JP2000314603A - Position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the positions of two members in a relation of relative movement. SOLUTION: A first member provided with a magnet and a second member having a plurality of magnetic reluctance elements sensing to the magnetic force of a magnet and relatively moving against the first member are measured to be in specific measuring positions. The device has three magnetic reluctance elements MR1 to MR3 extending mutually in parallel and a magnetic reluctance element MR4 extending almost vertically to them, detects the two members to be the origin positions based on the output signal from the connection ends of the magnetic reluctance elements MR1 and MR2, detects the two members to be in the region to be detected based on the output signal from the connection ends of the magnetic reluctance elements MR3 and MR4 and detects that the two members are in the specific position to be detected based on these detection signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a position detecting technique for detecting a position of a moving member with respect to another member.

[0002]

2. Description of the Related Art In some cases, a reciprocating member is reciprocally mounted on a support member to reciprocate a jig or a work arranged on the reciprocating member. In this case, as a drive source of the reciprocating member, there is a device that utilizes fluid pressure by driving a piston rod connected to the reciprocating member by a pneumatic cylinder or a hydraulic cylinder. Also, a ball screw is screw-coupled to the reciprocating member, and the ball screw is rotationally driven by an electric motor to convert the rotational motion of the ball screw into a linear motion of the reciprocating member. There is a device that uses electric power as a drive source, such as a device that directly drives a device.

When such a reciprocating member is driven, an absolute position which is a reference with respect to the supporting member is detected, and the distance moved is detected by an encoder or the like. The position is detected.

In order to detect the absolute position of the reciprocating member with respect to the support member with high accuracy, conventionally, light is applied to a specific portion of the reciprocating member, and the reflected light is detected by a light receiving element. There is a position detecting device using a sensor.

[0005]

When light is radiated to detect an absolute position, position detection can be performed with high accuracy, but the temperature range is limited to a temperature range in which a predetermined detection accuracy can be maintained. However, when used in an environment exceeding a predetermined temperature range, a predetermined detection accuracy cannot be maintained. Furthermore, when an optical sensor is used, there is a limit in miniaturizing and increasing the density of the optical sensor, and it is difficult to reduce the size of the position detecting device.

[0006] It is an object of the present invention to provide a mobile communication system in which
An object of the present invention is to enable the positions of two members to be detected with high accuracy.

Another object of the present invention is to reduce the size of a position detecting device for detecting the positions of two members.

[0008]

The position detecting device of the present invention has a first member provided with a magnet and a plurality of magnetoresistive elements responsive to the magnetic force of the magnet. A position detecting device for detecting that a second member that moves relatively to the second member has reached a predetermined position to be detected, wherein one end is connected to each other, and the other end is connected to a power supply terminal having a different potential from each other. And a first and second magnetoresistive element extending parallel to each other in a direction perpendicular to the direction of movement of the second member, and one end connected to one power supply terminal. A third magnetoresistive element extending parallel to the second magnetoresistive element, connected in series with the third magnetoresistive element and extending in a direction perpendicular to the third magnetoresistive element, and having the other end connected to the other power supply terminal Connection between a fourth magnetoresistive element and the first and second magnetoresistive elements Origin detection means for detecting that the two members are at the origin positions based on the output signals from the first and second members, and based on the output signals from the connection ends of the third and fourth magnetoresistive elements. Area detection means for detecting that the member is within the detection area, and the first and second members are set to predetermined detection positions based on output signals from the origin detection means and the area detection means. Is detected.

