Rotating device

Abstract

Provided is a rotating device 100 capable of positioning a rotating member 102 at a target angle position with high accuracy. The rotating device 100 comprises a fine movement mechanism 109 that is provided with a base member 110 and a coarse movement mechanism 101 that is provided with a housing 104 and a rotating member 102 at least part of which is housed in the housing 104 and that is disposed on the base member 110. The rotating member 102 is capable of rotating about a rotating member axis 103 with respect to the housing 104, and the entire coarse movement mechanism 101 is capable of rotating about the rotating member axis 103 with respect to the base member 110.

Description

Rotating device

[0001] The present invention relates to a rotating device capable of positioning a rotating member at a target angular position with high precision.

[0002] Generally, a rotating device has an input shaft to which a driving force such as that of a motor is input, and an output shaft to which a rotating table for loading a machining workpiece of a machine tool or the like is attached. The current angular position of the rotating table is detected by an angle detector attached to the input shaft or the output shaft, and the rotating table is rotated and positioned at the target angular position by controlling a motor or the like.

[0003] Patent Document 1 discloses a roller turret cam index device provided rotatably around two rotation axes that intersect three-dimensionally with each other, and including roller gears and roller gear cams that mesh with each other. In this roller turret cam index device, in order to rotate the roller gear, the roller gear cam is rotated by a motor, an encoder is fixed to the housing, the input shaft of the encoder is non-rotatably connected to the roller gear shaft of the roller gear, and the rotation stop position of the roller gear is detected by the encoder.

[0004] Japanese Patent Application Laid-Open No. 2000-158293, Japanese Patent Application Laid-Open No. 2006-98392, Japanese Patent Application Laid-Open No. 2011-99802, Japanese Patent Application Laid-Open No. 2011-99804

[0005] In the roller turret cam index device of Patent Document 1, when the roller gear is rotated via the roller gear cam by a motor, there is a problem that the roller gear cannot be positioned with high precision because rotational frictional torque or the like inhibits the response from the motor to the roller gear.

[0006] Therefore, an object of the present invention is to solve the above problems and provide a rotating device capable of positioning a rotating member at a target angular position with high precision.

[0007] According to one aspect of the present invention, a rotating device includes a fine movement mechanism including a base member, and a coarse movement mechanism including a housing and a rotating member at least partially housed in the housing, the coarse movement mechanism being disposed on the base member, the rotating member being rotatable about a rotating member axis with respect to the housing, and the entire coarse movement mechanism being rotatable about the rotating member axis with respect to the base member.

[0008] According to one specific example of the present invention, in the rotating device, in order to position the rotating member at a target angular position, the coarse movement mechanism has a first angular resolution, and the fine movement mechanism has a second angular resolution smaller than the first angular resolution.

[0009] According to one specific example of the present invention, in the rotating device, the fine movement mechanism rotates the coarse movement mechanism within a range of an angle greater than or equal to the first angular resolution.

[0010] According to one specific example of the present invention, in the rotating device, the fine movement mechanism rotates the coarse movement mechanism within a range of an angle not more than twice the first angular resolution.

[0011] According to one specific example of the present invention, in the rotating device, the fine movement mechanism further includes a linear movement mechanism that contacts a part of the coarse movement mechanism, and by linearly moving the linear movement mechanism with respect to the base member, the entire coarse movement mechanism rotates about the rotating member axis with respect to the base member.

[0012] According to one specific example of the present invention, in the rotating device, the linear movement mechanism includes a first portion and a second portion respectively arranged so as to contact opposing surfaces of a part of the coarse movement mechanism, and by the first portion extending or contracting with respect to the second member, the linear movement mechanism linearly moves with respect to the base member.

[0013] According to one specific example of the present invention, in the rotating device, the ends of the first portion and the second portion respectively contact opposing surfaces of a part of the coarse movement mechanism such that when the first portion extends, the second portion contracts, and when the first portion contracts, the second portion extends, in order to rotate the coarse movement member.

[0014] According to one specific example of the present invention, in a rotating device, the first part comprises a first piezoelectric element, and by applying a voltage to the first piezoelectric element, the first piezoelectric element extends or contracts relative to the second member.

[0015] According to one specific example of the present invention, in a rotating device, the second part comprises an elastic member, the elastic member contracts relative to the first member when the first piezoelectric element extends, and extends relative to the first member when the first piezoelectric element contracts.

[0016] According to one specific example of the present invention, in a rotating device, the second part comprises a second piezoelectric element, and a voltage is applied to the second piezoelectric element such that the second piezoelectric element contracts relative to the first member when the first piezoelectric element expands, and expands relative to the first member when the first piezoelectric element contracts.

