Magnetic detection device and absolute encoder

Abstract

The present application can easily assemble a shield member having different thicknesses. A magnetic detection device (60) is provided with a magnet (Mr) after magnetization, an angle sensor (Sr) that is a magnetic sensor that senses magnetic flux from the magnet (Mr), a magnet holder (61) that holds the magnet (Mr), and a second lay shaft gear shaft (62). There are a housing (4) that has a plurality of outer wall portions (4a) and a cover portion (4b) that houses the magnet (Mr) and the magnetic sensor (Sr) on the inside, and a flat plate-shaped shield member (7) that has a shape corresponding to the cover portion (4b) and is assembled to the cover portion (4b). The shield member (7) has a protrusion (77) that protrudes outward from an outer peripheral portion (731a), and the housing (4) has a recess (4e) that opens to the inside to accommodate the protrusion (77) at an end portion on the outside of the cover portion (4b). The recess (4e) has a plurality of side wall portions (41e) that differ in width and a plurality of upper wall portions (42e) that differ in height.

Description

Technical Field

[0001] This invention relates to a magnetic detection device and an absolute encoder. Background Technology

[0002] In the past, magnetic detection devices, which sense magnetic flux from magnets (magnetic bodies) using magnetic sensors, have been used in various technologies. Magnetic detection devices are also used in rotary encoders used to detect the position and angle of movable elements in various control mechanisms. Rotary encoders include incremental encoders that detect relative position or angle and absolute encoders that detect absolute position or angle. Among such absolute encoders are those equipped with magnetic detection devices. As an absolute encoder equipped with a magnetic detection device, a magnetic encoder device is known. This device assembles a magnetized magnet onto a rotating shaft (main shaft) that is the object of measurement, and detects the rotation angle of the magnet using a magnetic sensor, thereby detecting the amount of rotation of the main shaft that is the object of measurement. Furthermore, a method is known to determine the amount of rotation of the main shaft after multiple rotations by acquiring the rotation angle of a rotating body that decelerates as the main shaft rotates.

[0003] To maintain the resolution of the determinable spindle rotation amount in such an absolute encoder and to expand the range of determinable spindle rotation amounts, a structure has been proposed that detects the rotation amount of multiple magnets by means of magnetic sensors acting as angle sensors corresponding to multiple magnets. For example, a structure has been proposed in which the spindle is connected to the secondary shaft or a subsequent shaft by means of a reduction mechanism, and the rotation amount of the magnets mounted on each shaft is detected by means of magnetic sensors corresponding to the magnets mounted on each shaft, thereby determining the rotation amount of the spindle (for example, see Patent Document 1). Existing technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-15536 Summary of the Invention The problem that the invention aims to solve

[0005] In absolute encoders that detect the rotation of a magnet, the magnetic flux sensed by the magnetic sensor changes periodically as the rotating shaft rotates. The rotation of the shaft is detected based on this change in magnetic flux within a predetermined rotation period. Therefore, some of the magnetic flux generated by external devices can affect the magnetic sensor, which is the magnetic sensing element. Consequently, the detection accuracy can sometimes deteriorate due to noise from external factors other than the magnetic flux from the permanent magnet that is intended to be detected. Therefore, in absolute encoders, to prevent magnetic flux from external devices from affecting the magnetic sensor, a magnetic shielding member formed by magnetic components is sometimes provided on the outside of the housing. However, in absolute encoders, the required shielding performance of the magnetic shielding components varies depending on the operating environment and the required specifications. The shielding performance of the magnetic shielding components can be changed by altering the thickness of the components. Therefore, it is desirable to easily assemble multiple shielding components with different shielding properties.

[0006] The present invention was made in view of the above-mentioned problems, and its object is to provide a magnetic detection device and an absolute encoder that can be easily assembled with shielding components of different thicknesses. Solution for solving the problem

[0007] To achieve the above objectives, the magnetic detection device of the present invention comprises: a magnetized magnet; a magnetic sensor for sensing magnetic flux from the magnet; a magnet holder for holding the magnet; a shaft; a housing having multiple sidewall portions and an upper surface portion for internally accommodating the magnet and the magnetic sensor; and a flat shielding member having a shape corresponding to the upper surface portion and being fitted onto the upper surface portion, the shielding member having a protrusion protruding outward from the outer periphery, and the housing having an inwardly opening recess at the outer end of the upper surface portion for accommodating the protrusion, the recess having multiple sidewall portions of different widths and multiple upper wall portions of different heights.

[0008] In one embodiment of the magnetic detection device of the present invention, the height of the plurality of upper wall portions is set according to the height of the protrusions of the plurality of shielding members with different plate thicknesses, and the width of the plurality of side wall portions is set according to the width of the protrusions of the plurality of shielding members with different plate thicknesses.

[0009] In one aspect of the magnetic detection device of the present invention, the housing has a recess forming portion that protrudes upward from the outer end of the upper surface portion to form the recess, and the shielding member has an outer surface portion facing the recess forming portion on the outer side of the convex portion in the width direction.

[0010] In one aspect of the magnetic detection device of the present invention, the housing has a boss portion protruding upward from the upper surface portion, and the shielding member has a boss hole for receiving the boss portion.

[0011] In one aspect of the magnetic detection device of the present invention, the shielding member has: a curved portion, the outer periphery of which is curved along the sidewall portion of the housing on the side opposite to the location where the protrusion is provided; and a through hole formed on the curved portion, the housing having a threaded hole, the threaded hole communicating with the through hole on the sidewall portion opposite to the location where the recess is provided.

[0012] To achieve the above objectives, the absolute encoder of the present invention is characterized by having the magnetic detection device of the present invention. Invention Effects

[0013] The magnetic detection device and absolute encoder according to the present invention can easily assemble shielding components of different thicknesses. Attached Figure Description

[0014] Figure 1 This is a perspective view that schematically illustrates the configuration of an absolute encoder according to an embodiment of the present invention. Figure 2 This is a general representation of the state after removing the casing and shielding. Figure 1 The diagram shows a three-dimensional representation of the structure of an absolute encoder. Figure 3 This is a general representation of the state after removing the substrate, connectors, and support plate. Figure 2 The diagram shows a three-dimensional representation of the structure of an absolute encoder. Figure 4 It is a general representation of observation from other perspectives. Figure 3 A three-dimensional diagram showing the configuration of an absolute encoder. Figure 5 This is a general representation of the state of the motor. Figure 3 The diagram shows a three-dimensional representation of the structure of an absolute encoder. Figure 6 It is a general representation Figure 5 The diagram shows a top view of the structure of an absolute encoder. Figure 7 This indicates cutting along a surface parallel to the central axis of the principal axis. Figure 1 The cross-sectional view shown shows the state of the absolute encoder. Figure 8 It is a general representation. Figure 1 The absolute encoder shown is a cross-sectional view of the state in which the motor is removed, cut along a plane passing through the central axis of the main shaft gear and orthogonal to the central axis of the first intermediate gear. Figure 9 It is a general representation Figure 8 An exploded longitudinal section view of the components of the absolute encoder shown, including the magnet, spindle gear, spindle connector, and motor spindle. Figure 10 It means Figure 8 An enlarged sectional view of one end of the spindle connector shown. Figure 11 It is a general representation. Figure 6 The diagram shows a cross-sectional view of the absolute encoder configuration, cut along a plane that passes through the central axis of the first intermediate gear and is parallel to the XY plane. Figure 12 Observing from other angles Figure 11 An enlarged perspective view of the sectional view shown. Figure 13 It is a general representation. Figure 6The diagram shows a partial cross-sectional view of the absolute encoder configuration, cut along a plane that passes through the central axis of the first intermediate gear and is orthogonal to the XY plane. Figure 14 It is a general representation. Figure 12 The diagram shown is an exploded perspective view of the absolute encoder, with the base, first intermediate gear, first intermediate gear shaft, leaf spring, and screws disassembled. Figure 15 It is a general representation. Figure 2 The diagram shows a partial cross-sectional view of the absolute encoder configuration, cut along a plane that passes through the central axis of the first secondary gear and is orthogonal to the central axis of the first intermediate gear. Figure 16 It is a general representation. Figure 15 The diagram shown is an exploded perspective view of the absolute encoder, with the magnet, magnet holder, first counterspindle gear, and bearing disassembled. Figure 17 It is a general representation. Figure 2 The diagram shows a partial cross-sectional view of the absolute encoder configuration, cut along the plane passing through the central axis of the second intermediate gear and the second counterspindle gear. Figure 18 It is Figure 17 The enlarged cross-sectional view of the second intermediate gear shown. Figure 19 It is to have Figure 17 An enlarged sectional view of the magnet retainer of the second auxiliary shaft gear shown. Figure 20 It is a general representation of... Figure 19 The image shown is an exploded perspective view of the magnet holder in its disassembled state. Figure 21 It means that it can serve as Figure 19 The diagram shows a schematic perspective view of a cylindrical magnet suitable for use with a magnet holder. Figure 22 It means Figure 18 An enlarged sectional view of one end of the lower side of the second auxiliary shaft gear shaft shown. Figure 23 This is a schematic diagram showing the second auxiliary shaft gear shaft being pressed into the shaft support portion of the base. Figure 24 This is a schematic diagram showing the second auxiliary shaft gear shaft being pressed into the shaft support portion of the base. Figure 25 This is a diagram illustrating a modified example of a support protrusion at the main shaft side end that supports the first intermediate gear shaft in an absolute encoder. Figure 26This is a diagram illustrating a modified example of a support protrusion at the main shaft side end that supports the first intermediate gear shaft in an absolute encoder. Figure 27 This is a diagram illustrating a modified example of a support protrusion at the main shaft side end that supports the first intermediate gear shaft in an absolute encoder. Figure 28 Viewed from the lower surface side Figure 2 The diagram shows the substrate. Figure 29 It is a general representation Figure 1 The diagram shows the functional structure of an absolute encoder. Figure 30 It is a three-dimensional diagram that roughly represents the structure of the housing and shielding components of an absolute encoder. Figure 31 It is a top view that roughly represents the structure of the shielding components of an absolute encoder. Figure 32 This is a side view taken along the X-axis, which is a general representation of the housing structure of an absolute encoder. Figure 33 It is a cross-sectional view taken along the Y-axis, which is a rough representation of the structure of the shell. Figure 34 This is a schematic diagram showing the situation where the protrusion of the shielding member is inserted into the recess of the housing of the absolute encoder. Figure 35 This is a three-dimensional diagram that roughly represents the configuration of an absolute encoder with another shielding component. Figure 36 This is a schematic diagram showing the situation where the protrusion of another shielding member is inserted into the recess of the housing of the absolute encoder. Figure 37 This is a top view that roughly represents the configuration of another shielding component of an absolute encoder. Figure 38 This is a top view that roughly represents the configuration of another shielding component of an absolute encoder. Figure 39 This is a schematic diagram showing the situation where the protrusion of another shielding member is inserted into the recess of the housing of the absolute encoder. Figure 40 This is a three-dimensional diagram that roughly represents the configuration of an absolute encoder with another shielding component. Figure 41 This is a perspective view that schematically illustrates the configuration of an absolute encoder as a modified embodiment of the present invention. Detailed Implementation

[0015] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the dimensions of the components in each drawing are shown at appropriate enlargements or reductions for ease of understanding. Furthermore, in each drawing, parts of components that are not important in explaining the embodiments of the present invention are omitted. Additionally, gears are shown in the drawings with their tooth shapes omitted. Furthermore, although terms including ordinal numbers such as first and second are used to describe various constituent elements, these terms are used only for the purpose of distinguishing one constituent element from others, and the constituent elements are not limited by these terms. It should be noted that the present invention is not limited to this embodiment.

[0016] The magnetic detection device 60 according to an embodiment of the present invention includes: a magnetized magnet Mr; an angle sensor Sr, a magnetic sensor that senses magnetic flux from the magnet Mr; a magnet holder 61 that holds the magnet Mr; and a second counterspindle gear shaft 62 serving as a shaft. The magnet holder 61 is rotatably supported by the second counterspindle gear shaft 62. The second counterspindle gear shaft 62 is formed of a magnetic material, and an attractive force generated by magnetic force is generated between the magnet Mr and the second counterspindle gear shaft 62 in the direction of the rotation axis of the magnet holder 61. Furthermore, the absolute encoder 2 according to an embodiment of the present invention includes the magnetic detection device 60 according to the embodiment of the present invention described above. Hereinafter, the structures of the absolute encoder 2 and the magnetic detection device 60 will be specifically described.

[0017] Figure 1 This is a perspective view that schematically illustrates the configuration of the absolute encoder 2 according to an embodiment of the present invention. Figure 2 This is represented by the state after removing the housing 4 and the shielding. Figure 1 A three-dimensional diagram showing the configuration of the absolute encoder 2. Figure 1 In the diagram, the absolute encoder 2 is shown through its shield, housing 4, and substrate 5. Figure 2 In the middle, it is shown in the form of a substrate 5 through an absolute encoder 2.

[0018] In this description, for convenience, the absolute encoder 2 is based on an XYZ orthogonal coordinate system. The X-axis corresponds to the horizontal left-right direction, the Y-axis corresponds to the horizontal front-back direction, and the Z-axis corresponds to the vertical up-down direction. The Y-axis and Z-axis are orthogonal to the X-axis. In this description, the X-axis is also referred to as the left or right side, the Y-axis as the front or back side, and the Z-axis as the top or bottom side. Figure 1 , Figure 2 In the orientation (upright orientation) of the absolute encoder 2 shown, the left side in the X-axis direction is the left side, and the right side in the X-axis direction is the right side. Furthermore, in Figure 1 , Figure 2In the orientation of the absolute encoder 2 shown, the side in front of the root in the Y-axis direction is the front side, and the side in the depth direction in the Y-axis direction is the rear side. Furthermore, in Figure 1 , Figure 2 In the orientation of the absolute encoder 2 shown, the upper side in the Z-axis direction is called the top side, and the lower side in the Z-axis direction is called the bottom side. The view from the top in the Z-axis direction is called the top view, the view from the front in the Y-axis direction is called the front view, and the view in the X-axis direction is called the side view. This orientation representation does not limit the usage orientation of the absolute encoder 2; the absolute encoder 2 can be used in any orientation.

[0019] As described above, the absolute encoder 2 is an absolute encoder that determines and outputs the amount of rotation of the main shaft 1a of the motor 1 after multiple rotations. In an embodiment of the present invention, the absolute encoder 2 is located at the upper end of the motor 1 in the Z-axis direction. In an embodiment of the present invention, the absolute encoder 2 has a generally rectangular shape when viewed from above, and a horizontally elongated rectangular shape that is thin in the vertical direction, which is the extension direction of the main shaft 1a, when viewed from the front and side. That is, the absolute encoder 2 has a flat cuboid shape that is longer in the horizontal direction than in the vertical direction.

[0020] The absolute encoder 2 includes a housing 4 that houses the internal structure. The housing 4 has multiple (e.g., four) outer wall portions 4a that surround at least a portion of the main shaft 1a of the motor 1, the main shaft gear 10, the first intermediate gear 20, the first counter-shaft gear 30, the second intermediate gear 70, and the magnet retainer 61. Furthermore, the housing 4 has a cover 4b that blocks the openings on the upper sides of the four outer wall portions 4a. The cover 4b is covered by a shielding member.

[0021] As an example, motor 1 can be a stepper motor or a DC brushless motor. As another example, motor 1 can be a motor used as a drive source for industrial robots, etc., to drive via a reduction mechanism such as a wave gear device. The vertical sides of the main shaft 1a of motor 1 protrude from the motor housing. The absolute encoder 2 outputs the rotation amount of the main shaft 1a of motor 1 as a digital signal.

[0022] The motor 1 has a roughly rectangular shape when viewed from above, and also a roughly rectangular shape in the vertical direction. That is, the motor 1 has a roughly cubic shape. The length of each of the four outer walls constituting the shape of the motor 1 when viewed from above is, for example, 25 mm, meaning the shape of the motor 1 is a 25 mm quadrilateral when viewed from above. Furthermore, the absolute encoder 2, provided on the motor 1, matches the shape of the motor 1 and is, for example, a 25 mm quadrilateral when viewed from above.

[0023] like Figure 1 , Figure 2As shown, the substrate 5 is configured to cover the interior of the absolute encoder 2 together with the housing 4. The substrate 5 has a generally rectangular shape when viewed from above and is a thin, plate-like printed circuit board in the vertical direction. Furthermore, a connector 6 is connected to the substrate 5; the connector 6 is a component for connecting the absolute encoder 2 to an external device (not shown).

[0024] Figure 3 This is a rough representation of the state after removing substrate 5 and connector 6. Figure 2 The diagram shows a three-dimensional representation of the structure of the absolute encoder 2. Figure 4 It is a general representation of observation from other perspectives. Figure 3 The diagram shows a three-dimensional view of the configuration of the absolute encoder 2. Figure 5 This is a general representation of the state of removing motor 1. Figure 3 The diagram shows a three-dimensional representation of the structure of the absolute encoder 2. Figure 6 It is a general representation Figure 5 The top view showing the configuration of the absolute encoder 2.

[0025] The absolute encoder 2 includes: a main shaft gear 10 having a first worm portion 11 (first drive gear); a first intermediate gear 20 having a first worm wheel portion 21 (first driven gear) and a second worm portion 22 (second drive gear); a first countershaft gear 30 having a second worm wheel portion 31 (second driven gear) and a gear portion 32 (third drive gear); a second intermediate gear 70; a magnet holder 61 having a second countershaft gear 63; a magnet Mp; an angle sensor Sp corresponding to the magnet Mp; a magnet Mq; an angle sensor Sq corresponding to the magnet Mq; a magnet Mr; an angle sensor Sr corresponding to the magnet Mr; and a microcomputer 51.

