JP6834581B2 - Physical quantity sensors, electronic devices and mobile objects - Google Patents

Description

The present invention relates to physical quantity sensors, electronic devices and mobile objects.

Currently, in various systems and electronic devices, various physical quantity sensors capable of detecting various physical quantities, such as an acceleration sensor for detecting acceleration and a gyro sensor for detecting angular velocity, are widely used. In particular, a physical quantity sensor that converts a physical quantity detection signal (analog signal) into a digital signal by an A / D converter and generates detection data by digital processing is expensive because it can output a digital signal with high noise immunity. It is used for systems and electronic devices that require reliability. In general, digital processing requires a large amount of power consumption, so that reducing power consumption may be an issue. On the other hand, for example, Patent Document 1 discloses a technique for reducing current consumption by controlling ON / OFF of a clock signal input to a DSP according to the state of the DSP. Further, Patent Document 2 discloses a detection device capable of switching the clock frequency of the oscillator and reducing the oscillation frequency in the sensor stop mode to reduce the current consumption.

Japanese Unexamined Patent Publication No. 5-297975 Japanese Unexamined Patent Publication No. 2011-87064

However, when the techniques described in Patent Documents 1 and 2 are applied to the physical quantity sensor, the current consumption can be suppressed by turning off the clock or lowering the frequency while the sensor is stopped, but the current consumption is reduced. There is a problem that it cannot be sensed.

The present invention has been made in view of the above problems, and according to some aspects of the present invention, it is possible to provide a physical quantity sensor capable of reducing current consumption and sensing. .. Further, according to some aspects of the present invention, it is possible to provide an electronic device and a mobile body using the physical quantity sensor.

The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as the following aspects or application examples.

[Application example 1]
The physical quantity sensor according to this application example converts the output signal of the vibration type sensor including the first oscillation circuit, the second oscillation circuit having a higher oscillation frequency than the first oscillation circuit, and the vibration type sensor into a digital signal. The second unit includes an analog / digital converter, a digital processing unit that digitally processes the digital signal based on the clock signal, and a clock output unit that outputs the clock signal to the digital processing unit. The first mode in which the oscillation circuit is stopped and the clock output unit outputs the clock signal based on the output signal of the first oscillation circuit, and the clock output unit is based on the output signal of the second oscillation circuit. It has a second mode for outputting a clock signal.

The vibration type sensor may be, for example, a vibration type angular velocity sensor, a vibration type pressure sensor, a vibration type tilt sensor, or the like.

In the physical quantity sensor according to this application example, the clock signal output to the digital processing unit is a signal based on the output signal of the first oscillation circuit in the first mode, and the oscillation frequency is higher than that of the first oscillation circuit in the second mode. It is a signal based on the output signal of the high second oscillation circuit. Then, in the first mode, the second oscillation circuit is stopped, and the processing of the digital processing unit is performed based on the clock signal having a frequency lower than that of the second mode. Therefore, the digital processing unit uses the output signal of the vibration sensor. On the other hand, processing per unit time can be performed with lower current consumption. Therefore, according to the physical quantity sensor according to the present application example, the current consumption can be reduced in the first mode as compared with the second mode for sensing.

Further, in the second mode, a clock signal having a frequency higher than that in the first mode is output to the digital processing unit, so that the digital processing unit can perform processing at a higher rate than in the first mode. Therefore, according to the physical quantity sensor according to this application example, it is possible to perform sensing in the second mode with a higher resolution than in the first mode.

[Application example 2]
The physical quantity sensor according to the above application example may switch between the first mode and the second mode based on a signal input from the outside.

According to the physical quantity sensor according to this application example, it is possible to freely switch between sensing with low current consumption and sensing with high resolution by an external device during operation.

[Application example 3]
The physical quantity sensor according to the above application example may switch between the first mode and the second mode so that glitches do not occur in the clock signal.

According to the physical quantity sensor according to the present application example, it is possible to prevent the digital processing unit from malfunctioning due to the glitch generated in the clock signal when the first mode and the second mode are switched.

[Application example 4]
In the physical quantity sensor according to the above application example, the digital processing includes a filtering processing, and the digital processing unit may initialize the filtering processing after switching between the first mode and the second mode.

The initialization of the filtering process may be, for example, the initialization of the data to be filtered, or the initialization of the filter coefficient.

According to the physical quantity sensor according to this application example, after the first mode and the second mode are switched, for example, the transient response time of the filtering process is shortened by initializing the data to be filtered. In addition, the filter characteristics can be optimized by initializing the filter coefficient.

[Application example 5]
In the physical quantity sensor according to the application example, the digital processing unit may initialize the filter processing so that the cutoff frequency becomes constant in the first mode and the second mode.

According to the physical quantity sensor according to this application example, the filter characteristics can be kept constant in the first mode and the second mode.

[Application example 6]
The physical quantity sensor according to the above application example further includes a multiplication circuit that multiplies the output signal of the first oscillation circuit, and the output signal of the first oscillation circuit has a frequency higher than that of the output signal of the second oscillation circuit. The deviation is small, and the clock output unit may further have a third mode in which the clock signal is output based on the output signal of the multiplication circuit.

In the physical quantity sensor according to this application example, in the third mode, a clock signal having a higher frequency than the first mode and a smaller frequency deviation than the second mode is output to the digital processing unit. Can perform processing at a higher rate than in the first mode and with higher accuracy than in the second mode. Therefore, according to the physical quantity sensor according to the present application example, it is possible to perform sensing in the third mode with higher resolution than in the first mode and with higher accuracy than in the second mode.

[Application 7]
The electronic device according to this application example includes any of the above physical quantity sensors.

[Application Example 8]
The moving body according to this application example includes any of the above physical quantity sensors.

According to these application examples, since the physical quantity sensor capable of reducing the current consumption and sensing is provided, for example, it is possible to realize a highly reliable electronic device and mobile body.

The functional block diagram of the physical quantity sensor of the 1st Embodiment. Top view of the vibrating piece of the physical quantity detecting element. The figure for demonstrating the operation of a physical quantity detection element. The figure for demonstrating the operation of a physical quantity detection element. The figure which shows the structural example of a drive circuit. The figure which shows the structural example of the detection circuit. The figure which shows the correspondence relationship between the operation mode, ON / OFF of an oscillation circuit and a multiplication circuit, and clock signal CLK. The figure which shows the structural example of the filter used in the filtering process of a DSP. The figure which shows an example of the frequency temperature characteristic of a clock signal CK1 and a clock signal CK2. The figure which shows an example of the waveform of each clock signal and the operation of a digital processing part at the time of switching from a normal mode to a low power mode. The figure which shows an example of the waveform of each clock signal and the operation of a digital processing part at the time of switching from a low power mode to a normal mode. The figure which shows an example of the waveform of each clock signal and the operation of a digital processing part at the time of switching from a normal mode to a high precision mode. The functional block diagram of the physical quantity sensor of the 2nd Embodiment. The figure which shows the configuration example of the posture calculation. The figure which shows the configuration example of the posture calculation apparatus using the physical quantity sensor of 2nd Embodiment. The functional block diagram which shows an example of the structure of the electronic device of this embodiment. The perspective view which shows typically the digital camera which is an example of an electronic device. The figure which shows an example of the moving body of this embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the embodiments described below do not unreasonably limit the content of the present invention described in the claims. Moreover, not all of the configurations described below are essential constituent requirements of the present invention.

In the following, a physical quantity sensor (angular velocity sensor) that detects an angular velocity as a physical quantity will be described as an example.

1. 1. Physical quantity sensor 1-1. 1st Embodiment FIG. 1 is a functional block diagram of a physical quantity sensor of the first embodiment. The physical quantity sensor 1 of the first embodiment is configured to include a physical quantity detection element (sensor element) 2 for outputting an analog signal related to the physical quantity and a signal processing circuit 3.