[0017] According to the present invention, the rotating device can position the rotating member to a target angular position with high precision.

[0018] Further objectives, features, and advantages of the present invention will become apparent from the following description of embodiments relating to the accompanying drawings.

[0019] This is a perspective view of a rotating device as one embodiment of the present invention. This is a side view of the rotating device of the embodiment of Figure 1. This is a top view and side view of the rotating device of the embodiment of Figure 1 when the fine adjustment mechanism is stopped. This is a top view and side view of the rotating device of the embodiment of Figure 1 when the coarse adjustment mechanism is stopped. This is a perspective view of the rotating device of the embodiment of Figure 1 equipped with an angle detector with a self-calibration function. This is a perspective view of the rotating device of the embodiment of Figure 1 equipped with a polyhedron and an autocollimator. This is a diagram showing a positioning control method as one embodiment of the present invention. This is a diagram showing one specific example of the positioning control method of the embodiment of Figure 5A. This is a diagram showing another perspective view of the inside of the coarse adjustment mechanism in the rotating device of the embodiment of Figure 1. This is a cross-sectional view of the rotating device of the embodiment of Figure 1 along the line A-A in Figure 2. This is a cross-sectional view of the rotating device of the embodiment of Figure 1 along the line B-B in Figure 2. This is a perspective view of the fine adjustment mechanism in the rotating device of the embodiment of Figure 1. This is a part of the top view of the fine adjustment mechanism in the rotating device of the embodiment of Figure 1. This is a part of the cross-sectional view of the fine adjustment mechanism in the rotating device of the embodiment of Figure 1 along the line C-C in Figure 2. This is a part of a cross-sectional view of a micro-movement mechanism different from the micro-movement mechanism in Figure 9A. This is a part of a cross-sectional view of a micro-movement mechanism different from the micro-movement mechanism in Figure 9A. This is a side view of a micro-movement mechanism in a rotating device as one embodiment of the present invention. This is a side view of a micro-movement mechanism in a rotating device as another embodiment of the present invention. This is a diagram showing the input voltage versus displacement characteristics of a piezoelectric element. This is a diagram showing the target displacement versus input voltage characteristics of a piezoelectric element.

[0020] The following describes embodiments of the present invention with reference to the drawings, but the present invention is not limited to these embodiments.

[0021] Referring to Figures 1 to 4B, a rotating device 100 as an embodiment of the present invention will be described. The rotating device 100 comprises a fine-movement mechanism 109 having a base member 110, and a coarse-movement mechanism 101 having a housing 104 and a rotating member 102 in which at least a part is housed within the housing 104. The rotating member 102 is an output shaft, and a rotary table for loading workpieces of a machine tool or the like may be provided at the end of the rotating member 102 as an output shaft. The rotary table rotates in conjunction with the rotating member 102 as it rotates around the axis 103 of the rotating member. The coarse-movement mechanism 101 is positioned on the base member 110. The rotating member 102 is rotatable relative to the housing 104 around the axis 103 of the rotating member. The entire coarse-movement mechanism 101 is rotatable relative to the base member 110 around the axis 103 of the rotating member. For example, as shown in Figure 3A, with the fine adjustment mechanism 109 stopped and the coarse adjustment mechanism 101 held at its current angular position relative to the base member 110, the coarse adjustment mechanism 101 rotates the rotating member 102 to a certain angular position relative to the housing 104 around the rotating member axis 103. Then, as shown in Figure 3B, with the coarse adjustment mechanism 101 stopped and the rotating member 102 held at that angular position relative to the housing 104, the fine adjustment mechanism 109 rotates the entire coarse adjustment mechanism 101 relative to the base member 110 around the rotating member axis 103, thereby rotating the rotating member 102 housed in the housing 104 to the target angular position. Alternatively, the coarse adjustment mechanism 101 and the fine adjustment mechanism 109 may be driven simultaneously to rotate the rotating member 102 to the target angular position, or the fine adjustment mechanism 109 may be driven first, followed by the coarse adjustment mechanism 101 to rotate the rotating member 102 to the target angular position.

