JP2015172539A - Inductive detection type rotary encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a downsized inductive detection type rotary encoder.SOLUTION: An inductive detection type rotary encoder includes: a stator; a rotor; a first transmission coil and a second transmission coil formed at an inner peripheral side of the first transmission coil; first and second reception coils arranged on the same circumference; and first and second magnetic flux coupling bodies. The first reception coil and the first magnetic flux coupling body form a first track having a first pitch, and the second reception coil and the second magnetic flux coupling body form a second track having a second pitch differing from the first pitch. The first reception coil is divided and disposed on a circumference, and the second reception coil is divided and disposed on the same surface as a surface in that the first reception coil is disposed such that the second reception coil does overlap with the first reception coil in a lamination direction.

Description

  The present invention relates to an inductive detection type rotary encoder that measures the rotation angle of an object using magnetic flux coupling between wirings provided on a rotor and a stator.

  The rotary encoder includes a stator in which a transmission winding and a reception winding are arranged, and a rotor in which a magnetic flux coupling body capable of magnetic flux coupling is arranged (see Patent Document 1). When a rotary encoder is applied to a hand tool such as a micrometer, it is necessary to aggregate a plurality of tracks (transmitting winding, receiving winding, and magnetic flux coupling body) that generate signals having different wavelengths and to reduce the outer diameter thereof. .

JP 2006-322927 A

  An object of the present invention is to provide a miniaturized inductive detection type rotary encoder.

  An inductive detection type rotary encoder according to the present invention includes a stator, a rotor that is rotatable about a rotation axis and disposed opposite to the stator, and a first transmission that is annularly formed on the stator about the rotation axis. The second transmission winding formed in an annular shape on the inner peripheral side of the winding and the first transmission winding, and the stator are arranged on the same circumference around the rotation axis along the transmission winding A first receiving winding and a second receiving winding, and a first ring that is formed in an annular shape with a similar radius around the rotation axis of the rotor and is magnetically coupled to the first transmitting winding and the first receiving winding. And a second magnetic flux coupling body that magnetically couples with the second transmission winding and the second reception winding. The first reception winding and the first magnetic flux coupling body form a first track having a shape that periodically changes in the rotation direction of the rotor with a first pitch, and the second reception winding and the first magnetic flux coupling body. The two magnetic flux coupling bodies form a second track having a shape that periodically changes in the rotational direction of the rotor with a second pitch different from the first pitch. The first receiving winding is divided and arranged on the circumference, and the second receiving winding is arranged on the same surface as the surface on which the first receiving winding is arranged. It is divided and arranged so as not to overlap the line and the stacking direction.

  In the inductive detection type rotary encoder according to the present invention, the first and second receiving windings and the first and second magnetic flux coupling bodies have the same radius, respectively, and the first and second receiving coils. Since the windings are arranged on the same surface, an absolute position detection type (hereinafter referred to as ABS type) induction detection type rotary encoder can be configured in a small size. Furthermore, in the inductive detection type rotary encoder according to the present invention, the first reception winding and the second reception winding are arranged on the same circumference on the same surface so as not to overlap each other. Accordingly, in a rotary encoder having a plurality of tracks, such as an ABS type rotary encoder having two tracks, the number of parts of the stator can be reduced and the stator can be downsized.

  Note that the first receiving winding may be configured by arranging a plurality of first units each having a pair of wirings formed in a loop shape with their phases shifted from each other. Similarly, it is conceivable that the second receiving winding is configured by arranging a plurality of second units each having a pair of wirings formed in a loop shape with a phase shift.

  The plurality of first units may correspond to the first pitch and may be arranged with phases different from each other within the range of the first pitch. Similarly, it is conceivable that the plurality of second units correspond to the second pitch and are arranged with phases different from each other within the range of the second pitch. In this case, for example, of the first track or the second track, the first or second unit constituting the track having an even period is arranged at a position 180 degrees away from the rotation angle of the rotor and connected to each other. Is also possible. According to such a configuration, when an eccentricity occurs, it is possible to suitably reduce, for example, an error that occurs in a track having an even period of the first track or the second track.

  It is also possible to arrange the first or second unit constituting the track having an odd period out of the first track or the second track at a position 180 degrees away from the rotation angle of the rotor and to be connected to each other. It is. According to such a configuration, it is possible to suitably reduce an error generated in the second unit when eccentricity occurs.

  Furthermore, if the phase difference between the adjacent first units is made larger than the phase difference between the adjacent second units, it is possible to reduce the noise in the first track and improve the measurement accuracy. On the other hand, if the phase difference between the adjacent second units is made larger than the phase difference between the adjacent first units, the noise in the track having the odd period of the first track or the second track is reduced and malfunction occurs. It is possible to reduce suitably.

