JP2010271229A - Encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encoder capable of improving reliability in a detecting action. <P>SOLUTION: The encoder includes a rotating section having a magnetic pattern for generating a first magnetic field, a bias magnet section for generating a second magnetic field capable of changing the first magnetic field, and a detecting section arranged at a portion in non-contact with the bias magnet section so as to detect a combined magnetic field between the first magnetic field and the second magnetic field. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an encoder.

  An encoder is known as a device that detects the number of rotations of a rotating body such as a rotating shaft of a motor (Patent Document 1). For example, the encoder is used by being attached to a rotating shaft of a motor. As a specific configuration of the encoder, for example, a configuration for detecting the rotational speed using magnetism is known.

  For example, an encoder having such a configuration rotates a magnet portion on which a predetermined magnetic pattern is formed integrally with a rotating shaft, and reads a change in the magnetic pattern of the magnet portion with a magnetic sensor, thereby The number of rotations can be detected. In some cases, a bias magnet that changes the magnetic field generated by the magnet unit is attached to the magnetic sensor.

JP 2004-20548 A

  However, in a configuration in which a bias magnet is attached to the magnetic sensor, the magnetic sensor may be damaged when the bias magnet is attached, or an error may occur in the position where the bias magnet is attached. There is a case. For this reason, there exists a possibility that the reliability of a detection operation may fall.

  In view of the circumstances as described above, it is an object of the present invention to provide an encoder capable of improving the reliability of detection operation.

  An encoder according to the present invention is provided in a non-contact manner with respect to a rotating unit having a magnetic pattern for generating a first magnetic field, a bias magnet unit for generating a second magnetic field for changing the first magnetic field, and the bias magnet unit. And a detection unit that detects a combined magnetic field of the first magnetic field and the second magnetic field.

  According to the present invention, it is possible to improve the reliability of the detection operation.

1 is a cross-sectional view showing a configuration of an encoder according to a first embodiment of the present invention. The top view which shows the structure of the encoder which concerns on this embodiment. The top view which shows the structure of the encoder which concerns on this embodiment. The figure which shows the structure of a part of encoder based on 2nd Embodiment of this invention. The top view which shows the structure of the encoder which concerns on this embodiment. The figure which shows the structure of a part of encoder based on 3rd Embodiment of this invention.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing the configuration of the encoder EC.
As shown in FIG. 1, the encoder EC is a device that detects the number of rotations of a rotating body such as a motor. The encoder EC has a rotating member R, a magnet member M, a detection mechanism D, and a positioning member P. The encoder EC is integrally provided with a rotating member R and a magnet member M, and is used in a state in which they are arranged to face the detection mechanism D.

  The rotating member R is a part that is fixed to the rotating shaft 40 of the motor MTR that is a rotating body and rotates integrally with the rotating shaft 40. The rotating member R is made of, for example, SUS and is formed in a disk shape. By using a highly rigid material such as SUS as the constituent material of the rotating member R, the rotating member R having excellent deformation resistance and the like is formed. Of course, other materials may be used as the constituent material of the rotating member R. The rotating member R has a mounting portion 20 and a recess 23.

  The attachment portion 20 is provided on the lower surface Rb of the rotating member R. An insertion hole 20a is formed on the lower surface side of the mounting portion 20 in the center portion in plan view. The rotation hole 40 of the motor MTR is inserted into the insertion hole 20a. The attachment portion 20 has a fixing mechanism (not shown) that fixes the rotation shaft 40 and the attachment portion 20 in a state where the rotation shaft 40 is inserted into the insertion hole 20a.

The concave portion 23 is formed on the upper surface Ra side of the mounting portion 20. The magnet member M is accommodated in the recess 23.
In addition, a light reflection pattern 21 is formed along the outer periphery of the rotating member R at the periphery of the rotating member R.

  The magnet member M is a permanent magnet formed in an annular shape along the rotating direction of the rotating member R. The magnet member M is arrange | positioned at the peripheral part of the rotation member R, for example. A predetermined magnetic pattern Ma (see FIG. 2) is formed on the magnet member M.

  For example, as shown in FIG. 2, as the magnetic pattern Ma of the magnet member M, for example, in the half region of the ring as viewed in the axial direction of the rotary shaft 40, the outer peripheral region is magnetized to the N pole, and the inner peripheral side This region is magnetized to the south pole. In the other half region of the ring, the outer peripheral region is magnetized to the S pole, and the inner peripheral region is magnetized to the N pole. Of course, other forms may be adopted as the magnetic pattern Ma.

