WO2015064349A1

WO2015064349A1 - Physical-quantity detection device

Info

Publication number: WO2015064349A1
Application number: PCT/JP2014/077281
Authority: WO
Inventors: 都留　康隆; 雅秀林; 和典太田; 貴大石田; 一朗大坂
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2013-10-29
Filing date: 2014-10-14
Publication date: 2015-05-07
Also published as: JPWO2015064349A1

Abstract

This invention provides a physical-quantity detection device, such as an angular-velocity sensor or an acceleration sensor, that operates in a power-saving mode in which power consumption is reduced, wherein with power consumption in said power-saving mode reduced, the amount of time it takes for the physical-quantity detection device to return to normal operation is reduced and the desired physical quantity can be detected in a sophisticated manner. When a communication unit (125) receives a transition-instruction signal that constitutes an instruction to transition to the power-saving mode, a power-supply control unit (141) continues supplying a voltage to a drive unit (111), a vibration-direction displacement-amount detection unit (110), a drive-control-value computation unit (122), and the communication unit (125) but stops supplying said voltage to other circuit units.

Description

Physical quantity detection device

The present invention relates to a physical quantity detection device, for example, a physical quantity detection device that detects physical quantities such as angular velocity and acceleration.

Conventionally, there is known a travel control system that detects a rotation angle of a vehicle body in real time by an angular velocity sensor, which is a kind of inertial sensor, and controls a travel state of the vehicle body (for example, skidding or rollover). Also known is a system that detects the tilt of a mobile phone by an acceleration sensor, which is a kind of inertial sensor, and changes the direction of the output screen. Such an inertial sensor, particularly an inertial sensor created using MEMS (Micro Electro Mechanical System) technology, is composed of, for example, a fixed electrode, a movable electrode, an inertial body (vibrator), and the like, and an inertial body is obtained by physical force. By detecting the amount of movement from the change in capacitance between the fixed electrode and the movable electrode, the physical quantity acting on the inertial body is calculated.

By the way, the electrical equipment mounted on the traveling control system of a vehicle such as an automobile needs to cope with a decrease in battery voltage, that is, a decrease in supply voltage caused by engine stop when parking or stopping. Therefore, for example, in the automobile field, a technology is adopted in which the electrical equipment is shifted to a power saving mode with low power consumption when the engine is stopped by an engine control unit (ECU) that controls the operating state of the engine. Japanese Patent Application Laid-Open No. 2004-133867 discloses a technique for vibrating an inertial sensor in a power saving mode.

In order to obtain a large drive amplitude with low energy consumption, an inertial sensor (angular velocity sensor) disclosed in Patent Document 1 always generates a drive signal that matches the natural frequency of the sensor and causes the angular velocity sensor to display the natural vibration. It is driven by numbers.

JP 2009-145321 A

By the way, for example, an inertial sensor such as an angular velocity sensor needs to detect a physical quantity (for example, an angular velocity) in a state where a vibrator built in the inertial sensor stably vibrates at a predetermined frequency and amplitude. It is known that once the vibrator is stopped, it takes a predetermined time to return from the stopped state to a stable vibration state.

In the power saving mode described above, in order to further reduce power consumption, the voltage (supply voltage) supplied from the outside to the electrical equipment is temporarily reduced to a predetermined value or stopped (momentary interruption). However, if voltage supply to an inertial sensor such as an angular velocity sensor is stopped, it takes time until the inertial sensor operates normally, and a desired physical quantity cannot be accurately detected. Can occur.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a physical quantity detection device such as an angular velocity sensor or an acceleration sensor that operates in a power saving mode with reduced power consumption in a power saving mode. It is an object of the present invention to provide a physical quantity detection device capable of precisely detecting a desired physical quantity by reducing the recovery time until the physical quantity detection apparatus normally operates while suppressing power consumption.

In order to solve the above-described problem, a physical quantity detection device according to the present invention is a physical quantity detection device that detects a physical quantity using a sensor element having a vibrator, and the physical quantity detection device shifts to a power saving mode. Alternatively, the power control unit includes a plurality of circuit units including a communication unit that receives a switching signal related to release, and a power supply control unit that controls voltage supply to the plurality of circuit units. When a transition instruction signal to power mode is received, voltage supply to the circuit units required for maintaining resonance vibration of the sensor element among the plurality of circuit units is continued and voltage supply to other circuit units is performed. It is characterized by stopping.