  According to the present invention, a miniaturized inductive detection type rotary encoder can be provided.

It is a front view of a digital micrometer carrying an induction detection type rotary encoder concerning a 1st embodiment. 2 is a cross-sectional view of the rotary encoder 11. FIG. It is sectional drawing of the stator 13 and the rotor 15 which concern on the embodiment. It is a top view which shows the 1st magnetic flux coupling body 41a which concerns on the same embodiment. It is a top view which shows the 2nd magnetic flux coupling body 41b which concerns on the same embodiment. 3 is a plan view of the stator 13. FIG. 3 is a plan view showing a wiring layer of the stator 13. FIG. 3 is a plan view showing a wiring layer of the stator 13. FIG. 3 is a plan view showing a wiring layer of the stator 13. FIG. 3 is a plan view showing a wiring layer of the stator 13. FIG. It is a circuit diagram which shows the electric current supply means to the 1st transmission winding 31a and the 2nd transmission winding 31b which concern on the embodiment. It is the schematic which shows the induced current which arises in the 1st, 2nd magnetic flux coupling bodies 41a and 41b by the electric current which flows through the 1st transmission winding 31a which concerns on the embodiment. It is the schematic which shows the induced current which arises in the 1st, 2nd magnetic flux coupling bodies 41a and 41b by the electric current which flows through the 2nd transmission winding 31b which concerns on the embodiment. It is a figure which shows the signal obtained in the 1st and 2nd receiving winding 32a, 32b which concerns on the same embodiment. It is a top view of stator 13 'of the induction | guidance | derivation detection type rotary encoder which concerns on 2nd Embodiment. It is a top view of stator 13 '' of the inductive detection type rotary encoder concerning a 3rd embodiment. It is a top view of stator 13 '' '' of an induction detection type rotary encoder concerning a 4th embodiment. It is a top view which shows stator 13 '' '' 'which concerns on the other structural example.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

[Configuration of Inductive Detection Type Digital Micrometer According to First Embodiment]
With reference to FIG. 1, the configuration of a digital micrometer equipped with the inductive detection type rotary encoder according to the first embodiment of the present invention will be described. FIG. 1 is a front view of a digital micrometer. A thimble 5 is rotatably attached to the frame 3 of the digital micrometer. The spindle 7 serving as a measuring element is rotatably supported inside the frame 3.

  One end side of the spindle 7 protrudes to the outside, and this one end comes into contact with the object to be measured. On the other hand, a feed screw (not shown in FIG. 1) is cut on the other end side of the spindle 7. This feed screw is fitted into a nut in the thimble 5.

  In this configuration, when the thimble 5 is rotated in the forward direction, the spindle 7 moves forward along the axial direction of the spindle 7, and when the thimble 5 is rotated in the reverse direction, the spindle 7 moves backward along the axial direction of the spindle 7. The frame 3 is provided with a liquid crystal display unit 9 capable of displaying the measured value of the digital micrometer.

[Configuration of Inductive Detection Type Rotary Encoder 11 According to the First Embodiment]
Next, the configuration of the inductive detection type rotary encoder 11 according to the first embodiment incorporated in the digital micrometer of FIG. 1 will be described with reference to FIG. FIG. 2 is a cross-sectional view of the inductive detection type rotary encoder 11.

  The inductive detection type rotary encoder 11 includes a stator 13 and a rotor 15 that is rotatable about a spindle 7 (rotating shaft) and disposed opposite to the stator 13. The rotor 15 is fixed to an end face of a cylindrical rotor bush 19. The spindle 7 is inserted into the rotor bush 19. The stator bush 21 is fixed to the frame 3.

  A feed screw 23 is formed on the surface of the spindle 7 to be fitted into a nut disposed inside the thimble 5 of FIG. Further, a key groove 25 is dug on the surface of the spindle 7 along the longitudinal direction of the spindle 7 (that is, the forward and backward direction of the spindle 7). The key groove 25 is fitted with the tip of a pin 27 fixed to the rotor bush 19. When the spindle 7 rotates, the rotational force is transmitted to the rotor bush 19 via the pin 27 and the rotor 15 rotates. In other words, the rotor 15 rotates in conjunction with the rotation of the spindle 7. Since the pin 27 is not fixed to the key groove 25, the rotor 15 can be rotated without moving the rotor 15 together with the spindle 7.

