JPH06180204A - Position detection sensor - Google Patents

Abstract

PURPOSE:To provide a position detection sensor which can detect a position accurately regardless of temperature change etc. CONSTITUTION:The title sensor is provided with two detection means 1 and 2 which are laid out while they are offset each other in position detection direction and in vertical direction by separating them with a specific distance each other in position detection direction and means 3 and 4 to be detected which are laid out opposing the two detection means 1 and 2. Further, it is provided with two detection signal output means 5 and 6 for outputting two detection signals corresponding to the relative position relationship between the two detection means 1 and 2 and the means 3 and 4 to be detected and a coincidence signal output means 7 for outputting a coincidence signal at a position where the difference between two detection signals of the two detection signal output means 5 and 6 is nearly equal to 0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting sensor capable of detecting a position extremely stable even with a change in temperature.

[0002]

2. Description of the Related Art Conventionally, when performing position detection, as shown in FIG. 9, the main part of a position detection sensor using a magnetoresistive element is a plurality of linear parts and a bent part connecting them.
A group of thin film patterns of a ferromagnetic material having a magnetoresistive anisotropic effect such as nickel and cobalt forming a group and another group connected in series with this group are arranged so as to be orthogonal to each other. And a detection head 32 including a magnetoresistive element 30, a bias magnet 31 in which magnetic poles of N pole and S pole for applying a bias magnetic field in the arrangement direction of the magnetoresistive elements 30 are magnetized, and an N pole in the thickness direction, The magnetic pole of the S pole is magnetized, and is constituted by a magnetizing body 33 which moves in the x direction at a distance d from the detection head.

As a result, when the combined magnetic field of the bias magnetic field generated by the bias magnet 31 and the magnetizing body becomes approximately 45 degrees with respect to the magnetoelectric conversion element 30, an output voltage independent of the electric resistance of the magnetoresistive element is obtained. That is, for example,
Since it is known from Japanese Patent Laid-Open No. 6-47528, the position detection signal is obtained at this position.

A conventional position detection sensor using a magnetoelectric conversion element as shown in FIG. 10 moves a magnetizing body 33 with respect to a detection head 32, and an analog output having a waveform shown in FIG. 11 from a detection circuit 34. Get the voltage. The output voltage of the detection circuit 34 is converted to a waveform conversion circuit 3 such as a Schmitt circuit.
5, the waveform is shaped into a rectangular wave, amplified by the amplifier 36, and the relay circuit 37 is operated to obtain the relay circuit output voltage from the output terminal 38.

Further, as shown in FIG. 12, a main part of a position detecting sensor using a magnetic modulation type magnetic sensor is a saturable core 40 having two arms around which coils L1 and L2 are wound. A detection head having two gaps wrapped from both sides by a magnetic yoke 41 and an N pole in the length direction,
The S-pole magnetic pole is magnetized, and is composed of a magnetizing body that moves in the X, Y, and Z directions at a predetermined distance from the detection head.

As shown in FIG. 13, in a position detection sensor using a magnetic modulation type magnetic sensor, an oscillation circuit 44 supplied with a voltage from a power supply circuit 43 applies a high frequency signal to coils L1 and L2 of a detection head 42. Then, the inductances changed in opposite directions are added to the coils L1 and L2 in the detection circuit 45, and a DC voltage proportional to the magnetic flux is output to the output terminal 46.

[0007]

However, the above-described conventional position detecting sensor using a magnetoresistive element is a device and a position detecting sensor using a magnetic modulation type magnetic sensor includes a detection head and a magnetic body due to mechanical causes. The output voltage changes as shown by the dotted line or the one-dot chain line in FIGS. 11 and 14 due to fluctuations in clearance, temperature changes due to changes in the operating environment, fluctuations in drive voltage due to the effects of power supply voltage, etc. There was an inconvenience that the position was misaligned.

The present invention has been made in order to solve these problems, and it is possible to detect a position with high accuracy even with respect to a clearance variation, a temperature variation, a drive voltage variation, and the like. It is intended to provide a sensor.

[0009]

The position detecting sensor of the present invention comprises two detecting means 1, as shown in FIGS. 1 and 3, for example.
2 and the detected means arranged facing the two detecting means 1 and 2 and two detection signals corresponding to the relative positional relationship between the two detecting means 1 and 2 and the detected means. It is composed of two detection signal output means 5 and 6, and a coincidence signal output means 7 which outputs a coincidence signal at a position where the difference between the two detection signals of these two detection signal output means 5 and 6 becomes substantially 0. The position is detected using the coincidence signal.

