JPH02205716A - Magnetoelectric transducer device - Google Patents

Abstract

PURPOSE:To make it possible to obtain an output signal without thermal effect by providing a second sensor part which is connected to a first sensor part in series in a parallel pattern at an approximate interval of (1/8).(2n+1)lambda. CONSTITUTION:This device has a first sensor 4a. In the sensor 4a, two magnetoresistance effect elements 3a and 3b are connected in series in a parallel pattern at an approximate interval (1/4).(2n+1)lambda(n=0, + or -1, + or -2,...) with respect to the period l of a repeating magnetic signal which acts on the magnetic elements. The elements have the anisotropic effect of magnetic resistance and have the same magnetism sensitivity direction. A second sensor part 4b is also provided. In the sensor part 4b, two magnetoresistance effect elements 3c and 3d having the same constitution as those of the first sensor part 4a are connected in series in a parallel pattern at an interval of (1/8).(2n+1)lambda with respect to the first sensor 4a. In this constitution, the output signal from the connecting point between the sensor parts 4a and 4b has the period which is 1/4 the period and the frequency of four times. Since the sensor parts 4a and 4b are operated in a thermally differential state, the output which is not affected by heat is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetoelectric transducer, and more particularly, to a magnetoelectric transducer as a detection means for detecting repeated magnetic signals with high accuracy.

(Prior Art) For example, a magnetoelectric conversion device shown in FIG. 7 is known as a magnetoelectric conversion device used to control the rotation of a rotating body such as a motor or a turntable (see Japanese Patent Publication No. 41335/1983).

This figure conceptually shows a magnetoelectric transducer 30 and a magnet strip 31 as a source of repetitive magnetic signals acting on the magnetoelectric transducer 30.

The magnetoelectric transducer 30 has a first magnetoelectric transducer having an anisotropic effect of magnetoresistance. Second magnetoresistive element 32a.

32b, the magnetic sensing direction of both is the same, and the magnetic strip 31
The N and S magnetic poles are arranged parallel to each other at an interval of λ/4 (period λ), and the first . Second magnetoresistive element 32
a and 32b are connected in series, and the terminal 33 drawn out from the midpoint is used as an output terminal, and each magnetoresistive element 3
The other terminals 34 and 35 of each of 2a and 32b are used as a power supply terminal and a ground terminal.

In this magnetoelectric transducer 30, when the first magnetoresistive element 32a faces the north pole of the magnet strip 31 and a magnetic flux φ from the north pole to the south pole acts on the first magnetoresistive element 32a, the first magnetoresistive element 32a The magnetic field is sensed, and the change in magnetic resistance becomes maximum, and at this time, the second magnetoresistive element 32b is saturated by the horizontal component of the magnetic flux φ, and the change in magnetic resistance becomes minimum.

As a result, the output signal (voltage) vout output from the terminal 33 drawn out from the midpoint of both magnetoresistive elements 32a, 32b is divided by these and becomes the minimum as shown in FIG.

Next, when the magnetic band 31 moves by λ/4 in the direction of the arrow, the first . The states of the second magnetoresistive elements 32a and 32b are opposite to those described above, and at this time, the output voltage yout from the terminal 33 becomes maximum.

Based on such an operation, the output signal yout becomes a sinusoidal wave whose minimum and maximum values are symmetrically inverted every λ/4, so that with respect to the period λ of the magnetic band 31, the output signal yout has a period of 1/2, That is, the output signal vout having twice the frequency can be extracted and used for controlling the rotation of the rotating body.

However, in the case of this magnetoelectric converter 30, it is not possible to obtain an output signal VoutL with a period that is 1/2 of the period λ of the magnet band 31, that is, twice the frequency, and therefore, for example, the rotation speed is relatively low. , and a vi1 stone band 31 is provided on the outer periphery of a rotating body such as a small turntable.
When detecting the rotational state using the electrical conversion device @30, there is a problem in that it is difficult to perform highly accurate position detection and accurate rotation control cannot be performed.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and it is possible to obtain an output signal having a frequency roughly twice that of the conventional example, and also to improve the usage environment. The purpose of this invention is to provide a magnetoelectric conversion device that is not affected by heat.

[Configuration of the Invention (Means for Solving the Problems) The magnetoelectric transducer of the present invention has two magnetoresistive effect elements that have an anisotropic effect of magnetoresistive force and have the same magnetic sensing direction. With respect to the period λ of the repetitive magnetic signal acting on these, the first It has a sensor section and two magnetoresistive elements having the same configuration as the first sensor section, and is arranged in parallel with the first sensor section at an interval of approximately (1/8) (2n+1)λ. and a second sensor section connected in series to the sensor section, and the connection point between both the sensor sections is used as an output terminal.

(for production) The operation of the apparatus having the above configuration will be explained below.

