Parallel fluxgate sensor and manufacturing method thereof

Abstract

To provide a parallel flux gate sensor for suppressing deflection or vibration of a magnetic core.SOLUTION: A parallel flux gate sensor 10 of the present invention has two linear magnetic cores 12 made of a film or wire-shaped magnetic metal and arranged in parallel, each of the magnetic cores 12 is provided with a magnetically exciting coil 14 and a detecting coil 16 in the parallel flux gate sensor 10, and the magnetic core 12 is supported by a support member 20 of a non-magnetic material sized to suppress deflection or vibration.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a parallel fluxgate sensor used as a detection sensor for a device for detecting magnetic foreign matter mixed in clothing, food, etc., and a method for manufacturing the same. [Background technology]

[0002] Fluxgate sensors detect the unidirectional component of a magnetic field by utilizing the magnetic saturation of a high-permeability material. A fluxgate utilizes the high permeability of a soft magnetic material, and high-permeability soft magnetic materials absorb external magnetic fields. For this reason, a coil is wound around the magnetic core of the soft magnetic material, and when a current is passed through the coil to cause magnetic saturation, the absorbed external magnetic field is released. Therefore, when another coil is wound around it as a detection coil and an excitation current is applied, the soft magnetic material repeatedly absorbs and releases the external magnetic field, generating an induced voltage according to the same principle as a transformer. Fluxgate magnetic sensors are capable of detecting even minute static magnetic fields and are therefore used in highly sensitive magnetic sensors (for example, as disclosed in Patent Document 1). Of these, parallel fluxgate sensors have an excitation coil wound around a magnetic core made of a highly magnetically permeable material, and the magnetic core is magnetically saturated by the magnetic field generated by passing current through the excitation coil, so no electrical connection of any kind is required to the magnetic core, and the excitation coil and detection coil (also called pickup coil) have the same shape, which has the advantage of being easy to manufacture. Typically, a magnetic core made of a highly magnetically permeable material such as an amorphous film or wire is held in place in some way, and a coil is wound around it.

[0003] However, because small fluxgate sensors typically have a film or wire-shaped magnetic core, if the holding method is not appropriate, deflection occurs due to the mass of the magnetic core material or the electromagnetic force of an externally applied magnetic field. The stress caused by these deflections affects the magnetostriction characteristics of the magnetic core, which in turn changes the magnetic properties of the magnetic material, causing problems with detecting weak magnetic fields, such as unstable sensor output. Similarly, if the holding method is not appropriate, vibrations applied from the outside or electromagnetic forces applied from the excitation coil will occur in the magnetic core. The vibrations of the magnetic core will cause intermittent deflection in localized areas of the magnetic core, affecting the magnetostriction characteristics of the magnetic core. As a result, the magnetic properties of the magnetic material will change, causing the sensor output to become unstable and hindering the detection of weak magnetic fields. Furthermore, when the magnetic core vibrates, its relative position with respect to the detection magnetic field changes, resulting in noise due to the vibrations of the magnetic core being superimposed on the sensor output, hindering the detection of weak magnetic fields. Furthermore, small parallel fluxgate sensors with magnetic cores made of highly permeable materials such as amorphous film or wire have small components, making alignment difficult during manufacturing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-81300 A Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above-mentioned problems of the conventional technology, the problem to be solved by the present invention is to provide a parallel fluxgate sensor and a manufacturing method thereof that suppresses deflection of the magnetic core due to the mass of the magnetic core material or deflection of the magnetic core due to the electromagnetic force of an externally applied magnetic field, or vibrations applied from the outside or vibrations due to the electromagnetic force applied from an excitation coil. In view of the above-mentioned problems of the prior art, another object of the present invention is to provide a method for manufacturing a parallel fluxgate sensor that allows the parallel fluxgate sensor to be easily manufactured. [Means for solving the problem]

