JP4928875B2 - Sensor module - Google Patents

Description

  The present invention relates to a sensor module having a plurality of sensors such as a magnetic sensor and a motion sensor.

  In Patent Document 1, when geomagnetism is measured using a geomagnetic sensor, the horizontal component of geomagnetism is detected and divided into two component voltage output signals by magnetic detection coils orthogonal to each other, and calculation is performed. A technique for performing correction processing in consideration of values is disclosed.

  In Patent Document 2, in a portable terminal including a magnetic sensor and a tilt sensor, the first tilt angle obtained from the tilt sensor is once again based on information on the elevation angle calculated based on the output of the magnetic sensor. A technique related to a mobile terminal is disclosed, in which the second inclination accuracy is obtained by performing a calculation.

  In Patent Document 3, in a geomagnetic sensor having a geomagnetic detection module for detecting geomagnetism and a module for detecting a tilt angle, an azimuth angle is calculated based on the obtained tilt angle and data from a database in which a constant is set in advance. A technique for calculating is disclosed.

  Patent Document 4 is intended to increase the sensitivity of a magnetic sensor. The magnetic sensor is formed using a TMR element or a GMR element, and is disposed on one surface of the element so that the coercive force is higher than the coercive force of the magnetic layer. The present invention relates to a technique of providing a soft magnetic film for magnetic field sensing that is low and whose anisotropy axis is set independently of the anisotropy axis of a magnetic layer.

JP-A-10-132568 JP 2006-38464 A JP 2006-170997 A JP 2002-207071 A

  In recent years, mobile terminals have been improved in functionality and performance, and mobile phones equipped with a so-called navigation function for guiding to a desired position based on map information are also rapidly spreading. Many of these mobile phones are often equipped with two types of sensors: a geomagnetic sensor that detects geomagnetism, which is a weak magnetic field, and a motion sensor such as an acceleration sensor and a gyro sensor.

However, the strength of geomagnetism is generally very weak at 0.3 to 0.5 Oe. In order to detect extremely weak geomagnetism with high accuracy in this way, it is important to determine how to process the signal obtained from the detection element while improving the characteristics of the detection element itself. Become.
In general, since the geomagnetic sensor detects only the horizontal direction of the geomagnetic vector, in the case of a mobile phone having the navigation function as described above, an acceleration sensor is also used in order to detect the tilt angle. Both output signals are used to satisfy the required functions.

  However, in the case of using such a sensor together, the signal output from the acceleration sensor detects not only the inclination angle but also the acceleration depending on the direction when the user is walking. There is a problem of lacking.

  Therefore, it is desired to detect a signal with very weak intensity such as geomagnetism with high sensitivity and high accuracy by performing signal processing complementary to the tilt angle information. That is, in a sensor module having a plurality of sensors such as a magnetic sensor and a motion sensor, high-precision detection can be performed by applying predetermined signal processing to the output obtained from each sensor without depending on the high-precision of the element itself. I want to

On the other hand, Patent Document 1 includes signal calibration calculation means for detecting a horizontal component of geomagnetism by dividing it into two component voltage output signals by magnetic detection coils orthogonal to each other and calibrating the voltage output signal. A correction value is calculated by inputting to a microcomputer, and correction is made to the azimuth angle data.
However, this means is a technique that is insufficient in terms of high-accuracy detection because it only performs correction calculations based on information from only the geomagnetic sensor.

In Patent Document 3, both a geomagnetism detection module and a tilt angle detection module are provided, and an azimuth angle using data recorded in a database in which constants for reflecting the influence of geomagnetism due to the depression angle are set in advance. A technique for recalculating the above has been proposed.
However, this means is characterized in that the above-described calculation work is performed a predetermined number of times, but considering that the usage situation is used in various ways, the number of calculations is set in advance. In other words, it is unavoidable that the number of operations is excessive or insufficient, and it is not an efficient signal processing method.

Further, in Patent Document 2, in a portable terminal having a geomagnetism measuring means and an inclination angle measuring means, the first inclination angle obtained from the inclination angle measuring means is calculated based on the output of the geomagnetism measuring means. A technique relating to a mobile terminal is disclosed in which the second inclination accuracy is obtained by performing calculation again based on information on the elevation angle.
This Patent Document 2 uses the information of one measuring means to recalculate the tilt angle obtained by the tilt angle measuring means based on the output obtained by the geomagnetic measuring means, and uses the information of one measuring means as the value of the other measuring means. It is a technology that reflects.
However, Patent Document 2 determines the calculation contents of the motion sensor based on the information of the magnetic sensor or the calculation contents of the magnetic sensor based on the information of the motion sensor depending on the output of each detection means. No technical content has been disclosed, and it can be said that there is no disclosure of information in both directions. Furthermore, this technique performs preset recalculation, and it can be said that the technique of performing optimal recalculation in that case in real time is not disclosed.

