JP2003329750A - Magnetic sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flux gate type magnetic sensor for low noise, with upsizing of a sensor form suppressed to the utmost. <P>SOLUTION: Two O-ring like cores 1a and 1b are provided, and they are wound with excitation coils 2a and 2b. The entire cores 1a and 1b is wound with a single detection coil 3. The excitation coils 2a and 2b may individually drive the cores 1a and 1b in parallel, drive the cores 1a and 1b in series in serial connection, or collectively drive the cores 1a and 1b with a single excitation coil. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention
G-type magnetic sensor. [0002] 2. Description of the Related Art A well-known ring core is used.
The flux gate type magnetic sensor is as shown in FIG.
And one excitation coil 2 on a flat ring-shaped core 1.
And one detection coil 3 are wound.
You. In this type of magnetic sensor, the number of turns of the exciting coil is already
Parameters are set to optimal conditions such as frequency and excitation frequency
If so, further reduce the noise of the magnetic sensor.
Therefore, the core diameter was increased. [0003] SUMMARY OF THE INVENTION
Drive parameters are set to optimal conditions.
If you try to further increase the S / N ratio in a state where
There was a problem that it was unavoidable. How to enlarge
In addition to this, as a method to increase the S / N ratio, a new core
There is a way to develop and investigate materials, but this is
There is a problem that requires time. The present invention has been made in view of the above problems.
And minimizing the size of the sensor as much as possible.
With the aim of providing a magnetic sensor that realizes low noise
are doing. [0005] A magnetic sensor according to the present invention.
Is a core, an exciting coil wound around the core,
A magnetic sensor having a detection coil wound around a core.
A plurality of said cores;
One detection coil is wound all over. To reduce the noise of the sensor, a detection coil
Times the excitation frequency in proportion to the magnitude of the external magnetic field
Frequency voltage V_2fOf Barkhausen when magnetized core and core material
Sound V _nIt is necessary to improve the ratio (S / N). Already one
V for the case of_2fOptimal to take out efficiently
The drive parameters have been obtained.
There is no room for improving data. Therefore, the noise V_nHow
The point is to make it smaller. In the present invention, a plurality of (i) cores are used.
I use it. Use i cores as in this invention
And if the Barkhausen noise is random noise,
Total V of noise detected by detection coil_nIs the noise of each core
To V_niThen V_n= √ (ΣV_ni ^Two) @IV_n1 and
Become. On the other hand, the detected V_2fIs almost proportional to the cross-sectional area of the core material
For example, since i-times detection is performed, S / N becomes √i (√
I) improvement by a factor of two. [0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The light will be described in more detail. FIG. 1 shows one embodiment of the present invention.
Showing the configuration of a fluxgate type magnetic sensor
It is a schematic diagram. This embodiment magnetic sensor has two O phosphorus
Excitation cores 2a, 2b
Are wound around the cores 1a and 1b, respectively.
a and 1b are driven in parallel. The detection coil 3 includes a core 1a,
1b is wound all together. Flux according to another embodiment of the present invention
FIG. 2 shows a schematic diagram of the configuration of the gate type magnetic sensor. This
The magnetic sensor also has two O-ring-shaped cores 1.
a and 1b. Excitation coil for cores 1a and 1b
2a and 2b are wound, respectively,
a, 2b are connected in series with each other,
b is driven in series. The detection coil 3 is similar to FIG.
The cores 1a and 1b are collectively wound as a whole. [0010] A flux according to another embodiment of the present invention.
FIG. 3 shows a schematic diagram of the configuration of the gate type magnetic sensor.
You. The magnetic sensor of this embodiment also has two O-ring-shaped cores.
1a and 1b. These cores 1a and 1b
Has one excitation coil 2 wound as a whole,
The cores 1a and 1b are collectively driven by the exciting coil 2.
You. The detection coil 3 includes the magnetic sensor shown in FIGS.
Similarly, the cores 1a and 1b are collectively wound as a whole.
I have. FIG. 4 is a flowchart showing another embodiment of the present invention.
FIG. 3 is a diagram illustrating the structure of a lux gate type magnetic sensor.
4A is a side view, and FIG. 4B is a view of FIG.
The inside of the case body when viewed along the cutting line AA in FIG.
FIG. The magnetic sensor according to this embodiment includes a case body.
4, two cores 1a, 1 having an exciting coil 2 wound inside
b is housed, and a detection coil is
3 is wound. However, this embodiment magnetic sensor
Is a new type except that two cores are stored in the case body 4.
It has no features. The magnetic sensor of this embodiment has a box structure.
And the outer dimensions of the cores 1a and 1b used are
Since the thickness / diameter ratio is about 1/6,
A), but the other two sides are core 1
It can be accommodated in the same dimensions as in the case of individual pieces. By the way,
To increase the core diameter and improve the S / N by a factor of two,
If the maximum excitation magnetic field is the same, the core diameter should be approximately 2
Need to double. [0013] According to the present invention, a plurality of cores are provided,
One detection coil is wound around the plurality of cores.
Therefore, while suppressing the sensor size from increasing,
Low noise can be achieved. Also, even with one kind of core
Various types of magnetic sensors can be manufactured just by changing the number used
can do. Also required by changing the number of cores
The expected noise level can be achieved with simple calculations.
You. Also, if an already established core is used,
It is sufficient to set with almost the same drive parameters.
The man-hours for deriving parameters can be significantly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a configuration of a fluxgate magnetic sensor according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a configuration of a flux gate type magnetic sensor according to another embodiment of the present invention. FIG. 3 is a schematic view showing a configuration of a flux gate type magnetic sensor according to still another embodiment of the present invention. FIG. 4 is a view schematically illustrating a fluxgate type box-shaped magnetic sensor according to still another embodiment of the present invention. FIG. 5 is a schematic view showing the structure of a conventional flux gate type magnetic sensor. [Description of Signs] 1, 1a, 1b O-ring-shaped core 2, 2a, 2b Exciting coil 3 Detecting coil 4 Case body

Claims (1)

Claims: 1. A magnetic sensor comprising a core, an exciting coil wound around the core, and a detection coil wound around the core, wherein a plurality of the cores are provided. A magnetic sensor, wherein one detection coil is wound around a plurality of cores.