According to this device, a repetitive magnetic signal with a period λ is transmitted to the first .
When acting on the second sensor section, the two magnetoresistive elements of both sensor sections are always configured to detect the magnetic field of one of the magnetoresistive elements every λ/8 due to the magnetic sensing direction and spacing settings described above. The rate of change of resistance is the maximum, and the rate of change of the remaining three magnetoresistive elements is the minimum. As a result, the period of the output signal from the connection point of both sensor sections is 1/4 of the period λ, and the frequency is is four times as large.

Further, since both sensor sections operate in a thermally differential state, the output signal is not affected by heat.

(Example) Examples of the present invention will be described in detail below.

The magnetoelectric transducer @1 shown in FIG. 1 includes two magnetoresistive elements 3a, 3 made of a ferromagnetic material such as nickel cobalt and having an anisotropic effect of magnetoresistive force on the surface of a substrate 2 made of glass or the like.
A first sensor section 4a consisting of a magnetoresistive element 4b, and a second sensor section 4b consisting of two magnetoresistive elements 3c and 3d, which are made of the same material and exhibit the same effect as these two magnetoresistive elements 3a and 3b. They are connected in series, and the end of the magnetoresistive element 3a located on the left side in FIG. As the grounding terminal 6b, the connection point between the magnetoresistive elements 3b and 3c that are adjacent to each other in the center is used as an output terminal 6C from which an output signal is taken out.

Each of the magnetoresistive elements 3a to 3d, the input terminal 6a,
The ground terminal 6b and the output terminal 6C are formed in a parallel arrangement by depositing or etching a ferromagnetic material such as nickel cobalt in the pattern shown in FIG.

Further, the interval between both magnetoresistive elements 3C and 3d is the period λ of a repetitive magnetic signal from the magnetic band 7, which will be described later.
On the other hand, adjacent magnetoresistive elements 3b are formed with an interval of λ/4.

30 are formed with an interval of λ/8.

Furthermore, the magnetic sensing direction of each magnetoresistive element 3a to 3d is indicated by the arrow α1. It is set in the α2 direction.

As shown in FIG. 2, a DC power source 5 having a predetermined voltage E (V) is connected between the input terminal 6a and the ground terminal 6b.

FIG. 2 shows an equivalent circuit of the magnetoelectric converter @1.

Here, the following explanation will be given assuming that Ro is the magnetic resistance when no magnetic flux φ acts on each of the magnetoresistive elements 3a to 3d.

First, with reference to FIG. 5, the strength H(X) of the repetitive magnetic signal (external magnetic field) acting on the magnetoresistive element 3a (or 3b, 3G, 3d) and the magnetic resistance of the magnetoresistive element 3a. The relationship with the rate of change ΔRo/R will be explained.

As mentioned above, the magnetic sensing direction of the magnetoresistive element 3a is indicated by the arrow α1. Since it is set in the α2 direction, the arrow α1. α Magnetic flux φ (1 field strength H(x
)), the rate of change of magnetic resistance ΔRo/Ro becomes maximum, and the value at this time is 21 points shown in FIG.

In this case, the output signal of the magnetoresistive element 3a becomes minimum. This is qualitatively represented by "O".

On the other hand, the magnetoresistive element 3a has an arrow α1 indicating the magnetic sensing direction.
．． When magnetic flux φ acts in a direction perpendicular to α2 direction,
The rate of change ΔR/Ro becomes the minimum, and the value at this time is 22 points or 24 points (HX=±H3: saturation magnetic field strength) shown in FIG. When the maximum magnetic field strength ±HR is larger than the saturation magnetic field strength ±Hs, the value of ΔR/Ro becomes 23 points or 25 points as shown in FIG.

That is, when the magnetic field strength is greater than the saturation magnetic field strength ±Hs, the rate of change in magnetoresistance of the magnetoresistive element 3a is ΔR/
Ro becomes minimum and its output signal takes maximum. This is qualitatively expressed as "1".

The maximum rate of change ΔR/Ro for the R booth is approximately 3%.

The minute change ΔV in the output signal @yout of the magnetoelectric transducer 1 can be expressed by the following equation (1) from the equivalent circuit shown in FIG.

Here, ΔR1 to ΔR4 are each magnetoresistive element 3a.
3d to 3d, respectively.

In other words, the output signal vout is the sum of the output signals of the respective magnetoresistive elements 3a to 3d, and the sum of the output signals of the magnetoresistive elements 3a to 3d.
It is proportional to the ratio of the sum of the output signals of c and 3d.

Next, the operation of the apparatus 1 having the above structure will be explained with reference to FIGS. 3 and 4.

Figure 3 shows the 1. Magnetic band 7 of second sensor section 4a, 4b
FIG. 4 shows its operating state.

