JP2006058028A - Magnetic sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic sensor capable of easily correcting the dispersion of output voltage at a low cost, by making the distance between the magnet and the magnetoresistive element adjustable, using a simple constitution. <P>SOLUTION: In the depression parts 2a, 2b of the holder 3 the magnets 1a, 1b are accommodated, and on the substrate 4 fixed on the upper surface of the holder, the magnetoresistive elements 5a, 5b are mounted. By a plurality of protruded thread 6 provide in the depression part, the magnets 1a, 1b are held slidably toward the magnetoresistive elements 5a, 5b. At the bottom of the holder 3, an operation hole 7 is provided for sliding the magnets 1a, 1b toward the magnetoresistive elements 5a, 5b. By pushing the magnets toward the magnetoresistive elements via the operation hole, the distances 8 between the magnetoresistive elements and the magnets are adjusted. After adjustment, resin 9 is injected into the depression 2a, 2b from the operation hole 7 for fixing the magnets 1a, 1b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement in a magnetic sensor using a magnetoresistive element used as a rotation sensor, an angle sensor, a magnetic identification sensor, a proximity sensor, and the like, and its mounting structure.

Conventionally, as this kind of magnetic sensor, one having a structure in which a magnetoresistive element and a magnet arranged close to the magnetoresistive element are fixed to a housing or the like is generally known (for example, Patent Documents 1 and 2). reference).
The magnetoresistive element detects a change in the magnetic field applied to the magnetosensitive part (surface part) and outputs it as a signal, but its output signal voltage is weak and difficult to handle as it is. Therefore, the magnet arranged below it applies a bias magnetic field to the magnetoresistive element to move the magnetic operating point so that the output voltage level can be increased with respect to a minute change in magnetic field.

However, in the conventional magnetic sensor, if the resistance value of the magnetoresistive element, the magnetic flux density of the magnet, and the mounting position of the magnetoresistive element and the magnet vary, the output voltage is small or the output voltage varies. There was a problem.
In order to solve such a problem, in Patent Document 1, the above-described variation can be corrected by adjusting the distance between the magnetoelectric transducer and the magnet. In Patent Document 2, a magnetic material is provided under the magnet to change the intensity of the bias magnetic field applied to the magnetoresistive element, thereby adjusting the resistance value and sensitivity of the magnetic sensor.

Japanese Patent Laid-Open No. 9-257897 JP 2000-39472 A

However, in the magnetic sensor of Patent Document 1, a screw portion is provided on the inner surface of the magnet housing portion, and a screw portion that is screwed to the rotating plate on which the magnet is placed is provided. However, there is a problem that the manufacturing cost is high because the structure is complicated.
In addition to the magnetoresistive element and the magnet, the magnetic sensor disclosed in Patent Document 2 requires a magnetic material, and the magnetic material must be appropriately selected according to the required output voltage, resulting in high cost. There was a problem of becoming.

  The present invention has been made in view of such conventional circumstances, and the object of the present invention is to make it possible to adjust the gap between the magnet and the magnetoresistive element with a simple configuration so that the output voltage can be easily varied. It is to provide a magnetic sensor that can be corrected at low cost.

In order to achieve the above object, a magnetic sensor according to the present invention is housed in a fitting manner in a holder (3) having recesses (2a, 2b) for receiving magnets (1a, 1b) and the recesses. A magnetic sensor (a) comprising a magnet, a substrate (4) fixed on the upper surface of the holder, and a magnetoresistive element (5a, 5b) mounted on the substrate and fixed in proximity to the magnet. There,
In the recess, provided is a holding means (6) for slidably holding the magnet toward the magnetoresistive element,
On the bottom surface of the holder, an operation hole (7) is provided for sliding the magnet accommodated in the recess toward the magnetoresistive element,
The distance (8) between the magnetoresistive element and the magnet is adjusted by pushing the magnet toward the magnetoresistive element through the operation hole.

  In such a configuration, the distance (8) between the magnetoresistive elements (5a, 5b) and the magnets (1a, 1b) is a simple structure in which the operation hole (7) is simply provided on the bottom surface of the holder (3). The output voltage variation can be corrected by adjusting.

