JP7262276B2 - absolute encoder - Google Patents

Description

The present invention relates to absolute encoders.

2. Description of the Related Art Conventionally, rotary encoders are known that are used to detect the position and angle of movable elements in various types of control machinery. Such rotary encoders include incremental encoders that detect relative positions or angles and absolute encoders that detect absolute positions or angles. As such an absolute encoder, for example, an absolute encoder has been disclosed that includes a magnetic encoder device having a gear mechanism and an optical encoder device that is configured using a single rotating disk ( For example, see Patent Document 1).

JP 2013-24572 A

In such a conventional absolute encoder, it is necessary to appropriately arrange the magnetic encoder device in order to specify the amount of rotation over multiple rotations of the main shaft (main shaft). However, in conventional absolute encoders, if the size of the absolute encoder is reduced, considering the influence of magnetic interference, etc., multiple magnetic encoder devices and sub shafts (secondary shafts) must be arranged in addition to the main shaft magnetic encoder device. Can not do it. Therefore, there is a problem that the amount of rotation of the main shaft that can be detected cannot be increased by increasing the number of sub-shafts.

On the other hand, considering the detection accuracy of the angle sensor of the magnetic encoder device, backlash of the reduction gear, temperature characteristics, etc., there is a limit to the amount of rotation of the main shaft (main shaft) that can be detected by a single angle sensor. Therefore, there is a problem that the amount of rotation of the main shaft that can be detected cannot be increased. Thus, a conventional absolute encoder is required to have a structure capable of increasing the amount of rotation of the main shaft that can be detected even when the absolute encoder is downsized.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its object is to provide an absolute encoder capable of increasing the detectable rotation amount of a main shaft even when the absolute encoder is downsized. be.

To achieve the above object, an absolute encoder according to the present invention is an absolute encoder that specifies a rotation amount over a plurality of rotations of a main shaft, comprising: a first drive gear that rotates according to the rotation of the main shaft; A first driven gear that meshes with the drive gear, a second driven gear that rotates according to the rotation of the first driven gear, a second driven gear that meshes with the second driven gear, and a sub that rotates according to the rotation of the second driven gear. and a counting mechanism for specifying the number of revolutions of the shaft gear.

In the absolute encoder according to one aspect of the present invention, the counting mechanism includes a third driving gear that rotates according to the rotation of the second driven gear, a third driven gear that meshes with the third driving gear, and the third driven gear. a first cam portion that rotates according to the rotation of the first cam portion; a rocking member that rocks between a first position and a second position according to the rotation of the first cam portion; and a detection unit that detects whether it is at the position or at the second position.

In the absolute encoder according to one aspect of the present invention, the swinging member is slidable with the first cam portion, and the first swinging portion swings as it slides with the first cam portion. , one end of which is connected to the first oscillating portion, and the other end of which moves between the first position and the second position according to the oscillating movement of the first oscillating portion. a second swinging portion having a swinging magnet, wherein the detecting portion is a Hall detector that detects whether the magnet is at the first position or at the second position.

The absolute encoder according to one aspect of the present invention further includes a second cam portion that rotates according to the rotation of the third driven gear, and the rocking member includes the first cam portion and the second cam portion in plan view. a third oscillating member extending so as to be sandwiched between the first oscillating portion, slidable with the second cam portion, and oscillating in accordance with sliding movement with the second cam portion; , and an elastic member for attracting the first swinging part and the third swinging part to each other.

In the absolute encoder according to one aspect of the present invention, the counting mechanism includes a third driving gear that rotates according to the rotation of the second driven gear, a third driven gear that meshes with the third driving gear, and the third driven gear. a first cam portion that rotates according to the rotation of the first cam portion; a slide member that slides between a first position and a second position according to the rotation of the first cam portion; and a switch section that is turned off at the first position and turned on at the second position.

The absolute encoder according to one aspect of the present invention further includes a first angle sensor that detects the rotation angle of the main shaft and a second angle sensor that detects the rotation angle of the sub shaft.

The absolute encoder according to one aspect of the present invention further includes an intermediate gear provided with the first driven gear and the second drive gear, wherein the rotation axis of the main shaft is at a twisted position with respect to the rotation axis of the intermediate gear. and is provided parallel to the rotation axis of the second driven gear.

According to the absolute encoder of the present invention, even if the absolute encoder is downsized, it is possible to increase the detectable rotation amount of the main shaft.

1 is a perspective view schematically showing the configuration of an absolute encoder according to an embodiment of the invention; FIG. 2 is a perspective view schematically showing the configuration of the absolute encoder shown in FIG. 1 with a case removed; FIG. FIG. 3 is a perspective view schematically showing the configuration of the absolute encoder shown in FIG. 2 with the substrate, control unit and connector removed; FIG. 4 is a perspective view schematically showing a state viewed from another angle in the configuration of the absolute encoder shown in FIG. 3; 5 is a perspective view schematically showing the configuration of the absolute encoder shown in FIG. 4 with the motor removed; FIG. 6 is a plan view schematically showing the configuration of the absolute encoder shown in FIG. 5; FIG. FIG. 2 is a cross-sectional view schematically showing a state cut along a plane passing through the center of a main shaft gear and perpendicular to an intermediate gear in the configuration of the absolute encoder shown in FIG. 1 with the motor removed; 8 is an exploded perspective view schematically showing an exploded state of a magnet, a main shaft gear, and a main shaft of a motor in the configuration of the absolute encoder shown in FIG. 7; FIG. FIG. 4 is a cross-sectional view schematically showing a state in which the configuration of the absolute encoder shown in FIG. 3 is cut along a plane that passes through the center of the intermediate gear and is parallel to the XY plane; 7 is a partial cross-sectional view schematically showing a state cut along a plane passing through the center of the intermediate gear and perpendicular to the XY plane in the configuration of the absolute encoder shown in FIG. 6; FIG. FIG. 3 is a partial cross-sectional view schematically showing a state cut along a plane that passes through the center of the countershaft gear and is perpendicular to the intermediate gear in the configuration of the absolute encoder shown in FIG. 2 ; FIG. 12 is an exploded perspective view schematically showing an exploded state of a magnet, a magnet holder, a countershaft gear and a bearing in the configuration of the absolute encoder shown in FIG. 11; FIG. 3 is a cross-sectional view schematically showing a state in which the configuration of the absolute encoder shown in FIG. 2 is cut along a plane passing through the centers of the counter shaft gear, the swing cam, and the swing member shaft; 14 is an exploded perspective view schematically showing an exploded state of the swing cam shaft and the swing cam in the configuration of the absolute encoder shown in FIG. 13; FIG. FIG. 2 is a cross-sectional view schematically showing a state in which a motor is removed from the configuration of the absolute encoder shown in FIG. 7 is a partial plan view schematically showing the configuration of a swing cam and a swing member of the absolute encoder shown in FIG. 6; FIG. 17 schematically shows an exploded state of the swing member shaft, the elastic member, the third swing portion, the first swing portion, the second swing portion, the magnet, and the magnet screw holder in the configuration of the absolute encoder shown in FIG. It is an exploded perspective view. FIG. 7 is a plan view schematically showing the configuration of the absolute encoder shown in FIG. 6 with a swing member removed; FIG. 19(a) is an enlarged view schematically showing the positions of the first oscillating portion in contact with the first cam portion and the third oscillating portion in contact with the second cam portion at address 0 of the absolute encoder shown in FIG. FIG. 19(b) is an enlarged plan view schematically showing the position of the second swinging portion when the positions of the first swinging portion and the third swinging portion are as shown in FIG. 19(a); be. FIG. 20(a) is an enlarged view schematically showing the positions of the first swinging portion in contact with the first cam portion and the third swinging portion in contact with the second cam portion at address 25 of the absolute encoder shown in FIG. FIG. 20(b) is an enlarged plan view schematically showing the position of the second oscillating portion when the positions of the first oscillating portion and the third oscillating portion are as shown in FIG. 20(a); be. FIG. 21(a) is an enlarged view schematically showing the positions of the first swinging portion in contact with the first cam portion and the third swinging portion in contact with the second cam portion at address 40 of the absolute encoder shown in FIG. FIG. 21(b) is an enlarged plan view schematically showing the position of the second swinging portion when the positions of the first swinging portion and the third swinging portion are as shown in FIG. 21(a); be. FIG. 22(a) is an enlarged view schematically showing the positions of the first oscillating portion in contact with the first cam portion and the third oscillating portion in contact with the second cam portion at address 44 of the absolute encoder shown in FIG. FIG. 22(b) is an enlarged plan view schematically showing the position of the second swinging portion when the positions of the first swinging portion and the third swinging portion are as shown in FIG. 22(a); be. FIG. 23(a) is an enlarged view schematically showing the positions of the first swinging portion in contact with the first cam portion and the third swinging portion in contact with the second cam portion at address 48 of the absolute encoder shown in FIG. FIG. 23(b) is an enlarged plan view schematically showing the position of the second oscillating portion when the positions of the first oscillating portion and the third oscillating portion are as shown in FIG. 23(a); be. FIG. 24(a) is an enlarged view schematically showing the positions of the first oscillating portion in contact with the first cam portion and the third oscillating portion in contact with the second cam portion at address 50 of the absolute encoder shown in FIG. FIG. 24(b) is an enlarged plan view schematically showing the position of the second oscillating portion when the positions of the first oscillating portion and the third oscillating portion are as shown in FIG. 24(a); be. FIG. 25(a) is an enlarged view schematically showing the positions of the first oscillating portion in contact with the first cam portion and the third oscillating portion in contact with the second cam portion at address 60 of the absolute encoder shown in FIG. FIG. 25(b) is an enlarged plan view schematically showing the position of the second swinging portion when the positions of the first swinging portion and the third swinging portion are as shown in FIG. 25(a); be. FIG. 26(a) is an enlarged view schematically showing the positions of the first oscillating portion in contact with the first cam portion and the third oscillating portion in contact with the second cam portion at address 80 of the absolute encoder shown in FIG. FIG. 26(b) is an enlarged plan view schematically showing the position of the second swinging portion when the positions of the first swinging portion and the third swinging portion are as shown in FIG. 26(a); be. FIG. 27(a) is an enlarged view schematically showing the positions of the first oscillating portion in contact with the first cam portion and the third oscillating portion in contact with the second cam portion at address 100 of the absolute encoder shown in FIG. FIG. 27(b) is an enlarged plan view schematically showing the position of the second swinging portion when the positions of the first swinging portion and the third swinging portion are as shown in FIG. 27(a); be. FIG. 28(a) is an enlarged view schematically showing the positions of the first oscillating portion in contact with the first cam portion and the third oscillating portion in contact with the second cam portion at address 106 of the absolute encoder shown in FIG. FIG. 28(b) is an enlarged plan view schematically showing the position of the second oscillating portion when the positions of the first oscillating portion and the third oscillating portion are as shown in FIG. 28(a); be. FIG. 29(a) is an enlarged view schematically showing the positions of the first oscillating portion in contact with the first cam portion and the third oscillating portion in contact with the second cam portion at address 110 of the absolute encoder shown in FIG. FIG. 29(b) is an enlarged plan view schematically showing the position of the second swinging portion when the positions of the first swinging portion and the third swinging portion are as shown in FIG. 29(a); be. FIG. 30(a) shows the positions of the first oscillating portion in contact with the first cam portion and the third oscillating portion in contact with the second cam portion at address 120 (=address 0) of the absolute encoder shown in FIG. FIG. 30(b) is an enlarged plan view schematically showing the position of the second oscillating portion when the positions of the first oscillating portion and the third oscillating portion are shown in FIG. 30(a); It is an enlarged plan view showing. 2 is a block diagram schematically showing the functional configuration of the absolute encoder shown in FIG. 1; FIG. 2 is a timing chart showing the relationship between the rotation speed (=address) of the main shaft of the motor and the detection result of the Hall detector Sr in the configuration of the absolute encoder shown in FIG. 1; FIG. 5 is a cross-sectional view schematically showing a configuration of a slider member and a switch section of a counting mechanism in a modification of the absolute encoder according to the embodiment of the invention; FIG. 11 is a plan view schematically showing a configuration of a slider member and a switch section of a counting mechanism in a modification of the absolute encoder according to the embodiment of the invention; FIG. 11 is a plan view schematically showing the configuration of a swing cam and a swing member of a counting mechanism in a modification of the absolute encoder according to the embodiment of the invention;

