertial sensor 10 and the second inertial sensor 20 are not malfunctioning, the voltages of the angular velocity detection signal for the first axis output from the first inertial sensor 10 and the angular velocity detection signal for the first axis output from the second inertial sensor 20 will be within a predetermined range including the reference voltage. Therefore, if the angular velocity detection signal for the first axis output from the first inertial sensor 10 is not within the predetermined range while the inertial sensor module 1 is stationary, the arithmetic circuit 30 determines that the first inertial sensor 10 is malfunctioning and selects and outputs the second output signal for the first axis. Furthermore, if the angular velocity detection signal for the first axis output from the second inertial sensor 20 is not within the predetermined range while the inertial sensor module 1 is stationary, the arithmetic circuit 30 determines that the second inertial sensor 20 is malfunctioning and selects and outputs the first output signal for the first axis.

[0097] Furthermore, if, during a period in which the inertial sensor module 1 is not stationary, the detection signal of the angular velocity about the first axis output from the first inertial sensor 10 falls within a predetermined range and the detection signal of the angular velocity about the first axis output from the second inertial sensor 20 changes beyond the predetermined range, the arithmetic circuit 30 may determine that the first inertial sensor 10 has failed, and select and output the second output signal of the first axis. Similarly, if, during a period in which the inertial sensor module 1 is not stationary, the detection signal of the angular velocity about the first axis output from the first inertial sensor 10 changes beyond a predetermined range and the detection signal of the angular velocity about the first axis output from the second inertial sensor 20 falls within the predetermined range, the arithmetic circuit 30 may determine that the second inertial sensor 20 has failed, and select and output the first output signal of the first axis.

[0098] If the calculation circuit 30 determines that neither the first inertial sensor 10 nor the second inertial sensor 20 is faulty, it selects either the first output signal of the first axis or the second output signal of the first axis depending on at least one of the range of motion and temperature acting on the first axis.

[0099] Fig. 12 is a diagram showing an example of the configuration of the arithmetic circuit 30 included in the inertial sensor module 1 of the fourth embodiment. As shown in Fig. 12, the arithmetic circuit 30 in the fourth embodiment includes, similarly to any of the first to third embodiments, a digital interface circuit 31, a processing circuit 32, a signal processing circuit 33, an interrupt controller 34, and a host interface circuit 35. The functions of the digital interface circuit 31, the signal processing circuit 33, the interrupt controller 34, and the host interface circuit 35 are similar to those of any of the first to third embodiments, and therefore description thereof will be omitted.

[0100] In this embodiment, the processing circuit 32 includes a register unit 321, an output selection circuit 322, and a fault determination circuit 323. The fault determination circuit 323 determines whether or not the first inertial sensor 10 and the second inertial sensor 20 are faulty based on the detection signal for the first axis included in the first detection data SD1 output from the first inertial sensor 10 and the detection signal for the first axis included in the second detection data SD2 output from the second inertial sensor 20. For example, the fault determination circuit 323 determines whether or not the inertial sensor module 1 is stationary based on the detection signals for the fourth, fifth, and sixth axes included in the second detection data SD2 after arithmetic processing by the signal processing circuit 33. Note that the fault determination circuit 323 may also determine whether or not the inertial sensor module 1 is stationary based on the detection signals for the fourth, fifth, and sixth axes included in the second detection data SD2 before arithmetic processing by the signal processing circuit 33. Alternatively, the failure determination circuit 323 may determine whether the inertial sensor module 1 is stationary or not based on a predetermined signal input from outside the inertial sensor module 1.

[0101] Then, during the period when the inertial sensor module 1 is stationary, if the detection signal of the first axis included in the first detection data SD1 is not within a predetermined range, the failure judgment circuit 323 judges that the first inertial sensor 10 is faulty, and if the detection signal of the first axis included in the second detection data SD2 is not within a predetermined range, it judges that the second inertial sensor 20 is faulty.

