JPH11101658A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor, of which magnetic detection element and magnets can precisely be positioned in the case. SOLUTION: A magnetic detection element 22, a holding member 23 to hold the magnetic detection element 22, a magnet 24, a flexible copper laminated plate 25, and a resin holder 26 are built in a case 21. A holding piece 38 for magnetic detection element formed in the holding member 23 has elasticity and urges the magnetic detection element 22 toward the holding piece 37 for the magnetic detection element. The holding piece 37 for the magnetic detection element receives the magnetic detection element 22 and regulates the position of the magnetic detection element 22 to be constant. The magnet 24 is held by the holding member 23. The holding member 23 is joined to the case 21 at the tip end part 39a of the joining part 39. The flexible copper laminated plate 25 are turned along the surface of the holding member 23 and drawn out to the outside of the case 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor, for example, for detecting characters, symbols, patterns, and the like printed with magnetic ink, and for detecting the rotational speed by counting the teeth of a magnetic gear. It relates to the magnetic sensor used.

[0002]

2. Description of the Related Art An example of this type of magnetic sensor is shown in FIG. In the magnetic sensor 1, conductive films 4a and 4b and magnetoresistive element patterns 5a and 5b are formed in a resin layer 3 formed on a magnetic substrate 2 in a zigzag or meandering manner. A chip-shaped magnetoresistive element 7 in which the magnetoresistive element patterns 5a and 5b are covered with a protective film 6 is provided. The conductive films 4a and 4b have their end surfaces exposed from the protective film 6 and are electrically connected to external connection electrodes 8 and 9 formed on both end surfaces of the magnetoresistive element 7, respectively.

The magnetoresistive element 7 is arranged on a wiring board 11, and external connection electrodes 8 and 9 are connected to a circuit pattern 12 of the wiring board 11 by solder 13. Wiring board 11
Is fixed on one magnetic pole of the magnet 14. further,
The magnet 14 is fitted in a concave portion 15a formed in a support 15 made of an insulating resin material. This magnet 14
Apply a predetermined magnetic bias to the magnetoresistive element 7. The magnetoresistive element 7 and the magnet 14 are housed in a case 16 together with the support 15. The magnetoresistive element 7 is electrically connected to an external circuit via a terminal 17 soldered to a circuit pattern 12 of a wiring board 11 with solder 13.

The magnetic sensor 1 has a magnetoresistive element pattern 5
5, a and 5b are connected in series to a DC power supply 18, and outputs are obtained from both ends of the magnetoresistive element pattern 5b. Then, for example, when the magnetic ink on the detection target 19 passes over the magnetoresistive element pattern 5b and then passes over the magnetoresistive element pattern 5a as indicated by an arrow A, first, the resistance value of the magnetoresistive element pattern 5b Then, the resistance value of the magnetoresistive element pattern 5a increases. As a result, the two magnetoresistive element patterns 5a,
5b alternately changes, the output terminal T
An output voltage as shown in FIG. 6 is output between 1 and T2.

[0005]

The object to be detected 1
9 has a pattern drawn with magnetic ink and is read using the magnetic sensor 1, the width of the detection object 19 is generally wider than the width of the magnetoresistive element 7. The magnetoresistive element 7 only passes through a part of the design of the detection object 19. Therefore, the position of the magnetoresistive element 7 is
If the detected position is shifted from the normal position in the direction orthogonal to the moving direction A of the detected object 19, the magnetoresistive element 7 reads the position of the detected object 19 shifted from the normal reading position. Therefore, the output waveform of the magnetic sensor 1 is also different from the regular output waveform, and the collation does not match.

In the conventional magnetic sensor 1, the magnetoresistive element 7
Was simply fixed by soldering without being particularly positioned on the wiring board 11, so that the positional accuracy of the magnetoresistive element 7 was relatively low. Accordingly, the position of the magnetoresistive element 7 in the case 16 may be shifted in a direction orthogonal to the moving direction A of the detection object 19, and a magnetic sensor capable of outputting a regular output waveform is stably manufactured. There was a problem that you can not.