In an absolute encoder, the amount of rotation (hereinafter referred to as the amount of rotation of the main shaft) over a plurality of rotations of the main shaft (hereinafter referred to as a plurality of rotations) is defined as the rotation of a rotating body that rotates at a reduced speed as the main shaft rotates. It was found that it can be specified by obtaining the angle. That is, the amount of rotation of the main shaft can be specified by multiplying the rotation angle of the rotating body by the reduction ratio. Here, the range of the identifiable rotation amount of the main shaft increases in proportion to the speed reduction ratio. For example, if the speed reduction ratio is 100, the amount of rotation for 100 rotations of the main shaft can be specified.

On the other hand, the required resolution of the rotor becomes smaller in proportion to the reduction ratio. For example, if the speed reduction ratio is 100, the resolution required for the rotor per rotation of the spindle is 360°/100=3.6°, and a detection accuracy of ±1.8° is required. On the other hand, when the speed reduction ratio is 60, the resolution required for the rotating body per rotation of the main shaft is 360°/60=6.0°, and a detection accuracy of ±3.0° is required. Based on this knowledge, the inventor devised a configuration of an absolute encoder capable of increasing the identifiable amount of rotation of the main shaft without increasing the required detection accuracy. Specific configurations will be described below based on several embodiments.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on preferred embodiments with reference to the drawings. In each embodiment and modification, the same or equivalent constituent elements and members are denoted by the same reference numerals, and duplication of description will be omitted as appropriate. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. Also, in each drawing, some of the members that are not important for explaining the embodiments are omitted. Also, terms including ordinal numbers such as first, second, etc. are used to describe various components, but these terms are used only for the purpose of distinguishing one component from other components, and the terms The constituent elements are not limited by

FIG. 1 is a perspective view schematically showing the configuration of an absolute encoder 100 according to an embodiment of the invention. FIG. 2 is a perspective view showing the configuration of the absolute encoder 100 shown in FIG. 1 with the case 3 removed. In FIG. 1, the case 3 and substrate 5 of the absolute encoder 100 are transparently shown, and in FIG. 2, the substrate 5 of the absolute encoder 100 is transparently shown.

The following description is based on the XYZ orthogonal coordinate system. The X-axis direction corresponds to the horizontal left-right direction, the Y-axis direction corresponds to the horizontal front-back direction, and the Z-axis direction corresponds to the vertical up-down direction. The Y-axis direction and the Z-axis direction are orthogonal to the X-axis direction. The X-axis direction may be referred to as left or right, the Y-axis direction as front side or rear side, and the Z-axis direction as upper side or lower side. In this drawing, the state viewed from above in the Z-axis direction is referred to as a plan view, the state viewed from the front in the Y-axis direction is referred to as a front view, and the state viewed from the left and right in the X-axis direction is referred to as a side view. Such direction notation does not limit the use posture of the absolute encoder 100, and the absolute encoder 100 can be used in any posture.

The absolute encoder 100 is an absolute type encoder that specifies and outputs the amount of rotation over a plurality of rotations of the main shaft 1a of the motor 1, as described above. In the embodiment of the present invention, the absolute encoder 100 is provided at the upper end of the motor 1 in the Z-axis direction. In the embodiment of the present invention, the absolute encoder 100 has a substantially rectangular shape in plan view, and has a thin oblong rectangular shape in the Z-axis direction, which is the extending direction of the main shaft 1a, in front view and side view. there is That is, the absolute encoder 100 has a rectangular parallelepiped shape that is flat in the Z-axis direction.

The absolute encoder 100 has a hollow rectangular cylindrical case 3 that houses the internal structure. The case 3 includes a plurality of (for example, four) outer wall portions 3a surrounding at least a portion of the main shaft 1a of the motor 1, the main shaft gear 20, and the intermediate gear 22. As shown in FIG. A lid portion 3 b is fixed to the upper end portion of the outer wall portion 3 a of the case 3 . The lid portion 3b is a plate-like member that has a substantially rectangular shape in plan view and is thin in the Z-axis direction.

The motor 1 may be, for example, a stepping motor or a DC brushless motor. As an example, the motor 1 may be applied as a drive source for driving an industrial robot through a reduction mechanism such as a strain wave gearing. A main shaft 1a of the motor 1 protrudes to both sides in the Z-axis direction. The absolute encoder 100 outputs the amount of rotation of the main shaft 1a of the motor 1 as a digital signal.

The motor 1 has a substantially rectangular shape in plan view, and also has a substantially rectangular shape in the Z-axis direction. That is, the motor 1 has a substantially cubic shape. The length of each of the four outer wall portions forming the outer shape of the motor 1 in plan view is 25 mm, that is, the outer shape of the motor 1 is 25 mm square in plan view. Also, the absolute encoder 100 provided on the motor 1 is 25 mm square in accordance with the outer shape of the motor 1 .

In FIGS. 1 and 2, the substrate 5 is provided so as to cover the inside of the absolute encoder 100 together with the case 3 . The board 5 is a plate-like printed wiring board that has a substantially rectangular shape in plan view and is thin in the Z-axis direction. A connector 70 is connected to the substrate 5 and is used to connect the absolute encoder 100 and an external device (not shown).

FIG. 3 is a perspective view schematically showing the configuration of absolute encoder 100 shown in FIG. 2, with substrate 5, control unit 110 and connector 70 removed. FIG. 4 is a perspective view schematically showing the configuration of the absolute encoder 100 shown in FIG. 3 as seen from another angle. FIG. 5 is a perspective view schematically showing the configuration of the absolute encoder 100 shown in FIG. 4 with the motor 1 removed. FIG. 6 is a plan view schematically showing the configuration of absolute encoder 100 shown in FIG.

The absolute encoder 100 is an absolute type encoder that specifies the amount of rotation over multiple rotations of the main shaft 1a of the motor 1 . The absolute encoder 100 includes a main shaft gear 20, a first worm gear portion 20h (first drive gear), an intermediate gear 22, a first worm wheel portion 22d (first driven gear), and a second worm gear portion 22e (second drive gear). driving gear), countershaft gear 24, second worm wheel portion 24b (second driven gear), magnet Mp, angle sensor Sp, magnet Mq, angle sensor Sq, control unit 110, and counting mechanism 30.

A main shaft 1 a of the motor 1 is an output shaft of the motor 1 and an input shaft to which rotation is input to the absolute encoder 100 . The main shaft gear 20 is fixed to the main shaft 1a of the motor 1 and is rotatably supported by a bearing member of the motor 1 integrally with the main shaft 1a. The first worm gear portion 20h is provided on the outer periphery of the main shaft gear 20 so that both central axes substantially coincide with each other so as to rotate in accordance with the rotation of the main shaft 1a of the motor 1 . The first worm wheel portion 22d is provided on the intermediate gear 22, and the first worm wheel portion 22d is provided so as to mesh with the first worm gear portion 20h and rotate as the first worm gear portion 20h rotates. The first worm wheel portion 22d is provided on the outer circumference of the intermediate gear 22 so that both central axes substantially coincide. The axial angle between the first worm wheel portion 22d and the first worm gear portion 20h is set to 90°.

Although there is no particular limitation on the outer diameter of the first worm wheel portion 22d, in the example of this figure, the outer diameter of the first worm wheel portion 22d is set smaller than the outer diameter of the first worm gear portion 20h. Thus, in the absolute encoder 100, the dimension in the Z-axis direction can be kept smaller than when the outer diameter of the first worm wheel portion 22d is large.

The second worm gear portion 22e is provided on the intermediate gear 22 and rotates as the first worm wheel portion 22d rotates. The second worm gear portion 22e is provided on the outer circumference of the intermediate gear 22 so that both central axes thereof substantially coincide. The second worm wheel portion 24b is provided so as to mesh with the second worm gear portion 22e and rotate as the second worm gear portion 22e rotates. The second worm wheel portion 24b is provided on the countershaft gear 24, and is provided on the outer periphery of the countershaft gear 24 so that the central axes of both of them substantially coincide with each other. The axial angle between the second worm wheel portion 24b and the second worm gear portion 22e is set to 90°. The rotation axis of the second worm wheel portion 24b is provided parallel to the rotation axis of the first worm gear portion 20h.

The angle sensor Sq detects the rotation angle of the second worm wheel portion 24 b , that is, the countershaft gear 24 . The magnet Mq is fixed to the upper surface of the countershaft gear 24 so that both central axes thereof are substantially aligned. Two magnetic poles are provided on the upper surface of the magnet Mq in a direction perpendicular to the rotation axis of the sub-shaft gear 24 . The angle sensor Sq is provided so that its lower surface faces the upper surface of the magnet Mq with a gap therebetween in the Z-axis direction.