The position detecting sensor of the present invention, as shown in FIGS. 1 and 2, for example, shows the peak positions of two detection signals corresponding to the relative positional relationship between the two detecting means 1 and 2 and the detected means. It is set so as to be line-symmetric with each other.

Further, in the position detecting sensor of the present invention, as shown in FIG. 1, the detecting means 1 and 2 include a magnetoresistive element made of a ferromagnetic material having an anisotropic effect of magnetoresistance, and a bias to the magnetoresistive element. The detection target means is a magnetized body magnetized in a direction facing the detection means 1 and 2, and a combined magnetic field of the bias magnetic field acting on the magnetoresistive element and the signal magnetic field of the magnetized body. Is to obtain a detection signal at a position of about 45 degrees.

Further, in the position detecting sensor of the present invention, as shown in FIG. 4, the detecting means 10 and 11 each have a core having two arms around which a coil to which a high frequency signal is applied is wound, and the core. On the other hand, it is composed of a yoke which is provided with two gaps and is wrapped from both sides, and the means to be detected 12, 13 are composed of magnetizing bodies 12 and 13 magnetized in the position detecting direction,
The coincidence output signal is obtained at a position where the two detection signals become substantially zero.

[0013]

According to the present invention described above, due to temperature change and the like,
Even if the output voltages of the detection signal output means 5 and 6 vary, the detection is performed at the position where the two detection signals match, so that stable and highly accurate position detection can be performed. Further, according to the present invention, the peak positions of the two detection signals are shifted from each other and set so as to be line-symmetric, so that the positions where the two detection signals match can be easily detected.

Further, according to the present invention, since the detection signal is obtained when the combined magnetic field of the bias magnetic field by the bias magnet and the magnetizing body becomes approximately 45 degrees with respect to the magnetoelectric conversion element,
A stable output can be obtained against temperature changes. Further, according to the present invention, since the detection signal is obtained at the position where the two detection signals become substantially 0, stable and highly accurate position detection can be performed irrespective of changes in temperature and the like.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the position detecting sensor of the present invention will be described in detail below with reference to FIGS. Figure 1
FIG. 1 shows a perspective view of a main part of a position detection sensor using a magnetoresistive element and a front view corresponding thereto. Since the structure of the detection head is the same as the conventional structure shown in detail in FIG. 9, its detailed description is omitted.

In FIG. 1, the detection heads 1 and 2 are arranged so as to be separated from each other by a distance D / 2 in the position detection direction and offset from each other in the direction perpendicular to the detection direction. The magnetic poles of N-pole and S-pole are magnetized in the direction, are separated from each other by the distance D in the position detection direction, and are arranged so as to be offset in the direction perpendicular to the detection direction to obtain a two-track detection path. It was done.

As shown in FIG. 3, a position detecting sensor using a magnetoresistive element is composed of the detecting heads 1 and 2, the magnetic generators 3 and 4 arranged as shown in FIG. 1, and the detecting heads 1 and 2.
With respect to the detection circuit 5 and 6 for detecting the output voltage by the relative movement of the magnetic generators 3 and 4, and the detection circuit 5 and 6
Of the output voltage of the voltage comparison circuit 7, a Schmitt circuit 8 for shaping the coincidence signal of the voltage comparison circuit 7 into a rectangular wave, and an output terminal 9 for outputting the rectangular wave voltage. It is configured.

The position detecting sensor using the magnetoresistive element of this example is constructed as described above, and the detecting circuit 5 is moved by moving the magnetism generating bodies 3 and 4 relative to the detecting heads 1 and 2. The output voltage of 6 and 6 becomes a curve as shown in FIG. Here, A ₁ and B attached to the curves in FIG.
_The points ₁ , ₁ , C ₁ and A ₁ ′, B ₁ ′, C ₁ ′ indicate the positions in the detection direction in FIG. 1, respectively A ₁ , B ₁ , C ₁ and A ₁ ′, B
₁ ', C _1' corresponds to the position of the.

As shown in FIG. 2, the output of one detection circuit 5 is
Peak point A of force voltage₁And the output voltage of the other detection circuit 6
Peak point C₁'Becomes D and the vicinity of the detection position
B₁, B ₁', The output voltage of one detection circuit decreases,
The output voltage of the other detection circuit increases. Well
Also, the intersection B of the curves of the output voltages of the two detection circuits₁,
B₁'Is the peak point A of the output voltage of one detection circuit₁When,
Peak point C of the output voltage of the other detection circuit₁'And the distance D
It will be the midpoint.

