WO2007148450A1

WO2007148450A1 - Acceleration and magnetic direction detecting composite sensor and acceleration and magnetic direction detecting device

Info

Publication number: WO2007148450A1
Application number: PCT/JP2007/052278
Authority: WO
Inventors: Kosuke Uga; Takashi Hatanai; Mitsuo Bito; Munemitsu Abe; Tatsumi Fujiyoshi; Nobuaki Haga
Original assignee: Alps Electric Co., Ltd.
Priority date: 2006-06-22
Filing date: 2007-02-08
Publication date: 2007-12-27

Abstract

[PROBLEMS] To provide a small, lower-cost sensor for detecting an acceleration and a magnetic direction with high accuracy with small burden on the control computing section and a detecting device. [MEANS FOR SOLVING PROBLEMS] An acceleration and magnetic direction detecting composite sensor device comprises a base (1), three magnetism detecting elements (2, 3, 4) fabricated on the base (1), a cross-shaped elastic beam section (5) fixed at its one end to the base (1) through a fixing section not shown, a weight section (6) attached to the central portion of the elastic beam section (5), and an exciting coil (7) formed on the lower surface of the weight section (6). The device further comprises a control computing section (8) for controlling supply of the exciting current to the exciting coil (7), receiving the outputs of the magnetism detecting elements (2, 3, 4), and computing the acceleration and the magnetism direction according to the outputs of the received magnetism detecting elements (2, 3, 4).

Description

Specification

Composite sensor for detecting acceleration and magnetic direction, and acceleration and magnetic direction detecting device

Technical field

The present invention relates to a composite sensor for detecting acceleration and magnetic orientation, and an acceleration and magnetic orientation detection device using the same.

Background art

In recent years, for example, mobile terminal devices such as mobile phones are known in which an acceleration sensor and a geomagnetic sensor are mounted. The acceleration sensor is used, for example, for switching between pedometers and applications, and the geomagnetic sensor is used, for example, for detecting a direction in a navigation system.

Conventionally, as this type of acceleration sensor, a permanent magnet is attached to the free end of a cantilever-type rigid body with one end fixed, and a magnetic sensor is installed in an area covered by the magnetic field of the permanent magnet, and is elastic. A sensor that detects changes in the magnetic field due to body deformation with a magnetic sensor (for example, [, Special Article References]), mems, and a support made by using microelectronic mechanical system technology J A beam portion supported by the support portion, a weight portion connected to the beam portion, and a pedestal joined to the support portion, and forming an electrostatic capacity between the support portion and the pedestal. There have been proposed ones provided with electrodes to be provided, or ones provided with a piezoelectric element such as a piezo element on the support (for example, see Patent Document 2). In addition, as a geomagnetic sensor, an amorphous wire and a detection coil wound around the amorphous wire (for example, see Patent Document 1), a sensor using a magnetoresistive element or a Hall element have been proposed. (For example, refer to Patent Document 2.) ₀ Patent Documents 1 and 2 also disclose a technique in which an acceleration sensor and a geomagnetic sensor are integrated to form a composite sensor for detecting acceleration and magnetic orientation. .

Patent Document 1: Japanese Patent Laid-Open No. 2005-195369

Patent Document 2: JP-A-11-160349

Disclosure of the invention Problems to be solved by the invention

However, the techniques described in Patent Documents 1 and 2 have various problems as described below when configuring a composite sensor for detecting acceleration and magnetic orientation. That is, (a) magnetic sensors are required as many as the number of detection axes of acceleration to be detected and the number of detection axes of magnetic azimuth, so that the sensor unit is expensive and large.

[0005] (b) Since acceleration calculation and magnetic direction calculation cannot be calculated with the same detection algorithm, a sensor IC or microcomputer for calculating acceleration and magnetic direction calculation is required, and the burden required for developing an arithmetic program is increased. Requires a large and large memory capacity.

