JP2004226099A - Detection head for magnetic encoder and magnetic encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection head for magnetic encoder that is compact in the widthwise direction, can be attached easily, and has a high versatility, and to provide a magnetic encoder. <P>SOLUTION: The detection head 12 for magnetic encoder contains a belt-like receiver 104 and a transmitter 14 provided on at least one side of the receiver 104 in the widthwise direction. The receiver 104 is set up so as to face a scale having a prescribed measuring locus in almost parallel with the scale. In addition, the transmitter 14 is constituted in a linear body disposed along the side edge of the receiver 104 in the widthwise direction. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnetic encoder used in, for example, industrial equipment and transportation equipment.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a magnetic encoder has been known as a means for detecting a position, a speed, and the like (for example, see Patent Document 1).
[0003]
FIG. 6 is a side view schematically showing an example of the structure of a conventional magnetic encoder, FIG. 7 is a bottom view schematically showing the structure of a detection head of the magnetic encoder, and FIG. FIG. 3 is a plan view schematically showing the structure of the scale of FIG.
[0004]
The magnetic encoder 100 has a detection head 108 including a substantially belt-shaped receiver 104 and transmitters 106 disposed on both sides of the receiver 104 in the width direction.
[0005]
The detection head 108 is disposed so that the receiver 104 faces the scale 102 of a predetermined measurement trajectory substantially in parallel.
[0006]
The scale 102 is an elongated rectangular plate-like body, and a plurality of scale segments 110 are juxtaposed on one surface at an equal pitch P along the measurement trajectory.
[0007]
The scale segment 110 has a configuration in which a plurality of first scale coils 112 and a plurality of second scale coils 114 are arranged side by side along the longitudinal direction on one surface of the scale 102.
[0008]
The first scale coil 112 is an annular body in which a rectangular return portion 112A and a reception portion 112B are formed so as to form a loop via a connection portion 112C, and the return portion 112A is located near the center of the scale 102 in the width direction. A plurality of the receiving units 112B are arranged at equal pitches along the side end of the scale 102 in the width direction.
[0009]
The second scale coil 114 is also an annular body having the same shape as the first scale coil 112, and the return portion 114A is located near the center in the width direction of the scale 102, and has the same shape as the return portion 112A of the first scale coil 112. They are arranged at the same pitch so that they are arranged every other. The receiving section 114 of the second scale coil 114 is arranged along the other end in the width direction of the scale 102, that is, along the side end of the first scale coil 112 opposite to the side on which the receiving section 112B is arranged. Is established.
[0010]
The receiver 104 includes a first reception coil 116 and a second reception coil 118. Each of the first receiving coil 116 and the second receiving coil 118 is formed by bending a wire so as to form a twisted pair, and loops having different winding directions are continuously formed at an equal pitch P every other along the measurement track. Have been to be. Note that the first receiving coil 116 and the second receiving coil 118 are arranged such that the center of each loop is shifted by half the pitch P.
[0011]
Further, the first receiving coil 116 and the second receiving coil 118 are connected to a receiver 120 so that terminal voltages can be individually detected.
[0012]
The transmitting body 106 is obtained by bending a wire rod, and has a rectangular annular first transmitting coil 106A along one side end in the width direction of the receiving body 104 and the same as the first transmitting coil 106A along the other side end in the width direction of the receiving body 104. And the second transmission coil 106 </ b> B having a rectangular ring shape are configured to form one loop. The transmitting body 106 is configured such that the first transmitting coil 106A and the second transmitting coil 106B transmit magnetic fluxes of opposite directions to the scale 102.
[0013]
Since the first transmission coil 106A and the second transmission coil 106B are rectangular annular bodies, current flows in opposite directions along the measurement trajectory on opposite sides in the longitudinal direction.
[0014]
When a current having a predetermined frequency is applied from the transmitter 122 to the transmitter 106, the first transmission coil 106A and the second transmission coil 106B transmit magnetic flux to the scale 102, and these magnetic fluxes The receiver 112B penetrates the receiver 114B of the second scale coil 114. Note that the direction of the magnetic flux passing through the receiving unit 112B is opposite to the direction of the magnetic flux passing through the receiving unit 114B (opposite phase). As a result, an induced electromotive force is generated in the first scale coil 112 and the second scale coil 114, and a reverse current flows, and the return portions 112A and 114A respectively cause the detection head 108 to transmit the magnetic flux of the opposite direction (opposite phase). Reply.