  After adjusting the variation of the output voltage in this way, it is preferable to fix the magnets (1a, 1b) by injecting resin into the recesses (2a, 2b). In this case, in order to inject the resin from the bottom surface side of the holder (3), the magnetoresistive elements (5a, 5b) are in the way, so that the operation hole (7) provided on the bottom surface of the holder (3) is used. It is preferable to inject resin into the recesses (2a, 2b).

Further, the holding means may be a means in which the magnets (1a, 1b) fit slightly loosely in the recesses (2a, 2b), but in that case, a resin filling for fixing the magnets in the recesses Since the gap for this purpose is ensured only on the bottom surface side of the recess, there is a possibility that the fixing of the magnet with the injected resin may become unstable.
Therefore, the holding means is composed of convex portions (6) projecting at a plurality of locations on the inner side surface of the concave portion, and the convex portions provide a gap between the magnet accommodated in the concave portion and the inner side surface of the concave portion. And a gap (10) filled with the resin is formed,
It is preferable that the plurality of convex portions (6) are evenly arranged in the concave portions (2a, 2b) so that the magnets (1a, 1b) are not unevenly distributed in the concave portions.
In this case, since the gap for resin filling for fixing the magnet in the recess is ensured on the bottom surface side and the side surface side of the recess, the magnet is more reliably fixed by the injected resin. In addition, since the gaps for filling the resin are evenly formed between the inner side surface of the recess and the outer side surface of the magnet, the centering of the magnets (1a, 1b) is more reliably performed, and the output due to the deviation of the magnet installation position Voltage variations can be prevented as much as possible.

By the way, when this kind of magnetic sensor is used, for example, to detect the rotation speed, rotation direction, etc. of a gear of a machine tool, the magnetic sensor a is accommodated in a case b as shown in FIGS. The case b is fixed to the sensor mounting surface 100 with a screw 25 or the like.
At this time, there is a possibility that the output waveform from the magnetic sensor a is shifted due to the positional deviation of the magnetoresistive elements 5a and 5b.
Therefore, the magnetic sensor (a) is attached to the case (b) so as to be rotatable within a predetermined range, and the phase shift in the output waveform from the magnetoresistive elements (5a, 5b) (A / B of the magnetoresistive element) It is preferable to be able to correct the phase shift between the output waveform from the phase and the output waveform from the Z / Z-phase.
In this case, it is possible to easily correct the deviation of the output waveform due to the positional deviation of the magnetoresistive elements (5a, 5b) only by rotating the magnetic sensor (a). Further, by restricting the rotation range of the magnetic sensor (a) within a predetermined range, it is possible to prevent excessive rotation when the magnetic sensor (a) is rotated.

In addition, a metal screw (27) is housed in a fixing screw insertion hole (26) for fixing the case (b) to the sensor mounting surface (100), and one end of the sleeve is attached to the sensor mounting surface ( 100) projecting toward the side of the sensor mounting surface (100) and the bottom surface of the case (b), vibrations from the sensor mounting surface (100) (vibration due to gear rotation, machine tool vibration, etc.) It is preferable that the gap (28) for preventing transmission is secured.
In this case, erroneous detection of the magnetic sensor due to the influence of vibration from the sensor mounting surface can be prevented, and highly accurate detection can be performed.

  Since the magnetic sensor of the present invention is configured as described above, it is possible to accurately set and correct output voltage variations and phase shifts with a simple configuration. Therefore, for example, it is possible to provide a magnetic sensor used for detecting the rotation speed, rotation direction, and the like of the gear of the machine tool at a low cost.

  Embodiments of the present invention will be described below with reference to the drawings.

1A is a perspective view of the magnetic sensor a of this example, FIG. 1B is an exploded perspective view thereof, and the magnetic sensor a includes magnets 1a and 1b, a holder 3, a substrate 4, a magnetoresistive element 5a, 5b.
2B is an enlarged cross-sectional view of a main part in a state where the magnetic sensor a is mounted on the case b, and FIG.

  The holder 3 has left and right recesses 2a and 2b for accommodating the magnets recessed from the upper surface side toward the bottom surface side, and a plurality of protrusions 6 provided on the inner side surfaces of the respective recesses 2a and 2b 1a and 1b are held in the respective recesses 2a and 2b in a fitting manner so that they can slide toward the magnetoresistive elements 5a and 5b.