Further, when the bias magnetic field by the bias magnets of the detection heads 1 and 2 and the combined magnetic field of the magnetic generators 3 and 4 is 45 degrees with respect to the magnetoresistive element, the electric resistance of the magnetoresistive element causes Can get no output voltage,
For example, since it is known from Japanese Utility Model Publication No. 56-47528, a position detection signal is obtained when the angle becomes approximately 45 degrees. Since the output voltages of the detection circuits 5 and 6 as shown in FIG. 2 can be obtained, the solid line changes from the solid line to the dotted line due to variations in the clearance between the detection heads 1 and 2 and the magnetic generators 3 and 4, temperature variations, or variations in the drive voltage. Even if the output voltage fluctuates, if the position detection point is set at the position of the intersections B ₁ and B ₁ ′ of the curves of the output voltage of the two detection circuits 5 and 6, the fluctuation of the output voltage may occur. Therefore, highly accurate position detection can be performed.

As described above, in FIG. 2, the difference between the two output voltages is 0 at the positions of the intersections B ₁ and B ₁ ′ of the output voltage curves of the two detection circuits 5 and 6, which are the position detection points. However, in FIG. 2, the output voltage from each detection head becomes 0 when the detection head at the right end or the left end is far away from the magnetizer.
Since it may be confused with the position detection point, it is preliminarily displaced so that the difference in the output voltage of each detection head does not become zero.

Further, as shown in FIG. 4, a main part of a position detecting sensor using a magnetic modulation type magnetic sensor is shown. Since the detection head is the same as that shown in detail in FIG. 12,
Detailed description thereof will be omitted. In FIG. 4, the detection heads 10 and 11 are arranged in a row in a vertical direction with respect to the detection direction, and the detection heads 10 and 11 are opposed to the detection heads 10 and 11 with a predetermined distance in the vertical direction to the detection direction. One is magnetized with N-pole and S-pole magnetic poles in the detection direction in one direction, and the other is magnetized with N-pole and S-pole magnetic poles in the detection direction in the other direction. Composed.

A position detection sensor using the magnetic modulation type magnetic sensor shown in FIG. 6 is a detection head 10 and 11, magnetic generators 12 and 13 arranged as shown in FIG. 4, and a power supply circuit 14.
And an oscillator circuit 15 which is supplied with a voltage by a power supply circuit 14 and applies a high frequency pulse voltage to the coils of the detection heads 10 and 11, and a relative movement of the magnetism generators 12 and 13 with respect to the detection heads 10 and 11. , Detection head 10
Of the detection circuits 16 and 17 for adding the inductances of the coils which change in 11 and 11, and the voltage comparison circuit 18 for comparing the output voltages of the detection circuits 16 and 17 and outputting the coincidence signal, and the coincidence of the voltage comparison circuit 18. It is composed of a Schmitt circuit 19 for shaping a signal into a rectangular wave and an output terminal 20 for outputting the rectangular wave voltage.

The position detecting sensor using the magnetic modulation type magnetic sensor of this example is constructed as described above, and by moving the magnetism generating bodies 12 and 13 relative to the detecting heads 10 and 11, The output voltage of the detection circuits 16 and 17 has a curve as shown in FIG. Here, FIG.
A ₂ , B ₂ , C ₂ and A ₂ ′, B ₂ ′, C attached to the inside curve
₂ 'A ₂ indicating the detection direction of the position in Figure 4 have each point of, B _2, C ₂ and _{A 2', B 2 ',} C 2' corresponds to each position of.

As shown in FIG. 5, the positive peak point A ₂ of the output voltage of one detection circuit 16 and the other detection circuit 1
7 is the distance from the positive peak point C ₂ 'of the output voltage and the negative peak point A ₂ ' of the output voltage of one detection circuit 16
And the distance from the negative peak point C ₂ of the output voltage of the other detection circuit 17 corresponds to the length from the N pole to the S pole of the magnetism generators 12 and 13, that is, the length in the detection direction.

Also, in the vicinity of the detection position B ₂ , B ₂ ', the output voltage of one detection circuit 16 decreases and the other detection circuit 1
The output voltage of No. 7 increases. Further, the intersection B ₂ between the curves of the output voltages of the two detection circuits 16 and 17,
B ₂ ′ is the midpoint of the distance between the positive peak point A ₂ of the output voltage of one detection circuit 16 and the positive peak point C ₂ ′ of the output voltage of the other detection circuit 17.