[0015]
The magnetic flux transmitted by the first transmission coil 106A and the second transmission coil 106B also passes through the first reception coil 116 and the second reception coil 118, but these receivers each constitute a twisted pair. Since the induced electromotive force of the loop is reversed every other direction in the opposite direction, the first receiving coil 116, the second receiving coil 116, and the second No voltage is generated across the receiving coil 118.
[0016]
The magnetic flux returned by the return units 112A and 114A passes through the first receiving coil 116 and the second receiving coil 118 of the detection head 108, and returns to each loop of the first receiving coil 116 and the second receiving coil 118. An induced electromotive force is generated according to the magnitude of the applied magnetic flux. As a result, the balance of the induced electromotive force of each loop of the first receiving coil 116 and the second receiving coil 118 is lost, and the receiver 120 reduces the terminal voltage of the first receiving coil 116 and the second receiving coil 118. Detect individually.
[0017]
When the detection head 108 moves along the scale 102, the terminal voltages of the first receiving coil 116 and the second receiving coil 118 change. When the relationship between the amount of movement and the voltage is represented in an orthogonal graph, the shape becomes like a sine wave. Similarly, a voltage corresponding to the amount of movement is generated at both ends of the second receiving coil 118, but the phase is shifted with respect to the voltage at both ends of the first receiving coil 116. The amount of movement of the detection head 108 with respect to the scale 102 can be detected based on the voltage between both ends of the first reception coil 116 and the second reception coil 118.
[0018]
Such a magnetic encoder can be applied to various uses, and it is desirable that the magnetic encoder be compact in order to be attached to various devices.
[0019]
[Patent Document 1]
JP-A-10-31881
[Problems to be solved by the invention]
However, the detection head 108 has a configuration in which the first transmission coil 106 </ b> A and the second transmission coil 106 </ b> B having a rectangular ring shape are arranged side by side on both sides in the width direction of the band-shaped receiver 104, and the size in the width direction is large. was there.
[0021]
The present invention has been made in view of the above problems, and has as its object to provide a magnetic encoder detection head and a magnetic encoder that are compact in the width direction, easy to attach, and highly versatile. .
[0022]
[Means for Solving the Problems]
The present invention includes a substantially strip-shaped receiver, and a transmitter disposed on at least one side in the width direction of the receiver, wherein the receiver is substantially parallel to a scale of a predetermined measurement trajectory. In a detection head of a magnetic encoder disposed so as to face the above, the above-mentioned problem is solved by making the transmitting body a linear body along a lateral end of the receiving body.
[0023]
Note that the transmitter may be disposed on both sides in the width direction of the receiver.
[0024]
Further, a plurality of the transmitters may be arranged in parallel on at least one side in the width direction of the receiver.
[0025]
When a plurality of transmitters are provided, it is preferable to supply a current in the same direction along the measurement track.
[0026]
According to another aspect of the present invention, there is provided a magnetic encoder including the above-described detection head and a scale.
[0027]
Note that the transmitter is disposed on both sides in the width direction of the receiver, and the scale has a rectangular receiving section along one side end in the width direction, and from the receiving section to the other side in the width direction. A plurality of scale coils forming a T-shaped loop that are directly connected to the projecting rectangular return portion are arranged at equal pitches along the measurement trajectory, and alternately in a posture symmetrical in the width direction. They may be juxtaposed.
[0028]
According to the present invention, a magnetic encoder that is compact in the width direction can be realized.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0030]
FIG. 1 is a side view schematically illustrating the entire structure of a magnetic encoder according to the present embodiment, FIG. 2 is a perspective view schematically illustrating the structure of a detection head of the magnetic encoder, and FIG. FIG. 3 is a plan view schematically showing the structure of the scale of FIG.
[0031]
The magnetic encoder 10 is characterized in that the transmitter 14 of the detection head 12 is a linear linear body along the widthwise side end of the receiver 104.