[Laminated structure of stator 13 and rotor 15 according to the first embodiment]
Next, a schematic configuration of the stator 13 and the rotor 15 will be described with reference to FIG. FIG. 3 is a cross-sectional view of the stator 13 and the rotor 15. As shown in FIG. 3, the stator 13 includes stacked insulating layers 33 </ b> A to 33 </ b> D. The stator 13 includes a first transmission winding 31a, a second transmission winding 31b, a first reception winding 32a, and a second reception winding 32b on the insulating layer 33A and the insulating layer 33B on the rotor 15 side. A portion that is magnetically coupled to first and second magnetic flux coupling bodies 41a and 41b described later is provided, and a shield 35 is provided in an intermediate insulating layer 33C. Further, the remaining wiring 32aD and 32bD of the first reception winding 32a and the second reception winding 32b are provided in the insulating layer 33D farthest from the rotor 15 side. A through hole 34 for passing the spindle 7 is formed in the insulating layers 33A to 33D, and the first and second transmission windings 31a and 31b are formed in an annular shape around the through hole 34.

  On the other hand, as shown in FIG. 3, the rotor 15 includes laminated insulating layers 42A and 42B. The rotor 15 includes a first magnetic flux coupling body 41a in the insulating layer 42A, and a second magnetic flux coupling body 41b in the insulating layer 42B. The insulating layers 42A and 42B are formed with through holes 43 through which the spindle 7 passes, and the first magnetic flux coupling body 41a and the second magnetic flux coupling body 41b are formed in an annular shape with the through hole 43 as the center. Has been.

  The first transmission winding 31a and the second transmission winding 31b flow a transmission current whose current direction changes periodically, that is, in a time division manner, and a magnetic field generated thereby is formed in the rotor 15. 1. It gives to the 2nd magnetic flux coupling bodies 41a and 41b. The first and second transmission windings 31a and 31b are provided on the surface of the insulating layer 33A on the rotor 15 side.

  The first and second magnetic flux coupling bodies 41a and 41b generate induced currents based on the magnetic field generated by the transmission current flowing through the transmission windings 31a and 31b, respectively. The first magnetic flux coupling body 41a is provided on the surface of the insulating layer 42A on the stator 13 side. The second magnetic flux coupling body 41b is provided on the surface of the insulating layer 42B on the stator 13 side. The first and second magnetic flux coupling bodies 41a and 41b have the same diameter and are stacked at positions overlapping each other in the stacking direction via the insulating layer 42A.

  The first reception winding 32a has a magnetic flux coupling based on an induced current generated in the first magnetic flux coupling body 41a by the magnetic flux coupling between the first transmission winding 31a and the first magnetic flux coupling body 41a. The induced voltage generated by is detected. The second reception winding 32b has a magnetic flux coupling based on an induced current generated in the second magnetic flux coupling body 41b by the magnetic flux coupling between the second transmission winding 31b and the second magnetic flux coupling body 41b. The induced voltage generated by is detected.

  A part of the first receiving winding 32a is formed on the surface of the insulating layer 33A on the rotor 15 side, and the remaining part of the first receiving winding 32a is formed on the surface of the insulating layer 33B on the rotor 15 side, Both are connected to each other by through holes or vias penetrating the insulating layer 33A. The second reception winding 32b is also formed in the same layer as the first reception winding 32a. A part of the second reception winding 32b is formed on the surface of the 33A on the rotor 15 side, and the second reception winding 32b The remaining portion of the reception winding 32b is formed on the surface of the insulating layer 33B on the rotor 15 side, and the two are connected to each other by a through hole or a via penetrating the insulating layer 33B. The first receiving winding 32a and the second receiving winding 32b are divided and arranged on the same circumference so as not to overlap each other.

  In FIG. 3, the first receiving winding 32a faces the first magnetic flux coupling body 41a. The first magnetic flux coupling body 41a is disposed between the second reception winding 32b and the second magnetic flux coupling body 41b. With this arrangement, the signal intensity received by the first reception winding 32a can be increased. This arrangement is preferable when the reception signal of the first reception winding 32a affects the measurement accuracy.

[Planar shapes of the stator 13 and the rotor 15 according to the first embodiment]
Next, the first transmission winding 31a, the second transmission winding 31b, the first reception winding 32a, the second reception winding 32b, the first magnetic flux coupling body 41a, and the second magnetic flux coupling body 41b. The planar shape will be described.

  First, the shape of the first magnetic flux coupling body 41a will be described with reference to FIG. FIG. 4 is a plan view showing the first magnetic flux coupling body 41a. As shown in FIG. 4, the first magnetic flux coupling body 41a is formed coaxially with the spindle 7, and is formed so as to overlap the first reception winding 32a with a gap. In the first magnetic flux coupling body 41a, a continuous gear-shaped wiring portion that periodically changes in the rotation direction of the rotor 15 with a pitch λ1 and a circular wiring portion inscribed in the gear-shaped wiring portion overlap each other. It has a shaped wiring. More specifically, the first magnetic flux coupling body 41 a alternately includes concave portions 411 a that are recessed in a direction approaching the spindle 7 and convex portions 412 a that protrude in a direction away from the spindle 7. The first magnetic flux coupling body 41a has an annular coupling portion 413a that couples the plurality of concave portions 411a. That is, the plurality of concave portions 411a and the convex portions 412a form a gear-shaped first current path, and the plurality of concave portions 411a and the connecting portion 413a form an annular second current path. In the example shown in FIG. 4, ten units PA1 configured by a combination of a set of concave portions 411a, convex portions 412a, and connecting portions 413a are provided.

