JPH1130657A - Magnetometric sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make improvements in handleability in making a coil easily rollable around a magnetic line by winding this bias magnetic field impressing coil to a support board supporting this magnetic line. SOLUTION: This M1 element winds a bias magnetic field impressing coil 11 around a supporting board 12 supporting a magnetic line 10 in use of its notch 12a, whereby this coil 11 is made easily rollable around the magnetic line 10 and also so as to make the handleability better. In addition, a magnetic line mounting pin 16 through which the magnetic line 10 is temporarily lockable to the supporting board, is used and this mounting pin 16 is soldered to a soldering land on the supporting board 12, and thus mounting strength of the magnetic line 10 and conductive reliability are made so as to be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic impedance effect element and a magnetic inductance element suitable for use in a magnetic head of an AV device, a control device, a computer, etc., or a compass, etc. And the like.

[0002]

2. Description of the Related Art Recently, there has been an increasing demand for downsizing and high sensitivity of a magnetic sensor. Attempts to use a magnetoresistive element (MR element) for detecting a magnetic flux itself instead of a temporal change of the magnetic flux as a head have been actively made. It is being studied. Such an MR element utilizes a phenomenon in which the electrical resistance due to the interaction between the magnetization of a ferromagnetic material and the conduction electrons of a direct current is changed by an external magnetic field, and is effective in promoting miniaturization. However, since the MR element has a very small rate of change in electrical resistance, the signal-to-noise ratio (S / N ratio)
Is not sufficient, and it is difficult to obtain a desired detection sensitivity.

Recently, research on a giant magnetoresistive element (GMR element) for detecting a change in an external magnetic field by utilizing a phenomenon called a giant magnetoresistance effect has been widespread. Since the rate of change in resistance is not sufficient, and there is a problem of hysteresis, this technique is not suitable for promoting miniaturization.

Therefore, as a high-sensitivity micro magnetic sensor element capable of solving such problems of the MR element and the GMR element, a magnetic impedance effect element (hereinafter, referred to as Japanese Patent Application Laid-Open No. 7-181239) is disclosed. MI device) has been proposed. Such an MI element utilizes an electromagnetic phenomenon that when a high-frequency current is applied to a magnetic wire made of a high-permeability magnetic material, an impedance due to a skin effect is greatly changed by an external magnetic field. When an amorphous wire having a diameter of about 30 μm is used, an impedance change of 50% or more can be obtained with a magnetic field of several gauss, so that it is possible to provide a small and highly sensitive magnetic sensor.

[0005] FIG.
FIG. 4 is a characteristic diagram showing a correlation between a voltage generated between both ends of an amorphous magnetic wire and an external magnetic field when a sine wave high-frequency current of 0 kHz or more is applied, and shows both ends of the magnetic wire according to the magnitude of the external magnetic field. It can be seen that the voltage between them changes.
However, as shown in FIG. 20, the change in the voltage between both ends of the magnetic wire (the sensing portion contributing to the detection of the external magnetic field) is symmetrical with respect to the center when the external magnetic field is 0 Gauss. When the sensor is used as a sensor capable of detecting not only the size but also the direction, the operating point (the state where the external magnetic field is 0) is moved to an appropriate position where the linearity of the graph can be ensured, such as point A in FIG. (Coordinate point shown).

Therefore, in such a case, conventionally, FIG.
As shown in FIG. 1, a magnetic wire 2 is inserted into a tube 1 made of a nonmagnetic material such as vinyl, and a DC current is applied to a coil 3 wound around the outer circumferential surface of the tube 1 by a predetermined number of turns. To set the operating point. Both ends of the magnetic wire 2 are soldered to a conductive wire, a solder land, or the like, and the magnetic wire 2 between the pair of solder connection portions 4 and 4 serves as a sensing portion that contributes to detection of an external magnetic field. By measuring the voltage, the magnitude and direction of the external magnetic field can be detected.

[0007]

By the way, in the above-mentioned conventional MI element, the coil 3 for applying the bias magnetic field is wound around a tube 1 made of vinyl or the like. This tube 1 has an outer diameter of about 0.5 mm. Since the length is as small as about 1 to 3 mm, the assembling work of winding the coil 3 around the outer peripheral surface for several tens of turns or more is not easy, and it is difficult to say that the handling property is good.