  The magnet member M is accommodated in the recess 23 of the rotating member R. The magnet member M is fixed to the rotating member R through, for example, an adhesive (not shown). Therefore, the magnet member M is in an integrally formed state with the rotating member R.

  The detection mechanism D is a part that detects the magnetic field generated by the magnet member M. The detection mechanism D has a detection substrate 30 and a magnetic sensor 32. The detection mechanism D includes an optical sensor 31 that irradiates light to the light reflection pattern 21 formed on the rotating member R and detects reflected light.

  The detection substrate 30 is a plate-like member formed in a circular shape in plan view, for example. The detection substrate 30 is fixed to the positioning member P. Therefore, even if the rotating shaft 40 rotates, the relative position between the detection substrate 30 and the motor MTR does not change. For example, the rotating member R and the magnet member M are accommodated in a state of being aligned with the detection substrate 30.

  For example, a pair of magnetic sensors 32 are arranged at positions overlapping the magnet member M when viewed in the axial direction of the rotary shaft 40 (magnetic sensors 32A and 32B). Each of the magnetic sensors 32A and 32B has a magnetoresistive element (not shown). The magnetic sensors 32A and 32B are respectively held on the detection substrate 30.

  The magnetoresistive element has two orthogonal repeating patterns formed by, for example, metal wiring. In the magnetoresistive element, the electric resistance decreases when the direction of the magnetic field is close to the direction perpendicular to the direction of the current flowing in the repetitive pattern. The magnetoresistive element converts the direction of the magnetic field into an electric signal by utilizing the decrease in electric resistance.

  The detection result of the magnetic sensor 32 is transmitted to a control device (not shown) as an electrical signal.

  The positioning member (mold member) P is a part for positioning the motor MTR, the rotating member R, the magnet member M, and the detection mechanism D. The positioning member P has a main body 41, a bias magnet 42, and a shield member 43. FIG. 2 is a view when the positioning member P is viewed from the detection mechanism D side in the rotation axis direction (the shield member 43 is omitted). FIG. 3 is a view when the detection mechanism D is viewed in the same direction as FIG.

  As shown in FIGS. 1-3, the main-body part 41 is arrange | positioned on the motor MTR. The main body 41 has an internal space K that surrounds the rotating member R and the magnet member M. The main body 41 is in a state in which the rotating member R and the magnet member M are accommodated in the internal space K. The rotating member R and the magnet member M are accommodated so as not to contact the main body portion 41. The main body 41 has a recess 41b at the center of the upper surface 41a when viewed in the rotational axis direction. A peripheral portion 41d that surrounds the concave portion 41b in the rotation axis direction view of the main body portion 41 is a portion that supports the detection mechanism D described above. A holding portion 41c that holds the bias magnet 42 is formed at the bottom of the recess 41b. The main body 41 is configured such that the rotation member R and the magnet member M are separated from the detection mechanism D by the bottom of the recess 41b. For this reason, the bottom part of the recessed part 41b among the main-body parts 41 is comprised with the material which can permeate | transmit the light from the optical sensor 31. FIG.

  The bias magnet 42 is a magnet that generates a second magnetic field that changes the first magnetic field generated by the magnet member M. Examples of the material constituting the bias magnet 42 include a rare earth magnet having a large magnetic force such as samarium / cobalt. The bias magnet 42 is held by the holding portion 41 c of the main body portion 41. As described above, the bias magnet 42 is configured to be held at a position away from the magnetic sensor 32, and is provided in a non-contact manner with respect to the magnetic sensor 32.

  For example, two bias magnets 42 are provided so as to correspond to the magnetic sensors 32A and 32B (bias magnet 42A and bias magnet 42B). The bias magnet 42A is disposed at a position overlapping the magnetic sensor 32A when viewed in the rotational axis direction. The bias magnet 42B is disposed at a position overlapping the magnetic sensor 32B when viewed in the direction of the rotation axis. For this reason, the bias magnet 42A and the bias magnet 42B are arranged at positions overlapping the magnetic pattern Ma formed on the magnet member M as viewed in the direction of the rotation axis.

  The upper surface 42f of each bias magnet 42 is flush with the bottom of the recess 41b. Therefore, the upper surface 42 f of the bias magnet 42 is exposed to the recess 41 b of the main body 41. In the present embodiment, a combined magnetic field of the first magnetic field generated by the magnet member M and the second magnetic field generated by the bias magnet 42 is detected by the magnetoresistive element.

