JP2565170Y2 - Direction detection device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an azimuth detecting device suitable for use in a navigation system mounted on an automobile.

[0002]

2. Description of the Related Art In general, in a car navigation system using azimuth information by radio waves from artificial satellites, CD-ROM mapping information, and the like, a current travel position, travel guidance, and the like are input by inputting a destination in advance. Information can be easily known. However, depending on the driving area, stable reception of azimuth information is not possible due to poor reception of radio waves.Therefore, such a navigation system usually detects terrestrial magnetism and complements azimuth detection to compensate for unstable azimuth information. Equipment.

Conventionally, this type of azimuth detecting device has an X-direction detecting coil having an X-direction axis and a Y-direction having a Y-direction axis with respect to a toroidal core having a Z-direction axis wound with an exciting coil. A fluxgate type (double frequency modulation type) magnetic sensor having a direction detection coil (see reference numeral 2 in FIG. 3), and a detection signal of each detection coil in the magnetic sensor is processed to output an output value corresponding to a direction. The obtained signal processing system was provided. In particular, the signal processing system was configured as shown in FIG.

Next, the configuration and operation of such a signal processing system will be described with reference to FIGS. In FIG. 4, reference numeral 51 denotes an X-direction detection coil of the magnetic sensor. If the excitation coil (see reference numeral 2b in FIG. 3) is excited by a pulse excitation signal Sb of 5 to 10 kHz shown in FIG. 5B, a detection signal Sx shown in FIG. 5B is obtained, and the detection signal Sx is applied to a pair of signal circuits 53p and 53n connected in parallel via an amplifier circuit 52. Each of the signal circuits 53p and 53n is connected with an analog switch 54p and 54n, respectively. If one of the analog switches 54p is controlled by an open / close control signal Sp shown in FIG. ), Only the positive component Sxp of the detection signal Sx passes,
If the other analog switch 54n is controlled by the open / close control signal Sn shown in FIG.
Only the negative component Sxn of the detection signal Sx shown in FIG. Further, integrating circuits 55p and 55n are connected to the subsequent stages of the analog switches 54p and 54n in the signal circuits 53p and 53n, respectively, and the components Sxp and Sxn are integrated by the integrating circuits 55p and 55n. At this time, since each of the integration circuits 55p and 55n is controlled by the set signal Ss and the reset signal Sr shown in FIG. 5 (G), the output of each of the integration circuits 55p and 55n is repeated in units of several msec. ) And (I) to obtain the sawtooth integrated output signals Sop and Son, respectively. The inclination angle of the signal waveform in each of the integrated output signals Sop and Son changes according to the azimuth. In addition, each integration circuit 55p, 55n
In, different constants are set to reduce the relative error between the components Sxp and Sxn. On the other hand, the respective integration output signals Sop and Son are added by the adding circuit 56, and FIG.
5 (J), the instantaneous value near the maximum value of the output signal So is held by the hold circuit 57 by the latch signal Sh shown in FIG.
An output value corresponding to the azimuth is obtained from the output circuit 58.

[0005]

However, the above-described conventional azimuth detecting device requires two integrating circuits 55p and 55n corresponding to the positive component Sxp and the negative component Sxn of the detection signal Sx, and an addition circuit. 56 is required. For this reason, there has been a problem that the circuit configuration becomes complicated, the number of parts increases, and the cost and size of the device increase.
Especially when the device is built into the navigation system,
Large size is one of the most important issues due to the limited space for mounting vehicles.

The present invention solves the problems existing in the prior art. By simplifying the circuit configuration, the number of parts can be significantly reduced, the cost can be reduced, and the size and size can be reduced. It is an object of the present invention to provide an azimuth detecting device capable of improving accuracy.

[0007]

The present invention provides an exciting coil 2b.
Flux-gate type in which an X-direction detection coil 2x having an X-direction axis and a Y-direction detection coil 2y having a Y-direction axis are disposed with respect to a toroidal core 2c having a Z-direction axis wound around the coil. A magnetic sensor 2, an excitation circuit 3 that excites the excitation coil 2b with a pulse excitation signal Sb, and a detection signal S of at least the detection coil 2x (the same applies to the 2y side).
A signal processing system 4x having a pair of signal circuits 5xp and 5xn for separating x into a positive component Sxp and a negative component Sxn for signal processing and an integrating circuit 6x for integrating the separated positive component Sxp and negative component Sxn. In configuring the azimuth detecting device 1 provided, in particular, both of the signal circuits 5xp and 5xn are connected to one input portion 7a of the single operational amplifier 7, and the integration resistors 8p and 5p are respectively connected to the signal circuits 5xp and 5xn. , 8n and an integrating circuit 6x in which an integrating capacitor 9 is connected between one input section 7a and output section 7b of the operational amplifier 7.