As an example, the angle sensor Sq is fixed to a substrate 5 supported by a substrate support member (not shown) of the absolute encoder 100, a base 2 described later, or the like. The angle sensor Sq detects the magnetic pole of the magnet Mq, specifies the rotation angle of the magnet Mq according to the magnetic pole, and outputs it to the control unit 110 . The control unit 110 identifies and outputs the amount of rotation of the main shaft 1a from the rotation angle of the counter shaft gear 24 based on the rotation angle acquired from the angle sensor Sq. As an example, the control unit 110 may output the amount of rotation of the main shaft 1a of the motor 1 as a digital signal.

The magnet Mp is fixed to the upper surface of the main shaft gear 20 so that both central axes thereof substantially coincide with each other. Two magnetic poles are provided on the upper surface of the magnet Mp in a direction perpendicular to the rotation axis of the main shaft gear 20 . The angle sensor Sp detects the rotation angle of the main shaft gear 20 . The angle sensor Sp is provided so that its lower surface faces the upper surface of the magnet Mp with a gap therebetween in the Z-axis direction.

As an example, the angle sensor Sp is fixed to the substrate 5 on which the angle sensor Sq is fixed on the same surface as the angle sensor Sq. The angle sensor Sp detects the magnetic pole of the magnet Mp, specifies the rotation angle of the magnet Mp, which is the rotation angle of the main shaft 1a, according to the magnetic pole, and outputs it to the control unit 110 . The control unit 110 identifies the rotation angle of the main shaft 1a from the rotation angle of the main shaft gear 20 based on the rotation angle acquired from the angle sensor Sp. The resolution of the rotation angle of the spindle 1a corresponds to the resolution of the angle sensor Sp.

The absolute encoder 100 configured in this manner specifies the amount of rotation of the main shaft 1a over a plurality of rotations according to the rotation angle detected by the angle sensor Sq, and determines the rotation angle of the main shaft 1a according to the rotation angle detected by the angle sensor Sp. can be specified.

The control unit 110 specifies the rotation amount of the main shaft 1a based on the rotation angles obtained from the angle sensors Sp and Sq and the rotation amount of the subshaft gear 24 obtained from the Hall detector Sr.

The counting mechanism 30 specifies the amount of rotation of the countershaft gear 24 that rotates according to the rotation of the second worm wheel portion 24b. The counting mechanism 30 includes a first spur gear portion 31 (third driving gear), an oscillating cam 33, a second spur gear portion 32 (third driven gear), a first cam portion 33a (described later), and an oscillating gear. It includes a moving member 35 and a detector 40 (described later). The first spur gear portion 31 is provided on the outer circumference of the countershaft gear 24 so that the center axes of both the second worm wheel portion 24b and the second worm wheel portion 24b are substantially aligned. The first spur gear portion 31 rotates together with the rotation of the second worm wheel portion 24b.

The second spur gear portion 32 is provided so as to mesh with the first spur gear portion 31 and rotate as the first spur gear portion 31 rotates. The second spur gear portion 32 is provided on the outer circumference of the rocking cam 33 so that both central axes thereof substantially coincide. The rotation axis of the second spur gear portion 32 is provided parallel to the rotation axis of the first worm gear portion 20 h and the rotation axis of the first spur gear portion 31 . The first cam portion 33a rotates as the second spur gear portion 32 rotates. The first cam portion 33a is provided so that both central axes of the swing cam 33 substantially coincide with each other. That is, the rotation axes of the first cam portion 33a and the second spur gear portion 32 are provided so as to substantially match the rotation axis of the rocking cam 33. As shown in FIG.

The swinging member 35 swings between the first position and the second position according to the rotation of the first cam portion 33a. The swing member 35 is a substantially scissors-shaped member. The swinging member 35 includes a first swinging portion 36 and a second swinging portion 37 . The first swinging portion 36 is slidable with the first cam portion 33a, and swings according to the sliding movement with the first cam portion 33a. The second swinging portion 37 is formed integrally with the first swinging portion 36 at a left end 37a which is one end, and is integrally formed with the first swinging portion 36 at a right end 37b which is the other end. It has a magnet Mr (described later) that swings between a first position L1 (described later) and a second position L2 (described later) according to the swing of the magnet.

The detector 40 detects whether the swing member 35 is at the first position L1 or the second position L2. The detection unit 40 is a Hall detector Sr that detects whether the magnet Mr is at the first position L1 or the second position L2. As an example, the Hall detector Sr is fixed to the bottom 2b of the base 2 of the absolute encoder 100. As shown in FIG. Hall detector Sr detects whether magnet Mr is at first position L<b>1 or second position L<b>2 according to the position of magnet Mr, and outputs the result to control unit 110 . Note that other magnetic sensors may be used instead of the Hall detector Sr.

The magnet Mr is fixed to the right end 37b of the second swinging portion 37 so that the position SrC of the detection element of the Hall detector Sr and the center axis MrC of the magnet Mr substantially coincide at the first position L1. Further, in the second position L2 of the magnet Mr, the central axis MrC of the magnet Mr is shifted rearward from the position SrC of the detection element of the Hall detector Sr.

The Hall detector Sr detects the magnetic flux from the magnet Mr when the magnet Mr is positioned at the first position L1, and detects the magnetic flux from the magnet Mr when the magnet Mr is positioned at the second position L2. is not detected. The Hall detector Sr is provided such that when the magnet Mr is positioned at the first position L1, its upper surface faces the lower surface of the magnet Mr with a gap therebetween in the Z-axis direction. The central axis MrC and the position SrC of the detection element of the Hall detector Sr are located on the same straight line parallel to the Z-axis.

The number of threads of the first worm gear portion 20h constituting the main shaft gear 20 provided on the main shaft 1a is three, and the number of teeth of the first worm wheel portion 22d is eighteen. That is, the first worm gear portion 20h and the first worm wheel portion 22d constitute the first transmission mechanism 11 with a reduction ratio of 18/3=6. When the first worm gear portion 20h rotates six times, the first worm wheel portion 22d rotates once. The first worm wheel portion 22d and the second worm gear portion 22e are provided coaxially to form the intermediate gear 22, and rotate together. When 1a and main shaft gear 20 rotate six times, intermediate gear 22 rotates once.

The number of threads of the second worm gear portion 22e is two, and the number of teeth of the second worm wheel portion 24b is twenty. That is, the second worm gear portion 22e and the second worm wheel portion 24b constitute the second transmission mechanism 15 with a reduction ratio of 20/2=10. When the second worm gear portion 22e rotates ten times, the second worm wheel portion 24b rotates once. Since the second worm wheel portion 24b rotates integrally with the sub-shaft gear 24, the magnet holder 25, and the magnet Mq, the magnet Mq is 1 when the second worm gear portion 22e that constitutes the intermediate gear 22 rotates 10 times. Rotate. As described above, when the main shaft 1a rotates 60 times, the intermediate gear 22 rotates 10 times, and the counter shaft gear 24 and the magnet Mq rotate once. That is, the angle sensor Sq can specify the amount of rotation for 60 rotations of the main shaft 1a.

The first spur gear portion 31 provided coaxially with the second worm wheel portion 24b has 17 teeth, and the second spur gear portion 32 has 34 teeth. That is, the first spur gear portion 31 and the second spur gear portion 32 constitute the third transmission mechanism 17 having a reduction ratio of 34/17=2. When the first spur gear portion 31 makes two rotations, the second spur gear portion 32 makes one rotation. The second spur gear portion 32 and the first cam portion 33a are provided coaxially to form a rocking cam 33, and rotate together. Rotate the portion 33a. When the first cam portion 33a rotates once, the swinging member 35 swings once, that is, the swinging member 35 reciprocates once. Therefore, the magnet Mr provided at the right end 27b of the second swinging portion 37 of the swinging member 35 rotates the second spur gear portion 32 (first cam portion 33a) when the first spur gear portion 31 makes one rotation. It makes a half turn and moves from the first position L1 to the second position L2. After that, when the first spur gear portion 31 rotates once more, the second spur gear portion 32 (first cam portion 33a) rotates halfway, and the magnet Mr returns to the first position L1. That is, when the first spur gear portion 31 rotates once, the magnet Mr moves away from the Hall detector Sr. Move toward Sr.

Due to the action of these counting mechanisms 30, when the auxiliary shaft gear 24 rotates once, the rocking cam 33 rotates halfway, and the magnet Mr moves from the first position L1 to the second position L2. After that, when the countershaft gear 24 rotates one more time, the magnet Mr returns from the second position L2 to the first position L1. That is, the Hall detector Sr can identify whether the counter shaft gear 24 is in the first rotation or the second rotation based on the timing chart of FIG. 32, which will be described later. When the magnet Mr is at the first position L1, the countershaft gear 24 is in the first rotation, and when the magnet Mr is in the second position L2, the countershaft gear 24 is in the second rotation. Then, the control unit 110 can specify the rotation amount of the main shaft 1a based on the rotation angle obtained from the angle sensor Sq and the rotation amount of the sub shaft gear 24 obtained from the Hall detector Sr. Therefore, the absolute encoder 100 can specify the amount of rotation of the main shaft 1a by the action of these counting mechanisms 30. FIG.

The absolute encoder 100 according to the embodiment of the present invention configured in this way can be a small absolute encoder 100 in which only the angle sensor Sq of the counter shaft gear 24 can be arranged in addition to the angle sensor Sr of the main shaft 1a. , the counter mechanism 30 can double the amount of rotation of the main shaft 1a that can be detected. Therefore, in the absolute encoder 100, even if the absolute encoder 100 is miniaturized, it is possible to further widen the detectable rotation amount range of the main shaft 1a.

Since the Hall detector Sr of the counting mechanism 30 does not detect the rotation angle like the angle sensors Sp and Sq, it is relatively less affected by magnetism from other magnets. In addition, since the absolute encoder 100 increases the detectable amount of rotation of the main shaft 1a by the action of the counting mechanism 30, it is possible to detect the main shaft 1a per one angle sensor without increasing the number of angle sensors. There is no increase in the amount of rotation, and there is no need to increase the speed reduction ratio of each rotating body and each gear by the counting mechanism 30. Therefore, it is possible to comprehensively detect the main shaft 1a without increasing the required detection accuracy. You can increase the amount of rotation.

The configuration of the absolute encoder 100 will be specifically described below.

As shown in FIGS. 1-6, the absolute encoder 100 includes a base 2, a case 3, and a substrate 5. FIG. The base 2 is a base that rotatably supports each rotor, each gear, and each member. The base 2 includes a bottom portion 2b and a plurality (eg, two) of pillars 2c. Supports 2 c provided on the base 2 support the substrate 5 . The board 5 mainly has the angle sensors Sp, Sq and the controller 110 .