Since the output voltages of the detection circuits 16 and 17 as shown in FIG. 5 can be obtained, the solid lines are changed from the solid lines due to variations in the clearance between the detection heads 10 and 11 and the magnetism generators 12 and 13, temperature variations, or variations in the drive voltage. Even if the output voltage fluctuates as shown by the dotted line, if the position detection point is set at the position of the intersection B ₂ , B ₂ 'of the output voltage curves of the two detection circuits 16 and 17, the output voltage Highly accurate position detection can be performed regardless of fluctuations.

As described above, in FIG. 5, the difference between the two output voltages is 0 at the positions of the intersections B ₂ and B ₂ 'of the output voltage curves of the two detection circuits 16 and 17, which are the position detection points. Is used, but in FIG.
When the detection head at the right end or the left end is far away from the magnetizer, the output voltage from each detection head becomes 0, which may be confused with the position detection point. It is assumed that the voltage difference is displaced so that it does not become zero.

FIG. 7 shows a main part of a position detecting sensor using another magnetoresistive element. In FIG. 7, the detection heads 21 and 22 are arranged so as to be separated from each other by a distance D in the position detection direction and offset from each other in the direction perpendicular to the detection direction, and the magnetic body 23 is arranged in the direction perpendicular to the position detection direction. It has such a length as to cover 22 and is arranged so that the magnetic poles N and S are oriented in the direction of penetrating the paper surface. The position detecting sensor using another magnetoresistive element shown in FIG. 7 is different from the position detecting sensor using the magnetoresistive element shown in FIG. 1 in that one magnetizing body 23 is used. Further, FIG. 7 shows an example in which the detection heads are arranged offset from each other in the detection direction and the vertical direction, but they may be arranged in the vertical direction in a vertical direction without offsetting.

The position detecting sensor using such another magnetoresistive element is equivalent to the position detecting sensor using the magnetoresistive element shown in FIG. 3 with a single magnet. Detailed description of the configuration is omitted. The output voltage of the detection circuit of the position detection sensor using such another magnetoresistive element is as shown in the upper stage when the detection direction is the right direction, as shown in FIG. In the case of the left direction, it becomes as shown in the lower row, and the detection head 2
1 is a waveform A ₃ correspond to, the waveform B ₃ corresponding to the detection head 22.

Here, both in the case of detecting in the right direction shown in the upper stage and in the case of detecting in the left direction shown in the lower stage, the positions are detected at the positions of the intersections of the two waveforms. And the distance D ′ between the intersection of the waveforms of the lower output voltage is the operating range of the position detection sensor, and this distance is equal to the distance D in the position detection direction of the detection heads 21 and 22 shown in FIG. The center position C _{3 of the} magnetizing body corresponds to the midpoint of the distance D ′ between the intersection of the upper output voltage waveform and the lower output voltage waveform.

Even if one magnetic body is constructed in this way, by changing the detection position depending on the detection direction, the clearance between the detection heads 21 and 22 and the magnetic body 23 is changed, the temperature is changed, or the drive voltage is changed. Even if the output voltage fluctuates due to factors such as the above, if the position detection point is set to the position shown in FIG. 8 according to the detection direction, highly accurate position detection can be performed regardless of the fluctuation of the output voltage.

As described above, in FIG. 8, the fact that the difference between the two output voltages becomes 0 at the position of the intersection of the output voltage curves of the two detection circuits, which is the position detection point, is used. In FIG. 8, at the right end or the left end,
When the detection head is far away from the magnet, the output voltage from each detection head becomes 0, which may be confused with the position detection point. Therefore, make sure that the output voltage difference between each detection head does not become 0 in advance. It shall be displaced.

According to this example described above, even if the output voltages of the detection signal output means 5 and 6 change due to temperature changes and the like,
Since the detection is performed at the position where the two detection signals match each other, stable and highly accurate position detection can be performed. Further, according to this example, 2
Since the peak positions of the two detection signals are offset from each other and are set to be line-symmetrical, the positions where the two detection signals match can be easily detected.

Further, according to this example, when the combined magnetic field of the bias magnetic field of the bias magnet and the magnetic generators 3 and 4 becomes about 45 degrees with respect to the magnetoresistive element, the detection signal is obtained, so that the temperature change. A stable output can be obtained. Also,
According to this example, since the detection signal is obtained at the position where the two detection signals become substantially 0, it is possible to stably and irrespective of fluctuations in temperature and the like.
Highly accurate position detection is possible.

Therefore, according to the above-described present example, even if the output voltage fluctuates due to the fluctuation of the clearance between the two detection heads and the one or the two magnetizers, the temperature change, the fluctuation of the driving voltage, etc. If the detection point is set at the position of the intersection of the curves of the output voltages of the two detection circuits,
Highly accurate position detection can be performed regardless of fluctuations in the output voltage. The above-described embodiment is an example of the present invention, and it goes without saying that various other configurations can be adopted without departing from the scope of the present invention.

