JP2016161366A - Angular velocity sensor and method for diagnosing operation of sensor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angular velocity sensor that can minimize errors of a temperature correction by directly using temperature information on a sensor element as a main cause for temperature change and can increase the accuracy.SOLUTION: An angular velocity sensor 10 includes: a sensor element 1 for detecting an angular velocity; and an LSI3 with a circuit for processing signals output from the sensor element 1. The sensor element 1 is made of a material presenting such characteristics that a natural frequency makes a constant change to temperatures, and the LSI3 has an oscillator 2 for making the sensor element 1 oscillate based on the natural frequency and temperature correction means 4 for correcting temperatures based on temperature information obtained by the frequencies of outputs of the oscillator 2 monitored.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an angular velocity sensor and a sensor element operation diagnosing method, and more particularly to an angular velocity sensor and the like that can minimize an error due to temperature correction and improve accuracy.

  Angular velocity sensors are sensors that measure rotational speed, and are used for car navigation, automobile, robot posture control, camera shake correction for cameras, and the like, and their applications are expanding. Especially in automobile applications, there are movements used for ADAS and automatic driving. In this case, there are cases where higher accuracy is required than in conventional applications. In particular, there is a high demand for temperature change, and it is necessary to improve the accuracy of temperature correction.

  Sensor elements and circuit components are examples of the temperature change in the angular velocity sensor. Usually, the temperature characteristics of the sensor element are larger and the influence is larger. When correcting the temperature change of the angular velocity sensor, a temperature sensor is used. Many temperature sensors utilize the temperature characteristics of a diode provided in an LSI that performs signal processing. In addition, there are cases where a temperature sensitive element such as an NTC thermistor is used for a circuit board or the like.

  Conventionally, patent applications have been made regarding angular velocity sensors and temperature correction. For example, in Patent Document 1 described below, as an apparatus capable of detecting an angular velocity with a temperature corrected without using a temperature sensor, the input / output characteristics of the angular velocity sensor are stored in a memory for each temperature, and the stop detection unit stops the vehicle. When detected, the determination unit determines an input / output characteristic in which the angular velocity sensor output and the zero point output coincide with each other when the stop of the vehicle is detected among the input / output characteristics stored in the memory, A configuration is disclosed in which the angular velocity is obtained by correcting the output of the angular velocity sensor based on the input / output characteristics previously determined by the determination unit.

Japanese Patent Application Laid-Open No. 8-278140 “Angular Velocity Detector for Moving Body”

  When a temperature sensor is used by using a temperature sensitive element such as an NTC thermistor on a circuit board, there are many cases where the sensor element and the temperature sensor are separated from each other. Therefore, the temperature of the sensor element and the temperature sensor depends on the surrounding environment. Differences are likely to occur. On the other hand, the LSI and the sensor element are often arranged in the same relatively narrow space, so that a temperature difference is less likely to occur. However, if a rapid temperature change still occurs, the temperature between the sensor element and the LSI is low. Differences can occur.

  When temperature correction is performed based on the temperature sensor, if a temperature difference occurs between the sensor element and the temperature sensor, the temperature correction is shifted due to the temperature difference, resulting in an error. Therefore, if the temperature of the sensor element, which is the main cause of the temperature change, can be directly read, the error due to correction should be minimized.

  Therefore, the problem to be solved by the present invention is to eliminate the problems of the prior art and to directly use the temperature information of the sensor element which is the main factor of the temperature change, thereby minimizing the error due to temperature correction and enabling high accuracy. Provide an angular velocity sensor and the like.

  As a result of studying the above problems, the inventor of the present application has a sensor element that detects an angular velocity, an oscillation circuit that oscillates at the natural frequency of the sensor element, and an LSI that includes a circuit that processes a signal output from the sensor element. , The natural frequency of the sensor element changes at a constant rate with respect to temperature, and the LSI can obtain temperature information by monitoring the frequency of the output of the oscillation circuit, and the angular velocity sensor can perform temperature correction based on the temperature information As a result, it has been found that the problem can be solved, and based on this, the present invention has been completed. That is, the invention claimed in the present application, or at least the disclosed invention, as means for solving the above-described problems is as follows.

[1] A sensor element that detects an angular velocity and an LSI that includes a circuit that processes a signal output from the sensor element, and the sensor element has a characteristic that the natural frequency changes with temperature. The LSI includes an oscillation circuit that oscillates the sensor element at its natural frequency, and a temperature correction unit that performs temperature correction based on temperature information obtained by monitoring the frequency of the output of the oscillation circuit. An angular velocity sensor comprising:
[2] The sensor element is made of a material having a characteristic that the natural frequency changes with a constant inclination with respect to the temperature, and the sensor element is self-oscillated to perform signal processing on the natural frequency of the oscillation. The angular velocity sensor according to [1], which can be used as
[3] The angular velocity sensor according to [1] or [2], wherein the LSI is provided with frequency counting means for obtaining the temperature information.
[4] The angular velocity sensor according to [3], wherein the frequency counting means is a reference oscillator.