The position detecting device of the present invention has a first member provided with a magnet, and a plurality of magneto-resistive elements responsive to the magnetic force of the magnet, and moves relative to the first member. A position detecting device for detecting that the second member and the second member have reached a predetermined detected position, one end of which is connected to each other, and the other end of which is connected to power supply terminals having different potentials; First and second magnetoresistive elements extending parallel to each other in a direction perpendicular to the direction of movement of the second member;
One end is connected to each other, and the other end is connected to a power supply terminal having a different potential. The first and second power supply terminals extend parallel to each other in a direction perpendicular to the moving direction of the second member. A third and fourth magnetoresistive element shifted in the moving direction with respect to the second magnetoresistive element; and a fifth magnetoresistive element having one end connected to one power supply terminal and extending in parallel with the respective magnetoresistive element. An element, a sixth magnetoresistive element connected in series with the fifth magnetoresistive element and extending along the perpendicular direction, and having the other end connected to the other power supply terminal; First origin detection means for detecting that the two members are at a first origin position based on an output signal from a connection end of the magnetoresistive element, and connection of the third and fourth magnetoresistive elements; Based on the output signal from the end,
A second origin detecting means for detecting that the two members are at a second origin position apart from the first origin position, and an output signal from a connection end of the fifth and sixth magnetoresistive elements. Based on the output signals of the first and second origin detecting means and the area detecting means for detecting that the two members are in the detected area.
And that the second member has reached a predetermined detected position between the two origin positions.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a view showing a linear reciprocating device having a support member 11 and a reciprocating member 12 mounted on the support member 11 so as to be able to reciprocate linearly. Support member 1 as first member
In order to drive the reciprocating member 12 which is the second member along 1, a piston rod driven by a fluid pressure cylinder such as a pneumatic cylinder may be connected to the reciprocating member 12, or a rotary drive by an electric motor The ball screw is screwed to the reciprocating member 12. Also,
The reciprocating device 12 may be driven by using a linear motor as the reciprocating device.

A magnet 13 is provided on the reciprocating member 12 to detect that the reciprocating member 12 has reached a predetermined detection position with respect to the supporting member 11.
Is provided with a position detector 14 composed of a plurality of magnetoresistive elements. However, the magnet 13 may be provided on the support member, and the position detector 14 may be provided on the reciprocating member 12.

FIG. 2 is an enlarged view of the magnet 13 shown in FIG. 1. As the magnet 13, a barium ferrite plastic molded magnet using a flat anisotropic magnet is used. Magnetization is performed by pulse magnetizing a specified position in the manner of multipolar magnetization. In FIG. 2, reference symbol M indicates a magnetized portion.

FIG. 3 is an enlarged view of the position detector 14 shown in FIG. 1 and has four ferromagnetic magnetoresistive elements whose resistance values change in response to the magnetic force of the magnet 13. Each magnetoresistive element is formed by depositing a ferromagnetic thin film on a substrate 15 made of glass, ceramic, or the like.

As shown in FIG. 3, assuming that the direction of movement of the reciprocating member 12 is the direction indicated by the arrow P, the position detector 14 is parallel to each other in a direction substantially perpendicular to the direction of movement P. A first magnetoresistive element MR1 extending linearly;
And a second magnetoresistive element MR2.
1 and MR2 are separated by a predetermined distance D. These magnetoresistive elements MR1 and MR2 are each for detecting the origin, and one ends of the respective magnetoresistive elements are connected to each other by a lead wire. The other end of each element is connected to power terminals having different potentials. That is, the other end of the first magnetoresistive element MR1 is connected to the plus terminal + on the high potential side, and the other end of the second magnetoresistive element MR2 is connected to the minus terminal-on the low potential side.

Between the two magnetoresistive elements MR1 and MR2, there is provided a third magnetoresistive element MR3 extending linearly in parallel with the elements MR3 and MR2.
Is connected to a plus terminal +. This element MR
The fourth magnetoresistive element MR4 connected to the other end of the third element 3 extends linearly in a direction perpendicular to the three elements MR1 to MR3, that is, along the moving direction of the reciprocating member 12,
The other end of the element MR4, which is connected at one end to the element MR3, is connected to the minus terminal-. A central portion in the longitudinal direction of the element MR4 is an extension of the third magnetoresistive element MR3, and these elements MR3 and MR4 are magnetoresistive elements for area detection.