[0037]

According to the present invention, even if the output voltage of the detection signal output means fluctuates due to temperature change or the like, the detection is performed at the position where the two detection signals match each other, so that stable and highly accurate position detection can be performed. You can Further, since the peak positions of the two detection signals are set so as to be offset from each other so as to be line-symmetrical, it is possible to easily detect the coincident position of the two detection signals, and to detect the movement from both directions in the detection direction. A signal can be generated at the location. Further, since the detection signal is obtained when the combined magnetic field of the bias magnetic field of the bias magnet and the magnetic generators 3 and 4 becomes approximately 45 degrees with respect to the magnetoresistive element, a stable output can be obtained against temperature changes. . Further, since the detection signal is obtained at the position where the two detection signals become substantially 0, stable and highly accurate position detection can be performed irrespective of changes in temperature and the like. Therefore, according to the above-described present invention, even if the output voltage fluctuates due to the fluctuation of the clearance between the two detection heads and the magnetism generator, the temperature change, the fluctuation of the drive voltage, or the like, the position detection point is detected by the two detection circuits. By setting the position of the intersection of the curves of the output voltage, it is possible to perform highly accurate position detection regardless of the fluctuation of the output voltage.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of a position detection sensor using a magnetoresistive element of the present invention.

FIG. 2 is a diagram showing an output voltage of a detection circuit of a position detection sensor using the magnetoresistive element of the present invention.

FIG. 3 is a block diagram of a position detection sensor using the magnetoresistive element of the present invention.

FIG. 4 is a perspective view showing a main part of a position detection sensor using the magnetic modulation type magnetic sensor of the present invention.

FIG. 5 is a diagram showing an output voltage of a detection circuit of a position detection sensor using the magnetic modulation type magnetic sensor of the present invention.

FIG. 6 is a block diagram of a position detection sensor using the magnetic modulation type magnetic sensor of the present invention.

FIG. 7 is a perspective view showing a main part of a position detection sensor using another magnetoresistive element of the present invention.

FIG. 8 is a diagram showing an output voltage of a detection circuit of a position detection sensor using another magnetoresistive element of the present invention.

FIG. 9 is a perspective view showing a main part of a conventional position detection sensor using a magnetoresistive element.

FIG. 10 is a block diagram of a conventional position detection sensor using a magnetoresistive element.

FIG. 11 is a diagram showing output voltages of a detection circuit and a relay circuit of a position detection sensor using a conventional magnetoresistive element.

FIG. 12 is a perspective view showing a main part of a position detection sensor using a conventional magnetic modulation type magnetic sensor.

FIG. 13 is a block diagram of a position detection sensor using a conventional magnetic modulation type magnetic sensor.

FIG. 14 is a diagram showing an output voltage of a detection circuit of a position detection sensor using a conventional magnetic modulation type magnetic sensor.

[Explanation of symbols]

 1, 2 Detection head 3, 4 Magnetization body 5, 6 Detection circuit 7 Voltage comparison circuit 10, 11 Detection head 12, 13 Magnetization body 16, 17 Detection circuit 18 Voltage comparison circuit

Claims (4)

[Claims] 1. A detection means arranged to face the two detection means, and two detection signals corresponding to a relative positional relationship between the two detection means and the detected means. Two detection signal output means for outputting
A position detection sensor which comprises a coincidence signal output means for outputting a coincidence signal at a position where the difference between two detection signals of one detection signal output means becomes substantially 0, and which detects a position using the coincidence signal. 2. The peak positions of the two detection signals corresponding to the relative positional relationship between the two detection means and the detected means are shifted from each other and set so as to be line-symmetrical. 1. The position detection sensor according to 1. 3. The detection means includes a magnetoresistive element made of a ferromagnetic material having an anisotropic effect of magnetoresistance and a bias magnet for applying a bias magnetic field to the magnetoresistive element, and the detected means is the It is composed of a magnetized body magnetized in a direction facing the detection means, and a detection signal is obtained at a position where the combined magnetic field of the bias magnetic field acting on the magnetoresistive element and the signal magnetic field of the magnetized body is approximately 45 degrees. The position detection sensor according to claim 1, wherein: 4. The detection means comprises a core having two arms around which a coil to which a high-frequency signal is applied is wound, and a yoke wrapped around the core with two gaps. 2. The position according to claim 1, wherein the detected means is composed of a magnetized body magnetized in the position detecting direction, and the detection signal is obtained at a position where the two detection signals become substantially zero. Detection sensor.