[0006] (c) In a composite sensor of a type in which the acceleration sensor includes a permanent magnet, the magnetic field of the permanent magnet included in the acceleration sensor may adversely affect the detection accuracy of the magnetic orientation sensor. In order to detect with high accuracy, it is necessary to correct the detection signal, which complicates the calculation program. In addition, since permanent magnets are used, it is not possible to switch functions such as changing the range of the acceleration detection sensor according to the application.

[0007] (d) In a composite sensor that uses a magnetic sensor with the same detection range as a magnetic sensor for acceleration detection and a magnetic sensor for magnetic orientation detection, the magnetic sensor for acceleration detection becomes too sensitive. Susceptible to external magnetic fields. In order to optimize the sensitivity of the magnetic sensor for acceleration detection, correction of the detection signal is necessary, and the calculation program is complicated.

[0008] The present invention has been made to solve the problems of the related art, and its purpose is to increase the acceleration and the magnetic direction which are small and low cost and reduce the burden on the control calculation unit. An object of the present invention is to provide a composite sensor for detecting acceleration and magnetic azimuth that can be accurately detected, and an acceleration and magnetic azimuth detecting device using the same.

Means for solving the problem

In order to solve the above-mentioned problems, the present invention relates to a composite sensor for detecting acceleration and magnetic orientation, and applies a magnetic field to one to a plurality of magnetic detection elements and to these one to a plurality of magnetic detection elements. An excitation coil and an elastic beam part that supports the excitation coil are provided. [0010] Further, the present invention relates to an acceleration and magnetic azimuth detection device, and supports one or more magnetic detection elements, an excitation coil that applies a magnetic field to these one or more magnetic detection elements, and the excitation coil. A composite sensor for detecting acceleration and magnetic azimuth having an elastic beam portion, and controlling the supply of excitation current to the excitation coil, and inputting the output of the magnetic detection element, and according to the input output of the magnetic detection element And a control arithmetic unit for calculating the acceleration and the magnetic direction.

[0011] In this manner, the caloric velocity includes one or more magnetic detection elements, an excitation coil that applies a magnetic field to the one or more magnetic detection elements, and an elastic beam portion that supports the excitation coil. In addition, when the composite sensor for detecting the magnetic orientation receives the acceleration, the elastic beam part is displaced by the amount corresponding to the magnitude of the acceleration in the direction corresponding to the direction of the acceleration. The posture of the excitation coil supported by the part changes. Therefore

When the exciting coil is energized, the direction and magnitude of the magnetic field generated from the exciting coil with respect to the magnetic detection element changes according to the direction and magnitude of the acceleration. A corresponding level of output can be taken out. The detection range can be easily switched by switching the excitation current. On the other hand, an external magnetic field such as geomagnetism can be calculated as the DC component of the output of the magnetic detection element when the excitation current is applied, and can be obtained as the output value of the magnetic detection element when the excitation current is interrupted. The magnetic orientation can also be detected by using a magnetic detection element used for detecting acceleration. In addition, since acceleration and magnetic orientation are detected using the same magnetic sensing element, the acceleration and magnetic orientation detection algorithms can be made the same, facilitating the development of a computation program and the necessity. The memory capacity can be reduced. Furthermore, since the magnetic field applied by the exciting coil does not become noise when detecting the magnetic orientation, the magnetic orientation can be detected with high accuracy. Since the acceleration detection range can be changed as appropriate by increasing or decreasing the excitation current supplied to the excitation coil, it is not necessary to provide a highly sensitive magnetic detection element, making it less susceptible to external magnetic fields during acceleration detection. Can do.

[0012] Further, according to the present invention, in the acceleration and magnetic orientation detection device having the above-described configuration, the control calculation unit supplies an excitation current to the excitation coil and generates a current from an output of the magnetic detection element. The velocity and magnetic direction are calculated in parallel. According to the powerful configuration, acceleration and magnetic orientation can be measured continuously at the same time, and acceleration that takes a very short time can be detected without omission. In addition, since the calculation time can be reduced, the frequency response of the detection device can be improved.

