Encoder

Abstract

This encoder (10) is an optical battery-less encoder that detects the rotation of a shaft (80) about a rotation axis (A). The encoder (10) comprises: a fixing screw (30) that is screwed into a screw hole (82) formed in an end surface of the shaft (80); a magnet (40) disposed on the fixing screw (30); and a magnetic sensor (64) that generates power using the magnetic field generated by the magnet (40). The fixing screw (30) has: a screw part (32) that is screwed into the screw hole (82); and a head part (31) that is connected to the screw part (32) and has an arrangement part (34) in which the magnet (40) is disposed.

Description

Encoder

[0001] The present disclosure relates to encoders.

[0002] Conventionally, there has been known an optical battery-less encoder that uses an annular magnet that rotates around a rotation axis, a power generating element including a magnetic wire and a coil, a light source, and a light receiving element (see, for example, Patent Document 1). In the optical battery-less encoder described in Patent Document 1, a magnetic field generated by the rotating magnet is used to generate electricity in a power generating element such as a Wiegand wire sensor.

[0003] U.S. Patent No. 9,528,856

[0004] However, in optical battery-less encoders, there is a demand for more efficient use of the magnetic field generated by the magnet.

[0005] An object of the present disclosure is to provide an optical battery-less encoder that can efficiently utilize the magnetic field generated by a magnet.

[0006] An encoder according to one aspect of the present disclosure is an optical, battery-less encoder that detects rotation of a shaft about its rotation axis. The encoder according to one aspect of the present disclosure includes a light source that emits light, a rotating plate that rotates with the shaft and generates modulated light by modulating the light, and a light-receiving element that receives the modulated light. The encoder also includes a fixing screw that is threaded into a threaded hole formed in the end face of the shaft, a support member that is fixed to the shaft by the fixing screw and supports the rotating plate, a magnet disposed on the fixing screw, and a magnetic sensor that generates power using the magnetic field generated by the magnet. The fixing screw has a threaded portion that is threaded into the screw hole and a head that is connected to the threaded portion and has a mounting portion in which the magnet is disposed.

[0007] The present disclosure can provide an optical battery-less encoder that can efficiently utilize the magnetic field generated by a magnet.

[0008] 1 is a cross-sectional view showing the overall configuration of an encoder according to embodiment 1. FIG. 2 is an exploded perspective view showing the overall configuration of an encoder according to embodiment 1. FIG. 3 is a plan view showing the configuration of a magnet and a fixing screw according to embodiment 1. FIG. 4 is a schematic view showing an example of the configuration of a magnetic sensor according to embodiment 1. FIG. 5 is a perspective view showing the configuration of a fixing screw and a magnet according to embodiment 2. FIG. 6 is a plan view showing the configuration of a fixing screw according to embodiment 2. FIG. 7 is a cross-sectional view showing the configuration of a fixing screw according to embodiment 2. FIG. 8 is a plan view showing the configuration of a magnet according to variation 1 of embodiment 2. FIG. 9 is a plan view showing the configuration of a fixing screw according to variation 2 of embodiment 2. FIG. 10 is a cross-sectional view showing the configuration of a fixing screw according to variation 2 of embodiment 2.

[0009] Hereinafter, embodiments of the present disclosure will be described. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the superordinate concept of the present disclosure will be described as optional components.

[0010] Furthermore, each drawing is a schematic diagram and is not necessarily a precise illustration. In each drawing, substantially the same components are denoted by the same reference numerals, and redundant explanations will be omitted or simplified.

[0011] Furthermore, in this specification, terms indicating the relationship between elements, such as perpendicular and parallel, and terms indicating the shape of elements, such as polygon, regular hexagon, ring, rectangle, columnar, and disk-like, are not expressions that only express a strict meaning, but also expressions that include a range of substantial equivalence, for example, a difference of about a few percent.

[0012] First Embodiment An encoder 10 according to a first embodiment will be described.

[0013] [1-1. Overall Configuration] The overall configuration of an encoder 10 according to this embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a cross-sectional view showing the overall configuration of an encoder 10 according to this embodiment. Fig. 1 also shows a shaft 80 to which the encoder 10 is attached. Fig. 1 shows a cross section including a rotation axis A, which is the center of rotation of the shaft 80. Fig. 2 is an exploded perspective view showing the overall configuration of the encoder 10 according to this embodiment.

[0014] The encoder 10 according to this embodiment is an optical, battery-less type encoder that detects rotation of a shaft 80 shown in FIG. 1 about a rotation axis A.