[0102] When the failure determination circuit 323 determines that the first inertial sensor 10 has failed, the output selection circuit 322 selects the second output signal of the first axis, which is the detection signal of the first axis included in the second detection data SD2. When the failure determination circuit 323 determines that the second inertial sensor 20 has failed, the output selection circuit 322 selects the first output signal of the first axis, which is the detection signal of the first axis included in the first detection data SD1. When the failure determination circuit 323 determines that neither the first inertial sensor 10 nor the second inertial sensor 20 has failed, the output selection circuit 322 selects either the first output signal of the first axis or the second output signal of the first axis depending on at least one of the range of motion and the temperature acting on the first axis.

[0103] Other functions of the processing circuit 32 are the same as those of any of the first to third embodiments, and therefore description thereof will be omitted.

[0104] The inertial sensor module 1 of the fourth embodiment described above has the same effects as the inertial sensor module 1 of any one of the first to third embodiments.

[0105] Furthermore, in the inertial sensor module 1 of the fourth embodiment, the arithmetic circuit 30 determines whether the first inertial sensor 10 and the second inertial sensor 20 have a malfunction, and if it determines that the first inertial sensor 10 has a malfunction, selects and outputs a second output signal for the first axis based on the detection signal for the first axis output from the second inertial sensor 20, and if it determines that the second inertial sensor 20 has a malfunction, selects and outputs a first output signal for the first axis based on the detection signal for the first axis output from the first inertial sensor 10. Therefore, according to the inertial sensor module 1 of the fourth embodiment, it is possible to improve the reliability of the output signal for the first axis.

[0106] 5. Fifth embodiment Below, for the fifth embodiment, components similar to those of any of the first to fourth embodiments are given the same symbols, and explanations that overlap with those of any of the first to fourth embodiments are omitted or simplified, and the following mainly describes the differences from any of the first to fourth embodiments.

[0107] The functional configuration of the inertial sensor module 1 of the fifth embodiment is the same as that of Fig. 1 or 10, and therefore not shown. Also, the structure of the inertial sensor module 1 of the fifth embodiment is the same as that of Figs. 3 to 6, and therefore not shown. The inertial sensor module 1 of the fifth embodiment differs from the first to fourth embodiments in the function and configuration of the arithmetic circuit 30.

[0108] In the fifth embodiment, as in any of the first to fourth embodiments, the detection accuracy of the first inertial sensor 10 is higher than that of the second inertial sensor 20. In the fifth embodiment, the arithmetic circuit 30 receives the first-axis detection signal output from the first inertial sensor 10 and the first-axis detection signal output from the second inertial sensor 20, and corrects the first-axis detection signal output from the first inertial sensor 10 when the magnitude of the first-axis detection signal output from the second inertial sensor 20 is within a predetermined range. For example, when the input / output characteristics of the sensor element 11 and the first sensor element 21 are as shown in FIG. 7, the arithmetic circuit 30 may correct the nonlinearity of the detection signal of the angular velocity about the Z axis output from the first inertial sensor 10 when the angular velocity about the Z axis is in a range smaller than −q1 [dps] or larger than +q2 [dps]. Specifically, an error relative to an ideal straight line of the input / output characteristics of sensor element 11 is calculated in advance, and a nonlinearity correction table that defines the correspondence between the error and the angular velocity acting on the Z axis is created and stored in memory. Then, arithmetic circuit 30 calculates the angular velocity around the Z axis based on the detection signal of the angular velocity around the Z axis output from second inertial sensor 20, and when the angular velocity around the Z axis is in a range smaller than −q1 [dps] or larger than +q2 [dps], identifies an error based on the nonlinearity correction table and corrects the error by subtracting it from the detection signal of the angular velocity around the Z axis output from first inertial sensor 10.