[0032]
Other configurations are the same as those of the conventional magnetic encoder 100, and therefore, the same reference numerals as in FIGS.
[0033]
The transmitters 14 are disposed one by one on both sides in the width direction of the receiver 104, and are connected to the transmitter 122 via the leads 18 extending on the side away from the scale 20. A current in the same direction along the measurement track is supplied to these transmitters 14 so as to transmit a magnetic flux in the opposite direction (opposite phase) to the scale 20.
[0034]
On the surface of the scale 20 facing the detection head 12, a plurality of first scale coils 22 and a plurality of second scale coils 24 forming a T-shaped loop are provided along the measurement trajectory. At every other pitch, they are arranged at the same pitch P so as to be symmetrical in the width direction.
[0035]
The first scale coil 22 is configured such that a rectangular receiving portion 22B along one side end in the width direction and a rectangular return portion 22A protruding from the receiving portion 22B to the other side in the width direction are directly connected. The T-shaped loop is formed.
[0036]
The second scale coil 24 also has the same shape as the first scale coil 22, and the return portion 24A is disposed so as to be arranged alternately with the return portion 22A of the first scale coil 22 near the center of the scale 20 in the width direction. Have been. The receiving portion 24B of the second scale coil 24 extends along the other end in the width direction of the scale 20, that is, along the side end of the first scale coil 22 opposite to the side on which the receiving portion 22B is arranged. It is arranged.
[0037]
Next, the operation of the magnetic encoder 10 will be described.
[0038]
First, when a current having a predetermined frequency is applied from the transmitter 122 of the detection head 12 to the pair of transmitters 14, the transmitter 14 transmits a magnetic flux to the scale 20, and the magnetic flux is received by the first scale coil 22. The section 22B penetrates the receiving section 24B of the second scale coil 24. Note that the transmitter 122 transmits the current in the same direction along the measurement trajectory to the pair of transmitters 14 so that the direction of the magnetic flux passing through the receiving unit 22B and the direction of the magnetic flux passing through the receiving unit 24B are opposite (opposite phase). Turn on electricity.
[0039]
Here, since the transmitting body 14 is a linear body, if the magnitudes of the currents are equal, the magnetic flux to be transmitted is weaker than that of the conventional rectangular first and second transmitting coils 106A and 106B. Become.
[0040]
On the other hand, since the transmitter 14 is a linear body, the self-inductance is smaller than that of the conventional rectangular first and second transmission coils 106A and 106B, so that a larger current can be supplied. . That is, by making the current flowing through the transmitter 14 by the transmitter 122 larger than the current flowing through the first transmission coil 106A and the second transmission coil 106B, the first transmission coil 106A, the magnetic flux equivalent to that of the second transmission coil 106B can be transmitted.
[0041]
Due to the magnetic flux transmitted by the pair of transmitters 14, an induced electromotive force is generated in the first scale coil 22 and the second scale coil 24, and a reverse current flows, and the return portions 22A and 24A respectively transmit the detection head 12 to the detection head 12. A magnetic flux in the opposite direction is returned.
[0042]
The magnetic flux transmitted by the transmitter 14 also penetrates the first receiving coil 116 and the second receiving coil 118. However, since the first receiving coil 116 and the second receiving coil 118 form a twisted pair, No voltage is generated across the first receiving coil 116 and the second receiving coil 118 due to the magnetic flux generated by the transmitter 14.
[0043]
The magnetic flux returned by the return units 22A and 24A passes through the first reception coil 116 and the second reception coil 118 of the detection head 12. Induced electromotive force is generated in each loop of the first receiving coil 116 and the second receiving coil 118 according to the magnitude of the returned magnetic flux. As a result, the balance of the induced electromotive force of each loop of the first receiving coil 116 and the second receiving coil 118 is lost, and the receiver 120 reduces the terminal voltage of the first receiving coil 116 and the second receiving coil 118. Detect individually.
[0044]
When the detection head 12 moves along the scale 20, the terminal voltages of the first receiving coil 116 and the second receiving coil 118 change. For example, when the center of each loop of the first receiving coil 116 and the center of the return portion 22A of the first scale coil 22 are close to each other, every other loop of the first receiving coil 116 has an opposite magnetic flux. However, since every other loop is reversely wound, a voltage in the same direction is generated in each loop, and a maximum voltage is generated in the first receiving coil 116.