According to the physical quantity detection device of the present invention, among the plurality of circuit units constituting the physical quantity detection device, even when the voltage supply from the external power supply temporarily decreases in the power saving mode in which power consumption is suppressed, for example. Only the voltage supply to the circuit part related to the resonance vibration of the sensor element is continued, the operation of the sensor element is maintained, and the voltage supply to the other circuit parts is stopped, thereby reducing the power consumption in the power saving mode. While suppressing, the recovery time until the physical quantity detection device operates normally can be shortened, and a desired physical quantity can be precisely detected.

Issues, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

The system block diagram which shows the internal structure of 1st Embodiment of the physical quantity detection apparatus which concerns on this invention. FIG. 2 is a flowchart for explaining a processing flow when a digital signal processing unit DSP-A shown in FIG. 1 shifts to a power saving mode. FIG. 2 is a flowchart for explaining a processing flow when a power saving mode is canceled by the digital signal processor DSP-A shown in FIG. 1. The system block diagram which shows the internal structure of 2nd Embodiment of the physical quantity detection apparatus which concerns on this invention.

Hereinafter, an embodiment of a physical quantity detection device according to the present invention will be described with reference to the drawings. In the following description, an embodiment in which an angular velocity sensor is mainly used as the physical quantity detection device will be described, but it is needless to say that the present invention can be applied to, for example, an acceleration sensor.

<First Embodiment>
FIG. 1 shows an internal configuration of a first embodiment of an angular velocity sensor as a physical quantity detection device according to the present invention.

The illustrated angular velocity sensor 100 mainly includes an angular velocity sensor element (sensor element) 101, a capacitance detection unit (vibration direction displacement detection unit) 110, a drive signal generation unit (drive unit) 111, and a capacitance detection unit (Coriolis force displacement). (Quantity detection unit) 112, digital signal processing unit DSP-A (drive control value calculation unit) 122, digital signal processing unit DSP-B (physical quantity calculation unit) 123, communication unit 125, and power supply control unit 141 And a block (circuit unit).

The angular velocity sensor element 101 includes a vibrator 102,

fixed electrodes

108 and 109,

electrodes

104 and 105, and

fixed electrodes

106 and 107.

The vibrator 102 of the angular velocity sensor element 101 has a predetermined mass and vibrates in a predetermined vibration axis direction at a predetermined vibration frequency. The

fixed electrodes

108 and 109 apply an electrostatic force to adjust the vibration amplitude and vibration frequency in the vibration direction of the vibrator 102. The

electrodes

104 and 105 detect the vibration amplitude and vibration frequency of the vibrator 102 by a change in capacitance. The

fixed electrodes

106 and 107 detect a displacement generated in the vibrator 102 in a direction perpendicular to the vibration axis by a Coriolis force generated when an angular velocity is applied, based on a change in capacitance.

The capacitance detection unit 110 detects the difference between the electrostatic capacitance between the angular velocity sensor element 101 and the fixed electrode 104 and the electrostatic capacitance between the angular velocity sensor element 101 and the fixed electrode 105, so that the vibration direction acting on the angular velocity sensor 101 is detected. , And the detection result is stored in a RAM (Read Only Memory) 121 via the bus line 120.

The digital signal processing unit DSP-A 122 reads the displacement amount in the vibration direction of the vibrator 102 obtained by the capacitance detection unit 110 from the RAM 121, and the vibration in the driving direction of the vibrator 102 becomes the mechanical resonance vibration of the angular velocity sensor element 101. The frequency control value and the amplitude control value (drive control value) for the displacement amount are calculated so as to approach each other, and the calculation result is output to the drive signal generation unit 111 via the bus line 120.

The drive signal generator 111 generates an AC drive signal that adjusts the frequency and amplitude according to the frequency control value and the amplitude control value output from the digital signal processor DSP-A 122, and the fixed electrode 108 based on the drive signal. And 109 are controlled to vibrate the angular velocity sensor element 101 at a predetermined frequency and amplitude.

