Encoder and motor equipped with it

Abstract

The present invention stably retains an optical module. The disclosed encoder comprises: a rotating plate that rotates around a rotational axis; an optical module (22) that includes a light source for shining a light at the rotating plate, and / or a light receiving element for receiving light which has been reflected by the rotating plate or light which has passed through the rotating plate; a substrate (23) on which the optical module (22) is positioned; and a frame that supports the substrate. The substrate (23) has a first attachment hole (23a) and a second attachment hole (23b), and is screwed to the frame using a first screw that is inserted into the first attachment hole (23a) and a second screw that is inserted into the second attachment hole (23b). As viewed from the direction along the rotational axis, the optical module (22) is positioned on a first line segment (L1) that connects the center of the first attachment hole (23a) and the center of the second attachment hole (23b).

Description

Technical Field

[0001] The present disclosure relates to an encoder and a motor provided with the same.

Background Art

[0002] Conventionally, an encoder for detecting the rotational position of a motor shaft has been known (for example, 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 for detecting the predetermined pattern. This main body is fixed to a predetermined object at a fixed position arranged symmetrically with respect to a virtual straight line connecting the detector and the center of the shaft when viewed from the axial direction of the shaft.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] However, in the encoder of Patent Document 1, since the stress due to fixation acts on the detector non-uniformly, there is a possibility that the detector is held in an unstable state (for example, a tilted state). When the detector (or the optical module) is held in such an unstable state, the detection accuracy of the encoder may decrease. In such a situation, one of the objectives of the present disclosure is to stably hold the optical module.

[0005] One aspect of the present disclosure relates to an encoder. The encoder comprises a rotating plate that rotates about a rotation axis; an optical module including at least one of a light source that irradiates light onto the rotating plate and a light-receiving element that receives the light reflected by the rotating plate or the light transmitted through the rotating plate; a substrate on which the optical module is arranged; and a frame that supports the substrate. The substrate has a first mounting hole and a second mounting hole, and is screwed to the frame by a first screw inserted into the first hole and a second screw inserted into the second hole, and when viewed from a direction along the rotation axis, the optical module is arranged on a first line segment connecting the center of the first mounting hole and the center of the second mounting hole.

[0006] Another aspect of this disclosure relates to a motor. The motor comprises a bracket, a shaft passing through the bracket, and the encoder described above, wherein the shaft is attached to the rotating plate and rotates together with the rotating plate, and the substrate is fixed to the bracket together with the frame by screws.

[0007] According to this disclosure, the optical module can be held stably. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view showing the motor according to Embodiment 1. [Figure 2] This is a schematic diagram of the circuit board as viewed from the rotating plate in the motor according to Embodiment 1. [Figure 3] This is a schematic diagram showing the frame of the motor according to Embodiment 1 as viewed from the case. [Figure 4] This is a schematic diagram of the circuit board as viewed from the rotating plate in the motor according to Embodiment 2. [Figure 5] This figure shows the upper surface of the rotating plate of the motor according to Embodiment 1, as seen from the circuit board. [Figure 6] This is a schematic cross-sectional view showing the relationship between the arrangement of the optical module, substrate, and rotating plate in the motor according to Embodiment 1. [Figure 7] This is a plan view showing the arrangement of the light source and light receiving element of the optical module of the motor according to Embodiment 1. [Figure 8] This is a plan view showing the arrangement of the light source and light-receiving element in another arrangement example 1 of the optical module of the motor according to Embodiment 1. [Figure 9] This is a plan view showing the arrangement of the light source and light-receiving elements in another arrangement example 2 of the optical module of the motor according to Embodiment 1. [Figure 10] This is a plan view showing the arrangement of the light source and light-receiving element in another arrangement example 3 of the optical module of the motor according to Embodiment 1. [Figure 11] This is a schematic cross-sectional view showing the relationship between the arrangement of the optical module, substrate, and rotating plate in a modified example 1 of the motor according to Embodiment 1. [Figure 12] This is a schematic cross-sectional view showing the relationship between the arrangement of the optical module, substrate, and rotating plate in a modified example 2 of the motor according to Embodiment 1. [Modes for carrying out the invention]

[0009] Embodiments of encoders and motors relating to this disclosure are described below with examples. However, this disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values ​​and materials may be applied as long as the effects of this disclosure are achieved.