In such a conventional MI element, electrical and mechanical connection is made by soldering the end of the magnetic wire 2 to a conductor or the like. Because of poor wettability, it was not possible to expect sufficient attachment strength and conduction reliability at the solder connection site 4 to which the end was soldered.

[0009]

According to the present invention, a coil for applying a bias magnetic field is wound around a support substrate for supporting a magnetic wire, so that the coil can be easily wound around the magnetic wire and has good handleability. In addition, by using a magnetic wire mounting member that can temporarily fix the magnetic wire to the support substrate, the mounting strength and conduction reliability of the magnetic wire are improved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a magnetic sensor according to the present invention, a magnetic wire made of a high-permeability magnetic material, the voltage of which is generated by applying a time-varying current, changes with an external magnetic field, And a coil wound around the magnetic wire for applying a bias magnetic field, and the coil is wound around the support substrate to form the wound state. Here, it is preferable that a pair of conductive portions (solder lands, etc.) are provided on the support substrate so as to be separated from each other, and both ends of the sensing portion of the magnetic wire are electrically connected to these conductive portions.
Further, in addition to the above configuration, a magnetic wire attaching member is provided which is attached to the support substrate in a state where the magnetic wire is held between the support substrate and the magnetic wire, and the magnetic wire attaching member is soldered to the conductive portion of the support substrate. It is preferable to do so. Note that, as the magnetic wire, an amorphous magnetic wire that can obtain high magnetic permeability is preferable.

As described above, when the coil is wound around the support substrate that supports the magnetic wire and the coil is wound, the assemblability and handling of the magnetic sensor are improved as compared with the case where the coil is wound around a tube such as vinyl. . Further, if the magnetic wire can be temporarily fixed to the support substrate and a magnetic wire mounting member having better solder wettability than the magnetic wire is used, by securely soldering the mounting member to the conductive portion of the support substrate, The mounting strength and conduction reliability of the magnetic wire can be greatly improved.

Further, a cover member for covering the magnetic wire is provided on the support substrate, and a coil is wound around the cover member and the support substrate, so that the axis of the coil is set to substantially coincide with the magnetic wire. It is preferable because a bias magnetic field substantially parallel (substantially coincident) with the extending direction (length direction) of the magnetic wire can be easily applied to the magnetic wire.

It is preferable that the support substrate or the cover member be provided with a positioning portion such as a notch for regulating the position of the coil and defining the winding range, since the assemblability is further improved.

[0014]

Embodiments will be described with reference to the drawings.
1 to 6 are views for explaining a first embodiment of the present invention. FIG. 1 is a perspective view of a support substrate used in the embodiment, and FIG. 2 is a perspective view of a mounting pin used in the embodiment. And front view,
3 is an explanatory view showing an assembling procedure of the embodiment, FIG. 4 is an explanatory view showing a state where the MI element (magnetic sensor) according to the embodiment is mounted on a circuit board, and FIG. 5 is an MI element in FIG. FIG. 6 is a partially cutaway perspective view showing a case where the MI element according to the embodiment is packaged by being sealed with an insulating resin.

In these figures, reference numeral 10 denotes a linear magnetic wire made of an amorphous wire which is a high magnetic permeability magnetic material, 11 denotes a coil for applying a bias magnetic field to the magnetic wire 10, and 12 denotes a magnetic wire 10 or A rigid support substrate for supporting the coil 11, a pair of solder lands 13 provided on the support substrate 12 for soldering both ends of the magnetic wire 10, and a pair of solder lands 14 similarly provided on the support substrate 12 Solder lands to which both ends of the coil 11 are soldered outside 13, solder 15, a pair of magnetic wire attaching pins 16 which hold both ends of the magnetic wire 10 and are inserted into the support substrate 12, 17 is A pair of coil mounting pins that hold both ends of the coil 11 and are inserted into the support board 12, 18 is a circuit board which is a mother board (main board) on which the support board 12 is mounted, and 19 is insulating MI element inside a resin indicates a shaped body to be sealed.