[0006] As a first means for solving the above problems, the present invention provides a parallel fluxgate sensor in which two linear magnetic cores made of a film or wire-shaped magnetic metal are arranged in parallel, and an excitation coil and a detection coil are provided in each of the magnetic cores, The magnetic core is sandwiched between supports of non-magnetic material sized to inhibit flexure or vibration. The excitation coil and the detection coil were inserted from both ends of the support. Only the law of nature, The end of the support is provided with a support piece that is hooked onto the edge of the mounting groove of the sensor component. The present invention aims to provide a parallel fluxgate sensor characterized by the above. According to the first aspect, the support for supporting the magnetic core can suppress deflection or vibration of the magnetic core. The support can also serve as a bobbin around which the excitation coil or the detection coil is wound, or as an attachment guide or holder for the excitation coil or the detection coil wound around an air core. Furthermore, the magnetic core and the support can be easily attached to and aligned with the sensor component such as a substrate.

[0007] As a second means for solving the above problem, the present invention provides a parallel fluxgate sensor according to the first means, characterized in that the magnetic core is sandwiched between supports of equal or larger size in at least part of its length and width. According to the second means, the magnetic core can be securely clamped, and deflection or vibration of the magnetic core can be suppressed.

[0008] As a third means for solving the above-mentioned problems, the present invention provides a parallel fluxgate sensor according to the first or second means, characterized in that the thickness of the support is three or more times larger than the thickness of the magnetic core. According to the third means, the deflection or vibration of the magnetic core can be sufficiently suppressed.

[0010] The present invention is a first method for solving the above problems. 4 As a means of 3 In any one of the above means, the support body is provided with a butting portion protruding in the width direction to align the excitation coil and the detection coil at their mounting positions. The above item 4 According to the above means, the excitation coil and detection coil attached to the support and the magnetic core can be easily aligned.

[0011] The present invention is a first method for solving the above problems. 5 As a means of 4 In any one of the above means, the parallel fluxgate sensor is characterized in that the excitation coil and the detection coil are wound in the same direction and with the same number of turns. The above item 5 According to the above means, the excitation coil and the detection coil can be made into the same component, which prevents the excitation coil and the detection coil from being confused during production, as would occur if the excitation coil and the detection coil were not the same component, and also reduces costs by reducing the number of components.

[0012] The present invention is a first method for solving the above problems. 6 As a means of 5 In any one of the above means, the detection coils provided on the two magnetic cores are connected in parallel. The above item 6 According to the method of (1), when the magnetic core is excited in the opposite direction by the excitation coil, the detection coils are connected in parallel to obtain the average value of the induced electromotive force generated in each detection coil. This cancels out the excitation magnetic field components of the induced electromotive force caused by the magnetic flux change in the two magnetic cores, making it possible to detect the externally applied magnetic field with sufficient accuracy.

[0013] The present invention is a first method for solving the above problems. 7 As a means of 5 In any one of the above means, the detection coils provided on the two magnetic cores are connected in series. The above item 7According to the method of (1), when the magnetic core is excited in the opposite direction by the excitation coil, the detection coils are connected in series to obtain the sum of the induced electromotive forces generated by each detection coil. This cancels out the excitation magnetic field components of the induced electromotive forces caused by the magnetic flux changes in the two magnetic cores, making it possible to detect the externally applied magnetic field with sufficient accuracy.

[0014] The present invention is a first method for solving the above problems. 8 As a means of 7 The object of the present invention is to provide a parallel fluxgate sensor, characterized in that the excitation coil and the detection coil installed on the magnetic core are installed at a distance of 1 / 10 or less of the total length of the magnetic core. The above item 8 According to the above means, the externally applied magnetic field can be detected with sufficient accuracy.