These four magnetoresistive elements form a bridge circuit, and three elements MR1 to MR3 are parallel to each other, and another element MR4 extends in a direction perpendicular to each of the three elements. ing. Third for area detection
Is located at an intermediate position between the two magnetoresistive elements MR1 and MR2 for detecting the origin, and this position is the origin of the reciprocating member 12 with respect to the support member 11, that is, a reference position. . However, the third element MR
Even if 3 is biased to one side of the two elements MR1 and MR2, it is possible to detect an intermediate position between the two elements MR1 and MR2 as the origin.

In FIG. 3, each of the elements MR1 to MR1
Although MR4 is shown by one thick line, it can be set to any thickness according to the required sensitivity, and furthermore, by forming an arbitrary number of elements without forming a linear element. The element may be formed so as to meander in a folded manner.

A connection end connecting the two elements MR1 and MR2 to each other is connected to a sensor output terminal, and the two elements M
A connection end connecting R3 and MR4 to each other is connected to a sensor output terminal.

Each of the elements MR1 to MR4 is shown in FIG.
As shown in (A), the reciprocating member 12 has a BR characteristic in which the resistance changes according to the magnetic force acting on the element.
As a result, the magnetic field of the magnet 13 acts on the elements MR1 and MR2 as shown in FIG. FIG.
In (B), the magnetic field acting on the element MR1 is shown by a solid line, the magnetic field acting on the element MR2 is shown by a broken line,
The magnetic fields used for the two elements MR1 and MR2 act with a time difference corresponding to the deviation distance D since these elements are displaced by the distance D in the moving direction.

FIG. 4C shows elements MR1 and MR2 shown in FIG.
FIG. 6B shows a change in resistance of each of the elements MR1 and MR2 when a magnetic field as shown in FIG. 7B acts, and the resistance changes with a time difference corresponding to the shift distance D. In response to this change, the voltage of the sensor output terminal and the reference voltage
When compared by the P amplifier, as shown by the solid line in FIG. 4D, it is possible to obtain a voltage signal corresponding to the difference between the resistance changes of the two elements MR1 and MR2, that is, the origin signal E.

Similarly, the resistances of the elements MR3 and MR4 change in accordance with the magnetic field.
3 and MR4 are almost perpendicular to each other. When the voltage of the sensor output terminal and the reference voltage are compared by the OP amplifier, as shown by the broken line in FIG. A voltage signal corresponding to the difference in the change in resistance, that is, a region signal F can be obtained.

By comparing the voltage of the area signal F with the threshold value J, a DATA signal can be obtained as shown in FIG. 4 (E). It can be detected that the member 12 is within the range K of the predetermined detection area.

Further, the CLK signal corresponding to the origin position S can be obtained from the position where the polarity of the voltage signal changes based on the origin signal E, and the DATA signal and the CLK signal are sent to the flip-flop circuit. , And an output signal OUT is output. The output signal OUT is output for a predetermined time T from the time when the reciprocating member 12 is at the home position S, and the output signal is sent to a display unit such as an LED indicating the state. The output signal will be sent to a control device for controlling the operation of various devices having the drive device shown in FIG.

The origin signal E may be output before the magnet 13 and the position detector 14 reach a predetermined position with the movement of the reciprocating member 12 due to the influence of the auxiliary magnetic flux generated from the magnet 13. By combining both the origin signal E and the area signal F, the origin position S can be accurately detected by eliminating the influence of the origin signal generated by the sub-magnetic flux. Moreover, by using a magnetoresistive element,
As compared with the case where light is used, desired detection accuracy can be obtained in a wide temperature range from a low temperature environment to a high temperature environment.
In addition, the intelligent sensor including the magnetoresistive element and the peripheral circuit makes it possible to reduce the size of the position detection device.
It is possible to reduce the size of a driving member such as an actuator having a position detecting device.

