JPS63221216A - Azimuth measuring instrument - Google Patents

Abstract

PURPOSE:To reduce feeding lines to an utilized device and to improve use performance by converting a voltage corresponding to an external magnetic field detected by an earth magnetism sensor into a current, and generating and adding a current for deviation correction. CONSTITUTION:The output of the earth magnetism sensor 10 which consists of an exciting winding 12 excited by an exciting circuit 11 and a couple of orthogonal output windings 13 and 14 is led out of one of the output windings 13 and 14. A couple of terminals of the windings 13 and 14 are connected to the series circuit of an AC amplifier 15, a DC commutator 16, a DC amplifier 17, and a voltage/current converter 18, whose output is connected to the other terminal of the output winding, so the output of the magnetism sensor 10 is sent as a current signal to a display module 2. The module 2 adds the current for deviation correction to the input current signal through a voltage/current converter 25 to display earth magnetism through a microcomputer 20.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an azimuth measuring device based on measurement of geomagnetism, and in particular, it is possible to reduce the number of power supply lines for supplying electricity to each part. The present invention relates to an azimuth measuring device that can be advantageously applied to a moving body such as a car.

[Prior Art] FIG. 3 is a schematic configuration diagram of a magnetic sensor generally used in this type of direction measuring device, as described in, for example, Japanese Patent Application Laid-Open No. 55-16275. In FIG. 3, (30) is a donut-shaped ferromagnetic core, which is usually called a toroidal core, and is not limited to an annular shape, but may be rectangular. An excitation winding (31) is wound around this magnetic core (30) so as to magnetize it in the circumferential direction. On top of that, there is a magnetic core (
An output winding (32) is wound around the opposing portions of the winding (30), and a different output winding (33) is wound on top of it so as to be orthogonal to this output winding (32). ing. Here, (311) and (312) are the excitation winding (3
1), which corresponds to the output winding (32
) and (33). Now, for example, if an external DC magnetic field is applied from a direction perpendicular to the output winding (32), the part of the magnetic core (30) that intersects with the output winding (32) will absorb this external magnetic field. The so-called B-8 curve of this part is offset by the amount of this external magnetic field.

As a result, an output corresponding to the offset is obtained in the output winding (32).

Next, FIG. 4 is a block diagram showing a conventional direction measuring device of this type. In FIG. 4, the annular magnetic body (40) is provided with an excitation winding (41) and a pair of output windings II (41) and (42) which are orthogonal to each other. A magnetic sensor (4) is configured. The excitation winding (41) is provided with an excitation circuit (44) to which an oscillator (45) is attached.

Further, one output winding (42) is provided with a bandpass filter (42).
6^), an AC amplifier (47^), a rectifier (48^), and a DC amplifier (49^) are connected in series. Then, do the same for the other output winding &i (43),
A bandpass filter (46B), an AC amplifier (47B), a rectifier (48B), and a DC amplifier (49B) are connected in series.

Now, assuming that an external magnetic field H0 is applied to such an azimuth measuring device as shown in the figure, a minute voltage eu is applied to the output windings (42) and (43), respectively.
, ev is output. Then, the above-mentioned bandpass filter (46^), (46B), AC amplifier (47^), (
47B), rectifier (48^), (48B), DC amplifier (49^), (49B), DC voltage Vu, Vv
will be output and used for utilization devices such as display modules and displays (none of which are shown).

By the way, as is clear from the above explanation, since analog output is obtained as a voltage from such a conventional direction measuring device, its magnitude and sign also have meaning. , Therefore, two types of power supplies are required, positive and negative, and positive, negative and ground (common)
3” feeder cables are required. However,
When trying to install such an azimuth measuring device in a moving body equipped with only a single DC power source, such as a car or a small boat, there is no other choice but to use the single DC power source. Even in such a case, it is necessary to generate and use a predetermined reference potential consisting of either the azimuth measuring device or the device utilizing it, and therefore three power supply lines are still required. It is something that will be done.

In addition, in this type of azimuth measuring device, when performing the error correction as described above, it is necessary to attach the same number of power supply lines as the output windings provided in the magnetic sensor from the device to the azimuth measuring device. It is necessary to do so. Now, when the number of output windings is N, N wires are provided for the output signal, three wires are used for power supply, and N wires are used for correcting the difference, for a total of 2N+3 wires. is required.

In addition, in a normal direction measuring device of this type, a pair of output windings that are orthogonal to each other is often used, and in such a case, N=2, and therefore a total of seven windings are used. Electrical wires will be required.

By the way, in conventional orientation measuring devices of this type, the sensitivity coefficient and the reference voltage, which are the ratio between the external magnetic field to be measured and the corresponding output voltage, are unilaterally dependent on the orientation measuring device used. For this purpose, by changing or adjusting the constants of various electronic components in the direction measuring device, depending on the manner in which it is used,
The desired sensitivity coefficient and reference voltage are obtained.