[0015] The present invention is a first method for solving the above problems. 9 As a means of 8 The object of the present invention is to provide a parallel fluxgate sensor, characterized in that the excitation coil and the detection coil are installed within a range of 70% or less of the distance from the longitudinal center of the magnetic core to the end of the magnetic core. The above item 9 According to this means, the externally applied magnetic field can be detected with sufficient accuracy without being affected by the effect of the demagnetizing field generated at the end of the magnetic core.

[0016] The present invention is a first method for solving the above problems. 10 a clamping step of inserting and clamping the magnetic core between supports; a coil mounting step in which an excitation coil and a detection coil are inserted from both ends of the support and moved until they abut against the abutting portion in the center; a mounting step of hooking the support piece of the support onto an edge of the mounting groove of the sensor component and storing the lower part of the support in the mounting groove; The present invention provides a method for manufacturing a parallel fluxgate sensor, which is characterized by having the above-mentioned steps. The above item 10According to this method, the coil to be inserted into the support can be easily aligned by simply butting it against the butting part. Also, when mounting the support on the board, alignment can be easily achieved by simply hooking the support piece protruding from the main body of the support. [Effects of the Invention]

[0017] According to the present invention, the support that supports the magnetic core can suppress deflection or vibration of the magnetic core. The support can also serve as a bobbin around which the excitation coil or the detection coil is wound, or as an attachment guide or holder for the excitation coil or the detection coil wound around an air core. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram of a parallel fluxgate sensor of the present invention. [Figure 2] FIG. [Figure 3] 1 is an explanatory diagram showing the relationship between the inner diameter d of the coil, the width dimension b of the support, and the thickness dimensions (m, l) of the magnetic core and the support. [Figure 4] 1A to 1C are diagrams illustrating the manufacturing process of the parallel fluxgate sensor of the present invention. [Figure 5] FIG. 10 is an explanatory diagram of a modified parallel fluxgate sensor. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A parallel fluxgate sensor and a manufacturing method thereof according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. [Parallel Fluxgate Sensor 10] FIG. 1 is a schematic diagram of a parallel fluxgate sensor of the present invention. FIG. 2 is a front view of the support and magnetic core. As shown, the parallel fluxgate sensor 10 of the present invention comprises two linear magnetic cores 12, each made of a film or wire of magnetic metal, arranged in parallel. Each core 12 is provided with an excitation coil 14 and a detection coil 16. Each magnetic core 12 is supported by a support 20 made of a nonmagnetic material sized to suppress deflection or vibration. The excitation coils 14 are connected in series with opposite polarities, so that when current is applied by a drive power supply 17, the magnetic fields are oriented in opposite directions. The detection coils 16 are connected in parallel or series and are detectable by a detector 18, which detects the magnetic field induced by the excitation current. For example, magnetic field fluctuations caused by a magnetic object passing nearby can be detected.

[0020] (Magnetic core 12) The magnetic core 12 is made of a high-permeability, soft-magnetic amorphous metal and is in the form of a film or wire. The magnetic core 12 is periodically alternately placed in a magnetically unsaturated state (high permeability), a magnetically saturated state (significantly lower permeability than the magnetically unsaturated state), or a state close to magnetic saturation (lower permeability than the magnetically unsaturated state), causing the magnetic core 12 to repeatedly pass and discharge magnetic flux due to the ambient magnetic field passing through the magnetic core 12. This converts the amount of change in the ambient magnetic field into the amount of change in the passage and discharge of magnetic flux, which is then converted into the amount of change in the induced electromotive force of the detection coil 16, thereby making it possible to detect changes in the ambient magnetic field.

