Encoder and motor equipped with same

Abstract

The present invention prevents damage to a rotating plate. An encoder (20) comprises: a bracket (11); a rotating plate (21) which rotates about an axis of rotation; an optical module (22) which faces the rotating plate (21) and which includes at least one of a light source and a light receiving element; a board (23) to which the optical module (22) is attached; and a frame (24) which is fixed to the bracket (11) and which supports the board (23). The bracket (11) has at least three recessed portions (11a) in a surface facing the frame (24). The frame (24) has at least three projecting portions (24a) which enter the recessed portions (11a) of the bracket (11) with a gap therebetween. In a radial direction of the rotating plate (21), a difference between an internal dimension (D1) of the frame (24) and an external dimension (D2) of the rotating plate (21) is greater than a difference between an internal dimension (D3) of the recessed portions (11a) and an external dimension (D4) of the projecting portions (24a).

Description

[Technical Field]

[0001] The present disclosure relates to an encoder and a motor including the same. [Background technology]

[0002] Conventionally, an encoder that detects the rotational position of a motor shaft is known (for example, see Patent Document 1). The encoder disclosed in Patent Document 1 includes a rotating plate attached to the shaft and provided with a predetermined pattern, and a main body provided with a detector that detects the predetermined pattern. When viewed from the axial direction of the shaft, this main body is fixed to a predetermined object at a fixing position that is arranged symmetrically with respect to an imaginary line connecting the detector and the center of the shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-211347 Summary of the Invention

[0004] However, when fixing the main body to the object, it is necessary to fine-tune the fixing position of the main body to adjust the relative position of the detector with respect to the rotating plate. When making such fine adjustments, the main body and the rotating plate may come into contact with each other, which may cause deformation or damage to the rotating plate. In such a situation, one of the objects of the present disclosure is to prevent damage to the rotating plate.

[0005] A first aspect of the present disclosure relates to an encoder. The encoder includes a bracket, a rotating plate that rotates around a rotation axis, an optical module facing the rotating plate and including at least one of a light source that irradiates light onto the rotating plate and a light-receiving element that receives light irradiated from the light source and reflected by the rotating plate or light that transmits through the rotating plate, a substrate to which the optical module is attached, and a frame fixed to the bracket and supporting the substrate. The bracket has three or more recesses on a surface facing the frame, and the frame has three or more protrusions at positions corresponding to the three or more recesses that fit into the recesses of the bracket via gaps, and the difference between the inner dimension of the frame and the outer dimension of the rotating plate in the radial direction of the rotating plate is greater than the difference between the inner dimension of the recesses and the outer dimension of the protrusions.

[0006] Another second aspect of the present disclosure relates to a motor including the above-mentioned encoder, a shaft penetrating the bracket, a rotor attached to the shaft, a stator facing the rotor, and a case coupled to the bracket and accommodating the rotor and the stator, wherein the rotating plate is attached to the shaft and rotates together with the shaft.

[0007] Another third aspect of the present disclosure relates to an encoder. The encoder includes: a rotating plate that rotates about a rotation axis; an optical module facing the rotating plate and including at least one of a light source that irradiates light onto the rotating plate and a light-receiving element that receives light emitted from the light source and reflected by the rotating plate or light that transmits through the rotating plate; a substrate to which the optical module is attached; and a frame that supports the substrate. The substrate has first, second, and third mounting holes through which screws are inserted to secure the substrate and the frame in a positioned state. The frame has three through holes, each through which the screws are inserted, located at positions corresponding to the first to third mounting holes. The difference between the inner dimension of the frame and the outer dimension of the rotating plate in the radial direction of the rotating plate is greater than the difference between the inner dimensions of the first to third mounting holes and the outer dimension of the screw shanks or the difference between the inner dimensions of the three through holes and the outer dimension of the screw shanks.

[0008] Another fourth aspect of the present disclosure relates to a motor including a bracket, a shaft penetrating the bracket, and the encoder of the third aspect, wherein the rotating plate is attached to the shaft and rotates together with the shaft, and the substrate, together with the frame, is fixed to the bracket with the screws.