[0026] The main shaft 1a of motor 1 is the output shaft of motor 1 and the input shaft that transmits rotational force to absolute encoder 2. Main shaft gear 10 is fixed to the main shaft 1a of motor 1 and is rotatably supported integrally with the main shaft 1a by the bearing members of motor 1. A first worm gear portion 11 is disposed on the outer periphery of the main shaft gear 10 such that it rotates with the rotation of the main shaft 1a of motor 1. In the main shaft gear 10, the central axis of the first worm gear portion 11 is aligned with or substantially aligned with the central axis of the main shaft 1a. A first worm wheel portion 21 is disposed on the outer periphery of the first intermediate gear 20, and is configured to mesh with the first worm gear portion 11 and rotate with the rotation of the first worm gear portion 11. The axial angle between the first worm wheel portion 21 and the first worm gear portion 11 is set to 90° or approximately 90°.

[0027] There is no particular limitation on the outer diameter of the first worm gear portion 21, but in the illustrated example, the outer diameter of the first worm gear portion 21 is set to be smaller than the outer diameter of the first worm portion 11 (see reference). Figure 8The outer diameter of the first worm gear section 21 is relatively small. As a result, the vertical dimension of the absolute encoder 2 is minimized.

[0028] The second worm gear portion 22 is disposed on the outer periphery of the first intermediate gear 20 and rotates with the rotation of the first worm wheel portion 21. In the first intermediate gear 20, the central axis of the second worm gear portion 22 is aligned with or substantially aligned with the central axis of the first worm wheel portion 21. The second worm wheel portion 31 is disposed on the outer periphery of the first counterspindle gear 30 and is configured to mesh with the second worm gear portion 22, rotating with the rotation of the second worm gear portion 22. The axial angle between the second worm wheel portion 31 and the second worm gear portion 22 is set to 90° or substantially 90°. The axis of rotation of the second worm wheel portion 31 is set to be parallel or substantially parallel to the axis of rotation of the first worm gear portion 11. The gear portion 32 is disposed on the outer periphery of the first counterspindle gear 30 and rotates with the rotation of the second worm wheel portion 31. In the first counterspindle gear 30, the central axis of the gear portion 32 is aligned with or substantially aligned with the central axis of the second worm wheel portion 31.

[0029] Here, the direction in which the first worm gear 21 faces the first worm shaft 11 for meshing with the first worm portion 21 is defined as the first meshing direction. Figure 12 (The direction of arrow P1). Similarly, for the second worm portion 22 to mesh with the second worm wheel portion 31, the direction of the second worm portion 22 toward the second worm wheel portion 31 is defined as the second meshing direction ( Figure 12 (The direction of arrow P2). In this embodiment, both the first meshing direction P1 and the second meshing direction P2 are along the horizontal plane (XY plane).

[0030] The second intermediate gear 70 has a gear portion 71 (third driven gear) and a gear portion 72 (fourth drive gear). The gear portion 71 is located on the outer periphery of the second intermediate gear 70 and meshes with the gear portion 32 of the first counterspindle gear 30, rotating as the gear portion 32 rotates. The gear portion 72 is located on the outer periphery of the second intermediate gear 70 and rotates as the gear portion 71 rotates. In the second intermediate gear 70, the gear portion 72 is configured such that its central axis coincides with or is substantially coincident with the central axis of the gear portion 71. The rotation axes of the gear portions 71 and 72 are configured to be parallel or substantially parallel to the rotation axis of the gear portion 32 of the first counterspindle gear 30.

[0031] The magnet retainer 61 has a second counterspindle gear 63, which, as described later, has a gear portion 64 (fourth driven gear) disposed on the second counterspindle gear 63. The gear portion 64 is disposed on the outer periphery of the second counterspindle gear 63 and meshes with the gear portion 72 of the second intermediate gear 70, rotating as the gear portion 72 rotates. The axis of rotation of the gear portion 64 is set to be parallel or substantially parallel to the axis of rotation of the gear portion 72 of the second intermediate gear 70.

[0032] An angle sensor Sq senses the rotation angle of the second worm gear 31, i.e., the rotation angle of the first counterspindle gear 30. A magnet Mq is fixed on the upper surface of the first counterspindle gear 30 such that the central axes of both are aligned or substantially aligned. The magnet Mq has two magnetic poles arranged in a direction perpendicular or substantially perpendicular to the rotation axis of the first counterspindle gear 30. The angle sensor Sq is positioned with its lower surface separated by a gap and opposed vertically to the upper surface of the magnet Mq, for sensing the rotation angle of the first counterspindle gear 30.

[0033] As an example, the angle sensor Sq is fixed to the substrate 5, which is supported by the substrate support 110 of the base 3 (described later) disposed on the absolute encoder 2. The angle sensor Sq senses the magnetic flux of the magnet Mq and outputs the sensing information to the microcomputer 51. The microcomputer 51 determines the rotation angle of the magnet Mq, i.e., the rotation angle of the first secondary shaft gear 30, based on the input sensing information related to the magnetic flux.

[0034] An angle sensor Sr senses the rotation angle of the magnet holder 61, i.e., the rotation angle of the second counterspindle gear 63. The magnet Mr is fixed to the upper surface of the second counterspindle gear 63 such that their central axes coincide or are approximately coincident. The magnet Mr has two magnetic poles arranged in a direction perpendicular to the rotation axis of the second counterspindle gear 63. The angle sensor Sr is configured such that its lower surface, separated by a gap, is opposed to the upper surface of the magnet Mr in the vertical direction, for sensing the rotation angle of the second counterspindle gear 63.

[0035] As an example, the angle sensor Sr is fixed to the substrate 5 on the same surface as the fixed angle sensor Sq, on which the angle sensor Sq is fixed. The angle sensor Sr senses the magnetic flux of the magnet Mr and outputs the sensing information to the microcomputer 51. The microcomputer 51 determines the rotation angle of the magnet Mr, i.e., the rotation angle of the second counterspindle gear 63, based on the input sensing information related to the magnetic flux.

[0036] The magnet Mp is fixed on the upper surface of the spindle gear 10 such that the central axes of both are aligned or substantially aligned. The magnet Mp has two magnetic poles arranged in a direction perpendicular to the rotation axis of the spindle gear 10. An angle sensor Sp is configured such that its lower surface is positioned opposite the upper surface of the magnet Mp in the vertical direction with a gap between them, and is used to sense the rotation angle of the spindle gear 10.

[0037] As an example, angle sensor Sp is fixed to substrate 5 on the same surface as fixed angle sensor Sq, on which angle sensor Sq is also fixed. Angle sensor Sp senses the magnetic flux of magnet Mp and outputs the sensing information to microcomputer 51. Microcomputer 51 determines the rotation angle of magnet Mp based on the input sensing information related to magnetic flux, thereby determining the rotation angle of spindle gear 10, that is, the rotation angle of spindle 1a. The resolution of the rotation angle of spindle 1a corresponds to the resolution of angle sensor Sp. As described later, microcomputer 51 determines the rotation amount of spindle 1a based on the determined rotation angles of first secondary shaft gear 30, second secondary shaft gear 63, and spindle 1a, and outputs this value. Alternatively, microcomputer 51 may output the rotation amount of spindle 1a of motor 1 as a digital signal.

[0038] The absolute encoder 2 configured in this way can determine the rotational speed of the main shaft 1a based on the rotational angle of the first counterspindle gear 30 determined based on the sensing information of the angle sensor Sq and the rotational angle of the second counterspindle gear 63 determined based on the sensing information of the angle sensor Sr, and determine the rotational angle of the main shaft 1a based on the sensing information of the angle sensor Sp. Furthermore, the microcomputer 51 determines the amount of rotation of the main shaft 1a after multiple rotations based on the determined number of rotations of the main shaft 1a and the rotational angle of the main shaft 1a.

[0039] The number of teeth in the first worm gear 11 of the main shaft gear 10 on the main shaft 1a is, for example, 5, and the number of teeth in the first worm wheel 21 is, for example, 20. That is, the first worm gear 11 and the first worm wheel 21 constitute a first transmission mechanism R1 with a reduction ratio of 20 / 5 = 4 (see reference). Figure 6 When the first worm gear 11 rotates 4 times, the first worm wheel 21 rotates 1 time. The first worm wheel 21 and the second worm gear 22 are mounted on the same axis to form the first intermediate gear 20, which rotates as a whole. Therefore, when the first worm gear 11 rotates 4 times, that is, when the main shaft 1a and the main shaft gear 10 rotate 4 times, the first intermediate gear 20 rotates 1 time, and the second worm gear 22 rotates 1 time.

[0040] The number of teeth in the second worm gear section 22 is, for example, 2, and the number of teeth in the second worm wheel section 31 of the first countershaft gear 30 is, for example, 25. That is, the second worm gear section 22 and the second worm wheel section 31 constitute a second transmission mechanism R2 with a reduction ratio of 25 / 2 = 12.5 (see reference). Figure 6 When the second worm gear 22 rotates 12.5 revolutions, the second worm wheel 31 rotates 1 revolution. The first counterspindle gear 30, on which the second worm wheel 31 is formed, rotates integrally with the magnet holder 35 and the magnet Mq as described later. Therefore, when the second worm gear 22, which constitutes the first intermediate gear 20, rotates 12.5 revolutions, the magnet Mq rotates 1 revolution.

[0041] The first counterspindle gear 30 has, for example, 18 teeth in its gear section 32, and the second intermediate gear 70 has, for example, 36 teeth in its gear section 71. That is, gear section 32 and gear section 71 constitute a third transmission mechanism R3 with a reduction ratio of 36 / 18 = 2 (see reference). Figure 5 When the gear section 32 of the first countershaft gear 30 rotates 2 revolutions, the gear section 71 of the second intermediate gear 70 rotates 1 revolution. Furthermore, the number of teeth in the gear section 72 of the second intermediate gear 70 is, for example, 19, and the number of teeth in the gear section 64 of the second countershaft gear 63 is, for example, 38. That is to say, gear section 64 and gear section 72 constitute a fourth transmission mechanism R4 with a reduction ratio of 38 / 19 = 2 (see reference). Figure 5 When the gear section 72 of the second intermediate gear 70 rotates 2 revolutions, the gear section 64 of the second countershaft gear 63 rotates 1 revolution.

[0042] Gear section 71 and gear section 72 are mounted coaxially to form the second intermediate gear 70, rotating integrally. Therefore, when gear section 71 rotates one revolution, gear section 72 rotates one revolution. Thus, the reduction ratio in the entire second intermediate gear 70 is 4. That is, when gear section 32 of the first countershaft gear 30 rotates four revolutions, the second intermediate gear 70 rotates two revolutions, and gear section 64 of the second countershaft gear 63 rotates one revolution. The second countershaft gear 63, on which gear section 64 is formed, constitutes the magnet retainer 61 as described later, rotating integrally with the magnet Mr. Therefore, when gear section 32 constituting the first countershaft gear 30 rotates four revolutions, the magnet Mr rotates one revolution.

[0043] In summary, when the main shaft 1a rotates 200 revolutions, the first intermediate gear 20 rotates 50 revolutions, the first counter-shaft gear 30 and magnet Mq rotate 4 revolutions, the second intermediate gear 70 rotates 2 revolutions, and the second counter-shaft gear 63 and magnet Mr rotate 1 revolution. That is, the rotational speed of the main shaft 1a rotating 50 revolutions can be determined based on sensing information related to the rotational angle of the first counter-shaft gear 30 with angle sensor Sq, and the rotational speed of the main shaft 1a rotating 200 revolutions can be determined based on sensing information related to the rotational angle of the second counter-shaft gear 63 with angle sensor Sr. Furthermore, the reduction speed of the first counter-shaft gear 30 relative to the main shaft gear 10 is smaller than that of the second counter-shaft gear 63, and the resolution of the rotational amount of the main shaft 1a based on the sensing information of the magnetic sensor Sq is higher than the resolution of the rotational amount of the main shaft 1a based on the sensing information of the magnetic sensor Sr, wherein the magnetic sensor Sq corresponds to the magnet Mq rotating with the first counter-shaft gear 30, and the magnetic sensor Sr corresponds to the magnet Mr rotating with the second counter-shaft gear 63. Therefore, in the absolute encoder 2, the range of the rotation amount of the spindle 1a that can be determined can be amplified without reducing the resolution of the rotation amount of the spindle 1a that can be determined.

[0044] The following is a detailed explanation of the structure of the absolute encoder 2.

[0045] As described above (refer to) Figures 1-6 The absolute encoder 2 includes a base 3, a housing 4, a base plate 5, and a connector 6. Furthermore, the absolute encoder 2 includes a main shaft gear 10, a first intermediate gear 20, a first counter-shaft gear 30, a second intermediate gear 70, a magnet holder 61 with a second counter-shaft gear 63, and a force application mechanism 40. In addition, the absolute encoder 2 includes magnets Mp, Mq, Mr and angle sensors Sp, Sq, Sr, and a microcomputer 51 for controlling the drive unit, detection unit, etc., of the absolute encoder 2.

[0046] The base 3 is a platform that holds the main shaft gear 10, the first intermediate gear 20, the first counter-shaft gear 30, the second intermediate gear 70, the magnet holder 61 (second counter-shaft gear 63), and other rotating bodies in a rotatable manner, and fixes the base plate 5, the force application mechanism 40, and other components. Figures 3-6 , Figures 11-14 As shown, the base 3 has a base 101 and various support portions provided on the base 101 for supporting the components of the absolute encoder 2, as described later. Figure 7 As shown, the housing 4 is fixed to the base 3 via a support plate 3a. The support plate 3a is clamped between the base 3 and the motor 1, and the housing 4 is fixed to the support plate 3a at one location, for example, by a screw 8c. Furthermore, in the base 3, the base plate 5 is fixed at three locations, for example, by screws 8a. The base 101 is a plate-shaped portion having two opposite sides facing the absolute encoder 2 in the vertical direction, extending in the horizontal direction (X-axis and Y-axis directions).

[0047] The upper surface 104 of the surface that serves as the upper side of the base 101 is provided with substrate support pillars 110 and substrate positioning pins 120, which serve as a part for supporting the substrate 5. The base 3, for example, has three substrate support pillars 110 and two substrate positioning pins 120.

[0048] like Figure 5 As shown, the substrate support 110 is a portion protruding upward from the upper surface 104 of the base 101, and is, for example, cylindrical or substantially cylindrical. A threaded hole 112 extending downward is formed on the upper end face (upper end face 111) of the substrate support 110. The upper end faces 111 of each substrate support 110 are formed to extend on the same horizontal plane or along the same horizontal plane. In the absolute encoder 2, for the substrate 5, its lower surface 5a is in contact with the upper end face 111 of the substrate support 110 and is fixed to the substrate support 110 by a screw 8a that engages with the threaded hole 112. It should be noted that, as described later, one of the substrate supports 110 is integrated with a substrate positioning pin 120 and a support protrusion 45 constituting the force application mechanism 40 described later. Furthermore, the substrate support 110 may also have a pattern for reinforcement.

[0049] like Figure 5 As shown, the substrate positioning pin 120 is a portion that protrudes upward from the upper surface 104 of the base 101, and is, for example, cylindrical or substantially cylindrical. Compared to the portion lower than the tip portion 121 (base 122), the upper end (tip portion 121) of the substrate positioning pin 120 is thinner, and a stepped surface 123 is formed between the tip portion 121 and the base 122. The tip portion 121 of the substrate positioning pin 120 can be inserted into a device described later, such as... Figure 28 The positioning holes 5b formed on the substrate 5 as shown are used to position the substrate 5 relative to the base 3 by inserting the top end 121 of the substrate positioning pin 120 into the positioning holes 5b of the substrate 5.

[0050] In addition, such as Figure 5 As shown, the base 3 has support protrusions 131, 132, and 141 (see reference) on the upper surface 104 of the base 101, which are upwardly projecting portions. Figures 3-6 (etc.). The support protrusion 132 is the portion that supports the leaf spring 9 that presses the first intermediate gear 20 toward the central axis of the first intermediate gear 20, as described later. The support protrusions 131 and 141 are portions that support the first intermediate gear 20 in a rotatable manner, as described later. In addition, the base 3 has a bearing retainer portion 134 (see below) that supports the bearing 135 that holds the first counterspindle gear 30 in a rotatable manner, as described later. Figure 15 Furthermore, as described below, the base 3 includes: a shaft support portion 137 that supports the second secondary gear shaft 62, which rotatably supports the magnet holder 61 on which the second secondary gear 63 is formed; and a shaft support portion 136 that supports the shaft 75, which rotatably supports the second intermediate gear 70 (see reference). Figures 17-19 Furthermore, a support protrusion 45 is provided on the upper surface 104 of the base 101 of the base 3. The support protrusion 45 is part of the force-applying mechanism 40 that applies force to the second worm gear 22 in the direction of the second worm wheel 31 as described later, and is a part that supports the force-applying spring 41.

[0051] Next, each component supported by the base 3 of the absolute encoder 2 will be described in detail.

[0052] (Spindle gear) Figure 8 It is a general representation. Figure 1 The absolute encoder 2 shown is a cross-sectional view of the state in which the motor 1 is removed, cut along a plane passing through the central axis of the main shaft gear 10 and orthogonal to the central axis of the first intermediate gear 20. Figure 9 It is a general representation Figure 8An exploded longitudinal section view of the structure of the absolute encoder 2, including the magnet Mp, the spindle gear 10, the spindle connector 12, and the spindle 1a of the motor 1.

[0053] like Figure 8 , Figure 9 As shown, the main shaft gear 10 is a cylindrical member coaxially or substantially coaxially disposed with the main shaft 1a and the main shaft connector 12 of the motor 1. The main shaft gear 10 includes a cylindrical portion 13 and a first worm portion 11 located radially outward of the cylindrical portion 13. The first worm portion 11 is the gear portion of the main shaft gear 10. Figure 9 As shown, a cylindrical press-in portion 1b with a space formed on its inner circumference is formed at the upper end of the main shaft 1a of the motor 1. The press-in portion 1b is pressed into the main shaft connector 12 for fixation. In addition, a cylindrical press-in portion 14 with a space formed on its inner side is formed in the cylindrical portion 13 of the main shaft gear 10. The press-in portion 14 is pressed into the main shaft connector 12 for fixation.