The bottom portion 2b is a plate-like portion facing the motor 1 side of the absolute encoder 100 and extends in the X-axis direction and the Y-axis direction. The support 2c is a substantially cylindrical portion that protrudes from the bottom 2b in the Z-axis direction in a direction away from the motor 1. As shown in FIG. A hollow rectangular tubular case 3 is fixed to the bottom portion 2b of the base 2 by a plurality of fixtures (not shown). The fasteners may be screws, for example. A substrate 5 is fixed to the protruding end of the column 2c using, for example, screws (not shown).

The absolute encoder 100 also includes a main shaft gear 20, a first worm gear portion 20h, an intermediate gear 22, a first worm wheel portion 22d, a second worm gear portion 22e, a counter shaft gear 24, and a second worm wheel portion. 24b, magnets Mp and Mq, angle sensors Sp and Sq, a control unit 110, and a counting mechanism 30.

Next, each of the plurality of components included in the absolute encoder 100 will be specifically described.

(main shaft gear)
FIG. 7 is a cross-sectional view schematically showing a state in which a plane passing through the center of the main shaft gear 20 and perpendicular to the intermediate gear 22 is cut in the configuration of the absolute encoder shown in FIG. be. FIG. 8 is an exploded perspective view schematically showing an exploded state of the magnet Mp, the main shaft gear 20 and the main shaft 1a of the motor 1 in the configuration of the absolute encoder 100 shown in FIG.

As shown in FIG. 7, the main shaft gear 20 is a cylindrical member provided coaxially with the main shaft 1a of the motor 1. As shown in FIG. The main shaft gear 20 includes a tubular first tubular portion 20a and a tubular second tubular portion 20b provided on the upper side of the first tubular portion 20a in the Z-axis direction coaxially with the first tubular portion 20a. I have.

In addition, the main shaft gear 20 includes a communicating portion 20c that connects the first tubular portion 20a and the second tubular portion 20b provided radially inward of the second tubular portion 20b, and a first worm gear portion 20h provided in the . By forming the communicating portion 20c in this manner, the communicating portion 20c functions as an escape path for air when the main shaft gear 20 is press-fitted onto the main shaft 1a of the motor 1. FIG.

The inner diameter of the communicating portion 20c is smaller than the inner diameter of the first cylindrical portion 20a and the inner diameter of the second cylindrical portion 20b. The space surrounded by the bottom surface 20d, which is the end surface of the communicating portion 20c on the lower side in the Z-axis direction, and the inner peripheral surface of the first cylindrical portion 20a is used to fix the main shaft gear 20 to the end portion of the main shaft 1a of the motor 1. is the press-fit portion 20e. The press-fit portion 20e is a recess that is recessed upward in the Z-axis direction from the axially lower end portion of the first cylindrical portion 20a. The main shaft 1a of the motor 1 is press-fitted into the press-fit portion 20e, and the main shaft gear 20 rotates together with the main shaft 1a of the motor 1. As shown in FIG. The first worm gear portion 20 h is a gear portion of the main shaft gear 20 .

A space surrounded by a bottom surface 20f, which is the upper end surface in the Z-axis direction of the communicating portion 20c, and the inner peripheral surface of the second cylindrical portion 20b is a magnet holding portion 20g for fixing the magnet Mp. The magnet holding portion 20g is a recess that is recessed downward in the Z-axis direction from the upper end in the Z-axis direction of the second tubular portion 20b. A magnet Mp is press-fitted into the magnet holding portion 20g. The magnet Mp press-fitted into the magnet holding portion 20g has its outer peripheral surface in contact with the inner peripheral surface of the second tubular portion 20b and its lower surface in contact with the bottom surface 20f. As a result, the magnet Mp is positioned in the Z-axis direction and in a direction orthogonal to the Z-axis direction. The Z-axis direction of the magnet Mp is the same as the central axis direction of the main shaft 1 a of the motor 1 .

The first worm gear portion 20 h is configured by a tooth portion formed in a spiral shape and meshes with the first worm wheel portion 22 d of the intermediate gear 22 . The first worm wheel portion 22 d is a gear portion of the intermediate gear 22 . The first worm gear portion 20h is made of polyacetal resin, for example. The first worm gear portion 20h is an example of a first drive gear.

As shown in FIG. 8, the magnet Mp is a substantially cylindrical permanent magnet press-fitted inside the magnet holding portion 20g of the main shaft gear 20, and has an upper surface and a lower surface. The upper surface faces the surface of the angle sensor Sq with a certain distance therebetween. The bottom surface is in contact with the bottom surface 20f of the magnet holding portion 20g of the main shaft gear 20, and defines the position of the main shaft gear 20 in the central axis GmC direction (the position in the Z-axis direction).

A central axis MpC of the magnet Mp (an axis representing the center of the magnet Mp or an axis passing through the center of the boundary of the magnetic poles) coincides with the central axis GmC of the main shaft gear 20 and the central axis MoC of the main shaft 1a of the motor 1 . By aligning the central axes in this way, it is possible to detect the rotation angle or rotation amount with higher accuracy.

In the embodiment of the present invention, the two magnetic poles (N/S) of the magnet Mp are formed adjacent to each other within a plane (XY plane) perpendicular to the central axis MpC of the magnet Mp. is desirable. This further improves the detection accuracy of the rotation angle or rotation amount. The magnet Mp is made of a magnetic material such as ferrite, Nd (neodymium)--Fe (iron)--B (boron). The magnet Mp may be, for example, a rubber magnet containing a resin binder, a bond magnet, or the like.

(intermediate gear)
FIG. 9 is a cross-sectional view schematically showing the configuration of the absolute encoder 100 shown in FIG. 3 taken along a plane passing through the center of the intermediate gear 22 and parallel to the XY plane. FIG. 10 is a partial cross-sectional view schematically showing a state cut along a plane passing through the center of the intermediate gear 22 and perpendicular to the XY plane in the configuration of the absolute encoder shown in FIG.

As shown in FIGS. 9 and 10, the intermediate gear 22 is rotatably supported by an intermediate gear shaft 23 above the bottom portion 2b of the base 2 in the Z-axis direction. The intermediate gear shaft 23 is parallel to the XY plane. Further, the intermediate gear shaft 23 is not parallel to each of the X-axis direction and the Y-axis direction in plan view. That is, the intermediate gear shaft 23 is oblique with respect to the directions in which the X-axis direction and the Y-axis direction respectively extend. The fact that the intermediate gear shaft 23 is oblique with respect to the directions in which the X-axis direction and the Y-axis direction extend means that the intermediate gear shaft 23 extends obliquely with respect to the outer peripheral surface of the base 2 . there is

As shown in FIG. 9, the outer peripheral surface of the base 2 includes a right outer peripheral surface 2d and a left outer peripheral surface 2e parallel to the YZ plane, and a rear outer peripheral surface parallel to the XZ plane and adjacent to the right outer peripheral surface 2d and the left outer peripheral surface 2e. It is composed of the surface 2f and the front outer peripheral surface 2g. The right outer peripheral surface 2d is a side surface provided on the right side of the base 2 in the X-axis direction. The left outer peripheral surface 2e is a side surface provided on the left side of the base 2 in the X-axis direction. The rear outer peripheral surface 2f is a side surface provided on the rear side of the base 2 in the Y-axis direction. The front outer peripheral surface 2g is a side surface provided on the front side of the base 2 in the Y-axis direction.

The dimensions of the absolute encoder 100 in a plan view are, for example, matched to the dimensions of the motor 1 of 25 mm square. Therefore, the intermediate gear 22 arranged parallel to the XY plane is provided so as to extend obliquely with respect to the outer peripheral surface of the base 2, so that the dimension of the absolute encoder 100 in the horizontal direction can be reduced. The horizontal direction is equal to the direction orthogonal to the central axis of the main shaft 1a of the motor 1 and equal to the direction parallel to the XY plane.

The intermediate gear 22 has a first worm wheel portion 22d, a second worm gear portion 22e, a right sliding portion 22a, a left sliding portion 22b, and a through hole 22c. The intermediate gear 22 is a cylindrical member through which the intermediate gear shaft 23 is inserted through a through hole 22c extending along the intermediate gear shaft 23 . The through hole 22 c is a space surrounded by the inner peripheral surface of the intermediate gear 22 . The intermediate gear shaft 23 is slidably inserted into the through hole 22c, and the intermediate gear 22 is rotatably supported by the intermediate gear shaft 23. As shown in FIG. The intermediate gear 22 is a member integrally molded of metal, resin, or the like, and is formed of polyacetal resin as an example here.

The first worm wheel portion 22d is a gear with which the first worm gear portion 20h of the main shaft gear 20 meshes. The first worm wheel portion 22 d is an example of a first driven gear and a gear portion of the intermediate gear 22 . The first worm wheel portion 22d is provided at a portion near the center of the bottom portion 2b of the base 2. As shown in FIG. Also, the first worm wheel portion 22 d is composed of a plurality of teeth provided on the outer peripheral portion of the cylindrical portion of the intermediate gear 22 .

The outer diameter of the first worm wheel portion 22d is smaller than the outer diameter of the first worm gear portion 20h. Since the central axis of the first worm wheel portion 22d is parallel to the bottom portion 2b of the base 2, the outer diameter of the first worm wheel portion 22d becomes smaller, so that the absolute encoder 100 moves in the Z-axis direction (height direction). Miniaturization is possible.

The second worm gear portion 22e is configured by a spirally formed tooth portion, and is coaxially adjacent to the first worm wheel portion 22d. Also, the second worm gear portion 22 e is provided on the outer peripheral portion of the cylindrical portion of the intermediate gear 22 . The rotational force of the intermediate gear 22 is transmitted to the sub-shaft gear 24 by the second worm gear portion 22 e meshing with the second worm wheel portion 24 b provided on the sub-shaft gear 24 .

The second worm gear portion 22 e is an example of a second driving gear and also a gear portion of the intermediate gear 22 . The second worm wheel portion 24 b is a gear portion of the countershaft gear 24 . The central axis of the second worm wheel portion 24b and the central axis of the second worm gear portion 22e are perpendicular to the central axis of the second worm wheel 24b and perpendicular to the central axis of the second worm gear portion 22e when viewed from the direction. , are orthogonal to each other.

The outer diameter of the second worm gear portion 22e is set as small as possible in order to make the absolute encoder 100 compact in the Z-axis direction (height direction).

The right sliding portion 22a of the intermediate gear 22 is provided on one end side of the intermediate gear 22, that is, on the right side of the intermediate gear 22 in the X-axis direction. The right sliding portion 22 a of the intermediate gear 22 is in contact with one end 51 a of the leaf spring 51 . The leaf spring 51 is an example of an elastic member, and is made of metal, for example.