[0009] According to the present disclosure, damage to the rotating plate can be prevented. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view schematically showing a motor including an encoder according to a first embodiment. [Figure 2] 3 is a schematic diagram of a substrate as seen from the rotating plate in the motor according to the first embodiment. FIG. [Figure 3] 1 is a schematic view showing a frame of a motor according to a first embodiment as viewed from a case. [Figure 4] 10 is a schematic view of a substrate as seen from the rotating plate in a motor according to a second embodiment. FIG. [Figure 5]2 is a diagram showing the upper surface of the rotating plate of the motor according to the first embodiment as viewed from the substrate. FIG. [Figure 6] 3 is a cross-sectional view schematically showing the relative positions of an optical module, a substrate, and a rotating plate of the motor according to the first embodiment. FIG. [Figure 7] 2 is a plan view showing the arrangement of light sources and light receiving elements of an optical module included in the motor according to the first embodiment. FIG. [Figure 8] 2 is a schematic view showing a bracket of the motor according to the first embodiment as viewed from the board side. FIG. [Figure 9] 4 is a diagram showing the positional relationship between the bracket, the inner peripheral surface of the frame, and the outer peripheral surface of the boss when the bracket is viewed from the board in the motor according to the first embodiment. FIG. [Figure 10] 10 is a cross-sectional view schematically showing the relative positions of an optical module, a substrate, and a rotating plate in a second modification of the motor according to the first embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiments of an encoder and a motor according to the present disclosure will be described below using examples. However, the present disclosure is not limited to the examples described below. While specific numerical values ​​and materials may be used in the following description, other numerical values ​​and materials may be used as long as the effects of the present disclosure are obtained.

[0012] (encoder) An encoder according to an embodiment of the present disclosure (hereinafter also referred to as a first encoder) includes a bracket, a rotating plate, an optical module, a substrate, and a frame.

[0013] The bracket is a member for attaching the first encoder to the case of the motor.

[0014] The rotating plate rotates around a rotation axis. The rotating plate may be attached to the shaft of the motor. The rotating plate may be attached directly or indirectly to the shaft. In the latter case, for example, the rotating plate is fixed to a boss fixed to the shaft. The rotating plate rotates together with the shaft, with the axis of the shaft serving as the rotation axis. The rotating plate has a predetermined pattern formed along its circumferential direction. The predetermined pattern may be a pattern used to detect the rotational position of the shaft, or a pattern used to detect the rotational position and rotation speed of the shaft. Here, the rotational position of the shaft refers to the relative angular position or absolute angular position of the shaft, and the rotation speed of the shaft refers to the number of times the shaft has rotated.

[0015] The optical module has at least one of a light source that irradiates light onto the rotating plate and a light receiving element. The light receiving element receives light that is irradiated from the light source and reflected by the rotating plate (reflected light) or light that passes through the rotating plate (transmitted light). When the light receiving element receives reflected light, both the light source and the light receiving element are arranged on one side of the rotating plate. On the other hand, when the light receiving element receives transmitted light, one of the light source and the light receiving element is arranged on one side of the rotating plate and the other on the other side of the rotating plate. The light receiving element can convert the received light into an electrical signal. This electrical signal can be used to determine the rotational position and rotation speed of the shaft.

[0016] An optical module is attached to the substrate. Various electronic components may be mounted on the substrate. The substrate may be substantially disk-shaped. "Substantially disk-shaped" refers to a plate-like shape in which, for example, 80% or more of the outer edge is formed by an arc.

[0017] The frame accommodates the rotating plate and supports the substrate so that the optical module faces the rotating plate. The frame and the substrate may be fixed to each other by a predetermined fixing means. The frame may be substantially cylindrical. In other words, the frame may have a cylindrical space therein having a diameter larger than that of the rotating plate. The rotation axis of the rotating plate is coaxial with the cylindrical space. The outer diameter of the frame may be equal to or different from the outer diameter of the substrate.

[0018] Here, the bracket has three or more recesses on the surface facing the frame. The three or more recesses may be recessed in a direction along the rotation axis of the rotating plate. The three or more recesses may be arranged concentrically. The three or more recesses may be arranged at equal intervals or at uneven intervals in the circumferential direction of the motor. The recesses may be, for example, circular when viewed in a direction along the rotation axis of the rotating plate, but are not limited to this.

[0019] The frame has three or more protrusions at positions corresponding to the three or more recesses, each of which fits into the recesses of the bracket via a gap. The number of protrusions may be the same as or less than the number of recesses. The three or more protrusions may protrude in a direction along the rotation axis of the rotating plate. Each of the three or more protrusions is arranged to fit into a corresponding recess of the bracket. The protrusions may be, for example, circular when viewed in a direction along the rotation axis of the rotating plate, but are not limited to this.

[0020] In the radial direction of the rotating plate, the difference (hereinafter also referred to as dimensional difference A) between the inner dimension (or inner diameter) of the frame and the outer dimension (or outer diameter) of the rotating plate is greater than the difference (hereinafter also referred to as dimensional difference B) between the inner dimension (or inner diameter if the concave portion is circular) of the bracket's recess and the outer dimension (or outer diameter if the convex portion is circular) of the frame.