More specifically, as the magnetic wire 10, Fe (4.35) Co (68.15) Si (12.
5) As-cast of almost zero magnetostriction of B (15) composition
An amorphous wire obtained by dicing the wire into a diameter of 30 μm is used.
Tensile heat treatment is performed in which a tension of ² is applied and annealing is performed at 475 ° C. for 15 seconds. In addition, this magnetic wire 1
0, a sensing portion contributing to the detection of an external magnetic field (a solder portion stretched between a pair of magnetic wire mounting pins 16 and 16).
5; that is, a pair of solder lands 1
3) is 3 mm in length. The portion of the magnetic wire 10 extending outside the sensing portion, such as the portion buried in the solder 15, does not directly contribute to the detection of the external magnetic field, but the amorphous magnetic wire easily absorbs the magnetic flux. Solder 15 at both ends of wire 10
If it extends a little from the outside to outside, a magnetism collecting effect can be expected.

In the present embodiment, as the support substrate 12,
A glass-containing epoxy resin substrate having a length of about 14 mm, a width of about 4 mm, and a thickness of about 1 mm is used, and the solder lands 13 and 14 made of copper foil are connected to the support substrate 12 by a known technique such as etching. It is formed in the upper predetermined position. On both side edges of the support substrate 12, notches 12a having a length of 8 mm are provided as positioning portions for regulating the position of the coil 11 and defining a winding range. Solder land 1 inside from both ends in the direction
3 and the solder land 14 on the outside. Furthermore, the solder land 1 on the support substrate 12
3, a mounting hole 13a for a mounting pin 16 is provided.
Mounting hole 14a is provided. Note that the support substrate 12 may be formed of another non-magnetic insulating material, for example, phenol resin.

The mounting pins 16 and 17 are pins having a shape as shown in FIG. 2 and are much more solder-wet than magnetic wires such as gold-plated brass plated with nickel or phosphor bronze plated with copper solder. It is made of a good material. As shown in FIG. 2B, through holes 16b for inserting the ends of the magnetic wire 10 and the coil 11 are provided at the roots of the heads 16a and 17a of the mounting pins 16 and 17, respectively. 17b is perforated. As shown in FIG. 3, the magnetic wire mounting pin 16 is inserted so that the through hole 16b faces the longitudinal direction (longitudinal direction) of the support substrate 12, and the coil mounting pin 17 is supported by the through hole 17b. It is inserted so as to face the width direction (transverse direction) of the substrate 12.

The coil 11 is an enamel wire having a diameter of 100 μm and is wound around the magnetic wire 10 for, for example, 100 turns. However, as shown in FIGS. 3 to 5, the coil 11 is wound around a portion of the support substrate 12 sandwiched between a pair of notches 12 a, and the coil 11 is wound by these notches 12 a. The mounting range is specified. The enameled wire is formed, for example, by applying a polyurethane film to a copper wire.

When assembling the MI element using the above-described members, first, the ends of the magnetic wires 10 are inserted into the through holes 16b of the pair of magnetic wire mounting pins 16, respectively.
As shown in (a), these mounting pins 16 are inserted into mounting holes 13a in the solder lands 13 of the support substrate 12 and inserted. In this case, since both ends of the magnetic wire 10 can be sandwiched between the head 16a of each mounting pin 16 and the solder land 13 on the support substrate 12, the magnetic wire 10 can be temporarily fixed at a predetermined position.

Next, as shown in FIG. 3B, each mounting pin 16 is soldered to the corresponding solder land 13 by the solder 15 on the solder land 13. At this time, since the solder wettability is good, the mounting pin 16 is firmly soldered to the solder land 13. Therefore, the end of the magnetic wire 10 sandwiched between the mounting pin 16 and the solder land 13 is also soldered. 1
5 can be securely held in close contact.

Thereafter, using the notch 12a, the coil 11 is attached to the supporting substrate 12 by a predetermined number of turns (for example, 100 turns).
Turn) wrap. In other words, the coil 11 is wound from one end to the other end in the longitudinal direction of the notch 12a, and the coil 11 is wound around the magnetic wire 10. However, since the pair of magnetic wire mounting pins 16 soldered on each solder land 13 are located inside both ends in the longitudinal direction of the notch 12a, as shown in FIG.
Both ends of the winding portion of the coil 11 are located outside the respective mounting pins 16.