One end 51a of the leaf spring 51 is composed of two branched bodies bifurcated from the leaf spring 51 (see FIG. 4, for example). A gap larger than the diameter of the intermediate gear shaft 23 is formed between the two branched bodies forming the one end 51 a of the leaf spring 51 . Therefore, the two branched bodies straddle the intermediate gear shaft 23 so as not to contact the intermediate gear shaft 23 . The other end 51 b of the leaf spring 51 is fixed to the wall portion 52 of the base 2 with a screw 53 .

One end 51a of the leaf spring 51 is provided at a position facing the right sliding portion 22a of the intermediate gear 22 after the intermediate gear 22 is assembled. The right sliding portion 22a of the intermediate gear 22 is pressed against the one end 51a of the leaf spring 51, thereby sliding the intermediate gear shaft 23 along the central axis of the intermediate gear shaft 23 from the right end 23a of the intermediate gear shaft 23 to the intermediate gear shaft 23. is urged in the direction toward the left end 23b. When the intermediate gear 22 rotates in this state, the right sliding portion 22a of the intermediate gear 22 slides in contact with the one end 51a of the leaf spring 51. As shown in FIG.

The left sliding portion 22b of the intermediate gear 22 is provided on the other end side of the intermediate gear 22, that is, on the left side of the intermediate gear 22 in the X-axis direction. The left sliding portion 22 b of the intermediate gear 22 is in contact with the wall portion 54 . Wall portion 54 defines the position of intermediate gear 22 . Since the intermediate gear 22 is urged by the plate spring 51 in the direction from the right end 23a of the intermediate gear shaft 23 toward the left end 23b of the intermediate gear shaft 23, the left sliding portion 22b of the intermediate gear 22 also moves in the same direction. is biased against the wall portion 54 . As a result, the biasing force is transmitted to the wall portion 54 , and the intermediate gear 22 is stably supported in the direction from the right end 23 a of the intermediate gear shaft 23 toward the left end 23 b of the intermediate gear shaft 23 . When the intermediate gear 22 rotates in this state, the left sliding portion 22b of the intermediate gear 22 slides in contact with the wall portion 54. As shown in FIG.

The wall portion 54 and the wall portion 55 are an example of a holding portion that rotatably holds the intermediate gear 22 via the intermediate gear shaft 23 . The wall portion 54 is a substantially rectangular parallelepiped portion that protrudes from the bottom portion 2b of the base 2 in the direction away from the motor 1 in the Z-axis direction so as to form a pair with the wall portion 55 . The wall portion 54 is provided on the left side in the X-axis direction and the rear side in the Y-axis direction in plan view. The wall portion 55 is provided on the right side in the X-axis direction and near the center in the Y-axis direction in a plan view.

The wall portion 54 , the wall portion 55 and the intermediate gear shaft 23 function as a holding portion that holds the intermediate gear 22 rotatably. The intermediate gear shaft 23 is a cylindrical rod-shaped member and has a right end 23a and a left end 23b. A left end 23b of the intermediate gear shaft 23 is press-fitted into a hole formed in a wall portion 54 of the base 2 and fixed by a fixture 54a.

On the other hand, the right end 23a of the intermediate gear shaft 23 may be inserted into a hole formed in the wall portion 55 and positioned by the fixture 55a. It need not be pressed into the hole. By inserting the right end 23a of the intermediate gear shaft 23 into the hole of the wall portion 55 instead of press-fitting it, compared to the case where the right end 23a of the intermediate gear shaft 23 is press-fitted into the hole of the wall portion 55, the Assembly of the intermediate gear shaft 23 is facilitated.

Thus, the intermediate gear 22 comprises a first worm wheel portion 22d and a second worm gear portion 22e, the axis of rotation of the main shaft gear 20 is in a twisted position with respect to the axis of rotation of the intermediate gear 22, and the second 2 It is provided parallel to the rotational axis of the worm wheel portion 24b. According to this configuration, it is possible to specify the amount of rotation over multiple rotations of the main shaft gear 20 according to the detection result of the angle sensor Sq. Since the rotation axis of the intermediate gear 22 is at a twisted position with respect to the rotation axes of the main shaft gear 20 and the counter shaft gear 24 and perpendicular to each other when viewed from the front, the absolute encoder 100 has a curved transmission path and is thinned. can be done.

(Secondary shaft gear)
FIG. 11 is a partial cross-sectional view schematically showing a state cut along a plane passing through the center of the counter shaft gear 24 and orthogonal to the intermediate gear 22 in the configuration of the absolute encoder 100 shown in FIG. FIG. 12 is an exploded perspective view schematically showing an exploded state of magnet Mq, magnet holder 25, countershaft gear 24 and bearing 2i in the configuration of absolute encoder 100 shown in FIG.

As shown in FIG. 11, the sub-shaft gear 24 is a cylindrical member that is press-fitted into and fixed to the shaft portion 25b of the magnet holder 25. As shown in FIG. The countershaft gear 24 includes a second worm wheel portion 24b, a first flat gear portion 31 of the counting mechanism 30, and a through hole 24a. The countershaft gear 24 is a member integrally molded of metal or resin, and is formed of polyacetal resin as an example here.

The second worm wheel portion 24b is a gear with which the second worm gear portion 22e of the intermediate gear 22 meshes. The second worm wheel portion 24b is an example of a second driven gear. The second worm wheel portion 24 b is composed of a plurality of teeth provided on the outer peripheral portion of the upper cylindrical portion of the countershaft gear 24 . As the intermediate gear 22 rotates, the rotational force of the intermediate gear 22 is transmitted to the subshaft gear 24 via the second worm gear portion 22e and the second worm wheel portion 24b of the intermediate gear 22.

The first spur gear portion 31 is configured by a tooth portion formed in a spur tooth shape, and is provided below the second worm wheel portion 24b so as to be coaxially adjacent to the second worm wheel portion 24b. Also, the first spur gear portion 31 is provided on the outer peripheral portion of the lower cylindrical portion of the countershaft gear 24 . The radius of the outer peripheral portion of the lower cylindrical portion of the countershaft gear 24 is smaller than the outer peripheral portion of the upper cylindrical portion of the countershaft gear 24 .

The first spur gear portion 31 meshes with the second spur gear portion 32 of the swing cam 33 , so that the rotational force of the countershaft gear 24 is transmitted to the swing cam 33 . The first spur gear portion 31 is an example of a third drive gear and is a gear portion of the countershaft gear 24 . The second spur gear portion 32 is a gear portion of the swing cam 33 . The central axis of the second spur gear portion 32 and the central axis of the first spur gear portion 31 extend parallel to each other in the Z-axis direction.

The through hole 24 a is a hole that penetrates along the central axis of the cylindrical countershaft gear 24 . The shaft portion 25b of the magnet holder 25 is press-fitted into the through hole 24a, and the sub-shaft gear 24 rotates integrally with the magnet holder 25. As shown in FIG.

The magnet holder 25 has a magnet holding portion 25a and a shaft portion 25b. The magnet holder 25 is a member integrally molded of metal or resin, and is made of non-magnetic stainless steel as an example here. Outer rings of two bearings 2i are press-fitted into the inner peripheral surface of a bearing holder portion 2h formed in the base 2. As shown in FIG. A shaft portion 25b of the magnet holder 25 is a cylindrical member. The shaft portion 25b is press-fitted into the through hole 24a of the countershaft gear 24, and the lower portion of the shaft portion 25b is inserted into the inner rings of the two bearings 2i. Therefore, the magnet holder 25 is pivotally supported with respect to the base 2 by the two bearings 2 i and rotates together with the counter shaft gear 24 .

A magnet holder 25 a is provided at the upper end of the magnet holder 25 . The magnet holding portion 25a is a bottomed cylindrical member. The magnet holding portion 25 a has a recess that is recessed downward from the upper end surface of the magnet holder 25 . The outer peripheral surface of the magnet Mq is in contact with the inner peripheral surface of the magnet holding portion 25a. Thereby, the magnet Mq is fixed to the magnet holding portion 25a.

Since the shaft portion 25b of the magnet holder 25 is pivotally supported by two bearings 2i arranged in the bearing holder portion 2h formed in the base 2, the inclination of the magnet holder 25 can be prevented. If the two bearings 2i are arranged as far apart as possible in the Z-axis direction of the shaft portion 25b, the effect of preventing the magnet holder 6 from tilting becomes greater.

As shown in FIG. 12, the magnet Mq is a substantially cylindrical permanent magnet that is press-fitted inside the magnet holding portion 25a of the magnet holder 25, and has an upper surface and a lower surface. The upper surface of the magnet Mq faces the lower surface of the angle sensor Sp with a certain distance therebetween. The central axis MqC of the magnet Mq (the axis representing the center of the magnet Mq or the axis passing through the center of the boundary of the magnetic poles) is the central axis SC of the magnet holder 25, the central axis GsC of the sub-shaft gear 24, and the central axis BC of the bearing 2i. Match. By aligning the central axes in this way, it is possible to detect the rotation angle or rotation amount with higher accuracy.

In the embodiment of the present invention, the two magnetic poles (N/S) of the magnet Mq are formed adjacent to each other in a plane (XY plane) perpendicular to the central axis MqC of the magnet Mq. is desirable. This further improves the detection accuracy of the rotation angle or rotation amount. The magnet Mq is made of a magnetic material such as ferrite, Nd (neodymium)--Fe (iron)--B (boron). The magnet Mq may be, for example, a rubber magnet containing a resin binder, a bond magnet, or the like.

(Swing cam)
FIG. 13 is a cross-sectional view schematically showing a state of the configuration of the absolute encoder 100 shown in FIG. FIG. 14 is an exploded perspective view schematically showing a disassembled state of the swing cam shaft 34 and the swing cam 33 in the configuration of the absolute encoder 100 shown in FIG.

As shown in FIGS. 13 and 14, the rocking cam 33 is a cylindrical member that is pivotally supported by the rocking cam shaft 34 and rotates. The swing cam 33 includes a second spur gear portion 32, a first cam portion 33a, a second cam portion 33b, and a through hole 33c. The rocking cam 33 is a member integrally molded of metal or resin, and is made of polyacetal resin as an example here.

The second spur gear portion 32 is a gear with which the first spur gear portion 31 of the countershaft gear 24 meshes. The second spur gear portion 32 is an example of a third driven gear. The second spur gear portion 32 is composed of a plurality of spur teeth provided on the outer peripheral portion of the lower cylindrical portion of the swing cam 33 . As the countershaft gear 24 rotates, the rotational force of the countershaft gear 24 is transmitted to the swing cam 33 via the first spur gear portion 31 and the second spur gear portion 32 of the countershaft gear 24 .

