JP2617498B2 - Magnetic sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention can detect the presence or absence, magnitude, angle, etc. of a magnetic field, and can be used as a direction sensor, a position sensor, a tilt sensor, a current sensor, and the like. About.

(Prior Art) In a conventional magnetic sensor, as shown in FIG. 15, an exciting winding 2 and a detecting winding 3 are wound around a magnetic core 1, and an AC current is supplied to the exciting winding 2 by a power supply 4. Accordingly it generates an internal magnetic field H _i to the magnetic core 1 in the axial direction of the magnetic core, the magnitude of the external magnetic field H _o acting as a bias with respect to said internal magnetic field H _i, the output terminal 5 of the detection winding 3 Is configured such that the output voltage of the fundamental wave or the harmonic wave appearing in the above changes. The magnetic sensor, for example intended to be used as a current sensor, a change in the magnitude of the external magnetic field H _o that varies with the magnitude of the current can be detected as a change in the output voltage.

FIG. 16 shows a change of the application of the magnetic sensor shown in FIG. 15, in which an external magnetic field generating means such as a magnetic sensor or a magnet is arranged so that the relative orientation between the magnetic core 1 and the external magnetic field Ho changes. , to the internal magnetic field H _i of the magnetic core 1, core 1 of the external magnetic field Ho
The change in the component H _o .cos θ in the same direction appears as a change in the output voltage. This magnetic sensor is used alone or in combination of a plurality of magnetic sensors as an orientation sensor, an inclination sensor, and the like.

Magnetic sensor shown in FIG. 15 and FIG. 16, as shown in Figure 17 (A), to the internal magnetic field H _i, becomes parallel direction of the magnetic flux of the external magnetic field H _o, in FIG. 17 (B) As shown,
Magnetic field strength is maximized when the direction of the external magnetic field H _o and the internal magnetic field H _i is the same, becomes minimal becomes the opposite direction as shown in (C), is not the change can be detected as an output voltage.

In addition to the above, there is a conventional magnetic sensor using a Hall element.

As a conventional magnetic sensor, as shown in FIG. 14, a magnetic body 10b such as a ferrite or an amorphous alloy is fixed around a conductor 10a such as a metal, or a magnetic body 10b is formed separately. Insert the conductor 10a and insert the magnetic body 10b
A power supply 1 for passing a pulse current or an alternating current to the conductor 10a is provided at both ends of the conductor 10a.
1 is connected, and terminals 13 are connected to both ends of the detection winding 12.

(Problems to be Solved by the Invention) Among the above-mentioned conventional magnetic sensors, the one shown in FIGS. 15 and 16 requires two windings, an excitation winding 2 and a detection winding 3, and has a structure. Is complicated. Further, the magnetic sensor using the Hall element has a problem that the sensitivity is poor.

Further, as shown in FIG. 14, a structure having a magnetic body 10b provided around a conductor 10a requires two members, a conductor 10a and a magnetic body 10b. A step of providing the body 10b is required, and there is a problem that it is difficult to reduce the price due to an increase in material cost and an increase in the number of manufacturing steps.

What is the purpose of the present invention? In view of the above problems, a high sense of detection is high, and the number of parts, the number of manufacturing steps are reduced, the configuration is simplified,
It is an object of the present invention to provide a magnetic sensor that can achieve weight reduction and reduce cost.

(Means for Achieving the Object) In order to achieve the above object, a magnetic sensor according to the present invention comprises a linear, band-shaped or rod-shaped magnetic material having conductivity, and a pulse current or an alternating current applied to the magnetic material in a longitudinal direction. And a detection winding wound around the magnetic body. An external magnetic field is detected as an electric signal generated in the detection winding by a magnetic field generated in a circumferential direction of the magnetic body by the pulse current or the alternating current. It is characterized by having the structure which does.

(Operation) The magnetic sensor of the present invention uses a conductive material as a magnetic material, and also uses the magnetic material as a current-carrying conductor. Also, since the detection winding is wound closer to the conductor, the electromagnetic action becomes direct and the detection sensitivity is improved.

FIG. 1 shows an embodiment of a magnetic sensor according to the present invention.
The magnetic sensor of this embodiment includes a linear or rod-shaped magnetic body 10 having conductivity, a power supply 11 as a means for passing a pulse current or an alternating current to the magnetic body 10 in a longitudinal direction, and a winding around the magnetic body 10. consists Spun detection winding 12. as shown in Figure 2, to generate an internal magnetic field H _i in the circumferential direction of the magnetic body 10 by the pulse current or alternating current, the internal magnetic field
By H _i is used for detecting an external magnetic field H _o as an electric signal generated in the detection coil 12.