[0013] Further, the present invention provides the acceleration and magnetic orientation detection device having the above-described configuration, wherein the control calculation unit supplies an AC excitation current to the excitation coil, and calculates an acceleration from an AC component of the output of the magnetic detection element. At the same time, the DC component force is calculated to calculate the magnetic orientation. Thereby, calculation of acceleration and calculation of magnetic direction can be performed using a relatively simple arithmetic program.

[0014] Further, according to the present invention, in the acceleration and magnetic orientation detection device having the above-described configuration, the control calculation unit calculates an acceleration from an output of the excitation coil when an excitation current is supplied to the excitation coil, and the excitation The magnetic azimuth is calculated from the output of the excitation coil when the supply of excitation current to the coil is cut off. According to such a configuration, since the acceleration and the magnetic direction are calculated separately, there is no interaction between the calculation of the acceleration and the calculation of the magnetic direction, and an inspection apparatus that is resistant to disturbance can be obtained.

[0015] Further, according to the present invention, in the acceleration and magnetic direction detection device having the above configuration, the magnetic detection element includes three magnetic detection elements having magnetic detection directions directed in three directions orthogonal to each other. I made it. The powerful configuration makes it possible to detect acceleration and magnetic direction in any direction.

The invention's effect

[0016] According to the present invention, a magnetic field necessary for acceleration detection is applied to one or a plurality of magnetic detection elements using an exciting coil, so that a magnetic detection element necessary for acceleration detection and a magnetic detection necessary for magnetic orientation detection are applied. It can be shared with the elements, and the acceleration and magnetic direction detection device can be reduced in size and cost. In addition, since the acceleration and magnetic orientation can be calculated with the same detection algorithm, the burden on the control calculation unit can be reduced. Furthermore, by controlling the supply of the excitation current to the excitation coil, the magnetic field generated by the excitation coil force can be adjusted as appropriate, so that the acceleration detection range can be changed as appropriate, and at the time of calculation of acceleration and magnetic direction Eliminate noise effects or Can be reduced.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the configuration of the acceleration and magnetic direction detection composite sensor and the acceleration and magnetic direction detection apparatus using the same according to the present invention will be described with reference to FIGS. 1 to 5. FIG. Fig. 1 is a configuration diagram of the acceleration and magnetic orientation detection device according to the embodiment, Fig. 2 is an explanatory diagram showing the direction of the magnetic field generated by the exciting coil and the direction of geomagnetism, and Fig. 3 is when the acceleration in the X or Y direction is received. Fig. 4 is an operation explanatory diagram showing the movement of the composite sensor when it receives acceleration in the Z direction, and Fig. 5 shows the magnetic field generated by the excitation coil and the output of the magnetic detection element. It is a graph figure to illustrate.

As shown in FIGS. 1 and 2, the acceleration and magnetic direction detection device of this example includes a base 1, three magnetic detection elements 2, 3, 4 formed on the base 1, and one end. Of the cross-shaped elastic beam 5 fixed on the base body 1 through a fixing unit (not shown), the weight 6 attached to the center (movable part) of the elastic beam 5, and the weight 6 The excitation coil 7 formed on the bottom surface and the excitation current supply to the excitation coil 7 are controlled and the outputs of the magnetic detection elements 2, 3, and 4 are input. It consists mainly of a control calculation unit 8 that calculates acceleration and magnetic direction according to the output. The composite sensor for detecting acceleration and magnetic orientation according to the present invention includes a base 1, magnetic detection elements 2, 3, 4, an elastic beam portion 5, a weight portion 6, and an excitation coil 7. This composite sensor can be fabricated by mems technology.

The three magnetic detection elements 2, 3, and 4 are oriented in three directions in which the magnetic detection directions are orthogonal to each other, that is, the X direction, the Y direction, and the Z direction in FIGS. As the magnetic detection elements 2, 3, and 4, for example, a magnetoresistive element or a Hall element can be used.