The first cam portion 33a rotates as the second spur gear portion 32 rotates. The first cam portion 33 a is configured by a substantially fan-shaped portion, and is provided above the second spur gear portion 32 so as to be coaxially adjacent to the second spur gear portion 32 . Further, the first cam portion 33a of the rocking cam 33 has a sliding surface 33d on the outer peripheral portion of the first cam portion 33a. The radius of the outer peripheral portion of the fan-shaped portion of the first cam portion 33 a is smaller than the outer peripheral portion of the cylindrical portion of the second spur gear portion 32 . The rotational force of the swing cam 33 is transmitted to the first swing portion 36 of the swing member 35 by the first cam portion 33 a sliding against the first swing portion 36 of the swing member 35 .

The second cam portion 33b rotates as the second spur gear portion 32 rotates. The second cam portion 33b is composed of a substantially fan-shaped portion having a shape different from that of the first cam portion 33a, and is provided above the first cam portion 33a and coaxially adjacent to the first cam portion 33a. . Further, the second cam portion 33b of the swing cam 33 has a sliding surface 33e on the outer peripheral portion of the second cam portion 33b. The radius of the outer peripheral portion of the fan-shaped portion of the second cam portion 33b is smaller than the radius of the outer peripheral portion of the fan-shaped portion of the first cam portion 33a. The rotation force of the swing cam 33 is transmitted to the third swing portion 38 of the swing member 35 by sliding the second cam portion 33 b on the third swing portion 38 of the swing member 35 .

The through hole 33c is a cylindrical hole penetrating along the central axis of the swing cam 33 . A rocking cam shaft 34 is inserted into the through hole 33c. The rocking camshaft 34 is a cylindrical bar-shaped member made of metal or resin, and is made of non-magnetic stainless steel as an example here. A lower end 34a of the rocking cam shaft 34 is press-fitted and fixed to the inner peripheral surface of the rocking cam shaft holder portion 2j formed in the base 2. As shown in FIG. The rocking cam 33 is restricted at the upper end 34b of the rocking cam shaft 34 by a fixture 34c so as not to move in the Z-axis direction. Therefore, the swing cam shaft 34 is pivotally supported with respect to the base 2 by the swing cam shaft holder portion 2 j , and the swing cam 33 rotates around the central axis of the swing cam shaft 34 .

(Swing member)
FIG. 13 is a cross-sectional view schematically showing a state of the configuration of the absolute encoder 100 shown in FIG. FIG. 15 is a cross-sectional view schematically showing the configuration of the absolute encoder 100 shown in FIG. 1 taken along a plane passing through the center of the swing member shaft 42 and the magnet Mr with the motor 1 removed.

FIG. 16 is an enlarged plan view schematically showing the configuration of rocking cam 33 and rocking member 35 of absolute encoder 100 shown in FIG. FIG. 17 shows the configuration of the absolute encoder 100 shown in FIG. 4 is an exploded perspective view schematically showing an exploded state of the screw holder 41. FIG.

As shown in FIGS. 13 and 15 to 17, the swinging member 35 is a substantially scissor-shaped member that is inserted into the swinging member shaft 42 and swings. The swinging member 35 includes a first swinging portion 36, a second swinging portion 37, a third swinging portion 38, an elastic member 39, and a magnet Mr. The first swinging portion 36 is slidable with the first cam portion 33a, and swings according to the sliding movement with the first cam portion 33a.

The second swinging portion 37 extends to the first swinging portion 36 at the left end 37a, and moves between the first position L1 and the second position L2 at the right end 37b as the first swinging portion 36 swings. It has a magnet Mr that oscillates between The third swinging portion 38 extends so as to sandwich the first cam portion 33a and the second cam portion 33b with the first swinging portion 36 in plan view, and is slidable with the second cam portion 33b. , and swings as it slides with the second cam portion 33b. The elastic member 39 attracts the first swinging portion 36 and the third swinging portion 38 to each other.

Specifically, the first rocking portion 36 is a substantially rectangular rod-like member on which the first cam portion 33a of the rocking cam 33 slides. The first swinging portion 36 obliquely extends in the front-rear direction. At the rear end 36a of the first swinging portion 36, a sliding surface 36b on which the sliding surface 33d of the first cam portion 33a slides is provided on the right side surface of the first swinging portion 36 in the X-axis direction. It is Further, at the rear end 36a of the first swinging portion 36, an elastic member 39 for attaching an elastic member 39, which is a substantially cylindrical portion protruding upward in the Z-axis direction from the upper surface of the first swinging portion 36 A member mounting portion 36c is provided.

A second swinging portion 37 extends rightward in the X-axis direction from a front end 36d of the first swinging portion 36 . The first swinging portion 36 is integrally molded with metal or resin at the front end 36d of the first swinging portion 36 and the left end 37a of the second swinging portion 37 to form a substantially L-shaped member. there is The first swinging portion 36 and the second swinging portion 37 are made of polyacetal resin as an example here. The second swinging portion 37 is a substantially rectangular rod-shaped member that swings in the front-rear direction in accordance with the left-right swinging motion of the first swinging portion 36 .

At the right end 37b of the second swinging portion 37, a magnet screw holder 41 having a magnet Mr on the lower side in the Z-axis direction and a screw portion on the outer peripheral surface, and a cylindrical hole penetrating along the Z-axis direction. , and a screw hole 37c having a screw groove portion to be screwed with the magnet screw holder 41 is provided on the inner peripheral surface. The magnet screw holder 41 is screwed into the screw hole 37c.

Therefore, when the magnet screw holder 41 is rotated, the magnet screw holder 41 is screwed into the screw hole 37c, and the magnet screw holder 41 moves in the Z-axis direction. By moving the magnet Mr in the Z-axis direction, the distance between the magnet Mr and the Hall detector Sr can be adjusted, and the strength of the magnetic flux applied to the Hall detector Sr can be changed. Thereby, the threshold for the Hall detector Sr to detect the magnet Mr can be adjusted.

A through-hole 37d, which is a cylindrical hole that penetrates along the Z-axis direction, is formed in the left end 37a of the second swinging portion 37. As shown in FIG. The swing member shaft 42 is inserted into the through hole 37d.

The magnet Mr is a substantially columnar permanent magnet that is press-fitted into a depression on the lower side of the magnet screw holder 41, and has an upper surface and a lower surface. The lower surface of the magnet Mr faces the upper surface of the Hall detector Sr, which will be described later, with a certain distance therebetween. The central axis MrC of the magnet Mr (the axis representing the center of the magnet Mr) coincides with the central axis MsC of the magnet screw holder 41, the central axis ShC of the screw hole 37c, and the central axis SrC of the Hall detector Sr. By aligning the central axes in this way, it is possible to detect the rotation angle or rotation amount with higher accuracy.

In the embodiment of the present invention, the magnet Mr is made of a magnetic material such as ferrite, Nd (neodymium)--Fe (iron)--B (boron). The magnet Mr may be, for example, a rubber magnet containing a resin binder, a bond magnet, or the like. Since detection of the magnet Mr by the Hall detector Sr requires less detection accuracy than detection of the magnets Mp and Mq by the angle sensors Sp and Sq, a compact magnet with a low magnetic flux density can be used. Therefore, it is possible to increase the detectable amount of rotation of the main shaft 1a of the motor 1 while suppressing the influence of magnetic interference and the like.

The third rocking portion 38 is a substantially rectangular curved rod-like member on which the second cam portion 33b of the rocking cam 33 slides. The third swing portion 38 obliquely extends in the front-rear direction. At the rear end 38a of the third swinging portion 38, a sliding surface 38b on which the sliding surface 33e of the second cam portion 33b slides is provided on the left side surface of the third swinging portion 38 in the X axis direction. It is

In addition, at the central portion of the third swinging portion 38 in the front-rear direction, an elastic member 39, which is a substantially cylindrical portion projecting upward in the Z-axis direction from the upper surface of the third swinging portion 38, is attached. An elastic member mounting portion 38c is provided. A through-hole 38e, which is a cylindrical hole that penetrates along the Z-axis direction, is formed in a front end 38d of the third swinging portion 38. As shown in FIG. The through hole 38 e is inserted into the swing member shaft 42 above the first swing portion 36 and the second swing portion 37 .

The rocking member shaft 42 is a cylindrical rod-shaped member made of metal or resin, and is made of non-magnetic stainless steel as an example here. A lower end 42a of the swing member shaft 42 is press-fitted and fixed to the inner peripheral surface of the swing member shaft holder portion 2k formed in the base 2. As shown in FIG. The first swinging portion 36, the second swinging portion 37, and the third swinging portion 38 are restricted at the upper end 42b of the swinging member shaft 42 so as not to move in the Z-axis direction by the fixture 42c. Therefore, the swinging member shaft 42 is pivotally supported with respect to the base 2 by the swinging member shaft holder portion 2k, and the first swinging portion 36, the second swinging portion 37 and the third swinging portion 38 swing. It swings around the central axis of the member shaft 42 .

The elastic member 39 is arranged between the first swinging portion 36 and the third swinging portion 38 in the left-right direction. The elastic member 39 is, for example, a tension spring. , and pulls the elastic member mounting portion 36c and the elastic member mounting portion 38c toward each other in the left-right direction.

As a result, the first swinging portion 36 and the third swinging portion 38 are biased toward each other in the left-right direction. As a result, the followability of the first oscillating portion 36 is improved, and highly accurate movement of the oscillating member 35 becomes possible. In particular, even when the swing cam 33 rotates at high speed, the followability of the swing member 35 can be ensured. The length of the elastic member 39 arranged between the first swinging portion 36 and the third swinging portion 38 is always constant, and the biasing force of the elastic member 39 is also always constant. .

FIG. 18 is a plan view schematically showing the configuration of absolute encoder 100 shown in FIG. 6 with swing member 35 removed. The detector 40 detects whether the swing member 35 is at the first position L1 or the second position L2. The detection unit 40 is a Hall detector Sr that detects whether the magnet Mr is at the first position L1 or the second position L2.

Specifically, the Hall detector Sr is fixed to the bottom 2b of the base 2 of the absolute encoder 100 while being mounted on a substrate. The Hall detector Sr is arranged on the right side in the X-axis direction and on the front side in the Y-axis direction, and faces the lower surface of the magnet Mr with a certain distance therebetween. The central axis SrC of the Hall detector Sr is shifted forward from the center of the Hall detector Sr. The central axis SrC of the Hall detector Sr coincides with the central axis MrC of the magnet Mr at the first position L1. The Hall detector Sr detects the magnet Mr when the magnet Mr is positioned at the first position L1, and does not detect the magnet Mr when the magnet Mr is positioned at the second position L2.

Next, operations of the swing cam 33 and the swing member 35 of the absolute encoder 100 will be specifically described.