Such control by the capacitance detection unit 110, the digital signal processing unit DSP-A 122, and the drive signal generation unit 111 is feedback control, and the angular velocity sensor element 101 is made to reach and maintain its resonance vibration state.

Further, the capacitance detection unit 112 detects the difference between the capacitance between the vibrator 102 and the fixed electrode 106 and the capacitance between the vibrator 102 and the fixed electrode 107, so that the Coriolis force acting on the vibrator 102 is detected. The amount of displacement is detected, and the detection result is stored in the RAM 121 via the bus line 120.

The digital signal processing unit DSP-B 123 reads the displacement amount of the vibrator 102 obtained by the capacitance detection unit 112 from the RAM 121, performs synchronous detection at the resonance frequency in the above-described resonance vibration state, and detects an amplitude value for the displacement amount. The detection result (amplitude value) is stored in the RAM 121. Thereafter, the digital signal processor DSP-B 123 performs a temperature correction operation on the amplitude value stored in the RAM 121 using a detection value by the temperature sensor 113 and a correction coefficient stored in advance in a ROM (Random Access Memory) 124. The offset depending on the temperature included in the detection result (amplitude value) is removed. Further, the digital signal processing unit DSP-B 123 executes low-pass filter processing to remove high frequency noise components, and then stores the amplitude value in the RAM 121 as an angular velocity detection value.

The communication unit 125 establishes data communication between the angular velocity sensor 100 and an external device. For example, the angular velocity detection value obtained by the digital signal processing unit DSP-B 123 is read from the RAM 121 and is transmitted via the communication terminal 126 to a predetermined value. To the external device. In addition, the communication unit 125 receives a power saving (low power consumption) mode switching signal (transition instruction signal or cancellation instruction signal) of the acceleration sensor 100 from the external device via the communication terminal 126. Here, the communication unit 125 is a digital communication interface, for example, and may be a serial communication bus such as a 3-wire SPI bus or a 2-wire I2C bus. The above-described RAM 121 is a random access memory having a plurality of storage areas configured by, for example, SRAM (Static Random Access で Memory), and is a digital signal processor DSP-A122 or digital signal processor DSP-B123. The processed calculation result can be stored, or a value in the middle of the calculation can be temporarily stored.

The power supply control unit 141 includes a plurality of circuits such as the above-described capacitance detection unit 110 that receive a voltage supplied from an external power supply (for example, a vehicle-mounted battery) (not shown) provided outside the angular velocity sensor 100 via the power supply input terminal 130. It controls the operating state of the

voltage regulators

131, 132, 134 and 135 that convert to the operating voltage of the block.

Here, the voltage regulator 131 converts the voltage supplied from the external power source into the operating voltage of the capacitance detection unit 112 and the temperature sensor 113, and supplies the converted voltage to the capacitance detection unit 112 and the like. In addition, the voltage regulator 132 converts the voltage supplied from the external power source into the operating voltage of the capacitance detection unit 110 and the drive signal generation unit 111, and supplies the converted voltage to the capacitance detection unit 110 and the like. The voltage regulator 134 converts the voltage supplied from the external power source into the operating voltage of the RAM 121, the digital signal processing unit DSP-A 122, the communication unit 125, and the power source control unit 141, and supplies the converted voltage to the RAM 121 and the like. To do. The voltage regulator 135 converts the voltage supplied from the external power source into the operating voltage of the digital signal processing unit DSP-B123 and the ROM 124, and supplies the converted voltage to the digital signal processing unit DSP-B123.

When the communication unit 125 receives an instruction to shift to the power saving mode from the external device and, accordingly, receives an operation stop instruction signal of each voltage regulator from the digital signal processing unit DSP-A 122, the power control unit 141 receives the voltage regulator 132. The

voltage regulators

131 and 135 are in an operation stop state while the operation is in the operation state, and the voltage to the circuit blocks (capacitance detection unit 112, temperature sensor 113, digital signal processing unit DSP-B123, and ROM 124) connected to the

voltage regulators

131 and 135 is stopped. Stop supplying.