  As shown in FIG. 2 (a), the respective protrusions 6 are evenly arranged on the inner surfaces of the recesses 2a and 2b so that the magnets 1a and 1b are not unevenly distributed in the recesses 2a and 2b. As shown in FIG. 2 (b), the upper end portion of each protrusion 6 is formed as a tapered portion 6a so that the magnets 1a and 1b can be easily inserted into the recesses 2a and 2b from the upper surface side of the holder 3. Has been. Also, a resin 9 for fixing a magnet (in the illustrated example, the resin is omitted) between the magnets 1a, 1b accommodated in the recesses 2a, 2b and the inner surfaces of the recesses 2a, 2b by the respective protrusions 6. A gap 10 is formed to be filled.

On the upper surface of the holder 3, the left and right magnetoresistive elements 5a and 5b are mounted, and a substrate 4 provided with output wirings 11 and output pins 12 connected to the respective magnetoresistive elements 5a and 5b is fixed.
The fixing means for the holder 3 of the substrate 4 may be bonding, welding, screwing, or the like. However, according to such fixing means, there is a possibility that displacement of the magnetoresistive elements 5a, 5b with respect to the magnets 1a, 1b may occur. is there. Therefore, in this example, either one of the holder 3 and the substrate 4 is provided with a boss 13a, and the other is provided with a boss hole 13b so that the magnetoresistive elements 5a and 5b are accurately positioned with respect to the magnets 1a and 1b. ing. Further, the fixing pin 14 penetrating the holder 3 and the substrate 4 is fixed to the holder 3 or the substrate 4 by soldering 15 or caulking so that the substrate 4 is fixed in close contact with the holder 3 so that the magnet 1a is fixed. , 1b and the magnetoresistive elements 5a, 5b are prevented from forming an excessive gap.

  On the bottom surfaces of the recesses 2a and 2b, the magnets 1a and 1b accommodated in the recesses 2a and 2b slide toward the magnetoresistive elements 5a and 5b on the substrate 4 as shown in FIG. An operation hole 7 is formed for this purpose. Then, after fixing the substrate 4 on which the magnetoresistive elements 5a and 5b are mounted on the upper surface of the holder 3 in which the magnets 1a and 1b are accommodated in the recesses 2a and 2b, the magnets 1a and 1b are attached via the operation holes 7. By pushing toward the magnetoresistive elements 5a and 5b, the interval 8 between the magnetoresistive elements 5a and 5b and the magnets 1a and 1b is finely adjusted, and the output from the magnetoresistive elements 5a and 5b due to the size of the interval 8 The voltage variation can be adjusted. In the illustrated example, a state in which the interval 8 between the magnetoresistive elements 5a and 5b and the magnets 1a and 1b is eliminated is shown.

Further, the operation hole 7 is a resin 9 for fixing the magnets 1a, 1b in the recesses 2a, 2b after adjusting the distance 8 between the magnetoresistive elements 5a, 5b and the magnets 1a, 1b as described above. Also serves as an injection hole for injecting.
The resin 9 injected from the operation hole 7 flows into the gap 10 formed uniformly between the outer surface of the magnets 1a and 1b and the inner surface of the recesses 2a and 2b by the above-described protrusions 6, and the magnet 1a and 1b are fixed to the centers of the recesses 2a and 2b.

  In the magnetic sensor a of this example having such a configuration, a jig or the like is inserted into the operation hole 7 to finely adjust the interval 8 between the magnetoresistive elements 5a and 5b and the magnets 1a and 1b. The resulting variation in output voltage can be easily corrected.

Next, the case where the magnetic sensor a of this example is used as a detection sensor for the rotational speed and rotational direction of a gear such as a machine tool will be described with reference to FIGS.
FIG. 3 is an explanatory view of the magnetoresistive element, FIG. 4 is an explanatory view when the mounting displacement of the magnetoresistive element occurs, FIG. 5 is a simplified cross-sectional view of the state in which the magnetic sensor a is attached to the base 100 by the case b, 7 is an explanatory diagram of the case b, FIG. 7 is an explanatory diagram of a modification of the case b, and FIG. 8 is a use state diagram when the rotational speed and direction of the gear 200 such as a machine tool are detected by the magnetic sensor a.