Figure 3, when passing a pulse current to the magnetic member 10 by a voltage pulse E _i to be generated by the power source 11, when the external magnetic field H _o is in a different direction as the internal magnetic field H _i, the output of the detection winding 12 and shows the output voltage E _o appearing at terminal 13, at the rising or falling of the pulse current, pulse height H of the voltage E _o appearing at the output terminal 13, the following intensity is predetermined magnitude of the external magnetic field H _o If so, the greater its strength,
In addition, the orientation of the external magnetic field H _o is Hododai close to the direction of the magnetic body 10.

[Example 1] An amorphous wire (wire diameter 125 µm, length 65 mm) made of a Co-based magnetic material and having no magnetostriction was used as the magnetic body 10, and a detection winding 12 was wound around the magnetic body 10 for 200 turns to reduce the horizontal component of geomagnetism. On the other hand, the amorphous wires were arranged on the non-magnetic substrate so as to be parallel. A pulse having an amplitude of 2 V, a duty factor of 50%, and a repetition period of 10 μs was applied to both ends of the amorphous wire. In this state, when the magnetic body 10 was rotated clockwise while being kept horizontal, the voltage appearing at the terminal 13 changed as shown in FIG. FIG.
The direction of the magnetic body 10 is 0 degree with respect to the horizontal component of
Degrees, 180 degrees, and 270 degrees, and the output voltage (peak value, the same applies hereinafter) is 0 degrees, 180 degrees, that is, the magnetic substance 1
When the direction of 0 is the same as the horizontal component of terrestrial magnetism, it becomes maximum, and the polarity of the output voltage is reversed. The output voltage is 90
Degrees, 270 degrees, that is, when the direction of the magnetic body 10 is perpendicular to the horizontal component of the geomagnetism.

FIG. 5 shows the relationship between the rotation angle of the magnetic body 10 with respect to the horizontal component of the terrestrial magnetism and the output voltage (output voltage generated at the rising portion of the applied rectangular voltage pulse), and draws a cosine curve.

From such a relationship between the rotation angle of the magnetic body 10 and the output voltage, this magnetic sensor is an azimuth sensor (however, it is unknown to which side east or west it is inclined) or a magnetic field generated by a magnet or the like. A tilt sensor that determines the tilt of the magnetic body 10 with respect to the direction of the current, a current sensor that uses that the output voltage is proportional to the external magnetic field strength, or a magnetic body 10 or a magnet attached to a movable body and a stationary body, respectively. It can be used for a position sensor or a rotation sensor or the like in which an output appears when an object faces a magnet or the like.

The amorphous wire having the diameter and the material described above was used as the material of the magnetic body 10, the length of the magnetic body 10 was changed in a range of 40 mm to 130 mm, the number of turns of the detection winding 12 was set to 200 turns (the same pitch), and repeated. Period 10μs, Duty factor 50
When a constant current pulse of% was passed through the magnetic body 10, a change in the output voltage when the magnetic body 10 was oriented in the direction of the horizontal component of terrestrial magnetism was examined. As a result, as shown in FIG. 6, a result was obtained that the output voltage slightly increased as the magnetic body length increased.

FIG. 7 is a diagram showing the relationship between the input voltage and the output voltage. In this case, the material and diameter of the magnetic body 10 are the same as described above.
The length was 65 mm (the diameter resistance of the magnetic material 10 was 12Ω), the repetition period was 10 μs, and the duty factor was 50%.
The variation of the output voltage when the magnetic body 10 is directed in the direction of the horizontal component of the terrestrial magnetism is examined by changing the amplitude of the input voltage in the range of 0.5 V to 2.0 V. It can be seen from FIG. 7 that the output voltage increases in proportion to the increase of the input voltage, that is, the input current, up to near 2v.

FIG. 8 shows that, under the test conditions in FIG. 7, the amplitude of the input voltage is 2 V, and the repetition period is 4 μs to 100 μs.
Indicates the change of the output voltage when the output voltage is changed to the above, and the output voltage does not largely change depending on the repetition period.

[Embodiment 2] As the magnetic body 10, a thin strip having a width of 1 mm and a thickness of 15 μm was used as the magnetic material 10 of the first embodiment, and a detection winding 12 of 200 turns was wound. As a result of measuring the sensitivity to geomagnetism with the circuit of No. 1, the same tendency as that of the wire was shown.

The length of the band-shaped magnetic body 10 was 38 mm (the DC resistance of the magnetic body 10 was 3Ω), the amplitude of the input voltage was 0.5 V, the repetition period was 25 μs, and the voltage of the duty factor 50% was applied to the magnetic body 10. And the rise time is 0.5 μs to 2.0 μs.
FIG. 10 shows the change of the output voltage when it is changed in the range of s. As can be seen from FIG. 9, the tendency that the output voltage becomes higher as the rise time of the input pulse becomes shorter becomes remarkable.