The physical quantity detecting element 2 has a vibrating piece in which a driving electrode and a detecting electrode are arranged, and in general, the vibrating piece is ensured to be airtight in order to reduce the impedance of the vibrating piece as much as possible and increase the oscillation efficiency. It is sealed in the package. In the present embodiment, the physical quantity detecting element 2 has a so-called double T-shaped vibrating piece having two T-shaped driving vibrating arms.

FIG. 2 is a plan view of a vibrating piece of the physical quantity detecting element 2. The physical quantity detecting element 2 has, for example, a double T-shaped vibrating piece formed of a Z-cut crystal substrate. The vibrating piece made of quartz has an advantage that the detection accuracy of the angular velocity can be improved because the fluctuation of the resonance frequency with respect to the temperature change is extremely small. The X-axis, Y-axis, and Z-axis in FIG. 2 indicate the crystal axis.

As shown in FIG. 2, in the vibrating piece of the physical quantity detecting element 2, the driving vibrating arms 101a and 101b extend from the two driving bases 104a and 104b in the + Y-axis direction and the −Y-axis direction, respectively. Drive electrodes 112 and 113 are formed on the side surface and the upper surface of the drive vibrating arm 101a, respectively, and drive electrodes 113 and 112 are formed on the side surface and the upper surface of the drive vibration arm 101b, respectively. The drive electrodes 112 and 113 are connected to the drive circuit 20 via the DS terminal and the DG terminal of the signal processing circuit 3 shown in FIG. 1, respectively.

The drive bases 104a and 104b are connected to the rectangular detection base 107 via connecting arms 105a and 105b extending in the −X axis direction and the + X axis direction, respectively.

The detection vibrating arm 102 extends from the detection base 107 in the + Y-axis direction and the −Y-axis direction. Detection electrodes 114 and 115 are formed on the upper surface of the detection vibrating arm 102, and a common electrode 116 is formed on the side surface of the detection vibration arm 102. The detection electrodes 114 and 115 are connected to the detection circuit 30 via the S1 terminal and the S2 terminal of the signal processing circuit 3 shown in FIG. 1, respectively. Further, the common electrode 116 is grounded.

When an AC voltage is applied as a drive signal between the drive electrodes 112 and the drive electrodes 113 of the drive vibrating arms 101a and 101b, as shown in FIG. 3, the drive vibrating arms 101a and 101b are shown by the inverse piezoelectric effect as shown by the arrow B. In addition, the tips of the two drive vibration arms 101a and 101b perform bending vibration (excitation vibration) in which the tips of the two driving vibration arms 101a and 101b repeatedly approach and separate from each other.

In this state, when an angular velocity with the Z axis as the rotation axis is applied to the vibrating piece of the physical quantity detecting element 2, the drive vibrating arms 101a and 101b coriolis in the direction perpendicular to both the bending vibration direction of the arrow B and the Z axis. Get the power of. As a result, as shown in FIG. 4, the connecting arms 105a and 105b vibrate as shown by the arrow C. Then, the detection vibrating arm 102 bends and vibrates as shown by the arrow D in conjunction with the vibration (arrow C) of the connecting arms 105a and 105b. The bending vibration of the detected vibrating arm 102 and the bending vibration (exciting vibration) of the driving vibrating arms 101a and 101b due to the Coriolis force are out of phase by 90 °.

By the way, if the magnitude of the vibration energy or the magnitude of the vibration amplitude when the drive vibration arms 101a and 101b perform bending vibration (excitation vibration) is equal to the two drive vibration arms 101a and 101b, the drive vibration arms 101a, The detection vibrating arm 102 does not bend and vibrate when the vibration energy of 101b is balanced and the physical quantity detecting element 2 is not subjected to angular velocity. However, if the vibration energies of the two drive vibration arms 101a and 101b are out of balance, bending vibration is generated in the detection vibration arm 102 even when the physical quantity detection element 2 is not subjected to an angular velocity. This bending vibration is called leakage vibration, which is the bending vibration of arrow D like the vibration based on the Coriolis force, but has the same phase as the drive signal.

Then, due to the piezoelectric effect, AC charges based on these bending vibrations are generated at the detection electrodes 114 and 115 of the detection vibration arm 102. Here, the AC charge generated based on the Coriolis force changes according to the magnitude of the Coriolis force (in other words, the magnitude of the angular velocity applied to the physical quantity detecting element 2). On the other hand, the AC charge generated based on the leakage vibration is constant regardless of the magnitude of the angular velocity applied to the physical quantity detecting element 2.

At the tips of the drive vibrating arms 101a and 101b, a rectangular weight portion 103 wider than the drive vibrating arms 101a and 101b is formed. By forming the weight portion 103 at the tips of the drive vibrating arms 101a and 101b, the Coriolis force can be increased and a desired resonance frequency can be obtained with a relatively short vibrating arm. Similarly, a weight portion 106 wider than the detection vibrating arm 102 is formed at the tip of the detection vibrating arm 102. By forming the weight portion 106 at the tip of the detection vibrating arm 102, the AC charge generated in the detection electrodes 114 and 115 can be increased.

As described above, the physical quantity detecting element 2 detects the AC charge (angular velocity component) based on the Coriolis force and the AC charge (vibration leakage component) based on the leakage vibration of the excitation vibration with the Z axis as the detection axis. Output via 115. The physical quantity detecting element 2 functions as an angular velocity sensor that detects the angular velocity.

Returning to FIG. 1, the signal processing circuit 3 in the present embodiment includes a reference voltage circuit 10, a drive circuit 20, a detection circuit 30, a digital processing unit 40, a clock output unit 50, an oscillation circuit 52, a multiplication circuit 54, a storage unit 60, and the like. It is configured to include an interface circuit 70, and may be, for example, a one-chip integrated circuit (IC). The signal processing circuit 3 in the present embodiment may have a configuration in which some of these elements are omitted or changed, or other elements are added.

The reference voltage circuit 10 generates constant voltages and currents such as reference voltages VR1 and VR2 from the power supply voltage supplied from the VDD terminal of the signal processing circuit 3, and supplies them to the drive circuit 20 and the detection circuit 30.

The drive circuit 20 generates a drive signal DRV for driving (exciting and vibrating) the physical quantity detection element 2 and supplies the drive signal DRV to the drive electrode 112 of the physical quantity detection element 2 via the DS terminal. That is, the drive circuit 20 (an example of the "first oscillation circuit") functions as an oscillation circuit that excites and vibrates the physical quantity detection element 2. Further, in the drive circuit 20, the oscillation current generated in the drive electrode 113 due to the excitation vibration of the physical quantity detection element 2 is input via the DG terminal, and the amplitude of the drive signal DRV is maintained so that the amplitude of the oscillation current is kept constant. Feedback control of the level. Further, the drive circuit 20 generates a detection signal SDET having the same phase as the drive signal DRV, and outputs the detection signal SDET to the detection circuit 30.

FIG. 5 is a diagram showing a configuration example of the drive circuit 20. As shown in FIG. 5, the drive circuit 20 includes an I / V conversion circuit 21, a low-pass filter 22, a high-pass filter 23, a comparator 24, a full-wave rectifier circuit 25, an integrator 26, a comparator 27, and a comparator 28. It is composed of. The drive circuit 20 in the present embodiment may have a configuration in which some of these elements are omitted or changed, or other elements are added.

The I / V conversion circuit 21, the low-pass filter 22, the high-pass filter 23, the comparator 24, the full-wave rectifier circuit 25, the comparator 27, and the comparator 28 operate with reference to the reference voltage VR1 supplied from the reference voltage circuit 10. .. The reference voltage VR1 is an analog ground voltage, which is, for example, a voltage halved from the power supply voltage supplied from the VDD terminal. Further, the integrator 26 operates with reference to the reference voltage VR2 supplied from the reference voltage circuit 10.