[0010] (Encoder) The encoder according to this disclosure comprises a rotating plate, an optical module, a substrate, and a frame.

[0011] The rotating plate rotates around a rotation axis. The rotating plate may be attached to the motor shaft. The rotating plate may be attached to the shaft directly or indirectly. In the latter case, for example, the rotating plate is fixed to a boss fixed to the shaft. The rotating plate rotates with the shaft, with the shaft's axis as the axis of rotation. The rotating plate has a predetermined pattern formed along its circumferential direction. The predetermined pattern may be used to detect the rotational position of the shaft, or it may be used to detect both the rotational position and the number of rotations 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 number of rotations of the shaft refers to the number of times the shaft has rotated.

[0012] The optical module includes at least one of a light source that illuminates a rotating plate and a light-receiving element. The light-receiving element receives light that has been illuminated from the light source and reflected by the rotating plate (reflected light) or light that has passed through the rotating plate (transmitted light). When the light-receiving element receives reflected light, both the light source and the light-receiving element are positioned 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 positioned on one side of the rotating plate, and the other on the other side. The light-receiving element may convert the received light into an electrical signal. This electrical signal may be used to determine the rotational position and rotational speed of the shaft.

[0013] An optical module is mounted on the substrate. Various electronic components may be mounted on the substrate. The substrate may be substantially disc-shaped. "Substantially disc-shaped" means, for example, a plate shape in which more than 80% of the outer edge is composed of a circular arc.

[0014] The frame accommodates the rotating plate and supports the substrate such 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 inside having a diameter larger than the diameter 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.

[0015] Here, the above-mentioned substrate has a first mounting hole and a second mounting hole through which a screw for fixing the substrate and the frame in a positioned state is inserted. And, when viewed from the direction along the rotation axis of the rotating plate, the above-mentioned optical module is arranged on a first line segment connecting the center of the first mounting hole and the center of the second mounting hole. That the optical module is arranged on the first line segment means that at least a part of the optical module overlaps with the first line segment when viewed from the direction along the rotation axis of the rotating plate. According to such an arrangement, stress acts substantially uniformly on the optical module by the screws inserted into the first and second mounting holes. Therefore, it is possible to avoid the optical module from tilting and hold it stably.

[0016] When viewed from the direction along the rotation axis of the rotating plate, the optical module may be substantially rectangular and divided into a first region and a second region by the first line segment, and the ratio of the area of the first region to the area of the second region may be 1:1 to 1:2. Further, the ratio of the area of the first region to the area of the second region may be 1:1. By setting the ratio of the area of the first region to the area of the second region in this way, it is possible to further suppress the optical module from tilting. Note that the substantially rectangular shape includes not only the rectangular shape but also a shape in which the corners of the rectangle are rounded.

[0017] When viewed in the direction along the rotation axis of the rotating plate, the optical module may be disposed at a position overlapping the midpoint of the first line segment. Here, the optical module being disposed at a position overlapping the midpoint of the first line segment means that at least a part of the optical module overlaps the midpoint when viewed in the direction along the rotation axis of the rotating plate. According to such an arrangement, it is possible to further suppress the tilting of the optical module.

[0018] The substrate may further have a third mounting hole. The first mounting hole, the second mounting hole, and the third mounting hole may be disposed at positions that are rotationally asymmetric around the rotation axis of the rotating plate. According to this configuration, in the circumferential direction of the rotating plate, the relative positions between the substrate or the frame and the mounting target (for example, a bracket) are specified by the first to third mounting holes and the corresponding screw holes of the mounting target. Therefore, it is possible to prevent assembly errors of the encoder. Note that the first to third mounting holes may be disposed at positions that are rotationally symmetric around the rotation axis of the rotating plate.