FIG. 5 is a diagram showing a control circuit for performing position detection by processing signals from the respective elements MR1 to MR4. The positive terminal of the DC power supply 16 is connected to the positive terminal + of the position detector 14. , The negative terminal of the power supply 16 is connected to the negative terminal-.

The sensor output terminal is an OP amplifier AMP1a
, And an origin signal E shown in FIG. 4D is output from the amplifier AMP1a. The output signal from the amplifier AMP1a is converted to an OP amplifier AMP1b
, The position of the point at which the polarity changes can be obtained.
The K signal is output.

On the other hand, the sensor output terminal is an OP amplifier AM
This amplifier AMP is connected to the input terminal of P2a.
The area signal shown in FIG. 4D is output from 2a. The output signal from the amplifier AMP2a is converted to an OP amplifier AMP
2b, a region exceeding the threshold value J can be obtained. From the AMP 2b, a DATA signal indicating that the reciprocating member 12 is within the predetermined range K around the origin position S. Is output.

By inputting the output signals of both amplifiers AMP1b and AMP2b to the flip-flop circuit D-FF, an output signal OUT shown in FIG. 4E is output. When the output signal OUT is output to the LED lighting transistor 17, the LED 18 lights for a predetermined time, and at the same time, the output signal OUTPUT is output from the control transistor 19 to the control device.

In the case shown in FIG. 1, a magnet is provided at one place of the support member 11 and the position where the reciprocating member 12 is detected with respect to the support member 11 is one place. Is also possible.

FIG. 6 is a view showing a linear reciprocating device in a case where a plurality of positions are detected as described above. As shown by reference numerals 1 to 4, the support member 11 has magnetized portions at four positions. And that part is used as a magnet. In this case, for example, when the reciprocating member moves from the left side to the right side in FIG. 6, it can be detected that the reciprocating member has reached each position. Thus, the reciprocating member is accelerated from the movement start point 1 to the acceleration start point 2, moved at a constant speed when passing the point, and reciprocated so as to be decelerated from the deceleration start point 3 to the end point 4. The moving speed of the member can be controlled.

FIG. 7 is a diagram showing a position detecting device according to another embodiment of the present invention.
Is detected with respect to the support member 11 in a predetermined section.

The position detector 14 shown in FIG.
2 has a first magnetoresistive element MR1 and a second magnetoresistive element MR2 extending linearly in parallel with each other in a direction substantially perpendicular to the movement direction P of these elements MR1 and MR2.
Are separated by a predetermined distance D1 and their one ends are connected to each other. Further, on both sides of the moving direction P of the second magnetoresistive element MR2, a third magnetoresistive element MR3 and a fourth magnetoresistive element MR4 extend linearly in parallel with each other, and they are separated by a distance D2. One ends are connected to each other at a distance.

First and second magnetoresistive elements MR1, MR2
Are paired, and the third and fourth magnetoresistive elements MR3, MR4
Are paired to form an element for detecting the origin. The other ends of the elements MR1 and MR3 are connected to a plus terminal +, and the other ends of the elements MR2 and MR4 are connected to a minus terminal-.

Between the two magnetoresistive elements MR3 and MR2, there is provided a fifth magnetoresistive element MR5 extending linearly in parallel with the elements MR5 and MR2.
Is connected to a plus terminal +. This element MR
The sixth magnetoresistive element MR6 connected to the other end of 5 extends linearly along the direction perpendicular to the other elements MR1 to MR5, and the other end is connected to the minus terminal-.
The central part in the longitudinal direction of the element MR6 is the fifth magnetoresistive element M
R5 is an extension of R5.
Reference numeral 6 denotes a magnetoresistive element for detecting an area.

FIG. 8A shows the position detector 14 shown in FIG.
FIG. 8B shows the BR characteristics of the devices MR1 and M2.
FIG. 8C shows a magnetic field acting on R2, and FIG. 8C shows a change in resistance of each of the elements MR1 and MR2, which is similar to FIGS. 4A, 4B, and 4C, respectively.