  The shield member 43 is formed so as to cover almost the entire upper surface 41a of the main body 41 including the recess 41b. The shield member 43 covers the bias magnet 42 exposed in the recess 41 b of the main body 41. For this reason, the shield member 43 is disposed between the bias magnet 42 and the detection mechanism D. The shield member 43 is made of a material that can transmit light from the optical sensor 31.

  The control device performs processing for obtaining the rotational speed of the rotary shaft 40 based on the outputs from the magnetic sensors 32A and 32B.

Next, the operation of the encoder EC configured as described above will be described.
When the rotating shaft 40 of the motor MTR rotates, the rotating member R and the magnet member M that are integrally attached to the rotating shaft 40 rotate integrally with the rotating shaft 40. About the detection mechanism D and the positioning member P, since it is not connected or contacted with the rotating shaft 40, it will be in a stationary state without rotating.

  When the rotating member R rotates, the light reflection pattern 21 formed on the rotating member R moves in the rotation direction. The above-mentioned optical sensor 31 emits light to the moving light reflection pattern 21 and detects the movement angle of the light reflection pattern 21 by reading the reflected light.

  Further, when the rotating member R rotates, the magnet member M integrally fixed to the rotating member R rotates. Since the positioning member P is in a stationary state, the magnet member M rotates without the positional relationship between the bias magnet 42 and the magnetic sensor 32 provided in the main body 41 of the positioning member P changing. When the magnet member M rotates, the combined magnetic field of the first magnetic field formed by the magnetic pattern Ma of the magnet member M and the second magnetic field formed by the bias magnet 42 changes periodically. The magnetic sensors 32A and 32B detect the number of rotations of the magnet member M (rotating shaft) by detecting the period of change of the combined magnetic field.

  For example, in a configuration in which the bias magnet 42 is attached to the magnetic sensor 32, the magnetic sensor 32 is damaged when the bias magnet 42 is attached, or an error occurs in the attachment position of the bias magnet 42. Sometimes When the above detection operation is performed in this state, the reliability of the detection operation may be reduced.

  On the other hand, according to the present embodiment, since the detection mechanism D is provided in a non-contact manner with respect to the bias magnet 42, it is not necessary to affix the magnetic sensor 32 when the bias magnet 42 is disposed. For this reason, the magnetic sensor 32 is not damaged, and the displacement of the bias magnet 42 can be avoided. Thereby, the reliability of the detection operation can be improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In this embodiment, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified. In the present embodiment, the configuration of the positioning member P and the arrangement of the bias magnet 42 are different from those in the first embodiment, and other configurations are the same as those in the first embodiment. Therefore, in this embodiment, it demonstrates centering on the said difference.

  FIG. 4 is a cross-sectional view showing the configuration of the positioning member P of the encoder EC2 according to this embodiment. FIG. 5 is a diagram illustrating a configuration when the positioning member P is viewed from the detection mechanism D side in the rotation axis direction.

  As shown in FIG. 4, in the encoder EC <b> 2 according to the present embodiment, a holding portion 42 c that holds the bias magnet 42 is formed inside the main body portion 41, and the bias magnet 42 is held inside the main body portion 41. It is configured. In this case, the bias magnet 42 is not exposed on the upper surface 41 a of the main body 41. As shown in FIG. 5, the position of the bias magnet 42 when viewed in the direction of the rotation axis is the same as in the first embodiment.

  As in the present embodiment, the configuration in which the bias magnet 42 is provided in a non-contact manner with respect to the detection mechanism D may be a configuration in which the bias magnet 42 is held inside the main body 41. Even in this case, there is no need to attach the bias magnet 42 to the magnetic sensor 32, and the magnetic sensor 32 is not damaged. Further, since the positional deviation of the bias magnet 42 can be avoided, the reliability of the detection operation can be improved.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In this embodiment, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified. In the present embodiment, the configuration of the positioning member P and the arrangement of the bias magnet 42 are different from those in the first embodiment, and other configurations are the same as those in the first embodiment. Therefore, in this embodiment, it demonstrates centering on the said difference.