[0015] As shown in FIG. 1, the encoder 10 includes a support member 20, a rotating plate 24, a fixing screw 30, a magnet 40, a frame 50, a mounting board 60, a magnetic sensor 64, a control circuit 76, a light source 71, a light receiving element 72, and a screw 90.

[0016] The shaft 80 is a columnar member that rotates about the rotation axis A. In the present embodiment, the shaft 80 has a cylindrical shape. The shaft 80 may be, for example, the rotation axis of a motor. The encoder 10 may also include the shaft 80 as a component. A threaded hole 82 is formed in the end face (in other words, the bottom face) of the shaft 80. The threaded hole 82 is formed from the end face of the shaft 80 along the rotation axis A. A fixing screw 30 is screwed into the threaded hole 82 along the rotation axis A.

[0017] The support member 20 is a member that supports the rotating plate 24. The support member 20 is fixed to the shaft 80 by a fixing screw 30. In this embodiment, the support member 20 has an annular shape and an annular flat portion. The rotating plate 24 is disposed on the annular flat portion of the support member 20. A through hole 22 is formed in the center of the support member 20. The diameter of the through hole 22 is smaller than the diameter of the end face of the shaft 80 and larger than the diameter of the threaded portion 32 of the fixing screw 30. The threaded portion 32 of the fixing screw 30 inserted into the through hole 22 of the support member 20 is screwed into the threaded hole 82 of the shaft 80. The support member 20 is sandwiched between the head 31 of the fixing screw 30 and the end face of the shaft 80, thereby fixing the support member 20 to the shaft 80. In this manner, the support member 20 is fixed to the shaft 80 by the fixing screw 30 disposed on the rotation axis A. This makes it possible to reduce the dimension of the support member 20 in the direction along the rotation axis A compared to when the support member 20 is fixed to the shaft 80 using a set screw or the like that is screwed into the shaft 80 in a direction perpendicular to the rotation axis A. Therefore, the encoder 10 can be made thinner.

[0018] Furthermore, when screwing the fixing screw 30 into the shaft 80, the fixing screw 30 can be accessed from the direction of the rotation axis A. For example, if the support member 20 is placed inside a cylindrical case, and if a set screw or the like is used to fix the support member 20 to the shaft 80 in a direction perpendicular to the rotation axis A, the case gets in the way and makes it difficult to screw in the set screw. On the other hand, in this embodiment, the support member 20 and the fixing screw 30 can be accessed from the opening of the case, making it easy to assemble the support member 20 and the fixing screw 30.

[0019] The support member 20 fixed to the shaft 80 in the above manner rotates around the rotation axis A together with the shaft 80 .

[0020] The rotating plate 24 supported by the support member 20 rotates together with the shaft 80 and generates modulated light by modulating the light emitted by the light source 71. In this embodiment, the rotating plate 24 has an annular shape centered on the rotation axis A. The reflectance at the position on the rotating plate 24 where the light is incident is modulated according to the position in the circumferential direction of the rotating plate 24. In other words, the rotating plate 24 is a reflective rotating plate. The rotating plate 24 emits reflected light where the intensity of the incident light is modulated. This reflected light is an example of modulated light generated by the rotating plate 24. Note that the rotating plate 24 may also be a transmissive rotating plate in which the transmittance at the position where the light is incident is modulated according to the position in the circumferential direction of the rotating plate 24. When the rotating plate 24 is a transmissive rotating plate, the transmitted light that passes through the rotating plate 24 can be used as modulated light.

[0021] The light source 71 is an element that emits light. In the present embodiment, the light emitted by the light source 71 is incident on the rotating plate 24. In the present embodiment, the light source 71 is mounted on the mounting substrate 60. As the light source 71, for example, an LED (Light Emitting Diode) or the like can be used.

[0022] The light receiving element 72 is an element that receives modulated light generated by the rotating plate 24. In this embodiment, the light receiving element 72 is mounted on the mounting substrate 60. As the light receiving element 72, for example, a photodiode can be used.

[0023] The fixing screw 30 is a member that is screwed into a screw hole 82 formed in the end face of the shaft 80. The fixing screw 30 has a threaded portion 32 that is screwed into the screw hole 82, and a head 31 that is connected to the threaded portion 32 and has a placement portion 34 in which the magnet 40 is placed. The central axis of the threaded portion 32 coincides with the rotation axis A. As a result, the threaded portion 32 of the fixing screw 30 rotates around the rotation axis A together with the shaft 80. In this embodiment, the placement portion 34 is a recess that is recessed in a direction along the rotation axis A. The placement portion 34 is placed in an area that includes the rotation axis A. As a result, the magnet 40 can be accurately placed on the rotation axis A.

