Rotational solid drive device and position sensor unit used in same

Abstract

A rotational solid drive device has a rotational solid provided with external teeth, a drive gear that meshes with the external teeth of the rotational solid and rotates around a rotational center line parallel to the rotational center line of the rotational solid, and a position detection unit that detects the rotational angular position of the rotational solid. The position detection unit includes a base member, a turning member supported by the base member so as to be capable of turning about a first rotational center line parallel to the rotational center line of the rotational solid, a first gear that is supported by the turning member so as to be capable of rotating about a second rotational center line parallel to the first rotational center line and that meshes with the external teeth of the rotational solid, and a sensor provided to the turning member to detect the rotational angular position of the first gear.

Description

Rotating body driving device and position sensor unit used therein

[0001] The present disclosure relates to a rotating body driving device that rotates a rotating body and a position sensor unit used therein.

[0002] For example, Patent Document 1 discloses a device for rotating a worm wheel (rotating body). A worm (drive gear) that meshes with the external teeth of the worm wheel is rotated by a motor. The worm gear is supported on a support base attached to the tip (free end) of a leaf spring. The leaf spring biases the worm toward the worm wheel. This eliminates backlash between the worm wheel and the worm. By eliminating the backlash, the rotational angle position of the worm wheel can be adjusted with high precision by the motor.

[0003] Japanese Patent Application Laid-Open No. 2017-67247

[0004] The present disclosure aims to adjust the rotational angle position of a rotor with high precision in a rotor drive device having a rotor with external teeth and a drive gear that rotates the rotor, regardless of whether or not there is backlash between the external teeth of the rotor and the drive gear.

[0005] In order to solve the above-mentioned problems, according to one aspect of the present disclosure, there is provided a rotary body drive device having: a rotary body having external teeth; a drive gear that meshes with the external teeth of the rotary body and rotates about a rotation center line parallel to the rotation center line of the rotary body; and a position detection unit that detects the rotational angle position of the rotary body, wherein the position detection unit includes: a base member; a rotary member supported on the base member so as to be rotatable about a first rotation center line parallel to the rotation center line of the rotary body; a first gear that is supported on the rotary member so as to be rotatable about a second rotation center line parallel to the first rotation center line and that meshes with the external teeth of the rotary body; and a sensor provided on the rotary member for detecting the rotational angle position of the first gear.

[0006] According to another aspect of the present disclosure, there is provided a position sensor unit for detecting the rotational angle position of a rotating body having external teeth, the position detection unit comprising: a base member; a rotating member supported on the base member so as to be rotatable about a first rotational center line parallel to the rotational center line of the rotating body; a first gear supported on the rotating member so as to be rotatable about a second rotational center line parallel to the first rotational center line, the first gear meshing with the external teeth of the rotating body; and a sensor provided on the rotating member for detecting the rotational angle position of the first gear.

[0007] According to the present disclosure, in a rotary body drive device having a rotary body with external teeth and a drive gear that rotates the rotary body, the rotational angle position of the rotary body can be adjusted with high precision regardless of whether or not there is backlash between the rotary body, the external teeth, and the drive gear.

[0008] 1 is a schematic perspective view of a projector equipped with a lens driving device according to an embodiment of the present disclosure; 2 is a perspective view of the lens driving device; 3 is an exploded perspective view of the lens barrel; 4 is an exploded perspective view of the position detection unit; 5 is a cross-sectional view showing the meshing of the second gear and the third gear; 6 is a diagram showing the casing of the position detection unit being biased by a biasing member;

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of well-known matters or redundant explanation of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following explanation and to facilitate understanding by those skilled in the art.

[0010] The inventor(s) provide the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure, and do not intend for them to limit the subject matter described in the claims.

[0011] Hereinafter, an imaging device according to an embodiment of the present disclosure will be described with reference to the drawings.

[0012] Fig. 1 is a schematic perspective view of a projector equipped with a lens driving device according to an embodiment of the present disclosure, Fig. 2 is a perspective view of the lens driving device, and Fig. 3 is an exploded perspective view of the lens driving device.

[0013] The X-Y-Z Cartesian coordinate system shown in the figure is for facilitating understanding of the embodiments of the present disclosure, and does not limit the embodiments of the present disclosure. The X-axis direction is the front-to-rear direction of the projector, the Y-axis direction is the left-to-right direction, and the Z-axis direction is the height direction.

[0014] As shown in Fig. 1, projector 10 has a housing 12 and a lens drive device 14 (rotating body drive device) mounted on housing 12. As shown in Fig. 2 and Fig. 3, lens drive device 14 includes a lens barrel 18 equipped with a lens 16, and a lens drive module 20 that shifts lens 16 of lens barrel 18 in the extension direction of its optical axis C (X-axis direction). First, lens barrel 18 will be described.

[0015] FIG. 4 is an exploded perspective view of the lens barrel.