[0019] When the substrate is viewed along the rotation axis of the rotating plate, the first line segment, the second line segment connecting the centers of the first mounting hole and the third mounting hole, and the third line segment connecting the centers of the second mounting hole and the third mounting hole may form an isosceles triangle having a base angle larger than the apex angle and having the first line segment as the base. According to this configuration, by further equalizing the stress acting on the optical module, it is possible to further suppress the tilting of the optical module. Furthermore, it becomes possible to dispose the optical module at a position far from the rotation axis of the rotating plate, and a predetermined pattern facing the optical module can be formed at a position close to the outer edge of the rotating plate. Since it is easier to form the predetermined pattern on the outer edge side than on the center side of the rotating plate, it becomes possible to easily manufacture the encoder.

[0020] The frame may have three through holes, each positioned to correspond to the first to third mounting holes, through which screws are inserted. 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) may be greater than the difference between the inner dimensions of the three through holes (inner diameter if each through hole is circular) and the outer dimensions of the screw shafts (hereinafter also referred to as dimensional difference D). When fine-tuning the relative position of the optical module with respect to the rotating plate during encoder assembly, the position of the substrate and frame to which the optical module is attached will be fine-tuned. During this fine-tuning, since the screw shafts are inserted into the through holes of the frame, the frame (and the substrate and optical module) can only move within a range in which the screw shafts do not contact the inner surface of the through holes in the radial direction of the rotating plate. Furthermore, due to the relative magnitudes of dimensional difference A and dimensional difference D described above, even if the frame is moved to its maximum extent within this range, the inner surface of the frame will not contact the outer edge of the rotating plate. Therefore, damage to the rotating plate due to contact with the frame during encoder assembly can be prevented.

[0021] In the radial direction of the rotating plate, the difference between the inner dimension (or inner diameter) of the frame and the outer dimension (or outer diameter) of the rotating plate (hereinafter also referred to as dimensional difference A) may be greater than the difference between the inner dimension (or inner diameter) of the first and second mounting holes (if each mounting hole is circular, the inner diameter) and the outer dimension (or outer diameter) of the screw shaft (hereinafter also referred to as dimensional difference C). Here, when fine-tuning the relative position of the optical module with respect to the rotating plate during encoder assembly, the position of the substrate and frame to which the optical module is attached will be fine-tuned. During this fine-tuning, since the screw shaft is inserted through the mounting hole in the substrate, the substrate (and frame and optical module) can only move within a range in the radial direction of the rotating plate where the screw shaft does not contact the inner edge of the mounting hole. And, because of the relative magnitudes of dimensional difference A and dimensional difference C described above, even if the substrate is moved to its maximum extent within that range, the inner surface of the frame will not contact the outer edge of the rotating plate. Therefore, damage to the rotating plate due to contact with the frame during encoder assembly can be prevented.

[0022] (motor) The motor according to this disclosure comprises a bracket, a shaft, and the encoder described above. The motor may also comprise a rotor mounted on the shaft and a stator facing the rotor across a gap. The motor may be, for example, an inner-rotor type three-phase synchronous motor, but is not limited thereto.

[0023] The bracket is the component to which the encoder is mounted. The encoder's circuit board is secured to the bracket with screws along with the frame.

[0024] The shaft passes through the bracket. The shaft is attached to the encoder's rotating plate and rotates together with the plate.

[0025] As described above, according to this disclosure, the optical module can be held stably, and a decrease in the detection accuracy of the encoder can be avoided.

[0026] Hereinafter, an example of an encoder and motor according to this disclosure will be specifically described with reference to the drawings. The components of the encoder and motor example described below can be the components described above. The components of the encoder and motor example described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above embodiments. Among the components of the encoder and motor example described below, components that are not essential to the encoder and motor according to this disclosure may be omitted. Note that the figures shown below are schematic and do not accurately reflect the shape, dimensions, number, etc. of the actual components.