[0024] The magnet 40 is a magnetic member that is disposed on the fixing screw 30. More specifically, the magnet 40 is disposed in the disposition portion 34 of the fixing screw 30. The magnet 40 has a north pole 41 and a south pole 42. In this embodiment, the magnet 40 also has a protrusion 44 that protrudes along the rotation axis A in a direction away from the fixing screw 30.

[0025] The shapes of the magnet 40 and the fixing screw 30 will be described with reference to FIG. 3 . FIG. 3 is a plan view showing the configuration of the magnet 40 and the fixing screw 30 according to this embodiment. FIG. 3 shows a plan view of the magnet 40 and the fixing screw 30 as viewed from a direction along the rotation axis A. As shown in FIG. 3 , the magnet 40 is placed in the placement portion 34 of the fixing screw 30. In this embodiment, the placement portion 34 is a recess that is recessed in a direction along the rotation axis A, and at least a portion of the magnet 40 is inserted into the recessed placement portion 34. The magnet 40 may also be fitted into the recessed placement portion 34. This allows the magnet 40 to be accurately positioned at a predetermined position. As shown in FIG. 3 , when viewed from a direction along the rotation axis A, the center or center of gravity of the magnet 40 may be located on the rotation axis A. When viewed from a direction along the rotation axis A, the center or center of gravity of the protrusion 44 of the magnet 40 may also be located on the rotation axis A. The magnet 40 may be fixed to the fixing screw 30 using a joining member such as an adhesive.

[0026] 3 , when viewed in a direction along the rotation axis A, the head 31 of the fixing screw 30 has two parallel sides LS31, LS32 and two parallel sides LL31, LL32. This allows the fixing screw 30 to be easily screwed into the threaded hole 82 of the shaft 80 using a tool or the like that matches the shape of the head 31.

[0027] Furthermore, when viewed from the direction along the rotation axis A, the shape of the magnet 40 is rectangular with two short sides LS41, LS42 and two long sides LL41, LL42, and the two short sides LS41, LS42 respectively face the two sides LS31, LS32 of the head 31. This makes it possible to maximize the dimensions of the long sides LL41, LL42 of the magnet 40 without making them larger than the dimensions of the head 31 of the fixing screw 30.

[0028] Furthermore, the length of the two long sides LL41, LL42 of magnet 40 is equal to or less than the distance between two sides LS31, LS32. This makes it possible to position magnet 40 relative to fixing screw 30 so that magnet 40 does not protrude from two sides LS31, LS32 of fixing screw 30 when viewed in the direction along rotation axis A. This makes it possible to easily rotate fixing screw 30 using a jig or the like that matches the shape of head 31.

[0029] Furthermore, when viewed from the direction along the rotation axis A, the magnet 40 may be disposed inside the outer edge of the head 31 of the fixing screw 30. This allows the fixing screw 30 to be rotated using a general-purpose tool such as a socket wrench.

[0030] The magnetic sensor 64 is a power generating element that generates power using the magnetic field generated by the magnet 40. The magnetic sensor 64 does not rotate together with the shaft 80 or the like. In this embodiment, the magnetic sensor 64 is mounted on a mounting board 60 and arranged on the rotation axis A, as shown in FIGS. 1 and 2 . For example, if the shaft 80 is the rotation axis of the motor, the magnetic sensor 64 is fixed to the main body of the motor via the mounting board 60 and the frame 50. The magnetic sensor 64 is not particularly limited as long as it is a power generating element that generates power using the magnetic field generated by the magnet 40. In this embodiment, the magnetic sensor 64 is a Wiegand wire sensor. The configuration of the magnetic sensor 64 according to this embodiment will be described with reference to FIG. 4.

[0031] 4 is a schematic diagram showing an example of the configuration of a magnetic sensor 64 according to this embodiment. As shown in FIG. 4, the magnetic sensor 64 has a magnetic member 65 and a coil 66. The magnetic member 65 is a Wiegand wire that generates the large Barkhausen effect in response to a change in an external magnetic field. In this embodiment, the magnetic member 65 is disposed on the rotation axis A and extends in a direction perpendicular to the rotation axis A. The coil 66 is a conducting wire wound around the magnetic member 65.

[0032] The Wiegand wire is a magnetic material whose magnetization aligns to one side of the longitudinal direction when a magnetic field of a predetermined magnitude or greater is applied along the length of the Wiegand wire. When the direction of the magnetic flux flowing along the length of the Wiegand wire changes, the magnetization direction of the Wiegand wire suddenly reverses, inducing a voltage pulse across both ends of the coil 66 wound around the Wiegand wire. In this way, the magnetic sensor 64 generates electricity, and the output of the magnetic sensor 64 changes in response to the change in the direction of the magnetic field caused by the rotation of the magnet 40 in the magnetic sensor 64.