[0022] To position the rotating member 102 at a target angular position, the coarse adjustment mechanism 101 has a first angular resolution that allows the rotating member 102 to be rotated and positioned relative to the housing 104, and the fine adjustment mechanism 109 has a second angular resolution smaller than the first angular resolution that allows the entire coarse adjustment mechanism 101 to be rotated and positioned relative to the base member 110. The angular position of the rotating member 102 relative to the base member 110 is detected by an angle detector. The angle detector may be an encoder, resolver, etc. As shown in Figure 4A, the angle detector may be an angle detector 120A with a self-calibration function as disclosed in Patent Documents 2 to 4, which allows the current angular position of the rotating member 102 relative to the base member 110 to be detected with high resolution, and allows the rotating member 102 to be positioned at the target angular position with high precision. As shown in Figure 4B, the angle detector may include a polyhedron 120B mounted on the rotating member 102 and an autocollimator 120C provided on the outside of the rotating device 100. This allows the current angular position of the rotating member 102 relative to the base member 110 to be detected with high resolution, and the rotating member 102 to be positioned at the target angular position with high precision. The rotating device 100 may further include a control unit for controlling a coarse movement mechanism 101 and a fine movement mechanism 109 that position the rotating member 102 at the target angular position based on the current angular position of the rotating member 102 detected by the angle detector, a coarse movement drive unit for driving the coarse movement mechanism 101 based on a coarse movement command from the control unit, and a fine movement drive unit for driving the fine movement mechanism 109 based on a fine movement command from the control unit. For example, the current angular position of the rotating member 102 relative to the base member 110 is detected with the driving of the coarse movement mechanism 101 and the fine movement mechanism 109 stopped. Next, as shown in Figure 3A, the fine adjustment mechanism 109 is stopped, and with the coarse adjustment mechanism 101 held at its current angular position relative to the base member 110, the coarse adjustment mechanism 101 rotates the rotating member 102 relative to the housing 104 with a first angular resolution, around the rotating member axis 103, to an angular position near the target angular position.Then, as shown in Figure 3B, with the coarse adjustment mechanism 101 stopped and the rotating member 102 held at an angular position near the target angular position relative to the housing 104, the fine adjustment mechanism 109 rotates the entire coarse adjustment mechanism 101 around the axis 103 of the rotating member relative to the base member 110 with a second angular resolution, thereby rotating the rotating member 102 housed in the housing 104 to the target angular position. In this way, by using the coarse adjustment mechanism 101 and the fine adjustment mechanism 109 interchangeably, the rotating member 102 can be positioned at the target angular position with high precision over a wide angular range.

[0023] The fine adjustment mechanism 109 rotates the coarse adjustment mechanism 101 within an angular range greater than or equal to the first angular resolution. This prevents a dead zone from occurring where the rotating member 102 cannot be rotated to the target angular position with a second angular resolution. Alternatively, the fine adjustment mechanism 109 may rotate the coarse adjustment mechanism within an angular range less than or equal to twice the first angular resolution. This ensures that the rotating member 102 is reliably positioned at the target angular position with a second angular resolution.

[0024] Referring to Figure 5A, a positioning control method as one embodiment of the present invention will be described. Looking at Figure 5A, a rightward arrow indicates a positive value, a leftward arrow indicates a negative value, and both arrows indicate an absolute value. The current angular position of the rotating member 102 relative to the base member 110 is θ. ｃｕｒ The target angular position of the rotating member 102 relative to the base member 110 is θ ｔａｇ Therefore, the command angle amount θ of the rotating member 102 ｃｔｌ is, θ ｔａｇ -θ ｃｕｒ This is represented by the coarse motion mechanism 101 moving the rotating member 102 to the target angular position θ. ｔａｇ The coarse movement is Rθ, which is the amount of angle by which the rotating member 102 is rotated relative to the housing 104 from a reference angular position in order to position it, and the fine movement mechanism 109 moves the rotating member 102 to the target angular position θ ｔａｇ If Sθ is the amount of fine movement which is the amount of angle by which the entire coarse movement mechanism 101 is rotated from a reference angular position relative to the base member 110 in order to position it, then the target angular position θ ｔａｇ It is expressed as Rθ + Sθ. The first angular resolution is Rθｒｅｓ Let the maximum fine movement amount, which is the angular range within which the fine movement mechanism 109 can rotate the entire coarse movement mechanism 101 with respect to the base member 110, be Sθ. ｍａｘ Then, ｍａｘ Sθ ｒｅｓ ≧ Rθ

[0025] First, for the commanded angular amount θ ｃｔｌ , with respect to the target angular position θ ｔａｇ , let the coarse movement amount Rθ on the current angular position θ ｃｕｒ side be RθP, and the coarse movement amount Rθ on the side opposite to the current angular position θ ｔａｇ with respect to the target angular position θ ｃｕｒ be RθN. Then, RθP = int(θ ｔａｇ / Rθ ｒｅｓ ) × Rθ ｒｅｓ , RθN = (int(θ ｔａｇ / Rθ ｒｅｓ ) + 1) × Rθ ｒｅｓ are obtained. Here, int(x) is the integer part of x. To position the rotating member 102 at the target angular position θ ｔａｇ , the coarse movement mechanism 101 rotates the rotating member 102 with respect to the housing 104 such that the angular position of the rotating member 102 becomes the coarse movement amount RθP or RθN.