[0021] Here, when fine-tuning the relative position of the optical module with respect to the rotating plate, such as during assembly of the first encoder, the position of the substrate or frame on which the optical module is mounted is fine-tuned. During this fine-tuning, because the convex portion of the frame fits into the concave portion of the bracket, the frame (and the substrate and optical module) only moves radially around the rotating plate within a range where the outer surface of the convex portion does not come into contact with the inner surface of the concave portion. Furthermore, because of the relationship between the above-mentioned dimensional difference A and dimensional difference B (i.e., dimensional difference A is larger than dimensional difference B), even if the frame is moved as far as possible within this range, the inner surface of the frame does not come into contact with the outer edge of the rotating plate. Therefore, damage to the rotating plate due to contact with the frame can be prevented during assembly of the first encoder.

[0022] The three or more protrusions on the frame may be arranged at positions that are rotationally asymmetric around the rotation axis of the rotating plate. With this configuration, the relative positions between the frame and the bracket are identified in the circumferential direction of the rotating plate by the protrusions on the frame and the recesses on the bracket. This makes it possible to prevent assembly errors in the first encoder. The three or more protrusions may be arranged at positions that are rotationally symmetric around the rotation axis of the rotating plate. For example, it is conceivable to arrange three protrusions at equal intervals (at 120° intervals) in the circumferential direction of the rotating plate.

[0023] An encoder according to another embodiment of the present disclosure (hereinafter also referred to as a second encoder) includes a rotating plate, an optical module, a substrate, and a frame. The configurations of the rotating plate and the substrate of the second encoder may be the same as those of the first encoder.

[0024] The substrate has a first mounting hole, a second mounting hole, and a third mounting hole through which screws are inserted to fix the substrate and the frame in a positioned state relative to each other. The first to third mounting holes may be arranged at positions that are rotationally asymmetric around the rotation axis of the rotating plate.

[0025] The frame has three through holes provided at positions corresponding to the first to third mounting holes, respectively, and through which the screws are inserted. The centers of the three through holes may overlap with the centers of the first to third mounting holes when viewed from the direction along the rotation axis of the rotating plate.

[0026] In the radial direction of the rotating plate, the difference between the inner dimensions of the frame and the outer dimensions of the rotating plate (dimensional difference A) is greater than the difference between the inner dimensions of the first to third mounting holes and the outer dimensions of the screw shank (hereinafter also referred to as dimensional difference C), or the difference between the inner dimensions of the three through holes and the outer dimensions of the screw shank (hereinafter also referred to as dimensional difference D).

[0027] Here, when fine-tuning the position of the optical module relative to the rotating plate, such as during assembly of the second encoder, the position of the substrate or frame to which the optical module is attached is fine-tuned. During this fine-tuning, the shanks of the screws are inserted into the corresponding mounting holes in the substrate or through-holes in the frame. Therefore, the substrate or frame (and the optical module) can only move radially around the rotating plate within a range where the shanks of the screws do not come into contact with the inner edges of the mounting holes or the inner surfaces of the through-holes. Furthermore, because of the relationship between the above-mentioned dimensional difference A and the dimensional difference C or D (dimensional difference A is greater than dimensional difference C or D), even if the substrate is moved as far as possible within this range, the inner surface of the frame does not come into contact with the outer edge of the rotating plate. Therefore, damage to the rotating plate due to contact with the frame can be prevented during assembly of the second encoder.

[0028] (Motor) A motor according to an embodiment of the present disclosure (hereinafter also referred to as a first motor) includes the first encoder described above, a shaft, a rotor, a stator, and a case. The motor may be, for example, an inner rotor type three-phase synchronous motor, but is not limited to this.

[0029] The shaft passes through the bracket of the first encoder, and the rotating plate of the first encoder is attached to the shaft and rotates with the shaft.

[0030] The rotor is attached to the shaft. The rotor may be made of, for example, but not limited to, laminated steel plates. The rotor may have a plurality of permanent magnets. The rotor may be, for example, but not limited to, an embedded magnet rotor.

[0031] The stator faces the rotor. The stator may face the rotor via an air gap. The stator may be made of, for example, but not limited to, laminated steel plates. The stator may have a plurality of teeth and coils wound around the teeth. The stator may be, for example, but not limited to, a concentrated winding stator.

[0032] The case is connected to the bracket and houses the rotor and the stator. The case and the bracket may be separate bodies or may be integrally formed. The case may be made of a non-magnetic material.

[0033] The bracket may house the rotor and stator together with the case.