[5] The angular velocity sensor according to [1] or [2], wherein the LSI is provided with F / V conversion (frequency-voltage conversion) means for obtaining the temperature information.
[6] The angular velocity sensor according to any one of [1] to [5], further comprising an adjustment unit that adjusts variation in information for temperature correction.
[7] The angular velocity sensor according to any one of [1] to [6], wherein the operation state of the sensor element can be diagnosed by monitoring the temperature information.
[8] A sensor element operation diagnosing method, wherein the temperature information is monitored in the angular velocity sensor according to any one of [1] to [6] to determine an operation state of the sensor element.

  Since the angular velocity sensor and the sensor element operation diagnosis method of the present invention are configured as described above, according to this, it is possible to directly recognize the temperature of the sensor element that is the main cause of the temperature change. By performing temperature correction based on the obtained temperature information, errors due to temperature correction can be minimized, and the angular velocity sensor can be highly accurate.

  Further, according to the present invention, since the operation of the sensor element can be confirmed by monitoring the obtained temperature information, it is possible to perform a failure diagnosis of the sensor.

It is a conceptual diagram which shows the basic composition of the angular velocity sensor of this invention. It is a conceptual diagram which shows another basic composition of the angular velocity sensor of this invention. It is explanatory drawing which shows the structure of an Example angular velocity sensor. It is a graph which shows the natural frequency temperature change example of a sensor element (lithium niobate). It is a block diagram which shows the circuit structural example of the angular velocity sensor provided with the frequency counter. It is a block diagram which shows the circuit structural example of the angular velocity sensor provided with the F / V conversion circuit.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a conceptual diagram showing the basic configuration of the angular velocity sensor of the present invention. As shown in the figure, the angular velocity sensor 10 includes a sensor element 1 that detects an angular velocity, and an LSI 3 that includes a circuit that processes a signal output from the sensor element 1, and the sensor element 1 has a natural frequency with respect to temperature. The LSI 3 is based on temperature information obtained by monitoring the oscillation circuit 2 that oscillates the sensor element 1 at its natural frequency, and the frequency of the output of the oscillation circuit 2 being monitored. The main configuration is to include temperature correction means 4 for performing temperature correction.

  With this configuration, in the angular velocity sensor 10 of the present invention, the sensor element 1 that detects the angular velocity oscillates at the natural frequency by the oscillation circuit 2, and the signal output from the sensor element 1 is subjected to signal processing by the processing circuit in the LSI 3. The LSI 3 monitors the frequency of the output of the oscillation circuit 2 to obtain temperature information, and the temperature correction means 4 performs temperature correction based on the temperature information. Since the sensor element 1 is made of a material having a characteristic that the natural frequency changes with temperature, the output of the oscillation circuit 2 can be temperature information.

  As the above-described constant change that the sensor element 1 has as a characteristic, for example, a characteristic that the natural frequency changes with a certain inclination with respect to the temperature can be used effectively. By processing the output frequency of the oscillation circuit 2 that oscillates at the natural frequency of the sensor element 1 as described above, the angular velocity sensor 10 can function and be used as a temperature sensor. In addition, the inertial sensor of the structure which makes the temperature sensor using the frequency characteristic of a sensor element including the said patent disclosure technique does not exist conventionally.

  As shown in the figure, the angular velocity sensor 10 can be configured such that the LSI 3 is provided with frequency counting means 5 for obtaining temperature information, and specifically, a reference transmitter can be used. With this configuration, the frequency of the output of the oscillation circuit 2 is processed as temperature information by the frequency counting means 5 (reference oscillator).

  FIG. 2 is a conceptual diagram showing another basic configuration of the angular velocity sensor of the present invention. As shown in the figure, the angular velocity sensor 210 of the present invention is characterized in that the LSI 23 is provided with F / V conversion (frequency-voltage conversion) means 26 for obtaining temperature information. In the angular velocity sensor 210 of this configuration, the frequency of the oscillation circuit 22 output is processed as temperature information by the F / V conversion means 26.

  Thus, the oscillation circuit output can be obtained either by the frequency counting means (FIG. 1) or by the F / V conversion means (FIG. 2). A frequency counter can be suitably used as the former, and an F / V conversion circuit can be suitably used as the latter. In addition, any temperature information acquisition (generation) means can be provided with an adjustment means (not shown) for adjusting variations in temperature correction information.