[0027] Embodiment 1 Embodiment 1 of this disclosure will now be described. The motor 10 in this embodiment is an inner rotor type three-phase synchronous motor, but is not limited thereto.

[0028] Figure 1 is a schematic cross-sectional view showing the motor 10 according to this embodiment. As shown in Figure 1, the motor 10 comprises a shaft 12, a rotor 15, a stator 16, a case 17, and an encoder 20 having a bracket 11.

[0029] 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 the encoder 20 is attached to the shaft 12, and this rotating plate 21 rotates together with the shaft 12.

[0030] 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 type rotor, but is not limited to this.

[0031] The stator 16 faces the rotor 15 via an air gap. The stator 16 is located on the outside of the rotor 15 in the radial direction of the motor 10. The stator 16 in this embodiment is a concentrated winding type stator, but is not limited to this.

[0032] The case 17 is a hollow cylindrical member. The case 17 is coupled 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 components, but they may be integrally formed with each other.

[0033] The encoder 20 in this embodiment is a multi-turn absolute encoder, but is not limited to this. The encoder 20 in this embodiment is a battery-powered encoder, but may also be a battery-less encoder equipped with a permanent magnet and a power generation element. As shown in Figure 1, the encoder 20 comprises a bracket 11, a rotating plate 21, an optical module 22, a circuit board 23, and a frame 24. The encoder 20 does not necessarily have to include the bracket 11, but even in this case, the bracket 11 is a component of the motor 10.

[0034] Bracket 11 is a component for attaching the encoder 20 to the case 17. A through hole is formed in the center of the bracket 11, through which the shaft 12 passes. 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.

[0035] 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 bolts 26 inserted through its bolt holes 25a. The rotating plate 21 rotates with the shaft 12, with the shaft 12's axis as the axis of rotation.

[0036] Figure 5 shows the upper surface of the rotating plate 21 of the motor 10 according to this embodiment, as seen from the substrate 23. As shown in Figure 5, the rotating plate 21 has a predetermined pattern 21p formed along its circumferential direction. The predetermined pattern 21p is used to detect the rotational position and rotational speed of the shaft 12. The predetermined pattern 21p may be, for example, a barcode or a QR code (registered trademark).

[0037] Figure 6 is a schematic cross-sectional view showing the relationship between the arrangement of the optical module 22, the substrate 23, and the rotating plate 21 of the motor 10 according to this embodiment. Figure 7 is a plan view showing the arrangement of the light source 22s and the light-receiving element 22r of the optical module 22. As shown in Figure 6, the optical module 22 has a light source 22s (e.g., an LED (light-emitting diode)) that irradiates the rotating plate 21 with light, and a light-receiving element 22r (e.g., a photodiode). There are multiple light-receiving elements 22r, each having a rectangular shape, and they are arranged parallel to the longer side of the rectangle. When viewed from the direction along the rotation axis of the rotating plate 21 (the up and down direction in Figure 1; hereinafter simply referred to as the axial direction), the optical module 22 is substantially rectangular, as shown in Figure 7 which will be described below, but the shape is not particularly limited. A substantially rectangular shape includes not only a rectangular shape but also shapes such as a rectangle with rounded corners. In this embodiment, the light-receiving element 22r receives light Lb that is irradiated from the light source 22s and reflected by the rotating plate 21. The light-receiving element 22r may also be configured to receive light that is irradiated from the light source 22s and transmitted through the rotating plate 21. In the case where the light-receiving element 22r receives light that has been transmitted through the rotating plate 21, the light source may be placed below the rotating plate 21 in Figure 1. The light-receiving element converts the received light into an electrical signal. This electrical signal is used to determine the rotational position and rotational speed of the shaft 12. Although the example in Figure 6 shows a configuration in which the optical module 22 has both a light source 22s and a light-receiving element 22r, the optical module 22 may have either a light source 22s or a light-receiving element 22r. For example, the optical module 22 may have a light-receiving element 22r and the light source 22s may be directly provided on the substrate 23.

[0038] An optical module 22 is mounted on the circuit board 23. Various electronic components 27 are also mounted on the circuit board 23.