19(a) to 30(a) show the first swinging portion 36 in contact with the first cam portion 33a and the third swinging portion 36 in contact with the second cam portion 33b at addresses 0 to 120 of the absolute encoder shown in FIG. 4 is an enlarged plan view schematically showing the position of a swinging part 38; FIG. For example, address 0 is the 0th rotation of the main shaft, and the central axis SrC of the Hall detector Sr and the central axis MrC of the magnet Mr are aligned. For example, address 50 is the 50th rotation of the main shaft. Yes, the signal from the Hall detector Sr is inverted at address 50 as a boundary. 19(b) to 30(b) show the position of the second oscillating portion 37 when the positions of the first oscillating portion 36 and the third oscillating portion 38 are as shown in FIGS. 19(a) to 30(a). is an enlarged plan view schematically showing the. 19 to 30, the elastic member 39 is removed in order to confirm the operation of the swing cam 33 and the swing member 35. As shown in FIG. 19 to 30, in order to confirm the operation of the magnet Mr, the magnet Mr is removed and only the central axis MrC of the magnet Mr is shown.

As described above, in the absolute encoder 100, when the main shaft 1a rotates 60 times, the intermediate gear 22 rotates 10 times and the countershaft gear 24 rotates once. Also, in the absolute encoder 100, when the auxiliary shaft gear 24 rotates twice, the rocking cam 33 rotates once, the rocking member 35 reciprocates once, and the magnet Mr moves from the first position L1 to the second position L2. It moves and then returns from the second position L2 to the first position L1. Therefore, the absolute encoder 100 can specify the rotation amount for 120 rotations of the main shaft 1a, and can indicate the positions of the gears and the swing member 35 in these rotation amounts as 0 to 120 addresses.

FIG. 19 shows the positions of the first oscillating portion 36 in contact with the first cam portion 33a at address 0 of the absolute encoder 100, and the oscillating gear 33 and oscillating member 35 in contact with the second cam portion 33b. , the positions of the rocking cam 33 and the rocking member 35 when the main shaft 1a rotates zero. 19 shows the reference positions of the swing cam 33 and the swing member 35. FIG. At this time, as shown in FIG. 19(b), the central axis MrC of the magnet Mr and the central axis SrC of the Hall detector Sr substantially coincide at the first position L1.

As shown in FIGS. 20(a) to 21(a), when the swing cam 33 moves from address 0 to addresses 25 and 40, the swing cam 33 rotates clockwise. At this time, the sliding surface 33e of the second cam portion 33b of the swing cam 33 slides on the sliding surface 38b of the third swing portion 38 of the swing member 35, and the first cam portion of the swing cam 33 slides. 33 a slides on the sliding surface 36 b of the first swing portion 36 of the swing member 35 . Here, the positions of the first swinging portion 36 and the third swinging portion 38 of the swinging member 35 remain unchanged, and the position of the second swinging portion 37 of the swinging member 35 remains unchanged. Therefore, in FIGS. 20(b) to 21(b), the center axis MrC of the magnet Mr and the center axis SrC of the Hall detector Sr remain substantially aligned at the first position L1.

As shown in FIGS. 22(a) to 24(a), when the swing cam 33 moves from address 40 to addresses 44, 48, and 50, the swing cam 33 rotates further clockwise. At this time, the sliding surface 36b of the first oscillating portion 36 of the oscillating member 35 presses the first cam portion 33a of the oscillating cam 33, and the first oscillating portion 36 of the oscillating member 35 moves toward the oscillating member shaft. 42 to rotate counterclockwise. When the first swinging portion 36 rotates counterclockwise about the swinging member shaft 42 , the biasing force of the elastic member 39 causes the third swinging portion 38 of the swinging member 35 to rotate counterclockwise about the swinging member shaft 42 . As it rotates, the sliding surface 38b of the third swinging portion 38 presses the second cam portion 33b of the swinging cam 33 . Further, when the first swinging portion 36 rotates counterclockwise about the swinging member shaft 42 , the second swinging portion 37 rotates counterclockwise about the swinging member shaft 42 . Therefore, in FIGS. 22(b) to 24(b), the center axis MrC of the magnet Mr moves rearward from the first position L1 toward the second position L2.

As shown in FIG. 25(a), when the swing cam 33 moves from address 50 to address 60, the swing cam 33 rotates further clockwise. At this time, the sliding surface 36b of the first swinging portion 36 of the swinging member 35 further presses the first cam portion 33a of the swinging cam 33, and the first swinging portion 36 of the swinging member 35 It further rotates counterclockwise around the shaft 42 . When the first swinging portion 36 rotates further counterclockwise about the swinging member shaft 42 , the biasing force of the elastic member 39 causes the third swinging portion 38 of the swinging member 35 to further rotate leftward about the swinging member shaft 42 . As it rotates, the sliding surface 38b of the third swinging portion 38 presses the second cam portion 33b of the swinging cam 33 further. Further, when the first swinging portion 36 rotates further counterclockwise about the swinging member shaft 42 , the second swinging portion 37 further rotates counterclockwise about the swinging member shaft 42 . Therefore, in FIG. 25(b), the central axis MrC of the magnet Mr moves to the second position L2.

As shown in FIGS. 26(a) to 27(a), when the swing cam 33 moves from address 60 to address 80 and then to address 100, the swing cam 33 rotates further clockwise. At this time, the sliding surface 33d of the first cam portion 33a of the swing cam 33 slides on the sliding surface 36b of the first swing portion 36 of the swing member 35, and the second cam portion of the swing cam 33 slides. 33 b slides on the sliding surface 38 b of the third swing portion 38 of the swing member 35 . Here, the positions of the first swinging portion 36 and the third swinging portion 38 of the swinging member 35 remain unchanged, and the position of the second swinging portion 37 of the swinging member 35 remains unchanged. Therefore, in FIGS. 26(b) to 27(b), the central axis MrC of the magnet Mr remains at the second position L2.

As shown in FIGS. 28A to 29A, when the swing cam 33 moves from address 100 to addresses 106 and 110, the swing cam 33 rotates further clockwise. At this time, the sliding surface 38b of the third swinging portion 38 of the swinging member 35 presses the second cam portion 33b of the swinging cam 33, and the third swinging portion 38 of the swinging member 35 moves toward the swing member shaft. 42 to rotate clockwise. When the third swinging portion 38 rotates clockwise about the swinging member shaft 42 , the biasing force of the elastic member 39 causes the first swinging portion 36 of the swinging member 35 to rotate clockwise about the swinging member shaft 42 . As the swing member 35 rotates, the sliding surface 36 b of the first swing portion 36 of the swing member 35 presses the first cam portion 33 a of the swing cam 33 . When the first swinging portion 36 rotates clockwise about the swinging member shaft 42 , the second swinging portion 37 rotates clockwise about the swinging member shaft 42 . Therefore, in FIGS. 28(b) and 29(b), the central axis MrC of the magnet Mr moves forward from the second position L2 toward the first position L1.

As shown in FIG. 30(a), when the swing cam 33 moves from address 110 to address 120, the swing cam 33 rotates further clockwise and returns to address 0. As shown in FIG. At this time, the sliding surface 38b of the third oscillating portion 38 of the oscillating member 35 further presses the second cam portion 33b of the oscillating cam 33, and the third oscillating portion 38 of the oscillating member 35 moves toward the oscillating member. It rotates further clockwise around the shaft 42 . When the third swinging portion 38 further rotates clockwise around the swinging member shaft 42 , the biasing force of the elastic member 39 causes the first swinging portion 36 of the swinging member 35 to further rotate rightward around the swinging member shaft 42 . The sliding surface 36b of the first swinging portion 36 of the swinging member 35 presses the first cam portion 33a of the swinging cam 33 further. When the first swinging portion 36 further rotates clockwise about the swinging member shaft 42 , the second swinging portion 37 further rotates clockwise about the swinging member shaft 42 . Therefore, in FIG. 30(b), the central axis MrC of the magnet Mr moves to the first position L1, and the central axis MrC of the magnet Mr and the central axis SrC of the Hall detector Sr are substantially aligned at the first position L1. Match.

In the embodiment of the present invention, the rocking cam 33 may rotate counterclockwise, and even when the rocking cam 33 rotates counterclockwise, the rocking member 35 is rocked in the same manner as described above. The central axis MrC of the magnet Mr can be moved by rotating around the member axis 42 .

Next, the configuration of the control section 110 of the absolute encoder 100 will be specifically described.

(control part)
FIG. 31 is a block diagram schematically showing a functional configuration of absolute encoder 100 shown in FIG. 1. Referring to FIG. Each block of the control unit 110 shown in FIG. 31 can be implemented by hardware such as a CPU (central processing unit) of a computer or other device or mechanical device, and can be implemented by a computer program or the like in terms of software. However, here, the functional blocks realized by their cooperation are drawn. Therefore, those skilled in the art who have read this specification will understand that these functional blocks can be realized in various forms by combining hardware and software.

The control unit 110 includes a rotation angle acquisition unit 111 , a rotation angle acquisition unit 112 , a magnet presence/absence detection unit 113 , a table processing unit 114 , a rotation amount identification unit 115 and an output unit 116 . The rotation angle acquisition unit 111 acquires the rotation angle Ap of the main shaft gear 20 based on the signal output from the angle sensor Sp. The rotation angle Ap is angle information indicating the rotation angle of the main shaft gear 20 .

The rotation angle acquisition unit 112 acquires the rotation angle Aq of the sub shaft gear 24 based on the signal output from the angle sensor Sq. The rotation angle Aq is angle information indicating the rotation angle of the subshaft gear 24 . The magnet presence/absence detector 113 acquires the detection information Ar of the magnet Mr based on the signal output from the Hall detector Sr. The detection information Ar is information as to whether or not the magnet Mr is detected.

The table processing unit 114 refers to the correspondence table 114a that stores the rotation angle Aq, the detection information Ar, and the number of rotations of the main shaft gear 20 corresponding to the rotation angle Aq and the detection information Ar. and the rotational speed of the main shaft gear 20 corresponding to the detection information Ar. The rotation amount specifying unit 115 specifies the rotation amount of the main shaft gear 20 over multiple rotations according to the number of rotations of the main shaft gear 20 specified by the table processing unit 114 and the acquired rotation angle Aq and detection information Ar. The output unit 116 converts the specified amount of rotation of the main shaft gear 20 over a plurality of rotations into information indicating the amount of rotation and outputs the information.