[0021] (Support 20) The support 20 is a resin plate made of a non-magnetic material that sandwiches the magnetic core 12. As an example of the material for the support 20, a glass epoxy plate can be used, taking into consideration its low cost, ease of availability, and ease of processing. The support 20 is It is also possible to use a combination of a resin plate, which is a non-magnetic material, and an insulating resin material formed into a resin mold by molding, coating, or other techniques. Regarding the thickness of the support 20, if the support 20 is too thick, the coil diameters of the excitation coil 14 and the detection coil 16 become large, making it impossible to miniaturize the entire sensor. On the other hand, if the support 20 is too thin, not only is the strength weak and it is not possible to suppress the bending or vibration of the magnetic core 12, but it also becomes difficult to sandwich the magnetic core 12 between the support 20 and assemble it on a substrate. Therefore, the thickness of the support 20 of the present invention is set to be at least three times greater than the thickness of the magnetic core 12. The magnetic core 12 is typically made of an amorphous film or the like, and the Young's modulus E(a) of these amorphous films is typically around 100 GPa. On the other hand, the support 20 is typically made of a glass epoxy plate, for example, and the Young's modulus E(g) is typically around 20 GPa. Therefore, if the thickness of the support 20 is set to be at least three times greater than the thickness of the magnetic core 12, the amount of strain when external stress is applied is reduced to less than half, and the effect of using the support becomes significant. This allows for sufficient suppression of deflection or vibration of the magnetic core 12. Furthermore, at least a part of the length and width of the support 20, in other words, the maximum length, is set to be equal to or greater than the same so as to be able to suppress deflection or vibration of the magnetic core 12. 3 is an explanatory diagram showing the relationship between the coil inner diameter d, the width dimension b of the support, and the thickness dimensions (m, l) of the magnetic core and support. Here, the inner diameters of the excitation coil 14 and detection coil 16 are d, the width dimension b of the support 20 is l, and the thickness dimension m of the magnetic core 12. The thickness dimension when the magnetic core 12 is sandwiched between the supports 20 is x. It is necessary to satisfy x = 2l + m and l > 3m. Also d 2 ≧b 2 +x 2 It is recommended to set it so that

[0022] The support 20 has support pieces 22A and 22B at both ends that fit over the edges of the mounting grooves in the circuit board. The support pieces 22A and 22B are integrally formed with the support 20, with a hook-like shape formed by partially cutting out the lower end of the support 20 when viewed from the front. The distance between the lower side surfaces of the hook-shaped support pieces 22A and 22B is set shorter than the length of the mounting grooves in the circuit board. When the support 20 is attached to the circuit board, the upper ends of the support pieces 22A and 22B fit over the edges of the mounting grooves and the lower ends of the support pieces 22A and 22B fit within the mounting grooves. The lengths of the support pieces 22A and 22B at both ends vary, with the longer piece 22B and the shorter piece 22A being longer and shorter, respectively, to allow for identification of the mounting orientation of the support 20. For example, the longer piece 22B is positioned closer to the detection coil 16, and the shorter piece 22A is positioned closer to the excitation coil 14. This allows for easy alignment of the mounting orientation (orientation) of the magnetic core 12 and the support 20 to the circuit board, preventing incorrect installation.

[0023] The support 20 is provided with a butt portion 24 that protrudes in the width direction to align the excitation coil 14 and detection coil 16 with their mounting positions. The butt portion 24 is a portion that protrudes vertically (in the width direction) from the center position of the support 20 and is formed integrally with the support 20. By providing the butt portion 24, when attaching the excitation coil 14 and detection coil 16 to the magnetic core 12 held by the support 20, if the excitation coil 14 is inserted from one end of the support 20 and the detection coil 16 is inserted from the other end of the support 20, the excitation coil 14 and detection coil 16 will butt against the central butt portion 24. By inserting the coils until they butt against the butt portion 24 in this way, alignment can be easily achieved.

[0024] (Excitation coil 14 and detection coil 16) The excitation coil 14 and the detection coil 16 are wound in the same direction and with the same number of turns. This allows the excitation coil 14 and the detection coil 16 to be made into the same component, which prevents confusion between the excitation coil 14 and the detection coil 16 during production, as would occur if the excitation coil 14 and the detection coil 16 were not the same component, and also reduces costs by reducing the number of components.

