JP4404364B2 - Compact acceleration geomagnetic detector using magnetic acceleration sensor - Google Patents

Description

The present invention relates to a magnetic acceleration sensor, a small acceleration geomagnetism detection device in which the magnetic acceleration sensor and the geomagnetic sensor, and respective detection circuit units are mounted in the same package.

The conventional magnetic acceleration sensor disclosed in Patent Document 1 will be described in detail with reference to a perspective view illustrating the principle of the conventional magnetic acceleration sensor shown in FIG. Recently, sales or announcements of mobile terminal devices equipped with acceleration sensors have begun. This acceleration sensor detects the acceleration when the casing of the mobile terminal device is moved back and forth and left and right, and is used for the operation of the mobile terminal device. There are acceleration sensors that use changes in piezoresistance, those that use changes in capacitance, and those that use changes in magnetic fields, but the conventional magnetic acceleration sensor 50 that uses changes in magnetic fields according to the present invention. Will be described. A conventional magnetic acceleration sensor 50 shown in FIG. 5 has a detection magnet 53 fixed near the tip of a spring plate 54, a magnetic impedance element 51 arranged perpendicular to the magnetization M, and a bias magnetic field applied to the magnetic impedance element 51. It is comprised from the coil for bias magnetic fields for applying. When there is no acceleration, the magnetic field from the detection magnet 53 detected by the magnetic impedance element 51 is set to be zero. For example, when acceleration is applied in the direction of magnetization M from the outside, the spring plate 54 bends in the direction opposite to the magnetization M, and the magnetic field detected by the magneto-impedance element 51 changes from zero. Detect acceleration as a change in impedance.

On the other hand, mobile terminal devices have been equipped with a GPS (Global Positioning System) function using an artificial satellite. Positioning by this GPS, the current position can be confirmed, and it is going to be used for the navigation function. For the navigation function, not only the current position information but also the direction information is indispensable. For this reason, a geomagnetic sensor for obtaining the direction information has been mounted.

A GPS and a geomagnetic sensor are required for the navigation system, and if the acceleration information detected by the acceleration sensor is used for the operation of the mobile terminal device, the magnetic acceleration sensor and the geomagnetic sensor are not the same parts, but the same parts. An acceleration geomagnetism detection device mounted on a package is useful for miniaturization of portable terminal devices.

JP 2000-258449 A

However, when the conventional magnetic acceleration sensor 50 is mounted in the same package as the geomagnetic sensor for detecting geomagnetism of about 40 nT, the detection magnet 53 of the magnetic acceleration sensor 50 does not constitute a closed magnetic circuit. In addition, since the magnetic field is not affected by the geomagnetism, the magnetic acceleration sensor 50 is influenced by the geomagnetism detected by the geomagnetic sensor. Although it is necessary to separate from the geomagnetic sensor as much as possible so as not to affect the detection, there is a problem that the package becomes large.

On the other hand, when the conventional magnetic acceleration sensor 50 is mounted in the same package as the geomagnetic sensor for detecting geomagnetism of about 40 nT, if the detected magnetic field of the conventional magnetic acceleration sensor 50 is close to the magnitude of geomagnetism 40 nT, the external In order to block the magnetic field or the geomagnetism, the magnetic acceleration sensor 50 must be covered with a magnetic shield member (not shown). When the magnetic shield member is strongly magnetized with an external magnetic field, the generated magnetic field is There was a problem of disturbing the geomagnetism detected by the sensor.