[0045]
When the detection head 12 moves by the pitch P with respect to the scale 16, a maximum voltage in the opposite direction is generated in the first receiving coil 116. When the detection head 12 moves along the scale 20 in this manner, a voltage corresponding to the amount of movement is generated at both ends of the first receiving coil 116. When the relationship between the amount of movement and the voltage is represented in an orthogonal graph, the shape becomes like a sine wave.
[0046]
Similarly, a voltage corresponding to the amount of movement is generated at both ends of the second receiving coil 118, but the phase is shifted with respect to the voltage at both ends of the first receiving coil 116.
[0047]
The amount of movement of the detection head 12 with respect to the scale 20 can be detected based on the voltage between both ends of the first reception coil 116 and the second reception coil 118.
[0048]
As described above, the magnetic encoder 10 can surely detect the position and the like as in the related art, and the detection head 12 is a linear body in which the transmitting body 14 is along the receiving body 104. It is more compact in the width direction than a conventional detection head having a rectangular annular transmission coil.
[0049]
Also, the scale 20 has a configuration in which the first scale coil 22 and the second scale coil 24 are arranged corresponding to the receiver 104 and the transmitter 14 of the detection head 12, so that the scale 20 is compact in the width direction. .
[0050]
Further, both the first scale coil 22 and the second scale coil 24 are configured so that the return portions 22A and 24A and the reception portions 22B and 24B are directly connected to form a substantially T-shape, and the wiring density is high. This configuration also contributes to downsizing in the width direction.
[0051]
That is, the magnetic encoder 10 is compact in the width direction as a whole, is easily mounted, can be applied to many devices and the like, and has high versatility.
[0052]
In addition, since the magnetic encoder 10 has a small self-inductance of the transmitting body 14, a large current can be applied to the transmitting body 14 to obtain a strong magnetic flux, and the position and the like can be reliably detected and the reliability is high.
[0053]
In the present embodiment, the scale 20 includes the first scale coil 22 and the second scale coil 24. However, the present invention is not limited to this, and the shape and arrangement of the scale coil are not particularly limited. The present invention is not limited thereto. For example, the present invention can be applied to a scale having a configuration in which a single type of coil is juxtaposed at equal pitches near the center of the scale. In this case, since it is not necessary to transmit the magnetic flux of the opposite phase from the detection head to the scale, the transmitter may be provided only on one side in the width direction of the receiver.
[0054]
Also, the present invention is applicable to a scale having a configuration in which scale segments of a conductor such as a metal piece are arranged side by side at an equal pitch in place of the scale coil.
[0055]
In the present embodiment, the transmitter 14 and the receiver 104 are connected to separate receivers 120 and 122, respectively. However, the present invention is not limited to this. May be integrated into a transceiver, and the transmitter 14 and the receiver 104 may be connected to the transceiver.
[0056]
In the present embodiment, the measurement trajectory of the magnetic encoder 10 is linear, and the transmitter 14 is also a linear linear body. However, the present invention is not limited to this. The present invention is also applicable to a magnetic encoder having a measurement track of another shape such as a circle. In this case, the transmitting body may be a linear body having another shape such as an arc shape along the measurement track.
[0057]
In the present embodiment, the lead portion 18 extends on the side of the transmitter 14 away from the scale 20, but the present invention is not limited to this, and interference between the lead portion and the scale 20 may occur. If there is no problem, for example, the lead portion may extend on one side or both sides in the width direction of the scale 20. By doing so, the magnetic encoder can be made compact also in the thickness direction of the receiver.
[0058]
In order to reduce the self-inductance of the transmitter and the lead, it is preferable to arrange the leads so that the leads and the transmitter or the leads do not approach each other.
[0059]
In the present embodiment, the detection head 12 forms a two-phase detection head including the first reception coil 116 and the second reception coil 118, but the present invention is not limited to this. The present invention is also applicable to a detection head of a single-phase system having a single receiver, a three-phase system having three receivers, or a multi-phase system having four or more receivers.