[0033] The magnetic sensor 64 may have, for example, a magnetic flux collector. The magnetic flux collector is made of a soft magnetic material such as ferrite and is disposed near both ends of the magnetic member 65. The magnetic flux collector has, for example, an annular shape and surrounds the end or the vicinity of the end of the magnetic member 65.

[0034] The mounting substrate 60 is a substrate on which the magnetic sensor 64 and other components are mounted. In this embodiment, the mounting substrate 60 is a disk-shaped substrate and has a first main surface 60a, a second main surface 60b, three through holes 67, and two through holes 68 (see FIG. 2 ). The first main surface 60a is the main surface on which the magnetic sensor 64 is disposed. The second main surface 60b is the surface behind the first main surface 60a and faces the rotating plate 24 and the frame 50. The control circuit 76, the light source 71, and the light receiving element 72 are disposed on the second main surface 60b. The through holes 67 are holes into which screws 90 are inserted. The through holes 68 are holes into which protrusions 58 formed on the frame 50 are inserted. The mounting substrate 60 is fixed to the frame 50 using screws 90 or the like. For example, if the shaft 80 is a rotating shaft of a motor, the screws 90 are threaded into threaded holes formed in the body of the motor. This fixes the mounting board 60 to the main body of the motor.

[0035] The control circuit 76 is a circuit that detects the rotation of the shaft 80 by controlling the light source 71 etc. The control circuit 76 operates using the power generated by the magnetic sensor 64.

[0036] The frame 50 is a component on which the mounting substrate 60 is disposed. For example, when the shaft 80 is the rotation axis of the motor, the frame 50 is fixed to the main body of the motor. In this embodiment, the frame 50 has three through holes 57 and two protrusions 58. Screws 90 are inserted into the through holes 57. The protrusions 58 protrude toward the mounting substrate 60 and are inserted into the through holes 68 of the mounting substrate 60. The protrusions 58 and the through holes 68 can be used to position the mounting substrate 60 relative to the frame 50.

[0037] [1-2. Effects] The effects of the encoder 10 according to this embodiment will be described.

[0038] As described above, the encoder 10 according to this embodiment has the fixing screw 30 that is screwed into the threaded hole 82 formed in the end face of the shaft 80 that rotates about the rotation axis A. The head 31 of the fixing screw 30 has the arrangement portion 34 in which the magnet 40 is arranged.

[0039] This makes it possible for the set screw 30 to rotate about the rotation axis A. By arranging the magnet 40 in the arrangement portion 34 formed on the head 31 of such a set screw 30, the magnet 40 can be easily arranged on the rotation axis A of the shaft 80. Therefore, for example, when the magnetic sensor 64 is arranged on the rotation axis A, the strength of the magnetic field at the magnetic sensor 64 can be increased. In other words, the encoder 10 according to this embodiment can efficiently utilize the magnetic field generated by the magnet 40. Furthermore, by forming the arrangement portion 34 on a member having a relatively simple structure such as the set screw 30, processing is easier than when forming an arrangement portion on a member having a relatively complex structure such as the support member 20.

[0040] Furthermore, by arranging the magnet 40 on the fixing screw 30, it is possible to reduce adhesion of the adhesive used to join the magnet 40 to the rotating plate 24 compared to when the magnet 40 is arranged on the support member 20, etc. Therefore, the encoder 10 according to this embodiment can reduce the obstruction of the light modulation effect of the rotating plate 24.

[0041] In the encoder 10 according to this embodiment, when viewed from the direction along the rotation axis A, the end edge of the head 31 of the fixing screw 30 has two parallel sides LS31, LS32 and two parallel sides LL31, LL32.

[0042] This allows the fixing screw 30 to be easily screwed into the screw hole 82 of the shaft 80 using a jig or the like that matches the shape of the head 31.

[0043] In the encoder 10 according to this embodiment, the magnet 40 has a rectangular shape having two short sides LS41 and LS42 and two long sides LL41 and LL42 when viewed in a direction along the rotation axis A. The two short sides LS41 and LS42 face the two sides LS31 and LS32 of the head 31 of the fixing screw 30, respectively.

[0044] This allows the dimensions of the long sides LL41 and LL42 of the magnet 40 to be increased to the maximum extent possible without exceeding the dimensions of the head 31 of the fixing screw 30.