[0025] The ratio of the distance (gap ΔL) between the excitation coil 14 and detection coil 16 installed on the magnetic core 12 to the length dimension (L0) of the magnetic core 12 is set to a distance of 1 / 10 or less of L0, thereby enabling detection of an externally applied magnetic field with sufficient accuracy. Furthermore, the excitation coil 14 and detection coil 16 are placed within a range of 70% or less of the distance (L0 / 2) from the longitudinal center O of the magnetic core 12 to the end of the magnetic core 12. This allows the externally applied magnetic field to be detected with sufficient accuracy without being affected by the effect of the demagnetizing field generated at the end of the magnetic core.

[0026] The detection coils 16 installed on each of the two magnetic cores 12 are connected in parallel or in series. As a result, when the magnetic cores 12 are excited in opposite directions by the excitation coils 14, if the detection coils 16 are connected in parallel, the average value of the induced electromotive forces generated in each detection coil 16 is obtained, and if the detection coils 16 are connected in series, the sum of the induced electromotive forces generated by each detection coil 16 is obtained. Therefore, in either the parallel or series connection, the excitation magnetic field components of the induced electromotive forces caused by changes in magnetic flux in the two magnetic cores 12 cancel each other out, making it possible to detect the externally applied magnetic field with sufficient accuracy. 5A and 5B are explanatory diagrams of a modified parallel fluxgate sensor. In the parallel fluxgate sensor 10A shown in Fig. 5A, the length and width of the support 20 and the magnetic core 12 are set to be the same except for the abutting portion 24. In the parallel fluxgate sensor 10B shown in FIG. 1B, the length of the support 20 is greater than that of the magnetic core 12, and the width is set to the same length as that of the magnetic core 12 in part (both ends and inside the coil). The parallel fluxgate sensor 10C shown in Fig. 1C has the same shape of the support piece 22, and the support 20 is formed so that part of the length dimension is larger than the magnetic core 12. In addition, a recess 40 is provided in part of the longitudinal direction of the support 20. The recess 40 is a sight hole through which the magnetic core 12 held by the support 20 can be seen, and it is possible to check for positional deviation such as protrusion. In addition, the abutment portion 24 may be formed only on the upper part.

[0027] [Manufacturing method] A method for manufacturing the parallel fluxgate sensor of the present invention having the above-described configuration will be described below. Figure 4 is a manufacturing process diagram of the parallel fluxgate sensor of the present invention.

[0028] (Process of clamping the support and magnetic core) A film or wire-shaped magnetic core 12 and a support 20 made by processing a glass epoxy plate and having long and short support pieces 22A, 22B and an abutment portion 24 are prepared (see FIG. 4(1)). The magnetic core 12 is inserted between the two supports 20 and aligned in the length and width directions so that the magnetic core 12 does not protrude from the supports 20.

[0029] (Coil installation process) Coils are inserted from both ends of the support 20 that holds the magnetic core 12 (see FIG. 4(2)). Support pieces 22A and 22B at both ends of the support 20 have different protruding lengths, so the sides into which the excitation coil 14 and detection coil 16 are inserted can be determined arbitrarily. The inserted excitation coil 14 and detection coil 16 are moved until they abut against the abutment portion 24 provided in the center of the support 20. This allows for easy alignment.

[0030] (mounting process on the board) The support 20 on which the excitation coil 14 and detection coil 16 are assembled is mounted in the mounting groove 32 of the substrate 30 (see FIG. 4(3)). The mounting groove 32 of the substrate 30 is set in advance to a size that will allow the main body and coil of the support body 20, excluding the support pieces 22A and 22B, to fit in, and the convex portions of the hook-shaped support pieces 22A and 22B are hooked onto the edges of the mounting groove 32 to accommodate the lower part of the support body 20, the excitation coil 14, and the detection coil 16 within the groove. If necessary, the mounting direction of the support body 20 can be aligned by checking the orientation of the support pieces 22A and 22B, which have different protruding lengths.