[0008]

According to the azimuth detecting device 1 according to the present invention, the flux gate type magnetic sensor 2 has the exciting coil 2b excited by the pulse exciting signal Sb supplied from the exciting circuit 3,
As a result, a detection signal Sx whose magnitude changes in accordance with the azimuth is obtained from the X-direction detection coil 2x (the same applies to the 2y side). The detection signal Sx is subjected to signal processing by the signal processing system 4x, and an output value corresponding to the direction is obtained from the signal processing system 4x.

In this case, a detection signal Sx obtained from the detection coil 2x is separated into a positive component Sxp and a negative component Sxn by a pair of signal circuits 5xp and 5xn, and the signal Sx is supplied to a single unit through different integration resistors 8p and 8n. It is provided to one input unit 7a of the operational amplifier 7. Thereby, the integration circuit 6x
An integrated output signal obtained by integrating a signal obtained by synthesizing the positive component Sxp and the negative component Sxn is obtained as the output of. The integrated output signal is obtained by adding a signal obtained by individually integrating the positive component Sxp and the negative component Sxn. The output signal becomes the same as the integrated output signal obtained, and the number of integration circuits is reduced by half and the addition circuit is not required as compared with the related art. Further, the detection accuracy can be increased by simplifying the circuit.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will now be described in detail with reference to the drawings.

First, in order to clarify the present invention, an overall schematic configuration of the azimuth detecting device 1 will be described with reference to FIG.

In FIG. 3, reference numeral 2 denotes a flux gate type (double frequency modulation type) magnetic sensor, which includes a toroidal core 2c wound with an exciting coil 2b, an X direction detection coil 2x, and a Y direction detection coil 2y. X direction detection coil 2
The x- and Y-direction detection coils 2y are respectively wound in a ring shape, are arranged in a right angle relationship with their centers being aligned, and the axis of the X-direction detection coil 2x is in the X direction, and
The axes of the direction detection coils 2y are relatively arranged so as to be in the Y direction. Furthermore, the toroidal core 2c is disposed inside the X direction detection coil 2x and the Y direction detection coil 2y,
The centers are aligned and the axes are relatively arranged so as to be in the Z direction. Therefore, the magnetic sensor 2 in FIG.
It is displaced in the direction of arrow A so as to face east, west, north and south. The direction of the geomagnetism is indicated by an arrow F.

On the other hand, an excitation circuit 3 has a function of exciting the excitation coil 2b by supplying a pulse excitation signal Sb to the excitation coil 2b.

On the other hand, 4x and 4y are two signal processing systems, and supply detection signals Sx and Sy from the detection coils 2x and 2y to their input sides. The output sides of the signal processing systems 4x and 4y are connected to the azimuth calculation unit 15. The azimuth calculation unit 15 obtains the final azimuth information Do from the output value corresponding to the azimuth obtained by each of the signal processing systems 4x and 4y, and gives it to, for example, a display unit or a data processing unit (not shown).

Next, the configuration of a signal processing system constituting a main part of the azimuth detecting device 1 according to the present invention will be specifically described with reference to FIG. Note that the two signal processing systems 4x, 4x
Since y has the same basic configuration, only one signal processing system 4x will be described below.

In FIG. 1, reference numeral 2x denotes an X-direction detection coil for detecting the azimuth in the north-south direction, and this detection coil 2x is connected to the input side of the amplifier circuit 21. The output side of the amplifier circuit 21 is connected to the input side of an integration circuit 6x having a pair of signal circuits 5xp and 5xn connected in parallel. That is, each of the signal circuits 5xp and 5xn includes an integral resistor 8p and 8n, one end of each of the integral resistors 8p and 8n is connected to the output side of the amplifier circuit 21, and the other end of each of the integral resistors 8p and 8n is analog. Connected to one end of switches 22p and 22n. Note that each of the integration resistors 8p and 8n may be a fixed resistor whose resistance value is selected in advance, but it is preferable that each resistance value can be arbitrarily varied by using a variable resistor.
In this case, the gain of each of the signal circuits 5xp and 5xn can be set by varying each of the resistance values of each of the integration resistors 8p and 8n.
The relative error of the signal component flowing to n can be reduced. Also,
In FIG. 1, Sp and Sn are analog switches 22p and 22p, respectively.
3 shows an open / close control signal for controlling n.

On the other hand, each analog switch 22p, 22n
Are connected to an inverting input section 7a of the operational amplifier 7, and an integrating capacitor 9 is connected between the inverting input section 7a and the output section 7c of the operational amplifier 7. The non-inverting input section 7b of the operational amplifier 7 is grounded. On the other hand, the output section 7c of the operational amplifier 7 serving as the output section of the integration circuit 6x is connected to the input side of the hold circuit 23, and
3 is connected to the input side of the output circuit 24. The output side of the output circuit 24 is connected to the azimuth calculation unit 15 described above.