Thereafter, both ends of the coil 11 are inserted into the through holes 17b of the pair of coil mounting pins 17, respectively, and these mounting pins 17 are inserted into the mounting holes 14a in the solder lands 14 to be mounted on the support substrate 12. By doing so, both ends of the coil 11 are held between the head 17a of each mounting pin 17 and the corresponding solder land 14. Then, both ends of the coil 11 temporarily fixed in this way are soldered on the corresponding solder lands 14, thereby forming a single M as shown in FIG.
The I element is completed.

Although not shown, the magnetic wire 10 and the coil 11 of the MI element are coated with a resin such as epoxy made of an insulating and non-magnetic material and cured to prevent disconnection. is there.

In the MI element thus constructed, the coil 11 is wound around the support substrate 12 supporting the magnetic wire 10, so that the coil is wound around a tube of vinyl or the like. In addition, the winding operation of the coil 11 is facilitated, the assembling property is improved, and the handling property is also improved. In addition, the support substrate 12 includes the coil 1
Notch 12 for regulating the position of 1 and defining the winding range
Since a is provided, the assemblability and reliability when winding the coil 11 are further improved.

In the above-described MI element, the magnetic wire mounting pins 16 that can temporarily fix the ends of the magnetic wires 10 to the support substrate 12 during assembly can be securely soldered to the solder lands 13. Strength and conduction reliability are greatly improved. Moreover, since the coil mounting pins 17 for temporarily fixing the coil 11 and soldering to the solder lands 14 are mounted on the support substrate 12 outside the winding range, the magnetic wire mounting pins 16 and the coil mounting pins 16 are eventually mounted. 17 function as terminals, and the MI element has excellent handleability.

In the above-described MI element, the coil is disposed outside the sensing portion (the portion contributing to the detection of the external magnetic field) of the magnetic wire 10 stretched between the pair of magnetic wire mounting pins 16. 11 is designed so that both ends of the winding portion of the coil 11 are positioned, the bias magnetic field generated when a portion of the coil 11 wound around the magnetic wire 10 is energized is longer than the length of the magnetic wire 10. It is almost uniform over the entire width direction. That is, since the magnetic field generated by the coil 11 has a characteristic that it is substantially uniform except for both ends of the winding portion, an uneven bias magnetic field is generated by the magnetic wire 1.
In order to prevent a decrease in detection accuracy caused by being applied to zero, in the present embodiment, care is taken so that magnetic fields generated at both ends of the winding portion of the coil 11 do not adversely affect the sensing portion of the magnetic wire 10. It is. When the bias magnetic field is uniformed in the length direction of the magnetic wire 10 as described above, the graph showing the correlation between the voltage of the sensing portion of the magnetic wire 10 and the external magnetic field hardly changes its shape. Since the shift is performed by the amount corresponding to the bias magnetic field, the operating point can be set at a desired coordinate point at which the linearity of the graph can be ensured.

The above-described MI element can be mounted on a circuit board 18 as a sub-board (sub-board) as shown in FIGS. That is, the front ends 16c and 17c of the mounting pins 16 and 17 of the MI element are inserted into the terminal insertion holes 18a and 18b of the circuit board 18 on which electronic components (not shown) are mounted. By soldering from the side, each mounting pin 16, 17
Is mounted on the circuit board 18. As described above, since the MI element that can use the magnetic wire mounting pin 16 or the coil mounting pin 17 as a terminal does not require wire bonding when mounted on the circuit board 18, it is easy to assemble and contributes to improving the productivity of the magnetic sensor. . In addition, in the MI element, a direct current is applied to the coil 11 to generate a bias magnetic field.
The external magnetic field can be detected by applying a high-frequency current to the magnetic wire 10, but the high-frequency current applied to the magnetic wire 10 is not limited to a sine wave, and may be a rectangular pulse or the like.

