JP2535503B2 - Geomagnetic direction sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a geomagnetic direction sensor that measures weak geomagnetism with high accuracy and detects the position and direction.

[Technical background of the invention and its problems]

As a conventional geomagnetic direction sensor, the one shown in FIG. 5 is known. As shown in the figure, for example, a drive coil C _D is wound around a ring-shaped magnetic core made of permalloy,
X direction detection coil C _X and Y direction detection coil C _Y
The detection unit DET is wound so as to intersect with each other, the signal from the oscillator is input to the drive coil C _D , and the signal obtained at each detection coil C _X , C _Y based on the horizontal component of the geomagnetism at that time is Filter, AC amplifier, synchronous rectifier,
The analog outputs E _X and E _Y are obtained via a DC amplifier. The output from the oscillator is input to a synchronous rectifier via a frequency multiplication circuit and a phase variable circuit for synchronization.

As described above, the analog output E corresponding to the azimuth angle θ as shown in FIG. 6 can be obtained, and the azimuth is detected. In Figure 6, E _X is si
n curve, E _Y shows cos curve.

However, in the device having the above-mentioned configuration, since the ring-shaped magnetic core made of permalloy is used, the detection unit DET
Is large (for example, the diameter is 20 to 30 mm and the thickness is 5 to 10 mm), and a plurality of windings must be formed on the ring core, which requires a long time for assembly.
In addition, since Permalloy is used, it is weak against vibration and shock, and the secondary side induced voltage based on the frequency (for example, 500 to 2kHz) given to the drive coil as the primary side winding is output on the X-axis, Y
Since the structure is taken out as the shaft output, there is a problem that the driving frequency is low and the stability is low, and especially the drift is large.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and is resistant to vibration and shock, can be configured to be small and lightweight, and can be easily assembled.
Moreover, it is an object of the present invention to provide a geomagnetic direction sensor which can be simplified in processing circuit, can be driven at a high frequency, can reduce drift, and is excellent in stability and reliability.

[Outline of Invention]

The geomagnetic direction sensor of the present invention comprises a high-permeability magnetic core formed in an annular shape by an electrostrictive amorphous wire, and a pair of coils arranged at positions corresponding to intersections of axes of orthogonal coordinates in the high-permeability magnetic core. And a processing unit for detecting the azimuth of the geomagnetism acting on the detection unit by obtaining the difference between the detection signals from the pair of coils.

Example of Invention

 The present invention will be specifically described below with reference to examples.

FIG. 1 is a schematic view showing an embodiment of the present invention, in which, for example, 3 pieces are provided in a holder 5 having a ring-shaped (diameter of about 20 mm) groove.
Zero magnetostrictive amorphous wire (composition
Co ₆₈ Fe ₄ Si ₁₃ B ₁₅ atomic%, 110 μm diameter) AF is arranged in a ring shape to form a ring, and the X axis and the Y axis in the orthogonal coordinate axis are used.
A detection unit 1 formed by winding coils 3A, 3B, 4A, 4B around four points of the amorphous wire 2 corresponding to the intersections of the axes,
It is composed of processing circuits 2A and 2B which process outputs from the coils 3A and 3B and 4A and 4B to obtain an X-direction output E ₀₁ and a Y-direction output E ₀₂ , respectively.

Here, the magnetic amorphous wire AF may have an endless shape, but a magnetic gap may be provided in part as shown in the figure. By providing a magnetic gap, the slope of the BH curve (magnetic saturation curve) can be changed.

Since the processing circuits 2A and 2B have the same configuration, the configuration of one processing circuit 2A is shown in FIG. 2 as a specific example. This is because the signals obtained from both ends of the coils 3A and 3B arranged in the X direction, which form the detection unit 1, are passed through the signal lines l ₁ and l ₂ , respectively, and the transistors Tr ₁ and Tr ₂ and the signal lines l ₃ and l _{4 respectively.} Is input to the active filter ACF via. Each transistor Tr _1, the signal line to the base of the Tr ₂ l _1,
The output of the commutation circuit (consisting of capacitor C _B and resistor R _B ) connected to l ₂ is crossed and applied. Further, load resistances R _L and R _L are connected in series between the signal lines l ₃ and l ₄ , and a variable resistance VR is connected in parallel with the load resistances R _L and R _L.
The resistor R _L, the connection point of the R _L are commonly grounded with. The power supply voltage E is applied between the coils 3A and 3B, and the output E ₀₁ can be taken out from the active filter ACF. That is, this circuit is configured as a multivibrator bridge using an equivalent two magnetic core.