[0054] In addition, such as Figure 8 , Figure 9 As shown, a magnet holding portion 15 for holding a magnet Mp is formed in the cylindrical portion 13 of the main shaft gear 10. The magnet holding portion 15 is a portion that forms a recessed portion corresponding to the shape of the magnet Mp, which is recessed downward from the upper end surface 13a of the cylindrical portion 13, and can accommodate the magnet Mp. The magnet holding portion 15 communicates with the pressing portion 14 and has: a cylindrical inner circumferential surface 15a with a diameter larger than that of the pressing portion 14; and an annular bottom surface 15b that connects the inner circumferential surface 15a to the pressing portion 14.

[0055] The inner peripheral surface 15a of the magnet holding portion 15 is formed to contact the outer peripheral surface Mpd of the magnet Mp housed in the magnet holding portion 15. In the absolute encoder 2, the upper end surface 12a of the spindle connector 12 is located above the bottom surface 15b of the magnet holding portion 15. In the absolute encoder 2, the lower surface Mpb of the magnet Mp contacts the upper end surface 12a of the spindle connector 12 but not the bottom surface 15b of the magnet holding portion 15 of the spindle gear 10. Thus, the vertical positioning of the magnet Mp is performed by the upper end surface 12a of the spindle connector 12, and the horizontal positioning is performed by the inner peripheral surface 15a of the magnet holding portion 15. The lower surface Mpb of the magnet Mp, positioned in this way, is bonded and fixed to the upper end surface 12a of the spindle connector 12.

[0056] As described above, the magnet Mp is fixed to the spindle joint 12, and the magnet Mp, the spindle gear 10, and the spindle joint 12 rotate integrally with the spindle 1a of the motor 1. The magnet Mp, the spindle gear 10, and the spindle joint 12 rotate about the same axis as the spindle 1a of the motor 1.

[0057] The first worm gear portion 11 is composed of helical teeth and is configured to mesh with the first worm wheel portion 21 of the first intermediate gear 20. The first worm gear portion 11 is, for example, formed of polyacetal resin. The first worm gear portion 11 is an example of a first drive gear.

[0058] like Figure 9 As shown, the magnet Mp is a disk-shaped or substantially disk-shaped permanent magnet inserted into the magnet holding part 15 of the main shaft gear 10, having an upper surface MPa and a lower surface Mpb facing each other. In the absolute encoder 2, as described above, the position (position in the vertical direction) of the magnet Mp in the direction of the central axis GC1 of the main shaft gear 10 is defined by the upper end face 12a of the main shaft connector 12, such that the upper surface MPa of the magnet Mp faces each other at a certain distance in the vertical direction from the surface of the angle sensor Sp.

[0059] The central axis MpC of magnet Mp (representing the axis at the center of magnet Mp or the axis passing through the center of the magnetic pole boundary) is aligned or substantially aligned with the central axis GC1 of spindle gear 10, the central axis SaC of spindle connector 12, and the central axis MoC of spindle 1a of motor 1. By aligning or substantially aligning the central axes in this way, angle sensor Sp can detect the rotation angle or rotation amount of magnet Mp with higher accuracy.

[0060] It should be noted that, in the embodiments of the present invention, ideally, the two magnetic poles (N / S) of the magnet Mp are formed adjacent to each other in a horizontal plane (XY plane) perpendicular to the central axis MpC of the magnet Mp. This further improves the detection accuracy of the rotation angle or rotation amount of the angle sensor Sp. It should be noted that the magnet Mp is formed, for example, from a ferrite system, an Nd(neodymium)-Fe(iron)-B(boron) system, or other magnetic materials. The magnet Mp can also be, for example, a rubber magnet containing a resin binder, a bonded magnet, etc.

[0061] (Spindle connector) Figure 10 This is an enlarged sectional view showing one end 124 of the spindle connector 12.

[0062] The main shaft connector 12 is a shaft into which the main shaft 1a of the motor 1 and the cylindrical portion 13 of the main shaft gear 10 are pressed as support members into the press-in portions 1b and 14. For example... Figure 8 , Figure 9 as well as Figure 10 As shown, the spindle connector 12 has tapered faces 126 and 127 and a through hole 128.

[0063] A through hole 128 extends through one end 124 and the other end 125 in the spindle joint 12. The through hole 128 has: a first hole portion 128a, occupying a region extending a predetermined length along the axial direction from one end 124; and a second hole portion 128c, occupying a region extending from the first hole portion 128a to the other end 125. In the through hole 128, the diameter of the hole in the first hole portion 128a within the region extending along the axial direction from one end 124 is larger than the diameter of the hole in the second hole portion 128c located at the other end 125. It should be noted that the end portion 128b between the first hole portion 128a and the second hole portion 128c is formed when machining the first hole portion 128a using a drill bit with an angled tip; when machining with an end mill, the end portion 128b is absent.

[0064] The absolute encoder 2 employs a structure in which the main shaft gear 10 is mounted on the main shaft 1a of the motor 1. To accommodate main shafts 1a of various diameters, the main shaft gear 10 is not directly mounted on the main shaft 1a, but is fixed via the main shaft connector 12. Here, the main shaft 1a, being the rotating shaft of the motor, requires rigidity. Furthermore, the main shaft connector 12 needs to be fixed to the magnet Mg using adhesive as described above; therefore, ideally, the main shaft 1a and the main shaft connector 12 should be made of metal. Consequently, a high pressing force is required when pressing the main shaft connector 12 into the pressing portion 1b of the main shaft 1a. In this case, due to the pressing force, damage such as buckling deformation of the main shaft 1a and grinding of the pressing fit (inner diameter portion and outer diameter portion) between the main shaft 1a and the main shaft connector 12 may occur.

[0065] In the absolute encoder 2, by making the diameter of the first hole 128a of the through hole 128 of the spindle connector 12 larger than the diameter of the second hole 128c, the wall thickness is thinned, which makes the spindle connector 12 easier to bend, reduces the pressing force on the spindle 1a, and lightens the load on the spindle 1a. On the other hand, in order to fix the magnet Mp to the upper part (top side) of the spindle connector 12 with adhesive, a contact area with the magnet Mp (the wall thickness between the outer diameter and the inner diameter of the spindle connector 12) is required. Therefore, the spindle connector 12 is configured such that the diameter of the through hole 128 is different in the axial direction with a defined position, for example, a region corresponding to the pressing amount (the size required for pressing) on ​​one end 124 side.

[0066] That is to say, the specific press-in amount of the spindle connector 12 is closer to one end 124 (in Figure 9The diameter of the first hole 128a (located on the lower side) is larger than that of the second hole 128c, which facilitates deformation of the circumferential surface 129 of the spindle connector 12, making it easier to press into the pressing part 1b. Furthermore, by making the diameter of the second hole 128c (located on the upper side in 9) closer to the other end 125 (where the pressing amount is smaller) smaller than that of the first hole 128a, the bonding area with the magnet Mp can be ensured, and the pressing force can be reduced without compromising the bonding retention force.

[0067] The tapered surfaces 126 and 127 are inclined outer peripheral surfaces with diameters smaller than the diameter of the circumferential surface 129 at one end 124 and the other end 125. In the tapered surface 126, the connection portion 126a between the tapered surface 126 of the spindle connector 12 and the outer peripheral surface 129 is connected by a curved surface. In the tapered surface 127 on the other end 125 side, the connection portion 127a between the tapered surface 126 and the outer peripheral surface 129 is also connected by a curved surface. That is, in the tapered surfaces 126 and 127, the connection portions 126a and 127a between the tapered surfaces and the outer peripheral surface 129 are machined with curved surfaces.

[0068] like Figure 9 As shown, a region of a predetermined length from one end 124 along the axial direction of the spindle connector 12 is pressed into a pressing portion 1b formed at the upper end of the spindle 1a of the motor 1. Furthermore, a region of a predetermined length from the other end 125 along the axial direction of the spindle connector 12 is pressed into a pressing portion 14 formed in the cylindrical portion 13 of the spindle gear 10.

[0069] Here, when only the tapered face 126 is chamfered with a straight line, when one end 124 of the spindle connector 12 is pressed into the press-in portion 1b, chips are generated from both the spindle connector 12 and the press-in portion 1b when the edge of the hole in the press-in portion 1b contacts the tapered face 126. Similarly, when only the tapered face 127 is chamfered with a straight line, when the other end 125 of the spindle connector 12 is pressed into the press-in portion 14, chips are generated from both the spindle connector 12 and the press-in portion 14 when the edge of the hole in the press-in portion 14 contacts the tapered face 127.

[0070] On the other hand, when the spindle connector 12 is pressed into the pressing portion 1b and the pressing portion 14, after the tapered surfaces 126 and 127 are inserted into the pressing portions 1b and 14, the connecting portions 126a and 127a of the outer peripheral surfaces between the tapered surfaces 126 and 127 and the peripheral surface 129 come into contact with the pressing portions 1b and 14. By performing surface machining on the connecting portions 126a and 127a of the outer peripheral surfaces between the tapered surfaces 126 and 127 and the peripheral surface 129 of the spindle connector 12, the spindle connector 12 is smoothly pressed into the pressing portions 1b and 14, thus preventing grinding of both the spindle connector 12 and the pressing portions 1b and 14. Therefore, according to the spindle connector 12, the scattering of debris and the like can be suppressed. Furthermore, according to the spindle connector 12, the spindle connector 12 can be prevented from tilting (tilting) due to component grinding and being pressed in. Furthermore, according to the spindle joint 12, the amount of press-in (the required size for press-in) can be reduced by suppressing the tilt of the spindle joint 12.

[0071] Ideally, the curved surfaces of the connecting portions 126a and 127a are machined to a radius of approximately 1 mm. Furthermore, by making the surface roughness of the spindle connector 12, including the circumferential surface 129 and the tapered surfaces 126 and 127 of the connecting portions 126a and 127a, smoother, material abrasion on both the surfaces of the spindle connector 12 and the press-fit portion 14 can be prevented. The surface roughness Rmax (maximum roughness) of the spindle connector 12 is preferably set to 1.6 μm or less, for example. It should be noted that the curved surface machining of the connecting portions 126a and 127a can also be performed on either end 124 or the other end 125.

[0072] (First intermediate gear) Figure 11 It is a general representation. Figure 6 The absolute encoder 2 shown is a cross-sectional view cut along a plane that passes through the central axis of the first intermediate gear 20 and is parallel to the horizontal plane (XY plane). Figure 12 Viewed from above on the side of the secondary shaft end 23b of the first intermediate gear shaft 23. Figure 11 The image shows an enlarged perspective view of the absolute encoder 2 in cross-section. Figure 13 It is a general representation. Figure 6 The diagram shows a partial cross-sectional view of the absolute encoder 2, cut along a plane that passes through the central axis of the first intermediate gear 20 and is orthogonal to the horizontal plane (XY plane).

[0073] like Figures 4-6 and Figures 11-13As shown, the first intermediate gear 20 is supported on the upper side of the base 101 of the base 3 by the first intermediate gear shaft 23 and is rotatable. The first intermediate gear shaft 23 extends parallel to the horizontal plane. Furthermore, the first intermediate gear shaft 23 is not parallel to each of the left-right direction (X-axis direction) and the front-back direction (Y-axis direction) when viewed from above. That is, the first intermediate gear shaft 23 is inclined with respect to each of the left-right direction and the front-back direction. Each inclination of the first intermediate gear shaft 23 with respect to the left-right direction and the front-back direction means that the first intermediate gear shaft 23 extends obliquely with respect to the outer peripheral surfaces 105 to 108 of the base 101 of the base 3 (see reference). Figure 11 In the absolute encoder 2, the first intermediate gear shaft 23 is supported on the base 101 of the base 3 by a support protrusion 131 located on the side of the main shaft gear 10 and a support protrusion 141 located on the side of the first auxiliary shaft gear 30.

[0074] The outer peripheral surface of the base 3 is composed of a left outer peripheral surface 107, a rear outer peripheral surface 106, and a front outer peripheral surface 108. The left outer peripheral surface 107 is parallel to the right outer peripheral surface 105 and the YZ plane. The rear outer peripheral surface 106 and the front outer peripheral surface 108 are parallel to the XZ plane and extend between the right outer peripheral surface 105 and the left outer peripheral surface 107. The right outer peripheral surface 105 is located on the right side (right side in the X-axis direction) of the base 3. The left outer peripheral surface 107 is located on the left side (left side in the X-axis direction) of the base 3. The rear outer peripheral surface 106 is located on the rear side (rear side in the Y-axis direction) of the base 3. The front outer peripheral surface 108 is located on the front side (front side in the Y-axis direction) of the base 3.

[0075] like Figures 3-6 As shown, as an example, the dimensions of the absolute encoder 2, viewed from above, match the dimensions of the 25mm quadrilateral motor 1. Therefore, the first intermediate gear 20, arranged parallel to the upper surface 104 of the base 3, is designed to extend obliquely relative to the outer peripheral surfaces 105 to 108 of the base 3, thereby reducing the horizontal dimension of the absolute encoder 2. It should be noted that the horizontal direction refers to a direction orthogonal to the central axis of the motor 1's main shaft 1a, or a direction parallel to the XY plane.

[0076] like Figure 5 , Figure 6 as well as Figures 11-14As shown, the first intermediate gear 20 is a cylindrical component rotatable about a first intermediate gear shaft 23, comprising a first worm gear portion 21, a second worm portion 22, a cylindrical portion 24, a main shaft-side sliding portion 25, and a secondary shaft-side sliding portion 26. The cylindrical portion 24 is a cylindrically extending component with an inner circumferential surface 24b, which forms a through hole 24a through which the first intermediate gear shaft 23 can be inserted. The through hole 24a is a space enclosed by the inner circumferential surface 24b of the cylindrical portion 24. The inner circumferential surface 24b is configured to slide along the outer circumferential surface of the first intermediate gear shaft 23, which extends into the through hole 24a. The first intermediate gear 20 is supported by the first intermediate gear shaft 23 and can rotate freely about the first intermediate gear shaft 23. The first intermediate gear 20 is a component integrally molded from metal, resin, or the like; here, as an example, it is formed from polyacetal resin.

[0077] like Figures 5-8 As shown, the first worm gear portion 21 is a gear that meshes with the first worm portion 11 of the main shaft gear 10. The first worm gear portion 21 is an example of a first driven gear. The first worm gear portion 21 is provided on one end side of the cylindrical portion 24 of the first intermediate gear 20, and for example, it is composed of a plurality of teeth provided on the cylindrical surface formed on one end side of the cylindrical portion 24 of the first intermediate gear 20. In the absolute encoder 2, the first intermediate gear 20 is provided at a position where the first worm gear portion 21 is located near the center of the base portion 101 of the base 3. Therefore, the end of the cylindrical portion 24 near which the first worm gear portion 21 is provided refers to the end on the main shaft gear 10 side of the first intermediate gear 20.

[0078] like Figure 8 As shown, the outer diameter of the first worm gear portion 21 is smaller than the outer diameter of the first worm portion 11. The central axis of the first worm gear portion 21 is coaxial or substantially coaxial with the central axis of the inner circumferential surface 24b of the cylindrical portion 24. In the absolute encoder 2, the central axis of the first worm gear portion 21 is parallel or substantially parallel to the upper surface 104 of the base portion 101 of the base 3. Therefore, by reducing the outer diameter of the first worm gear portion 21, miniaturization in the vertical direction (height direction) of the absolute encoder 2 can be achieved.

[0079] like Figure 5 , Figure 6 , Figures 11-15As shown, the second worm portion 22 is composed of helical teeth arranged coaxially or substantially coaxially with the first worm gear portion 21. The second worm portion 22 is an example of a second drive gear. Specifically, the second worm portion 22 is provided on the other end side of the cylindrical portion 24, and is composed, for example, of helical teeth provided on the cylindrical surface formed on the other end side of the cylindrical portion 24. The other end side of the cylindrical portion 24 refers to the side of the end that serves as the first countershaft gear 30 of the first intermediate gear 20. Furthermore, the central axis of the second worm portion 22 is coaxial or substantially coaxial with the central axis of the inner circumferential surface 24b of the cylindrical portion 24. The second worm portion 22 meshes with the second worm gear portion 31 provided on the first countershaft gear 30, thereby transmitting the rotational force of the first intermediate gear 20 to the first countershaft gear 30.

[0080] As described above, the axial angle between the first worm portion 11 and the first worm wheel portion 21 is 90° or approximately 90°, and the central axis of the first worm portion 11 and the central axis of the first worm wheel portion 21 are orthogonal or approximately orthogonal when viewed from a direction perpendicular to both the central axes of the first worm portion 11 and the first worm wheel portion 21. Furthermore, the axial angle between the second worm portion 22 and the second worm wheel portion 31 is 90° or approximately 90°, and the central axis of the second worm portion 22 and the central axis of the second worm wheel portion 31 are orthogonal or approximately orthogonal when viewed from a direction perpendicular to both the central axes of the second worm portion 22 and the second worm wheel portion 31.

[0081] like Figure 15 As shown, in order to achieve miniaturization of the absolute encoder 2 in the vertical direction (height direction), the outer diameter of the second worm 22 is set to a small value within the possible range.