  The angular velocity sensor 10 or the like of the present invention can also diagnose the operating state of the sensor element 1 or the like by monitoring temperature information. That is, by monitoring the temperature information, it can be diagnosed whether the sensor element 1 or the like is operating normally. Such a sensor element operation diagnosis method is also within the scope of the present invention.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this.
FIG. 3 is an explanatory view showing the structure of the embodiment angular velocity sensor. As shown in the figure, the angular velocity sensor 310 includes a sensor element 31 that detects the angular velocity, and an LSI 33 that includes an oscillation circuit that oscillates at the natural frequency of the sensor element 31 and a circuit that processes a signal output from the sensor element 31. It is configured.

  FIG. 4 is a graph showing an example of a natural frequency temperature change of the sensor element (lithium niobate). The sensor element is preferably manufactured using an element whose natural frequency changes with temperature, such as the illustrated lithium niobate. With this configuration, the temperature information of the sensor element 31 itself can be obtained by monitoring the frequency of the output signal of the oscillation circuit that oscillates at the natural frequency of the sensor element 31 provided in the LSI 33, and based on the temperature information. By correcting the temperature, an angular velocity sensor with few errors can be realized.

  FIG. 5 is a block diagram showing a circuit configuration example of an angular velocity sensor having a frequency counter. In the angular velocity sensor of this example, the temperature information is obtained from the frequency of the oscillation circuit 42 output signal oscillated at the natural frequency of the sensor element 41 by the frequency counter 46 every time the output of the reference oscillator 45 provided in the LSI rises. It can be obtained by measuring or the like. In this case, the temperature information is obtained as a digital value.

  FIG. 6 is a block diagram illustrating a circuit configuration example of an angular velocity sensor including an F / V conversion circuit. In the angular velocity sensor of this example, the temperature information is obtained by converting the frequency of the output signal of the oscillation circuit 52 oscillated at the natural frequency of the sensor element 51 from the frequency using the F / V conversion (frequency element-voltage conversion) circuit 56. It can be obtained by converting to voltage. In this case, the temperature information is obtained as an analog voltage.

  Since there are individual differences in the natural frequency of the sensor element, the temperature information obtained varies. In addition, the change rate of the natural frequency has almost no individual difference. However, since the change rate is affected by the natural frequency, the temperature coefficient also varies. For such variations, by providing an arithmetic processing unit and gain adjustment for adjusting these, individual differences in temperature information can be reduced, and accuracy can be ensured when performing temperature correction and the like. In addition, since the operation | movement of a sensor element can be confirmed by monitoring the obtained temperature information, it is as above-mentioned that a failure diagnosis of a sensor can be performed.

  According to the angular velocity sensor and the sensor element operation diagnosis method of the present invention, it is possible to directly recognize the temperature of the sensor element, which is the main cause of the temperature change, and perform temperature correction based on the temperature information obtained from the sensor element. As a result, errors due to temperature correction can be minimized, and the angular velocity sensor can be highly accurate. Therefore, the invention is highly industrially applicable in this field and all related fields.

1, 21, 31, 41, 51 ... sensor elements 2, 22, 42, 52 ... oscillator circuits 3, 23, 33 ... LSI
4, 24 ... temperature correction means 5 ... frequency counting means 10, 210, 310 ... angular velocity sensor 26 ... F / V conversion (frequency-voltage conversion) means 30 ... ceramic package 37 ... LID
38 ... Support base 39 ... Holding resin 43, 53 ... Detection circuit 44 ... Memory 45 ... Reference oscillator 46 ... Frequency counter 47, 57 ... Calculation unit 48 ... Data judgment unit 54 ... Correction circuit 56 ... F / V conversion circuit 58 ... Voltage Determination unit D10, D11 ... temperature data D20, D21 ... temperature correction data

Claims (8)

A sensor element that detects angular velocity and an LSI that includes a circuit that processes a signal output from the sensor element. The sensor element is made of a material having a characteristic that the natural frequency changes with temperature. The LSI includes an oscillation circuit that oscillates the sensor element at its natural frequency, and a temperature correction unit that performs temperature correction based on temperature information obtained by monitoring the frequency of the output of the oscillation circuit. An angular velocity sensor. The sensor element is made of a material having a characteristic that the natural frequency changes with a constant inclination with respect to the temperature. The sensor element can be used as a temperature sensor by self-exciting the sensor element and processing the natural frequency of the oscillation. The angular velocity sensor according to claim 1, wherein The angular velocity sensor according to claim 1, wherein the LSI is provided with frequency counting means for obtaining the temperature information. 4. The angular velocity sensor according to claim 3, wherein the frequency counting means is a reference oscillator. 3. The angular velocity sensor according to claim 1, wherein the LSI is provided with F / V conversion (frequency-voltage conversion) means for obtaining the temperature information. 6. The angular velocity sensor according to claim 1, further comprising an adjusting unit that adjusts variation in temperature correction information. The angular velocity sensor according to any one of claims 1 to 6, wherein the operation state of the sensor element can be diagnosed by monitoring the temperature information. The angular velocity sensor according to claim 1, wherein the temperature information is monitored to determine an operation state of the sensor element.