Further, as shown in FIG. 6, the above-mentioned MI element is encapsulated in a molding 19 made of an insulating non-magnetic resin (eg, epoxy resin containing glass) by molding. A terminal can be packaged by protruding a terminal (mounting pin 16) derived from the magnetic wire 10 and a terminal (mounting pin 17) derived from the coil 11 outside the wire 19. Here, the tip 1 of the mounting pins 16 and 17 serves as a terminal protruding outside the molded body 19.
Since 6c and 17c are used, wire bonding is not required, and the productivity is excellent. Note that such packaging can be performed by heating and curing a resin such as an epoxy resin after powder coating, or can be formed into a shape like an IC package.

7 to 11 are views for explaining a second embodiment of the present invention. FIG. 7 is a perspective view of the MI element (magnetic sensor) according to the second embodiment in the course of assembly, and FIG. FIG. 9 is a front view of a mounting pin used in the example, FIG. 9 is a side view showing a completed MI element according to the embodiment, and FIG. 10 is an explanatory view showing a state when the MI element shown in FIG. 9 is mounted on a circuit board. FIG. 11 is a perspective view showing a state where the mounting of the MI element on the circuit board in FIG. 10 is completed. In these figures,
Parts corresponding to those in the first embodiment are denoted by the same reference numerals.

In the second embodiment, U as shown in FIG.
A total of four U-shaped magnetic wire mounting pins 20 are used, and both ends of the magnetic wire 10 placed on each solder land 13 are attached to the inner and outer mounting pins 2 as shown in FIG.
0 is temporarily fixed. That is, each of the solder lands 13 on the support substrate 12 has two mounting pins 2.
Mounting holes (not shown) for inserting the legs of the mounting pins 20 are formed, and the mounting pins 20 are inserted into these mounting holes, respectively. The end of the wire 10 can be securely clamped. Since the mounting pins 20 holding the ends of the magnetic wires 10 and the solder lands 13 are soldered in this manner, the ends of the magnetic wires 10 are securely held in the solder 15.

The legs of the two inner mounting pins 20 located at both ends of the sensing portion of the magnetic wire 10 out of the total of four magnetic wire mounting pins 20 cover the winding area of the coil 11. The support substrate 1
2 is cut before the coil 11 is wound around the coil 2. Although not shown, the second embodiment is also the first embodiment.
As in the embodiment, a resin for preventing disconnection is applied to the magnetic wire 10 and the coil 11 and cured.

In the second embodiment, the coil 11 is not soldered to the supporting substrate 12, but is soldered to the circuit board 18 as a mother board as shown in FIG. I have. As shown in FIG. 10, the circuit board 18 has an opening 2 for releasing a wound portion of the coil 11 when the support board 12 is mounted.
1 is provided.

FIGS. 12 to 14 illustrate a third embodiment of the present invention. FIG.
FIG. 13 is a front view of a mounting pin used in the embodiment, and FIG. 14 is a perspective view showing a completed MI element according to the embodiment. Parts corresponding to those in the second embodiment are denoted by the same reference numerals.

In the third embodiment, the magnetic wire mounting pins 22
Is formed in a clip shape, and the head 22a having a spring property is attached to the support substrate 12 from the side. Therefore, the mounting hole for inserting the mounting pin 22 is not formed in the support substrate 12, and the end of the magnetic wire 10 is formed by the spring property of the head 22 a of the mounting pin 22 as shown in FIG. It is sandwiched between the portion 22a and the solder land 13. In the third embodiment, the notch 12 for defining the winding range of the coil 11 is provided.
The case where a is provided on only one side of the support substrate 12 instead of both sides is illustrated.

In the third embodiment, as in the second embodiment, the magnetic wire 10 and the coil 11 are coated with a resin (not shown) for preventing disconnection.
Instead, both ends of the coil 11 are free to be soldered to a circuit board (not shown).

FIG. 15 is a perspective view of an MI element (magnetic sensor) according to a fourth embodiment of the present invention during assembly (before soldering). Parts corresponding to those of the first to third embodiments have the same reference numerals. Is attached.