[0039] Figure 2 is a schematic diagram of the substrate 23 as seen from the rotating plate 21 in the motor 10 according to this embodiment. As shown in Figure 2, the substrate 23 is substantially disc-shaped and has a first mounting hole 23a, a second mounting hole 23b, and a third mounting hole 23c. Screws 14 (or bolts) for attaching the substrate 23 to the bracket 11 together with the frame 24 are inserted through the first mounting hole 23a to the third mounting hole 23c, as shown in the portion of the third mounting hole 23c in Figure 1. The screws 14 fix the substrate 23 and the frame 24 in a relative position. That is, 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 the thickness direction. "Substantially circular" means, for example, a shape in which more than 80% of the outer edge is composed of a circular arc.

[0040] The optical module 22 is positioned so as to coincide with the midpoint M of the first line segment L1, which connects the center of the first mounting hole 23a and the center of the second mounting hole 23b, when viewed from 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, when viewed from the axial direction, the center point of the rectangular optical module 22 (the intersection of the two diagonals) and the midpoint M of the first line segment L1 coincide with each other. However, the optical module 22 only needs to be positioned so that at least a part of it coincides with the first line segment L1 when viewed from the axial direction. This arrangement prevents the optical module 22 from tilting and makes it possible to hold it stably. 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.

[0041] The first line segment L1 described above, the second line segment L2 connecting the center of the first mounting hole 23a and the center of the third mounting hole 23c, and the third line segment L3 connecting the center of the second mounting hole 23b and the center of the third mounting hole 23c form an isosceles triangle with a base angle greater than the vertex angle and the first line segment L1 as the base. In this way, the first mounting holes 23a to the third mounting holes 23c are positioned in a rotationally asymmetrical manner around the rotation axis of the rotating plate 21.

[0042] 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 such that the optical module 22 faces the rotating plate 21 (more specifically, the region on the rotating plate 21 where a predetermined pattern is formed). The substrate 23 is fixed to the frame 24 by predetermined fastening means. Specifically, the substrate 23 is fixed to the frame 24 by screws 14.

[0043] Furthermore, when fixing the substrate 23 to the frame 24, for example, the two may be fixed to each other by press-fitting the pins of the frame 24 into pin holes formed in the substrate 23.

[0044] Figure 3 is a schematic diagram showing the frame 24 of the motor 10 according to this embodiment as viewed from the case 17. As shown in Figure 3, the frame 24 has three through holes 24b through which the screws 14 described above are inserted. The three through holes 24b are provided at positions corresponding to the first mounting holes 23a to the third mounting holes 23c of the substrate 23. The inner dimension D7 of each through hole 24b is substantially equal to, but may differ from, the inner dimension D6 of the first mounting holes 23a to the third mounting holes 23c of the substrate 23. Each through hole 24b penetrates the frame 24 in its thickness direction (vertical direction in Figure 1). The frame 24 and the substrate 23 are fixed to the bracket 11 by screws 14.

[0045] Here, the bracket 11 has three recesses 11a on the surface facing the frame 24 (the top surface in Figure 1). The three recesses 11a are recessed in the axial direction. The three recesses 11a are arranged at equal intervals (120° intervals) in the circumferential direction of the motor 10. Each recess 11a is substantially circular. However, the shape of each recess 11a may be any shape, such as an ellipse, rectangle, or polygon.

[0046] The frame 24 has three protrusions 24a that fit into the recesses 11a of the bracket 11 through a gap (a gap in the radial direction of the rotating plate 21) at positions corresponding to the three recesses 11a. The three protrusions 24a protrude in the axial direction. The three protrusions 24a are arranged at equal intervals (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 ellipse, rectangle, or polygon.