Further, in the conventional magnetic sensor 1, the magnet 14 for magnetic bias is also provided in the concave portion 1 formed in the support 15.
Since it is merely fitted without being particularly positioned on 5a, it is likely to be misaligned,
There is a problem that the magnetic sensor 1 having a constant output cannot be manufactured stably.

Accordingly, an object of the present invention is to provide a magnetic sensor capable of accurately positioning a magnetic detection element and a magnet in a case.

[0009]

In order to achieve the above object, a magnetic sensor according to the present invention comprises a magnetic detecting element and a holding member in which a magnet for applying a magnetic bias to the magnetic detecting element is made of a non-magnetic material. And the holding member is held in the case by a resin holder with a space between the case and the magnetic detection element, and the holding member elastically holds the magnetic detection element. Characterized in that the holding piece for a magnetic sensing element is provided.

According to the above configuration, since the magnetic sensing element is directly held by the magnetic sensing element holding piece, the position of the magnetic sensing element in the case is always constant with respect to the magnetic sensing element holding piece. In addition, the positioning accuracy of the magnetic detection element is improved.

Further, in the magnetic sensor according to the present invention, the holding member includes a magnet holding piece for holding the magnet.
The position of the magnet is always constant with reference to the magnet holding piece, and the magnet is assembled while always maintaining a constant positional relationship with the magnetic detection element.

Further, in the magnetic sensor according to the present invention, the resin holder has an engaging projection which engages with an engaging window provided in the case, and further includes a joining portion where the holding member is joined to the case. Have. Thereby, when assembling the magnetic sensor, the engagement protrusion of the resin holder is engaged with the engagement window of the case, and the resin holder, the magnetic detection element and the magnet held by the resin holder are prevented from dropping from the case.

Further, the magnetic sensor according to the present invention is characterized in that a flexible circuit board is electrically connected to the magnetic detecting element, and the flexible circuit board is drawn out of the case along the holding member. With the configuration described above, the flexible copper-clad laminate is freely bent along the holding member, and electrically connects the magnetic detection element and the external circuit.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the magnetic sensor according to the present invention will be described below with reference to the accompanying drawings.

The magnetic sensor 20 shown in FIGS. 1 and 2 has a case 21 in which a magnetoresistive element 22, a holding member 23 for holding the magnetoresistive element 22, a magnet 24, a flexible copper-clad laminate 25, and a resin holder are provided. 26 is built in. The magnetoresistive element 22 is liable to cause troubles such as output fluctuation, noise mixing, and shortening of service life due to a rapid change in temperature, adhesion of magnetic dust, moisture, water, salt water, and the like. Is housed in the case 21 and hermetically sealed. The case 21 is made of beryllium copper, phosphor bronze having a thickness of about 80 μm,
It is made of a non-magnetic material such as brass, nickel silver, non-magnetic stainless steel, ceramic, etc., and its outer surface is hard chrome plated to obtain wear resistance.

An air gap d is provided between the surface of the magnetoresistive element 22 and the upper inner wall surface of the case 21. what if,
If the magnetoresistive element 22 is in contact with the case 21, when an impact force is applied to the case 21, the impact force is transmitted to the magnetoresistive element 22, and a piezo signal is output from the magnetoresistive element 22 to become noise. This is to prevent this. However, when the impact force on the case 21 is relatively small, a resin plate may be provided between the surface of the magnetoresistive element 22 and the upper inner wall surface of the case 21.

The magnetoresistive element 22 is formed of a conductive film 29a, 29b and InSb formed in a zigzag or meandering manner on a magnetic substrate 27 made of a magnetic material such as alumina or ferrite via a resin layer 28. The magnetoresistive element patterns 31a and 31b made of the semiconductor material described above are formed. A protective film 32 is formed on the conductive films 29a and 29b and the magnetoresistive element patterns 31a and 31b.
The conductive films 29a and 29b have their end surfaces exposed from the protective film 32 and are electrically connected to external connection electrodes 33a and 33b formed on both end surfaces of the magnetoresistive element 22, respectively. The magnetoresistive element 22 is held on a holding member 23.

