JP2010066049A - Magnetic detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic detector which is simple in structure, is easy to manufacture, and can detect a magnetic field with high precision for an external magnetic field. <P>SOLUTION: The magnetic detector 1 includes a magnetic impedance element 3 and a pickup coil 5 for extracting a change in the impedance of the magnetic impedance element 3 as an electric signal. The magnetic impedance element 3 is made longer than a pickup coil arrangement area 6. The pickup coil 5 is arranged in a longitudinal middle part 4 of the magnetic impedance element 3. The magnetic impedance element 3 is provided with electrodes 3a, 3b for applying a signal with a predetermined frequency to the longitudinal middle part 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic detection device using a magnetic impedance element (MI element).

  In general, since a magnetic impedance element (hereinafter referred to as “MI element”) has a characteristic that impedance changes based on a change in an external magnetic field, a magnetic detection device using an MI element is known.

  As this type of technology, Patent Document 1 discloses that electrodes are provided at both ends of an MI element, and magnetism collecting portions are provided at predetermined intervals from each of the end portions of the MI element. It is disclosed that a magnetized magnetic flux is taken out as an electrical signal by an MI element.

JP 2007-93328 A

  However, the technique of Patent Document 1 has a problem that the number of parts is increased and the manufacturing is troublesome because the magnetic flux collecting section is provided separately from the MI element. In particular, the magnetism collecting part is difficult to manufacture because it needs to be insulated from the electrodes of the MI element and at a predetermined interval.

  The present invention has been made paying attention to the above circumstances, and an object thereof is to provide a magnetic detection device that can be easily manufactured with a simple configuration and can detect magnetism with high sensitivity to an external magnetic field.

  The invention described in claim 1 includes a magneto-impedance element and a pickup coil that extracts an impedance change of the magneto-impedance element as an electric signal, and the length of the magneto-impedance element is longer than the pickup coil arrangement region. The pickup coil is arranged in the middle part in the longitudinal direction of the magneto-impedance element, and the magneto-impedance element is provided with an electrode for applying a signal of a predetermined frequency in the middle part in the longitudinal direction.

  The invention described in claim 2 is characterized in that, in the invention described in claim 1, the magneto-impedance element is constituted by arranging a plurality of magneto-impedance element wires in parallel.

  The invention described in claim 3 is the invention according to claim 1 or 2, wherein the magneto-impedance element is characterized in that the linear members are arranged in a substantially circular shape and a gap is provided at both ends. .

  The interval between the end faces of the magneto-impedance element may be 1 / μs (magnetic permeability) mm or more, but the substantially circular angle formed by the magneto-impedance element is 240 degrees or more.

  The invention described in claim 4 is the invention according to any one of claims 1 to 3, wherein the pickup coil arrangement region is a region having a length of 1 to 5% with respect to the length of the magneto-impedance element. It is arranged in that.

  According to the first aspect of the present invention, since the MI element uses the entire longitudinal direction as the magnetism collecting portion, it is not necessary to provide a magnetism collecting member separately. Can detect magnetism.

  In particular, among the MI elements, those having a composition such as Co—Fe—Si—B and Fe—Si—B have high magnetic permeability, and by themselves have a high magnetic flux collecting effect. It is preferable to use an element.

  Manufacture is also easy because only the pickup coil is arranged in the middle part of the long MI element.

  The higher the frequency of the signal applied to the intermediate portion in the longitudinal direction of the MI element, the greater the proportion of the current flowing through the surface due to the skin effect, and the sensitivity can be increased.

  In addition, when a long MI element is a wire (strip), it can be easily bent or deformed, so that it can be deformed according to the installation space or installation location, and the dead space of the installation part can be reduced. .

  According to the invention described in claim 2, since the magnetic flux is captured by the surface of the MI element while having the effect of claim 1, by configuring the MI element with a plurality of MI element wires, The surface area of the MI element can be increased, and the magnetic collection area can be increased. Therefore, the magnetic collection can be further increased.

  According to the third aspect of the present invention, the MI element is provided in a substantially circular shape, and the magnetic flux can be received in all directions, and the magnetic flux collection in the direction can be achieved. Can be reduced.