[0109] The arithmetic circuit 30 may select either the first output signal of the first axis or the second output signal of the first axis depending on the temperature, as in the third or fourth embodiment. Furthermore, as in the fourth embodiment, the arithmetic circuit 30 may determine whether or not the first inertial sensor 10 and the second inertial sensor 20 have failed, and if it is determined that the first inertial sensor 10 or the second inertial sensor 20 has failed, select either the first output signal of the first axis or the second output signal of the first axis without correcting the detection signal of the first axis output from the first inertial sensor 10.

[0110] Fig. 13 is a diagram showing an example of the configuration of the arithmetic circuit 30 included in the inertial sensor module 1 of the fifth embodiment. As shown in Fig. 13, the arithmetic circuit 30 in the fifth embodiment includes, similarly to any of the first to fourth embodiments, a digital interface circuit 31, a processing circuit 32, a signal processing circuit 33, an interrupt controller 34, and a host interface circuit 35. The functions of the digital interface circuit 31, the signal processing circuit 33, the interrupt controller 34, and the host interface circuit 35 are similar to those of any of the first to fourth embodiments, and therefore description thereof will be omitted.

[0111] In this embodiment, the processing circuit 32 includes a register unit 321 , an output selection circuit 322 , a failure determination circuit 323 , and a correction circuit 324 .

[0112] The correction circuit 324 receives the first axis detection signal included in the first detection data SD1 output from the first inertial sensor 10 and the first axis detection signal included in the second detection data SD2 output from the second inertial sensor 20, and corrects the first axis detection signal included in the first detection data SD1 when the magnitude of the first axis detection signal included in the second detection data SD2 is within a predetermined range.

[0113] Specifically, when the magnitude of the detection signal for the first axis included in the second detection data SD2 after the arithmetic processing by the signal processing circuit 33 is within a predetermined range, the correction circuit 324 corrects the detection signal for the first axis included in the first detection data SD1 after the arithmetic processing by the signal processing circuit 33. For example, when the magnitude of the detection signal for the first axis included in the second detection data SD2 is within a predetermined range, the correction circuit 324 may correct the nonlinearity of the detection signal for the first axis included in the first detection data SD1.

[0114] When the failure determination circuit 323 determines that the first inertial sensor 10 has failed, the output selection circuit 322 selects the second output signal of the first axis, which is the detection signal of the first axis included in the second detection data SD2. When the failure determination circuit 323 determines that the second inertial sensor 20 has failed, the output selection circuit 322 selects the first output signal of the first axis, which is the corrected detection signal of the first axis included in the first detection data SD1. When the failure determination circuit 323 determines that neither the first inertial sensor 10 nor the second inertial sensor 20 has failed, the output selection circuit 322 may select either the first output signal of the first axis or the second output signal of the first axis depending on the temperature.

[0115] Other functions of the processing circuit 32 are the same as those of any of the first to fourth embodiments, and therefore description thereof will be omitted.

[0116] The inertial sensor module 1 of the fifth embodiment described above has the same effects as the inertial sensor module 1 of any one of the first to fourth embodiments.

[0117] Furthermore, in the inertial sensor module 1 of the fifth embodiment, the arithmetic circuit 30 corrects the detection signal of the first axis output from the first inertial sensor 10 when the magnitude of the detection signal of the first axis output from the second inertial sensor 20 is within a predetermined range. Therefore, according to the inertial sensor module 1 of the fifth embodiment, high detection accuracy for the first axis can be achieved even in a situation where the detection accuracy of the first inertial sensor 10 is reduced.

[0118] 6. Variations The present invention is not limited to the present embodiment, and various modifications are possible within the scope of the present invention.