The I / V conversion circuit 21 converts the oscillating current generated by the excitation vibration of the physical quantity detection element 2 and input via the DG terminal into an AC voltage signal.

The low-pass filter 22 removes high-frequency components of the output signal of the I / V conversion circuit 21, and the high-pass filter 23 removes low-frequency components (offset, etc.) of the output signal of the low-pass filter 22. A bandpass filter is formed by the lowpass filter 22 and the highpass filter 23, and a signal generated by the excitation vibration of the physical quantity detecting element 2 is passed therethrough.

The comparator 24 compares the voltage of the output signal of the high-pass filter 23 with the reference voltage VR1 to generate a binarized signal. In this binarized signal, the high level voltage is the output voltage of the integrator 26, and the low level voltage is the ground voltage (0V). Then, the output signal of the comparator 24 is supplied to the physical quantity detecting element 2 as a drive signal DRV via the DS terminal. By matching the frequency (drive frequency) of the drive signal DRV with the resonance frequency of the physical quantity detection element 2, the physical quantity detection element 2 can be stably oscillated.

The full-wave rectifier circuit 25 rectifies the output signal of the I / V conversion circuit 21 (full-wave rectification) and outputs a DC signal.

The integrator 26 integrates and outputs the output voltage of the full-wave rectifier circuit 25 with reference to the reference voltage VR2. The output voltage of the integrator 26 decreases as the output voltage of the full-wave rectifier circuit 25 increases (the larger the amplitude of the output signal of the I / V conversion circuit 21). Therefore, the larger the oscillation amplitude, the lower the high-level voltage of the output signal (drive signal DRV) of the comparator 24, and the smaller the oscillation amplitude, the higher the high-level voltage of the output signal (drive signal DRV) of the comparator 24. Therefore, automatic gain control (AGC: Auto Gain Control) is applied so that the oscillation amplitude is kept constant.

The comparator 27 amplifies the voltage of the output signal of the high-pass filter 23 to generate a binarized signal (square wave voltage signal), and outputs it as a detection signal SDET. In this detection signal SDET, the high level voltage is the power supply voltage and the low level voltage is the ground voltage (0V).

The comparator 28 amplifies the voltage of the output signal of the high-pass filter 23 to generate a binarized signal (square wave voltage signal), and outputs it as a clock signal CK2. In this clock signal CK2, the high level voltage is the power supply voltage, and the low level voltage is the ground voltage (0).
V).

Returning to FIG. 1, the detection circuit 30 detects the angular velocity component contained in the AC charge input from the detection electrodes 114 and 115 of the physical quantity detection element 2 via the S1 and S2 terminals, respectively, and corresponds to the magnitude of the angular velocity. Outputs a voltage level analog signal.

FIG. 6 is a diagram showing a configuration example of the detection circuit 30. As shown in FIG. 6, the detection circuit 30 includes a QV amplifier 31, a differential amplifier 32, a variable gain amplifier (PGA: Programmable Gain Amplifier) 33, and a synchronous detection circuit 34. The detection circuit 30 in the present embodiment may have a configuration in which some of these elements are omitted or changed, or other elements are added.

The QV amplifier 31 receives an AC charge (detection current) including an angular velocity component and a vibration leakage component from the detection electrode 114 of the physical quantity detection element 2 via the S1 terminal, and generates a voltage signal corresponding to the AC charge. Let me. Further, in the QV amplifier 31, an AC charge (detection current) including an angular velocity component and a vibration leakage component is input from the detection electrode 115 of the physical quantity detection element 2 via the S2 terminal, and a voltage signal corresponding to the AC charge is input. To generate. The AC charge input from the detection electrode 114 to the QV amplifier 31 and the AC charge input from the detection electrode 114 to the QV amplifier 31 are in opposite phases (phase difference is 180 °), and the two are output from the QV amplifier 31. The signals are also out of phase with each other.

The differential amplifier 32 differentially amplifies the two signals output from the QV amplifier 31 and outputs a single-ended signal.

The variable gain amplifier 33 amplifies or attenuates the signal output from the differential amplifier 32, and outputs a signal having a desired voltage level.

The synchronous detection circuit 34 uses the detection signal SDET output by the drive circuit 20 to synchronously detect the angular velocity component included in the signal (detected signal) output from the variable gain amplifier 33. For example, the synchronous detection circuit 34 outputs the signal output from the variable gain amplifier 33 as it is when the detection signal SDET is at a high level, and outputs the signal output from the variable gain amplifier 33 when the detection signal SDET is at a low level. It can be configured as a circuit that outputs a signal inverted with respect to the reference voltage VR1.

As described above, since the detection circuit 30 detects the angular velocity based on the output signal of the physical quantity detection element 2 in the state where the physical quantity detection element 2 is excited and vibrated by the drive circuit 20, the physical quantity detection element shown in FIG. 2. The configuration including the drive circuit 20 and the detection circuit 30 functions as a vibration type sensor 4 for detecting the angular velocity.

The storage unit 60 has a register 61 and a non-volatile memory 62. Address and data information used in communication with an external device via the interface circuit 70 is set in the register 61. Further, the angular velocity data and the angular data output from the DSP 44 are stored in the register 61.

The non-volatile memory 62 stores various trimming data (adjustment data and correction data) for the drive circuit 20 and the detection circuit 30, and various information for establishing communication with the outside via the interface circuit 70. .. The non-volatile memory 62 can be configured as, for example, a MONOS (Metal Oxide Nitride Oxide Silicon) type memory or an EEPROM (Electrically Erasable Programmable Read-Only Memory).

Further, the non-volatile memory 62 stores mode selection data for selecting the operation mode of the physical quantity sensor 1 (signal processing circuit 3). In the present embodiment, one of a normal mode, a low power mode, and a high precision mode can be selected as the operation mode of the physical quantity sensor 1 (signal processing circuit 3) according to the mode selection data.

When the power of the signal processing circuit 3 is turned on (when the voltage of the VDD terminal rises from 0 V to a desired voltage), various trimming data and mode selection data stored in the non-volatile memory 62 are transferred to the register 61 and held. Will be done. Then, various trimming data held in the register 61 are supplied to the drive circuit 20 and the detection circuit 30, and the mode selection signal MDSEL (normal mode, low power mode, and high precision mode) based on the mode selection data held in the register 61 is supplied. A signal for selecting any one of the above) is supplied to the digital processing unit 40 (DSP44), the clock output unit 50, the oscillation circuit 52, and the multiplication circuit 54.

The interface circuit 70 is electrically connected to an XCS terminal, an SCLK terminal, a MOSI terminal, and a MISO terminal, and is a circuit for communicating with an external device via these terminals. In communication via the interface circuit 70, the external device functions as a master, and the physical quantity sensor 1 (signal processing circuit 3) functions as a slave. Then, the external device writes data to a predetermined address of the register 61 via the interface circuit 70, reads data from the predetermined address of the register 61, and transmits various commands to the signal processing circuit 3 You can control the operation of.

Interface circuit 70, SPI (Serial Peripheral Interface) may function as one of the interface circuits and ^{I 2 C (Inter-Integrated Circuit} ) interface circuit. For example, the interface circuit 70 functions as an SPI interface circuit when the XCS terminal is at a low level, a clock signal is input via the SCLK terminal, a data signal is input via the MOSI terminal, and the data signal is input via the MISO terminal. A data signal is output. The interface circuit 70 may, when XCS pin is high level, and functions as an I 2 ^C interface circuit, a clock signal is input via the SCLK terminal, the data signal is input and output via the MOSI pin.

Communication with an external device via the interface circuit 70 is performed based on various information stored in the register 61. Then, the external device can read the angular velocity data from the predetermined address of the register 61 via the interface circuit 70. As described above, the physical quantity sensor 1 (signal processing circuit 3) is configured to be able to output angular velocity data in response to a request from an external device.