  Therefore, an object of the present invention is to be very weak like geomagnetism or the like in a sensor module having a plurality of sensors such as a magnetic sensor and a motion sensor by mutually utilizing the signals obtained from each sensor and processing signals. It is to provide a technique capable of detecting even a strong signal with high accuracy and high efficiency.

  According to the first aspect of the present invention, there is provided a magnetic sensor that outputs an electrical signal according to the magnitude of an external magnetic field, a motion sensor that outputs an electrical signal according to movement, and an electrical signal output from each of the sensors. An arithmetic processing unit that performs a predetermined calculation based on the signal, a determination unit that determines a degree of change in the output signal of one of the two sensors, and the other sensor according to the determination result And a calculation content determining means for determining the calculation contents by the calculation processing means.

  According to a second aspect of the present invention, in the sensor module according to the first aspect, the arithmetic processing means performs an arithmetic operation for integrating electrical signals output from the sensors, and the arithmetic content determining means. Determines the number of times of computation for summing up the output signals from the computation processing means for the other sensor according to the determination result.

  According to a third aspect of the present invention, in the sensor module according to the second aspect, the calculation content determination means is an exercise speed or an exercise determined from the determination of the degree of change in the output signal by the determination means. The number of integrations is determined by the degree of change in direction.

  According to a fourth aspect of the present invention, in the sensor module according to the third aspect, the calculation content determination means indicates that the determination result indicates that the output signal of the magnetic sensor has a relatively large change in magnetism. In some cases, the number of integrations by the arithmetic processing means is relatively increased for the motion sensor.

  According to a fifth aspect of the present invention, in the sensor module according to the third or fourth aspect, the calculation content determining means indicates that the determination result indicates that the output signal of the magnetic sensor has a relatively large change in magnetism. In this case, the number of integration by the arithmetic processing means is relatively reduced with respect to the motion sensor.

  According to a sixth aspect of the present invention, in the sensor module according to any one of the first to fifth aspects, the magnetic sensor is a magnetoresistive element.

  According to a seventh aspect of the present invention, in the sensor module according to the sixth aspect, the magnetoresistive element is a TMR (Tunneling Magneto Resistance) element.

  The invention according to claim 8 is the sensor module according to claim 6 or 7, wherein the magnetoresistive elements are three-dimensionally arranged so as to detect magnetism in directions of two or more axes.

  According to a ninth aspect of the present invention, in the sensor module according to the eighth aspect, the magnetoresistive element is formed on an inclined surface.

  A tenth aspect of the present invention is the sensor module according to any one of the first to ninth aspects, wherein the motion sensor is an acceleration sensor and / or a gyro sensor.

  According to the first and second aspects of the present invention, it is possible to perform signal processing of the output signal of the sensor most suitable for the use situation at that time, and to obtain highly accurate information very efficiently. It becomes possible.

  According to the third to fifth aspects of the present invention, it is possible to easily obtain high-precision magnetic information by a process without waste while saving energy, and by performing sufficient signal processing without being influenced by disturbance. It is possible to achieve both high-accuracy magnetic information.

  According to the sixth aspect of the present invention, it is possible to reliably obtain highly accurate magnetic information while being a sensor module that can be driven with essentially less energy.

  According to the seventh aspect of the invention, essentially high sensitivity and high accuracy magnetic information can be reliably obtained with less power consumption.

  According to the eighth aspect of the present invention, it is possible to realize a sensor module that can shorten the power supply circuit wiring, has small energy loss, is small and lightweight, and can obtain magnetic information in all necessary directions. .

  According to the ninth aspect of the present invention, the sensor module can be realized by a relatively simple manufacturing process, and a low-cost and highly reliable sensor module can be realized.

  According to the tenth aspect of the present invention, it is possible to reliably obtain information related to movement with less energy consumption.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram of electrical connection of a sensor module device according to an embodiment of the present invention. The sensor module 1 is mounted on, for example, a portable terminal. The sensor module 1 includes a magnetic sensor 11 that outputs an electrical signal according to the magnitude of an external magnetic field as a detection unit, and a motion sensor, in this example, an acceleration sensor 12 that detects the moving speed and the moving direction and outputs an electrical signal. (A gyro sensor may be used, or an acceleration sensor and a gyro sensor may be used together), and an arithmetic processing unit 13 that performs a predetermined calculation based on electrical signals output from the sensors 11 and 12; The calculation result is compared with the data recorded in the memory 15 to determine what calculation processing should be performed as the next step, and the calculation processing device 13 follows the determination result of the determination device 14. And a display unit 16 for performing final calculation and displaying final output information.