The processing circuit 2B is the same as the processing circuit 2A except that the processing circuit 2B processes signals from the other coils 4A and 4B of the detector 1. Since the two processing circuits 2A and 2B have the same configuration as described above, these processing circuits 2A and 2B
The circuit configuration of the entire 2B can be simplified.

The geomagnetic direction sensor having the above-mentioned configuration is provided with the processing circuits 2A, 2
The detection unit 1 is driven by the drive frequency set in B (for example, a higher frequency of 100 to 500 KHz than the conventional example), and the strength of the magnetic field generated in each coil 3A and 3B, 4A and 4B of the detection unit 1 at this time. Is detected by each processing circuit 2A, 2B, and is taken out as outputs E ₀₁ , E ₀₂ via the active filter ACF.

As a result of measuring the geomagnetism by the geomagnetic direction sensor having the above configuration, the relationship between the analog output Em obtained from each processing circuit 2A, 2B and the azimuth angle θ is as shown in FIG.
It was possible to obtain almost the same characteristics as with the conventional sensor.

Here, E ₀₁ = Emsin θ, E ₀₂ = Emcos θ, and when the above result is made into a rectangular coordinate figure as shown in FIG.
A slightly offset circle was obtained from. However, it was found that the deviation was within 1 ° and the detection error was extremely small.

The present invention is not limited to the above embodiment, and various modifications can be made.

For example, as shown in FIG. 4 (a), the structure of the detection unit is such that four coils 3A, 3 are formed on a square amorphous wire AF.
B, 4A, 4B may be wound, or coils 3A, 3B, 4A, 4B may be formed on each side of the amorphous wire AF bent in a polygonal shape (octagonal shape in the figure), as shown in FIG. 4A, 4
It may be a wound B. Such a shape has an advantage that more winding portions can be formed than a circular shape.

Since the geomagnetic direction sensor is a method of detecting the difference between the magnetic fields of two independent magnetic cores (choke coils), the driving frequency can be set high, and the operation can be stabilized and the drift can be reduced.

In addition, it has the advantage of being strong against vibration and shock because it uses a zero magnetostrictive amorphous wire. Furthermore, since it is a method of winding a coil around the wire, it contributes to easy winding work and miniaturization and thinning. It will be done.

〔The invention's effect〕

According to the present invention described in detail above, by virtue of the above-mentioned configuration, it is resistant to vibration and shock, and can be configured to be small and lightweight,
It is possible to provide a geomagnetic direction sensor that is easy to assemble, has a simplified processing circuit, and has reduced drift and excellent stability and reliability.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of the present invention, FIG. 2 is a circuit diagram showing an example of its processing circuit section, FIG. 3 is a characteristic diagram showing the effect of the present invention, and FIGS. 4 (a) and 4 (b). ) Is a schematic diagram showing another example of the present invention, FIG. 5 is a schematic diagram of a conventional device, FIG. 6 is a characteristic diagram showing the measurement results, and FIG. 7 is a diagram showing the measurement results in a rectangular coordinate diagram. . 1 ... Detector, 2A, 2B ... Processing circuit, 3A, 3B, 4A, 4B ... Coil, AF ... Magnetic core.

Claims (2)

(57) [Claims] 1. A detection unit comprising a high-permeability magnetic core formed of an electrostrictive amorphous wire in an annular shape, and a pair of coils arranged at positions corresponding to intersections of axes of orthogonal coordinates in the high-permeability magnetic core. And two processing circuits that detect the difference between the detection signals from the pair of coils and detect the direction of the geomagnetism acting on the detection unit. 2. The geomagnetic direction sensor according to claim 1, wherein the high-permeability magnetic core of the detecting portion is formed in a polygonal shape.