In the fourth embodiment, mounting pins for temporarily fixing both ends of the magnetic wire 10 are not used, and the magnetic wire 10 is inserted into one hole provided in the solder land 13 on the support substrate 12. Is inserted and the other end of the lead wire 23 is inserted into the other hole.
And the lead wire 23 are electrically connected. At this time, the end of the magnetic wire 10 is attached to the support substrate 12 with an adhesive (not shown).
In this case, it is possible to secure the mounting strength and conduction reliability of the magnetic wire 10 having poor solder wettability. The solder lands 13 in the fourth embodiment may be provided on the back surface of the support substrate 12.

FIGS. 16 to 18 illustrate a fifth embodiment of the present invention. FIG.
FIG. 17 is a bottom view of a cover member used in the embodiment, and FIG. 18 is a perspective view showing a completed MI element according to the embodiment. 4th
Parts corresponding to those of the embodiment are denoted by the same reference numerals.

In the fifth embodiment, a cover member 24 is provided on the support substrate 12 so as to cover the magnetic wire 10, and the axis of the coil 11 wound around the cover member 24 and the support substrate 12 is aligned with the magnetic wire 10. The point that is set to approximately match,
This is significantly different from the first to fourth embodiments. The cover member 24 is made of a non-magnetic material such as PPS (polyphenylene sulfide) and is formed of an insulating resin, and has a thickness substantially equal to that of the support substrate 12. Also, the magnetic wire 10 and the magnetic wire mounting pin 1
A groove 24a is formed for preventing contact of the solder 6 with a solder 15 soldered to a solder land (not shown). In the embodiments described above, the notches for defining the winding range of the coil 11 are provided in the support substrate 12, but in the present embodiment, the notches 24b for coil positioning are provided on both side edges of the cover member 24. Is provided.

The M incorporating such a cover member 24
In the I element, since the axis of the coil 11 in the wound state and the magnetic wire 10 substantially match, the direction of the bias magnetic field generated by the coil 11 substantially matches the length direction of the magnetic wire 10. Become. As a result, a bias magnetic field of almost uniform magnitude is applied to the magnetic wire 10 over the length direction of the magnetic wire 10, so that the detection accuracy can be greatly improved.

In the fifth embodiment, the coil 11 is coated with a resin (not shown) for preventing disconnection. Also, a member similar to the cover member 24 can be incorporated in the MI element shown in the first to fourth embodiments.

Finally, an example of a drive circuit of a magnetic sensor incorporating the MI element according to the present invention will be described with reference to the circuit diagram of FIG.

In the figure, reference numerals W1 and W2 denote magnetic wires made of an amorphous wire.
1, a coil for applying a bias magnetic field to W2 and a power supply for supplying a DC current to the coil are not shown. The reason why two magnetic sensors are used is to cancel the influence of geomagnetism and the like as described later.
Symbols U1 to U6 are, for example, model number TC74HCU manufactured by Toshiba.
An inverter circuit (hereinafter, simply referred to as an inverter) housed in one C-MOS IC package such as an IC package 04. An input terminal of the inverter U1 is connected to a DC power supply Vcc of, for example, 5 V via a protection diode D1 of the inverter U1, and is also grounded to a ground level via a protection diode D2. The output terminal of the inverter U1 is connected to the input terminal of the inverter U2 and is connected to the input terminal of the inverter U1 via the resistor R1. The output terminal of the inverter U2 is connected to the input terminal of the inverter U1 via the capacitor C1 and to one end of the capacitor C2. Inverters U1, U2
The resistor R1 and the capacitor C1 constitute an oscillation circuit. The resistor R1 and the capacitor C1 are a resistor and a capacitor for setting a time constant. I can decide. The other end of the capacitor C2 is connected to a power supply Vcc via a resistor R3, is grounded via a resistor R2, and is connected to inverters U3, U4, U5, U5.
6 are connected to each input terminal. Further, a protection diode D3 is connected in parallel to the resistor R3, so that a voltage exceeding the rating is not applied to the inverters U3 to U6. Note that a differentiating circuit is formed by the capacitor C2 and the resistor R3, and the resistors R2 and R3 set the voltage level applied to the inverters U3 to U6. The input terminals of the inverters U3 to U6 are connected to each other, and the output terminals of the inverters U3 and U4 are connected to each other, and the connection terminal is grounded via a current limiting resistor R4 and a magnetic wire W1. At the same time, the output terminals of the inverters U5 and U6 are connected to each other, and the connection terminal is connected to the current limiting resistor R5 and the magnetic wire W.
2 is grounded. The resistance R4 and the magnetic wire W
1 and a connection point b between the resistor R5 and the magnetic wire W2.
Thus, the output voltages of the magnetic wires W1 and W2 can be obtained. Although not shown, these connection points a and b are connected to two input terminals (inverting input terminal and non-inverting input terminal) of the differential amplifier, and are detected from the output terminal of the differential amplifier. A signal corresponding to the magnetic field can be extracted as a voltage.