For detection, a U-shaped magnetic circuit is formed via a gap between two leaf springs and a soft magnetic material yoke supported by the leaf spring so as to be displaced in the direction opposite to the acceleration in the detection direction. The magnet and the detection magnet are arranged to detect a magnetic field in a direction perpendicular to the gap length direction, and when there is no acceleration, the magnetic field is zero and the gap length direction. When the acceleration is applied, the same acceleration sensor consisting of the magnetic field detection elements that are located in the length direction of the gap of the magnetic field H is used, and the acceleration sensors for the X, Y, and Z axes are used. A three-axis magnetic acceleration sensor, each leaf spring of which is fixed to each surface of the same block at right angles to each other, and Z-axis acceleration sensor as viewed from the Z-axis direction Is the acceleration of the Y axis from the angular position of the X axis acceleration sensor In small acceleration geomagnetism detection device using the magnetic type acceleration sensor that will be located within 90 degrees of the angle range of up to the angular position of the sensor, the small acceleration geomagnetism detection device, the same magnetic field detection element using three respectively The three-axis Z-axis acceleration sensor as viewed from the Z-axis direction is arranged at an angular position of 45 degrees from the angular position of the X-axis acceleration sensor to the angular position of the Y-axis acceleration sensor. and geomagnetic sensor of the sensor and three-axis, Ri Do from each detection circuit, the magnetic type acceleration sensor of the three axes, the acceleration sensor of the Z axis is on a diagonal line of the rectangle of the package, the acceleration sensor of the Z axis Is arranged in the package so that the magnetic circuit is located on one end side of the package on the diagonal line, while the three-axis geomagnetic sensor is replaced with the three-axis magnetic acceleration sensor. Each of the X-axis acceleration sensor, the Y-axis acceleration sensor, and the Z-axis acceleration sensor are arranged adjacent to each other in the diagonal direction of the package on the other end side of the diagonal line of the package. each magnetic circuit Ru disposed farthest position viewed from the geomagnetic sensor of the three axes.

There is an effect that it is possible to provide a small acceleration geomagnetism detection device in which the magnetic acceleration sensor, the geomagnetic sensor, and the respective detection circuits are mounted in the same package.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of a three-axis magnetic acceleration sensor according to the present invention. The three-axis magnetic acceleration sensor 1 is an X-axis acceleration sensor 2 fixed to each surface of a block 5 perpendicular to each other. And a Y-axis acceleration sensor 3 and a Z-axis acceleration sensor 4. The Z-axis acceleration sensor 4 as viewed from the Z-axis direction in the plan perspective view of the acceleration geomagnetism detection device package of the present invention shown in FIG. Are arranged at an angular position of 45 degrees from the X-axis acceleration sensor 2 between the X-axis acceleration sensor 2 and the Y-axis acceleration sensor 3. Incidentally, the acceleration sensor 2 in the X-axis, the acceleration sensor 3 in the Y-axis, the acceleration sensor 4 of the Z-axis be possible to use the same ones, the face of the block 5 for fixing each differ by is there.

In order to describe the acceleration sensor in more detail, the X-axis acceleration sensor 2 shown in FIG. 3 will be described. The X-axis acceleration sensor 2 includes a plate spring 21 fixed to the block 5, a substrate 23 fixed to the tip 21a of the plate spring 21, a detection magnet 22a fixed to the substrate 23, and the detection a magnet 22a, a yoke 22b of the two soft magnetic material forming a magnetic circuit 22 of the U-shaped with a gap 22d of a length g of the gap shown in FIG. 2, the yoke 22c of the soft magnetic material, wherein On the substrate (not shown) on which the block 5 is fixed, the magnetic detection element 24 is arranged at a position where the magnetic field detected when the acceleration is zero is zero. As the magnetic detection element 24, a Hall element, an MR element, and a magnetic impedance element can be used. However, the MR element and the magnetic impedance element require a coil that generates a bias magnetic field. The same applies to the Y-axis acceleration sensor 3 and the Z-axis acceleration sensor 4, and a description thereof will be omitted.