[0045] In the encoder 10 according to this embodiment, the length of the two long sides LL41 and LL42 of the magnet 40 is equal to or less than the distance between the two sides LS31 and LS32 of the head 31 of the fixing screw 30.

[0046] This makes it possible to position the magnet 40 relative to the fixing screw 30 so that the magnet 40 does not protrude from the two sides LS31, LS32 of the fixing screw 30 when viewed in the direction along the rotation axis A. This makes it possible to easily rotate the fixing screw 30 using a jig or the like that matches the shape of the head 31.

[0047] In the encoder 10 according to this embodiment, when viewed in the direction along the rotation axis A, the magnet 40 is disposed inside the outer edge of the head 31 of the fixing screw 30 .

[0048] This allows the fixing screw 30 to be rotated using a general-purpose tool such as a socket wrench.

[0049] In the encoder 10 according to this embodiment, the magnetic sensor 64 is disposed on the axis A of rotation.

[0050] This makes it possible to maximize the strength of the magnetic field generated by the magnet 40 in the magnetic sensor 64. In other words, the encoder 10 according to this embodiment can efficiently utilize the magnetic field generated by the magnet 40.

[0051] In the encoder 10 according to this embodiment, the magnetic sensor 64 has a magnetic member 65 that generates a large Barkhausen effect in response to a change in an external magnetic field.

[0052] This allows the magnetic sensor 64 to be a Wiegand wire sensor, so that even when the rotation frequency of the magnetic field generated by the magnet 40 fixed to the shaft 80 is low, the magnetic sensor 64 can output a high voltage.

[0053] (Embodiment 2) An encoder according to embodiment 2 will be described. The encoder according to this embodiment differs from the fixing screw 30 and magnet 40 of the encoder 10 according to embodiment 1 mainly in the configuration of the fixing screw 130 and magnet 140. The encoder according to this embodiment will be described below with reference to Figures 5 to 7, focusing on the differences from the encoder 10 according to embodiment 1.

[0054] Fig. 5 is a perspective view showing the configuration of the fixing screw 130 and magnet 140 according to this embodiment. Figs. 6 and 7 are a plan view and a cross-sectional view, respectively, showing the configuration of the fixing screw 130 according to this embodiment. In Fig. 6, the outline of the magnet 140 placed on the fixing screw 130 is shown by a dashed line. Fig. 7 shows a cross section of the fixing screw 130 taken along line VII-VII shown in Fig. 6.

[0055] 5 to 7, the encoder according to this embodiment includes a fixing screw 130 and a magnet 140. The fixing screw 130 according to this embodiment has a threaded portion 132 and a head portion 131 connected to the threaded portion 132 and having an arrangement portion 134 on which the magnet 140 is arranged. The threaded portion 132 has a configuration similar to that of the threaded portion 32 according to the first embodiment.

[0056] 6 , in the fixing screw 130 according to the present embodiment, as in the fixing screw 30 according to the first embodiment, the outline of the head 131 of the fixing screw 130 has two parallel sides LS131 and LS132 when viewed in the direction along the rotation axis A. More specifically, the shape of the head 131 of the fixing screw 130 is a regular hexagon when viewed in the direction along the rotation axis A. This allows the threaded portion 132 of the fixing screw 130 to be easily screwed into the threaded hole 82 of the shaft 80 using a general-purpose tool such as a hexagonal wrench.

[0057] 7 , the arrangement portion 134 of the fixing screw 130 is a recess that is recessed in a direction along the rotation axis A, and at least one end of the recess extends to an end of the head 131 when viewed from the direction along the rotation axis A. This allows the arrangement portion 134, which is a recess, to be easily formed by a construction method such as header machining. In this embodiment, both longitudinal ends of the recess extend to the ends of the head 131.

[0058] 6 , when viewed from the direction along the rotation axis A, the shape of the magnet 140 is rectangular with two short sides LS141, LS142 and two long sides LL141, LL142. In this embodiment, the length of the two long sides LL141, LL142 is greater than the distance between the two sides LS131, LS132 of the fixing screw 130. In this way, when viewed from the direction along the rotation axis A, the longitudinal dimension of the magnet 140 may be greater than the dimension of the head 131 of the fixing screw 130. This allows the volume of the magnet 140 to be increased, thereby increasing the strength of the magnetic field generated by the magnet 140.

[0059] In the present embodiment, the length of the two long sides LL141, LL142 of magnet 140, as viewed in the direction along rotation axis A, is greater than the distance between two sides LS131, LS132 of fixing screw 130; however, the dimensions of the magnet according to the present disclosure are not limited to this. For example, the length of the two long sides of the magnet according to the present disclosure, as viewed in the direction along rotation axis A, may be less than the distance between two sides LS131, LS132 of fixing screw 130. An example configuration of such a magnet according to the present disclosure will be described using FIG. 8 . FIG. 8 is a plan view showing the configuration of magnet 240 according to Variation 1 of the present embodiment. In FIG. 8 , the outline of magnet 240 is shown by a dashed line, and fixing screw 130 is shown by a solid line.