Further, the external device may be able to set (write) mode selection data at a predetermined address of the register 61 via the interface circuit 70. That is, the physical quantity sensor 1 (signal processing circuit 3) may be configured so that the operation mode can be switched in response to a request from an external device.

The oscillation circuit 52 (an example of the “second oscillation circuit”) is an oscillation circuit that outputs the clock signal CK1, and its oscillation frequency (frequency of the clock signal CK1) is the oscillation frequency of the drive circuit 20 (frequency of the clock signal CK2). Higher than. The oscillation circuit 52 may be configured to include, for example, a CR oscillator or a ring oscillator. Further, the oscillation circuit 52 may be configured to include a frequency dividing circuit that divides an output signal of a CR oscillator or the like and outputs a clock signal CK1.

The multiplication circuit 54 outputs a clock signal CK3 obtained by multiplying the clock signal CK2 output by the drive circuit 20. Further, the multiplication circuit 54 outputs a LOCK signal indicating whether or not the frequency of the clock signal CK3 is in a stable state. The multiplication circuit 54 is, for example, a PLL (Phase).
It may be a Locked Loop) circuit or a PLL (Digital Locked Loop) circuit.

In the present embodiment, ON / OFF of the operation of the oscillation circuit 52 and the multiplication circuit 54 is controlled based on the mode selection signal MDSEL. Specifically, as shown in FIG. 7, when the mode selection signal MDSEL indicates the selection of the normal mode, the oscillation circuit 52 is ON (operation) and the multiplication circuit 54 is OFF (stop). Further, when the mode selection signal MDSEL indicates the selection of the low power mode, both the oscillation circuit 52 and the multiplication circuit 54 are turned off (stopped). When the mode selection signal MDSEL indicates the selection of the high-precision mode, the oscillation circuit 52 is turned off (stopped) and the multiplication circuit 54 is turned on (operated). The drive circuit 20 is turned on (operated) in any of the normal mode, the low power mode, and the high precision mode.

The clock output unit 50 outputs the clock signal CLK to the digital processing unit 40. Specifically, the clock output unit 50 is any of the clock signal CK1 output by the oscillation circuit 52, the clock signal CK2 output by the drive circuit 20, and the clock signal CK3 output by the multiplication circuit 54 based on the mode selection signal MDSEL. Select one of them and output it as a clock signal CLK. In the present embodiment, as shown in FIG. 7, when the mode selection signal MDSEL indicates the selection of the normal mode, the clock output unit 50 selects the clock signal CK1 and outputs it as the clock signal CLK. Further, when the mode selection signal MDSEL indicates the selection of the low power mode, the clock output unit 50 selects the clock signal CK2 and outputs it as the clock signal CLK. Further, when the mode selection signal MDSEL indicates the selection of the high-precision mode, the clock output unit 50 selects the clock signal CK3 and outputs it as the clock signal CLK.

As described above, in the present embodiment, in the normal mode (an example of the "second mode"), the oscillation circuit 52 operates, and the clock output unit 50 is a clock signal based on the output signal (clock signal CK1) of the oscillation circuit 52. Output CLK. Further, in the low power mode (an example of the "first mode"), the oscillation circuit 52 and the multiplication circuit 54 are stopped, and the clock output unit 50 outputs the clock signal CLK based on the output signal (clock signal CK2) of the drive circuit 20. Output. Further, in the high-precision mode (an example of the "third mode"), the oscillation circuit 52 is stopped and the multiplication circuit 54 is operated, and the clock output unit 50 clocks based on the output signal (clock signal CK3) of the multiplication circuit 54. Output the signal CLK.

The physical quantity sensor 1 (signal processing circuit 3) sets a normal mode, a low power mode, and a high precision mode based on a signal (mode selection data written to the register 61) input from the outside via the interface circuit 70. You may switch. Then, when the mode selection data held in the register 61 is changed, the clock output unit 50 switches the selection of the clock signal CK1, the clock signal CK2, and the clock signal CK3 so that glitches do not occur in the clock signal CLK. That is, in the present embodiment, the physical quantity sensor 1 (signal processing circuit 3) switches between a normal mode, a low power mode, and a high precision mode so that glitches do not occur in the clock signal CLK. This makes it possible to prevent malfunction of the digital processing unit 40 due to glitching of the clock signal CLK.

Further, when switching from the normal mode or the low power mode to the high precision mode, the clock output unit 50 receives a clock signal after the LOCK signal output by the multiplication circuit 54 becomes active (the frequency of the clock signal CK3 is stable). The clock signal CLK is output by switching from the CK1 or the clock signal CK2 to the clock signal CK3. This makes it possible to prevent malfunction of the digital processing unit 40 due to the unstable clock signal CLK.

The digital processing unit 40 includes an A / D (Analog to Digital) converter 42 (an example of an “analog / digital converter”) and a DSP (Digital Signal Processor) 44.

The A / D converter 42 operates in synchronization with the clock signal CLK output by the clock output unit 50, converts the output signal of the vibration type sensor 4 (detection circuit 30) into a digital signal (angle velocity data), and outputs the signal. .. The digital signal (angular velocity data) output from the A / D converter 42 is sequentially updated at a predetermined rate. The A / D converter 42 may be, for example, a delta-sigma type or a sequential comparison type A / D conversion circuit.

The DSP 44 operates in synchronization with the clock signal CLK output by the clock output unit 50, and performs digital processing including filter processing on the digital signal (angle velocity data) output from the A / D converter 42. The DSP44 is filtered by, for example, a first-order IIR (Infinite impulse response) filter as shown in FIG. In FIG. 8, X is input data to the IIR filter, and Y is output data from the IIR filter. The filter coefficients a ₁ , b ₀ , and b ₁ are stored in, for example, the storage unit 60 (nonvolatile memory 62).

Further, the DSP 44 may perform digital processing for correcting the offset of the zero point of the angular velocity data and the fluctuation of the angular velocity data due to the temperature. The value of the angular velocity data obtained by these digital processes represents the angular velocity detected by the physical quantity detecting element 2, and is sequentially updated at a predetermined rate. Further, the DSP 44 may perform digital processing for calculating the angular velocity data by time-integrating (adding) the angular velocity data that is sequentially updated.

In the normal mode, the clock signal CK1 output by the oscillation circuit 52 having a higher oscillation frequency than the drive circuit 20 is selected as the clock signal CLK, and the digital processing unit 40 (A / D converter 42 and DSP 44) processes at high speed. Since this is done, the power consumption of the physical quantity sensor 1 (signal processing circuit 3) is large. On the other hand, in the low power mode, the clock signal CK2 output by the drive circuit 20 is selected as the clock signal CLK, the digital processing unit 40 performs processing at a low speed, and the oscillation circuit 52 and the multiplication circuit 54 are stopped. Therefore, the power consumption of the physical quantity sensor 1 (signal processing circuit 3) is very small.

Here, since the frequency of the clock signal CLK is different between the normal mode and the low power mode, the sampling frequency in the filtering process of the DSP 44 is also different. Therefore, in the present embodiment, the digital processing unit 40 initializes the filter processing of the DSP 44 after switching between the normal mode and the low power mode. For example, when the DSP 44 performs filtering by the first-order IIR filter shown in FIG. 8, in order to shorten the transient response time of the filtering, the digital processing unit 40 switches to the normal mode or the low power mode after switching to the normal mode or the low power mode. The data held by the delay circuit Z ^-1 is initialized to the input data X. _{Further, the digital processing unit 40 initializes the filter coefficients a 1} , b ₀ , and b ₁ to desired values after switching to the normal mode or the low power mode. For example, in order to make the detection band of the angular velocity invariant between the normal mode and the low power mode, the digital processing unit 40 initializes the filter processing so that the cutoff frequency becomes constant between the normal mode and the low power mode. May be good. Specifically, when the DSP44 is filtered by the primary IIR filter shown in FIG. 8, if the sampling frequency is 10 kHz in the normal mode and the sampling frequency is 1 kHz in the low power mode, for example, the filter. coefficients _{a 1, b 0,} b 1 is, _a 1 = -0.93906 in normal _mode, b ₀ = b 1 = 0.03047 become, in the low power mode _{a 1 = -0.50953, b 0 =} b _{By initializing the filtering process so that 1} = 0.024524, the cutoff frequency can be made constant at 100 Hz. Even if the frequency of the clock signal CLK differs between the normal mode and the high-precision mode, the digital processing unit 40 initializes the filter processing of the DSP 44 so that the cutoff frequency becomes constant between the normal mode and the high-precision mode. You may.