FIG. 32 is a timing chart showing the relationship between the rotation speed (address) of the main shaft 1a of the motor 1 and the detection result of the Hall detector Sr in the configuration of the absolute encoder 100 shown in FIG. For the sake of convenience, this timing chart schematically shows changes in the voltage output from the magnet presence/absence detector 113 when the sub shaft gear 24 rotates two times, that is, when the main shaft 1a rotates 120 times. As shown in FIG. 32, when the number of revolutions of the main shaft 1a obtained from the angle sensor Sq of the subshaft gear 24 is 0 to 39 revolutions, the table processing section 114 of the control section 110 detects the detection result of the Hall detector Sr. When the detection information Ar of the voltage value LO is received from the magnet presence/absence detection unit 113, the number of rotations of the main shaft 1a corresponding to the rotation angle Ap is specified as the number of rotations of the main shaft 1a. This is defined as a region R1 in FIG. 32 where the number of revolutions of the main shaft 1a is 0 to 39 addresses.

On the other hand, even when the rotation speed of the main shaft 1a obtained from the angle sensor Sq of the auxiliary shaft gear 24 is 0 to 39 rotations, the table processing unit 114 of the control unit 110 detects the presence or absence of the magnet, which is the detection result of the Hall detector Sr. When the detection information Ar of the voltage value HI is received from the unit 113, the number of rotations obtained by adding 60 rotations to the number of rotations of the main shaft 1a corresponding to the rotation angle Aq is specified as the number of rotations of the main shaft 1a. This is defined as a region R3 in which the number of revolutions of the main shaft 1a is 60-99. Note that the table processing unit 114 of the control unit 110 detects the voltage value from the magnet presence/absence detection unit 113 as a Hall value when the rotation speed of the main shaft 1a obtained from the angle sensor Sq of the sub shaft gear 24 is 40 to 59 rotations. Due to the sensitivity of the device Sr, the strength of the magnet Mr, the mechanical accuracy of gears, etc., and the setting of the electrical threshold level, it becomes uncertain, and the reversal position from the voltage value Lo to HI may change. The rotation speed of the main shaft 1a corresponding to the rotation angle Aq is directly specified as the rotation speed of the main shaft 1a without considering the detection information Ar of the voltage value from the detection unit 113 . This is defined as a region R2 in which the number of revolutions of the main shaft 1a is 40-59.

Further, when the number of rotations of the spindle 1a exceeds 100 addresses and is within the region R4 shown in FIG. Since the value is uncertain, the rotation speed of the main shaft 1a is not used in the region R4 shown in FIG. As described above, in order to avoid erroneous determination, the rotation speed of the main shaft 1a obtained from the angle sensor Sq of the counter shaft gear 24 is 0 to 39 rotations, that is, the range in which the actual rotation speed of the main shaft 1a is 0 to 99 rotations. It is set to use only

In this manner, the control unit 110 can stably determine up to 99 addresses, ie, 99 rotations of the main shaft, from the timing chart of FIG. Therefore, the absolute encoder 100 can specify the amount of rotation for 99 rotations of the main shaft 1a and the rotation angle of 359.99° (less than 360°) by the action of these counting mechanisms 30 . The range of regions R1 to R4 in the timing chart of FIG. 32 can be appropriately set according to the sensitivity of the Hall detector Sr and the strength of the magnet Mr. can be set arbitrarily.

As described above, the threshold value of the voltage value of the Hall detector Sr can be adjusted by adjusting the distance between the magnet Mr and the Hall detector Sr using the magnet screw holder 41 and the screw hole 37c.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and includes all aspects included in the concept of the present invention and the scope of claims. Moreover, each configuration may be selectively combined as appropriate so as to achieve at least part of the above-described problems and effects. For example, the shape, material, arrangement, size, etc. of each component in the above embodiment may be changed as appropriate according to the specific usage of the present invention.

For example, the embodiment of the present invention has been described as an example in which the absolute encoder 100 has the swinging member 35 and the Hall detector Sr, but the present invention is not limited to this, as shown in FIGS. , the slide member 60 and the switch portion 61 may be provided.

In this case, the slide member 60 slides between the first position L1 and the second position L2 as the first cam portion 33a of the swing cam 33 rotates. The switch portion 61 is turned off when the slide member 60 is at the first position L1, and turned on when it is at the second position L2. In the modification of the absolute encoder 100, the slide member 60 and the switch portion 61 can further increase the detectable rotation amount range of the main shaft 1a when the absolute encoder 100 is downsized.

Further, the embodiment of the present invention has been described as an example in which the swinging member 35 has the first swinging portion 36, the second swinging portion 37, and the third swinging portion 38 as the absolute encoder 100. However, the present invention is not limited to this, and as shown in FIG. 35, the rocking member 35 may have various forms. It is also possible to replace the switch section 61 with a magnet, a Hall detector, a reed relay, or the like.

For example, as shown in FIG. 35, the rocking member 35 is a rectangular rod-shaped member, and is rockably supported by a rocking member shaft 42 provided in the central portion in the left-right direction. The swinging member 35 swings between the first position L1 and the second position L2 according to the rotation of the first cam portion 33a of the swinging cam 33, and the Hall detector Sr (not shown) swings. It is detected whether the magnet Mr of the member 35 is at the first position L1 or the second position L2. Even with such a configuration, when the absolute encoder 100 is miniaturized, the detectable rotation amount range of the main shaft 1a can be further increased.

DESCRIPTION OF SYMBOLS 1... Motor 1a... Main shaft 2... Base 2b... Bottom part 2c... Strut 2d... Right outer peripheral surface 2e... Left outer peripheral surface 2f... Rear outer peripheral surface 2g... Front outer peripheral surface 2h... Bearing holder part , 2i Bearing 2j Swing cam shaft holder 2k Swing member shaft holder 3 Case 3a Outer wall 3b Lid 5 Substrate 11 First transmission mechanism 15 Second transmission mechanism 17 Third transmission mechanism 20 Main shaft gear 20a First cylindrical portion 20b Second cylindrical portion 20c Communicating portion 20d Bottom surface 20e Press-fit portion 20f Bottom surface , 20g... Magnet holding part 20h... First worm gear part 22... Intermediate gear 22a... Right sliding part 22b... Left sliding part 22c... Through hole 22d... First worm wheel part 22e... Second Worm gear portion 23 Intermediate gear shaft 23a Right end 23b Left end 24 Counter shaft gear 24a Through hole 24b Second worm wheel portion 25 Magnet holder 25a Magnet holding portion 25b Axial portion 30 Counting mechanism 31 First spur gear portion 32 Second spur gear portion 33 Swing cam 33a First cam portion 33b Second cam portion 33c Through hole 33d, 33e sliding surface 34 rocking cam shaft 34a lower end 34b upper end 34c fixture 35 rocking member 36 first rocking portion 36a rear end , 36b... Sliding surface 36c... Elastic member attachment part 36d... Front end 37... Second swing part 37a... Left end 37b... Right end 37c... Screw hole 37d... Through hole 38... Third 3 rocking portion 38a rear end 38b sliding surface 38c elastic member mounting portion 38d front end 38e through hole 39 elastic member 40 detector 41 magnet screw holder 42 Swing member shaft 42a Lower end 42b Upper end 51 Leaf spring 51a One end 51b Other end 52, 54, 55 Wall 53 Screw 54, 55 Wall Part 54a, 55a... Fixing tool 60... Slide member 61... Switch part 100... Absolute encoder 110... Control part 111, 112... Rotation angle acquisition part 113... Magnet presence/absence detection part 114... Table processing part , 114a...correspondence table, 115...rotation amount specifying unit, 116...output unit, Ap, Aq...angle information, Ar...detection information, BC...center axis of bearing, GmC...center axis of main shaft gear, GsC...subshaft Central axis of gear, L1... First position, L2... Second position, MoC... Central axis of main shaft of motor, Mp, Mq, Mr... Magnet, MpC, MqC, MrC... Central axis of magnet, MsC... Magnet Central axis of screw holder, R1 to R4... area, SC... central axis of magnet holder, ShC... central axis of screw hole, Sp, Sq... angle sensor, Sr... hall detector, SrC... central axis of hall detector

Claims (6)

An absolute encoder that specifies the amount of rotation over multiple revolutions of a spindle,
a first driving gear that rotates according to the rotation of the main shaft;
a first driven gear that meshes with the first drive gear;
a second driving gear that rotates according to the rotation of the first driven gear;
a second driven gear that meshes with the second drive gear;
a counting mechanism that specifies the number of rotations of the subshaft gear that rotates according to the rotation of the second driven gear ;
The counting mechanism is
a third driving gear that rotates according to the rotation of the second driven gear;
a third driven gear meshing with the third drive gear;
a first cam portion that rotates according to the rotation of the third driven gear;
a swinging member swinging between a first position and a second position according to the rotation of the first cam;
and a detector for detecting whether the swinging member is at the first position or at the second position . The rocking member is
a first oscillating portion slidable with the first cam portion and oscillating as it slides with the first cam portion;
One end is connected to the first oscillating portion, and the other end oscillates between the first position and the second position according to the oscillating movement of the first oscillating portion. a second oscillating part having a moving magnet,
2. The absolute encoder according to claim 1 , wherein said detector is a Hall detector for detecting whether said magnet is at said first position or at said second position. further comprising a second cam portion that rotates according to the rotation of the third driven gear;
The rocking member is
In a plan view, the first cam portion and the second cam portion extend so as to be sandwiched between the first swing portion and the second cam portion, and are slidable with the second cam portion. a third oscillating portion that oscillates according to sliding with the portion;
3. The absolute encoder according to claim 2 , further comprising an elastic member that attracts said first swinging portion and said third swinging portion to each other. An absolute encoder that specifies the amount of rotation over multiple revolutions of a spindle,
a first driving gear that rotates according to the rotation of the main shaft;
a first driven gear that meshes with the first drive gear;
a second driving gear that rotates according to the rotation of the first driven gear;
a second driven gear that meshes with the second drive gear;
a counting mechanism that specifies the number of rotations of the subshaft gear that rotates according to the rotation of the second driven gear;
The counting mechanism is
a third driving gear that rotates according to the rotation of the second driven gear;
a third driven gear meshing with the third drive gear;
a first cam portion that rotates according to the rotation of the third driven gear;
a slide member that slides between a first position and a second position according to the rotation of the first cam;
and a switch section that is turned off when the slide member is at the first position and turned on when the slide member is at the second position. a first angle sensor that detects the rotation angle of the main shaft;
5. The absolute encoder according to any one of claims 1 to 4, further comprising a second angle sensor for detecting a rotation angle of said countershaft gear. further comprising an intermediate gear on which the first driven gear and the second drive gear are provided;
5. The absolute according to claim 1, wherein the rotation axis of said main shaft is at a twisted position with respect to the rotation axis of said intermediate gear, and is provided parallel to the rotation axis of said second driven gear. encoder.

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