[0060] The fixing screw 130 shown in FIG. 8 has the same configuration as the fixing screw 130 according to the present embodiment described above.

[0061] 8, when viewed in a direction along the rotation axis A, the magnet 240 according to the first modification is rectangular with two short sides LS241 and LS242 and two long sides LL241 and LL242. The two short sides LS241 and LS242 face the two sides LS131 and LS132 of the head 131, respectively.

[0062] The length of the two long sides LL241, LL242 of magnet 240 according to Modification 1 is equal to or less than the distance between two sides LS131, LS132 of fixing screw 130. This makes it possible to position magnet 240 relative to fixing screw 130 so that magnet 240 (its short sides LS241, LS242) does not protrude beyond two sides LS131, LS132 of fixing screw 130 when viewed from the direction along rotation axis A. This makes it possible to easily rotate fixing screw 130 using a jig or the like that matches the shape of head 131.

[0063] Furthermore, in the fixation screw 130 according to the present embodiment, the arrangement portion 134 is a recess recessed in a direction along the rotation axis A, and both ends of the recess extend to the end of the head 131 of the fixation screw 130 as viewed along the rotation axis A. However, the configuration of the fixation screw according to the present disclosure is not limited to this. For example, the arrangement portion of the fixation screw according to the present disclosure may be a recess recessed in a direction along the rotation axis A, and only one end of the recess may extend to the end of the head of the fixation screw according to the present disclosure as viewed along the rotation axis A. Such an example configuration of the fixation screw according to the present disclosure will be described using FIGS. 9 and 10. FIGS. 9 and 10 are, respectively, a plan view and a cross-sectional view showing the configuration of a fixation screw 130a according to Variation 2 of the present embodiment. FIG. 10 shows a cross section of the fixation screw 130a taken along line X-X shown in FIG. 9.

[0064] As shown in Figures 9 and 10, a fixing screw 130a according to the second modification has a threaded portion 132 and a head 131a connected to the threaded portion 132 and having an arrangement portion 134a in which a magnet 240 or the like is arranged.

[0065] The arrangement portion 134a is a recess that is recessed in a direction along the rotation axis A, and only one of the two longitudinal ends of the recess extends to the end of the head 131a when viewed in the direction along the rotation axis A. The arrangement portion 134a of the fixing screw 130a according to the second modification having such a configuration can also be easily formed by a method such as header machining, similar to the arrangement portion 134 of the fixing screw 130 according to the present embodiment.

[0066] (Other Embodiments, etc.) While the encoder according to the present disclosure has been described above based on the embodiments, the present disclosure is not limited to the above embodiments. The present disclosure also includes embodiments obtained by applying various modifications to the above embodiments that would occur to those skilled in the art, and embodiments realized by arbitrarily combining the components and functions of the embodiments within the scope of the present disclosure.

[0067] For example, although the mounting portions 34, 134, 134a of the fixing screws 30, 130, 130a in the above-described embodiments are recessed portions, the configuration of the mounting portions is not limited to this. For example, the mounting portions may be protruding portions that protrude along the rotation axis A, and the magnet may be formed with a recess into which the protruding portions are inserted.

[0068] Furthermore, in the second embodiment, the shape of the head 131 of the fixing screw 130 is a regular hexagon when viewed in a direction along the rotation axis A, but the shape of the head 131 is not limited to this. The shape of the head of the fixing screw may also be a polygon when viewed in a direction along the rotation axis A. Even with such a fixing screw, the fixing screw can be easily rotated using a jig or the like that matches the shape of the head of the fixing screw.

[0069] Although the magnetic sensor 64 according to each of the above embodiments includes a Wiegand wire, the configuration of the magnetic sensor is not limited to this. For example, the magnetic sensor may be a coil without a Wiegand wire.

[0070] [Summary] Below, examples of the contents disclosed in this specification will be given, and the effects and the like obtained from the contents of the disclosure will be described.