Here, the reason for using two magnetic sensors will be described. Since the magnetic sensor incorporating the MI element according to the present invention is so sensitive that it can detect terrestrial magnetism, if a magnetic field is detected using only one magnetic sensor, a disturbance magnetic field such as terrestrial magnetism is generated in the magnetic field generated from the detection target. The applied magnetic field is detected. Therefore, the magnetic wires W1, W
In the measurement, one magnetic sensor (for example, a magnetic sensor provided with a magnetic wire W1) is arranged close to a detection target, and the other magnetic sensor is used for measurement. (For example, a magnetic sensor provided with the magnetic wire W2) is placed away from the detection target. And
By taking the difference between the outputs obtained from the two magnetic sensors, it is possible to obtain a signal corresponding to a magnetic field in which a disturbance magnetic field such as terrestrial magnetism has been canceled (that is, a magnetic field generated from the detection target).

Next, the operation of the above-described drive circuit will be described. An oscillation circuit including the inverters U1 and U2, the resistor R1, and the capacitor C1 outputs a frequency determined by the resistor R1 and the capacitor C1 (eg, 400 k
Hz) (a duty ratio of about 50%) is output. This square wave signal is converted into a differential waveform (sharp rising and falling waveforms) by a differentiating circuit composed of a capacitor C2 and a resistor R3, and the voltage level of the differentiated waveform is adjusted by the resistors R2 and R3. Applied to U3 to U6. And the inverter U3
The differential waveform is inverted by U4, and a sharp pulse-shaped current is applied to the magnetic wire W1 via the resistor R4. Similarly, a sharp pulse-shaped current is applied to the magnetic wire W2 via the resistor R5 by the inverters U5 and U6. As a result, a signal corresponding to the detected magnetic field can be obtained from the output terminal of the differential amplifier (not shown) connected to the connection points a and b.

In this drive circuit, a pulse-like current is applied to the magnetic wire instead of a sine wave. This is because the impedance change of the magnetic wire due to the external magnetic field is caused by the skin effect. doing. That is, since the skin effect increases as the frequency of the current increases, it is necessary to supply a high-frequency current to the magnetic wire in order to obtain the magnetic impedance effect. However, trying to obtain a high-frequency current with a sine wave complicates the circuit configuration.
By applying a pulse-like current including a frequency component higher than the oscillation frequency to the magnetic wire, a high-frequency current is caused to substantially flow through the magnetic wire.

The larger the current flowing through the magnetic wire, the larger the output can be obtained from the magnetic wire. However, the current that can flow through the inverters U3 to U6 is determined by the characteristics of the IC (for example, one current). 2 per inverter
5 mA), two inverters U3 and U4 are connected in parallel, so that a current twice as large as that of one inverter can be supplied to the magnetic wire W1. Further, the resistor R4
Thereby, the two inverters U3 and U4 are prevented from being destroyed due to excessive current flowing. The same applies to inverters U5 and U6.

[0049]

The magnetic sensor according to the present invention is embodied in the form described above, and has the following effects.

Since the coil is wound around the support substrate that supports the magnetic wire, the magnetic sensor is more easily assembled and handled as compared with a case where the coil is wound around a tube of vinyl or the like. Also, if a pin-shaped magnetic wire attachment member, for example, which can temporarily fix the magnetic wire to the support substrate, is used, by securely soldering this attachment member to a conductive portion such as a solder land of the support substrate, The mounting strength and conduction reliability can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a support substrate used in a first embodiment.