  In such a sensor module 1, processing for determining the calculation content of the acceleration sensor 12 based on the output signal from the magnetic sensor 11 in accordance with the change in the output signal from the magnetic sensor 11 and the output signal from the acceleration sensor 12. On the contrary, a process of determining the calculation content of the magnetic sensor 11 based on the output signal from the acceleration sensor 12 is performed.

Next, a specific operation of the sensor module 1 will be described with reference to FIG. First, the output electrical signals of the magnetic sensor 11 and the acceleration sensor 12 are processed by the processing unit 13 according to a predetermined number of integrations. When the result is determined by the determination device 14 and it is determined that the degree of signal change from the acceleration sensor 12 is greater than a preset value, the integration is performed in the electric signal processing step from the magnetic sensor 11. Increase the number of times and perform recalculation processing. At this time, the magnetic sensor 11 may continue to perform normal arithmetic processing.
Thereby, even when the degree of signal change from the acceleration sensor 12 is large, that is, when it is assumed that the environment change of the user is large, it is possible to obtain highly accurate magnetic information following the change.

FIG. 3 illustrates the opposite case. In other words, in the example of FIG. 3, the output electrical signals of the magnetic sensor 11 and the acceleration sensor 12 are processed according to a predetermined number of integrations, the result is determined by the determination device 14, and the degree of signal change from the acceleration sensor 12 Is determined to be smaller than a preset value. In this case, recalculation is performed by reducing the number of integrations in the step of processing the electric signal from the magnetic sensor 11.
Thereby, highly accurate magnetic information can be obtained efficiently with the minimum number of integrations.

  So far, the processing method for determining the recalculation contents of the output signal of the magnetic sensor 12 based on the output signal of the acceleration sensor 11 has been described. On the contrary, the acceleration sensor based on the output signal of the magnetic sensor 12 has been described. Processing for determining the recalculation contents of the eleven output signals may be performed.

  Conventionally, as the magnetic sensor 11, a magnetoresistive change element (MR element), a magnetic impedance element (MI element), a flux gate sensor, and the like have been generally used. Tunneling Magneto Resistance) element is used.

The TMR element has a structure in which a thin insulating layer is sandwiched between two magnetic layers. The direction of the magnetic field of one magnetic layer is fixed, and the magnetic field of the other magnetic layer is changed according to an external magnetic field. It has a structure. At this time, the magnetic field strength is determined by utilizing the phenomenon that the resistance when the current flows in the film thickness direction varies greatly depending on whether the magnetic field directions of the two magnetic layers are parallel to each other or anti-parallel. It can be detected with high sensitivity.
Since the TMR element has a structure in which a current flows due to an electron tunneling phenomenon, the electric resistance is high, and a large voltage can be obtained even with a very small current. Therefore, the TMR element can be basically operated and detected with energy saving.
In this embodiment, since geomagnetic sensors represented by TMR elements and the like are arranged three-dimensionally so as to correspond to geomagnetism of two or more axes (as shown in FIG. 1, for X, Y, and Z axes). Each is positioned), and magnetic information in all directions as well as in the horizontal direction can be obtained.

  Furthermore, by forming these magnetic sensors on an inclined surface, it is easy to make them monolithic. In this respect, the wiring length when electrically connecting each element to the arithmetic processing unit 13 and other circuit devices can be shortened, and as a result, a circuit configuration with less loss can be realized. Compared with a method of three-dimensionally using a mounting technique, it is possible to realize a highly reliable sensor module that is much more energy saving and easy to miniaturize.

Next, the contents of the processing of the present embodiment described with reference to FIGS. 2 and 3 will be described in detail.
FIG. 4 is a flowchart for explaining the signal processing of this embodiment. In the present embodiment, an example in which a magnetic sensor (geomagnetic sensor) 11 and an acceleration sensor 12 are combined will be described. First, output results of the geomagnetic sensor 11 and the acceleration sensor 12 are obtained (steps S1 and S2). Then, as a result of comparing the obtained output result with the data in the memory 15 recorded in advance by the determination device 14 (step S3), when it is determined that the amount of change in acceleration is larger than normal (step S4). In response to this, the arithmetic processing unit 13 re-calculates the output of the geomagnetic sensor 11 under the condition that the number of integrations of the geomagnetic sensor 11 is increased, for example, twice the normal number (step S5), and the averaging process is performed. After being performed (step S6), it is displayed on the display device 16 together with the output signal of the geomagnetism subjected to the averaging process in the same manner (step S7).