[0071] [Example 1] Encoder 10 is an optical, battery-less encoder that detects rotation of shaft 80 about rotation axis A. Encoder 10 includes a light source 71 that emits light, a rotating plate 24 that rotates with shaft 80 and generates modulated light by modulating the light, and a light-receiving element 72 that receives the modulated light. Encoder 10 also includes a fixing screw 30, 130, or 130a that is screwed into a threaded hole 82 formed in the end face of shaft 80, and a support member 20 that is fixed to shaft 80 by fixing screw 30, 130, or 130a and supports rotating plate 24. Encoder 10 also includes a magnet 40, 140, or 240 that is disposed in fixing screw 30, 130, or 130a, and a magnetic sensor 64 that generates power using the magnetic field generated by magnet 40, 140, or 240. The fixing screw 30, 130, or 130a has a threaded portion 32 or 132 that is screwed into the screw hole 82, and a head 31, 131, or 131a that is connected to the threaded portion 32 or 132 and has an arrangement portion 34, 134, or 134a in which the magnet 40, 140, or 240 is arranged.

[0072] This allows the set screw 30, 130, or 130a to rotate about the rotation axis A. By arranging the magnet 40, 140, or 240 in the arrangement portion 34, 134, or 134a formed on the head 31, 131, or 131a of the set screw 30, 130, or 130a, the magnet 40, 140, or 240 can be easily arranged on the rotation axis A of the shaft 80. Therefore, for example, when the magnetic sensor 64 is arranged on the rotation axis A, the strength of the magnetic field at the magnetic sensor 64 can be increased. In other words, the magnetic field generated by the magnet 40, 140, or 240 can be efficiently utilized. Furthermore, forming the arrangement portion 34, 134, or 134a on a member having a relatively simple structure, such as the set screw 30, 130, or 130a, makes processing easier than forming an arrangement portion on a member having a relatively complex structure, such as the support member 20.

[0073] Furthermore, by arranging the magnet 40, 140, or 240 on the fixing screw 30, 130, or 130a, it is possible to reduce adhesion of the adhesive used to join the magnet 40, 140, or 240 to the rotating plate 24 compared to when the magnet 40, 140, or 240 is arranged on the support member 20, etc. Therefore, it is possible to reduce the obstruction of the light modulation effect of the rotating plate 24.

[0074] [Example 2] The arrangement portion 134 or 134a is a recess that is recessed in a direction along the rotation axis A, and when viewed from the direction along the rotation axis A, at least one end of the recess extends to the end of the head 131 or 131a.

[0075] This allows the placement portion 134 or 134a, which is a recess, to be easily formed by a construction method such as header processing. The configuration of Example 2 is applicable to Example 1.

[0076] [Example 3] When viewed from the direction along the rotation axis A, the end edge of the head 31, 131, or 131a has two parallel sides LS31, LS32, two parallel sides LL31, LL32, or two parallel sides LS131, LS132.

[0077] This allows the fixing screw 30, 130, or 130a to be easily screwed into the screw hole 82 of the shaft 80 using a jig or the like that matches the shape of the head 31, 131, or 131a. The configuration of Example 3 can be applied to Example 1 or Example 2.

[0078] [Example 4] When viewed from the direction along the rotation axis A, the shape of the magnet 40, 140, or 240 is a rectangle having two short sides LS41 and LS42, two short sides LS141 and LS142, or two short sides LS241 and LS242, and two long sides LL41 and LL42, two long sides LL141 and LL142, or two long sides LL241 and LL242. Furthermore, the two short sides LS41 and LS42, the two short sides LS141 and LS142, or the two short sides LS241 and LS242 face the two sides LS31 and LS32, or the two sides LS131 and LS132, of the head 31, 131, or 131a, respectively.

[0079] This allows the dimensions of the long sides LL41, LL42 or long sides LL241, LL242 of the magnet 40 or 240 to be increased to the maximum extent possible without exceeding the dimensions of the head 31, 131, or 131 a of the fixing screw 30, 130, or 130 a. The configuration of Example 4 is applicable to Example 3.

[0080] [Example 5] The length of the two long sides LL41 and LL42 or the two long sides LL241 and LL242 is equal to or less than the distance between the two sides LS31 and LS32 or the distance between the two sides LS131 and LS132.

[0081] This makes it possible to position the magnet 40 or 240 relative to the fastening screw 30, 130, or 130a so that the magnet 40 or 240 does not protrude from two sides LS31, LS32 or two sides LS131, LS132 of the fastening screw 30, 130, or 130a when viewed from the direction along the rotation axis A. This makes it possible to easily rotate the fastening screw 30, 130, or 130a using a jig or the like that matches the shape of the head 31, 131, or 131a. The configuration of Example 5 can be applied to Example 4.

[0082] [Example 6] When viewed from the direction along the rotation axis A, the shape of the head 131 or 131a is polygonal.