[Problems to be Solved by the Invention] The conventional direction measuring device is configured and operated as described above, but the number of power supply lines connecting the direction measuring device and the device to be used is limited. In many cases, there is a problem that it becomes an obstacle to improving the assemblability of the device, and depending on the application, it is necessary to adjust the electronic components that make up the direction measuring device in order to appropriately set the sensitivity coefficient and reference voltage. There was also the problem that constants had to be changed or adjusted.

This invention was made in order to solve the above-mentioned problems, and it reduces the number of power supply lines connected to the equipment to be used, improves the ease of assembly, and reduces radiation noise from the power supply lines. It is an object of the present invention to provide an azimuth measuring device that improves its usability by reducing the amount of noise and has flexibility in setting sensitivity coefficients and reference voltages.

[Means for Solving the Problems] A direction measuring device according to the present invention includes a geomagnetic sensor, a means for converting a voltage corresponding to an external magnetic field detected by the geomagnetic sensor into a current, and a means for receiving and receiving the current. This includes calculation means for performing the necessary processing and deriving the current for error correction.

[Operation] In the present invention, the voltage detected by the geomagnetic sensor is converted into a corresponding current and supplied to the utilization device, and then the required arithmetic processing is performed in the utilization device to calculate the deviation. A current is generated for correction.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram showing one embodiment of the present invention. In FIG. 1, (1) is a sensor module, which outputs the detection result of earth's magnetism as a current signal. Further, (2) is a display module for displaying the traveling direction of a target moving object (not shown) using the current signal output from the sensor module (1).

First, regarding the Senna module (1), it includes a geomagnetic sensor (10). This geomagnetic sensor (, 10) has an excitation winding (12) excited by an excitation circuit (11), and an excitation winding (12) that is orthogonal to each other.
It consists of a pair of output windings (13) and (14).

One of the output windings (13) is connected to a pair of terminals (13^
), (13B>, the former is connected to the signal input terminal side of the next-stage AC amplifier (15), and the latter is connected to the analog reference terminal side of the AC amplifier (15) and the sensor module (1). The output terminal of the AC amplifier (15) is connected to the input side of the DC converter (16).
16), a synchronous detection circuit is usually used.

The output side of this DC converter (16) is connected to the input side of a DC amplifier (17) having a smoothing function.

As this DC amplifier (17), an amplifier or an integrator having low-pass characteristics is used. DC amplifier (17
) is connected to the input side of a voltage/current converter (18) consisting of one suitable resistor, and the output side of said voltage/current converter (18) is connected to said one output winding (13). ) is connected to one terminal (13^) side.

The other output winding (14) is also connected to the same means as described above, and is connected to the other final output terminal (19^) of the sensor module (1). However, since the connection relationship and mode of operation are the same as those of the one output winding (13), detailed explanation thereof will be omitted.

In a cyclic circuit configuration related to one output winding (13) as described above, when the absolute value of the so-called -cyclic transfer function is sufficiently large, the geomagnetic sensor (13)
0) in a magnetic field applied from the outside, the detection axis component (1) is detected by the one output winding (13). and the current I0 fed back to this output winding (13): 1,=kH.

A relationship is established. However, k is the geomagnetic sensor (10
) is a constant determined depending on the structure of From this, the current flow is fed back to one output winding (13). teeth,
It represents the measurement result of the magnetic field to be measured. Furthermore, this current ■. Although a portion also flows to the AC amplifier (15), its magnitude is negligible.For example, when the current I0 for a given geomagnetic field is about 121-, the amount flows to the AC amplifier (15). It is understood that the magnitude of the current is 0.1 μ8 degrees and can be ignored. Therefore, the sensor
The current obtained at one final output terminal (19) of the module (1). ′ is ■. ′ξ 工.

It can be said that

Next, regarding the display module (2), the sensor
Final output terminals (19), (19) of module (1)
Input terminals (26) and (26^) corresponding to ^), respectively
is provided, and focusing on one of the input terminals (26), it is connected to the current/voltage converter (22) and the A
It is connected to the input side of the microcomputer (20) through a series circuit consisting of a D/D converter (23), and its output side is a D/A converter (24) and a voltage/current converter (25). are connected through a series circuit consisting of

A suitable display (21) is connected to the microcomputer (20). This indicator (21)
The 0 display module (2) includes a plurality of display segments consisting of liquid crystals, light emitting diodes, lamps, etc., and is configured to display a desired direction by lighting at least one of them. The other input terminal of (
268) and the microcomputer (20),
Although the various means described above are provided, there is no particular difference in their arrangement or operation, so a detailed explanation thereof will be omitted.