FIG. 10 is a diagram showing an example of the waveform of each clock signal and the operation of the digital processing unit 40 when switching from the normal mode to the low power mode. Further, FIG. 11 is a diagram showing an example of the waveform of each clock signal and the operation of the digital processing unit 40 when switching from the low power mode to the normal mode. In both FIGS. 10 and 11, the operation mode is switched so that glitches do not occur in the clock signal CLK, and the filtering process of the DSP 44 is initialized immediately after the operation mode is switched. Further, in the low power mode, the clock signal CK1 and the clock signal CK3 are fixed at a constant voltage (low level).

In the present embodiment, the oscillation circuit 52 is an oscillation circuit realized in a small area such as a CR oscillator or a ring oscillator, and the frequency temperature characteristic of the clock signal CK1 output by the oscillation circuit 52 is affected by the temperature characteristic of the semiconductor element. receive. On the other hand, since the physical quantity detecting element 2 has, for example, a crystal vibration piece having high temperature stability, the clock signal CK2 output by the drive circuit 20 has extremely good frequency temperature characteristics as compared with the clock signal CK1. FIG. 9 is a diagram showing an example of the frequency temperature characteristics of the clock signal CK1 and the clock signal CK2. The solid line shows the frequency temperature characteristics of the clock signal CK1 and the broken line shows the frequency temperature characteristics of the clock signal CK2. In the example of FIG. 9, the frequency deviation of the clock signal CK1 is in the range of about ± 0.2% in the range of −35 ° C. to + 85 ° C. (operating temperature range), whereas the frequency deviation of the clock signal CK2 is ± 0. It is in the range of 0.01% or less.

Therefore, in the present embodiment, in the high-precision mode, the clock signal CK3 having a small frequency deviation obtained by multiplying the clock signal CK2 is selected as the clock signal CLK, and the digital processing unit 40 digitally processes the clock signal CK2 with higher precision than in the normal mode. It is possible to do. For example, when the digital processing unit 40 (DSP44) time-integrates (adds) the angular velocity data to calculate the angular data, the integration error can be reduced by setting the operation mode to the high-precision mode. Highly accurate angle data can be obtained. Further, the frequency of the clock signal CK1 and the frequency of the clock signal CK3 may be the same so that the digital processing rate does not change between the normal mode and the high precision mode. For example, the output signal of a CR oscillator or the like that the oscillation circuit 52 oscillates at a very high frequency may be divided by an integer with a frequency dividing circuit to output a clock signal CK1 having the same frequency as the clock signal CK3. In this high-precision mode, the oscillation circuit 52 that oscillates at a very high frequency is stopped, so that the power consumption of the physical quantity sensor 1 is reduced.

FIG. 12 is a diagram showing an example of the waveform of each clock signal and the operation of the digital processing unit 40 when switching from the normal mode to the high precision mode. In FIG. 12, the clock signal CK3 is output as the clock signal CLK after the multiplication circuit 54 starts operation and the LOCK signal becomes active (high level). Further, in the high precision mode, the clock signal CK1 is fixed at a constant voltage (low level). In the example of FIG. 12, the frequency of the clock signal CK1 and the frequency of the clock signal CK3 are the same, and the filter coefficient is not changed in the normal mode and the high precision mode, and the filter processing is not initialized. , The filtering process may be initialized immediately after switching to the high-precision mode.

As described above, in the physical quantity sensor 1 (signal processing circuit 3) of the first embodiment, the clock signal CLK output from the clock output unit 50 to the digital processing unit 40 is output by the oscillation circuit 52 in the normal mode. The clock signal CK1 is a clock signal CK2 output by the drive circuit 20 having an oscillation frequency lower than that of the oscillation circuit 52 in the low power mode. Therefore, in the low power mode, the digital processing unit 40 can process the output signal of the vibration type sensor 4 with a lower current consumption than in the normal mode per unit time. Therefore, according to the physical quantity sensor 1 (signal processing circuit 3) of the first embodiment, the current consumption can be reduced in the low power mode as compared with the normal mode for sensing.

Further, in the physical quantity sensor 1 (signal processing circuit 3) of the first embodiment, in the normal mode, the clock signal CLK having a frequency higher than that in the low power mode is output from the clock output unit 50 to the digital processing unit 40. The processing unit 40 can process the output signal of the vibration type sensor 4 at a higher rate than in the low power mode. Therefore, according to the physical quantity sensor 1 (signal processing circuit 3) of the first embodiment, it is possible to perform sensing in the normal mode with higher resolution than in the low power mode.

Further, in the physical quantity sensor 1 (signal processing circuit 3) of the first embodiment, in the high precision mode, the clock output unit 50 has a higher frequency than the low power mode and a smaller frequency deviation than the normal mode. Since the signal CK3 is output to the digital processing unit 40, the digital processing unit 40 processes the output signal of the vibration type sensor 4 at a higher rate than in the low power mode and with higher accuracy than in the normal mode. Can be done. Therefore, according to the physical quantity sensor 1 (signal processing circuit 3) of the first embodiment, it is possible to perform sensing in the high accuracy mode with higher resolution than in the low power mode and with higher accuracy than in the normal mode.

Further, in the physical quantity sensor 1 (signal processing circuit 3) of the first embodiment, one of a normal mode, a low power mode, and a high precision mode can be selected based on a signal from the outside. That is, according to the physical quantity sensor 1 (signal processing circuit 3) of the first embodiment, it is possible to freely switch between low current consumption sensing, high resolution sensing, and high precision sensing by an external device during operation. ..

Further, in the physical quantity sensor 1 (signal processing circuit 3) of the first embodiment, glitches do not occur in the clock signal CLK when the operation mode is switched, so that the malfunction of the digital processing unit 40 can be prevented.

Further, in the physical quantity sensor 1 (signal processing circuit 3) of the first embodiment, the data to be filtered by the digital processing unit 40 is initialized immediately after the operation mode is switched, so that the transient response time of the filtering process is timed. Can be shortened, and the filter characteristics can be optimized because the filter coefficient is initialized. For example, by changing the filter coefficient between the low power mode, the normal mode, and the high precision mode, the cutoff frequency of the filter processing by the digital processing unit 40 can be kept constant regardless of the operation mode. As a result, the sensing detection band can be kept constant regardless of the operation mode. Further, in the low power mode, when it is sufficient to sense only the low frequency angular velocity signal, the cutoff frequency of the filtering in the low power mode is set to be lower than the cutoff frequency in the normal mode and the high precision mode. The S / N of sensing in the power mode can be improved.

1-2. Second Embodiment Hereinafter, the physical quantity sensor 1 of the second embodiment will be mainly described with contents different from those of the first embodiment, and the description overlapping with the first embodiment will be omitted. FIG. 13 is a functional block diagram of the physical quantity sensor of the second embodiment. In FIG. 13, the same reference numerals are given to the same configurations as those in the first embodiment. In the physical quantity sensor 1 of the second embodiment, the signal processing circuit 3 is configured to include the interface circuit 80 in addition to the configuration as in the first embodiment.