As shown in FIG. 8D, the elements MR1 and M
An origin signal E1 corresponding to the difference in the change in the resistance of R2 can be obtained, and the origin signal E2 can be obtained in accordance with the difference in the resistance between the other two elements MR3 and MR4.

When the point at which the polarity of the origin signal E1 changes is obtained by the OP amplifier, it corresponds to the first origin position S1, and the inverted output signal from the OP amplifier is shown in FIG.
At OUT1. The point at which the polarity of the origin signal E1 changes by the OP amplifier corresponds to the second origin position S2, and the output signal from the OP amplifier is indicated by OUT2 in FIG. 8 (E).

As in the case shown in FIG. 4, since the fifth and sixth MR elements MR5 and MR6 are substantially perpendicular to each other, the voltage at the sensor output terminal is compared with the reference voltage. A region signal F corresponding to the difference between the changes in the resistances of the two elements MR5 and MR6 is obtained. By comparing the voltage of the area signal F with the threshold value J,
As shown in (E), an output signal OUT3 is obtained.

Based on these OUT1 to OUT3 signals, OU
T1 outputs the inverted output signal and goes LOW, OUT2 and OU
When T3 outputs an output signal and becomes HIGH, it can be detected that the reciprocating member 12 is located in the section L between the two origin positions with respect to the support member 11.

FIG. 9 is a diagram showing a control circuit for performing position detection by processing signals from the respective elements MR1 to MR6. The positive terminal of the DC power supply 16 is connected to the positive terminal + of the position detector 14. , The negative terminal of the power supply 16 is connected to the negative terminal-.

The sensor output terminal is an OP amplifier AMP1a
The amplifier AMP1a outputs an origin signal E1 shown in FIG. 8 (D). The output signal from the amplifier AMP1a is output to the OP amplifier AMP1.
The position of the point at which the polarity changes can be obtained by inputting the value to b, and the inverted output signal OUT1 corresponding to the origin position S1 is output from the AMP 1b.

The sensor output terminal is an OP amplifier AMP2a
The amplifier AMP2a outputs an origin signal E2 shown in FIG. 8D. The output signal from the amplifier AMP2a is output to the OP amplifier AMP2
The position of the point at which the polarity changes can be obtained by inputting the signal to b, and an output signal OUT2 corresponding to the origin position S2 is output from the AMP 1b.

On the other hand, the sensor output terminal is an OP amplifier AM
This amplifier AMP is connected to the input terminal of P3a.
The area signal F shown in FIG. 4D is output from 3a.
The output signal from the amplifier AMP3a is supplied to an OP amplifier AM
By inputting the signal to P3b, an area exceeding the threshold value J can be obtained. From AMP3b, an output signal OUT3 indicating that the reciprocating member 12 is within the predetermined area K around the section L. Is output.

By inputting the output signals of both amplifiers AMP1b and AMP2b to the flip-flop circuit D-FF, an output signal OUT shown in FIG. When the output signal OUT is output to the LED lighting transistor 17, the LED 18 lights for a predetermined time, and at the same time, the output signal OUTPUT is output from the control transistor 19 to the control device.

Each output signal OUT1 to OUT3 is DTL
Transistors 17, 19 via diodes 21 to 23
Output to the base.

The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

For example, in the illustrated embodiment, the position of the reciprocating member 12 in a reciprocating device in which the reciprocating member 12 is moved with respect to the fixed-side support member 11 is detected. However, even when both members move, the present invention can be applied to detect the mutual positions of the two members.

[0049]

According to the present invention, it is possible to detect whether or not a moving member has reached a predetermined position without using light such as laser light. Since the magnetoresistive element for position detection is used, a usable temperature environment can be widened. The size of the position detection device can be reduced.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a linear reciprocating device.