Thus, even under conditions where the amount of change in acceleration is large, by increasing the number of integrations of the geomagnetic sensor 11, highly accurate detection can be realized following a large change in usage conditions.
In this case, the reference signal for performing the arithmetic processing in steps S1 to S4 may be used as the output signal of the geomagnetic sensor 11. That is, the detection means of the geomagnetic sensor 11 and the acceleration sensor 12 are caused to function, and the respective output results are obtained. At this time, if it is determined that the change in the output signal from the geomagnetic sensor 11 is larger than that in the normal state, it means that the surrounding magnetic environment has changed greatly. , That is, by increasing the number of integrations and recalculating, it is possible to obtain highly accurate acceleration information following intense movement.

FIG. 5 is a flowchart for explaining the signal processing of this embodiment. This example will be described using an example in which the geomagnetic sensor 11 and the acceleration sensor 12 are combined. First, output results of the geomagnetic sensor 11 and the acceleration sensor 12 are obtained (steps S11 and S12). As a result of comparing the obtained output result with the data in the memory 15 recorded in advance by the determination device 14 (step S13), when it is determined that the amount of change in acceleration is smaller than normal (step S14), In response to this, the arithmetic processing unit 13 performs the recalculation based on the output of the geomagnetic sensor 11 under the condition that the number of times of accumulation of the geomagnetic sensor 11 is reduced, for example, a normal half (step S15), and the averaging process (Step S16), and display on the display device 16 together with the output signal of the geomagnetism subjected to the averaging process in the same manner (step S17).
As described above, when the acceleration change amount is small, it is possible to detect geomagnetism with necessary and sufficient accuracy even if the number of integrations is reduced.

  In this case, the reference signal for performing the arithmetic processing in steps S11 to S14 may be used as the output signal of the geomagnetic sensor 11. That is, the detection means of the geomagnetic sensor 11 and the acceleration sensor 12 are caused to function, and the respective output results are obtained. At this time, if it is determined that the change in the output signal from the geomagnetic sensor 11 is smaller than that in the normal state, it means that the surrounding magnetic environment has not changed so much. High-accuracy acceleration information can be obtained even if processing, that is, the number of integrations is reduced and recalculated.

It is a block diagram of the electrical connection of the sensor module which is one embodiment of this invention. It is explanatory drawing explaining operation | movement of a sensor module. It is explanatory drawing explaining operation | movement of a sensor module. It is a flowchart explaining operation | movement of a sensor module. It is a flowchart explaining operation | movement of a sensor module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor module 11 Magnetic sensor 12 Acceleration sensor 14 Determination means 15 Integrated content determination means

Claims (10)

A magnetic sensor that outputs an electrical signal according to the magnitude of the external magnetic field;
A motion sensor that outputs electrical signals in response to movement;
Arithmetic processing means for performing a predetermined calculation based on an electrical signal output from each sensor;
Determination means for determining the degree of change in the output signal of one of the sensors;
Calculation content determination means for determining the calculation content by the calculation processing means for the other sensor according to the determination result;
Sensor module equipped with. The arithmetic processing means performs an operation of integrating electric signals output from the sensors,
2. The sensor module according to claim 1, wherein the calculation content determination means determines the number of times of calculation for adding output signals from the calculation processing means for the other sensor according to the determination result.   The calculation content determination means determines the number of integrations according to the degree of change in motion speed or motion direction determined from the determination of the degree of change in the output signal by the determination means. Sensor module.   The calculation content determination means relatively increases the number of integrations by the calculation processing means for the motion sensor when the determination result indicates that the output signal of the magnetic sensor has a relatively large change in magnetism. The sensor module according to claim 3.   The calculation content determination means relatively reduces the number of integrations by the calculation processing means for the motion sensor when the determination result indicates that the output signal of the magnetic sensor has a relatively large change in magnetism. The sensor module according to claim 3 or 4.   The sensor module according to claim 1, wherein the magnetic sensor is a magnetoresistive element.   The sensor module according to claim 6, wherein the magnetoresistive element is a TMR (Tunneling Magneto Resistance) element.   The sensor module according to claim 6 or 7, wherein the magnetoresistive elements are three-dimensionally arranged so as to detect magnetism in directions of two or more axes.   The sensor module according to claim 8, wherein the magnetoresistive element is formed on an inclined surface. The sensor module according to claim 1, wherein the motion sensor is an acceleration sensor and / or a gyro sensor.

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