[0119] In each of the above embodiments, the second inertial sensor 20 detects physical quantities along three or six axes, but may detect physical quantities along one, two, four, five, or seven or more axes. As an example, FIG. 14 shows an example of the functional configuration of an inertial sensor module 1 including a second inertial sensor 20 that detects a physical quantity along one axis. In the example of FIG. 14, the sensor element 11 included in the first inertial sensor 10 and the first sensor element 21 included in the second inertial sensor 20 are both sensor elements that detect the same type of physical quantity using the first axis as the detection axis. As in each of the above embodiments, the detection accuracy of the first inertial sensor 10 is higher than the detection accuracy of the second inertial sensor 20. The arithmetic circuit 30 receives the first-axis detection signal included in the first detection data SD1 output from the first inertial sensor 10 and the first-axis detection signal included in the second detection data SD2 output from the second inertial sensor 20, and selects and outputs either a first output signal for the first axis based on the first-axis detection signal included in the first detection data SD1 or a second output signal for the first axis based on the first-axis detection signal included in the second detection data SD2. For example, the arithmetic circuit 30 may select and output either the first output signal for the first axis or the second output signal for the first axis depending on the range of motion acting on the first axes of the first inertial sensor 10 and the second inertial sensor 20, or may select and output either the first output signal for the first axis or the second output signal for the first axis depending on temperature. The arithmetic circuit 30 may also perform various arithmetic operations on the first detection data SD1 and the second detection data SD2. Specifically, the arithmetic circuit 30 may perform filter calculations, correction calculations such as temperature correction, zero point correction, sensitivity correction, and nonlinearity correction, downsampling calculations, etc. on the first detection data SD1 and the second detection data SD2.

[0120] Alternatively, the arithmetic circuit 30 may receive the detection signal for the first axis included in the first detection data SD1 output from the first inertial sensor 10 and the detection signal for the first axis included in the second detection data SD2 output from the second inertial sensor 20, and correct the detection signal for the first axis included in the first detection data SD1 when the magnitude of the detection signal for the first axis included in the second detection data SD2 is within a predetermined range. For example, the arithmetic circuit 30 may correct the nonlinearity of the detection signal for the first axis included in the first detection data SD1 when the magnitude of the detection signal for the first axis included in the second detection data SD2 is within a predetermined range.

[0121] The arithmetic circuit 30 is configured, for example, as shown in Fig. 2, Fig. 8, Fig. 12 or Fig. 13. According to the inertial sensor module 1 of this modified example, the same effects as those of the inertial sensor module 1 of any one of the first to fifth embodiments described above can be obtained.

[0122] In the fourth embodiment, while the inertial sensor module 1 is stationary, the presence or absence of a malfunction in the first inertial sensor 10 and the presence or absence of a malfunction in the second inertial sensor 20 is determined based on the first-axis detection signal output from the first inertial sensor 10 and the first-axis detection signal output from the second inertial sensor 20. However, the malfunction determination method is not limited to this. For example, the inertial sensor module 1 may further include a third inertial sensor that detects a physical quantity of the first axis, and the arithmetic circuit 30 may determine the presence or absence of a malfunction in the first inertial sensor 10 and the second inertial sensor 20 by majority logic based on the first-axis detection signal output from the first inertial sensor 10, the first-axis detection signal output from the second inertial sensor 20, and the first-axis detection signal output from the third inertial sensor. For example, the calculation circuit 30 may determine that the first inertial sensor 10 is faulty if the difference between the first-axis detection signal output from the second inertial sensor 20 and the first-axis detection signal output from the third inertial sensor is within a predetermined range, and the difference between the first-axis detection signal output from the first inertial sensor 10 and the first-axis detection signal output from the second inertial sensor 20, or the difference between the first-axis detection signal output from the first inertial sensor 10 and the first-axis detection signal output from the third inertial sensor, exceeds a predetermined range. In addition, the arithmetic circuit 30 may determine that the second inertial sensor 20 is faulty if the difference between the first-axis detection signal output from the first inertial sensor 10 and the first-axis detection signal output from the third inertial sensor is within a predetermined range, and the difference between the first-axis detection signal output from the first inertial sensor 10 and the first-axis detection signal output from the second inertial sensor 20 or the difference between the first-axis detection signal output from the second inertial sensor 20 and the first-axis detection signal output from the third inertial sensor exceeds a predetermined range.