In addition, when the communication unit 125 receives a power saving mode release instruction signal from an external device and accordingly receives an operation return (startup) instruction signal of each voltage regulator from the digital signal processing unit DSP-A 122. Then, the

voltage regulators

131 and 135 are set in an operating state, and the voltage supply to the circuit blocks connected to them is resumed.

The voltage supply to each circuit block by the control of each voltage regulator is mainly controlled by the digital signal processor DSP-A122. FIGS. 2 and 3 specifically describe the processing flow when the digital signal processing unit DSP-A shown in FIG. 1 shifts to the power saving mode and cancels the power saving mode, respectively.

As shown in FIG. 2, when the communication unit 125 receives a transition instruction signal (switching signal) to the power saving mode from the external device during the transition to the power saving mode (S201), the digital signal processing unit DSP-A 122 Then, a processing stop instruction signal is output to the digital signal processor DSP-B123 (S202). When the digital signal processing unit DSP-B123 receives the processing stop instruction signal from the digital signal processing unit DSP-A122, the digital signal processing unit DSP-B123 stops the operation after a series of processing sequences is completed (S203). After confirming that the operation of the digital signal processor DSP-B 123 is stopped, the digital signal processor DSP-A 122 outputs an operation stop instruction signal for the

voltage regulators

131 and 135 to the power supply controller 141 (S204). Further, the digital signal processing unit DSP-A 122 outputs a power saving mode transition completion notification instruction signal to the communication unit 125 (S205). When the power supply control unit 141 receives the operation stop instruction signal of the

voltage regulators

131 and 135 from the digital signal processing unit DSP-A 122, the power supply control unit 141 sets the

voltage regulators

131 and 135 to the operation stop state. Further, when the communication unit 125 receives the power saving mode transition completion notification instruction signal from the digital signal processing unit DSP-A 122, the transition to the power saving mode of the angular velocity sensor 100 is completed for an external device (for example, a microcomputer) or the like. Notify you.

On the other hand, as shown in FIG. 3, when canceling the power saving mode, when the communication unit 125 receives a power saving mode canceling instruction signal (switching signal) from an external device (S301), the digital signal processing unit DSP-A122. Outputs an operation return (startup) instruction signal of the

voltage regulators

131 and 135 to the power supply control unit 141 (S302). Thereafter, after the voltage supply to the digital signal processor DSP-B123 is resumed (S303), the digital signal processor DSP-A122 performs the processing sequence of the digital signal processor DSP-B123 at a timing synchronized with its own processing sequence. Is resumed (S304). Further, the digital signal processing unit DSP-A 122 outputs a power saving mode release completion notification instruction signal to the communication unit 125 (S305). When the communication unit 125 receives the power saving mode release completion notification instruction signal from the digital signal processing unit DSP-A 122, the communication unit 125 informs the external device (for example, a microcomputer) that the release of the power saving mode of the angular velocity sensor 100 has been completed. Notice.

As described above, in the angular velocity sensor 100 according to the first embodiment, a plurality of voltage regulators, particularly circuit blocks that need to maintain voltage supply during the power saving mode (circuit blocks necessary to maintain the resonance vibration of the angular velocity sensor element 101). And the voltage regulator connected to the circuit block capable of stopping the voltage supply in the power saving mode, and the resonance of the angular velocity sensor element 101 of the angular velocity sensor 100 based on an external instruction signal for shifting to the power saving mode. The voltage regulator is selectively stopped so that the voltage is supplied only to the circuit block necessary for the processing for maintaining the vibration, and the voltage supply to the circuit block required for maintaining the resonance vibration of the angular velocity sensor element 101 is continued. The voltage supply to other circuit blocks is stopped. As a result, while maintaining the power saving mode state and reducing the power consumption in the power saving mode, the return time of the sensor function when the power saving mode is released can be shortened, and the desired angular velocity (physical quantity) can be precisely defined. Can be detected.

In addition, among the plurality of circuit blocks constituting the angular velocity sensor 100, the voltage supply to each circuit block by the control of each voltage regulator is a circuit block (the angular velocity sensor element 101 of the angular velocity sensor element 101) that needs to maintain the voltage supply in the power saving mode. By controlling the digital signal processor DSP-A122, which is one of the circuit blocks required to maintain the resonance vibration, the voltage supply to each circuit block is reliably controlled in the power saving mode in which the power consumption is reduced. can do.