  Next, the shape of the second magnetic flux coupling body 41b will be described with reference to FIG. FIG. 5 is a plan view showing the second magnetic flux coupling body 41b. As shown in FIG. 5, the second magnetic flux coupling body 41b is formed coaxially with the spindle 7, and is formed so as to overlap with the first magnetic flux coupling body 41a and the insulating layer 42A in the stacking direction. . In the second magnetic flux coupling body 41b, a continuous gear-shaped wiring portion that periodically changes in the rotation direction of the rotor 15 with a pitch λ2 and a circular wiring portion circumscribing the gear-shaped wiring portion overlap each other. It has a shaped wiring. More specifically, the second magnetic flux coupling body 41 b alternately includes concave portions 411 b that are recessed in a direction approaching the spindle 7 and convex portions 412 b that protrude in a direction away from the spindle 7. Further, the second magnetic flux coupling body 41b has an annular coupling portion 413b that couples the plurality of convex portions 412b. That is, the plurality of convex portions 412b and the connecting portion 413b form an annular third current path, and the plurality of concave portions 411b and the convex portions 412b form a gear-shaped fourth current path. In the example illustrated in FIG. 5, nine units PA <b> 2 configured by combinations of the concave portions 411 b and the convex portions 412 b are provided. That is, the pitch λ1 and the pitch λ2 are finer and the pitch λ2 is rougher. Furthermore, while the number of units PA1 provided in the first magnetic flux coupling body 41a is N, the number of units PA2 provided in the second magnetic flux coupling body 41b is N-1.

  FIG. 6 is a plan view showing the first and second transmission windings 31a and 31b and the first and second reception windings 32a and 32b. As shown in FIG. 6, the first transmission winding 31a is formed coaxially with the spindle 7 and has a substantially circular current path. The second transmission winding 31b is formed coaxially with the spindle 7 and on the inner periphery of the first transmission winding 31a, and has a substantially circular current path.

  As shown in FIG. 6, the first reception winding 32a is formed coaxially with the spindle 7, is the inner periphery of the first transmission winding 31a, and the outer periphery of the second transmission winding 31b. It is formed by being divided into positions. The first reception winding 32a includes reception windings 321a to 323a. The reception windings 321a to 323a have substantially the same configuration and are arranged with different phases in the rotation direction. In the present embodiment, the reception windings 321a to 323a are arranged so as to be shifted by λ1 / 3. The reception winding 321a is configured to flow an induced current through magnetic flux coupling with the first magnetic flux coupling body 41a. That is, each of the reception windings 321a to 323a forms a unit PA3 including a pair of wirings formed in a loop shape (diamond shape) having a rotation direction length corresponding to one unit PA1 of the magnetic flux coupling body 41a. Yes. In consideration of the signal strength, the mounting error between the rotor 15 and the stator 13 and the influence of changes over time, the receiving winding 321a preferably has two or more units PA3. In this embodiment, the unit PA3 is a rotating shaft. Are arranged one by one at positions different from each other by 180 °. Further, when the reception winding 321a includes a plurality of units PA3, the units PA3 are connected to each other so that all the induced currents in each PA3 are strengthened. Connection between the units PA3 is performed by wiring formed in the insulating layer 33D. The unit PA3 is configured by connecting wirings provided in the insulating layers 33A and 33B through through holes or via holes. Further, the portions intersecting each other are arranged vertically via the insulating layer 33A. The first receiving winding 32a can be magnetically coupled to the first magnetic flux coupling winding 41a, and the second receiving winding 32b can be configured to ensure a space in the rotational direction. Other configurations can be employed.

  The second reception winding 32b is configured in substantially the same manner as the first reception winding 32a. That is, as shown in FIG. 6, the second reception winding 32b is formed coaxially with the spindle 7, is the inner circumference of the first transmission winding 31a, and the second transmission winding 31b. And is divided and formed at a position that does not overlap with the first reception winding 32a. The second reception winding 32b includes reception windings 321b to 323b. The reception windings 321b to 323b are configured in substantially the same manner as the reception windings 321a to 323a, and are shifted by λ2 / 3. The unit PA4 comprising a pair of wirings formed in a loop shape (rhombus shape) included in the second receiving winding 32b has a length in the rotation direction corresponding to one unit PA2 of the second magnetic flux coupling winding 41b. Have Therefore, the unit PA4 has a longer length in the rotation direction than the unit PA3.