The holding member 23 is made of a non-magnetic metal material. As shown in FIG. 3, a base 36 for connecting two magnet holding pieces 34 and 35 extending in the same direction at one end thereof.
In addition, two magnetoresistive element holding pieces 37 and 38 which sandwich the magnetoresistive element 22 are provided. These two magnetoresistive element holding pieces 37, 38 project in the opposite direction to the magnet holding pieces 34, 35. Magnetoresistive element holding piece 37
Is a flat plate shape, and is used as a reference for positioning the magnetoresistive element 22. The magnetoresistive element holding piece 38 has a curved shape so as to have elasticity, and is disposed in parallel with and facing the magnetoresistive element holding piece 37. The holding surfaces of the holding pieces 37 and 38 for the magnetoresistive element are set parallel to the moving direction A of the detection target.

As shown in FIG. 2, the magnetoresistive element 22
The side surfaces on which the external connection electrodes 33a and 33b are not formed are sandwiched between the magnetoresistive element holding pieces 37 and 38. Since the holding piece 38 is curved to have elasticity, the magnetoresistive element 22 is urged by the holding piece 37. The holding piece 37 receives the magnetoresistive element 22, and always defines the position of the magnetoresistive element 22 on the holding member 23 in a direction perpendicular to the moving direction A of the detection target (hereinafter, referred to as a B direction) at a fixed position. can do.

As shown in FIG. 3, a ground terminal 35a of the magnetic sensor 20 is formed at the tip of the magnet holding piece 35. The earth terminal 35a has a connection hole 35b for facilitating connection with an external circuit.

Further, the holding member 23 has four joints 3 extending from the base 36 in the width direction of the magnet holding pieces 34 and 35.
9. Each of the joining portions 39 has a distal end portion 39a bent substantially at a right angle, abuts on the inner surface of the case 21, and is bonded or welded to the case 21 as shown in FIG.

The magnet 24 is made of a rare-earth magnetic material such as SmCo. The magnet 24 has a surface having polarity opposite to the base 36 of the holding member 23, and the magnet holding pieces 34 and 35 of the holding member 23 are described later. And is fixed by a resin 42 into a concave portion 41 formed by the resin holder 26. The magnet 24 applies a predetermined magnetic bias to the magnetoresistive element 22.

The flexible copper-clad laminate 25 is formed by covering four conductor patterns 25a made of copper foil or the like with a protective film 25b made of polyimide resin or the like. One end of the flexible copper-clad laminate 25 is connected to the base 36 of the holding member 23.
The protective film 25b is removed at a portion where the magnetoresistive element 22 is placed on the upper surface, the conductive pattern 25a is exposed, and the conductive pattern 25a is soldered to the external connection electrodes 33a and 33b of the magnetoresistive element 22 by the solder 30. I have. The flexible copper-clad laminate 25 is bonded and fixed to the holding member 23 with a resin.

The holding member 23 and the flexible copper-clad laminate 25 are insert-molded when the resin holder 26 is formed. The resin holder 26 is made of a thermoplastic resin such as polyphenylene sulfide (PPS).
The resin holder 26 has engagement projections 26a at positions corresponding to the two engagement windows 21a formed in the case 21 to prevent the resin holder 26 from falling off by engaging with the engagement windows 21a. Projecting.

In the magnetic sensor 20 having the above structure, as shown in FIG. 1, for example, the magnetic ink on the object to be detected moves in the direction indicated by the arrow A, and the magnetic resistance element pattern 31b
When passing above, the bias magnetic field of the magnet 24 concentrates on the magnetoresistive element pattern 31b, so that the resistance value of the magnetoresistive element pattern 31b increases. At this time, the resistance value of the magnetoresistive element pattern 31a does not change. Further, when the magnetic ink on the detection target moves in the direction of arrow A and passes over the magnetoresistive element pattern 31a, the resistance value of the magnetoresistive element pattern 31b drops to the original resistance value, and the resistance of the magnetoresistive element pattern 31a is reduced. The value increases. Accordingly, the resistance of each of the magnetoresistive element patterns 31a and 31b alternately changes, so that the magnetic sensor 20 outputs an output voltage similar to the output voltage shown in FIG.