The interface circuit 80 is electrically connected to the MSCK terminal and the MSDA terminal, and is a circuit for communicating with a plurality of external devices via these terminals. In communication via the interface circuit 80, the physical quantity sensor 1 (signal processing circuit 3) functions as a master, and a plurality of external devices function as slaves. Then, the physical quantity sensor 1 (signal processing circuit 3) writes data to a predetermined address of a storage unit (register) of each of the plurality of external devices via the interface circuit 80, or the plurality of external devices each write data. Data can be read from a predetermined address of the storage unit (register) having the data. Interface circuit 80, for example, functions as I 2 ^C interface circuit, outputs a clock signal through the MSCK terminal, the data signal is input and output via the MSDA terminal.

Address and data information used in communication with a plurality of external devices via the interface circuit 80 is set in the register 61.

In the present embodiment, the digital processing unit 40 includes a posture calculation unit 46 in addition to the A / D converter 42 and the DSP 44.

The attitude calculation unit 46 operates in synchronization with the clock signal CLK output by the clock output unit 50, and executes the attitude calculation based on the three-axis angular velocity data. Specifically, the attitude calculation unit 46 sequentially acquires the first angular velocity data representing the _{angular velocity ω 1 of the first axis from the DSP 44 in a predetermined period Δt.} Further, the attitude calculation unit 46 sequentially acquires from a plurality of external devices via the interface circuit 80 at a period Δt and stores it in the storage unit 60 (register 61), and represents the second angular _{velocity ω 2 of the second axis.} The data and the third angular velocity data representing the _{angular velocity ω 3 of the third axis are sequentially acquired.} The first axis, the second axis, and the third axis are, for example, axes that are orthogonal to each other. Then, the attitude calculation unit 46 performs the attitude calculation using the first angular velocity data (angular velocity ω ₁ ), the second angular velocity data (angular velocity ω ₂ ), and the third angular velocity data (angular velocity ω ₃ ) sequentially acquired in the period Δt. ..

In the present embodiment, the attitude calculation unit 46 is stored in the storage unit 60 (nonvolatile memory 62), and the x-axis, y-axis, and z, which are predefined as the first axis, the second axis, and the third axis. Using the information on the correspondence with the axes, for example, the first angular velocity data (angular velocity ω ₁ ) is recognized as the x-axis angular velocity data (angular velocity ω _x around the x-axis), and the second angular velocity data (angular velocity ω ₂ ). Is recognized as y-axis angular velocity data (angular velocity ω _y around the y-axis), and the third angular velocity data (angular velocity ω ₃ ) is recognized as z-axis angular velocity data (angular velocity ω _z around the z-axis). Then, the attitude calculation unit 46 is a quaternion based on _{the angular velocity ω x} (= ω _{1 ) around the x-axis, the angular velocity ω y} (= ω ₂ ) around the y-axis, _{and the angular velocity ω z} (= ω ₃ ) around the z-axis. Posture calculation can be performed using. For example, the attitude calculation unit 46 updates the quaternion q according to the equation (1) every time it acquires _{the angular velocities ω x} , ω _y , ω _{z for three axes, and normalizes the updated quaternion q according to the equation (2).} By doing so, the posture calculation is performed.

FIG. 14 is a diagram showing a configuration example of a posture calculation unit 46 that performs a posture calculation using a quaternion. As shown in FIG. 14, the posture calculation unit 46 includes a conversion unit 211, a matrix calculation unit 212, a multiplier 213, an adder 214, and a normalization unit 215.

The conversion unit 211 is based on the information on the correspondence between the first, second and third axes and the x-axis, y-axis and z-axis stored in the storage unit 60 (nonvolatile memory 62). The three-axis angular velocity data (angular velocity ω ₁ , ω ₂ , ω _{3 ) is converted into an angular velocity ω x} around the x-axis, an angular _{velocity ω y} around the y-axis, and an angular velocity ω _z around the z-axis and output.

In synchronization with the clock signal CLK, the matrix calculation unit 212 has an angular velocity ω _x around the x-axis, an angular velocity around the y-axis, and an angular velocity ω _z around the z-axis (both units are LSB) and the latest quaternion q (each element). The unit of q _w , q _x , q _y , and q _z is radian), and the part of the matrix product in the first term on the right side of equation (1) is calculated and output.

The multiplier 213 calculates and outputs the product of the output value of the matrix calculation unit 212 and the coefficient value COEF. The output value of the multiplier 213 corresponds to the calculated value of the first term on the right side of the equation (1). The coefficient value COEF is stored in the storage unit 60 (nonvolatile memory 62) and is a constant value calculated by the equation (3).

In the formula (3), the GS is the detection circuit 30 (GS is the detection sensitivity of the physical quantity detection element 2 (unit: ° / s / LSB)). Further, FRQ is a frequency (unit: Hz) of the clock signal CLK.

The adder 214 calculates and outputs the sum of the output value of the multiplier 213 and the latest quaternion q. The output value of the adder 214 corresponds to the calculated value of the equation (1).

The normalization unit 215 synchronizes with the clock signal CLK, normalizes the output value of the adder 214 so that its magnitude becomes 1, and outputs it. The output value of the normalization unit 215 corresponds to the calculated value of the equation (2) and becomes the latest quaternion q. Then, the result of the posture calculation (quaternion q) by the posture calculation unit 46 is stored in the storage unit 60 (register 61), and is output via the interface circuit 70 in response to a request from the external device.

FIG. 15 is a diagram showing a configuration example of a posture calculation device 6 using the physical quantity sensor 1 of the second embodiment. The posture calculation device 6 shown in FIG. 15 includes three physical quantity sensors 1 (1-1, 1-2, 1-3). Each physical quantity sensor 1-k (k = 1 to 3) includes a physical quantity detection element 2-k and a signal processing circuit 3-k.

The MSCK terminal of the signal processing circuit 3-1 provided by the physical quantity sensor 1-1, the SCLK terminal of the signal processing circuit 3-2 provided by the physical quantity sensor 1-2, and the signal provided by the physical quantity sensor 1-3. The SCLK terminal of the processing circuit 3-3 is electrically connected. Further, the MSDA terminal of the signal processing circuit 3-1 provided by the physical quantity sensor 1-1, the MOSI terminal of the signal processing circuit 3-2 provided by the physical quantity sensor 1-2, and the physical quantity sensor 1-3 are provided. The MOSI terminal of the signal processing circuit 3-3 is electrically connected. Then, the physical quantity sensor 1-1 (posture calculation unit 46 (see FIG. 13) of the signal processing circuit 3-1) performs the posture calculation.

The physical quantity sensor 1-1 (signal processing circuit 3-1) communicates with the physical quantity sensors 1-2 and 1-3 via the interface circuit 80 (see FIG. 13), respectively. The physical quantity sensors 1-2 and 1-3 communicate with the physical quantity sensor 1-1 via the interface circuit 70 (see FIG. 13). In the signal processing circuit 3-2 and 3-3, which is pulled up XCS terminal to the power supply, the interface circuit 70 of the signal processing circuit 3-2 and 3-3 function as ^{I 2} C interface circuit. The master physical quantity sensor 1-1 (signal processing circuit 3-1) writes data to the slave physical quantity sensors 1-2, 1-3 (signal processing circuit 3-2, 3-3). Read the data. Therefore, the physical quantity sensor 1-1 (signal processing circuit 3-1) _{reads and acquires the second angular velocity data (angular velocity ω 2} ) from the physical quantity sensor 1-2 (signal processing circuit 3-2), and obtains the physical quantity sensor 1-. The third angular velocity data (angular velocity ω ₃ ) can be read out and acquired from 3 (signal processing circuit 3-3).