[0083] This allows the fixing screw 130 or 130a to be easily screwed into the screw hole 82 of the shaft 80 using a jig or the like that matches the shape of the head 131 or 131a. The configuration of Example 6 can be applied to any of Examples 1 to 5.

[0084] [Example 7] When viewed from the direction along the rotation axis A, the shape of the head 131 or 131a is a regular hexagon.

[0085] This allows the fixing screw 130 or 130a to be easily screwed into the screw hole 82 of the shaft 80 using a general-purpose tool such as a hex wrench. The configuration of Example 7 can be applied to any of Examples 1 to 6.

[0086] [Example 8] When viewed in the direction along the rotation axis A, the magnet 40 or 240 is arranged inside the outer edge of the head 31, 131, or 131a.

[0087] This allows the fixing screw 30, 130, or 130a to be rotated using a general-purpose tool such as a socket wrench. The configuration of Example 8 can be applied to any of Examples 1 to 7.

[0088] [Example 9] The magnetic sensor 64 is arranged on the axis of rotation A.

[0089] This maximizes the strength of the magnetic field generated by the magnet 40, 140, or 240 in the magnetic sensor 64. In other words, it is possible to efficiently utilize the magnetic field generated by the magnet 40, 140, or 240. The configuration of Example 9 can be applied to any of Examples 1 to 8.

[0090] [Example 10] The magnetic sensor 64 has a magnetic member 65 that generates the large Barkhausen effect in response to a change in an external magnetic field.

[0091] This allows the magnetic sensor 64 to be a Wiegand wire sensor, so that the magnetic sensor 64 can output a high voltage even when the rotation frequency of the magnetic field generated by the magnet 40, 140, or 240 fixed to the shaft 80 is low. The configuration of Example 10 can be applied to any of Examples 1 to 9.

[0092] An encoder according to the present disclosure can be used, for example, as a detector that detects the rotation of a rotating shaft of a motor or the like.

[0093] 10 Encoder 20 Support member 22, 57, 67, 68 Through hole 24 Rotating plate 30, 130, 130a Fixing screw 31, 131, 131a Head 32, 132 Threaded portion 34, 134, 134a Arrangement portion 40, 140, 240 Magnet 41 North pole 42 South pole 44 Protrusion 50 Frame 58 Protrusion 60 Mounting board 60a First main surface 60b Second main surface 64 Magnetic sensor 65 Magnetic member 66 Coil 71 Light source 72 Light receiving element 76 Control circuit 80 Shaft 82 Screw hole 90 Screw A Rotation axis LL41, LL42, LL141, LL142, LL241, LL242 Long side LS31, LS32, LL31, LL32, LS131, LS132 Side LS41, LS42, LS141, LS142, LS241, LS242 Short Side

Claims

1. An optical battery-less type encoder that detects rotation about the rotation axis of a shaft, comprising: a light source that emits light; a rotating plate that rotates with the shaft and generates modulated light by modulating the light; a light receiving element that receives the modulated light; a fixing screw that is screwed into a screw hole formed in an end face of the shaft; a support member that is fixed to the shaft by the fixing screw and supports the rotating plate; a magnet disposed on the fixing screw; and a magnetic sensor that generates electricity using the magnetic field generated by the magnet, wherein the fixing screw has a threaded portion that is screwed into the screw hole, and a head that is connected to the threaded portion and has a positioning portion on which the magnet is disposed.

2. The encoder according to claim 1, wherein the arrangement portion is a recess that is recessed in a direction along the rotation axis, and at least one end of the recess extends to an end of the head when viewed from the direction along the rotation axis.

3. The encoder according to claim 1 or 2, wherein an edge of the head has two sides that are parallel to each other when viewed from a direction along the rotation axis.

4. The encoder according to claim 3, wherein the magnet has a rectangular shape having two short sides and two long sides when viewed from a direction along the axis of rotation, and the two short sides each face the two sides of the head.

5. The encoder according to claim 4, wherein the lengths of the two long sides are equal to or less than the distance between the two sides.

6. The encoder according to claim 1 or 2, wherein the shape of the head is polygonal when viewed from a direction along the rotation axis.

7. The encoder according to claim 6, wherein the shape of the head is a regular hexagon when viewed from a direction along the rotation axis.

8. The encoder according to claim 1 or 2, wherein the magnet is disposed inside an outer edge of the head when viewed in a direction along the rotation axis.

9. The encoder according to claim 1 or 2, wherein the magnetic sensor is disposed on the axis of rotation.

10. The encoder according to claim 1 or 2, wherein the magnetic sensor has a magnetic member that produces a large Barkhausen effect in response to a change in an external magnetic field.

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