[0123] In addition, in each of the above embodiments, the inertial sensor module 1 includes a first inertial sensor 10 with relatively high detection accuracy and a second inertial sensor 20 with relatively low detection accuracy. Alternatively, the inertial sensor module 1 may further include a third inertial sensor with the same detection accuracy as the first inertial sensor 10, in addition to the first inertial sensor 10 and the second inertial sensor 20. The third inertial sensor may have the same structure as the first inertial sensor 10, for example. The arithmetic circuit 30 may then average the first-axis detection signal output from the first inertial sensor 10 and the first-axis detection signal output from the third inertial sensor to generate the first-axis output signal. This averaging allows the first-axis output signal to be obtained with reduced noise. In addition, the arithmetic circuit 30 may determine, based on the first axis detection signal output from the first inertial sensor 10, the first axis detection signal output from the second inertial sensor 20, and the first axis detection signal output from the third inertial sensor, for example by majority logic, whether or not there is a possibility that the first inertial sensor 10, the second inertial sensor 20, and the third inertial sensor are each malfunctioning.

[0124] Alternatively, the inertial sensor module 1 may further include a third inertial sensor with the same detection accuracy as the second inertial sensor 20, in addition to the first inertial sensor 10 and the second inertial sensor 20. The third inertial sensor may, for example, be an inertial sensor with the same structure as the second inertial sensor 20. The arithmetic circuit 30 may then average the detection signals for each axis other than the first axis output from the second inertial sensor 20 and the detection signals for each axis other than the first axis output from the third inertial sensor to generate output signals for each axis other than the first axis. This averaging results in output signals for each axis other than the first axis with reduced noise. The arithmetic circuit 30 may also determine, by majority logic, whether or not each of the first inertial sensor 10, the second inertial sensor 20, and the third inertial sensor is likely to be faulty, based on the detection signals for the first axis output from the first inertial sensor 10, the detection signals for the first axis output from the second inertial sensor 20, and the detection signals for the first axis output from the third inertial sensor. In addition, the calculation circuit 30 may determine, based on the detection signals of each axis other than the first axis output from the second inertial sensor 20 and the detection signals of each axis other than the first axis output from the third inertial sensor, for example by majority logic, whether or not there is a possibility that the second inertial sensor 20 or the third inertial sensor is malfunctioning.

[0125] Alternatively, the inertial sensor module 1 may further include a third inertial sensor with the same detection accuracy as the first inertial sensor 10 and a fourth inertial sensor with the same detection accuracy as the second inertial sensor 20. The third inertial sensor may be, for example, an inertial sensor with the same structure as the first inertial sensor 10, and the fourth inertial sensor may be, for example, an inertial sensor with the same structure as the second inertial sensor 20. The arithmetic circuit 30 may then average the detection signal for the first axis output from the first inertial sensor 10 and the detection signal for the first axis output from the third inertial sensor to generate an output signal for the first axis, and may also average the detection signals for the axes other than the first axis output from the second inertial sensor 20 and the detection signals for the axes other than the first axis output from the fourth inertial sensor to generate output signals for the axes other than the first axis. This averaging allows output signals for each axis with reduced noise to be obtained. The arithmetic circuit 30 may determine, for example, by majority logic, whether or not each of the first inertial sensor 10, the second inertial sensor 20, the third inertial sensor, and the fourth inertial sensor is likely to have malfunctioned, based on the first-axis detection signal output from the first inertial sensor 10, the first-axis detection signal output from the second inertial sensor 20, the first-axis detection signal output from the third inertial sensor, and the first-axis detection signal output from the fourth inertial sensor.The arithmetic circuit 30 may determine, for example, by majority logic, whether or not the second inertial sensor 20 or the fourth inertial sensor is likely to have malfunctioned, based on the detection signals for each axis other than the first axis output from the second inertial sensor 20 and the detection signals for each axis other than the first axis output from the fourth inertial sensor.