[0020] The elastic beam portion 5 is formed in a cross shape with a plate material having a constant width, and the weight portion 6 is attached to the center portion thereof. As shown in FIG. 4, when the elastic beam portion 5 is deformed so that the weight portion 6 is inclined with respect to the base body 1 and acceleration in the Z direction is applied, as shown in FIG. The elastic beam part 5 is deformed so that the weight part 6 approaches or separates from 1.

[0021] The weight portion 6 is formed by deforming the elastic beam portion 5 when subjected to acceleration, and thus the magnetic detection element 2, This is to increase the displacement of the excitation coil 7 with respect to 3 and 4 to a certain extent to increase the detection sensitivity of the acceleration, and can be omitted when the excitation coil 7 having a necessary weight is used.

[0022] As the exciting coil 7, any known coil such as a wire coil or a thin film coil can be used. When energized, the exciting coil 7 generates a magnetic field in the direction of the winding axis of the exciting coil 7 (direction perpendicular to the exciting coil forming surface of the weight portion 6) as shown in FIG. As described above, when the acceleration is received, the weight portion 6 is deformed in the direction of the acceleration by an amount corresponding to the magnitude of the acceleration, so that the excitation coil 7 applied to each magnetic detection element 2, 3, 4 The generated magnetic field changes. Therefore, the control calculation unit 8 can calculate the direction and magnitude of the acceleration acting on the weight unit 6 from the change in the output of the magnetic detection elements 2, 3, 4. Further, the control calculation unit 8 can calculate the direction and magnitude of an external magnetic field such as geomagnetism from the DC component of the output of each magnetic detection element 2, 3, 4.

[0023] The exciting current supplied from the control calculation unit 8 to the exciting coil 7 can be a direct current or an alternating current. When an alternating current is supplied, the waveform can be a square wave, a triangular wave, a sine wave, or the like. Figure 5 shows the magnetic field generated by the excitation coil 7 and the geomagnetism when the square-wave excitation current is supplied from the control calculation unit 8 to the excitation coil 7, and the combined magnetic field of the magnetic field generated by the excitation coil 7 and the geomagnetism. The output of each magnetic detection element 2, 3 and 4 when receiving each magnetic field is shown. As is apparent from this figure, the magnetic field generated by the exciting coil 7 generated by supplying the excitation current and the outputs of the magnetic detection elements 2, 3, and 4 are square waves corresponding to the excitation current waveform, and are generated by the geomagnetism. The output of the generated magnetic detection elements 2, 3, 4 is a constant value.

Hereinafter, a first example of the acceleration and magnetic direction calculation procedure performed by the control calculation unit 8 will be described with reference to FIG. First, the control calculation unit 8 supplies a square wave excitation current to the excitation coil 7 and generates a magnetic field in the excitation coil 7. A magnetic sensor with sensitivity in the X direction calculates (Xmax—Xmin) Z2 and (Xmax + Xmin) Z2 from its maximum output Xmax and minimum output Xmin, and calculates the AC component Ax and DC component Cx in the X direction. calculate. At the same time, the magnetic sensing element with sensitivity in the Y direction calculates (Ymax—Ymin) Z2 and (Ymax + Ymin) Z2 from its maximum output Ymax and minimum output Ymin, and the AC component Av and Y in the Y direction are calculated. And DC component Cy is calculated. Next, the control calculation unit 8 adds the X-direction AC correction component Ax to the X-direction gain correction coefficient cx X and the X-direction offset correction coefficient β X to add the X-direction acceleration A (X). = Αχ Χ α χ + j8 x is calculated together with the Y-direction AC component Ay in addition to the Y-direction gain correction coefficient ay and Y-direction offset correction coefficient βy. Acceleration A (y) = Ay X ay + j8 y is calculated. Next, the control calculation unit 8 performs the calculation of Equation 1 using the acceleration A (X) in the X direction and the acceleration A (y) in the Y direction obtained previously, and the magnitude of the acceleration IAI and its direction Θ a And calculate. At the same time, the control calculation unit 8 performs the calculation of Equation 2 using the previously obtained DC component Cx in the X direction and DC component Cy in the Y direction to calculate the geomagnetic direction Θc. The gain correction coefficients α χ, ay and offset correction coefficients j8 X, j8 y are obtained in advance from the relationship between the acceleration and the displacement of the excitation coil 7. Further, in the flowchart of FIG. 6, gain correction and offset correction are performed in the same manner as in the calculation of force / acceleration in which gain correction and offset correction at the time of azimuth calculation are omitted.