FIG. 2 is a perspective view showing the magnet shown in FIG. 1;

FIG. 3 is a perspective view showing the position detector shown in FIG.

4A is a diagram illustrating a BR characteristic of a magnetoresistive element, FIG. 4B is a diagram illustrating a magnetic field acting on the magnetoresistive device, and FIG. 4C is a diagram illustrating a resistance of the magnetoresistive device. It is a diagram showing a change in the value, (D) is a diagram showing an origin signal and a region signal, (E) is a diagram showing an output signal from the control circuit.

FIG. 5 is a control circuit for processing a signal from the position detector shown in FIG. 3 to perform position detection.

FIG. 6 is a perspective view showing a linear reciprocating device provided with a position detecting device according to another embodiment of the present invention.

FIG. 7 is a perspective view showing another type of position detector.

8A is a diagram illustrating a BR characteristic of a magnetoresistive element, FIG. 8B is a diagram illustrating a magnetic field acting on the magnetoresistive element, and FIG. 8C is a diagram illustrating a resistance of the magnetoresistive element. It is a diagram showing a change in the value, (D) is a diagram showing an origin signal and a region signal, (E) is a diagram showing an output signal from the control circuit.

9 is a control circuit for processing a signal from the position detector shown in FIG. 7 to perform position detection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Support member 12 Reciprocating member 13 Magnet 14 Position detector 15 Substrate 16 Power supply 17, 19 Transistor 18 LED

Claims (2)

[Claims] A first member provided with a magnet; and a plurality of magnetoresistive elements responsive to a magnetic force of the magnet.
A position detection device for detecting that a second member relatively moving with respect to the member has reached a predetermined detected position, one end of which is connected to each other, and the other end of which has a mutual potential. First and second magnetoresistive elements connected to different power supply terminals and extending in parallel with each other in a direction perpendicular to the direction of movement of the second member; one end connected to one power supply terminal; A third magnetoresistive element extending in parallel with the first and second magnetoresistive elements; a third power supply terminal connected in series with the third magnetoresistive element and extending in a direction perpendicular to the other; 4th connected to
A magnetoresistive element; origin detection means for detecting that the two members are at the origin based on an output signal from a connection end of the first and second magnetoresistive elements; Area detection means for detecting that the two members are within the area to be detected, based on an output signal from the connection end of the magnetoresistive element of No. 4, and output signals from the origin detection means and the area detection means A position detecting device for detecting that the first and second members have reached a predetermined detected position based on the detected position. A first member provided with a magnet; and a plurality of magnetoresistive elements responsive to a magnetic force of the magnet.
A position detection device for detecting that a second member relatively moving with respect to the member has reached a predetermined detected position, one end of which is connected to each other, and the other end of which has a mutual potential. First and second magnetoresistive elements connected to different power supply terminals and extending in parallel with each other in a direction perpendicular to the direction of movement of the second member, one ends of which are connected to each other; The ends are connected to power supply terminals having different potentials from each other, extend parallel to each other in a direction perpendicular to the direction of movement of the second member, and extend with respect to the first and second magnetoresistive elements. A third and a fourth magnetoresistive element shifted in the moving direction; a fifth magnetoresistive element having one end connected to one power supply terminal and extending in parallel with each of the magnetoresistive elements;
A sixth magnetoresistive element connected in series with the first magnetoresistive element and extending along the right angle direction, and having the other end connected to the other power supply terminal; and a connection end between the first and second magnetoresistive elements. Origin detection means for detecting that the two members are at the first origin position based on the output signals from the first and second members, and an output signal from the connection end of the third and fourth magnetoresistive elements. A second origin detecting means for detecting that the two members are at a second origin position distant from the first origin position based on the first and second members. Area detection means for detecting that the two members are within the detection area based on an output signal; and based on output signals of the first and second origin detection means and the area detection means, The first and second members are at a predetermined detected position between two origin positions; A position detecting device characterized in that the position is detected.