[0047] As shown in Figure 1, in the radial direction of the rotating plate 21 (left-right direction in Figure 1; hereinafter also simply referred to as the radial direction), the difference between the inner dimension D1 of the frame 24 and the outer dimension D2 of the rotating plate 21 (dimensional difference A) is greater than the difference between the inner dimension D3 of the recess 11a of the bracket 11 and the outer dimension D4 of the protrusion 24a of the frame 24 (hereinafter also referred to as the dimensional difference B). The dimensional difference B corresponds to the maximum movable distance of the protrusion 24a relative to the recess 11a. For example, the dimensional difference A may be 2 mm or more and 3 mm or less, and the dimensional difference B may be 0.5 mm or more and 1.5 mm or less. Note that 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).

[0048] Furthermore, in the radial direction, the dimensional difference A is greater than the difference (dimensional difference C) between the inner dimension D6 of the first mounting hole 23a of the substrate 23 and the outer dimension D5 of the shaft portion of the screw 14. The dimensional difference C corresponds to the maximum movable distance of the substrate 23 relative to the screw 14. For example, the dimensional difference C may be 0.5 mm or more and 1.5 m or less. Note that the inner dimension D6 of the first mounting hole 23a is greater than the outer dimension D5 of the shaft portion of the screw 14 (D6 > D5).

[0049] Furthermore, in the radial direction, the dimensional difference A is greater than the difference (dimensional difference D) between the inner dimension D7 of the through hole 24b of the frame 24 and the outer dimension D5 of the shaft portion of the screw 14. The dimensional difference D corresponds to the maximum movable distance of the frame 24 relative to the screw 14. For 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 greater than the outer dimension D5 of the shaft portion of the screw 14 (D7 > D5).

[0050] The relative magnitudes of the dimensional difference A and dimensional differences B to D described above provide the following advantages. Specifically, when fine-tuning the relative position of the optical module 22 with respect to the rotating plate 21 during the assembly of the encoder 20, the positions of the substrate 23 and frame 24 to which the optical module 22 is attached are fine-tuned. During this fine-tuning, physical interference between components with relatively small dimensional differences B to D (for example, between the frame 24 having a protrusion 24a and the bracket 11 having a recess 11a) limits the radial range of movement of the frame 24 and substrate 23 relative to the rotating plate 21. Within this limited range of movement, no physical interference occurs between the frame 24 and the rotating plate 21 where a relatively large dimensional difference A exists. Therefore, damage to the rotating plate 21 due to contact with the frame 24 during the assembly of the encoder 20 can be prevented.

[0051] The positions of the light source 22s and the light receiving element 22r, which are located in the optical module 22, will be explained below with reference to Figure 7. Figure 7 is a plan view of the optical module 22 as seen from the rotating plate 21 in the motor 10 according to this embodiment.

[0052] The optical module 22 is divided into a first region 22a and a second region 22b by a first line segment L1. Multiple 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 multiple light-receiving elements 22r has a rectangular shape and is arranged parallel to the longer side of the rectangle. In this way, when viewed from the axial direction, at least a part of the optical module 22 overlaps with the first line segment L1, which prevents the optical module 22 from tilting and makes it possible to hold it stably.

[0053] In Figure 7, the multiple photodetectors 22r are arranged so that their respective long sides are parallel to the first line segment L1. However, the arrangement is not limited to this; for example, the multiple photodetectors 22r may be arranged so that their long sides are perpendicular to the first line segment. Also, in the example in Figure 7, the optical module 22 has three photodetectors 22r, but it is not limited to three; it may have two or four or more photodetectors. The optical module 22 has multiple photodetectors 22r in order to accurately determine the rotational position and rotational speed of the shaft 12 by illuminating the multiple photodetectors 22r with light from the light source 22s. Although the multiple photodetectors 22r have the same shape, they may each have different shapes, or two may have the same shape and the remaining one may have a different shape. Furthermore, if only the light intensity of the light source 22s is to be obtained, a single photodetector 22r may be used.