[0082] like Figure 6 , Figures 11-13 As shown, the main shaft-side sliding portion 25 of the first intermediate gear 20 is provided at one end of the first intermediate gear 20, that is, at one end serving as the main shaft gear 10 side of the first intermediate gear 20. Specifically, the main shaft-side sliding portion 25 is the end face of one end of the cylindrical portion 24, and is an annular surface formed at one end of the cylindrical portion 24 facing the central axis direction of the first intermediate gear 20. In the absolute encoder 2, the main shaft-side sliding portion 25 of the first intermediate gear 20 contacts one end 9a of the leaf spring 9, which will be described later.

[0083] Leaf spring 9 is an example of an elastic member, for example, made of metal. Leaf spring 9 is a member used in the absolute encoder 2 to press the first intermediate gear 20 towards the central axis of the second intermediate gear shaft 23. Figures 4-6 as well as Figure 13As shown, the other end 9b of the leaf spring 9 is supported by the protrusion 132a of the support protrusion 132 of the base 3, and is fixed to the support protrusion 45 of the base 3 by the screw 8b and thus supported by the base 3. One end 9a of the leaf spring 9 is formed to contact the sliding part 25 on the main shaft side of the first intermediate gear 20, specifically, as Figure 4 and Figure 13 As shown, one end 9a of the leaf spring 9 is composed of two forked branches. A gap larger than the diameter of the first intermediate gear shaft 23 is formed between the two branches constituting one end 9a of the leaf spring 9. Thus, in the absolute encoder 2, the two branches of one end 9a of the leaf spring 9 contact the main shaft side sliding part 25 of the first intermediate gear 20 in such a way that the first intermediate gear shaft 23 passes through them.

[0084] like Figure 4 , Figure 6 , Figure 11 as well as Figure 13 As shown, in the absolute encoder 2, the leaf spring 9 is in a flexed state, with one end 9a in contact with the main shaft side sliding portion 25 of the first intermediate gear 20, and the other end 9b supported by the support protrusion 132 of the base 3 or fixed to the support protrusion 45 of the base 3. Therefore, when the leaf spring 9 generates elastic force, the main shaft side sliding portion 25 of the first intermediate gear 20 is pushed by one end 9a of the leaf spring 9. Due to this pushing force of the leaf spring 9, the first intermediate gear 20 is forced along the first intermediate gear shaft 23 in a direction from the support protrusion 131 on the main shaft gear 10 side towards the support protrusion 141 on the first auxiliary shaft gear 30 side. When the first intermediate gear 20 rotates in this state, the main shaft side sliding portion 25 of the first intermediate gear 20 rotates while in contact with one end 9a of the leaf spring 9.

[0085] like Figure 4 , Figure 6 as well as Figures 11-14 As shown, the secondary shaft-side sliding portion 26 of the first intermediate gear 20 is provided at the other end of the first intermediate gear 20, that is, the end end of the first secondary shaft gear 30 side of the first intermediate gear 20. Specifically, the secondary shaft-side sliding portion 26 is the end face of the other end of the cylindrical portion 24, and is an annular surface formed at the other end of the cylindrical portion 24 facing the central axis direction of the first intermediate gear 20, and is opposite to the main shaft-side sliding portion 25 in the central axis direction of the first intermediate gear 20.

[0086] In the absolute encoder 2, the sliding portion 26 on the secondary shaft side of the first intermediate gear 20 contacts the support protrusion 141, which defines the position of the first intermediate gear 20 in the direction of the central axis of the first intermediate gear shaft 23. As described above, the first intermediate gear 20 is pushed by the leaf spring 9 in the direction from the support protrusion 131 on the main shaft gear 10 side towards the support protrusion 141 on the secondary shaft gear 30 side. Therefore, the sliding portion 26 on the secondary shaft side of the first intermediate gear 20 is also pushed in the same direction and contacts the support protrusion 141. Thus, the pushing force of the leaf spring 9 is transmitted from the first secondary shaft gear 30 to the support protrusion 141, and the first intermediate gear 20 is stably supported in the direction from the support protrusion 131 towards the support protrusion 141. When the first intermediate gear 20 rotates, the sliding portion 26 on the secondary shaft side of the first intermediate gear 20 rotates while in contact with the support protrusion 141.

[0087] The aforementioned support protrusions 131 and 141 are examples of a first shaft support and a second shaft support that hold the first intermediate gear 20 in a rotatable position via the first intermediate gear shaft 23. Figure 5 , Figure 6 as well as Figures 11-13 As shown, support protrusions 131 and 141 are paired, for example, generally cuboid portions or portions having generally cuboid portions that protrude upwards from the base 101 of the base 3. Support protrusion 131 is located near the main shaft gear 10, as shown in top view (refer to...). Figure 6 , Figure 11 It is located on the left side of the base 3 and near the center in the front-rear direction. In addition, the support protrusion 141 is located near the first countershaft gear 30, and is located on the right side and front side of the base 3 when viewed from above.

[0088] like Figure 6 and Figures 11-13 As shown, support protrusions 131 and 141 function as support members that support the first intermediate gear shaft 23 so that it can swing along the horizontal plane; that is, they function as support members that support the first intermediate gear 20 so that it can swing along the horizontal plane. The first intermediate gear shaft 23 is a cylindrical rod-shaped member having a main shaft-side end 23a as one end and a secondary shaft-side end 23b as the other end. The main shaft-side end 23a is the end of the first intermediate gear shaft 23 located on the side of the main shaft gear 10 in the absolute encoder 2, and the secondary shaft-side end 23b is the end of the first intermediate gear shaft 23 located on the side of the first secondary shaft gear 30 in the absolute encoder 2.

[0089] The first worm gear portion 21, located on the main shaft side end 23a of the first intermediate gear shaft 23, can be driven by the force application mechanism 40 (described later) along the first meshing direction. Figure 12The first worm gear 21 can move in the direction of arrow P1, and cannot move along the direction of the intermediate gear shaft 23 (the direction of the central axis of the intermediate gear shaft 23) or in the direction orthogonal to the first meshing direction P1 (vertical direction) via the force application mechanism 40 described later. It should be noted that the first meshing direction refers to the direction in which the first worm gear 21 faces the first worm shaft 11 for meshing with the first worm shaft 11, as described above.

[0090] like Figures 11-14 As shown, a through hole 143 is formed in the support protrusion 131 for insertion into the spindle-side end 23a of the first intermediate gear shaft 23. The cross-sectional shape of the through hole 143 orthogonal to the extending direction is a circular hole shape. A circular hole shape refers to a shape with a perfect circle or approximately a perfect circle outline.

[0091] Furthermore, the absolute encoder 2 may also have a retaining ring (not shown) as a fixing part formed to engage with the main shaft side end 23a of the first intermediate gear shaft 23. The retaining ring is a member in which a portion that cannot pass through the through hole 143 of the support protrusion 131 is formed in the main shaft side end 23a of the intermediate gear shaft 23, and it is a member that partially increases the outer diameter of the main shaft side end 23a of the first intermediate gear shaft 23. The retaining ring is, for example, an annular member such as an E-ring that engages with a groove (not shown) formed in the first intermediate gear shaft 23. Furthermore, in the absolute encoder 2, the retaining ring is provided at the main shaft side end 23a of the first intermediate gear shaft 23 such that the retaining ring is located on the opposite side of the secondary shaft side end 23b relative to the support protrusion 131. That is, the retaining ring is positioned to contact the outer surface 131a of the support protrusion 131. The outer surface 131a is the surface of the support protrusion 131 facing the side opposite to the support protrusion 141. Thus, by contacting the retaining ring with the outer surface 131a of the support protrusion 131, the movement of the first intermediate gear shaft 23 in the direction from the main shaft end 23a toward the secondary shaft end 23b is restricted.

[0092] The second worm gear portion 22, located on the secondary shaft end 23b of the first intermediate gear shaft 23, can be driven along the second meshing direction by the force application mechanism 40 described later. Figure 12 The intermediate gear shaft 23 cannot move along the direction of the intermediate gear shaft 23 (the direction of the central axis of the intermediate gear shaft 23) or in the direction orthogonal to the second meshing direction P2 (the Z-axis direction) via the force application mechanism 40 described later. It should be noted that the second meshing direction refers to the direction in which the second worm portion 22 faces the second worm wheel portion 31 in order for the second worm portion 22 to mesh with the second worm wheel portion 31, as described above.

[0093] A through hole 145 is formed in the support protrusion 141 for insertion into the secondary shaft end 23b of the first intermediate gear shaft 23. The through hole 145 has an elongated shape in cross-section orthogonal to its extension direction. This elongated shape of the through hole 145 has a long axis and a short axis orthogonal to the long axis. The width of the long axis side is greater than the width of the short axis side. The width of the long axis side of the through hole 145 of the support protrusion 141 on the first secondary gear 30 side is greater than the diameter of the outer peripheral surface of the first intermediate gear shaft 23. Furthermore, the width of the short axis side of the through hole 145 is the same as or approximately the same as the diameter of the outer peripheral surface of the first intermediate gear shaft 23. In the absolute encoder 2, the direction of the long axis of the through hole 145 of the support protrusion 141 is parallel or approximately parallel to the horizontal plane. For the first intermediate gear shaft 23, whose secondary shaft side end 23b is inserted into the through hole 145 of the support protrusion 141, as described later, the force spring 41 engages with it and applies force to the secondary shaft side end 23b of the first intermediate gear shaft 23 in the second meshing direction P2.

[0094] Thus, for the intermediate gear shaft 23, the force-applying mechanism 40, support protrusion 131, and support protrusion 141 (described later) enable the secondary shaft end 23b to move parallel or substantially parallel to the horizontal direction with the main shaft end 23a as the fulcrum (= center of oscillation). Moreover, compared to the first worm gear portion 21 on the main shaft end 23a side, the second worm portion 22 on the secondary shaft end 23b side can move with a larger width parallel or substantially parallel to the horizontal direction. As a result, the first intermediate gear shaft 23, i.e., the first intermediate gear 20, supported by the support protrusions 131 and 141 under the force applied by the force-applying mechanism 40, can oscillate along the horizontal plane (XY plane).

[0095] In this configuration, the amount of movement (oscillation) of the first intermediate gear shaft 23 is determined by the depth of the through hole 143 formed in the support protrusion 131, i.e., the thickness of the support protrusion 131 in the central axis direction of the first intermediate gear shaft 23, the clearance between the through hole 143 and the first intermediate gear shaft 23, and the width of the long axis side of the through hole 145. However, when the clearance between the through hole 143 and the first intermediate gear shaft 23 is large, the first intermediate gear shaft 23 wobbles greatly and its position shifts. Therefore, it is desirable to avoid increasing this clearance. Thus, the thickness of the support protrusion 131 can be reduced by forming the support protrusion 131 with a thin plate or the like. In other words, the clearance between the through hole 143 and the first intermediate gear shaft 23 can be reduced by making the through hole 143 shallower, and the amount of movement of the first intermediate gear shaft 23 can be ensured. It should be noted that the amount of movement of the first intermediate gear shaft 23, which is pre-designed to be realized by the thickness of the support protrusion 131, is greater than the amount of movement of the first intermediate gear shaft 23 realized by the width of the long axis side of the through hole 145. Thus, the amount of movement of the first intermediate gear shaft 23 can be defined by the width of the long axis side of the through hole 145.

[0096] (First secondary shaft gear) Figure 15 It is a general representation. Figure 2 The absolute encoder 2 shown is a partial cross-sectional view cut along a plane that passes through the central axis of the first secondary shaft gear 30 and is orthogonal to the central axis of the first intermediate gear 20. Figure 16 It is a general representation. Figure 15 The absolute encoder 2 shown is an exploded perspective view showing the magnet Mq, magnet holder 35, first counterspindle gear 30, and bearing 135 disassembled.

[0097] like Figure 15 , Figure 16 As shown, the first counterspindle gear 30 is a cylindrical component into which the shaft portion 35b of the magnet holder 35 is pressed and fixed to the magnet holder 35. The first counterspindle gear 30 includes a second worm gear portion 31, a gear portion 32, and a through hole 33. The first counterspindle gear 30 is a component integrally molded from metal or resin; here, as an example, it is formed from polyacetal resin.

[0098] The second worm gear portion 31 is a gear that meshes with the second worm portion 22 of the first intermediate gear 20. The second worm gear portion 31 is an example of a second driven gear. The second worm gear portion 31 is, for example, composed of multiple teeth on the outer periphery of a cylindrical portion located on the upper side of the first counterspindle gear 30. As the first intermediate gear 20 rotates, the rotational force of the first intermediate gear 20 is transmitted to the first counterspindle gear 30 via the second worm portion 22 and the second worm gear portion 31 of the first intermediate gear 20.

[0099] Gear section 32 is a gear that meshes with gear section 71 of the second intermediate gear 70. Gear section 32 is an example of a third drive gear. Gear section 32 is, for example, composed of multiple teeth on the outer periphery of a cylindrical portion located below the first counterspindle gear 30. Furthermore, as... Figure 15 As shown, the gear portion 32 is formed on the lower side of the second worm gear portion 31, and its tooth tip circle diameter is smaller than that of the second worm gear portion 31. As the first countershaft gear 30 rotates, the rotational force of the first countershaft gear 30 is transmitted to the second intermediate gear 70 via the gear portion 32 of the first countershaft gear 30 and the gear portion 71 of the second intermediate gear 70.

[0100] like Figure 15 and Figure 16 As shown, the through hole 33 is a hole that passes through the first secondary shaft gear 30 along the central axis of the cylindrical first secondary shaft gear 30. The shaft portion 35b of the magnet holder 35 is pressed into the through hole 33, and the first secondary shaft gear 30 rotates integrally with the magnet holder 35.

[0101] The magnet retainer 35 has a magnet retaining portion 35a and a shaft portion 35b. The magnet retainer 35 is a component integrally molded from metal or resin; here, as an example, it is formed of non-magnetic stainless steel. Two outer rings of bearings 135 are pressed into the inner circumferential surface of the cylindrical bearing retainer portion 134 formed in the base 3. The shaft portion 35b of the magnet retainer 35 is a cylindrical component. The shaft portion 35b is pressed into the through hole 33 of the first counterspindle gear 30, and the lower part of the shaft portion 35b is inserted into and fixed to the inner rings of the two bearings 135. Therefore, the magnet retainer 35 is supported on the base 3 by the two bearings 135 and rotates integrally with the first counterspindle gear 30. The magnet retainer 35 is held in the bearing retainer portion 134 via the bearings 135 in a manner that allows it to rotate about a rotation axis parallel or substantially parallel to the Z-axis. It should be noted that a bearing stop 35c is pressed into the shaft portion 35b of the magnet retainer 35. When assembling the first set gear 30, firstly, the outer ring of the bearing 135, located on the upper surface 104 side of the base 3, is pressed into the bearing retaining portion 134. Then, the shaft portion 35b of the magnet retaining member 35 is inserted into the inner ring of the bearing 135. Next, the bearing stop 35c is pressed into the shaft portion 35b of the magnet retaining member 35 until it abuts against the lower side of the inner ring of the bearing 135. Then, the shaft portion 35b of the magnet retaining member 35 is inserted into the inner ring of the bearing 135, located on the lower surface 102 side of the base 3, and the outer ring is pressed into the bearing retaining portion 134 for fixation. Thus, the bearing stop 35c prevents the magnet retaining member 35 from falling out of the bearing 135 when inserted into it, and fixes the bearing 135 and the magnet retaining member 35 without gaps. Therefore, the vertical wobbling of the magnet Mg can be minimized as much as possible. For the two bearings 135, the pressing position is determined by abutting against the bearing positioning member 35d provided on the base 3. However, the bearing positioning member 35d may not be provided, and the surfaces of the upper surface 104 and the lower surface 102 of the base 3 and the surface of the bearing 135 may be positioned at the same height.

[0102] Furthermore, a magnet holding portion 35a is provided at the upper end of the magnet holding member 35. The magnet holding portion 35a is a bottomed cylindrical member. The magnet holding portion 35a has a recess that is recessed downward from the upper end surface of the magnet holding member 35. The inner peripheral surface of the recess of the magnet holding portion 35a is formed to contact the outer peripheral surface Mqd of the magnet Mq. Thus, in the absolute encoder 2, the magnet Mq is fixed to the magnet holding portion 35a by being accommodated in the recess of the magnet holding portion 35a.

[0103] The shaft portion 35b of the magnet holder 35 is supported by two bearings 135 disposed on the bearing holder portion 134 formed in the base 3, thereby preventing the magnet holder 35 from tilting. Furthermore, when the two bearings 135 are arranged such that the distance between them in the vertical direction of the shaft portion 35b is maximized, the effect of preventing the magnet holder 35 from tilting is further enhanced.

[0104] like Figure 16 As shown, the magnet Mq is a disk-shaped or substantially disk-shaped permanent magnet pressed into the magnet holding portion 35a of the magnet holder 35, having an upper surface Mqa and a lower surface Mqb. In the absolute encoder 2, the upper surface Mqa of the magnet Mq faces the lower surface of the angle sensor Sp at a certain distance. The central axis MqC of the magnet Mq (representing the axis of the center of the magnet Mq or the axis passing through the center of the boundary of the magnetic poles) is aligned with the central axis SC of the magnet holder 35, the central axis GC2 of the first secondary shaft gear 30, and the central axis BC of the bearing 135. By aligning the central axes in this way, the rotation angle or rotation amount can be detected with higher accuracy.

[0105] It should be noted that, in the embodiments of the present invention, ideally, the two magnetic poles (N / S) of the magnet Mq are formed adjacent to each other in a horizontal plane (XY plane) perpendicular to the central axis MqC of the magnet Mq. This further improves the detection accuracy of the rotation angle or rotation amount of the angle sensor Sq. It should also be noted that the magnet Mq is formed, for example, from a ferrite system, an Nd(neodymium)-Fe(iron)-B(boron) system, or other magnetic materials. The magnet Mq can also be, for example, a rubber magnet containing a resin binder, a bonded magnet, or the like.