FIG. 2 is a perspective view and a front view of a mounting pin used in the first embodiment.

FIG. 3 is an explanatory view showing an assembling procedure of the first embodiment.

FIG. 4 is an explanatory diagram showing a state in which the MI element according to the first embodiment is mounted on a circuit board.

FIG. 5 is a perspective view showing a state where the mounting of the MI element according to the first embodiment on the circuit board is completed.

FIG. 6 is a partially broken perspective view showing a case where the MI element according to the first embodiment is sealed and packaged with an insulating resin.

FIG. 7 is a perspective view of the MI element according to the second embodiment during assembly.

FIG. 8 is a front view of a mounting pin used in the second embodiment.

FIG. 9 is a side view showing a completed MI device according to the second embodiment.

FIG. 10 is an explanatory view showing a state in which the MI element shown in FIG. 9 is mounted on a circuit board.

FIG. 11 is a perspective view showing a state in which the mounting of the MI element according to the second embodiment on a circuit board is completed.

FIG. 12 is a perspective view of the MI element according to the third embodiment during assembly.

FIG. 13 is a front view of a mounting pin used in the third embodiment.

FIG. 14 is a perspective view showing a completed MI device according to a third embodiment.

FIG. 15 is a perspective view of the MI element according to the fourth embodiment during assembly.

FIG. 16 is a perspective view of the MI element according to the fifth embodiment during assembly.

FIG. 17 is a bottom view of the cover member used in the fifth embodiment.

FIG. 18 is a perspective view showing a completed MI device according to a fifth embodiment.

FIG. 19 is a circuit diagram showing an example of a drive circuit of the magnetic sensor according to the present invention.

FIG. 20 is a characteristic diagram showing a correlation between a voltage generated in a sensing portion of a magnetic wire and an external magnetic field.

FIG. 21 is a perspective view showing a conventional MI element in which a bias magnetic field applying coil is wound around a magnetic wire.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Magnetic wire 11 Coil 12 Support board 12a Notch 13,14 Solder land 13a, 14a Mounting hole 15 Solder 16,20,22 Magnetic wire mounting pin 17 Coil mounting pin 16b, 17b Through hole 18 Circuit board (mother board) 19 Sealing Stopping molded body 21 Opening 23 Lead wire 24 Cover member 24b Notch

Claims (9)

[Claims] 1. A magnetic wire whose voltage generated by applying a time-varying current changes in accordance with a change in an external magnetic field, a support substrate for supporting the magnetic wire, and the magnetic wire for applying a bias magnetic field. A coil wound around a wire, and the coil is wound around the support substrate to form the wound state. 2. The device according to claim 1, wherein a pair of conductive portions are provided on the supporting substrate and are separated from each other, and both ends of a sensing portion of the magnetic wire are electrically connected to the conductive portions. Magnetic sensor. 3. A magnetic wire mounting member according to claim 2, further comprising a magnetic wire attaching member attached to said support substrate in a state where said magnetic wire is sandwiched between said support substrate and said magnetic wire attaching member. A magnetic sensor characterized by being soldered. 4. The magnetic wire mounting member according to claim 3, wherein the magnetic wire mounting member has a pin shape having a leg, and a mounting hole for inserting the leg is provided in the support substrate. Magnetic sensor. 5. The winding state according to claim 1, wherein a cover member for covering the magnetic wire is provided on the support substrate, and the coil is wound around the cover member and the support substrate. A magnetic sensor characterized by the following. 6. The device according to claim 1, wherein a positioning portion for regulating the position of the coil and defining the winding range is provided on the support substrate or the cover member. Magnetic sensor. 7. The magnetic sensor according to claim 6, wherein the positioning portion is a notch. 8. The magnetic sensor according to claim 1, wherein the support substrate is a child substrate mounted on a mother substrate. 9. The molded body according to claim 1, wherein at least the magnetic wire, the support substrate, and the coil are sealed in a molded body made of an insulating resin. A terminal that conducts to the magnetic wire and a terminal that conducts to the coil protrude outside the magnetic sensor.