[0054] <Another example of optical module configuration 1> Another arrangement example 1 of the optical module 22 is shown in Figure 8. Figure 8 is a plan view showing the arrangement of the light source 22s and light receiving elements 22r in another arrangement example 1 of the optical module 22 of the motor 10 according to this embodiment. In this example, the optical module 22 has a light source 22s arranged in a first region 22a and a plurality of light receiving elements 22r arranged in a second region 22b. By doing so, the optical module 22 is arranged so that at least a part of it overlaps with the first line segment L1 when viewed from the axial direction, which prevents the optical module 22 from tilting and makes it possible to hold it stably.

[0055] <Another example of optical module placement 2> Figure 9 shows another arrangement example 2 of the optical module 22. Figure 9 is a plan view showing the arrangement of the light source 22s and light receiving elements 22r in another arrangement example 2 of the optical module 22 of the motor 10 according to this embodiment. Another arrangement example 2 of the optical module 22 is an example in which the light source 22s and a plurality of light receiving elements 22r are arranged on a first line segment L1. By doing so, the optical module 22 is arranged so that at least a part of it overlaps with the first line segment L1 when viewed from the axial direction, which prevents the optical module 22 from tilting and makes it possible to hold it stably.

[0056] <Other arrangement examples of optical modules 3> Figure 10 shows another arrangement example 3 of the optical module 22. Figure 10 is a plan view showing the arrangement of the light source 22s and the multiple light-receiving elements 22r in another arrangement example 3 of the optical module 22 of the motor 10 according to this embodiment. Another arrangement example 3 of the optical module 22 is an example in which the light source 22s and the light-receiving elements 22r are arranged on the first line segment L1. By doing so, the optical module 22 is arranged so that at least a part of it overlaps with the first line segment L1 when viewed from the axial direction, which prevents the optical module 22 from tilting and makes it possible to hold it stably.

[0057] <Variation 1> Modified arrangements of the optical module 22 and its surrounding elements in this embodiment are described below. More specifically, an example is described in which the light receiving element 22r receives light Lb emitted from the light source 22s and transmitted through the rotating plate 21.

[0058] Figure 11 is a schematic cross-sectional view showing the relationship between the arrangement of the optical module 22, the substrate 23, and the rotating plate 21 in Modification 1 of the motor 10 according to this embodiment. In Modification 1, the light source 22s is fixed to the optical module 22, and the light receiving element 22r is fixed to the bracket 11. Light Lb emitted from the light source 22s passes through the 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 rotation speed and rotation angle of the rotating plate 21 by reading the pattern obtained when the light Lb passes through the pattern 21p.

[0059] <Variation 2> Figure 12 is a schematic cross-sectional view showing the arrangement of the optical module 22, substrate 23, and rotating plate 21 in Modification 2 of the motor 10 according to this embodiment. In Modification 2, 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 the 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 rotation speed and rotation angle of the rotating plate 21 by reading the pattern obtained when the light Lb passes through the pattern 21p.

[0060] Embodiment 2 Embodiment 2 of this disclosure will now be described. This embodiment differs from Embodiment 1 in the arrangement of the optical module 22 and other components on the substrate 23. Other configurations are the same as in Embodiment 1. The differences from Embodiment 1 will be mainly described below.

[0061] Figure 4 is a schematic diagram of the substrate 23 as seen from the rotating plate 21 in the motor 10 according to this embodiment. As shown in Figure 4, when viewed from the axial direction, the optical module 22 is positioned on the first line segment L1, but it is not positioned at a location that coincides with the midpoint M of the first line segment L1. Also, 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 positioned at a location that coincides with the midpoint M of the first line segment L1 when viewed from the axial direction, and even if the center point of the optical module 22 is not located on the first line segment L1, it is still possible to obtain the effects of this disclosure.