[0026] Next, for the commanded angular amount θ ｃｔｌ , with respect to the target angular position θ ｔａｇ and the current angular position θ ｃｕｒ , let the fine movement amount Sθ of the difference between the coarse movement amount RθP on the side of the current angular position θ ｔａｇ be SθP, and the fine movement amount Sθ of the difference between the coarse movement amount RθN on the side opposite to the current angular position θ ｃｕｒ and the target angular position θ ｔａｇ be SθN. Then, SθP (positive value) = θ ｔａｇ - RθP, SθN (negative value) = θ

[0027] Let the current fine movement amount Sθ of the entire coarse movement mechanism 101 with respect to the base member 110 be Sθ ｃｕｒ . When the rotating member 102 is rotated with respect to the housing 104 by the coarse movement amount RθP on the side of the current angular position θ ｔａｇ with respect to the target angular position θ ｃｕｒ side, the current fine movement amount Sθｃｕｒ SθP ０ Therefore, δθP = SθP ０ When -SθP is 0 or greater (as in Figure 5A), the target angular position θ is achieved by rotating the entire coarse movement mechanism 101 relative to the base member 110 by a fine movement amount SθP while the angular position of the rotating member 102 is at the coarse movement amount RθP. ｔａｇ The rotating member 102 can be positioned accordingly. On the other hand, δθP = SθP ０ -If SθP is less than 0, the amount of fine movement SθP exceeds the angular range in which the fine movement mechanism 109 can rotate the entire coarse movement mechanism 101 relative to the base member 110, and therefore the target angular position θ ｔａｇ The rotating member 102 cannot be positioned. δθP is the amount of rotation SθP ０ Since it is the difference between δθP and the micro-movement SθP, the larger the absolute value of δθP, the smaller the absolute value of the micro-movement SθP. Target angular position θ ｔａｇ The current angular position θ ｃｕｒ When the rotating member 102 is rotated relative to the housing 104 with the coarse movement RθN on the opposite side, the current fine movement Sθ ｃｕｒ SθN is the amount of rotational range of the coarse movement mechanism 101 relative to the base member 110. ０ Therefore, δθN = SθN ０ When -SθN is 0 or less, the target angular position θ is achieved by rotating the entire coarse movement mechanism 101 relative to the base member 110 by a fine movement amount SθN while the angular position of the rotating member 102 is at the coarse movement amount RθN. ｔａｇ The rotating member 102 can be positioned accordingly. On the other hand, δθN = SθN ０ -When SθN is greater than 0 (as in Figure 5A), the fine movement amount SθN exceeds the angular range in which the fine movement mechanism 109 can rotate the entire coarse movement mechanism 101 relative to the base member 110, and therefore the target angular position θ ｔａｇ The rotating member 102 cannot be positioned. δθN is the amount of rotation SθN ０ Since it is the difference between δθN and the micromovement SθN, the larger the absolute value of δθN, the smaller the absolute value of the micromovement SθN. ｍａｘ ≥ Rθ ｒｅｓBy satisfying this condition, the angular position of the rotating member 102 is always such that at least one of the coarse movement amounts RθP and RθN is always the target angular position θ ｔａｇ The rotating member 102 can be positioned accordingly.