Second Embodiment
FIG. 4 shows an internal configuration of a second embodiment of an angular velocity sensor as a physical quantity detection device according to the present invention. The second embodiment shown in FIG. 4 is different from the first embodiment shown in FIG. 1 in that two power inputs are provided, a voltage regulator is connected to one system, and a MOS switch is inserted to the other system. The other points are the same as in the first embodiment. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

4 includes two power input terminals 130A and 301A, and

voltage regulators

131A and 132A are connected only to one power input terminal 130A. The angular velocity sensor 100A having such a configuration separates, for example, an analog circuit power source and a digital circuit power source, and independently supplies a voltage to each circuit. According to such a configuration, noise generated in the digital circuit can be prevented from leaking into the analog circuit through the power supply line. In addition, since the digital circuit is not easily affected by fluctuations in the power supply voltage, power can be directly supplied to the circuit block without using a voltage regulator. In the angular velocity sensor 100A having such a configuration, the MOS switch 302A is inserted in the power supply line connected to the digital signal processor DSP-B (physical quantity calculator) 123A and the ROM 124A that can stop the voltage supply in the power saving mode, By turning off the MOS switch 302A in the power saving mode, the same effects as those of the first embodiment can be realized.

Specifically, in the angular velocity sensor 100A of the second embodiment, the power control unit 141A, the RAM 121A, the digital signal processing unit DSP-A 122A, and the communication unit 125A, which are digital circuits, are connected to the external via the power input terminal 301A. Voltage is supplied directly from the power supply. Further, a MOS switch 302A is inserted into a power supply line connected to the digital signal processor DSP-B123A and the ROM 124A, and the digital signal processor DSP-B123A and the ROM 124A which are digital circuits are connected via a power input terminal 301A and the MOS switch 302A. A voltage is supplied from an external power source.

Similarly to the angular velocity sensor 100 of the first embodiment described above, a voltage is supplied from an external power source to the capacitance detection unit 112A and the temperature sensor 113A, which are analog circuits, via a power input terminal 130A and a voltage regulator 131A. . In addition, a voltage is supplied from an external power source to the capacitance detection unit 110A and the drive signal generation unit 111A, which are analog circuits, via a power input terminal 130A and a voltage regulator 132A.

The power supply control unit 141A controls the operating state of the

voltage regulators

131A and 132A and the on / off of the MOS switch 302A, and the communication unit 125A receives a transition instruction signal from the external device to the power saving mode, and accordingly digital signal processing When the operation stop instruction signal of each voltage regulator is received from the unit DSP-A 122A, the voltage control unit 141A outputs the operation stop instruction signal to the voltage regulator 131A, and the voltage regulator 131A is turned on while the voltage regulator 132A is in the operation state. The operation is stopped, and voltage supply to the circuit blocks (capacitance detector 112A and temperature sensor 113A) connected to them is stopped. In addition, the power supply control unit 141A turns off the MOS switch 302A and stops the voltage supply to the circuit blocks (digital signal processing unit DSP-B 123A, ROM 124A) connected thereto.

When the communication unit 125A receives a power saving mode cancellation instruction signal from an external device, and the power supply control unit 141A receives an operation return (startup) instruction signal of each voltage regulator from the digital signal processing unit DSP-A 122A, the voltage The regulator 131A is set to the operating state, the MOS switch 302A is turned on, and the voltage supply to the circuit blocks connected thereto is resumed.

Thus, in the angular velocity sensor 100A of the second embodiment, two power inputs are provided, a voltage regulator is provided only in one system, and a MOS switch is provided in the other system. However, the voltage regulator is selectively stopped so that the voltage is supplied only to the circuit block necessary for the process of maintaining the resonance vibration of the angular velocity sensor 100A based on the external instruction signal for transition to the power saving mode. The power switch mode is switched on and off, and the voltage supply to the circuit blocks required to maintain the resonance vibration of the angular velocity sensor element 101 is continued, and the voltage supply to the other circuit blocks is stopped, so that the power saving mode state is established. Reduced sensor function recovery time when canceling power saving mode while maintaining and reducing power consumption during power saving mode Rukoto can, can finely detect the desired angular velocity (physical quantity).