[0062] Furthermore, the first mounting holes 23a to the third mounting holes 23c are positioned in a rotationally symmetrical manner around the rotation axis of the rotating plate 21. More specifically, the first mounting holes 23a to the third mounting holes 23c are arranged concentrically around the axis of the shaft 12 and are spaced equally apart (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]

[0063] This disclosure can be used for encoders and motors equipped therewith. [Explanation of Symbols]

[0064] 10: Motor 11: Bracket 11a: Recess 12: Shaft 13: Bearings 14: Screw 15: Rotor 16: Status 17: Case 20: Encoder 21: Rotating plate 22: Optical Module 22a: 1st area 22b:Second area 22r: Photodetector 22s: light source 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: Internal dimensions D2: External dimensions D3: Interior dimensions D4: External dimensions D5: External dimensions D6: Internal dimensions D7: Interior dimensions L1: First line segment L2: Second line segment L3: Third line segment M: Midpoint

Claims

1. A rotating plate that rotates around an axis of rotation, An optical module comprising at least one of a light source that irradiates light onto the rotating plate and a light-receiving element that receives the light reflected by the rotating plate or the light transmitted through the rotating plate, A substrate on which the optical module is arranged, The system comprises a frame that supports the substrate, The substrate has a first mounting hole and a second mounting hole, and is screwed to the frame by a first screw inserted into the first mounting hole and a second screw inserted into the second mounting hole. In an encoder, the optical module is positioned on a first line segment connecting the center of the first mounting hole and the center of the second mounting hole, as viewed from a direction along the rotation axis. The substrate further has a third mounting hole, When the substrate is viewed along the axis of rotation, the first line segment, the second line segment connecting the center of the first mounting hole and the center of the third mounting hole, and the third line segment connecting the center of the second mounting hole and the center of the third mounting hole form a triangle in which the base angle is larger than the vertex angle and the first line segment is the base. Encoder.

2. Viewed from a direction along the rotation axis, the optical module is substantially rectangular and divided into a first region and a second region by the first line segment. The encoder according to claim 1, wherein the ratio of the area of ​​the first region to the area of ​​the second region is 1:1 to 1:

2.

3. The encoder according to claim 2, wherein the ratio of the area of ​​the first region to the area of ​​the second region is 1:

1.

4. The encoder according to claim 1, wherein, when viewed from a direction along the rotation axis, the optical module is positioned to coincide with the midpoint of the first line segment.

5. The encoder according to claim 1, wherein the triangle constitutes an isosceles triangle with the first line segment as its base.

6. A rotating plate that rotates around a rotation axis, An optical module comprising at least one of a light source that irradiates light onto the rotating plate and a light-receiving element that receives the light reflected by the rotating plate or the light transmitted through the rotating plate, A substrate on which the optical module is arranged, The system comprises a frame that supports the substrate, The substrate has a first mounting hole and a second mounting hole, and is screwed to the frame by a first screw inserted into the first mounting hole and a second screw inserted into the second mounting hole, in an encoder, Viewed from a direction along the rotation axis, the optical module is positioned on a first line segment connecting the center of the first mounting hole and the center of the second mounting hole. The frame houses the rotating plate and has three through holes provided at positions corresponding to the first to third mounting holes, through which the screws are inserted. Encoder.

7. The encoder according to claim 6, wherein, in the radial direction of the rotating plate, the difference between the inner dimension of the frame and the outer dimension of the rotating plate is greater than the difference between the inner dimension of the three through holes and the outer dimension of the screw shaft.

8. A rotating plate that rotates around a rotation axis, An optical module comprising at least one of a light source that irradiates light onto the rotating plate and a light-receiving element that receives the light reflected by the rotating plate or the light transmitted through the rotating plate, A substrate on which the optical module is arranged, The system comprises a frame that supports the substrate, The substrate has a first mounting hole and a second mounting hole, and is screwed to the frame by a first screw inserted into the first mounting hole and a second screw inserted into the second mounting hole. In an encoder, the optical module is positioned on a first line segment connecting the center of the first mounting hole and the center of the second mounting hole, as viewed from a direction along the rotation axis. 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 is greater than the difference between the inner dimensions of the first and second mounting holes and the outer dimensions of the screw shafts. Encoder.

9. Bracket and A shaft passing through the aforementioned bracket, An encoder according to any one of claims 1, 6, or 8, Equipped with, The shaft is attached to the rotating plate and rotates together with the rotating plate. The motor is fixed to the bracket with screws, together with the frame, on the circuit board.

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