[0028] Referring to Figures 5B to 5D, a specific example of a positioning control method as one embodiment of the present invention will be described. ｃｕｒ = 0, Rθ ｒｅｓ = 1, Sθ ｍａｘ = 1.5, Sθ ｃｕｒ = Sθ ｍａｘ Let / 2 = 0.75. As shown in Figure 5B, θ ｔａｇ If we set = 1, then RθP = 1 and RθN = 2. Also, if SθP = 0 and SθN = -1, SθP ０ = 0.75, SθN ０ = -0.75. Then, δθP = 0.75 and δθN = 0.25. In this case, the target angular position θ can be adjusted using only the coarse adjustment mechanism 101, without using the fine adjustment mechanism 109. ｔａｇ The rotating member 102 can be positioned at =1. As shown in Figure 5C, θ ｔａｇ If we set it to = 1.25, then RθP = 1 and RθN = 2. Also, if SθP = 0.25 and SθN = -0.75, SθP ０ = 0.75, SθN ０ = -0.75. Then, δθP = 0.5 and δθN = 0. Therefore, with the angular position of the rotating member 102 at coarse movement amounts RθP = 1 and RθN = 2, the entire coarse movement mechanism 101 can be rotated relative to the base member 110 to reach the target angular position θ ｔａｇ The rotating member 102 can be positioned at θ = 1.25, but since |δθP| > |δθN|, the state in which the angular position of the rotating member 102 is such that the coarse movement amount RθP = 1 is selected, and the entire coarse movement mechanism 101 is rotated relative to the base member 110 by a fine movement amount SθP = 0.25 to reach the target angular position θ ｔａｇ It is preferable to position the rotating member 102 at θ = 1.25. As shown in Figure 5D, ｔａｇ If we set it to = 1.75, then RθP = 1 and RθN = 2. Also, if SθP = 0.75 and SθN = -0.25, SθP ０ = 0.75, SθN ０= -0.75. Then, δθP = 0 and δθN = -0.5. Therefore, with the angular position of the rotating member 102 at coarse movement amounts RθP = 1 and RθN = 2, the entire coarse movement mechanism 101 is rotated relative to the base member 110, thereby achieving the target angular position θ ｔａｇ The rotating member 102 can be positioned at θ = 1.75, but since |δθP| < |δθN|, the state in which the angular position of the rotating member 102 is such that the coarse movement amount RθP = 2 is selected, and the entire coarse movement mechanism 101 is rotated relative to the base member 110 by a fine movement amount SθN = -0.25 to the target angular position θ ｔａｇ It is preferable to position the rotating member 102 at 1.75.

[0029] As shown in Figures 6 to 7B, the coarse motion mechanism 101 may further include a second rotating member 107 as an input shaft, which is rotatable about the second rotating member axis 108. The second rotating member 107 may be a cam having a screw-shaped cam rib, which is rotatable about the second rotating member axis 108 perpendicular to the rotating member axis 103. The rotating member 102 may have a plurality of bearings arranged along its circumferential direction as a transmission mechanism 106. A motor 105 is connected to the second rotating member 107, and the motor 105 drives the second rotating member 107 to rotate about the second rotating member axis 108, thereby transmitting the input torque of the second rotating member 107 to the rotating member 102, which is an output shaft meshing with the second rotating member 107, via the plurality of bearings as a transmission mechanism 106, causing the rotating member 102 to rotate about the rotating member axis 103. The motor 105 may be connected to the second rotating member 107 via a reduction mechanism. Each of the multiple bearings in the transmission mechanism 106 may be in rolling contact with the cam rib of the second rotating member 107, or it may be a roller follower or a cam follower. Each of the multiple bearings in the transmission mechanism 106 may include a shaft member, an outer ring portion rotatable along the outer circumferential surface of the shaft member, etc., and may be a rolling contact bearing including rollers, etc., between the shaft member and the outer ring portion, or a sliding contact bearing without rollers, etc. The shaft member may be directly fitted to the rotating member 102. The second rotating member 107 may be a drum-shaped cam (concave global cam), a cylindrical cam (barrel cam), a drum-shaped cam (convex global cam), etc. Depending on the shape of the cam of the second rotating member 107, the second rotating member 107 as the input shaft and the rotating member 102 as the output shaft may be in an externally tangent or internally tangent positional relationship. The meshing of the rotating member 102 and the second rotating member 107 allows the rotating member 102 to be firmly held against the housing 104 when the coarse motion mechanism 101 is stopped, enabling the rotating member 102 to remain stopped relative to the housing 104 with high precision.Furthermore, the coarse motion mechanism 101 only needs to be capable of transmitting the input torque of the second rotating member 107 to the rotating member 102 via the transmission mechanism 106. As shown in Figures 6 to 7B, the coarse motion mechanism 101 may employ a roller gear cam mechanism, a barrel cam mechanism, or a gear mechanism. In this way, by transmitting the input torque of the second rotating member 107 to the rotating member 102 via the transmission mechanism 106, the torque of the rotating member 102 can be increased, and the mass loaded onto the rotary table provided at the end of the rotating member 102 can be increased. Also, the coarse motion mechanism 101 does not necessarily have to include the second rotating member 107 as an input shaft. The coarse motion mechanism 101 may employ a direct drive motor in which the motor is directly connected to the rotating member 102 to rotate the rotating member 102.