  According to the invention described in claim 4, the effect described in any one of claims 1 to 3 is achieved, and the coil placement region for the MI element having a certain length can be reduced by taking a long coil region. Since the magnetic flux collection factor of the element decreases and the resistance of the coil also increases, 1 to 5% is preferable in consideration of the overall sensitivity.

  Therefore, by setting the ratio of the length of the coil arrangement region to the length of the MI element to be 1 to 5%, the magnetic flux detection can be further enhanced.

  Embodiments of the present invention will be described below with reference to FIGS. 1 to 3 of the accompanying drawings. FIG. 1 is a plan view showing a schematic configuration of the magnetic detection device according to the first embodiment of the present invention, FIG. 2 is a perspective view of the magnetic detection device according to the first embodiment, and FIG. It is a graph which shows the ratio of the optimal area | region length of the pickup coil with respect to length.

  The magnetic detection device 1 according to the present embodiment is an AC magnetic (so-called radio wave) magnetic detection device.

  As shown in FIG. 1, the magnetic detection device 1 mainly includes an MI element 3 and a pickup coil 5 wound so as to surround the MI element 3. The MI element 3 is a wire and is longer than the winding region 6 of the pickup coil 5.

  In the present embodiment, the length of the MI element is about 40 mm, and the length of the winding region of the pickup coil 5 is about 1 mm.

  Electrodes 3 a and 3 b for applying a signal of a predetermined frequency are provided at the longitudinal intermediate portion 4 of the MI element 3, and the electrodes 3 a and 3 b of the MI element 3 are arranged in the longitudinal direction of the winding region 6 of the pickup coil 5. It is located outside in the direction. The pickup coil 5 is provided with electrodes 5a and 5b for outputting electric signals.

  In the present embodiment, as shown in FIG. 2, in the magnetic detection device 1, an intermediate portion between the pickup coil 5 and the MI element 3 is provided in the resin sealing portion 7, and each terminal 5 a of the pickup coil 5 is provided. 5 b is connected from the resin sealing portion 7 to the connection terminal 11 via the amplifier 9. Similarly, the electrodes 3 a and 3 b of the MI element are also connected to the connection terminal 11 from the resin sealing portion 7 through the amplifier 9.

  The MI element 3, the resin sealing portion 7, the amplifier 9, and the connection terminal 11 are supported by a support member 13 made of a resin film, and a connector 15 is connected to the connection terminal 11. The frequency signal is supplied from 15 to the MI element and the electrical output from the pickup coil 5 is taken out.

  Here, the ratio of the length of the winding region 6 of the pickup coil 5 to the length of the MI element 3 will be described. Assuming that the length of the MI element 3 is constant, as shown in FIG. 3, if the ratio of the length of the winding region 6 of the pickup coil 5 to the MI element 3 is high, the magnetic flux collection is reduced and the pickup coil There is a disadvantage that the resistance R is increased. On the other hand, if the winding area of the pickup coil is too small, the detection sensitivity is lowered. Considering the synthesis sensitivity from such a viewpoint, as shown in FIG. 3, the synthesis sensitivity has a predetermined peak value within a certain range, and the region N including the peak is about 1 to 10%. Preferably, it is 1 to 5%. In the present embodiment, the ratio of the length of the winding region 6 of the pickup coil 5 to the length of the MI element 3 is 2.5%.

  The operation and effect of the magnetic detection device 1 according to the first embodiment will be described. According to the magnetic detection apparatus 1 according to the first embodiment, since the pickup coil 5 is wound around the middle part 4 of the long MI element 3, the MI element 3 has the entire longitudinal direction as a magnetic collecting part. Since it is used directly, it is not necessary to provide a separate magnetic flux collecting member as disclosed in Patent Document 1, and it is possible to detect magnetism with high sensitivity and high sensitivity with a simple configuration.

  Since the pickup coil 5 is simply wound around the middle portion 4 of the long MI element 3, the manufacture is also easy.

  In the present embodiment, since the long MI element is a wire (strand body), it can be easily bent or deformed, so that it can be deformed according to the installation space or installation location. Dead space can be reduced.