[0106] (Second intermediate gear) Figure 17 It is a general representation. Figure 2 The diagram shows a partial cross-sectional view of the absolute encoder 2, cut along the plane passing through the central axis of the second intermediate gear 70 and the second counterspindle gear 63. Figure 18 It is Figure 17 The enlarged cross-sectional view of the second intermediate gear 70 shown is shown in the figure.

[0107] like Figure 17 , 18As shown, the second intermediate gear 70 is a rotatable component supported by a shaft 75 fixed to the shaft support portion 136 of the base 3, and includes a gear portion 71, a gear portion 72, and a main body portion 73. The second intermediate gear 70 is, for example, a component integrally molded from a resin material with low sliding resistance. An example of the resin material for the second intermediate gear 70 is polyacetal resin. The shaft 75 is fixed to the shaft support portion 136 of the base 3 in such a way that the central shaft GC3 of the second intermediate gear 70 is parallel or substantially parallel to the central shaft GC2 of the first secondary shaft gear 30. For example, the lower end (lower end face 75a) of the shaft 75 is pressed into the through hole 136a of the shaft support portion 136 of the base 3 for fixation.

[0108] The main body 73 is a cylindrical or substantially cylindrical portion with a through hole 74 inside. The through hole 74 is formed so that a shaft 75 can be slidably inserted relative to the shaft 75. The gear portion 71 is a gear that meshes with the gear portion 32 of the first countershaft gear 30. The gear portion 71 is an example of a third driven gear. The gear portion 71 is, for example, composed of a plurality of teeth provided on the outer periphery of the lower side of the main body 73. When the first countershaft gear 30 rotates, the rotational force of the first countershaft gear 30 is transmitted to the gear portion 71 of the second intermediate gear 70 via the gear portion 32 of the first countershaft gear 30. As a result, the second intermediate gear 70 rotates.

[0109] Gear section 72 is a gear that meshes with gear section 64 of the second counterspindle gear 63. Gear section 72 is an example of a fourth drive gear. Gear section 72 is composed of, for example, multiple teeth provided on the outer periphery of the upper side of the main body section 73, and is provided on the upper side of gear section 71. When the second intermediate gear 70 rotates, the rotational force of the second intermediate gear 70 is transmitted to gear section 64 of the second counterspindle gear 63 via gear section 72. As a result, the second counterspindle gear 63 rotates.

[0110] like Figure 17 , 18 As shown, in the second intermediate gear 70, the through hole 74 is a hole that extends through the main body 73 in such a way that the central axis of the through hole 74 coincides or substantially coincides with the central axis of each of the gear parts 71 and 72. Furthermore, the through hole 74 is formed such that the central axis GC3 of the second intermediate gear 70 coincides or substantially coincides with the central axis of the shaft 75.

[0111] The lower end face (lower end face 73a) of the main body 73 contacts the upper surface 104 of the base 3, and is configured to slide relative to the upper surface 104. The lower end face 73a of the main body 73 is, for example, a plane or a generally flat plane that is orthogonal or substantially orthogonal to the central axis GC3 of the second intermediate gear 70. Furthermore, the upper end face (upper end face 73b) of the main body 73 contacts the member facing which the upper end face 73b is located, and is configured to slide relative to that member. The upper end face 73b of the main body 73 is, for example, a plane or a generally flat plane that is orthogonal or substantially orthogonal to the central axis GC3 of the second intermediate gear 70.

[0112] An annular groove 75c is formed around the axis of the shaft 75 on the upper end (upper end face 75b) side. A retaining ring 76 is engagedly formed in the groove 75c. The retaining ring 76 is a component used to maintain the second intermediate gear 70 in a rotatable state supported by the shaft 75, and is a component that partially increases the outer diameter of the portion of the shaft 75 on the upper end face 75b side. Figure 18 As shown, the retaining ring 76 is, for example, a C-shaped ring, an E-shaped ring, or other annular component. In the absolute encoder 2, the slot 75c is provided on the shaft 75 such that the retaining ring 76 faces the upper end face 73b of the main body 73 of the second intermediate gear 70. In the absolute encoder 2, the retaining ring 76 fitted in the slot 75c can also be in contact with the upper end face 73b of the second intermediate gear 70, or the retaining ring 76 can be positioned with a gap between it and the upper end face 73b of the second intermediate gear 70. The retaining ring 76 restricts the movement of the shaft 75 of the second intermediate gear 70 in the axial direction.

[0113] The second intermediate gear 70 is configured as described above. In the absolute encoder 2, the shaft 75 is inserted into the through hole 74 of the second intermediate gear 70, and the retaining ring 76 is fitted into the groove 75c of the shaft 75, thereby assembling the second intermediate gear 70 in the absolute encoder 2. In the absolute encoder 2, the second intermediate gear 70 can rotate about the shaft 75 as the rotation axis, about a rotation axis that is parallel or substantially parallel to the central axis GC2 of the first secondary shaft gear 30. Furthermore, the second intermediate gear 70 can slide against the upper surface 104 of the base 3 and the retaining ring 76 fitted to the shaft 75, and the movement of the shaft 75 in the axial direction is restricted.

[0114] (Second auxiliary shaft gear) Figure 19 It is to have Figure 17 An enlarged cross-sectional view of the magnet holder 61 of the second auxiliary shaft gear 63 shown. Figure 20 It is a general representation of... Figure 19 The image shows an exploded perspective view of the magnet holder 61 in a disassembled state.

[0115] like Figure 17 , 19As shown in Figure 20, the magnet holder 61 is a rotatable member supported by a second counterspindle gear shaft 62 fixed to the shaft support portion 137 of the base 3, and includes a second counterspindle gear 63, a magnet holder portion 65, and a magnet Mr. The magnet holder portion 65 is a member for clamping the magnet Mr between itself and the second counterspindle gear 63, thereby fixing the magnet Mr in the magnet holder 61. The second counterspindle gear shaft 62 is fixed to the shaft support portion 137 of the base 3 in such a way that its axis (central axis GC4) is parallel or substantially parallel to the central axis GC3 of the second intermediate gear 70. For example, the lower end (lower end face 62a) of the second counterspindle gear shaft 62 is pressed into the through hole 137a of the shaft support portion 137 of the base 3 for fixation. Furthermore, in the absolute encoder 2, the second counterspindle gear shaft 62 is fixed to the base 3 such that the magnet Mr of the magnet holder 61 and the angle sensor Sr mounted on the substrate 5 are opposite each other in the direction of the central axis GC3.

[0116] The second counterspindle gear 63 includes a gear portion 64, a main body portion 66, and a magnet support portion 67. The second counterspindle gear 63 is, for example, a component integrally molded from a resin material with low sliding resistance. That is, the gear portion 64, the main body portion 66, and the magnet support portion 67 are integrally formed from the same material and each becomes part of the second counterspindle gear 63. An example of the resin material for the second counterspindle gear 63 is polyacetal resin. The main body portion 66 is a cylindrical or substantially cylindrical portion with a through hole 66a inside. The through hole 66a is formed so that the second counterspindle gear shaft 62 can be slidably inserted relative to the second counterspindle gear shaft 62. The gear portion 64 is a gear that meshes with the gear portion 72 of the second intermediate gear 70. The gear portion 64 is an example of a fourth driven gear. The gear portion 64 is, for example, composed of a plurality of teeth provided on the outer periphery of the main body portion 66. In the illustrated example, the gear portion 64 is formed as a disc-shaped portion protruding outward from the outer periphery of the main body portion 66, and is configured to have a plurality of teeth on the outer periphery of this disc-shaped portion. As the second intermediate gear 70 rotates, the rotational force of the second intermediate gear 70 is transmitted to the gear portion 64 of the second countershaft gear 63 via the gear portion 72 of the second intermediate gear 70. Consequently, the second countershaft gear 63 rotates.

[0117] like Figure 17 , 19 As shown, in the second counterspindle gear 63, the through hole 66a extends through the main body 66 in such a way that the central axis of the through hole 66a is aligned with or substantially aligned with the central axis of the gear portion 64. Furthermore, the through hole 66a is formed such that the central axis GC4 of the second counterspindle gear 63 is aligned with or substantially aligned with the central axis of the second counterspindle gear shaft 62.

[0118] The lower end face (lower end face 66b) of the main body 66 contacts the upper surface 104 of the base 3, and is configured to slide relative to the upper surface 104. The lower end face 66b of the main body 66 is, for example, a plane or a plane that is orthogonal or substantially orthogonal to the central axis GC4 of the second counterspindle gear 63. Furthermore, the upper end face (upper end face 66c) of the main body 66 contacts the member facing which the upper end face 66c is located, and is configured to slide relative to that member. The upper end face 66c of the main body 66 is, for example, a plane or a plane that is orthogonal or substantially orthogonal to the central axis GC4 of the second counterspindle gear 63.

[0119] The magnet support portion 67 is a cylindrical portion extending upward from the upper part of the gear portion 64 within the main body portion 66, extending along the central axis GC4 of the second counterspindle gear 63. The magnet support portion 67 extends upward beyond the upper end surface 66c of the main body portion 66, forming a cylindrical space within the magnet support portion 67 by the upper end surface 66c of the main body portion 66 and the inner peripheral surface (inner peripheral surface 67a) of the magnet support portion 67. The outer peripheral surface 67b of the magnet support portion 67 is located on the inner peripheral side of the top end of the gear portion 64. The magnet support portion 67 is, for example, a cylindrical or substantially cylindrical member centered or approximately centered on the central axis GC4 of the second counterspindle gear 63. Figure 19 As shown, the upper end face 66c of the main body 66 is connected to the inner peripheral surface 67a of the magnet support portion 67. For the main body 66, the portion connecting to the magnet support portion 67 may be larger than the portion lower than the gear portion 64 on the outer peripheral side; alternatively, the portion connecting to the magnet support portion 67 may be no larger than the portion lower than the gear portion 64 on the outer peripheral side. It should be noted that the shape of the magnet support portion 67 is not limited to a cylindrical or approximately cylindrical shape; it can also be other shapes. For example, the shape of the magnet support portion 67 may also be a square tube or similar shape.

[0120] The upper end face (upper end face 67c) of the magnet support 67 is a plane or approximately plane that is orthogonal or substantially orthogonal to the central axis GC4 of the second counterspindle gear 63. In the absolute encoder 2, the inner circumferential surface 67a of the magnet support 67 is located on the inner circumferential side of the magnet Mr facing the outer circumferential side (outer circumferential surface Mrd) so that the magnet Mr can make full circumferential contact with the upper end face 67c. Furthermore, in the absolute encoder 2, the magnet support 67 is formed such that the upper end face 67c is located on the upper end face (upper end face 62b) of the second counterspindle gear shaft 62. It should be noted that the upper end face 67c of the magnet support 67 is parallel or substantially parallel to the upper surface 104 of the base 3, and rotates without surface jitter relative to the upper surface 104 of the base 3 when the second counterspindle gear 63 rotates.

[0121] The magnet holding part 65 is a component formed of a bottomed cylindrical resin material. The resin material of the magnet holding part 65 is, for example, a resin material with an adhesive. Specifically, the magnet holding part 65 has a cylindrical extending part 68 and a bottom 69 extending from one end of the cylindrical part 68 toward the inner circumference. The cylindrical part 68 houses the magnet support part 67 of the second countershaft gear 63, forming an insert part 65a that can fit the magnet holding part 65 into the magnet support part 67, and the cylindrical part 68 and the bottom 69 form a magnet receiving part 65b that can house and hold the magnet Mr.

[0122] The cylindrical portion 68 of the magnet retainer portion 65 has a cylindrical or substantially cylindrical inner circumferential surface 68a extending along a central axis that coincides with or is substantially coincident with the central axis MC4 of the second counterspindle gear 63 in the absolute encoder 2. The inner circumferential surface 68a is a surface facing the inner circumferential side, extending from the end opposite to the end of the cylindrical portion 68 on the bottom 69 side (open end 68c) towards the bottom 69 side, forming an opening at the open end 68c of the cylindrical portion 68. The space formed inside the inner circumferential surface 68a is an insert portion 65a. The inner circumferential surface 68a is formed such that when the magnet support portion 67 of the second counterspindle gear 63 is received in the insert portion 65a, it contacts the outer circumferential surface 67b of the magnet support portion 67 in an interference fit with the magnet retainer portion 65. It should be noted that the shape of the inner circumferential surface 68a of the cylindrical portion 68 is not limited to a cylindrical or substantially cylindrical shape, but can also be other shapes. The shape of the inner circumferential surface 68a of the cylindrical portion 68 corresponds to the shape of the magnet support portion 67 that it houses.

[0123] Furthermore, the cylindrical portion 68 of the magnet retainer portion 65 has a cylindrical or substantially cylindrical inner circumferential surface 68b extending along a central axis that coincides with or substantially coincides with the central axis MC4 of the second auxiliary shaft gear 63 in the absolute encoder 2, and also extends along a central axis that coincides with or substantially coincides with the central axis MrC of the magnet Mr. The inner circumferential surface 68b is a surface facing the inner circumferential side, extending between the inner circumferential surface 68a and the bottom surface 69a of the bottom 69. The space formed internally by the inner circumferential surface 68b and the bottom surface 69a of the bottom 69 is the magnet receiving portion 65b. The inner circumferential surface 68b is formed such that when the magnet Mr is received in the magnet receiving portion 65b, it is radially opposed to the outer circumferential surface Mrd of the magnet Mr. The inner circumferential surface 68b is located on the inner circumferential side of the inner circumferential surface 68a, and a step is formed between the inner circumferential surfaces 68a and 68b. Furthermore, the width of the inner circumferential surface 68b along its central axis is smaller than the width along the central axis MrC of the magnet Mr. The inner circumferential surface 68b can be formed such that when the magnet Mr is housed in the magnet housing portion 65b, it is radially opposed to the outer circumferential surface Mrd of the magnet Mr, or it can be formed such that the outer circumferential surface Mrd of the magnet Mr is not radially opposed to it.

[0124] The bottom 69 of the magnet holding part 65 is a disc-shaped portion extending toward the inner circumference from the end (closed end 68d) opposite to the open end 68c of the cylindrical part 68, and has the aforementioned bottom surface 69a. The bottom surface 69a is the surface facing the magnet receiving part 65b, and is a plane or approximately plane that is orthogonal or substantially orthogonal to the central axis of the cylindrical part 68. Furthermore, an opening 69b is formed in the bottom 69 as a through hole extending through the bottom 69 in the central axis of the cylindrical part 68. The bottom surface 69a of the bottom 69 is formed to contact the upper surface Mra of the magnet Mr when the magnet Mr is received in the magnet receiving part 65b, with the central axis MrC of the magnet Mr parallel or substantially parallel to the central axis of the cylindrical part 68. Furthermore, the opening 69b of the bottom 69 is formed to allow the magnetic flux of the magnet Mr to pass through the opening 69b when the magnet Mr is received in the magnet receiving part 65b.

[0125] As described above, the second counterspindle gear shaft 62 is formed of a magnetic material, and an attractive force generated by magnetic force is generated between the magnet Mr and the second counterspindle gear shaft 62 in the direction of the rotation axis of the magnet holder 61. Specifically, the second counterspindle gear shaft 62 generates a magnetic force that exerts a force on the magnet Mr in the direction of the second counterspindle gear shaft 62.

[0126] Furthermore, on the upper end (upper end face 62b) side of the second counterspindle gear shaft 62, an annular groove 62c is formed around the axis of the second counterspindle gear shaft 62, and a retaining ring 62d is engagedly formed in the groove 62c. The retaining ring 62d is a component used to limit the axial movement of the second counterspindle gear shaft 62 of the magnet holder 61, and is a component that partially increases the outer diameter of the portion of the second counterspindle gear shaft 62 on the upper end face 62b side. Figure 19 As shown, the retaining ring 62d is, for example, a C-shaped ring, an E-shaped ring, or other annular component. In the absolute encoder 2, the slot 62c is provided on the second counterspindle gear shaft 62 such that the retaining ring 62d is positioned opposite the upper end face 66c of the main body 66 of the second counterspindle gear 63, leaving space between them.

[0127] like Figure 19 , 20 As shown, the magnet Mr is a disk-shaped or substantially disk-shaped permanent magnet housed within the magnet receiving portion 65b of the magnet holding portion 65, having an upper surface Mra, a lower surface Mrb, and an outer peripheral surface Mrd. It should be noted that, in embodiments of the present invention, ideally, the two magnetic poles (N / S) of the magnet Mr are formed adjacent to each other in a horizontal plane (XY plane) perpendicular to the central axis MrC of the magnet Mr. This further improves the detection accuracy of the rotation angle or rotation amount of the angle sensor Sr. It should be noted that the magnet Mr is formed, for example, from a ferrite system, an Nd(neodymium)-Fe(iron)-B(boron) system, or other magnetic materials. The magnet Mr can also be, for example, a rubber magnet containing a resin binder, a bonded magnet, etc. Furthermore, Figure 21 This is a schematic perspective view of a cylindrical magnet Mr applicable to embodiments of the present invention. In the illustrated example magnet Mr, the first magnetic pole portion N and the second magnetic pole portion S are arranged and adjacent to each other in the radial direction D1, with the center or approximately the center of the radial direction D1 of the magnet Mr as the boundary. Furthermore, in the illustrated example magnet Mr, the first magnetic pole portion N and the second magnetic pole portion S are arranged and adjacent to each other in the axial direction D2, with the center or approximately the center of the axial direction (central axis MrC) as the boundary. It should be noted that... Figure 21 The arrow DM shown indicates the magnetization direction. Such a magnetization direction is generally called planar magnetization, and a magnet with planar magnetization is used on the magnet Mr.