[0126] In addition, in each of the above embodiments, an example has been given in which the relatively high-accuracy first inertial sensor 10 is a quartz sensor and the relatively low-accuracy second inertial sensor 20 is a silicon MEMS sensor, but this is not limiting. For example, the relatively high-accuracy first inertial sensor 10 may be a FOG sensor and the relatively low-accuracy second inertial sensor 20 may be a silicon MEMS sensor. FOG is an abbreviation for Fiber Optic Gyroscope.

[0127] The above-described embodiment and modifications are merely examples, and the present invention is not limited to these. For example, the embodiments and modifications can be combined as appropriate.

[0128] The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations with the same functions, methods, and results, or configurations with the same purpose and effects). The present invention also includes configurations that replace non-essential parts of the configurations described in the embodiments. The present invention also includes configurations that achieve the same effects as the configurations described in the embodiments or that can achieve the same purpose. The present invention also includes configurations that add publicly known technology to the configurations described in the embodiments.

[0129] The following can be derived from the above-described embodiment and modifications.

[0130] One aspect of the inertial sensor module is a first inertial sensor having a first axis as a detection axis; a second inertial sensor having the first axis as a detection axis; an arithmetic circuit; Equipped with the detection accuracy of the first inertial sensor is higher than the detection accuracy of the second inertial sensor; The arithmetic circuit receives the detection signal of the first axis output from the first inertial sensor and the detection signal of the first axis output from the second inertial sensor, and selects and outputs either a first output signal based on the detection signal of the first axis output from the first inertial sensor or a second output signal based on the detection signal of the first axis output from the second inertial sensor.

[0131] According to this inertial sensor module, the detection accuracy of the first inertial sensor having the first axis as its detection axis is higher than the detection accuracy of the second inertial sensor having the first axis as its detection axis, and therefore high detection accuracy for the first axis can be achieved by selecting and outputting a first output signal based on the detection signal for the first axis output from the first inertial sensor. Furthermore, according to this inertial sensor module, in a situation where the detection accuracy of the first inertial sensor is significantly reduced, the risk of a significant reduction in detection accuracy for the first axis is reduced by selecting and outputting a second output signal based on the detection signal for the first axis output from the second inertial sensor.

[0132] In one aspect of the inertial sensor module, The arithmetic circuit may select and output either the first output signal or the second output signal depending on the range of motion acting on the first axis of the first inertial sensor and the second inertial sensor.

[0133] According to this inertial sensor module, high detection accuracy for the first axis is achieved by selecting and outputting the first output signal in the range of movement where the detection accuracy of the first inertial sensor is high, and the risk of a significant decrease in detection accuracy for the first axis is reduced by selecting and outputting the second output signal in the range of movement where the detection accuracy of the first inertial sensor is significantly reduced.

[0134] In one aspect of the inertial sensor module, The arithmetic circuit may determine whether or not the first inertial sensor and the second inertial sensor are faulty based on the detection signal of the first axis output from the first inertial sensor and the detection signal of the first axis output from the second inertial sensor, and may select and output the second output signal if it determines that the first inertial sensor is faulty, or may select and output the first output signal if it determines that the second inertial sensor is faulty.

[0135] According to this inertial sensor module, if the first inertial sensor fails, the second output signal based on the detection signal of the first axis output from the second inertial sensor is selected and output, and if the second inertial sensor fails, the first output signal based on the detection signal of the first axis output from the first inertial sensor is selected and output, thereby improving the reliability of the output signal of the first axis.

[0136] In one aspect of the inertial sensor module, The arithmetic circuit may select and output either the first output signal or the second output signal in accordance with temperature.