[0034] A motor according to another embodiment of the present disclosure (hereinafter also referred to as a second motor) includes a bracket, a shaft, and the second encoder described above. The motor may be, for example, an inner rotor type three-phase synchronous motor, but is not limited to this.

[0035] The bracket is a member to which the second encoder is attached. The circuit board of the second encoder is fixed to the bracket together with the frame with screws.

[0036] The shaft passes through the bracket, and the rotating plate of the second encoder is attached to the shaft and rotates with the shaft.

[0037] As described above, according to the present disclosure, it is possible to prevent damage to the rotating plate when assembling the encoder, etc.

[0038] An example of an encoder and motor according to the present disclosure will be described in detail below with reference to the drawings. The components described above can be applied to the components of the example encoder and motor described below. The components of the example encoder and motor described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above embodiment. Of the components of the example encoder and motor described below, components that are not essential to the encoder and motor according to the present disclosure may be omitted. Note that the drawings shown below are schematic and do not accurately reflect the shape, dimensions, number, etc. of actual components.

[0039] First Embodiment A first embodiment of the present disclosure will be described. A motor 10 of this embodiment is an inner rotor type three-phase synchronous motor, but is not limited to this.

[0040] FIG. 1 is a cross-sectional view that schematically illustrates a motor 10 according to this embodiment. As shown in FIG. 1, the motor 10 includes a shaft 12, a rotor 15, a stator 16, a case 17, and an encoder 20 having a bracket 11. In FIGS. 1 to 10, an xyz Cartesian coordinate system is depicted to clearly illustrate the arrangement of each component. In this xyz Cartesian coordinate system, the direction from the substrate 23 toward the shaft 12 is defined as the positive direction, and the z-axis is parallel to the axis of the shaft 12. The plane parallel to the main surface of the substrate 23 is defined as the xy plane. The direction from the third mounting hole 23c of the substrate 23 toward the midpoint M shown in FIG. 2 is defined as the positive direction, and the x-axis is parallel to a line that passes from the third mounting hole 23c to the midpoint M. 2 is defined as the positive direction, and the y-axis is parallel to the line connecting the first mounting hole 23a and the second mounting hole 23b. Note that FIG. 1 is a cross-sectional view of motor 10 taken along a plane that passes through the axis of shaft 12 and is parallel to the xz plane.

[0041] The shaft 12 passes through the bracket 11 and is rotatably supported by the bracket 11 via a bearing 13. A rotating plate 21 (described later) of an encoder 20 is attached to the shaft 12, and the rotating plate 21 rotates together with the shaft 12.

[0042] The rotor 15 is attached to the shaft 12. The rotor 15 rotates together with the shaft 12. The rotor 15 in this embodiment is an embedded magnet rotor, but is not limited to this.

[0043] The stator 16 faces the rotor 15 across an air gap. The stator 16 is provided outside the rotor 15 in the radial direction of the motor 10. The stator 16 in this embodiment is a concentrated winding stator, but is not limited to this.

[0044] The case 17 is a cylindrical member with a hollow interior. The case 17 is connected to the bracket 11 and houses the rotor 15 and the stator 16. The stator 16 is fixed to the inner surface of the case 17. The case 17 is made of a non-magnetic material (for example, aluminum or an aluminum alloy). In this embodiment, the case 17 and the bracket 11 are separate bodies, but they may also be formed integrally with each other.

[0045] The encoder 20 of this embodiment is a multi-rotation absolute encoder, but is not limited to this. The encoder 20 of this embodiment is a battery-powered encoder, but may also be a battery-less encoder equipped with a permanent magnet and a power generating element. FIG. 2 is a schematic diagram of the substrate 23 of the motor 10 of embodiment 1 as viewed from the rotating plate 21. FIG. 3 is a schematic diagram of the frame 24 of the motor 10 of embodiment 1 as viewed from the case 17. As shown in FIGS. 1 to 3, the encoder 20 includes a bracket 11, a rotating plate 21, an optical module 22, a substrate 23, and a frame 24. The encoder 20 does not necessarily have to include the bracket 11; however, in this case, the bracket 11 is still a component of the motor 10.

[0046] The bracket 11 is a member for attaching the encoder 20 to the case 17. A through hole is formed in the center of the bracket 11, and the shaft 12 passes through this through hole. A bearing 13 that rotatably supports the shaft 12 is fixed to the inner surface of this through hole. The bracket 11, together with the case 17, houses the rotor 15 and the stator 16.

[0047] The rotating plate 21 is attached to the shaft 12 of the motor 10 via a boss 25. The outer shape of the rotating plate 21 is substantially circular. The boss 25 is fixed to the shaft 12 by a bolt 26 inserted into a bolt hole 25a of the boss 25.