[0060]
Further, in the present embodiment, the magnetic encoder 10 is configured so that the detection head 12 moves with respect to the scale 20. However, the present invention is not limited to this, and the scale may be moved relative to the detection head. The present invention is also applicable to a magnetic encoder having a moving configuration.
[0061]
Further, in the present embodiment, a pair of transmitters 14 are provided on both sides in the width direction of the receiver 104 and are individually connected to the transmitter 122 via the lead portions 18 in FIG. 2, respectively. However, the present invention is not limited to this. As shown in FIG. It may be connected so as to be energized and connected to the transmitter 122.
[0062]
Also, in the present embodiment, by utilizing the fact that the self-inductance of the transmitter 14 is small, the current that the transmitter 122 supplies to the transmitter 14 is increased, so that the magnetic flux transmitted from the transmitter 14 to the scale 20 is increased. However, the present invention is not limited to this. For example, as shown in a detection head 30 according to the third embodiment of the present invention shown in FIG. May be provided to increase the magnetic flux.
[0063]
In FIG. 5, the two transmitters 18 arranged on one side in the width direction of the receiver 104 are connected by the lead portion 18 and the two transmitters 18 arranged on the other side in the width direction of the receiver 104. Are also connected to the transmitter 122 individually by the lead portions 18, but all (four in the third embodiment) transmitters 14 are connected as in the second embodiment shown in FIG. Alternatively, the leads may be connected so that currents in the same direction along the measurement trajectory may flow, and then connected to the transmitter. Also, all the transmitters 14 may be individually connected to the transmitter.
[0064]
【The invention's effect】
As described above, according to the present invention, there is provided an excellent effect that it is possible to realize a magnetic encoder that is compact in the width direction and easy to attach and has high versatility.
[Brief description of the drawings]
FIG. 1 is a side view schematically showing the structure of a magnetic encoder according to an embodiment of the present invention. FIG. 2 is a perspective view schematically showing the structure of a detection head of the magnetic encoder. FIG. FIG. 4 is an enlarged plan view showing the structure of an encoder scale. FIG. 4 is a perspective view schematically showing the structure of a detection head according to a second embodiment of the present invention. FIG. 5 is a detection diagram according to a third embodiment of the present invention. FIG. 6 is a perspective view schematically showing the structure of a head. FIG. 6 is a side view schematically showing an example of the structure of a conventional magnetic encoder. FIG. 7 is a plan view schematically showing the scale structure of the magnetic encoder. FIG. 8 is a bottom view schematically showing the structure of the detection head of the magnetic encoder.
10, 100 ... magnetic encoders 12, 28, 30, 108 ... detection heads 14, 32, 106 ... transmitters 20, 102 ... scales 22, 24, 112, 114 ... scale coils 22A, 24A, 112A, 114A ... replies Units 22B, 24B, 112B, 114B ... receiving unit 104 ... receiver

Claims (6)

A substantially strip-shaped receiver, and a transmitter disposed on at least one side in the width direction of the receiver, such that the receiver faces substantially parallel to a scale of a predetermined measurement trajectory. In the detection head of the magnetic encoder disposed in
The detecting head of the magnetic encoder, wherein the transmitting body is a linear body along a lateral end of the receiving body. In claim 1,
A detection head for a magnetic encoder, wherein the transmitter is disposed on both sides in the width direction of the receiver. In claim 1 or 2,
A detection head for a magnetic encoder, wherein a plurality of the transmitters are arranged side by side on at least one side in a width direction of the receiver. In claim 2 or 3,
A detection head for a magnetic encoder, wherein currents in the same direction along the measurement track are supplied to the plurality of transmitters. A magnetic encoder comprising: the detection head according to claim 1; and a scale. In claim 5,
The transmitter is disposed on both sides in the width direction of the receiver, and the scale has a rectangular receiver along one side end in the width direction, and projects from the receiver to the other side in the width direction. A plurality of rectangular return portions are directly connected to each other so that scale coils forming a T-shaped loop are arranged at equal pitches along the measurement trajectory and alternately symmetrically in the width direction. A magnetic encoder characterized by being juxtaposed.

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