One final output terminal of the sensor module (1) (
The current ro' (ζIo) obtained in step 19) is applied to the current/voltage converter (22) via one input terminal (26) of the display module 2), converted into a corresponding voltage, and then , is digitized by an A/D converter (23), and then added to the microcomputer (20). This microcomputer (20) is equipped with various necessary programs, and necessary calculation processes such as azimuth calculation and error correction calculation can be performed by selecting and selecting these programs as appropriate.
This is done by using The result of the error correction calculation is then sent to the microcomputer (20).
This is output as a digital value from the D/A converter (
24), it is converted into an analog voltage value. This voltage value is then converted into a difference correction current Ij by a voltage/current converter (25), and then added to the current I0' from the sensor module (1).

FIG. 2 is a circuit diagram of the current/voltage converter (22) in the display module (2). This current/voltage converter (22) is constructed by connecting an operational amplifier (220) and a resistor (221) with a resistance value Re. The voltage Vr applied to the positive phase input terminal (220÷) of the operational amplifier (220) is an analog reference voltage in the display module (2). Further, the resistor R0 is connected to the operational amplifier (22
0) output terminal (22-OUT) and negative phase input terminal (22-OUT)
-IN). Now, the output current 10' from the sensor module (1) and the error correction current Ij from the microcomputer (20) in the display module (2) are input to the negative phase input terminal (22-IN). Then, this negative phase input terminal (22-IN>
The potential at is Vr, and its output terminal (zz
-outT) becomes Vr-(I.' + IJ)RO. That is, at the output terminal (22-0117) of this current/voltage converter (22), a signal as a measurement result of the external magnetic field applied to the magnetic sensor (10) is output current (2). ' and the error correction arithmetic operator j, it is obtained in a format based on the reference voltage of the display module (2).

In addition, although the explanation of the above embodiment was made only for the part related to one output winding (13), as is clear from the explanation of 0 or more that is the same for the other output winding (14), the sensor Only two signal lines are required to connect the module (1) and the display module (2), and the conventional
This will be significantly reduced compared to when the output signal is in voltage form.

[Effects of the Invention] As explained above, the direction measuring device according to the present invention includes a geomagnetic sensor, a means for converting a voltage corresponding to an external magnetic field detected by the geomagnetic sensor into a current, and a means for receiving the current. The geomagnetic sensor converts the voltage detected by the geomagnetic sensor into a corresponding current. The current for correcting the difference is generated after the necessary arithmetic processing is performed in the device, so the power supply line between the device and the device is This has the advantage of requiring fewer pieces and greatly improving usability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure is a circuit diagram showing a part of the above embodiment, FIG. 3 is an illustrative diagram of a generally used annular magnetic body, and FIG. 4 is a block diagram showing a conventional example. (1) is a sensor module, (10) is a geomagnetic sensor, (11) is an excitation circuit, (13), (14) are output windings, (15) is an AC amplifier, (16) is a DC converter, ( 1
)) is a DC amplifier, (18) is a voltage/current converter, (1
9), (19^) is the output terminal on the sensor module side,
(2) is a display module, (20) is a microcomputer, (21) is a display, (22) is a current/voltage converter, (23) is an A/D converter, and (Z4) is a D/A converter. , (25) is a voltage/current converter.

Claims (1)

[Claims] (1) A geomagnetic sensor consisting of an annular magnetic body, an excitation winding wound so as to be magnetized in the circumferential direction of the annular magnetic body, and a plurality of output windings wound in the radial direction of the annular magnetic body. , a series circuit in which an AC amplifier, a DC converter, a DC amplifier, and a voltage/current converter are connected in this order, the series circuit being parallel to both terminals of each of the plurality of output windings. , and a final output terminal associated with a connection point between one terminal of each of the plurality of output windings and one input side terminal of the AC amplifier; a plurality of tip input terminals; A microcomputer, a series circuit consisting of a current/voltage converter and an A/D converter, provided between a predetermined one of the plurality of tip input terminals and a corresponding input terminal of the microcomputer. the series circuit consisting of a D/A converter and a voltage/current converter, the series circuit comprising a D/A converter and a voltage/current converter, wherein the corresponding output terminal of the microcomputer and the predetermined terminal among the plurality of tip input terminals; and an indicator connected to the output section of the microcomputer, the display module comprising: the series circuit provided between the sensor module and the output section of the microcomputer; The output terminals and corresponding ones of the plurality of tip input terminals of the display module are individually connected by signal lines, and the output current from the sensor module side and the output current are determined by the microcomputer. An azimuth measuring device that adds a difference correction current calculated based on a predetermined program to make necessary corrections to the azimuth display.