[0048] FIG. 5 is a diagram showing the top surface of the rotating plate 21 of the motor 10 according to this embodiment, as viewed from the substrate 23. As shown in FIGS. 1 and 5, the rotating plate 21 rotates together with the shaft 12, with the shaft center of the shaft 12 serving as the rotation axis. The rotating plate 21 has a predetermined pattern 21p formed along its circumferential direction. The predetermined pattern is used to detect the rotational position and rotation speed of the shaft 12. The predetermined pattern 21p is, for example, a configuration in which a reflective area and a non-reflective area are arranged adjacent to each other in the circumferential direction. Alternatively, the predetermined pattern 21p may be formed by a reflective area formed by a pattern such as a barcode or QR code (registered trademark, the same applies hereinafter).

[0049] FIG. 6 is a cross-sectional view schematically illustrating the relative positions of the optical module 22, the substrate 23, and the rotating plate 21 of the motor 10 according to this embodiment. FIG. 7 is a plan view illustrating the arrangement of the light source 22s and the light-receiving element 22r of the optical module 22. As shown in FIG. 6, the optical module 22 includes a light source 22s (e.g., an LED (light-emitting diode)) that irradiates light onto the rotating plate 21 and a light-receiving element 22r (e.g., a photodiode). The light-receiving elements 22r are each rectangular and are arranged parallel to the long sides of the rectangle. The optical module 22 has a substantially rectangular shape as shown in FIG. 7, which will be described below, when viewed in the direction along the rotation axis of the rotating plate 21 (the vertical direction in FIG. 1; hereinafter, also referred to simply as the axial direction). However, the shape is not particularly limited. The term "substantially rectangular" includes not only a rectangular shape but also a rectangular shape with rounded corners. The light-receiving element 22r of this embodiment receives light emitted from the light source and reflected by the rotating plate 21. The light receiving element 22r may be configured to receive light that is emitted from the light source 22s and transmitted through the rotating plate 21. In the case where the light receiving element 22r is configured to receive light that is transmitted through the rotating plate 21, the light source may be disposed below the rotating plate 21 in FIG. 1. The light receiving element converts the received light into an electrical signal. This electrical signal is used to determine the rotational position and rotation speed of the shaft 12.

[0050] 6 shows a configuration in which the optical module 22 has both the light source 22s and the light receiving element 22r, the optical module 22 may have either the light source 22s or the light receiving element 22r. For example, the optical module 22 may have the light receiving element 22r, and the light source 22s may be provided directly on the substrate 23.

[0051] An optical module 22 is attached to the substrate 23. In addition, various electronic components 27 are mounted on the substrate 23.

[0052] FIG. 2 is a schematic diagram of the substrate 23 as viewed from the rotating plate 21 in the motor 10 according to this embodiment. As shown in FIG. 2, the substrate 23 is substantially disk-shaped and has a first mounting hole 23a, a second mounting hole 23b, and a third mounting hole 23c. As shown in FIG. 1 by the portion of the third mounting hole 23c, screws 14 (or bolts) are inserted into the first mounting hole 23a to the third mounting hole 23c, respectively, for attaching the substrate 23 together with the frame 24 to the bracket 11. The screws 14 fix the substrate 23 and the frame 24 in a mutually positioned state. In other words, the relative positional relationship between the screws 14 and the bracket 11 is fixed. The first mounting hole 23a to the third mounting hole 23c are substantially circular and penetrate the substrate 23 in its thickness direction. The term "substantially circular" refers to a shape in which, for example, 80% or more of the outer edge is formed by a circular arc.

[0053] The optical module 22 is disposed at a position overlapping the midpoint M of a first line segment L1 connecting the center of the first mounting hole 23a and the center of the second mounting hole 23b, as viewed in the axial direction. The optical module 22 is divided into a first region 22a and a second region 22b by the first line segment L1. The ratio of the area of ​​the first region 22a to the area of ​​the second region 22b is 1:1. In this embodiment, the center point (the intersection of two diagonals) of the rectangular optical module 22 coincides with the midpoint M of the first line segment L1, as viewed in the axial direction. However, it is sufficient that the optical module 22 is disposed so that at least a portion thereof overlaps the first line segment L1, as viewed in the axial direction. This arrangement prevents the optical module 22 from tilting and enables it to be stably held. The distance between the center point of the optical module 22 and the midpoint M of the first line segment L1 may be, for example, 5 mm or less.