Then, the physical quantity sensor 1-1 (signal processing circuit 3-1) receives the first angular velocity data (angular velocity ω ₁ ) detected by itself, and the physical quantity sensor 1-2 (signal processing circuit 3-2) to the second angular velocity data (). The attitude calculation is performed based on _{the third angular velocity data (angular velocity ω 3} ) from the angular velocity ω ₂ ) and the physical quantity sensor 1-3 (signal processing circuit 3-3).

Further, the physical quantity sensor 1-1 (signal processing circuit 3-1) communicates with the control device 5 which is a host via the interface circuit 70 (see FIG. 13). The interface circuit 70 of the signal processing circuit 3-1 functions as an SPI interface circuit, and the master control device 5 writes data to the slave physical quantity sensor 1-1 (signal processing circuit 3-1). And read data, or send a command. Therefore, the control device 5 can read and acquire the result of the posture calculation (quaternion q) from the posture calculation device 6.

The posture calculation device 6 configured in this way is attached to an object for posture calculation, for example, in a packaged state. Then, the attitude calculation unit 46 of the physical quantity sensor 1-1 (signal processing circuit 3-1) calculates the quaternion q according to the equations (1) and (2), where one cycle of the clock signal CLK is Δt. Then, from the equations (1) and (2), the calculation accuracy of the quaternion q is determined by the accuracy of Δt, that is, the frequency accuracy of the clock signal CLK output by the clock output unit 50. As described above, for example, the frequency deviation of the clock signal CK1 is in the range of about ± 0.2%, while the frequency deviation of the clock signal CK2 is in the range of ± 0.01% or less. Therefore, in the physical quantity sensor 1-1 (signal processing circuit 3-1), in order to improve the calculation accuracy by the attitude calculation unit 46, the clock signal CK3 having a small frequency deviation obtained by multiplying the clock signal CK2 is selected as the clock signal CLK. It is desirable to set to the high-precision mode. On the other hand, the physical quantity sensor 1-2 (signal processing circuit 3-2) _{need only output the second angular velocity data (angular velocity ω 2} ), and the attitude calculation unit 46 does not have to operate (calculation based on Δt needs to be performed). There is no), so it may be set to normal mode. Similarly, the physical quantity sensor 1-3 (signal processing circuit 3-3) may _{output the third angular velocity data (angular velocity ω 3} ), and the attitude calculation unit 46 does not have to operate (calculation based on Δt is performed). It is not necessary), so it may be set to normal mode. In the attitude calculation device 6, power consumption is consumed by setting each operation mode of the physical quantity sensor 1-1, 1-2, 1-3 (signal processing circuit 3-1, 3-2, 3-3) in this way. It is possible to perform posture calculation with high accuracy while suppressing the increase of.

2. 2. Electronic device FIG. 16 is a functional block diagram showing an example of the configuration of the electronic device of the present embodiment. As shown in FIG. 16, the electronic device 300 of the present embodiment includes a physical quantity sensor 310, a control device (MCU) 320, an operation unit 330, a ROM (Read Only Memory) 340, and a RAM (Random Access).
Memory) 350, communication unit 360, and display unit 370 are included. The electronic device of the present embodiment may be configured such that a part of the component (each part) of FIG. 16 is omitted or changed, or another component is added.

The physical quantity sensor 310 detects the physical quantity and outputs the detection result to the control device (MCU) 320. As the physical quantity sensor 310, for example, the physical quantity sensor 1 of the present embodiment described above can be applied.

The control device (MCU) 320 transmits a communication signal to the physical quantity sensor 310 according to a program stored in the ROM 340 or the like, and performs various calculation processes and control processes using the output signal of the physical quantity sensor 310. In addition, the control device (MCU) 320 performs various processes according to the operation signal from the operation unit 330, processes for controlling the communication unit 360 for data communication with the external device, and displays various information on the display unit 370. Performs processing such as transmitting a display signal for making the display signal.

The operation unit 330 is an input device composed of operation keys, button switches, and the like, and outputs an operation signal corresponding to the operation by the user to the control device (MCU) 320.

The ROM 340 stores programs, data, and the like for the control device (MCU) 320 to perform various calculation processes and control processes.

The RAM 350 is used as a work area of the control device (MCU) 320, and includes programs and data read from the ROM 340, data input from the operation unit 330, calculation results executed by the control device (MCU) 320 according to various programs, and the like. Is temporarily memorized.

The communication unit 360 performs various controls for establishing data communication between the control device (MCU) 320 and the external device.

The display unit 370 is a display device composed of an LCD (Liquid Crystal Display) or the like, and displays various information based on a display signal input from the CPU 320. The display unit 370 may be provided with a touch panel that functions as an operation unit 330.

By applying, for example, the physical quantity sensor 1 of the present embodiment described above as the physical quantity sensor 310, for example, a highly reliable electronic device can be realized.

Various electronic devices can be considered as such electronic devices 300, for example, personal computers (for example, mobile personal computers, laptop personal computers, tablet personal computers), mobile terminals such as smartphones and mobile phones, and the like. Digital cameras, inkjet ejection devices (for example, inkjet printers), storage area network devices such as routers and switches, local area network devices, mobile terminal base station devices, televisions, video cameras, video recorders, car navigation devices, real-time Clock devices, pagers, electronic notebooks (including those with communication functions), electronic dictionaries, calculators, electronic game devices, game controllers, word processors, workstations, videophones, security TV monitors, electronic binoculars, POS terminals, medical devices ( For example, electronic thermometer, blood pressure monitor, blood glucose meter, electrocardiogram measuring device, ultrasonic diagnostic device, electronic endoscope), fish finder, various measuring devices, instruments (for example, instruments for vehicles, aircraft, ships), flight simulator. , Head mount display, motion trace, motion tracking, motion controller, PDR (pedestrian position and orientation measurement) and the like.

FIG. 17 is a perspective view schematically showing a digital camera 1300 which is an example of the electronic device 300 of the present embodiment. Note that FIG. 17 also briefly shows the connection with an external device. Here, while a normal camera sensitizes a silver halide photographic film by the light image of the subject, the digital camera 1300 performs photoelectric conversion of the light image of the subject by an image sensor such as a CCD (Charge Coupled Device) and captures the image. Generate a signal (image signal).

A display unit 1310 is provided on the back surface of the case (body) 1302 of the digital camera 1300, and is configured to display based on an image pickup signal by a CCD. The display unit 1310 is a finder that displays a subject as an electronic image. Functions as. Further, on the front side (back side in the drawing) of the case 1302, a light receiving unit 1304 including an optical lens (imaging optical system), a CCD, and the like is provided. When the photographer confirms the subject image displayed on the display unit 1310 and presses the shutter button 1306, the image pickup signal of the CCD at that time is transferred and stored in the memory 1308. Further, in the digital camera 1300, a video signal output terminal 1312 and an input / output terminal 1314 for data communication are provided on the side surface of the case 1302. A television monitor 1430 is connected to the video signal output terminal 1312, and a personal computer 1440 is connected to the data communication input / output terminal 1314, respectively, as needed. Further, the imaging signal stored in the memory 1308 is output to the television monitor 1430 or the personal computer 1440 by a predetermined operation. The digital camera 1300 has a physical quantity sensor 310, and uses the output signal of the physical quantity sensor 310 to perform processing such as camera shake correction.

3. 3. The moving body FIG. 18 is a view (top view) showing an example of the moving body of the present embodiment. The moving body 400 shown in FIG. 18 includes a physical quantity sensor 410, controllers 440, 450, 460, a battery 470, and a navigation device 480. The moving body of the present embodiment may be configured by omitting a part of the constituent elements (each part) of FIG. 18 or adding other constituent elements.

The physical quantity sensor 410, the controllers 440, 450, 460, and the navigation device 480 operate on the power supply voltage supplied from the battery 470.

The physical quantity sensor 410 detects the physical quantity and outputs the detection result to the controllers 440, 450, 460.