[0137] According to this inertial sensor module, high detection accuracy for the first axis is achieved by selecting and outputting the first output signal at temperatures where the detection accuracy of the first inertial sensor is high, and the risk of a significant decrease in detection accuracy for the first axis is reduced by selecting and outputting the second output signal at temperatures where the detection accuracy of the first inertial sensor is significantly reduced.

[0138] One aspect of the inertial sensor module is a first inertial sensor having a first axis as a detection axis; a second inertial sensor having the first axis as a detection axis; an arithmetic circuit; Equipped with the detection accuracy of the first inertial sensor is higher than the detection accuracy of the second inertial sensor; The arithmetic circuit receives the detection signal of the first axis output from the first inertial sensor and the detection signal of the first axis output from the second inertial sensor, and corrects the detection signal of the first axis output from the first inertial sensor when the magnitude of the detection signal of the first axis output from the second inertial sensor is within a predetermined range.

[0139] According to this inertial sensor module, the detection signal of the first axis output from the first inertial sensor is corrected when the magnitude of the detection signal of the first axis output from the second inertial sensor is within a predetermined range, thereby achieving high detection accuracy for the first axis even in situations where the detection accuracy of the first inertial sensor is reduced.

[0140] In one aspect of the inertial sensor module, The second inertial sensor Furthermore, the second axis and the third axis may each be set as a detection axis.

[0141] This inertial sensor module provides three-axis output signals, with the accuracy of the output signal from the first axis being higher than the accuracy of the output signals from the second and third axes. Therefore, by using this inertial sensor module, it is possible to realize a system that requires higher detection accuracy for one specific axis than for the other two axes, while reducing unnecessary costs.

[0142] In one aspect of the inertial sensor module, The second inertial sensor Furthermore, the fourth axis, the fifth axis, and the sixth axis may each be set as a detection axis.

[0143] This inertial sensor module provides six-axis output signals, with the accuracy of the output signal from the first axis being higher than the accuracy of the output signals from the second, third, fourth, fifth, and sixth axes. Therefore, by using this inertial sensor module, it is possible to realize a system that requires higher detection accuracy for one specific axis than for the other five axes, while reducing unnecessary costs. [Explanation of symbols]

[0144] 1...inertial sensor module, 2...printed circuit board, 2A...main surface, 2B...bottom surface, 3...metal cap, 3A...top plate portion, 3B...side wall, 4...lead terminal, 5...external connection terminal, 10...first inertial sensor, 11...sensor element, 12...processing circuit, 20...second inertial sensor, 21...first sensor element, 22...second sensor element, 23...third sensor element, 24...fourth sensor element, 25...fifth sensor element, 26...sixth sensor element, 27...processing circuit, 30...arithmetic circuit, 31...digital interface circuit, 32...processing circuit, 33...signal processing circuit, 34...interrupt controller, 35...host interface circuit, 40...temperature sensor, 101...printed circuit board, 102...package, 201...silicon substrate, 202...package, 321...register section, 322...output selection circuit, 323...fault determination circuit, 324...compensation circuit, 331...filter circuit, 332...compensation circuit, 333...attitude calculation circuit, 334...position calculation circuit

Claims

1. a first inertial sensor having a first axis as a detection axis; a second inertial sensor having the first axis as a detection axis; an arithmetic circuit; Equipped with the detection accuracy of the first inertial sensor is higher than the detection accuracy of the second inertial sensor; The arithmetic circuit receives a detection signal of the first axis output from the first inertial sensor and The detection signal of the first axis output from the second inertial sensor is input, and the front a first output signal based on a detection signal of the first axis output from the first inertial sensor; any of second output signals based on the detection signal of the first axis output from the second inertial sensor; An inertial sensor module that selects one of the two and outputs it.

2. The second inertial sensor The inertial sensor module according to claim 1, further comprising a second axis and a third axis as detection axes. Jules.

3. The second inertial sensor 3. The inertial sensor according to claim 2, wherein the fourth axis, the fifth axis, and the sixth axis are each set as a detection axis. Sensor module.

Images