[0054] The first line segment L1, the second line segment L2 connecting the center of first mounting hole 23a and the center of third mounting hole 23c, and the third line segment L3 connecting the center of second mounting hole 23b and the center of third mounting hole 23c form an isosceles triangle with a base angle larger than the apex angle and with first line segment L1 as the base. In this way, first mounting hole 23a to third mounting hole 23c are arranged at positions that are rotationally asymmetric around the rotation axis of rotating plate 21.

[0055] The frame 24 is fixed to the bracket 11. The frame 24 is substantially cylindrical. The frame 24 houses the rotating plate 21 and supports the substrate 23 so that the optical module 22 faces the rotating plate 21 (more specifically, the area of ​​the rotating plate 21 on which a predetermined pattern is formed). The substrate 23 is fixed to the frame 24 by a predetermined fixing means. Specifically, the substrate 23 is fixed to the frame 24 by screws 14.

[0056] In addition, when fixing the substrate 23 to the frame 24, for example, the two may be fixed to each other by press-fitting pins of the frame 24 into pin holes formed in the substrate 23.

[0057] Fig. 3 is a schematic diagram showing the frame 24 of the motor 10 according to this embodiment as viewed from the case 17. Fig. 8 is a schematic diagram showing the bracket 11 of the motor 10 according to this embodiment as viewed from the board 23. Fig. 9 is a diagram showing the positional relationship between the bracket 11, the inner peripheral surface of the frame 24, and the outer peripheral surface of the boss 25 when the bracket 11 is viewed from the board 23 in the motor 10 according to this embodiment. In Fig. 9, the positions corresponding to the protrusions 24a of the frame 24 and the inner peripheral surface of the frame 24 are indicated by dashed lines, and the positions corresponding to the outer peripheral surface of the boss 25 are indicated by dashed lines.

[0058] As shown in FIG. 3, the frame 24 has three through holes 24b, through which the screws 14 are respectively inserted. The three through holes 24b are provided at positions corresponding to the first to third mounting holes 23a to 23c of the substrate 23. The inner dimension (inner diameter) D7 (see FIG. 1) of each through hole 24b is substantially equal to, but may be different from, the inner dimension (inner diameter) D6 (see FIG. 1) of the first to third mounting holes 23a to 23c of the substrate 23. Each through hole 24b penetrates the frame 24 in its thickness direction (the vertical direction in FIG. 1, i.e., the z-axis direction). The frame 24 and substrate 23 are fixed to the bracket 11 with the screws 14.

[0059] As shown in FIG. 8, the bracket 11 has three recesses 11a on its surface facing the frame 24 (the upper surface in FIG. 1). The three recesses 11a are recessed in the z-axis direction. The three recesses 11a are arranged at equal intervals (at 120° intervals) around the circumference of the motor 10. Each recess 11a is substantially circular. However, the shape of each recess 11a may be any shape, such as oval, rectangular, or polygonal.

[0060] As shown in FIGS. 3 and 8, the frame 24 has three protrusions 24a at positions corresponding to the three recesses 11a, respectively, which fit into the three recesses 11a of the bracket 11 via gaps (gaps in the radial direction of the rotating plate 21). The three protrusions 24a protrude in the z-axis direction. The three protrusions 24a are arranged at equal intervals (at 120° intervals) in the circumferential direction of the frame 24. Each protrusion 24a is substantially circular. However, the shape of each protrusion 24a may be any shape, such as an oval, rectangle, or polygon.

[0061] As shown in FIGS. 1 and 9 , in the radial direction of the rotating plate 21 (for example, the left-right direction (x-axis direction) in FIG. 1 ; hereinafter, simply referred to as the radial direction), the difference (dimension difference A) between the inner dimension (inner diameter) D1 of the frame 24 and the outer dimension (outer diameter) D2 of the rotating plate 21 is greater than the difference (dimension difference B) between the inner dimension (inner diameter) D3 of the recess 11a of the bracket 11 and the outer dimension (outer diameter) D4 of the protrusion 24a of the frame 24. The dimension difference B corresponds to the maximum movable distance of the protrusion 24a relative to the recess 11a. For example, the dimension difference A may be 2 mm or more and 3 mm or less, and the dimension difference B may be 0.5 mm or more and 1.5 mm or less. The inner dimension D1 of the frame 24 is greater than the outer dimension D2 of the rotating plate 21 (D1>D2), and the inner dimension D3 of the recess 11a is greater than the outer dimension D4 of the protrusion 24a (D3>D4). By doing so, the convex portion 24a of the frame 24 and the inner peripheral surface of the frame 24 are always positioned outside the outer peripheral surface of the boss 25 in the radial direction.