[Number 1]

Θ a = arctani ⁴

[Equation 2]

Θ c = arctan

C (x)

[0025] According to the calculation procedure of this example, the magnitude and direction of acceleration and the azimuth of geomagnetism can be calculated simultaneously, so that the calculation time can be reduced and the frequency response of the detection device can be improved. . In addition, since the magnitude and direction of acceleration and the direction of geomagnetism can be obtained in the X, Y, and Z directions orthogonal to each other, a highly practical detection device that can be applied to, for example, a navigation system. be able to.

[0026] Hereinafter, a second example of the acceleration and magnetic direction calculation procedure performed by the control calculation unit 8 will be described. This will be described with reference to FIG. The calculation procedure of this example is obtained by passing the output of the magnetic detection elements 2, 3, and 4 through a noise-pass filter and a low-pass filter instead of obtaining the AC component and DC component of the output by calculation. . According to the calculation procedure of this example, the calculation of the output AC component and DC component can be omitted, so the burden on the control calculation unit 8 can be reduced and the frequency response of the detection device can be further improved. Can do.

Hereinafter, a third example of the acceleration and magnetic orientation calculation procedure performed by the control calculation unit 8 will be described with reference to FIG. The calculation procedure of this example is to calculate the magnitude and direction of acceleration while energizing the exciting coil 7 that does not calculate the magnitude and direction of acceleration and the direction of geomagnetism in parallel. It is characterized in that the geomagnetic direction is calculated in the state where the power is not supplied. According to the calculation procedure of this example, acceleration and magnetic direction are calculated separately, so there is no interaction between the calculation of acceleration and magnetic direction, and it is strong against disturbance V and can be an inspection device. .

[0028] The acceleration and magnetic orientation detection composite sensor and the acceleration and magnetic orientation detection device using the same according to the embodiment apply a magnetic field to the magnetic detection elements 2, 3, and 4 using the excitation coil 7. In addition, the magnetic detection element necessary for detecting the acceleration and the magnetic detection element required for detecting the magnetic direction can be shared, and the acceleration and magnetic direction detection device can be reduced in size and cost. Further, as shown in FIGS. 6 to 8, since the acceleration and the magnetic azimuth can be calculated by the same detection algorithm, the burden on the control calculation unit 8 can be reduced. Furthermore, by controlling the supply of the excitation current to the excitation coil 7, the magnetic field generated from the excitation coil 7 can be adjusted as appropriate, so that the acceleration detection range can be appropriately changed, and the acceleration calculation and magnetic direction can be changed. It is possible to eliminate or reduce the influence of noise when calculating.

In the above embodiment, the elastic beam portion 5 is formed in a cross shape made of a plate material having a constant width, but the shape of the elastic beam portion 5 is not limited to this. As illustrated in Fig. 9, it can have various shapes. Fig. 9 (a) shows an embodiment in which the elastic beam portion 5 is formed in a radial shape extending in three directions around the set position of the weight portion 6, and Fig. 9 (b) shows a cantilever as the elastic beam portion 5. FIG. 9 (c) shows an embodiment in which the elastic beam portion 5 is formed with three linear spring members extending spirally from the set position of the weight portion 6. Fig. 9 (d) shows an embodiment in which the elastic beam portion 5 is formed with four triangular plate members, and Fig. 9 (e) shows an embodiment in which the elastic beam portion 5 has four sheets. FIG. 9 (f) shows an embodiment in which a rectangular plate material is formed, and FIG. 9 (f) shows a case in which the elastic beam portion 5 is formed with four linear spring materials extending in four directions from the set position of the weight portion 6. FIG. 9 (g) shows an embodiment in which the elastic beam portion 5 is formed with two linear spring members extending in two directions from the set position of the weight portion 6. FIG.