[0128] The magnet holder 61 is configured as described above. In the absolute encoder 2, the second counterspindle gear shaft 62 is inserted into the through hole 66a of the main body 66 of the second counterspindle gear 63, and the retaining ring 62d is fitted into the groove 62c of the second counterspindle gear shaft 62, thereby assembling the second counterspindle gear 63 in the absolute encoder 2. In the absolute encoder 2, the magnet holder 61 can rotate about a rotation axis. The rotation axis of the magnet holder 61 is aligned with or substantially aligned with the central axis GC4 of the second counterspindle gear shaft 62. The retaining ring 62d and the portion on the upper end face 62b side of the second counterspindle gear shaft 62 are accommodated in the space formed on the inner circumferential side of the magnet support portion 67 of the second counterspindle gear 63.

[0129] Furthermore, in the absolute encoder 2, the magnet Mr is housed in the magnet receiving portion 65b of the magnet holding portion 65, and the magnet Mr is fixed to the magnet holding portion 65. The magnet Mr is fixed to the magnet holding portion 65 by bonding with an adhesive. For example, the inner peripheral surface 68b of the magnet receiving portion 65b forming the magnet holding portion 65 and the outer peripheral surface Mrd of the magnet Mr are bonded together by an adhesive material. The magnet Mr is fixed to the magnet holding portion 65 with its lower surface Mrb in contact with the bottom surface 69a of the magnet receiving portion 65b forming the magnet holding portion 65. This allows for alignment of the central axis MrC of the magnet Mr with the central axis of the second counterspindle gear shaft 62, and alignment of the central axis MrC of the magnet Mr with the rotation axis of the second counterspindle gear shaft 62. This enables higher precision sensing of the rotation amount or rotation angle of the magnet Mr by the angle sensor Sr. It should be noted that the fixing of the magnet Mr to the magnet receiving part 65b is not limited to being achieved by an adhesive, but can also be achieved by other fixing methods such as inserting the magnet Mr, such as the first secondary shaft gear 30, into the magnet receiving part 65b.

[0130] Furthermore, in the absolute encoder 2, as described above, the magnet retaining part 65, to which the magnet Mr is fixed, is fitted into the magnet support part 67 of the second counterspindle gear 63, and the magnet retaining part 65 is fixed to the second counterspindle gear 63, thereby assembling the magnet retaining part 61. Specifically, the magnet support part 67 is pressed into the fitting part 65a of the magnet retaining part 65, forming an inner peripheral surface 68a of the fitting part 65a of the magnet retaining part 65 that pushes the outer peripheral surface 67b of the magnet support part 67 inward, and the outer peripheral surface 67b of the magnet support part 67 pushes the inner peripheral surface 68a of the magnet retaining part 65 inward, thus fixing the magnet retaining part 65 to the second counterspindle gear 63. It should be noted that the fixing of the magnet retaining part 65 to the second counterspindle gear 63 is not limited to being achieved by fitting, but can also be achieved by other fixing methods.

[0131] In the magnet holder 61 assembled by fixing the magnet holder 65 to the second counterspindle gear 63, the magnet Mr is clamped and fixed between the second counterspindle gear 63 and the magnet holder 65. Specifically, the upper end face 67c of the magnet support 67 contacts the lower surface Mrb of the magnet Mr, and the magnet Mr is clamped between the upper end face 67c of the magnet support 67 and the bottom surface 69a of the bottom 69 of the magnet holder 65, and the magnet Mr is fixed in the direction of its central axis MrC. On the other hand, the radial fixation of the magnet Mr orthogonal to its central axis MrC is accomplished by bonding the outer peripheral surface Mrd of the magnet Mr to the inner peripheral surface 68b of the magnet holder 65.

[0132] Furthermore, in the absolute encoder 2, the upper surface Mra of the magnet Mr is opposed to the angle sensor Sr in the direction of the central axis MrC of the magnet Mr via an opening 69b formed in the bottom 69 of the magnet holding member 65. Thus, the angle sensor Sr can sense the magnetic flux from the magnet Mr.

[0133] As described above, the magnet retainer 61 assembled in the absolute encoder 2 can rotate about a rotation axis that is parallel or approximately parallel to the central axis GC3 of the second intermediate gear 70, with the second secondary gear shaft 62 as the rotation axis.

[0134] Furthermore, the second counterspindle gear shaft 62 is formed of a magnetic material, generating a magnetic force that exerts a force on the magnet Mr in the direction of the second counterspindle gear shaft 62. Therefore, in the absolute encoder 2, the magnetic force from the second counterspindle gear shaft 62 acts on the magnet Mr, attracting the magnet Mr toward the second counterspindle gear shaft 62. In the illustrated orientation (upright state), the lower end face 66b of the main body 66 of the second counterspindle gear 63 slidably contacts the upper surface 104 of the base 3. Through the axial force from the second counterspindle gear shaft 62, the magnet holding member 61 is forced in the direction of contact between the lower end face 66b of the second counterspindle gear 63 and the upper surface 104 of the base 3. Here, compared to a radially magnetized magnet, a surface-magnetized magnet has the characteristic that the magnetic flux density is concentrated in the center of the magnet. As described above, the magnet Mr is a surface-magnetized magnet, and the second counterspindle gear shaft 62 is formed of a magnetic material. Therefore, the magnetic flux density of magnet Mr is further concentrated near the center of magnet Mr by the magnetic body of the second counterspindle gear shaft 62, so that the angle sensor Sr can detect the magnetic flux with high precision in the absolute encoder 2.

[0135] On the other hand, when the absolute encoder 2 is reversed from its upright state (inverted state), the magnet holder 61 can move relative to the second counterspindle gear shaft 62 in the direction of the central axis MC4 of the second counterspindle gear 63 through the gap between the retaining ring 62d and the upper end face 66c of the main body 66 of the second counterspindle gear 63. That is, the magnet Mr moves towards the angle sensor Sr, and the interval between the magnet Mr and the angle sensor Sr may change. However, in the absolute encoder 2, the second counterspindle gear shaft 62 is formed of a magnetic material, and the second counterspindle gear shaft 62 attracts the magnet Mr towards the second counterspindle gear shaft 62 through its magnetic force. Therefore, even when the absolute encoder 2 is inverted, the magnet holder 61 maintains the state in which the lower end face 66b of the second counterspindle gear 63 is in contact with the upper surface 104 of the base 3, and the magnet holder 61 maintains its position in the direction of the central axis MC4 in the upright state, preventing the magnet Mr from moving towards the angle sensor Sr. Therefore, even in the inverted state, the distance between the magnet Mr and the angle sensor Sr remains the same as in the upright state.

[0136] Thus, in the absolute encoder 2, the interval between the magnet Mr and the angle sensor Sr will not change according to the usage posture of the absolute encoder 2, which can reduce the impact of the usage posture of the absolute encoder 2 on the detection accuracy.

[0137] Furthermore, the second counterspindle gear 63 restricts the movement of the second counterspindle gear shaft 62 in the axial direction by means of a retaining ring 62d fitted to the second counterspindle gear shaft 62. That is, the magnet retainer 61 restricts the movement of the second counterspindle gear shaft 62 in the axial direction. Therefore, even when a large impact is applied to the absolute encoder 2, and a force is applied that overcomes the magnetic force of the second counterspindle gear shaft 62, causing the magnet retainer 61 to move upwards in the axial direction of the second counterspindle gear shaft 62, the movement of the magnet retainer 61 is still restricted by the retaining ring 62d. Therefore, it is possible to prevent adverse situations such as the magnet retainer 61 detaching from the second counterspindle gear shaft 62.

[0138] As described above, the magnet support portion 67 in the second counterspindle gear 63 also functions as a magnet support portion that supports the magnet Mr on the upper side of the second counterspindle gear 63 via the upper end face 67c, which is the upper end face. The magnet retaining portion 65 functions as a magnet retaining portion that covers the magnet Mr and the second counterspindle gear 63 from above and retains the magnet Mr on the upper end face 67c of the magnet support portion 67.

[0139] Furthermore, the magnet retaining part 65 is formed of a resin material with a higher elongation at break than the second counterspindle gear 63. The magnet retaining part 65 has a bottom surface 69a that functions as a magnet engagement part and an inner peripheral surface 68a that functions as an insert part 65a.

[0140] The press-fit assembly structure is one of the simplest methods to ensure concentricity between assembled components without the need for special equipment. In a press-fit structure between resin components such as the magnet retainer 65 and the second counterspindle gear 63, it is necessary to consider the retention and centering of the assembled components, as well as the retention strength between the press-fit components, by using a portion of the component shape, specifically the outer peripheral surface 67b of the magnet support 67, as a guide. Therefore, for the resin material of the magnet retainer 65 and the second counterspindle gear 63, it is necessary to select a reinforcing material with added filler, which tends to have a low coefficient of linear expansion and a high modulus of elasticity. However, such a resin material with a low coefficient of linear expansion and a high modulus of elasticity is prone to cracking during press-fitting and it is difficult to obtain the durability to maintain the pressed-fit state.

[0141] The magnet retainer portion 65, having an insert portion 65a, has a release space for deformation after being pressed in outwards circumferentially, making it susceptible to tensile stress. On the other hand, the second counterspindle gear 63, pressed into the shaft side, lacks this release space for deformation after the magnet retainer portion 65 is pressed in; therefore, compared to the magnet retainer portion 65, it has a lower risk of stress-induced breakage. Thus, in the absolute encoder 2, considering the elongation at break characteristics of the material, the magnet retainer portion 65 can be designed with a higher elongation at break than the second counterspindle gear 63 without altering the reinforcing filler content, thereby preventing breakage during pressing. Here, the elongation at break characteristic (elongation at break) refers to the elongation at break of the test piece in a tensile test, or the elongation immediately before breakage between determined puncture points.

[0142] (Second auxiliary shaft gear shaft) The specific shape of the second auxiliary shaft gear shaft 62 described above will be explained below. Figure 22 This is an enlarged sectional view of one end 62f on the lower end face 62a side of the second auxiliary shaft gear shaft 62.

[0143] The second auxiliary shaft gear 62 of the second auxiliary shaft gear 63 is a shaft that is pressed into and fixed to the through hole 137a of the shaft support portion 137 of the base 3 as described above. Figure 22 As shown, the second auxiliary gear shaft 62 has a tapered surface 62e. The tapered surface 62e is an inclined outer peripheral surface with a diameter of one end 62f smaller than the diameter of the peripheral surface 62g. In the tapered surface 62e, the connection portion 62h between the tapered surface 62e of the second auxiliary gear shaft 62 and the outer peripheral surface 62g is connected by a curved surface. That is, in the tapered surface 62e, the connection portion 62h between the tapered surface 62e and the outer peripheral surface 62g is machined with a curved surface.

[0144] Figure 23 , 24 This is a schematic diagram showing the second auxiliary shaft gear shaft 62 being pressed into the through hole 137a of the base 101 of the base 3.

[0145] like Figure 23 , 24As shown, when the second auxiliary shaft gear 62 is pressed into the through hole 137a of the base 3, after the tapered surface 62e is inserted into the through hole 137a, the connecting portion 62h between the tapered surface 62e and the peripheral surface 62g contacts the through hole 137a. Similar to the connecting portions 126a and 127a of the tapered surfaces 126 and 127 of the main shaft connector 12, the connecting portion 62h is also surface-machined. Therefore, the second auxiliary shaft gear 62 is smoothly pressed into the through hole 137a, thus preventing grinding of both the second auxiliary shaft gear 62 and the through hole 137a. Furthermore, it is preferable that the surface roughness Rmax (maximum roughness) of the main shaft connector 12 is set to 1.6 [μm] or less. Therefore, the second auxiliary shaft gear 62, like the main shaft connector 12, can suppress the scattering of debris, etc. Furthermore, the second auxiliary shaft gear 62 can prevent it from tilting (inclining) and being pressed in due to component grinding. Moreover, the second auxiliary shaft gear 62 can reduce the pressing amount (the required pressing dimension) by suppressing tilting of the second auxiliary shaft gear 62.

[0146] It should be noted that, in the absolute encoder 2, the example of performing surface machining on the connection between the tapered face and the peripheral face of the shaft pressed into the support member is not limited to the main shaft joint 12 and the second auxiliary shaft gear shaft 62 described above. In the absolute encoder 2, for example, surface machining may also be performed on the connection between the tapered face and the peripheral face of the support shaft of the first auxiliary shaft gear 30.

[0147] In the absolute encoder 2, the main shaft gear 10, the first intermediate gear 20, the first counter-shaft gear 30, the second intermediate gear 70, and the second counter-shaft gear 63 are arranged as described above. The rotation axes of the main shaft gear 10 and the first counter-shaft gear 30 are parallel to each other, and the rotation axis of the first intermediate gear 20 is in a torsional position relative to the rotation axes of each of the main shaft gear 10 and the first counter-shaft gear 30. Furthermore, the rotation axes of the first counter-shaft gear 30, the second intermediate gear 70, and the second counter-shaft gear 63 are parallel to each other. By configuring these gears, the amount of rotation of the main shaft gear 10 after multiple rotations can be determined based on the detection results of angle sensors Sq and Sr. Because the rotation axis of the first intermediate gear 20 is in a torsional position relative to the rotation axes of the main shaft gear 10 and the first counter-shaft gear 30 and is orthogonal to them in the main view, the absolute encoder 2 can be made thinner by forming a curved transmission path.

[0148] (Backlash reduction mechanism) As described above, the absolute encoder 2 has a force-applying mechanism 40 that applies force to the second worm portion 22 in the direction of the second worm gear portion 31. The force-applying mechanism 40 is a backlash-reducing mechanism that reduces the backlash between the second worm portion 22 and the second worm gear portion 31. Figure 5 , Figure 6 , Figure 11 , Figure 14 As shown, the force-applying mechanism 40 includes a force-applying spring 41, a support protrusion 45, and a screw 8b for fixing the force-applying spring 41 to the support protrusion 45. Furthermore, the through hole 143 and the through hole 145 of the support protrusion 131 of the base 3 also constitute the force-applying mechanism 40.

[0149] The force-applying spring 41 is a component used to generate a pushing force that pushes the second worm gear portion 22 towards the second worm wheel portion 31; it is an elastic component. The force-applying spring 41 is, for example, a leaf spring, formed of a metal plate. Figure 12 , Figure 14 As shown, specifically, the force-applying spring 41 has: a spring portion 42, which is a portion that generates pushing force through elastic deformation; and an engaging portion 43 and a fixing portion 44, which are portions that face each other across the spring portion 42. The engaging portion 43 and the fixing portion 44 are portions that form a pair of ends in the force-applying spring 41.

[0150] The fixing part 44 is formed to be fixed by a screw 8b to a support protrusion 45 protruding from the upper surface 104 of the base 101 of the base 3. The screw 8b is an example of a fixing member, and a hole 44a for inserting the screw 8b is formed in the fixing part 44. The fixing part 44 extends in a planar shape and is fixed to the support protrusion 45 by the screw 8b in a state of contact with the planar support surface 45a of the support protrusion 45.

[0151] The engaging portion 43 has a shape that allows it to engage with the secondary shaft side end 23b of the first intermediate gear shaft 23. For example... Figure 13 , Figure 14 As shown, the engaging portion 43 has, for example, an engaging groove 43a, which forms a gap extending along the extending direction of the engaging portion 43 from the spring portion 42. The engaging groove 43a is a groove that opens towards the top edge 43b, forming a bifurcated branch like one end 9a of the leaf spring 9 described above. The top edge 43b is the end edge of the engaging portion 43 that faces away from the connecting portion 43c of the spring portion 42. The engaging portion 43 also extends in a planar shape. An engaging groove 23d is formed at the secondary shaft side end 23b of the first intermediate gear shaft 23. The engaging groove 43a of the engaging portion 43 can engage with the engaging groove 23d, which is an annular groove extending in a direction or substantially orthogonal to the central axis of the first intermediate gear shaft 23. One side of the engaging groove 43a, parallel to the vertical direction, pushes the first intermediate gear shaft 23 in the engaging groove 23d, thereby applying force to the first intermediate gear 20 in the direction of the second worm portion 22 toward the second worm wheel portion 31. Furthermore, the two sides of the engaging groove 43a, parallel to the horizontal direction, contact the first intermediate gear shaft 23 in the engaging groove 23d, thereby restricting the vertical movement of the force-applying spring 41 by the first intermediate gear shaft 23.

[0152] The spring portion 42 has a shape that easily deforms elastically toward the engaging portion 43 in the engaging direction toward the first intermediate gear shaft 23. Specifically, for example... Figure 14 As shown, it has a shape that easily bends in the extending direction of the engagement groove 43a. For example, the spring portion 42 is bent to protrude in the opposite direction to the direction in which force is applied to the first intermediate gear 20.

[0153] With the spring portion 42 raised from the fixed portion 44 on the side opposite to the support protrusion 45, the force-applying spring 41 is fixed to the support protrusion 45 by screw 8b at the fixed portion 44. In this fixed state, the engaging groove 43a of the engaging portion 43 engages with the engaging groove 23d of the first intermediate gear shaft 23. Furthermore, in the engaged state, the spring portion 42 generates a pushing force that pushes the engaging portion 43 against the first intermediate gear shaft 23. The dimensions of the spring portion 42, the dimensions of the engaging portion 43, and the angle of the extending direction of the engaging portion 43 relative to the extending direction of the spring portion 42 are set. When the aforementioned retaining ring (not shown) is assembled to the first intermediate gear shaft 23, in the fixed and engaged states of the force-applying spring 41, the retaining ring contacts the outer surface of the support protrusion 141. According to the backlash reduction mechanism described later, it is preferable that the engagement groove 43a of the engagement portion 43, in the fixed state of the force spring 41, extends in a direction orthogonal or substantially orthogonal to the central axis of the first intermediate gear shaft 23. It should be noted that the force spring 41 can also restrict the movement of the first intermediate gear shaft 23 in the central axial direction, therefore, the retaining ring can be omitted as described above.