The present invention is not limited to the first and second embodiments described above, and includes various modifications. For example, the first and second embodiments described above have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of the embodiment.

Also, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

100 angular velocity sensor 101 angular velocity sensor element (sensor element)
102

Vibrator

104, 105

Electrode

106, 107

Fixed electrode

108, 109 Fixed electrode 110 Capacitance detection unit (vibration direction displacement amount detection unit)
111 Drive signal generation unit (drive unit)
112 Capacity detector (Coriolis force displacement detector)
113 Temperature sensor 120 Bus line 121 RAM
122 Digital signal processor DSP-A (drive control value calculator)
123 Digital signal processor DSP-B (physical quantity calculator)
124 ROM
125 communication unit 126 communication terminal 130

power input terminals

131, 132, 134, 135 voltage regulator 141 power control unit 301A power input terminal 302A MOS switch

Claims

A physical quantity detection device that detects a physical quantity using a sensor element having a vibrator,
The physical quantity detection device includes a plurality of circuit units including a communication unit that receives a switching signal related to transition to or cancellation of a power saving mode, and a power supply control unit that controls voltage supply to the plurality of circuit units. ,
The power supply control unit continues supplying a voltage to a circuit unit required for maintaining resonance vibration of the sensor element among the plurality of circuit units when the communication unit receives a signal for instructing transition to a power saving mode. In addition, a physical quantity detection device characterized in that voltage supply to other circuit units is stopped.
The circuit unit required for maintaining the resonance vibration of the sensor element includes the communication unit, a drive unit that drives the sensor element to vibrate, and a vibration direction displacement amount detection unit that detects a displacement amount in the vibration direction of the sensor element. The physical quantity detection device according to claim 1, further comprising: a drive control value calculation unit that calculates a drive control value of the sensor element with respect to the displacement detected by the vibration direction displacement detection unit. .
The power supply control unit receives an operation stop instruction signal from the drive control value calculation unit when the communication unit receives a shift instruction signal to shift to a power saving mode, and supplies a voltage to the other circuit units. The physical quantity detection device according to claim 2, wherein the physical quantity detection device is stopped.
The other circuit unit calculates a physical quantity from a Coriolis force displacement amount detection unit that detects a displacement amount due to Coriolis force of the transducer of the sensor element, and a displacement amount detected by the Coriolis force displacement amount detection unit. The physical quantity detection device according to claim 2, further comprising:
When the communication unit receives a transition instruction signal to the power saving mode, the drive control value calculation unit transmits a processing stop instruction signal to the Coriolis force displacement amount detection unit, and the Coriolis force displacement amount detection unit is When the processing stop instruction signal is received from the drive control value calculation unit, the operation is stopped after a series of processing sequences is completed, and the drive control value calculation unit stops the operation of the Coriolis force displacement amount detection unit. After confirming, the operation stop instruction signal is transmitted to the power supply control unit, and the power supply control unit receives the operation stop instruction signal from the drive control value calculation unit and receives the Coriolis force displacement amount detection unit and the physical quantity calculation unit. The physical quantity detection device according to claim 4, wherein voltage supply to the power supply is stopped.
The power supply control unit stops the voltage supply to the other circuit units by stopping the operation of a voltage regulator disposed between the external power supply and the other circuit units. The physical quantity detection device according to claim 1.
The power control unit stops voltage supply to the other circuit units by turning off a MOS switch disposed between the external power source and the other circuit units. The physical quantity detection device according to claim 1.
The communication unit transmits a transition completion notification or a cancellation completion notification to an external device when the transition or cancellation of the physical quantity detection device to a power saving mode is completed. Physical quantity detection device.
2. The physical quantity detection device according to claim 1, wherein the physical quantity detection device includes a plurality of external input terminals for supplying voltages to the plurality of circuit units.
The physical quantity according to claim 9, wherein the plurality of external input terminals include an external input terminal connected to a digital circuit and an external input terminal connected to an analog circuit among the plurality of circuit units. Detection device.