  3 to 6, the first receiving winding 32a and the first magnetic flux coupling body 41a have the first track having a shape that periodically changes in the rotation direction of the rotor 15 with the pitch λ1. Form. The second receiving winding 32b and the second magnetic flux coupling body 41b form a second track having a shape that periodically changes in the rotation direction of the rotor 15 with a pitch λ2 different from the pitch λ1. In the present embodiment, since the pitch λ1 of the first track is shorter than the pitch λ2 of the second track, the first track affects the measurement accuracy more strongly than the second track. Since the signal intensity of the first track at the pitch λ1 is higher than the signal intensity of the second track, high measurement accuracy can be obtained. In the present embodiment, since the first reception windings 32a and the second reception windings 32b are alternately distributed in the rotation direction of the rotor 15, the encoder efficiently utilizes the space. Can be miniaturized. Furthermore, in this embodiment, the units PA3, which are a pair of wirings formed in a loop shape (rhombus shape), are arranged one by one at positions different by 180 ° with respect to the rotation axis, and these are formed in the insulating layer 33D. It is configured to be connected in common by the connected wiring. Therefore, even when the rotor 15 and the stator 13 are tilted, it is possible to prevent the signal strength from being reduced by being canceled out by the one unit PA3 and the other unit PA3.

  Next, each wiring layer included in the stator 13 will be described. The transmission board 31 and the reception winding 32 according to the present embodiment can be formed of, for example, a multilayer wiring board. Here, an example in which a four-layer resin wiring board is used will be described with reference to FIGS.

  As shown in FIG. 7, on the insulating layer 33A, one of the transmission part of the first transmission winding 31a and a part of the extraction wiring 31aA and one of the transmission part and the extraction wiring of the second transmission winding 31b are provided. The wiring 31bA is a part of the first receiving winding 32a, and the wiring 32bA is a part of the second receiving winding 32b. The wiring 32aA includes a plurality of wirings arranged inside the transmission unit of the wiring 31aA. The plurality of wires are arranged in a spiral radial pattern in which the outer peripheral end is inclined counterclockwise with respect to the inner peripheral end, and are arranged at positions different by 180 ° with respect to the rotation axis of the rotor 15. The wiring 32bA is configured in substantially the same manner as the wiring 32aA, and is disposed at a position that does not overlap with the wiring 32aA.

  As shown in FIG. 8, on the insulating layer 33B, there are a wiring 31aB which is the remaining part of the lead wiring of the first transmission winding 31a and a remaining part of the lead wiring of the second transmission winding 31b. It has a certain wiring 31bB, a wiring 32aB made of a part of the first reception winding 32a and a lead wiring, and a wiring 32bB made of a part of the second reception winding 32b and a lead wiring. Of the wiring 32aB, the part constituting the first reception winding is composed of a plurality of wirings arranged in a part corresponding to the inside of the transmission part of the wiring 31aA. The plurality of wirings are arranged in a spiral radial pattern with the outer end inclined clockwise with respect to the inner end, and are arranged at positions different from each other by 180 ° with respect to the rotation axis of the rotor 15. The wiring 32bB is configured in substantially the same manner as the wiring 32aB, and is arranged at a position that does not overlap with the wiring 32aB. Note that the wiring 32aB is electrically connected to the wiring 32aA through a contact hole formed in the insulating layer 33A and constitutes the wiring of the unit PA3 (FIG. 6). Similarly, the wiring 32bB is also electrically connected to the wiring 32bA through the contact hole formed in the insulating layer 33A, and constitutes the wiring (FIG. 6) of the unit PA4.

  As shown in FIG. 9, the insulating layer 33C includes a magnetic field generated by the first transmission winding 31a and the second transmission winding 31b and the first reception winding 32a on the back surface of the insulating layers 33A and 33B. A magnetic circuit of a magnetic field received by the second receiving winding 32b is formed, and a magnetic shield wiring 35 that functions as a magnetic shield for the insulating layer 33D is formed. The magnetic shield wiring 35 has an annular portion that forms a magnetic circuit for transmission and reception, and a wiring shield portion that shields a lead-out wiring and the like formed in the insulating layer 33D. A plurality of contact holes are formed in the magnetic shield wiring 35.

  As shown in FIG. 10, the insulating layer 33 </ b> D has a wiring 32 a </ i> D composed of a plurality of wirings and lead wirings commonly connecting the units PA <b> 3 arranged at positions different by 180 ° via the contact holes, and also via the contact holes. A wiring 32bD composed of a plurality of wirings commonly connecting the PAs 4 arranged at 180 ° different positions is formed.

  When the stator 13 according to this embodiment is configured in this way, the first reception winding and the second reception winding are arranged on the same circumference on the same surface so as not to overlap each other. . Accordingly, in a rotary encoder having a plurality of tracks, such as an ABS type rotary encoder having two tracks, the number of parts of the stator can be reduced and the stator can be downsized.