[0062] 1, in the radial direction, the dimensional difference A is larger than the difference (dimensional difference C) between the inner dimension (inner diameter) D6 of the first mounting hole 23a of the substrate 23 and the outer dimension (outer diameter) D5 of the shank of the screw 14. The dimensional difference C corresponds to the maximum movable distance of the substrate 23 relative to the screw 14. As an example, the dimensional difference C may be 0.5 mm or more and 1.5 mm or less. The inner dimension D6 of the first mounting hole 23a is larger than the outer dimension D5 of the shank of the screw 14 (D6>D5).

[0063] Furthermore, in the radial direction, the dimensional difference A is larger than the difference (dimensional difference D) between the inner dimension (inner diameter) D7 of the through hole 24b of the frame 24 and the outer dimension D5 of the shank of the screw 14. The dimensional difference D corresponds to the maximum movable distance of the frame 24 relative to the screw 14. As an example, the dimensional difference D may be 0.5 mm or more and 1.5 mm or less. Note that the inner dimension D7 of the through hole 24b is larger than the outer dimension D5 of the shank of the screw 14 (D7>D5).

[0064] The magnitude relationship between the dimensional difference A and the dimensional differences B to D provides the following advantage. Specifically, when fine-tuning the relative position of the optical module 22 with respect to the rotating plate 21, such as during assembly of the encoder 20, the positions of the substrate 23 and the frame 24 to which the optical module 22 is attached are fine-tuned. During this fine adjustment, the radial movement range of the frame 24 and the substrate 23 relative to the rotating plate 21 is limited due to physical interference between components with relatively small dimensional differences B to D (for example, between the frame 24 having the convex portion 24a and the bracket 11 having the concave portion 11a). Within this limited movement range, no physical interference occurs between the frame 24 and the rotating plate 21, where the relatively large dimensional difference A exists. Therefore, the convex portion 24a of the frame 24 and the inner peripheral surface of the frame 24 are always positioned outside the outer peripheral surface of the boss 25. This prevents damage to the rotating plate 21 due to contact between the frame 24 and the boss 25 during assembly of the encoder 20.

[0065] The positions of the light source 22s and the light receiving element 22r disposed in the optical module 22 will be described below with reference to Fig. 7. Fig. 7 is a plan view of the optical module 22 as viewed from the rotating plate 21 in the motor 10 according to this embodiment.

[0066] The optical module 22 is divided into a first region 22a and a second region 22b by a first line segment L1. A plurality of light receiving elements 22r are arranged in the first region 22a, and a light source 22s is arranged in the second region 22b. Each of the plurality of light receiving elements 22r has a rectangular shape and is arranged parallel to the long side of the rectangle. In this manner, the optical module 22 is arranged so that at least a portion thereof overlaps with the first line segment L1 when viewed from the axial direction, which prevents the optical module 22 from tilting when screwed in place and allows the optical module 22 to be stably held.

[0067] In FIG. 7, the multiple light-receiving elements 22r are arranged so that their long sides are perpendicular to the first line segment L1. However, this arrangement is not limited to this. For example, the multiple light-receiving elements 22r may be arranged so that their long sides are parallel to the first line segment L1. In the example of FIG. 7, the optical module 22 includes three light-receiving elements 22r. However, the number of light-receiving elements is not limited to three. The optical module 22 includes multiple light-receiving elements 22r so that the rotational position and rotation speed of the shaft 12 can be accurately determined by irradiating light from the light source 22s across the multiple light-receiving elements 22r. While the multiple light-receiving elements 22r have the same shape, they may each have a different shape, or two may have the same shape and the remaining two may have different shapes. Furthermore, if only the light intensity of the light source 22s is to be obtained, a single light-receiving element 22r may be used.

[0068] 7, the light source 22s may be arranged in the first region 22a, and a plurality of light receiving elements 22r may be arranged in the second region 22b. The light source 22s and one of the plurality of light receiving elements 22r may be arranged so as to overlap with the first line segment L1.

[0069] <Variations> FIG. 10 is a cross-sectional view schematically illustrating the relative positions of the optical module 22, the substrate 23, and the rotating plate 21 in a modified example of the motor 10 according to the present embodiment. In this modified example, the light receiving element 22r is fixed to the optical module 22, and the light source 22s is fixed to the bracket 11. Light Lb emitted from the light source 22s passes through a pattern 21p provided on the rotating plate 21 and is incident on the light receiving element 22r. The light receiving element 22r can read the pattern obtained by the light Lb passing through the pattern 21p, thereby reading the rotation speed and rotation angle of the rotating plate 21. In this case, the predetermined pattern 21p is configured, for example, with a transmissive region and a non-transmissive region arranged adjacent to each other in the circumferential direction. The transmissive region can be formed, for example, by a through-hole provided in the rotating plate 21. The transmissive region of the predetermined pattern 21p may be formed by a pattern such as a barcode or a QR code.