[0030] In the embodiment, the three magnetic detection elements 2, 3, and 4 having sensitivity in the X direction, the Y direction, and the Z direction are provided. However, the present invention is not limited to this, it can be a single-axis type detection device having only one magnetic detection element, or two axes in which two magnetic detection elements are arranged in two directions perpendicular to each other. This is a type detection device.

Brief Description of Drawings

FIG. 1 is a configuration diagram of an acceleration and magnetic orientation detection device according to an embodiment.

FIG. 2 is an explanatory diagram showing the direction of the magnetic field generated by the exciting coil and the geomagnetism.

FIG. 3 is an operation explanatory diagram showing the movement of the composite sensor when it receives an acceleration in the X direction or the Y direction.

FIG. 4 is an operation explanatory diagram showing the movement of the composite sensor when it receives acceleration in the Z direction.

FIG. 5 is a graph illustrating the generated magnetic field of the exciting coil and the output of the magnetic detection element.

FIG. 6 is a flowchart showing a first example of an acceleration and magnetic orientation detection procedure using the acceleration and magnetic orientation detection device according to the embodiment.

FIG. 7 is a flowchart showing a second example of an acceleration and magnetic orientation detection procedure using the acceleration and magnetic orientation detection device according to the embodiment.

FIG. 8 is a flowchart showing a third example of the acceleration and magnetic orientation detection procedure using the acceleration and magnetic orientation detection device according to the embodiment.

FIG. 9 is a structural diagram showing another example of the composite sensor according to the embodiment.

Explanation of symbols

[0032] 1 substrate

2, 3, 4 Magnetic detector Elastic beam part Weight part Excitation coil Control calculation part

Claims

The scope of the claims

[1] It includes one or more magnetic detection elements, an excitation coil that applies a magnetic field to the one or more magnetic detection elements, and an elastic beam portion that supports the excitation coil. A combined sensor for detecting acceleration and magnetic orientation.

[2] one or more magnetic detection elements, an excitation coil for applying a magnetic field to the one or more magnetic detection elements, an acceleration and magnetic orientation detection composite sensor having an elastic beam portion supporting the excitation coil, and A control arithmetic unit that controls the supply of the excitation current to the excitation coil, inputs the output of the magnetic detection element, calculates the acceleration according to the input output of the magnetic detection element, and calculates the magnetic orientation An acceleration and magnetic orientation detection device characterized by comprising:

[3] The acceleration and magnetic field according to claim 2, wherein the control calculation unit supplies an excitation current to the excitation coil and calculates an acceleration and a magnetic direction in parallel from an output of the magnetic detection element. Orientation detection device.

[4] The control calculation unit supplies an AC excitation current to the excitation coil, calculates acceleration from an AC component of an output of the magnetic detection element, and calculates a magnetic orientation from the DC component. The acceleration and magnetic orientation detection device according to claim 3.

[5] The control calculation unit calculates an acceleration from an output of the magnetic detection element when an excitation current is supplied to the excitation coil, and the magnetic detection when the supply of the excitation current to the excitation coil is cut off. 3. The acceleration and magnetic orientation detection device according to claim 2, wherein the magnetic orientation is calculated from the output of the element.

6. The acceleration and magnetic direction detection device according to claim 2, wherein the magnetic detection element includes three magnetic detection elements whose magnetic detection directions are directed in three directions orthogonal to each other.