The magnetic sensor a of this example includes a magnetoresistive element 5a that outputs a Z / Z-phase for detecting the rotation speed of the gear 200 and an A / B phase output for detecting the rotation direction of the gear 200. The magnetoresistive element 5b to be performed is provided, and two magnets 1a and 1b and two concave portions 2a and 2b are provided correspondingly. The detailed arrangement of the magnetoresistive elements MR1 to MR8 constituting the magnetoresistive elements 5a and 5b is shown in FIG. 3B, the configuration diagram of the internal circuit is shown in FIG. 3C, and the Z / Z− phase and the A / A The output waveform of the B phase is shown in FIG.
As shown in FIG. 3 (d), if there is no displacement of the magnetoresistive elements 5a and 5b in the magnetic sensor a, that is, if the magnetoresistive elements 5a and 5b are not displaced relative to the magnets 1a and 1b, the Z / Z-phase The output waveform from the magnetoresistive element 5a and the output waveform from the A / B phase magnetoresistive element 5b are in an ideal state.

  However, in actuality, as shown in FIG. 4 (a), when mounting each of the magnetoresistive elements 5a and 5b on the substrate 4, there is a possibility that a slight misalignment of each of the magnetoresistive elements 5a and 5b may occur. Yes, in this case, as shown in FIG. 4B, the phase shift between the output waveform from the Z / Z-phase magnetoresistive element 5a and the output waveform from the A / B phase magnetoresistive element 5b. Occurs.

  Therefore, in this example, the magnetic sensor a is mounted so as to be rotatable within a predetermined range with respect to the case b, and the output waveform of each of the magnetoresistive elements 5a and 5b due to the mounting misalignment of the magnetoresistive elements 5a and 5b. The phase shift can be corrected.

  The case b is integrally formed of a desired synthetic resin, and includes a box-shaped housing portion 20 for housing the magnetic sensor a and a disk-shaped mounting portion 21 for fixing the case b to the pedestal 100. The magnetic sensor a is mounted in a circular mounting hole 23 provided in the front wall 22 of the housing portion 20 so that it can rotate only within a predetermined range.

  That is, as shown in FIGS. 6A, 6B, etc., the outer peripheral edges 31a and 31b of the magnetic sensor a before and after the holder 3 are in sliding contact with the mounting hole 23 so that the magnetic sensor a can be freely rotated. It is formed in the shape of an arc fixed to 23. Further, a notch 32 is formed at the center of the outer peripheral edge 31a on the Z / Z-phase magnetoresistive element 5a side so that a pin 24 protruding from the inner peripheral upper side of the mounting hole 23 is loosely inserted. When attaching the magnetic sensor a to the case b, the magnetoresistive element 5a for Z / Z-phase is always positioned on the upper side, and the rotation range of the magnetic sensor a is limited to a predetermined range (notched by the pin 24). Only 32 opening ranges).

  In this way, as shown in FIG. 6C, the magnetic sensor a mounted on the case b is rotated to correct the mounting misalignment of the magnetoresistive elements 5a and 5b, and shown in FIG. The phase shift between the output waveforms of the Z / Z− phase and the A / B phase can be matched as shown in FIG. 3D or the phase shift can be made as small as possible.

  Also, as shown in FIG. 6 (d), a plurality of protrusions 33 are arranged so that the protrusions 33 protruding about 1 mm or less in sliding contact with the inner periphery of the mounting hole 23 are evenly arranged on the front and rear outer peripheral edges 31a and 31b of the holder 3. By providing the center of the magnetic sensor a with respect to the mounting hole 23, it is possible to improve the prevention of variations in output voltage due to the positional deviation of the magnetic sensor a.

  An insertion hole 26 for a screw 25 for fixing the case b to the pedestal 100 is formed on the left and right sides of the mounting portion 21 of the case b. The screw insertion hole 26 is internally provided with a metal sleeve 27. In addition, the lower end portion of the sleeve 27 protrudes toward the base 100 side. This secures a gap 28 between the pedestal 100 and the bottom surface of the case b to prevent transmission of vibration from the pedestal 100, thereby preventing erroneous detection of the magnetic sensor a due to the influence of vibration from the pedestal 100. Thus, highly accurate detection can be performed.

The case b in FIG. 7 includes a convex portion 29 that is integrally projected at a location corresponding to the left and right insertion holes 26 in the bottom wall of the housing portion 20, and the convex portion 29 and the left and right sleeves 27, the case b is supported at three points to prevent rattling of the case b.
If the projecting dimension of the convex portion 29 is set to be higher than the projecting dimensions of the left and right sleeves 27, the bottom wall of the case b is elastically deformed when the screws 25 are tightened, and the case b is deformed. It is possible to improve the prevention of rattling.