As described above, since the magnetoresistive element 22 is directly held by the magnetoresistive element holding pieces 37 and 38 of the holding member 23, the magnetoresistive element 22
Is always constant with reference to the magnetoresistive element holding pieces 37 and 38, and the positioning accuracy of the magnetoresistive element 22 can be improved. The magnet 24 is also held between the magnet holding pieces 34 and 35, and the magnet 24 is always held at a fixed position with respect to the magnetoresistive element 22. further,
The holding member 23 is insert-molded in the resin holder 26, and the tip 39 a of the joint 39 is
Since it is joined to the inner surface, the holding member 23 is always fixed at a fixed position with respect to the case 21, and electrical shielding can be easily performed. Thus, the magnetic sensor 20 having the structure shown in FIGS. 1 and 2 can always obtain a stable output. Further, the flexible copper-clad laminate 25 can be bent freely and pulled out of the case 21. Therefore, the flexible copper-clad laminate 25 easily electrically connects the magnetoresistive element 22 to a circuit outside the case 21 without being substantially restricted by components such as the holding member 23 existing inside the case 21. can do.

The magnetic sensor according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the invention. For example, in the above-described embodiment, a magneto-resistive element has been described as an example of the magnetic detecting element, but a Hall element may be used as the magnetic detecting element.

[0028]

As is apparent from the above description, according to the present invention, the magnetic sensing element holding piece elastically sandwiches and holds the side surface of the magnetic sensing element, so that the magnetic sensing element is always in the magnetic sensing element. The magnetic sensor is held at a fixed position with respect to the holding piece, so that the same reading waveform is always obtained, and a magnetic sensor with little reading error and high detection accuracy can be obtained.

Further, since the magnet for the magnetic bias is fitted into the recess formed by the magnet holding piece and the resin holder, the position of the magnet with respect to the magnetic detecting element is also fixed, so that a stable output is obtained. Can be obtained.

Further, if the engagement projection of the resin holder is engaged with the engagement window provided on the case, the resin holder is prevented from dropping off the case when assembling the magnetic sensor. Assembling is facilitated, and assembling efficiency of the magnetic sensor is improved. In addition, by joining the joint of the holding member to the case, the holding member is fixed to the case and electrical shielding can be easily performed.

Furthermore, if the flexible copper-clad laminate is routed along the surface of the holding member, not only can insert molding of the flexible copper-clad laminate into the resin holder be easily performed, but also the flexible copper-clad laminate can be formed. Due to the flexibility, it can be easily pulled out of the case without being restricted by components such as holding members inside the case.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a magnetic sensor according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a perspective view of a holding member shown in FIG. 1;

FIG. 4 is a sectional view showing an example of a conventional magnetic sensor.

5 is a circuit diagram for explaining the operation of the magnetic sensor shown in FIG.

FIG. 6 is an explanatory diagram of an output waveform of the circuit shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 ... Magnetic sensor 21 ... Case 21a ... Engagement window 22 ... Magnetic resistance element 23 ... Holding member 24 ... Magnet 25 ... Flexible copper clad laminated board 26 ... Resin holder 26a ... Engagement protrusion 34, 35 ... Magnet holding piece 36 ... Bases 37, 38: holding piece for magnetoresistive element 39: joint

Claims (4)

[Claims] 1. A magnetic detecting element and a magnet for applying a magnetic bias to the magnetic detecting element are held by a holding member made of a non-magnetic material, and the holding member is connected to the case and the magnetic detecting element in a case. A magnetic sensor, wherein the magnetic sensor is held by a resin holder with an interval therebetween, and the holding member includes a magnetic detecting element holding piece for elastically holding the magnetic detecting element. 2. The magnetic sensor according to claim 1, wherein the holding member includes a magnet holding piece for holding the magnet. 3. The method according to claim 2, wherein the resin holder has an engagement protrusion that engages with an engagement window provided in the case, and the holding member has a joint that is joined to the case. The magnetic sensor according to claim 1 or 2, wherein: 4. A flexible circuit board is electrically connected to the magnetic sensing element, and the flexible circuit board is drawn out of the case along the holding member. Or the magnetic sensor according to claim 3.