FIG. 2 is a perspective view of a magnetic circuit made of a magnetic field generation detection magnet of the X-axis acceleration sensor of the present invention, and a graph showing the relationship between the position X of the magnetic detection element and the magnetic field shown in FIG. The operation of the X-axis acceleration sensor of the present invention will be described. When there is no acceleration, the magnetic detection element 24 for detecting the magnetic field in the GV direction perpendicular to the direction GP of the gap length g leaking into the gap 22d of the magnetic circuit 22 is the center of the gap 22d in the length direction . in a position where X shown in 6 is zero, the detection magnetic field of the magnetic sensor 24 is zero, to connect to the magnetic detection element 24, detection circuit section 1a shown in FIG. 4 does not output the acceleration detection signal . Next, when acceleration in the X-axis direction is applied, the leaf spring 21 to which the magnetic circuit 22 is fixed by the base 23 is displaced in the −X-axis direction along the GP, and the magnetic detection element 24 has a gap shown in FIG. When coming to the position X from the center of 22d, the magnetic detection element 24 detects the magnetic field H, and the detection circuit unit 1a outputs an acceleration detection signal corresponding to the acceleration. Corresponding to the acceleration range to be detected, the spring force of the leaf spring is set so that the variable range of X becomes X range, XL, in which the change of the magnetic field H with respect to the displacement X is almost linear as shown in FIG. The Incidentally, when the acceleration is applied in any direction, because the acceleration sensor of only each axis component of each axis of the acceleration is detected, Y-axis, for the acceleration sensor of the Z axis is similar, the description Omitted.

FIG. 4 is a plan perspective view of the package of the acceleration geomagnetism detection device of the present invention. The acceleration geomagnetism detection device 10 has the three-axis Z-axis acceleration sensor shown in FIG. The magnetic acceleration sensor 1 arranged at an angular position of 45 degrees from the angular position of the acceleration sensor to the angular position of the Y-axis acceleration sensor and its detection circuit unit 1a, and an acceleration detection unit 11 that outputs an acceleration detection signal; consists geomagnetic sensor 8 three-axis and the detection circuit unit 8a, is composed of a geomagnetic detector 12 that outputs geomagnetic detection signal, the magnetic type acceleration sensor 1, acceleration in the X-axis of the magnetic type acceleration sensor 1 the magnetic circuit 22 of the sensor 2 is brought close to 13a surface of the package 13, the magnetic circuit 32 of the acceleration sensor 3 in the Y-axis is brought close to 13b surface of the package 13, the acceleration sensor 4 of the Z-axis Located on the diagonal C-C of the package 13 as viewed from the axis, the magnetic circuit 44 of the acceleration sensor 4 of the Z-axis is brought close to the ridge line 13c of the package 13 of one end side of the diagonal line C-C, the The geomagnetic sensor 8 is disposed on the package 13 , while the geomagnetic sensor 8 is adjacent to the triaxial magnetic acceleration sensor 1 in the direction of the diagonal line CC of the package and the other end side of the package 13 along the diagonal line CC. The magnetic circuits 22, 32, and 42 of the X-axis acceleration sensor 2, the Y-axis acceleration sensor 3, and the Z-axis acceleration sensor 4 are farthest from the 3-axis geomagnetic sensor 8. Become a position. Since the leaf spring 41 of the Z-axis acceleration sensor is displaced in a direction perpendicular to the paper surface, a hole for escaping the Z-axis acceleration sensor 4 is formed in the substrate 14 (not shown).

Since the detection magnets 22a, 32a, and 42a of the acceleration geomagnetism detection device 10 constitute magnetic circuits by the yokes 22b and 22c, 32b and 32c, and 42b and 42c, respectively, the detection magnets 22a, 32a, and 42a The magnetic field generated and leaked, which is about 10 times larger than the geomagnetism, does not spread compared to the case where the detection magnet is a single unit, and is limited to the vicinity of the gaps 22d, 32d and 42d of the magnetic circuits 22, 32 and 42, respectively. Therefore, it does not reach the position of the magnetic detection element of the geomagnetic sensor 8 away from the position of the magnetic detection elements 24, 34, 44 of the acceleration sensor 1 . Further, Hall elements, MR elements, and magneto-impedance elements can be used as the magnetic detection elements 24, 34, and 44. Even in MR elements and magneto-impedance elements that require a bias magnetic field, the magnetic flux is the gaps 22d, 32d, The magnetic field returns from 42d through the yokes 22b and 22c of the magnetic circuits 22, 32 and 42, 32b and 32c, and 42b and 42c, and does not reach the position of the magnetic detection element of the geomagnetic sensor. does not affect the terrestrial magnetism detection performance, the package of the acceleration geomagnetism detector 10 and the magnetic type acceleration sensor 1 mounted on the same package as the geomagnetic sensor 8 of the present invention was mounted in the same package, the conventional magnetic type acceleration package acceleration geomagnetism detection device of the sensor and a geomagnetic sensor or another package, The implemented, can be small in comparison with the acceleration sensor utilizing a change in the change or capacitance of the piezo resistors, the package of the acceleration geomagnetism detection device comprising a geomagnetism sensor.