  FIG. 6 is a cross-sectional view showing the configuration of the positioning member P of the encoder EC3 according to this embodiment. In the first embodiment and the second embodiment, the rotation member R and the magnet member M and the detection mechanism D are configured to be separated by a part of the main body 41 of the positioning member P. In the embodiment, the rotation member R, the magnet member M, and the detection mechanism D are not separated. For this reason, the rotating member R, the magnet member M, the magnetic sensor 32 and the optical sensor 31 of the detection mechanism D are housed together in the internal space K formed by the recess 41b of the main body 41 and the detection substrate 30. Yes.

  As shown in FIG. 6, in the encoder EC3, a holding portion 43c that holds the bias magnet 42 is formed below the rotating member R (lower side in the Z direction), and the bias magnet 42 is formed from the magnet member M. Are also arranged on the lower side (a configuration in which the magnet member M is arranged between the magnetic sensor 32 and the bias magnet 42). Specifically, the holding portion 43c is formed in a concave shape on the + Z side (the bottom portion of the concave portion 41b) of the portion of the main body portion 41 that contacts the motor MTR.

  As in the present embodiment, the configuration in which the bias magnet 42 is provided in a non-contact manner with respect to the detection mechanism D may be a configuration in which the bias magnet 42 is disposed below the magnet member M. Even in this case, there is no need to attach the bias magnet 42 to the magnetic sensor 32, and the magnetic sensor 32 is not damaged. Further, since the positional deviation of the bias magnet 42 can be avoided, the reliability of the detection operation can be improved.

  In the present embodiment, the bias magnet 42 is arranged so as to be flush with the bottom of the recess 41b of the main body 41, but the present invention is not limited to this. For example, as shown in the second embodiment, the bias magnet 42 may be arranged inside the main body 41.

  In the present embodiment, the main body 41 does not divide the rotation member R, the magnet member M, and the detection mechanism D. However, the present invention is not limited to this. For example, the first embodiment and the second embodiment described above. Similarly to the embodiment, a part of the main body 41 may be used to divide between the two.

The technical scope of the present invention is not limited to the above-described embodiment, and appropriate modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, the configuration in which the upper surface 42f of the bias magnet 42 is flush with the bottom of the recess 41b (for example, the first embodiment), or the bias magnet 42 is held inside the main body 41. The configuration (for example, the second embodiment) is described as an example, but is not limited thereto. For example, the bias magnet 42 may be held on the recess 41b. In this case, it is necessary to arrange the bias magnet 42 and the magnetic sensor 32 of the detection mechanism D so as not to contact each other.

  Further, as described in the first embodiment, the second embodiment, and the like, for example, in the configuration in which the rotation member R and the magnet member M and the detection mechanism D are separated by the main body 41, the rotation member R and the magnet The bias magnet 42 may be attached to the ceiling portion of the internal space K in which the member M is accommodated.

  EC, EC2 ... Encoder R ... Rotating member (rotating part) M ... Magnet member Ma ... Magnetic pattern (pattern) D ... Detection mechanism (detecting part) P ... Positioning member 32 (32A, 32B) ... Magnetic sensor 41c ... Holding part 42 (42A, 42B) ... Bias magnet

Claims (11)

A rotating part having a magnetic pattern for generating a first magnetic field;
A bias magnet section for generating a second magnetic field for changing the first magnetic field;
A detection unit that is provided in a non-contact manner with respect to the bias magnet unit and detects a combined magnetic field of the first magnetic field and the second magnetic field;
An encoder comprising: The encoder according to claim 1, wherein the bias magnet unit is held at a position away from the detection unit. The encoder according to claim 1, wherein the bias magnet unit is provided on a positioning member that positions the rotating unit and the detection unit. The encoder according to claim 3, wherein the bias magnet unit is provided inside the positioning member. The encoder according to claim 3, wherein the bias magnet portion is provided on a surface of the positioning member. The encoder according to any one of claims 3 to 5, wherein the positioning member includes a holding portion that holds the bias magnet portion. The encoder according to any one of claims 3 to 6, wherein the positioning member has a shield part between the bias magnet part and the detection part. The encoder according to any one of claims 1 to 7, wherein the bias magnet unit is provided between the rotating unit and the detecting unit. The encoder according to any one of claims 1 to 7, wherein the rotation unit is disposed between the detection unit and the bias magnet unit. The encoder according to any one of claims 1 to 9, wherein the bias magnet unit is provided at a position overlapping the magnetic pattern when viewed in the rotation axis direction of the rotating unit. The encoder according to any one of claims 1 to 10, wherein the bias magnet unit is provided at a position overlapping the detection unit as viewed in the rotation axis direction of the rotation unit.

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