In the initial state (time to), the magnetoresistive element 3a of the magnetoelectric transducer 1 receives the magnetic flux φ from the N pole of the magnetic band 7 in the magnetic sensing direction (α2 direction), as shown in FIGS. 3 and 4.
At this time, the rate of change ΔR/Ro becomes maximum, and the output signal qualitatively becomes rOJ. Also,
At this time, the magnetic flux φ from the N pole acts on the magnetoresistive elements 3b and 3G in a direction perpendicular to the magnetic sensing direction, so they are in a state of magnetic saturation and their respective output signals are qualitatively "] ”.

Furthermore, in this state, the magnetic flux φ from another N-pole that is one period apart from the N-pole acts on the magnetoresistive element 3d in a direction perpendicular to the magnetic sensing direction, so the output signal is Qualitatively ``1''.

Therefore, the output signal of the magnetoelectric transducer 1 at this time can be qualitatively expressed as r2/3J, as deduced based on the above equation (1).

Next, time t when the magnetic band 7 is displaced by λ/8 in the -X direction
When the value is 1, based on the above operation, the magnetoresistive elements 3a, 3b and 3d are "1", and the magnetoresistive element 3C
becomes rOJ, and as a result, the output signal vout at this time can be qualitatively expressed as rl/3J.

Furthermore, time t2 when the magnetic band 7 is displaced by λ/8 in the -X direction
When , the magnetoresistive element 3a.

3c and 3d are "1", the magnetoresistive effect element 3b is in the rOJ state, and the output signal ■out at this time is qualitatively r
It can be expressed as 2/3J.

In this way, over the entire range of period λ, the output signal yo
ut changes approximately sinusoidally, taking values of maximum r2/3J and minimum r1/3J every λ/8, and as a result, a signal with a period of 1/4 of the period λ, that is, 4 times the frequency. Become.

As a result, even when the magnetic band 7 is provided around the outer periphery of a turntable that rotates relatively slowly, and the signal for controlling the rotation is extracted by the magneto-electric conversion device @1, it is possible to control the rotation with higher precision than in the conventional example. It becomes possible.

Further, according to the magnetoelectric conversion device 1 described above, the output signal vo
ut connected in series. Second sensor section 4a, 4b
It is taken out from the connection point of both sensor parts 4a and 4b.
Since they operate differentially with respect to heat in the usage environment, changes in the characteristics of both sensor sections 4a and 4b due to heat cancel each other out, and as a result, the output signal yout is not affected by heat.

FIG. 6 shows the other side of the embodiment of the invention.

The magnetoelectric transducer 1A shown in the figure differs from the magnetoelectric transducer 1 in that the second sensor section 4b, which is composed of the magnetoresistive elements 3c and 3d, is shifted by λ/4 toward the magnetoresistive element 3a. This is the point. That is, the magnetoresistive element 3C of this rtt electric conversion I@lA is smaller than the magnetoresistive element 3b by λ/8, -i! -3
The position is shifted to the a side.

This magnetoelectric transducer 1A can also exhibit the same effect as the magnetoelectric transducer 1 described above.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the invention.

[Effects of the Invention] According to the present invention detailed above, first. The second sensor section is arranged in series connection in the above-mentioned magnetic sensing direction and at the above-mentioned interval, and the output signal is taken out from the connection point between the two, so the repeating magnetic signal is four times as large. It is an object of the present invention to provide a magnetoelectric transducer that can obtain an output signal having a frequency of can.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the device of the present invention, FIG. 2 is an equivalent circuit diagram of the device, FIG. 3 is an explanatory diagram showing the arrangement of the device, and FIG. 4 is an explanatory diagram of the operation of the device. FIG. 5 is a characteristic diagram showing the relationship between the external magnetic field strength and the rate of change of magnetoresistance of a magnetoresistive element, FIG. 6 is an explanatory diagram showing the arrangement of another embodiment of the device of the present invention, and FIG. 7 is a conventional diagram. It is an explanatory diagram showing an example arrangement and a waveform of an output signal. 1... Magnetoelectric conversion device, 3a, 3b, 3c, 3d-1ifi resistance effect element, 4
a...first sensor section, 4b...second sensor section. Diagram

Claims (1)

[Claims] Two magnetoresistive elements having an anisotropic magnetoresistive effect and having the same magnetic sensing direction have a period λ of a repetitive magnetic signal acting on them, approximately (1/ 4)・(2n+1)λ(n=O,±1,±2・
A first sensor section connected in series in a parallel arrangement with an interval of ...), and two magnetoresistive elements having the same configuration as the first sensor section, and a second sensor section connected in series in a parallel arrangement with an interval of approximately (1/8).(2n+1)λ, and a connection point between the two sensor sections is used as an output terminal. conversion device.