As indicated by the foregoing detailed description, the magnetic three-axis acceleration sensor using the same acceleration sensor to the acceleration sensor of each axis, the magnetic field detection element and the same magnetic field detecting element used in the magnetic acceleration sensor since the can be implemented in three identical packages geomagnetic sensor for three axes using, for use in each of the functions of the navigation function for operation by moving the housing horizontally and vertically back and forth, a small low-cost An acceleration geomagnetism detection device can be provided to a mobile terminal device.

1 is a perspective view of a triaxial magnetic acceleration sensor of the present invention. It is a perspective view of the magnetic circuit which consists of a magnet for detection of magnetic field generation of the X-axis acceleration sensor of the present invention. It is a perspective view of the X-axis acceleration sensor of the present invention. It is a plane perspective view of the package of the acceleration geomagnetism detection device of the present invention. It is a perspective view for showing the principle of the conventional magnetic type acceleration sensor. It is a graph which shows the position X of a magnetic detection element, and the relationship of the magnetic field.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 3-axis magnetic acceleration sensor 10 Acceleration geomagnetic detection apparatus 2 X-axis acceleration sensor 3 Y-axis acceleration sensor 4 Z-axis acceleration sensors 21, 31, 41 Leaf springs 22, 32, 42 Magnetic circuit comprising detection magnets 22a, 32a, 42a Detection magnets 22b, 22c, 32b, 32c, 42b, 42c Yoke 22d, 32d, 42d Gap 24, 34, 44 Magnetic field detection element

Claims (1)

For detection, a U-shaped magnetic circuit is formed via a gap between two leaf springs and a soft magnetic material yoke supported by the leaf spring so as to be displaced in the direction opposite to the acceleration in the detection direction. The magnet and the detection magnet are arranged to detect a magnetic field in a direction perpendicular to the gap length direction, and when there is no acceleration, the magnetic field is zero and the gap length direction. When the acceleration is applied, the same acceleration sensor consisting of the magnetic field detection elements that are located in the length direction of the gap of the magnetic field H is used, and the acceleration sensors for the X, Y, and Z axes are used. A three-axis magnetic acceleration sensor, each leaf spring of which is fixed to each surface of the same block at right angles to each other, and Z-axis acceleration sensor as viewed from the Z-axis direction Is the acceleration of the Y axis from the angular position of the X axis acceleration sensor In small acceleration geomagnetism detection device using the magnetic type acceleration sensor that will be placed within 90 degrees of the angle range of up to the angular position of the sensor, the small acceleration geomagnetism detection device, the same magnetic field detection element using three respectively The three-axis Z-axis acceleration sensor as viewed from the Z-axis direction is arranged at an angular position of 45 degrees from the angular position of the X-axis acceleration sensor to the angular position of the Y-axis acceleration sensor. and geomagnetic sensor of the sensor and three-axis, Ri Do from each detection circuit, the magnetic type acceleration sensor of the three axes, the acceleration sensor of the Z axis is on a diagonal line of the rectangle of the package, the acceleration sensor of the Z axis Is arranged in the package so that the magnetic circuit is located on one end side of the package on the diagonal line, while the three-axis geomagnetic sensor is replaced with the three-axis magnetic acceleration sensor. Each of the X-axis acceleration sensor, the Y-axis acceleration sensor, and the Z-axis acceleration sensor are arranged adjacent to each other in the diagonal direction of the package on the other end side of the diagonal line of the package. each magnetic circuit compact acceleration geomagnetism detection device using the magnetic type acceleration sensor, wherein Rukoto disposed farthest position viewed from the geomagnetic sensor of the three axes.