  FIG. 11 shows current supply means for supplying current to the first transmission winding 31a and the second transmission winding 31b. One end of each of the first transmission winding 31a and the second transmission winding 31b is grounded, and the other end is connected to the AC power source V via the switch S1. At the time of measurement, a transmission current whose current direction changes periodically is supplied alternately to the first transmission winding 31a and the second transmission winding 31b by switching the switch S1.

[Operation of the inductive detection type rotary encoder 11 according to the first embodiment]
Next, with reference to FIGS. 12 and 13, signals obtained by the first reception winding 32a and the second reception winding 32b will be described. As described above, the first transmission winding 31a and the second transmission winding 31b cause the transmission current whose current direction changes periodically to flow alternately, that is, in a time-division manner, and the current flows through the first transmission winding 31a. When a current is supplied, a signal is received by the first reception winding 32a, and when a current is supplied to the second transmission winding 31b, a signal is received by the second reception winding 32b.

  First, with reference to FIG. 12, the case where an electric current is sent through the first transmission winding 31a will be described. For example, when a current flows clockwise through the first transmission winding 31a, a magnetic field is generated in each current path in the right-handed screw direction. This magnetic field is generated between the first and second magnetic flux coupling bodies 41a and 41b. As a result, current flows counterclockwise through the first and second magnetic flux coupling bodies 41a and 41b.

  In the first magnetic flux coupling body 41a, a current mainly induced in the convex portion 412a becomes large. Therefore, the current induced in the magnetic flux coupling body 41a mainly flows through the gear-shaped first current path formed by the concave portion 411a and the convex portion 412a. As a result, a magnetic field is generated in the concave portion 411a of the first magnetic flux coupling body 41a from the front surface to the back surface of FIG. 12, and in the convex portion 412a, the magnetic field is generated from the back surface to the front surface of the paper surface. A periodic magnetic pattern is formed. These magnetic fields are received by the first receiving winding 32a.

  In the second magnetic flux coupling body 41b, a current is induced in the convex portion 412b and the connecting portion 413b, and the current flows mainly in the annular third current path. The current flowing through the gear-shaped fourth current path including the concave portion 411b and the convex portion 412b has a value of about one tenth of the current flowing through the third current path. Therefore, the magnetic field forming the magnetic pattern having the pitch λ2 generated in the second magnetic flux coupling body 41b is extremely smaller than the magnetic field forming the magnetic pattern having the pitch λ1 generated in the first magnetic flux coupling body 41a. In addition, the first magnetic flux coupling body 41a has a pitch of λ1 × 10 while the second magnetic flux coupling body 41b has a pitch of λ2 × 9. As shown in FIG. 14, the influence of the magnetic field coupled to the first reception winding 32a cancels the influence of the magnetic field from the second magnetic flux coupling body 41b for a total of one round. That is, the induced voltage caused by the second magnetic flux coupling body 41b cancels out in the first receiving winding 32a due to the different pitches λ1 and λ2, and the signal is not detected. That is, the first reception winding 32a can suppress crosstalk from the second magnetic flux coupling body 41b.

  Next, with reference to FIG. 13, the case where a current is passed through the second transmission winding 31b will be described. For example, when a current flows clockwise through the second transmission winding 31b, the first and second magnetic flux coupling bodies 41a and 41b are counterclockwise in the same manner as when a current flows through the first transmission winding 31a. Current flows around.

  In the second magnetic flux coupling body 41b, a large amount of current is induced in the recess 411b. For this reason, an electric current mainly flows through the gear-shaped 4th current path formed from the recessed part 411b and the convex part 412b. As a result, a magnetic field is generated in the concave portion 411b of the second magnetic flux coupling body 41b from the front surface to the back surface of FIG. 13, and in the convex portion 412b, the magnetic field is generated from the back surface to the front surface of the paper surface. A periodic magnetic pattern is formed. These magnetic fields are received by the second receiving winding 32b.

  On the other hand, in the first magnetic flux coupling body 41a, a current is induced in the concave portion 411a and the connecting portion 413a, and the current mainly flows through the annular second current path. Accordingly, the magnetic field forming the magnetic pattern of the pitch λ1 generated in the first magnetic flux coupling body 41a is compared with the magnetic field forming the magnetic pattern of the pitch λ2 generated in the second magnetic flux coupling body 41b as in the above case. And extremely small. Even if a slight magnetic field induces a current in the second receiving winding 32b, the current cancels out due to the phase difference between the first magnetic flux coupling body 41a and the second receiving winding 32b. It is never detected.