[0031] (Silicone resin fixing process) The lead wires of the excitation coil 14 and detection coil 16 are soldered to terminals (not shown) of the substrate 30. After checking the operation of the sensor, the alignment of the support 20 and the magnetic core 12 is checked, i.e., whether the magnetic core 12 protrudes from the support 20, and whether the excitation coil 14 and detection coil 16 are in contact with the abutment portion 24. After checking the alignment in this way, silicone resin 34 is applied to predetermined locations on the support 20 and fixed in place (see Figure 4(4)).

[0032] According to the manufacturing method of the parallel fluxgate sensor of the present invention, the coil to be inserted into the support can be easily aligned by simply butting it against the butting portion. Furthermore, when mounting the support on the board, alignment can be easily achieved by simply hooking the support piece protruding from the main body of the support. Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications can be made without departing from the spirit and scope of the present invention. Furthermore, the present invention is not limited to the combinations shown in the embodiments, but can be implemented in various combinations. [Explanation of symbols]

[0033] 10 parallel fluxgate sensors 12 magnetic core 14 Excitation coil 16 detection coil 17 Drive power supply 18 detectors 20 Support 22,22A,22B Support piece 24 Stopping part 30 boards 32 Mounting groove 34 Silicone Resin 40 recess

Claims

1. In a parallel fluxgate sensor, two linear magnetic cores made of a film or wire-shaped magnetic metal are arranged in parallel, and an excitation coil and a detection coil are provided on each of the magnetic cores, The magnetic core is sandwiched between supports made of a non-magnetic material having a size that suppresses deflection or vibration, and the excitation coil and the detection coil are simply inserted from both ends of the supports, 1. A parallel fluxgate sensor, comprising: an end portion of the support member provided with a support piece for engaging with an edge of a mounting groove of a sensor component;

2. 2. The parallel fluxgate sensor of claim 1, A parallel fluxgate sensor characterized in that the magnetic core is sandwiched between the supports having equal or larger sizes in at least part of its length and width.

3. 3. A parallel fluxgate sensor according to claim 1 or claim 2, A parallel fluxgate sensor characterized in that the thickness of the support is three times or more greater than the thickness of the magnetic core.

4. 4. A parallel fluxgate sensor according to claim 1, wherein: The parallel fluxgate sensor is characterized in that the support member has a butting portion that protrudes in the width direction to align the excitation coil and the detection coil with their mounting positions.

5. 5. A parallel fluxgate sensor according to claim 1, 1. A parallel fluxgate sensor, wherein the excitation coil and the detection coil are wound in the same direction and with the same number of turns.

6. 6. A parallel fluxgate sensor according to claim 1, 1. A parallel fluxgate sensor, wherein the detection coils installed on the two magnetic cores are connected in parallel.

7. 6. A parallel fluxgate sensor according to claim 1, 1. A parallel fluxgate sensor, wherein the detection coils installed on the two magnetic cores are connected in series.

8. 8. A parallel fluxgate sensor according to any one of claims 1 to 7, 1. A parallel fluxgate sensor, characterized in that the excitation coil and the detection coil installed on the magnetic core are installed at a distance of 1 / 10 or less of the total length of the magnetic core.

9. 9. A parallel fluxgate sensor according to any one of claims 1 to 8, A parallel fluxgate sensor characterized in that the excitation coil and the detection coil are installed within a range of 70% or less of the distance from the longitudinal center of the magnetic core to the end of the magnetic core.

10. a clamping step of inserting and clamping the magnetic core between supports; a coil mounting step in which an excitation coil and a detection coil are inserted from both ends of the support and moved until they abut against the abutting portion in the center; a mounting step of hooking the support piece of the support onto an edge of the mounting groove of the sensor component and storing the lower part of the support in the mounting groove; A method for manufacturing a parallel fluxgate sensor, comprising:

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