The controllers 440, 450, and 460 are control devices that perform various controls such as an attitude control system, a rollover prevention system, and a brake system, respectively, using the output signals of the physical quantity sensor 410.

The navigation device 480 displays various information such as the position and time of the mobile body 400 on the display based on the output information of the built-in GPS receiver (not shown). Further, the navigation device 480 identifies the position and orientation of the moving body 400 based on the output signal of the physical quantity sensor 410 even when the GPS radio wave does not reach, and continues to display necessary information.

For example, by applying the physical quantity sensor 1 of each of the above-described embodiments as the physical quantity sensor 410, for example, a highly reliable moving body can be realized.

Various moving bodies can be considered as such moving bodies 400, and examples thereof include automobiles (including electric vehicles), aircraft such as jet aircraft and helicopters, ships, rockets, and artificial satellites.

4. Modifications The present invention is not limited to the present embodiment, and various modifications can be carried out within the scope of the gist of the present invention.

For example, the physical quantity sensor 1 (signal processing circuit 3) of each of the above embodiments has three operation modes of a normal mode, a low power mode, and a high precision mode, but has other operation modes. May be good. Alternatively, the physical quantity sensor 1 (signal processing circuit 3) of each of the above embodiments does not have to have a high-precision mode as an operation mode.

Further, for example, in the physical quantity sensor 1 (signal processing circuit 3) of each of the above embodiments, the A / D converter 42 and the DSP 44 are operated by a common clock signal CLK, but are operated by different clock signals. You may. For example, the DSP 44 may be operated by the clock signal CLK output by the clock output unit 50, and the A / D converter 42 may be operated by the divided clock signal of the clock signal CLK.

Further, for example, in the above-described embodiment, a physical quantity sensor (angle velocity sensor) including a physical quantity detection element for detecting the angular velocity, and an electronic device and a moving body provided with the physical quantity sensor (angular velocity sensor) have been described as examples. The present invention can also be applied to a physical quantity sensor including a physical quantity detecting element that detects various physical quantities, and an electronic device and a moving body provided with the physical quantity sensor. The physical quantity detected by the physical quantity detecting element is not limited to the angular velocity, and may be angular acceleration, acceleration, geomagnetism, inclination, or the like. Therefore, the vibration type sensor is not limited to the vibration type angular velocity sensor, and may be, for example, a vibration type pressure sensor, a vibration type tilt sensor, or the like. Further, the vibrating piece of the physical quantity detecting element does not have to be a double T type, for example, a tuning fork type or a comb tooth type, or a sound piece type having a shape such as a triangular prism, a square prism, or a columnar prism. May be good. As a material for the vibrating piece of the physical quantity detecting element, _{instead of crystal (SiO 2} ), for example, _{a piezoelectric single crystal such as lithium tantalate (LiTaO 3} ) or lithium niobate (LiNbO ₃ ) or lead zirconate titanate is used. Piezoelectric materials such as piezoelectric ceramics such as (PZT) may be used, or silicon semiconductors may be used. Further, for example, the structure may be such that a piezoelectric thin film such as zinc oxide (ZnO) or aluminum nitride (AlN) sandwiched between driving electrodes is arranged on a part of the surface of the silicon semiconductor. Further, the physical quantity detecting element is not limited to the piezoelectric type element, and may be a vibration type element such as an electrokinetic type, a capacitance type, an eddy current type, an optical type, or a strain gauge type. Alternatively, the method of the physical quantity detecting element is not limited to the vibration type, and may be, for example, an optical type, a rotary type, or a fluid type.

The above-described embodiments and modifications are merely examples, and the present invention is not limited thereto. For example, it is also possible to appropriately combine each embodiment and each modification.

The present invention includes a configuration substantially the same as the configuration described in the embodiment (for example, a configuration having the same function, method and result, or a configuration having the same purpose and effect). The present invention also includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same effects as the configuration described in the embodiment or a configuration that can achieve the same object. The present invention also includes a configuration in which a known technique is added to the configuration described in the embodiment.

1,1-1,1-2,1-3 ... Physical quantity sensor, 2,2-1,2,2-3 ... Physical quantity detection element, 3,3-1,3-2,3-3 ... Signal Processing circuit, 4 ... Vibration type sensor, 5 ... Control device, 6 ... Attitude calculation device, 10 ... Reference voltage circuit, 20 ... Drive circuit, 21 ... I / V conversion circuit, 22 ... Low pass filter, 23 ... High pass filter, 24 ... comparator, 25 ...
Full-wave rectifier circuit, 26 ... integrator, 27 ... comparator, 28 ... comparator, 30 ... detection circuit, 31 ... QV amplifier, 32 ... differential amplifier, 33 ... variable gain amplifier, 34 ... synchronous detection circuit, 40 ... Digital processing unit, 42 ... A / D conversion circuit, 44 ... DSP, 46 ... attitude calculation unit, 50 ... clock output unit, 52 ... oscillation circuit, 54 ... multiplication circuit, 60 ... storage unit, 61 ... register, 62 ... non-volatile Sex memory, 70 ... interface circuit, 80 ... interface circuit, 101a, 101b ... drive vibrating arm, 102 ... detection vibrating arm, 103 ... weight part, 104a, 104b ... drive base, 105a, 105b ... connecting arm, 106 ... weight Unit, 107 ... Detection base, 112, 113 ... Drive electrode, 114, 115 ... Detection electrode, 116 ... Common electrode, 211 ... Conversion unit, 212 ... Matrix calculation unit, 213 ... Multiplier, 214 ... Adder, 215 ... Normalization unit, 300 ... electronic device, 310 ... physical quantity sensor, 320 ... control device (MCU), 330 ... operation unit, 340 ... ROM, 350 ... RAM, 360 ... communication unit, 370 ... display unit, 400 ... mobile body, 410 ... Physical quantity sensor, 440, 450, 460 ... Controller, 470 ... Battery, 480 ... Navigation device, 1300 ... Digital camera, 1302 ... Case, 1304 ... Light receiving unit, 1306 ... Shutter button, 1308 ... Memory, 1310 ... Display unit, 1312 ... Video signal output terminal, 1314 ... Input / output terminal, 1430 ... TV monitor, 1440 ... Personal computer

Claims (7)

A vibration type sensor including the first oscillation circuit and
The second oscillator circuit, which has a higher oscillation frequency than the first oscillator circuit,
A multiplication circuit that multiplies the output signal of the first oscillation circuit,
A digital processing unit that includes an analog / digital converter that converts the output signal of the vibration type sensor into a digital signal and digitally processes the digital signal based on the clock signal.
The digital processing unit is provided with a clock output unit that outputs the clock signal.
The output signal of the first oscillation circuit has a smaller frequency deviation than the output signal of the second oscillation circuit.
A first mode in which said second oscillator circuit is stopped, the clock output unit outputs said clock signal based on the output signal of the first oscillator circuit,
A second mode for outputting said clock signal on the basis of the clock output unit to the output signal of the second oscillator circuit,
A third mode in which the clock output unit outputs the clock signal based on the output signal of the multiplication circuit.
Has a physical quantity sensor. The physical quantity sensor according to claim 1, which switches between the first mode and the second mode based on a signal input from the outside. The physical quantity sensor according to claim 2, which switches between the first mode and the second mode so that glitches do not occur in the clock signal. The digital processing includes filtering processing.
The digital processing unit
The physical quantity sensor according to claim 2 or 3, wherein the filtering process is initialized after the first mode and the second mode are switched. The digital processing unit
The physical quantity sensor according to claim 4, wherein the filtering process is initialized so that the cutoff frequency becomes constant in the first mode and the second mode. An electronic device comprising the physical quantity sensor according to any one of claims 1 to 5. A mobile body comprising the physical quantity sensor according to any one of claims 1 to 5.

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