  From the above, as shown in FIG. 14, a reception signal that varies depending on the position of the rotor 15 with respect to the stator 13 is obtained from the first reception winding 32 a and the second reception winding 32 b. Since both the received signals are shifted by one turn while the rotor 15 makes one rotation, the absolute position in one rotation can be detected from the two received signals. Note that FIG. 14 shows only signals for one phase, but actually, three-phase received signals shifted by 120 ° are obtained.

  As described above, according to the present embodiment, since the first and second reception windings 32a and 32b are divided and arranged on the same circumference, the outer diameter of the encoder can be reduced. Moreover, there is no crosstalk.

[Second Embodiment]
Next, an inductive detection type rotary encoder according to a second embodiment of the present invention will be described with reference to FIG. FIG. 15 is a plan view showing first and second transmission windings 31a and 31b and first and second reception windings 32a and 32b ′ of an inductive detection type rotary encoder according to the second embodiment of the present invention. It is. In the inductive detection type rotary encoder according to the present embodiment, the configuration of the second reception winding 32b ′ is different from the configuration of the second reception winding 32b according to the first embodiment. That is, as shown in FIG. 15, in the second embodiment, one of the pair of second reception windings 32b ′ is rotated in the rotational direction with respect to the other second reception winding 32b ′. The positions are shifted by λ2 / 2 (20 ° in the present embodiment).

  According to such a configuration, the following effects can be obtained. That is, since the first magnetic flux coupling body 41a has an even number of cycles (10 cycles) in one rotation, the direction of generation of the induction magnetic field at a position different from the rotation angle of the rotor 15 by 180 ° is the same direction. On the other hand, since the second magnetic flux coupling body 41b has an odd period (9 periods) per rotation, the direction of generation of the induction magnetic field at a position 180 ° different from the rotation angle of the rotor 15 is just opposite. . For this reason, when the stator 13 and the rotor 15 are tilted, the first track has some influence on the received signal due to the pair of units PA1 that are 180 degrees apart as described in the first embodiment. It is possible to cancel. On the other hand, in the second track, the influence on the received signal is strengthened by the pair of units PA2 that are 180 degrees apart in rotation angle.

  Therefore, as in the second embodiment, one of the second reception windings 32b ′ is shifted by λ2 / 2 (20 ° in the present embodiment) in the rotational direction with respect to the other. The signal drop in the second track is prevented.

[Third Embodiment]
Next, an inductive detection type rotary encoder according to a third embodiment of the present invention will be described with reference to FIG. In the inductive detection type rotary encoder according to the second embodiment, a signal having the same phase is detected by shifting one of the second reception windings 32b ′ by half a wavelength with respect to the other, and thereby the stator 13 ′. And the influence of the inclination of the rotor 15 was reduced. In the present embodiment, the area occupied by the second reception winding 32b ″ in the stator 13 ″ is increased, and the influence of eccentricity and inclination is reduced by arithmetic processing such as averaging. That is, in the example shown in FIG. 6, the three reception windings 321b to 323b occupying an area corresponding to 40 ° × 2 are arranged by being shifted by λ2 / 3, which corresponds to about 133 °. Occupies an area of minutes. On the other hand, in the example shown in FIG. 16 of the present embodiment, the three receiving windings 321b ″ to 323b ″ that occupy an area corresponding to 40 ° × 2 are shifted by 2λ2 / 3. And occupies an area corresponding to about 187 °.

[Fourth Embodiment]
Next, an inductive detection type rotary encoder according to a fourth embodiment of the present invention will be described with reference to FIG. In the second and third embodiments described above, means for reducing the effect on the signal received in the second track when eccentricity or inclination occurs is examined. However, when the inductive detection type rotary encoder according to the first embodiment is applied to an ABS type rotary encoder, the signal received in the second track is an auxiliary role of the signal received in the first track. If the influence of the eccentricity or inclination on the received signal is suppressed to a certain level, the measurement accuracy is not affected. Therefore, in the present embodiment, the area occupied by the first reception winding 32a ″ in the stator 13 ″ ″ is increased, and the influence of eccentricity and inclination on the signal received in the first track is further increased. This is to reduce the measurement accuracy of the induction detection type rotary encoder. That is, in the example shown in FIG. 6, the three receiving windings 321a to 323a each occupying an area corresponding to 36 ° × 2 are arranged shifted by λ1 / 3, which corresponds to about 120 °. Occupies the area to be. On the other hand, in the example shown in FIG. 17 of the present embodiment, the three receiving windings 321 a ″ to 323 a ″ each occupying an area corresponding to 36 ° × 2 are shifted by 2λ1 / 3. It occupies an area corresponding to about 168 degrees.