Next, the operation of the azimuth detecting device 1 including the signal processing system 4x will be described with reference to FIGS.

First, the excitation coil 2b is excited by a pulse excitation signal Sb of 5 to 10 kHz shown in FIG.

On the other hand, if it is assumed that the X-direction detecting coil 2x detects the north-south azimuth, the X-direction detecting coil 2x receives the positive side shown in FIG. The detection signal S including the component Sxp and the negative component Sxn
Get x. The detection signal Sx is applied to the amplifier circuit 21 and after being amplified, is applied to the integration resistors 8p and 8n in the pair of signal circuits 5xp and 5xn.

Since the analog switch 22p in one signal circuit 5xp is controlled by the open / close control signal Sp shown in FIG. 2C, only the positive component Sxp of the detection signal Sx shown in FIG. The signal passes through the signal circuit 5xp and is applied to the inverting input section 7a of the operational amplifier 7, and the analog switch 2 in the other signal circuit 5xn
Since 2n is controlled by the opening / closing control signal Sn shown in FIG. 2D, only the negative component Sxn of the detection signal Sx shown in FIG.
To the inverting input section 7a. Therefore, each component Sx
p and Sxn become alternating signals synthesized in the inverting input unit 7a and are integrated by the integration circuit 6x.

In this case, since the integrating circuit 6x is controlled by the reset signals Ss and Sr shown in FIG. 2 (E), the output of the integrating circuit 6x has several milliseconds as shown in FIG.
Sawtooth-shaped integrated output signal Sm repeated at c periods
Get. Note that the inclination angle of the signal waveform in the integrated output signal Sm changes according to the azimuth.

As for the integrated output signal Sm, the instantaneous value near the maximum value of the integrated output signal Sm is held by the hold circuit 23 by the latch signal Sh shown in FIG.
Output to the outside via the output circuit 24. The output value from the output circuit 24 is a value corresponding to the direction.

On the other hand, the Y-direction detection coil 2y detects the azimuth in the east-west direction, and the signal processing system 4y functions (operates) in the same manner as the signal processing system 4x described above.

Although the embodiment has been described in detail above, the present invention is not limited to such an embodiment, and can be arbitrarily changed in a detailed circuit configuration or the like without departing from the gist of the present invention.

[0026]

As described above, according to the present invention, an X-direction detection coil having an X-axis and a Y-axis having a Y-axis are provided for a toroidal core having an Z-axis and wound with an exciting coil. A fluxgate magnetic sensor having a direction detection coil, an excitation circuit that excites the excitation coil by a pulse excitation signal, and separates at least a detection signal of each detection coil into a positive component and a negative component to perform signal processing. In an azimuth detecting device including a pair of signal circuits and a signal processing system having an integrating circuit for integrating separated positive and negative components, both signal circuits are connected to one input unit of a single operational amplifier. In addition, the integration of an integrating resistor is connected to each signal circuit, and an integrating capacitor is connected between one input and output of the operational amplifier. By a significant reduction in the number of parts,
In particular, there is a remarkable effect that the integration circuit can be halved and the addition circuit can be eliminated, the cost and size of the entire apparatus can be reduced, and the detection accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a signal processing system of an azimuth detecting device according to the present invention;

FIG. 2 is a time chart of signals in each section of the signal processing system,

FIG. 3 is an overall schematic configuration diagram of the azimuth detecting device,

FIG. 4 is a block circuit diagram of a signal processing system of an azimuth detecting device according to the related art;

FIG. 5 is a time chart of signals in each part of the signal processing system,

[Explanation of symbols]

 Reference Signs List 1 direction detection device 2 flux gate magnetic sensor 2b excitation coil 2c toroidal core 2x X direction detection coil 2y Y direction detection coil 3 excitation circuit 4x signal processing system 5xp signal circuit 5xn signal circuit 6x integration circuit 7 operational amplifier 7a one input of operational amplifier Section 7c output section of operational amplifier 8p integration resistance 8n integration resistance 9 integration capacitor Sb pulse excitation signal Sx detection signal Sxp positive component Sxn negative component

Claims (1)

(57) [Scope of request for utility model registration] An X-direction detection coil having an X-direction axis and a Y-direction detection coil having a Y-direction axis are disposed on a toroidal core having a Z-direction axis around which an exciting coil is wound. A flux gate type magnetic sensor, an excitation circuit for exciting the excitation coil by a pulse excitation signal, and a pair of signal circuits for separating and processing at least a detection signal of each detection coil into a positive component and a negative component, and a separated signal circuit. In an azimuth detecting device including a signal processing system having an integrating circuit for integrating a positive component and a negative component, both of each signal circuit are connected to one input unit of a single operational amplifier, and each signal circuit is connected to each signal circuit. An azimuth detecting device comprising an integrating circuit to which an integrating resistor is connected and an integrating capacitor connected between one input section and an output section of an operational amplifier.