[0154] like Figure 5 , 6 As shown in Figures 11 and 14, the leaf spring 9 and the force-applying spring 41 are integrally formed as a single component. Specifically, the other end 9b of the leaf spring 9 and the fixing portion 44 of the force-applying spring 41 are integrally formed from the same component. That is, the leaf spring 9 and the force-applying spring 41 are formed from a continuous elastic component, and the other end 9b of the leaf spring 9 and the fixing portion 44 of the force-applying spring 41 are formed in the same part of the continuous elastic component.

[0155] Next, the function of the force application mechanism 40 of the absolute encoder 2 will be explained.

[0156] In the absolute encoder 2, the main shaft end 23a of the first intermediate gear shaft 23 is inserted into the through hole 143 formed in the support protrusion 131 of the base 3, and the secondary shaft end 23b is inserted into the through hole 145 formed in the support protrusion 141 of the base 3 and is supported by the base 3. Thus, the first intermediate gear shaft 23 is supported by the support protrusions 131 and 141.

[0157] Thus, the first intermediate gear 20 is rotatable, supported by the first intermediate gear shaft 23. Furthermore, due to the action of the leaf spring 9, the first intermediate gear 20 is forced towards the support protrusion 141, and the sliding portion 26 on the secondary shaft side of the first intermediate gear 20 abuts against the inner surface 141a of the support protrusion 141 (see reference). Figure 13 ).

[0158] As described above, the long axis of the through hole 145, which is elongated in shape and supports the secondary shaft end 23b of the first intermediate gear shaft 23, is longer than the short axis. The secondary shaft end 23b is supported so that it can move along the long axis of the through hole 145, that is, along the horizontal plane within the width of the long axis of the through hole 145. On the other hand, the through hole 143 of the main shaft end 23a of the first supporting intermediate gear shaft 23 is circular. Therefore, in the absolute encoder 2, the intermediate gear shaft 23 can swing along the horizontal plane with the support portion of the main shaft end 23a as the center or approximately the center, through the through holes 143 and 145 of the support protrusions 131 and 141 and the force application mechanism 40.

[0159] Furthermore, for the first intermediate gear shaft 23 thus supported, the engaging portion 43 of the force spring 41 engages with the engaging groove 23d of the secondary shaft side end 23b. The force spring 41 applies force to the secondary shaft side end 23b of the first intermediate gear shaft 23 by pushing the second worm portion 22 of the first intermediate gear 20 toward the second worm gear portion 31 of the secondary shaft gear 30 (second meshing direction P2). As a result, the second worm portion 22 of the first intermediate gear 20 is pressed against the second worm gear portion 31 of the first secondary shaft gear 30, and the second worm portion 22 and the second worm gear portion 31 cause a so-called bottoming-out phenomenon, and the backlash between the gears becomes zero.

[0160] Furthermore, the secondary shaft end 23b of the first intermediate gear shaft 23, which is supported as a swingable shaft, is subjected to force by the force-applying spring 41. Therefore, during swinging, the first intermediate gear shaft 23 is continuously subjected to force in the direction from the second worm portion 22 toward the second worm wheel portion 31. Thus, the backlash between the second worm portion 22 and the second worm wheel portion 31 is always zero, preventing adverse conditions caused by the swinging of the first intermediate gear shaft 23.

[0161] For example, when the ambient temperature around the absolute encoder 2 is high, the first counterspindle gear 30 expands according to the linear expansion coefficient of the material, and the pitch circle of the gear in the second worm gear portion 31 enlarges. At this time, if the through hole 145 formed in the support protrusion 141 of the base 3 is not an elongated hole but a circular hole as in this embodiment, the counterspindle end 23b of the first intermediate gear shaft 23 is fixed by the through hole 145, and the first intermediate gear shaft 23 cannot swing as in this embodiment. Therefore, due to the increased temperature and the enlarged pitch circle of the gear, the second worm gear portion 31 of the first counterspindle gear 30 sometimes contacts the second worm portion 22 of the first intermediate gear 20 with a relatively strong force, and the gear will not rotate.

[0162] Conversely, when the ambient temperature around the absolute encoder 2 is low, the first counterspindle gear 30 contracts according to the linear expansion coefficient of the material, and the pitch circle of the gear in the second worm gear portion 31 shrinks. At this time, if the through hole 145 formed in the support protrusion 141 of the base 3 is not an elongated hole but a circular hole as in this embodiment, the counterspindle end 23b of the first intermediate gear shaft 23 is fixed by the through hole 145, and the first intermediate gear shaft 23 cannot swing as in this embodiment. In this case, the backlash between the second worm portion 22 of the first intermediate gear 20 and the second worm gear portion 31 of the first counterspindle gear 30 increases, and the rotation of the first intermediate gear 20 is not transmitted to the first counterspindle gear 30 with high precision.

[0163] In contrast, in the absolute encoder 2 of this embodiment, as described above, the first intermediate gear shaft 23 is supported so that it can swing horizontally about the support portion of the main shaft side end 23a as a center or approximately the center, and the first intermediate gear 20 is always subjected to force from the second worm portion 22 side to the second worm wheel portion 31 side by the force application mechanism 40. Furthermore, the first intermediate gear 20 supported by the first intermediate gear shaft 23 is subjected to force by the leaf spring 9 toward the support protrusion 141. Therefore, even if the pitch circle of the gear in the second worm wheel portion 31 of the first counterspindle gear 30 changes due to changes in ambient temperature as described above, the backlash is zero while the tooth surfaces of the second worm portion 22 and the second worm wheel portion 31 are always in contact with appropriate pushing force. Therefore, it is possible to avoid the gear not rotating due to temperature changes, or the deterioration of the accuracy of the rotation transmitted from the first intermediate gear 20 to the first counterspindle gear 30.

[0164] Therefore, the impact of backlash in the reduction mechanism of the absolute encoder 2 on detection accuracy can be reduced. As a result, the resolution of the measurable rotation amount of the spindle 1a can be maintained, and the range of measurable rotation amounts of the spindle 1a can be expanded.

[0165] It should be noted that, preferably, the force application mechanism 40 is configured to generate a constant or substantially constant pushing force by the force application spring 41, regardless of the position of the secondary shaft end 23b of the first intermediate gear shaft 23 caused by the oscillation.

[0166] As described above, the through hole 143 of the support protrusion 131 at the main shaft end 23a supporting the first intermediate gear shaft 23 is a circular hole, and the through hole 145 of the support protrusion 141 at the secondary shaft end 23b is an elongated hole with a wider width on the long shaft side than on the short shaft side. The first intermediate gear shaft 23 can swing parallel or approximately parallel to the horizontal direction with the through hole 143 of the support protrusion 131 as the fulcrum. Therefore, during the swing of the first intermediate gear shaft 23, the movement of the second worm portion 22 relative to the second worm gear portion 31 is greater than the movement of the first worm gear portion 21 relative to the first worm portion 11. Even if the second worm portion 22 and the second worm gear portion 31 touch the bottom, the first worm portion 11 and the first worm gear portion 21 will not touch the bottom.

[0167] like Figures 10-13 As shown, the through hole 145 supporting the first intermediate gear shaft 23 at the secondary shaft end 23b forms a cylindrical or generally cylindrical surface, but the through hole 145 is not limited to having such a shape. For example, as Figure 25 As shown, the through hole 145 can also be a rectangular or approximately rectangular hole with a cross-sectional shape that is not elongated. That is, the through hole 145 can be a through hole forming two opposing pairs 145a and 145b, extending in a prismatic shape. The opposing pairs 145a and 145b forming the through hole 145 can be either planar or curved surfaces. In the absolute encoder 2, one pair 145a extends horizontally, and the other pair 145b extends vertically. The horizontal width of the surface 145a is longer than the vertical width of the surface 145b. Figure 25 The through hole 145 shown can also allow the first intermediate gear shaft 23 to swing in the same way as the through hole 145 described above.

[0168] Similarly, the through hole 143 is not limited to a hole having the shape described above. For example, the through hole 143 can also be a hole with a so-called blade structure. Specifically, the through hole 143 can be a hole that contacts the first intermediate gear shaft 23 through line contact or point contact. For example, as Figure 26As shown in (a) and (b), the through hole 143 can be a hole formed by a pair of conical or substantially conical inclined surfaces 143c that taper in diameter toward the inner side in the extending direction of the through hole 143. In this case, at the annular line (connecting line 143d) depicting the portion of the circular hole where the pair of inclined surfaces 143c connect, the through hole 143 contacts and supports the first intermediate gear shaft 23. The shape of the circular hole in the connecting line 143d, when viewed from above, has the same shape as the circular hole shape of the through hole 143 described above. The through hole 143 supports the first intermediate gear shaft 23 through line contact or point contact, so even if the diameter of the circular hole of the through hole 143 is made closer to the diameter of the first intermediate gear shaft 23, the first intermediate gear shaft 23 can still swing. Therefore, the cross-sectional shape of the through hole 143 can be made close to a shape without a gap between the through hole 143 and the first intermediate gear shaft 23. Therefore, when the first intermediate gear shaft 23 oscillates, the movement of the portion of the first intermediate gear shaft 23 in contact with the through hole 143 can be suppressed, and the change in the distance between the first worm portion 11 and the first worm wheel portion 21 due to the oscillation of the first intermediate gear shaft 23 can be suppressed. It should be noted that the through hole 145 of the support protrusion 141, like the through hole 143 of the support protrusion 131 described above, can be a hole with a so-called blade structure, for example, it can be a hole formed by a pair of conical or substantially conical inclined surfaces forming a ring-shaped line depicting an elongated hole.

[0169] In addition, such as Figure 27 As shown in (a) and (b), the through hole 145 can be formed by a pair of pyramidal or substantially pyramidal inclined surfaces 145e that taper towards the inward side in the extending direction of the through hole 145. In this case, the through hole 145 contacts and supports the first intermediate gear shaft 23 at the annular line (connecting line 145f) depicting the portion where the pair of inclined surfaces 145e connect. The connecting line 145f has line portions 145g and 145h, which are a pair of opposing parts. The pair of line portions 145g and 145h can be either straight lines or curves. In the absolute encoder 2, the pair of line portions 145g extends horizontally, and the pair of line portions 145h extends vertically. The length of the line portion 145g is longer than the vertical length of the line portion 145h. It should be noted that, like the through hole 145 of the support protrusion 142 described above, the through hole 143 of the support protrusion 131 can be formed by a pair of inclined surfaces in the shape of a quadrangular pyramid or approximately quadrangular pyramid, forming a ring-shaped line depicting a quadrangular or approximately quadrangular shape. In this case, the ring-shaped line is square or approximately square. In this case, it is also consistent with the above... Figure 26Similarly, the through hole 143 supports the first intermediate gear shaft 23 through line contact or point contact. Therefore, even if the line portion extending in the vertical direction (and) Figure 27 The length of the line portion 145h (corresponding to) and the line portion extending horizontally (with) Figure 27 The length of the wire portion 145g is closer to the diameter of the first intermediate gear shaft 23, allowing the first intermediate gear shaft 23 to swing. Therefore, the shape of the through hole 143 can be made close to a shape without vertical and horizontal gaps between the through hole 143 and the first intermediate gear shaft 23. Consequently, when the first intermediate gear shaft 23 swings, movement of the portion of the first intermediate gear shaft 23 in contact with the through hole 143 can be suppressed, and the distance between the first worm portion 11 and the first worm wheel portion 21 can be suppressed from changing due to the swinging of the first intermediate gear shaft 23.

[0170] (Control Department) Next, the control unit of the absolute encoder 2 will be explained. Figure 28 Viewed from the lower surface 5a side Figure 2 The diagram shows a substrate 5. A microcomputer 51, a line driver 52, a bidirectional driver 53, and a connector 6 are mounted on the substrate 5. The microcomputer 51, line driver 52, bidirectional driver 53, and connector 6 are electrically connected via patterned wiring on the substrate 5.

[0171] The bidirectional driver 53 enables bidirectional communication with an external device connected to the connector 6. The bidirectional driver 53 converts data such as operating signals into differential signals for communication with the external device. The line driver 52 converts data representing the amount of rotation into differential signals and outputs these differential signals to the external device connected to the connector 6 in real time. The connector 6 is a connector to which an external device is connected.

[0172] Figure 29 It is a general representation Figure 1 The diagram shows the functional composition of the absolute encoder 2. Figure 29 The modules of the microcomputer 51 shown represent the functions implemented by the CPU (Central Processing Unit) of the microcomputer 51 executing programs.

[0173] The microcomputer 51 includes a rotation angle acquisition unit 51p, a rotation angle acquisition unit 51q, a rotation angle acquisition unit 51r, a table processing unit 51b, a rotation amount determination unit 51c, and an output unit 51e. The rotation angle acquisition unit 51p acquires the rotation angle Ap of the main shaft gear 10 based on a signal output from the angle sensor Sp. The rotation angle Ap is angle information representing the rotation angle of the main shaft gear 10. The rotation angle acquisition unit 51q acquires the rotation angle Aq of the first countershaft gear 30 based on a signal output from the magnetic sensor Sq. The rotation angle Aq is angle information representing the rotation angle of the first countershaft gear 30. The rotation angle acquisition unit 51r acquires the rotation angle Ar of the magnet holder 61, i.e., the second countershaft gear 63, based on a signal output from the magnetic sensor Sr. The rotation angle Ar is angle information representing the rotation angle of the second countershaft gear 63.

[0174] The table processing unit 51b refers to a first correspondence table storing the rotational speeds of the main shaft gear 10 corresponding to the rotational angles Aq of the first counterspindle gear 30 and Ar of the second counterspindle gear 63, and determines the rotational speeds of the main shaft gear 10 corresponding to the acquired rotational angles Aq and Ar. The rotation amount determination unit 51c determines the rotational amount of the main shaft gear 10 after multiple rotations based on the number of rotations of the main shaft gear 10 (main shaft 1a) determined by the table processing unit 51b and the acquired rotational angle Ap. The output unit 51e converts the rotational amount of the main shaft gear 10 after multiple rotations determined by the rotation amount determination unit 51c into information representing that rotational amount and outputs it.

[0175] (Housing and shielding components) Figure 30 This is a perspective view that roughly represents the structure of the housing 4 and shielding member 7 of the absolute encoder 2. Figure 31 This is a top view that roughly represents the configuration of the shielding member 7 of the absolute encoder 2.

[0176] Reference Figure 30 and Figure 31 The structure of the shielding member 7 will be described in detail. The shielding member 7 mainly includes a shielding member body 711, a flat part 721, an outer peripheral part 731, a protrusion 77, an outer surface part 741, a curved surface part 751, and a through hole 761.

[0177] The shielding member body 711 is a magnetic component constituting the shielding member 7. The shielding member body 711 has a shape corresponding to the shape of the cover portion 4b, specifically, for example, a flat plate-shaped component, so as to cover the cover portion 4b of the housing 4. The planar portion 721 is a plane extending along the X-axis and Y-axis in the shielding member body 711. The outer peripheral portion 731 corresponds to the end of the outer peripheral side of the planar portion 721.

[0178] The protrusion 77 extends outward from the outer periphery 731a on the X-axis side of the shielding member body 711. Figure 30 The protrusion 77 protrudes along the X-axis. The amount of protrusion along the X-axis from the outer periphery 731a of the protrusion 77 is determined based on the depth of the outer side of the recess 4e along the X-axis. The length (width) of the protrusion 77 along the Y-axis corresponds to the length (width) of the recess 4e along the Y-axis. The width of the protrusion 77 is determined based on the thickness of the shielding member 7.

[0179] The outer surface portion 741 is located on the outer side of the protrusion 77 in the width direction (Y-axis). By providing the outer surface portion 741, as... Figure 31 As shown, the protrusion 77 is configured to be surrounded by the outer surface portion 741 along the Y-axis. Figure 30 As shown, the outer surface 741 is the side surface 41d facing the outer side (Y-axis side) of the recess forming portion 4d in the width direction when the shielding member 7 is assembled in the housing 4.

[0180] A curved portion 751 is provided on the outer peripheral portion 731b of the shielding member body 711 on the side opposite to the position where the protrusion 77 is provided. The curved portion 751 is bent at a right angle or approximately a right angle relative to the flat portion 721 downwards (-Z axis) along the side wall portion, i.e., the outer wall portion 4a, of the housing 4. A through hole 761 is a hole formed in the curved portion 751 that extends through the thickness direction of the shielding member body 711. The through hole 761 is formed at a position corresponding to the threaded hole 4f of the housing 4 when the shielding member 7 is assembled to the housing 4.

[0181] Figure 32 This is a side view taken along the X-axis, which is a schematic representation of the configuration of the housing 4 of the absolute encoder 2. Figure 33 This is a cross-sectional view taken along the Y-axis, which is a schematic representation of the structure of the housing 4.

[0182] Apart from Figure 30 In addition, refer to Figure 32 , 33 The structure of the housing 4 will be described in detail. The housing 4 of the absolute encoder 2 mainly includes an outer wall portion 4a, a cover portion 4b, a recess forming portion 4d, a recess 4e, and a threaded hole 4f. The housing 4 has a roughly cuboid shape that is flat in the X and Y axes, with its length in the height direction (Z-axis) being shorter than its length in the depth direction (X-axis) and width direction (Y-axis).

[0183] Multiple (e.g., four) outer wall portions 4a are provided in the housing 4. The outer wall portions 4a at least sideways (X-axis or Y-axis) surround a portion of the main shaft 1a of the motor 1, the main shaft gear 10, and the first intermediate gear 20. Cover portions 4b are integrally formed with the outer wall portions 4a at the upper ends of the four outer wall portions 4a of the housing 4. The outer wall portions 4a and cover portions 4b define the approximate rectangular shape of the housing 4. Spaces are formed inside the outer wall portions 4a and cover portions 4b to accommodate the aforementioned components such as a portion of the main shaft 1a of the motor 1 and the main shaft gear 10 and first intermediate gear 20 of the absolute encoder 2.