[Other embodiments]
Although the embodiments of the invention have been described above, the present invention is not limited to these embodiments, and various modifications and additions can be made without departing from the spirit of the invention. For example, in the first embodiment, the reception winding 321a is configured by arranging two PAs 3 at positions different from each other by 180 ° around the rotation axis of the rotor 15 and connecting them in common. However, the shape of the reception winding 321a is not limited to this, and the number and arrangement of PAs 3 included can be changed as appropriate. For example, when it is not necessary to consider the influence of eccentricity, the first reception winding 32a ″ ″ and the second reception winding 32b ″ ″ are collectively configured as shown in FIG. It is possible. When the stator 13 ″ ″ is configured in this way, it is possible to configure the stator 13 by omitting the insulating layers 33C and 33D and forming two wiring layers on the insulating layers 33A and 33B. It is. As a result, the number of parts can be greatly reduced. Further, in such a case, there is a possibility that noise is generated in the received signal by the lead-out wiring. However, by providing a dummy pattern DP formed almost in the same manner as this lead-out wiring, this noise can be greatly reduced.

  For example, the second receiving winding 32b faces the second magnetic flux coupling body 41b, and the second receiving winding 32b is interposed between the first receiving winding 32a and the first magnetic flux coupling body 41a. And the 2nd magnetic flux coupling body 41b may be arrange | positioned. The second reception winding 32b faces the first magnetic flux coupling body 41a, and the second reception winding 32b and the second magnetic flux coupling body 41b are interposed between the first reception winding 32a and the second magnetic flux coupling body 41b. One magnetic flux coupling body 41a may be arranged. The first reception winding 32a faces the second magnetic flux coupling body 41b. Between the second reception winding 32b and the first magnetic flux coupling body 41a, the first reception winding 32a and the first magnetic flux coupling body 41a are arranged. Two magnetic flux coupling bodies 41b may be arranged.

  DESCRIPTION OF SYMBOLS 3 ... Frame, 5 ... Thimble, 7 ... Spindle, 9 ... Liquid crystal display part, 11 ... Inductive detection type rotary encoder, 13 ... Stator, 15 ... Rotor, 19 ... Rotor bush, 21 ... Stator bush, 23 ... Feed screw, 25 ... Key groove, 27 ... Pin, 31a ... First transmission winding, 31b ... Second transmission winding, 32a ... First reception winding, 32b ... Second reception winding, 33A to 33D ... Insulating layer 41a ... 1st magnetic flux coupling body, 41b ... 2nd magnetic flux coupling body, 42A, 42B ... insulating layer.

Claims (6)

A stator,
A rotor that is rotatable about a rotation axis and disposed opposite the stator;
A first transmission winding formed in an annular shape around the rotation axis in the stator and a second transmission winding formed in an annular shape on the inner peripheral side of the first transmission winding;
A first reception winding and a second reception winding arranged on the same circumference around the rotation axis along the transmission winding in the stator;
A first magnetic flux coupling body formed in an annular shape with the same radius around the rotation axis in the rotor and magnetically coupled with the first transmission winding and the first reception winding, and the second transmission A winding and a second magnetic flux coupling body magnetically coupled to the second receiving winding,
The first reception winding and the first magnetic flux coupling body form a first track having a shape that periodically changes in a rotation direction of the rotor with a first pitch,
The second receiving winding and the second magnetic flux coupling body form a second track having a shape that periodically changes in a rotation direction of the rotor with a second pitch different from the first pitch,
The first receiving winding is divided and arranged on the circumference,
The second reception winding is divided and arranged on the same surface as the first reception winding so as not to overlap with the first reception winding in the stacking direction. An inductive detection type rotary encoder. The first receiving winding is formed by arranging a plurality of first units each composed of a pair of wirings formed in a loop with a phase shifted from each other.
2. The induction detection type rotary encoder according to claim 1, wherein the second reception winding is formed by arranging a plurality of second units each having a pair of wirings formed in a loop shape with a phase shifted from each other. . The plurality of first units are arranged with phases different from each other within the range of the first pitch corresponding to the first pitch,
The plurality of second units correspond to the second pitch and are arranged with phases different from each other within the range of the second pitch.
Of the first track or the second track, the first or second unit constituting a track having an even period is disposed at a position 180 degrees away from the rotation angle of the rotor and connected to each other. The inductive detection type rotary encoder according to claim 2, wherein: Of the first track or the second track, the first or second unit constituting a track having an odd period is half the pitch of the unit from a position 180 degrees away from the rotation angle of the rotor. 4. The induction detection type rotary encoder according to claim 2, wherein the induction detection type rotary encoder is disposed at a position shifted by only a rotational direction and connected to each other. The inductive detection type rotary encoder according to any one of claims 2 to 4, wherein a phase difference between the adjacent first units is larger than a phase difference between the adjacent second units. 5. The inductive detection type rotary encoder according to claim 2, wherein a phase difference between the adjacent second units is larger than a phase difference between the adjacent first units.

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