  As described above, the embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to the illustrated examples. For example, one magnetoresistive element is used to detect only the A / B phase. Only a single magnet or the like, or changing the external shape of the magnetic sensor a or the case b, and various other methods within the scope of the technical idea described in the claims. It goes without saying that changes are possible.

(A) A perspective view showing an example of a magnetic sensor according to the present invention, (b) an exploded perspective view of the same. (A) The principal part enlarged plan view of the holder of the magnetic sensor shown in FIG. 1, (B) The longitudinal cross-sectional view in the case mounting state of the magnetic sensor shown in FIG. (A) Plan view of magnetoresistive element, (b) Arrangement of magnetoresistive element, (c) Internal circuit diagram of magnetoresistive element, (d) Output waveform diagram of magnetoresistive element. (A) A plan view showing a mounting deviation state of the magnetoresistive element, and (b) a waveform diagram showing a phase deviation of the output waveform of the magnetoresistive element. Sectional drawing which shows an example of the attachment structure of the magnetic sensor which concerns on this invention. (B) Front view of rear side of case shown in FIG. 5, (b) Enlarged view of the main part, (c) Schematic diagram showing rotation state of magnetic sensor, (d) Magnetic sensor mounting hole according to other embodiment Enlarged view of. (A) A cross-sectional view showing another example of the magnetic sensor mounting structure according to the present invention, (b) a perspective view of the bottom side of the case. The side view which shows an example of the use condition of the magnetic sensor which concerns on this invention.

Explanation of symbols

a: Magnetic sensor 1a, 1b: Magnet 2a, 2b: Concave part 3: Holder 4: Substrate 5a, 5b: Magnetoresistive element 6: Projection (convex part as magnet holding means)
7: Operation hole 8: Spacing between magnet and magnetoresistive element 9: Injection resin 10: Clearance for filling resin b: Case 25: Screw 26: Screw insertion hole 27: Sleeve 28: Clearance 100: Base (sensor mounting surface)

Claims (5)

A holder (3) having recesses (2a, 2b) for receiving magnets (1a, 1b), a magnet housed in the recesses in a fitting manner, and a substrate (4) fixed to the upper surface of the holder; A magnetoresistive element (5a, 5b) mounted on the substrate and fixed in proximity to the magnet,
In the recess, provided is a holding means (6) for slidably holding the magnet toward the magnetoresistive element,
On the bottom surface of the holder, an operation hole (7) is provided for sliding the magnet accommodated in the recess toward the magnetoresistive element,
The magnetic sensor, wherein the distance (8) between the magnetoresistive element and the magnet is adjusted by pushing the magnet toward the magnetoresistive element through the operation hole.   The magnetic sensor according to claim 1, wherein the magnet is fixed to the holder by a resin (9) injected from the operation hole into the concave portion after adjusting a distance between the magnetoresistive element and the magnet. . The holding means comprises convex portions (6) projecting at a plurality of locations on the inner side surface of the concave portion, and the convex portions allow the magnet accommodated in the concave portion and the inner side surface of the concave portion, A gap (10) filled with the resin is formed,
The said some convex part (6) is arrange | positioned equally in the said recessed part (2a, 2b) so that the said magnet (1a, 1b) may not be unevenly distributed in the said recessed part, The Claim 2 characterized by the above-mentioned. Magnetic sensor. A magnetic sensor (a) according to any one of claims 1 to 3, and a case (b) for fixing the magnetic sensor to the sensor mounting surface (100),
An attachment structure for a magnetic sensor, wherein the magnetic sensor is attached to the case so as to be rotatable within a predetermined range, and a phase shift in an output waveform from the magnetoresistive element can be corrected.   The case (b) has a fixed screw insertion hole (26) for fixing the case to the sensor mounting surface (100), and a metal sleeve (27) is provided in the screw insertion hole. One end of the sleeve protrudes toward the sensor mounting surface, and a gap (28) for preventing transmission of vibration from the sensor mounting surface is secured between the sensor mounting surface and the case. The magnetic sensor mounting structure according to claim 4, wherein:

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