[0030] The fine-motion mechanism 109 further comprises a linear-motion mechanism 111 that contacts a part 114 of the coarse-motion mechanism 101. The linear-motion mechanism 111 moves linearly relative to the base member 110, causing the entire coarse-motion mechanism 101 to rotate around the rotation member axis 103 relative to the base member 110. As shown in Figures 7B and 8A, the rotating device 100 may further comprise a bearing 115 having an inner ring portion 116 connected to the housing 104 and an outer ring portion 117 connected to the base member 110. The bearing 115 may also have rollers 118 between the inner ring portion 116 and the outer ring portion 117. The bearing 115 only needs to be capable of supporting the rotation of the coarse-motion mechanism 101 relative to the base member 110. The inner ring portion 116 may be integrated with the housing 104, and integration allows the coarse-motion mechanism 101 to rotate with high precision relative to the base member 110. When the linear motion mechanism 111 moves in a straight line, it presses against a part 114 of the coarse motion mechanism 101, causing the coarse motion mechanism 101 to rotate relative to the base member 110 via the bearing 115. The fine motion mechanism 109 may also include a sealing member 119 that seals the lubricant for lubricating the bearing 115.

[0031] As shown in Figure 8B, if Y is the distance between the rotating member axis 103 and the axis on which the linear motion mechanism 111 is positioned, L is the initial position which is the reference position of the linear motion mechanism 111, θ is the initial angular position which is the reference angular position of the inner ring portion 116 and the coarse motion mechanism 101 to which the inner ring portion 116 is connected, and δL is the position resolution of the linear motion mechanism 111 at the initial position L, then the second angular resolution δθ of the fine motion mechanism 109 at the initial angular position θ is expressed by the following equation: δθ = θ - (θ - δθ) = tan －１ (L / Y) - tan －１ ((L - δL) / Y) For example, if Y = 65 mm, L = 7.5 mm, and δL = 10 nm, then δθ = 0.03 arcsec (1 arcsec = 1 / 3600°). Maximum linear momentum δL of the linear motion mechanism 111 ｍａｘ If we set it to 9.5 μm, the linear motion mechanism 111 will log in to control the linear motion in units of 10 nm. ２ If it has a resolution of (9.5 μm / 10 nm) ≈ 10 bits, the fine-movement mechanism 109 can rotate the coarse-movement mechanism 101 relative to the base member 110 with a tiny second angular resolution of less than 1 arcsec, such as 0.03 arcsec.

[0032] As shown in Figures 9A to 10C, the linear motion mechanism 111 may include a first portion 112 and a second portion 113, respectively, which are arranged to contact opposing surfaces of a part 114 of the coarse motion mechanism 101. The linear motion mechanism 111 moves linearly relative to the base member 110 as the first portion 112 extends relative to the second portion 113 and the second portion 113 contracts relative to the first portion 112, or as the first portion 112 contracts relative to the second portion 113 and the second portion 113 extends relative to the first portion 112. When the first portion 112 extends and presses against one surface of the part 114 of the coarse motion mechanism 101, it rotates the coarse motion mechanism 101 in one direction relative to the base member 110 via the bearing 115. Furthermore, when the second portion 113 extends and presses against the opposite surface of the part 114 of the coarse motion mechanism 101, it causes the coarse motion mechanism 101 to rotate in the opposite direction to the base member 110 via the bearing 115.

[0033] The ends of the first portion 112 and the second portion 113 contact opposing surfaces of a part 114 of the coarse movement mechanism 101, such that when the first portion 112 extends, the second portion 113 contracts, and when the first portion 112 contracts, the second portion 113 extends, in order to rotate the coarse movement member 101. As shown in Figures 9A and 9B, seats 121A may be formed on the opposing surfaces of the part 114 of the coarse movement mechanism 101. The corresponding end of either the first portion 112 or the second portion 113 contacts each seat 121A. The ends of the first portion 112 and the second portion 113 may be formed in a hemispherical shape. By making the shape of each end of the first portion 112 and the second portion 113 hemispherical, the corresponding ends can smoothly contact each seat portion 121A, and as the linear motion mechanism 111 moves linearly, the fine motion mechanism 109 can smoothly rotate the entire coarse motion mechanism 101 relative to the base member 110. Furthermore, each seat portion 121A may be formed in a concave conical shape as shown in Figure 9A, or in a convex hemispherical shape as shown in Figure 9B. As shown in Figure 9C, the ends of the first portion 112 and the second portion 113 may contact the corresponding surface of one of the opposing surfaces of a part 114 of the coarse motion mechanism 101 via a bendable hinge 121B. As the linear motion mechanism 111 moves linearly, the fine motion mechanism 109 can smoothly rotate the entire coarse motion mechanism 101 relative to the base member 110 via the hinge 121B.