[0070] In the above modified example, instead of the light receiving element 22r being fixed to the optical module 22 and the light source 22s being fixed to the bracket 11, the light source 22s may be fixed to the optical module 22 and the light receiving element 22r may be fixed to the bracket 11.

[0071] Second Embodiment A second embodiment of the present disclosure will be described. This embodiment differs from the first embodiment in the arrangement of the optical module 22 and the like on the substrate 23. The other configurations are the same as those of the first embodiment. Below, differences from the first embodiment will be mainly described.

[0072] 4 is a schematic diagram of the substrate 23 as viewed from the rotating plate 21 in the motor 10 according to this embodiment. As shown in FIG. 4, the optical module 22 is disposed on the first line segment L1 when viewed from the axial direction, but is disposed at a position that does not overlap with the midpoint M of the first line segment L1. In addition, in the optical module 22, the ratio of the area of ​​the first region 22a to the area of ​​the second region 22b is 1:2. Thus, even if the optical module 22 is not disposed at a position that overlaps with the midpoint M of the first line segment L1 when viewed from the axial direction, or even if the center point of the optical module 22 is not located on the first line segment L1, the effects of the present disclosure can be obtained.

[0073] Moreover, the first to third mounting holes 23a to 23c are arranged at positions that are rotationally symmetric about the rotation axis of the rotating plate 21. More specifically, the first to third mounting holes 23a to 23c are arranged concentrically about the axis of the shaft 12, and are arranged at equal intervals (at 120° intervals) in the circumferential direction of the substrate 23. Therefore, in this embodiment, the first line segment L1, the second line segment L2, and the third line segment L3 form an equilateral triangle. [Industrial Applicability]

[0074] The present disclosure can be used for an encoder and a motor equipped with the encoder. [Explanation of symbols]

[0075] 10: Motor 11: Bracket 11a: Recess 12: Shaft 13: Bearing 14: Screw 15: Rotor 16: Stator 17: Case 20: Encoder 21: Rotating plate 22: Optical module 22a: 1st area 22b:Second area 23: Circuit board 23a: First mounting hole 23b: Second mounting hole 23c: Third mounting hole 24: Frame 24a: Convex part 24b: Through hole 25: Boss 25a: Bolt hole 26: Bolt D1: Inner dimension D2: External dimensions D3: Inner dimension D4: External dimensions D5: External dimensions D6:Inner dimension D7:Inner dimension L1: First line segment L2: Second line segment L3: Third line segment M: Midpoint

Claims

1. A bracket and A rotating plate that rotates around a rotation axis; an optical module facing the rotary plate and including at least one of a light source that irradiates light onto the rotary plate and a light receiving element that receives the light reflected by the rotary plate or the light that has passed through the rotary plate; a substrate on which the optical module is disposed; a frame fixed to the bracket and supporting the substrate; Equipped with the bracket has three or more recesses on a surface facing the frame, the frame has three or more protrusions at positions corresponding to the three or more recesses, each of which fits into the recesses of the bracket via a gap; an encoder in which a difference between an inner dimension of the frame and an outer dimension of the rotary plate in a radial direction of the rotary plate is larger than a difference between an inner dimension of the recess and an outer dimension of the protrusion.

2. The encoder according to claim 1 , wherein three or more of the protrusions are arranged at positions rotationally asymmetric around the rotation axis.

3. An encoder according to claim 1 or 2; a shaft passing through the bracket; a rotor attached to the shaft; a stator facing the rotor; a case coupled to the bracket and housing the rotor and the stator; Equipped with The rotating plate is attached to the shaft and rotates with the shaft.

4. The motor of claim 3 , wherein the bracket houses the rotor and the stator together with the case.

5. The substrate has a first mounting hole, a second mounting hole, and a third mounting hole through which screws are inserted to fix the substrate and the frame in a mutually positioned state, the frame has three through holes provided at positions corresponding to the first to third mounting holes, respectively, and through which the screws are inserted; In the radial direction of the rotary plate, the difference between the inner dimension of the frame and the outer dimension of the rotary plate is larger than the difference between the inner dimensions of the first to third mounting holes and the outer dimension of the shank of the screw, or the difference between the inner dimensions of the three through holes and the outer dimension of the shank of the screw. The encoder of claim 1 .

6. A shaft passing through the bracket; an encoder according to claim 5; Equipped with the rotating plate is attached to the shaft and rotates with the shaft; The substrate, together with the frame, is fixed to the bracket with the screws.

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