[0184] The recess forming portion 4d protrudes upward from the outer side of the cover portion 4b, which corresponds to the upper surface portion of the housing 4, for example, at the end in the -X axis (+Z axis). The recess forming portion 4d has a generally cuboid shape that is flat in the X and Y axes, with a length in the height direction (Z axis) shorter than its length in the depth direction (X axis) and width direction (Y axis). The shape of the recess forming portion 4d is not limited to any shape that can form the recess 4e. Figure 30 Examples are shown. A recess 4e is formed on the inner side (-X axis side) of the recess forming portion 4d.

[0185] The recess 4e is located on the outer side of the cover 4b of the housing 4. Figure 30 A recessed portion 4d is formed at the end of the recess 4e along the -X axis. Regarding the groove of the recess 4e, in the direction of the surface of the cover portion 4b of the housing 4, in... Figure 30 The X-axis represents the depth direction. The recess 4e faces the inside of the housing 4 within the recess forming portion 4d. Figure 30 The central X-axis opens upward toward the center of the housing 4. The recess 4e accommodates the protrusion 77 inserted outward from the center of the housing 4. A side wall portion 41e and an upper wall portion 42e are formed in the recess 4e.

[0186] The sidewall portion 41e is a wall-like part extending along the height direction (Z-axis) outward from the width direction (Y-axis) of the recess 4e. Multiple sidewall portions 41e with different widths (lengths along the Y-axis) are provided in the recess 4e. The width of the multiple sidewall portions 41e is set according to the width of the protrusions 77 of the shielding member 7, which has a different plate thickness.

[0187] The upper wall portion 42e is a wall-shaped part extending along the width direction of the recess 4e. Multiple upper wall portions 42e with different heights from the cover portion 4b are provided in the recess 4e. The height of the upper wall portion 42e from the cover portion 4b is set according to the height (thickness of the shielding member 7) of the protrusions 77 of multiple shielding members 7 with different plate thicknesses.

[0188] The threaded hole 4f is a hole in the housing 4 with an internal thread formed on the outer wall portion 4a on the side opposite to where the recess 4e is located. The threaded hole 4f communicates with the through hole 761 of the shielding member 7 when the shielding member 7 is assembled in the housing 4. The number, position, and diameter of the threaded holes 4f are not limited. Figure 30 Examples are shown below.

[0189] Next, the relationship between the protrusion 77 and the recess 4e when the shielding member 7 is assembled into the housing 4 will be explained.

[0190] Figure 34 This is a schematic diagram showing the state in which the protrusion 77 of the shielding member 7 is inserted into the recess 4e of the housing 4 of the absolute encoder 2.

[0191] like Figure 34 As shown, when the shielding member 7 is assembled into the housing 4, the flat portion 721 of the shielding member 7 is moved upward along the X-axis along the cover portion 4b of the housing 4. By moving the shielding member 7 in this way, the protrusion 77 is inserted into the recess 4e. Here, the width of the side wall portion 41e of the lowermost section (the side closest to the cover portion 4b) of the recess 4e is formed corresponding to the width of the protrusion 77 of the shielding member 7. The height of the upper wall portion 42e of the lowermost section of the recess 4e is formed corresponding to the plate thickness of the shielding member 7. Furthermore, in the shielding member 7, the outer surface portion 741 of the protrusion 77, located on the outer side in the width direction, is formed corresponding to the width of the outer surface of the recess forming portion 4d of the housing 4.

[0192] By forming the housing 4 and the shielding member 7 as described above, the positioning of the shielding member 7 relative to the housing 4 in the absolute encoder 2 becomes easy in the X-axis, Y-axis and Z-axis directions.

[0193] Furthermore, in the absolute encoder 2, a curved portion 751 is provided on the outer peripheral portion 731b opposite to the side where the protrusion 77 is formed in the X-axis direction, forming along the outer wall portion 4a of the housing 4. This curved portion 751 facilitates the positioning of the shielding member 7 in the X-axis direction. Additionally, the curved portion 751 has a through hole 761 through which a screw 78 for fixing the shielding member 7 to the housing 4 is inserted. By inserting the screw 78 through the through hole 761 and fixing it to the threaded hole 4f provided in the outer wall portion 4a of the housing 4, the shielding member 7 can be reliably fixed to the housing 4 according to the absolute encoder 2.

[0194] Figure 35 This is a top view that roughly shows the configuration of the shielding member 7B of the absolute encoder 2. Figure 36 This is a schematic diagram showing the state in which the protrusion 77B of the shielding member 7B is inserted into the recess 4e of the housing 4 of the absolute encoder 2. Figure 37This is a perspective view that schematically represents the configuration of an absolute encoder 2 equipped with a shielding member 7B.

[0195] Figures 35-37 The shielding member 7B shown differs from the shielding member 7 previously described in the following aspects: The plate thickness of the shielding member body 711B is greater than that of the shielding member 7. Furthermore, the length (width) of the protrusion 77B in the Y-axis direction of the shielding member 7B is narrower than the width of the protrusion 77 of the shielding member 7.

[0196] like Figure 36 As shown, when the shielding member 7B is assembled onto the housing 4, the flat portion 721B of the shielding member 7B moves along the cover portion 4b of the housing 4. The width of the third section of the side wall portion 41eb from below the recess 4e corresponds to the width of the protrusion 77B of the shielding member 7B. The height of the second section of the upper wall portion 42eb from below the recess 4e corresponds to the plate thickness of the shielding member 7B.

[0197] By forming the housing 4 and the shielding member 7B as described above, in the absolute encoder 2, the positioning of the shielding member 7B relative to the housing 4 in the X-axis, Y-axis and Z-axis becomes easy, similar to the shielding member 7 described previously.

[0198] Figure 38 This is a top view that roughly shows the structure of the shielding member 7C of the absolute encoder 2. Figure 39 This is a schematic diagram showing the state in which the protrusion 77C of the shielding member 7C is inserted into the recess 4e of the housing 4 of the absolute encoder 2. Figure 40 This is a perspective view that schematically represents the configuration of an absolute encoder 2 equipped with a shielding member 7C.

[0199] Figures 38-40 The shielding member 7C shown differs from the shielding members 7 and 7B described previously in the following aspects: The plate thickness of the shielding member body 711C is greater than that of the shielding members 7 and 7B. Furthermore, the length (width) of the protrusion 77C in the Y-axis of the shielding member 7C is narrower than the width of the protrusion 77 of the shielding member 7 and the protrusion 77B of the shielding member 7B.

[0200] like Figure 39 As shown, when the shielding member 7C is assembled onto the housing 4, the planar portion 721C of the shielding member 7C moves along the cover portion 4b of the housing 4. The width of the side wall portion 41ec, the uppermost section (farthest from the cover portion 4b) from below the recess 4e, is formed corresponding to the width of the protrusion 77C of the shielding member 7C. The height of the upper wall portion 42ec of the uppermost section of the recess 4e is formed corresponding to the plate thickness of the shielding member 7C.

[0201] By forming the housing 4 and the shielding member 7C as described above, in the absolute encoder 2, the positioning of the shielding member 7C relative to the housing 4 in the X-axis, Y-axis, and Z-axis becomes easy, similar to the shielding members 7 and 7B described previously.

[0202] In other words, in the absolute encoder 2, the combination of multiple sidewall portions 41e with different widths and multiple upper wall portions 42e with different heights located in the recess 4e of the housing 4 is set according to the width of the protrusions 77, 77B, and 77C of the shielding members 7, 7B, and 7C with different plate thicknesses. As the plate thickness increases, the magnetic shielding effect of the shielding members 7, 7B, and 7C on the angle sensors Sp, Sq, and Sr of the housing 4 from the outside improves. Therefore, with the absolute encoder 2 configured in this way, shielding members 7, 7B, and 7C of various plate thicknesses can be easily selected according to the performance requirements of the shielding effect for various main reasons, such as the use of magnetic sensors with different performance characteristics.

[0203] Figure 41 This is a perspective view illustrating the configuration of an absolute encoder 200, a modified embodiment of the present invention. Figure 41 In this case, the housing 400 and shielding member 700 of the absolute encoder 200 are constructed differently from the housing 4 and shielding members 7, 7B and 7C described previously in the following aspects.

[0204] The housing 400 differs from the previously described housing 4 in that it has a boss portion 401 protruding upward from the cover portion 4b (+Z axis) and in that the outer wall portion 4a does not have a threaded hole 4f. The shielding member 700 differs from shielding members 7, 7B, and 7C in that it has a boss hole 701 that can accommodate the boss portion 401 and in that it does not have a curved surface portion 751 and a through hole 761.

[0205] In the absolute encoder 2 described earlier, the shielding members 7, 7B, and 7C are positioned relative to the housing 4 in the X-axis direction by the curved surface 751 and the outer wall portion 4a. On the other hand, in the absolute encoder 200, the shielding member 700 is positioned relative to the housing 400 in the X-axis direction by the boss portion 401 of the housing 400 and the boss hole 701 of the shielding member 700.

[0206] In the absolute encoder 200 described above, as in the absolute encoder 2 described previously, the positioning of the shielding member 700 relative to the housing 400 in the X-axis, Y-axis, and Z-axis becomes easier.

[0207] In particular, the absolute encoder 200 has a boss portion 401 protruding upward (+Z axis) on the cover portion 4b of the housing 4. Furthermore, the absolute encoder 200 has a boss hole 701 at a position corresponding to the boss portion 401 of the flat portion 721 of the shielding member 700, which engages with the boss portion 401. With such a boss portion 401 and boss hole 701, positioning of the shielding member 700 in the X-axis becomes easier. The boss portion 401 and boss hole 701 are fixed by embedding during assembly using the flexibility of the housing 400 and the shielding member 700. With this configuration, the shielding member 700 can be reliably fixed to the housing 400 with a simple configuration according to the absolute encoder 200.

[0208] The embodiments of the present invention have been described above, but the present invention includes all the concepts and solutions encompassed by the claims and is not limited to the absolute encoder 2 of the embodiments described above. Furthermore, in order to achieve at least some of the aforementioned problems and effects, the various components can be selectively combined or combined with known technologies. For example, the shape, material, arrangement, size, etc., of each component in the above embodiments can be appropriately modified according to the specific application scheme of the present invention. Explanation of reference numerals in the attached figures

[0209] 1: Motor; 1a: Spindle; 1b: Press-in part; 2: Absolute encoder; 3: Base; 3a: Support plate; 4: Housing; 4a: Outer wall; 4b: Cover; 4c: Claw; 4d: Recess forming part; 4e: Recess; 4f: Threaded hole; 5: Base plate; 5a: Lower surface; 5b: Positioning hole; 6: Connector; 7: Shielding member; 7B: Shielding member; 7C: Shielding member; 8a: Screw; 8b: Screw; 8c: Screw; 9: Leaf spring; 9a: One end; 9b: The other end; 10: Spindle gear; 11: First worm gear part; 12: Spindle connector; 12a: Upper end face; 13: Cylindrical part; 13a: Upper end face; 14: Press-in part; 15: Magnet holding part; 15a: Inner circumferential surface; 15b: Bottom surface; 20: 21: First intermediate gear; 22: Second worm gear; 23: First intermediate gear shaft; 23a: Main shaft side end; 23b: Secondary shaft side end; 23c: Groove; 23d: Engaging groove; 24: Cylindrical part; 24a: Through hole; 24b: Inner circumferential surface; 25: Main shaft side sliding part; 26: Secondary shaft side sliding part; 30: First secondary shaft gear; 31: Second worm gear; 32: Gear part; 33: Through hole; 35: Magnet retainer; 35a: Magnet retainer; 35b: Shaft part; 35c: Bearing stop; 35d: Bearing positioning member; 40: Force application mechanism; 41: Force application spring; 41d: Side; 41e: Side wall part; 41eb: Side wall part; 41ec: Side wall part; 42: Spring part ; 42e: Upper wall portion; 42eb: Upper wall portion; 42ec: Upper wall portion; 43: Engaging portion; 43a: Engaging groove; 43b: Top edge; 43c: Connecting portion; 44: Fixing portion; 44a: Hole; 45: Support protrusion; 45a: Support surface; 51: Microcomputer; 51b: Table processing unit; 51c: Rotation amount determination unit; 51e: Output unit; 51p: Rotation angle acquisition unit; 51q: Rotation angle acquisition unit; 51r: Rotation angle acquisition unit; 52: Line driver; 53: Bidirectional driver; 60: Magnetic detection device; 61: Magnet holding member; 62: Second countershaft gear shaft; 62a: Lower end face; 62b: Upper end face; 62c: Groove; 62d: Retaining ring; 62e: Conical part; 62f: One end; 62g: Peripheral surface; 62h: Connecting part; 63: Second countershaft gear; 64: Gear part; 65: Magnet holding part; 65a: Insertion part; 65b: Magnet receiving part; 66: Main body part; 66a: Through hole; 66b: Lower end face; 66c: Upper end face; 67: Magnet support part; 67a: Inner peripheral surface; 67b: Outer peripheral surface; 67c: Upper end face; 68: Cylindrical part; 68a: Inner peripheral surface; 68b: Inner peripheral surface; 68c: Open end; 68d: Closed end; 68e: Outer peripheral surface; 69: Bottom; 69a: Bottom surface; 69b: Opening part; 70: Second intermediate gear; 711: Shielding component main body; 71: Gear part; 711B: Shielding component main body; 711C: Shielding component main body; 72: Gear part;73: Main body; 73a: Lower end face; 73b: Upper end face; 74: Through hole; 75: Shaft; 75a: Lower end face; 75b: Upper end face; 75c: Groove; 76: Retaining ring; 77: Protrusion; 77B: Protrusion; 77C: Protrusion; 78: Screw; 100: Shielding member; 101: Base; 102: Lower surface; 103: Recess; 104: Upper surface; 105: Outer peripheral surface; Right outer peripheral surface; 106: Rear outer peripheral surface; 107: Left outer peripheral surface; 108: Front outer peripheral surface; 110: Substrate support; 111: Upper end face; 112: Threaded hole; 120: Substrate positioning pin; 121: Top end; 122: Base; 123: Stepped surface; 124: One end; 125: The other end; 126: tapered face; 126a: connecting part; 127: tapered face; 127a: connecting part; 128: through hole; 128a: first hole; 128b: end; 128c: second hole; 129: circumferential surface; 131: support protrusion; 131a: outer surface; 132: support protrusion; 132a: protrusion; 134: bearing retainer; 135: bearing; 136: shaft support; 136a: through hole; 137: shaft support; 137a: through hole; 141: support protrusion; 141a: inner surface; 142: support protrusion; 143: through hole; 143c: inclined surface; 143d: connecting line; 144: retaining ring; 145: through hole; 1 45a: Surface; 145b: Surface; 145e: Inclined surface; 145f: Connecting line; 145g: Line part; 145h: Line part; 200: Absolute encoder; 400: Housing; 401: Boss part; 700: Shielding member; 701: Boss hole; 721: Flat part; 721B: Flat part; 721C: Flat part; 731: Outer peripheral part; 731a: Outer peripheral part; 731b: Outer peripheral part; 741: Outer side surface; 751: Curved surface; 761: Through hole; Ap: Angular information; Aq: Angular information; BC: Bearing central axis; GC1: Main shaft gear central axis; GC2: First secondary shaft gear central axis; GC3: Central axis; GC4: Central axis; MoC: Horse The central axis of the main spindle; Mp: magnet; MPa: upper surface; Mpb: lower surface; MpC: central axis of the magnet; Mpd: outer peripheral surface; Mq: magnet; Mqa: upper surface; Mqb: lower surface; MqC: central axis of the magnet; Mqd: outer peripheral surface; Mr: magnet; Mra: upper surface; Mrb: lower surface; MrC: central axis of the magnet; Mrd: outer peripheral surface; P: direction of force application; P1: first meshing direction; P2: second meshing direction; R1: first speed change mechanism; R2: second speed change mechanism; SaC: central axis of the main spindle joint; SC: central axis of the magnet retainer; Sp: angle sensor; Sq: angle sensor; Sr: angle sensor; XYZ: orthogonal coordinate system.

Claims

1. A magnetic detection device, comprising: A magnetized magnet; A magnetic sensor senses the magnetic flux from the magnet; A magnet holder for holding the magnet; axis; The housing has multiple sidewall portions and a top surface portion, and internally accommodates the magnet and the magnetic sensor; as well as A flat shielding member, having a planar portion with a shape corresponding to the upper surface portion, is assembled onto the upper surface portion. The shielding member has a protrusion that protrudes outward from the outer periphery of the planar portion. The housing has an inwardly opening recess at the outer end of the upper surface portion to accommodate the protrusion. The recess has multiple sidewalls of different widths and multiple upper wall portions of different heights. The shielding member has: a curved portion, wherein the outer peripheral portion on the opposite side to the location where the protrusion is provided in the flat portion is bent at a right angle or approximately a right angle relative to the flat portion along the side wall portion of the housing; and a through hole formed in the curved portion. The housing has a threaded hole, which communicates with the through hole on the side wall portion opposite to the location where the recess is provided.

2. The magnetic detection device according to claim 1, wherein, The height of the plurality of upper wall portions is set according to the height of the protrusions of the plurality of shielding members with different plate thicknesses. The width of the plurality of sidewall portions is set according to the width of the protrusions of the plurality of shielding members with different plate thicknesses.

3. The magnetic detection device according to claim 1, wherein, The housing has a recess forming portion that protrudes upward from the outer end of the upper surface portion to form the recess. The shielding member has an outer face facing the recessed portion on the outer side of the convex portion in the width direction.

4. The magnetic detection device according to any one of claims 1 to 3, wherein, The housing has a boss portion that protrudes upward from the upper surface portion. The shielding member has a boss hole for accommodating the boss portion.

5. An absolute encoder comprising the magnetic detection device according to any one of claims 1 to 4.

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