[0034] The first portion 112 may include a first piezoelectric element 126, as shown in Figure 10A. As shown in Figure 11A, piezoelectric elements generally displace when an input voltage is applied; they expand when the input voltage increases and contract when the input voltage decreases. Therefore, by applying a voltage to the first piezoelectric element 126, the first piezoelectric element 126 expands or contracts relative to the second portion 113. The second portion 113 may also include an elastic member 127, as shown in Figure 10A. The elastic member 127 may be a coil spring, a disc spring, a rubber spring, etc. The elastic member 127 is set to contract relative to the first piezoelectric element 126 when the first piezoelectric element 126 expands, and to expand relative to the first piezoelectric element 126 when the first piezoelectric element 126 contracts. As shown in Figure 11B, a voltage is applied to the first piezoelectric element 126 so that it extends by an amount of displacement corresponding to the predetermined angular amount, in order for the first piezoelectric element 126 to press against one surface of a part 114 of the coarse motion mechanism 101, causing the coarse motion mechanism 101 to rotate in one direction by a predetermined angular amount relative to the base member 110 via the bearing 115. Also, as shown in Figure 11B, a voltage is applied to the first piezoelectric element 126 so that it contracts by an amount of displacement corresponding to the predetermined angular amount, in order for the elastic member 127 to press against the other surface of the part 114 of the coarse motion mechanism 101 opposite to the one surface, causing the coarse motion mechanism 101 to rotate in the other direction opposite to the one direction relative to the base member 110 by a predetermined angular amount, in order for the first piezoelectric element 126 to contract. In this way, by controlling the voltage of the first piezoelectric element 126, the rotating member 102 can be positioned at the target angular position with high precision of 1 arcsec or less.

[0035] The first portion 112 and the second portion 113 may be completely fixed to the base member 110. Also, as shown in Figure 10A, the first portion 112 may be provided with a first linear guide 122 for guiding the extension or contraction of the first portion 112, and the second portion 113 may be provided with a second linear guide 123 for guiding the extension or contraction of the second portion 113. Furthermore, the first portion 112 may be provided with a first adjustment screw 124 for adjusting the position of the first portion 112 and applying preload to a part 114 of the coarse movement mechanism 101, and the second portion 113 may be provided with a second adjustment screw 125 for adjusting the position of the second portion 113 and applying preload to a part 114 of the coarse movement mechanism 101.

[0036] The second portion 113 may include a second piezoelectric element 128, as shown in Figure 10B. A voltage is applied to the second piezoelectric element 128 such that it contracts relative to the first portion 112 when the first piezoelectric element 126 extends, and extends relative to the first portion 112 when the first piezoelectric element 126 contracts. The first piezoelectric element 126 and the second piezoelectric element 128 allow the fine adjustment mechanism 109 to firmly hold the coarse adjustment mechanism 101 when the fine adjustment mechanism 109 is stopped. As shown in Figure 11B, voltages corresponding to the first piezoelectric element 126 and the second piezoelectric element 128 are applied to each of them, such that the first piezoelectric element 126 presses against one surface of a part 114 of the coarse motion mechanism 101, causing the coarse motion mechanism 101 to rotate in one direction by a predetermined angular amount relative to the base member 110 via the bearing 115, so that the first piezoelectric element 126 extends by an amount of displacement corresponding to that predetermined angular amount, and the second piezoelectric element 128 contracts by an amount of displacement corresponding to that predetermined angular amount. Furthermore, as shown in Figure 11B, voltages corresponding to the first piezoelectric element 126 and the second piezoelectric element 128 are applied so that the second piezoelectric element 128 presses against the other surface of a part 114 of the coarse motion mechanism 101 opposite to one surface, causing the coarse motion mechanism 101 to rotate relative to the base member 110 by a predetermined angular amount via the bearing 115, the second piezoelectric element 128 extends by an amount of displacement corresponding to that predetermined angular amount, and the first piezoelectric element 126 contracts by an amount of displacement corresponding to that predetermined angular amount. The extension of the first piezoelectric element 126 and the contraction of the second piezoelectric element 128 may occur simultaneously, or the contraction of the first piezoelectric element 126 and the extension of the second piezoelectric element 128 may occur simultaneously. Furthermore, in order to reliably prevent the extension of the first piezoelectric element 126 or the second piezoelectric element 128 from occurring first, the extension of the first piezoelectric element 126 may occur after the contraction of the second piezoelectric element 128, or the extension of the second piezoelectric element 128 may occur after the contraction of the first piezoelectric element 126. By controlling the voltages of the first piezoelectric element 126 and the second piezoelectric element 128 in this way, the rotating member 102 can be positioned at the target angular position with high precision of 1 arcsec or less.