  Next, other embodiments of the present invention will be described. In the embodiments described below, the same reference numerals are given to portions having the same operational effects, and detailed description thereof is omitted. In the following description, differences mainly from the above-described first embodiment will be described.

  FIG. 4 shows a magnetic detection device 1 according to the second embodiment. In the second embodiment, the MI element 3 according to the first embodiment is composed of a plurality of MI element wires 3c, 3c, and 3c. In the second embodiment as well, the MI element 3 and the like are supported by the support member 13 as in the first embodiment shown in FIG.

  According to the second embodiment, the same operation and effect as in the first embodiment are obtained, and since the magnetic flux is generally captured by the surface of the MI element 3, the MI element 3 is connected to the plurality of MI element wires 3c. By configuring with 3c and 3c, the surface area of the MI element 3 can be increased, and the magnetism collecting area can be increased. Therefore, the magnetic collection can be further increased.

  The MI element wires 3c, 3c, and 3c are not limited to being arranged in parallel at intervals, but may be arranged in contact with each other. You may do it.

  5 and 6 show a magnetic detection device 1 according to the third embodiment. FIG. 5 is a plan view showing a schematic configuration of the magnetic detection device 1 according to the third embodiment, and FIG. 6 is a plan view showing a state in which the magnetic detection device 1 is mounted on a wristwatch with a radio timepiece function. In the third embodiment, the magnetic detection device 1 is used as a receiving antenna for receiving a TCO (Time Code Output) signal for a radio clock, and the MI element 3 is arranged in a substantially circular shape, but both ends are arranged. The parts are arranged with a gap therebetween.

  In the third embodiment as well, the MI element 3 and the like are supported by the support member 13 as in the first embodiment shown in FIG.

  According to the third embodiment, the same operational effects as those of the first embodiment can be obtained, and the MI element 3 is arranged in a circle along the inner peripheral edge of the watch interior 19. The dead space with respect to the installation site | part of the detection apparatus 1 can be decreased.

  In addition, since the MI element 3 is disposed substantially over the entire circumference, it can receive a magnetic flux from all directions, and can reduce the bias of magnetic collection with respect to the direction.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

  For example, in the first aspect of the invention, the MI element 3 and the pickup coil 5 are not limited to the wire strip, but the MI element 3 is formed in a film shape on the substrate, and the pickup coil is a planar coil (planar coil). It may be what you did.

The magnetic detection device 1 according to the present invention is not limited to receiving a long wave such as a TCO signal, but may be one that receives medium-wave radio waves (for example, AM radio broadcast radio waves) or detects geomagnetism as a direction sensor. .

It is a top view which shows schematic structure of the magnetic detection apparatus which concerns on 1st Embodiment of this invention. 1 is a perspective view of a magnetic detection device according to a first embodiment. It is a graph which shows ratio of the optimal area | region length of a pick-up coil with respect to the length of MI element. It is a top view which shows schematic structure of the magnetic detection apparatus which concerns on 2nd Embodiment of this invention. It is a top view which shows schematic structure of the magnetic detection apparatus which concerns on 3rd Embodiment of this invention. It is a top view which shows the state which mounted the magnetic detection apparatus 1 in the wristwatch with a radio timepiece function.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic detection apparatus 3 MI element 4 Middle direction of MI element 5 Pickup coil 6 Winding area (arrangement area) of pickup coil

Claims (4)

  A magnetic impedance element; and a pickup coil that extracts an impedance change of the magnetic impedance element as an electric signal. The length of the magnetic impedance element is longer than the pickup coil arrangement region, and the pickup coil is intermediate in the longitudinal direction of the magnetic impedance element. And a magneto-impedance element provided with an electrode for applying a signal of a predetermined frequency in the middle in the longitudinal direction.   The magnetic detection device according to claim 1, wherein the magnetic impedance element is configured by arranging a plurality of magnetic impedance element wires in parallel.   3. The magnetic detection device according to claim 1, wherein the magneto-impedance element has linear members arranged in a substantially circular shape and a gap at both ends.   The magnetic detection device according to any one of claims 1 to 3, wherein the pickup coil arrangement region is arranged in a region having a length of 1 to 5% with respect to a length of the magnetic impedance element. .

Images