[Embodiment 3] As shown in Fig. 10, two magnetic strips having the same material and dimensions as those of Embodiment 2 were used.
The detection windings 12x and 12y are wound 200 turns around 10y and are arranged orthogonally. The magnetic material 10x and 10y are connected in series to the power supply 11, the amplitude is 2V, the duty factor is 50%, and the repetition period is 25μs. Then, the magnetic bodies 10x and 10y were kept horizontal and rotated clockwise, and the output voltages Ex and Ey of the detection windings 12x and 12y were measured. As a result, the output changed as shown in FIG. FIG. 11 shows the magnetic material 10 as shown in FIG.
FIG. 11 is a diagram showing a change in output voltage Ex, Ey when the rotation angle is changed, where the rotation angle is changed to zero degree when x and 10y are arranged. As shown in FIG.
Since the combination of the polarity and value of Ex and Ey is uniquely determined, this cross-shaped magnetic sensor can be used as a direction sensor.

FIG. 12 is an example of a processing circuit of the magnetic sensor shown in FIG. 10, in which the peak values after phase detection of each output voltage Ex and Ey are held by sample and hold circuits 14x and 14y, respectively, and the respective voltage values are held. The digital signals are converted into digital values by A / D conversion circuits 15x and 15y, and the azimuth signal is calculated by a microcomputer 16, for example, and is displayed by a display 17 attached to the microcomputer 16. It is a matter of course that various circuits other than those shown in FIG. 12 are used as the processing circuits for the output voltages Ex and Ey.

FIG. 13 shows another embodiment of the present invention, in which a magnetic film 21 is formed on a substrate 20 of alumina or the like by a film forming technique.
At the same time, a detection winding 22 is wound around the magnetic film 21, the power is supplied to the magnetic film 21 from the power supply 11, and an external magnetic field is detected as an electric signal generated in the detection winding 22.

In the above embodiment, the example in which the rectangular voltage pulse from the power supply 11 is applied to the magnetic body 10 has been described. However, a voltage having another waveform such as a triangular wave or a sine wave may be applied. In addition, as the magnetic body 10, in addition to the above-mentioned amorphous alloy having conductivity and high magnetic permeability and high saturation magnetic flux density, permalloy having similar characteristics is preferable. A thing may be used.

(Effect of the Invention) As described above, the magnetic sensor of the present invention uses a magnetic material as a conductor by using a conductive material as a magnetic material, and winds a detection winding around the magnetic material to form a magnetic sensor. A pulse current or an AC current is directly passed through the body, and an external magnetic field is detected as an electric signal generated in the detection winding by a magnetic field generated in a circumferential direction of the magnetic body by the pulse current or the AC current. The excitation winding required for the magnetic sensor having a core is not required, and a conductor for passing a pulse current or an alternating current is not required.
The number of parts and the number of manufacturing steps are reduced, the configuration is simplified, and in the case of an azimuth sensor, for example, a magnetic body can be realized by the thin wire as described above. , The weight can be reduced to about 1/10 to 1/100 and can be provided at a low price. Further, a light-weight and high-sensitivity magnetic sensor can be realized, and the magnetic sensor can be used for detecting a minute magnetic field.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a magnetic sensor of the present invention,
FIG. 2 is a diagram for explaining the principle of the present invention, FIG. 3 is a waveform diagram showing an example of the relationship between the input voltage and the output voltage in the present invention, and FIG.
FIG. 5 is a photograph showing the output voltage waveform corresponding to each rotation angle in the embodiment of FIG. 1, FIG. 5 is a diagram showing the relationship between the rotation angle and the output voltage in the embodiment of FIG. 1, and FIG. FIG. 7 is a relationship diagram between an input pulse voltage and an output voltage in the embodiment, FIG. 8 is a relationship diagram between a repetition period and an output voltage in the embodiment, FIG. FIG. 9 is a diagram showing the relationship between the input pulse rise time and the output voltage in the case where a band-shaped magnetic material is used. FIG. 10 is a configuration diagram showing another embodiment of the present invention in which the magnetic material is orthogonalized. FIG. 12 is a diagram showing the relationship between the rotation angle and the output voltage in the embodiment, FIG. 12 is an example of a processing circuit of the embodiment, FIG. 13 is a perspective view showing another embodiment of the present invention, and FIG. FIGS. 15 and 16 are diagrams showing a conventional magnetic sensor, FIGS. 15 and 16 are configuration diagrams showing a conventional magnetic sensor, and FIGS. It is a principle diagram of the conventional magnetic sensor.

Claims (1)

(57) [Claims] 1. A linear, band-shaped or rod-shaped magnetic material having conductivity, means for supplying a pulse current or an alternating current to the magnetic material in a longitudinal direction, and a detection winding wound on the magnetic material. A magnetic sensor having a configuration in which an external magnetic field is detected as an electric signal generated in the detection winding by a magnetic field generated in a circumferential direction of the magnetic body by the pulse current or the alternating current.