[0037] The first part 112 may include a ball screw comprising a screw 129 and a nut 130, as shown in Figure 10C. Alternatively, a second motor 131 may be connected to the screw 129 to rotate the screw 129 and cause the nut 130 to move in a linear motion. The second motor 131 rotates the screw 129 so that the nut 130 presses against one surface of part 114 of the coarse motion mechanism 101, causing the coarse motion mechanism 101 to rotate by a predetermined angular amount in one direction relative to the base member 110 via the bearing 115, and the nut 130 moves forward toward part 114 of the coarse motion mechanism 101 by a displacement amount corresponding to that predetermined angular amount. Furthermore, the elastic member 127 presses against the opposite surface of a part 114 of the coarse motion mechanism 101, causing the coarse motion mechanism 101 to rotate by a predetermined angular amount relative to the base member 110 in the opposite direction via the bearing 115. The second motor 131 rotates the screw 129 so that the nut 130 retracts from the part 114 of the coarse motion mechanism 101 by an amount of displacement corresponding to that predetermined angular amount. By controlling the rotation of the screw 129 in this way, the rotating member 102 can be positioned at the target angular position with high precision of 1 arcsec or less. The first part 112 and the second part 113 may include electric, hydraulic, or pneumatic cylinders, actuators, etc.

[0038] Although the above description is based on specific embodiments, it will be apparent to those skilled in the art that the present invention is not limited thereto, and various changes and modifications can be made within the scope of the principles of the present invention and the appended claims.

[0039] 100 Rotating device 101 Coarse motion mechanism 102 Rotating member 103 Rotating member axis 104 Housing 105 Motor 106 Transmission mechanism 107 Second rotating member 108 Second rotating member axis 109 Fine motion mechanism 110 Base member 111 Linear motion mechanism 112 First part 113 Second part 114 Part of coarse motion mechanism 115 Bearing 116 Inner ring part 117 Outer ring part 118 Roller 119 Seal member 120A Angle detector with self-calibration function 120B Polyhedron 120C Autocollimator 121A Seat part 121B Hinge 122 First linear guide 123 Second linear guide 124 First adjustment screw 125 Second adjustment screw 126 First piezoelectric element 127 Elastic member 128 Second piezoelectric element 129 Screw 130 Nut 131 Second motor

Claims

1. A rotating device comprising a fine-motion mechanism having a base member, and a coarse-motion mechanism having a housing and a rotating member, at least a portion of which is housed within the housing, the coarse-motion mechanism being positioned on the base member, wherein the rotating member is rotatable about the axis of the rotating member relative to the housing, and the entire coarse-motion mechanism is rotatable about the axis of the rotating member relative to the base member.

2. The rotating device according to claim 1, wherein the coarse adjustment mechanism has a first angular resolution and the fine adjustment mechanism has a second angular resolution smaller than the first angular resolution, in order to position the rotating member at a target angular position.

3. The rotating device according to claim 2, wherein the fine adjustment mechanism rotates the coarse adjustment mechanism within an angle range greater than or equal to the first angular resolution.

4. The rotating device according to claim 3, wherein the fine adjustment mechanism rotates the coarse adjustment mechanism within an angle range of twice or less the first angular resolution.

5. The rotating device according to any one of claims 1 to 4, wherein the fine-motion mechanism further comprises a linear-motion mechanism that contacts a part of the coarse-motion mechanism, and the entire coarse-motion mechanism rotates around the axis of the rotating member with respect to the base member by the linear motion of the linear-motion mechanism with respect to the base member.

6. The rotary device according to claim 5, wherein the linear motion mechanism comprises a first part and a second part, respectively, arranged to contact opposing surfaces of a part of the coarse motion mechanism, and the linear motion mechanism moves linearly relative to the base member by the extension or contraction of the first part relative to the second member.

7. The rotating device according to claim 6, wherein the ends of the first portion and the second portion each contact the opposing surfaces of a part of the coarse moving mechanism such that when the first portion extends, the second portion contracts, and when the first portion contracts, the second portion extends, in order to rotate the coarse moving member.

8. The rotating device according to claim 6, wherein the first part comprises a first piezoelectric element, and by applying a voltage to the first piezoelectric element, the first piezoelectric element extends or contracts relative to the second member.

9. The rotating device according to claim 8, wherein the second part comprises an elastic member, the elastic member contracting relative to the first member when the first piezoelectric element extends, and extending relative to the first member when the first piezoelectric element contracts.

10. The rotating device according to claim 8, wherein the second part comprises a second piezoelectric element, and a voltage is applied to the second piezoelectric element such that the second piezoelectric element contracts relative to the first member when the first piezoelectric element expands, and expands relative to the first member when the first piezoelectric element contracts.

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