[0016] 4, lens barrel 18 includes a cylindrical lens support member 22 that supports lens 16, and a cylindrical barrel main body 24 that supports lens support member 22 so that it can shift in the extension direction of optical axis C (X-axis direction). Lens barrel 18 is attached to housing 12 of projector 10 via barrel main body 24.

[0017] Specifically, the lens support member 22 is stored in the barrel body 24 so as to be shiftable in the direction in which the optical axis C extends (the X-axis direction). A plurality of guide pins 26 are provided on the outer peripheral surface of the lens support member 22. A plurality of guide holes 24a that guide the plurality of guide pins 26 are provided in the barrel body 24. The guide holes 24a extend in the direction in which the optical axis C extends.

[0018] The lens barrel 18 also includes a cam unit 28 for shifting the lens support member 22 in the direction in which the optical axis C extends (the X-axis direction). The cam unit 28 is composed of a cylindrical outer cam 30 that is fitted onto the lens barrel main body 24, and an inner cam 32 that is fitted onto the lens support member 22 while being fitted into the lens barrel main body 24.

[0019] The outer cam 30 of the cam unit 28 is supported by the barrel main body 24 so as to be rotatable in the circumferential direction of the outer peripheral surface of the barrel main body 24. Specifically, a plurality of guide pins 34 are provided on the inner peripheral surface of the outer cam 30. A plurality of guide holes 24b that guide the plurality of guide pins 34 are provided in the housing main body 24. The guide holes 24b extend in the circumferential direction of the outer peripheral surface of the housing main body 24.

[0020] The guide pins 34 are fixed to the outer cam 30. The guide pins 34 also engage with a plurality of engagement holes 32a provided in the inner cam 32. As a result, the outer cam 30 and the inner cam 32 are integrated.

[0021] The inner cam 32 of the cam unit 28 is formed with a plurality of cam grooves 32b that move each of the plurality of guide pins 26 provided on the lens support member 22. The cam grooves 32b extend in the circumferential direction of the outer circumferential surface of the inner cam 32, and also extend in the extension direction of the optical axis C (X-axis direction). As a result, when the inner cam 32 rotates in the circumferential direction along the outer circumferential surface of the lens support member 22, the cam grooves 32b move the guide pins 26 in the extension direction of the optical axis C.

[0022] With this lens barrel 18, when the outer cam 30 of the cam unit 28 rotates about the optical axis C, the inner cam 32 connected to the outer cam 30 rotates in the same direction. The rotation of the inner cam 32 causes the cam groove 32b of the inner cam 32 to shift the lens support member 22, i.e., the lens 16, via the guide pin 26 in the direction in which the optical axis C extends (the X-axis direction). By shifting the lens 16 in the direction in which the optical axis C extends, the focus of the image projected through the lens 16 is adjusted.

[0023] In this embodiment, as shown in FIGS. 2 and 3, the outer cam 30 (rotating body) of the cam unit 28 of the lens barrel 18 is rotated by the lens driving module 20 .

[0024] 2 and 3, the lens driving module 20 includes a base member 40, a driving gear 42 that rotates the outer cam 30 of the cam unit 28 of the lens barrel 18, and a motor 44 that rotates the driving gear 42. In the present embodiment, the lens driving module 20 is provided on the lens housing 18 by fixing the base member 40 to the housing main body 24 via fixing screws 46, as shown in FIG. 3. In the present embodiment, a reduction mechanism 48 is provided between the driving gear 42 and the motor 44.

[0025] The drive gear 42 is a so-called spur gear, and is rotated by the motor 44 around a rotation center line R0 extending in the extension direction of the optical axis C (X-axis direction). As shown in FIG. 2 , in order to be rotated by the drive gear 42, the outer cam 30 of the cam unit 28 is formed with external teeth 30a extending in its circumferential direction. The external teeth 30a are so-called spur gear-like teeth. When the drive gear 42 meshing with the external teeth 30a is rotated by the motor 44, the outer cam 30 rotates around the optical axis C. Note that the motor 44 is controlled by a controller 50 provided in the housing 12 of the projector 10, as shown in FIG. 1 . The controller 50 is, for example, a board on which circuits, a processor, etc. are provided.

[0026] In this embodiment, a position detection unit 60 is provided to allow the motor 44 to adjust the rotational angle position of the outer cam 30, and to adjust the position of the lens 16 in the extension direction (X-axis direction) of the optical axis C. In this specification, the rotational angle position refers to the rotational angle from the reference position.

[0027] FIG. 5 is an exploded perspective view of the position detection unit.

[0028] In the present embodiment, the position detection unit 60 is a part of the lens driving module 20. Specifically, as shown in Fig. 5, the position detection unit 60 includes a base member 40, a casing (rotating member) 62 supported by the base member 40, a first gear 64 supported by the casing 62, and a sensor 66 for detecting the rotational angle position of the first gear 64.

[0029] In this embodiment, the casing 62 is made up of a front casing 68 and a rear casing 70. For reasons that will be explained later, the casing 62 is supported by the base member 40 so as to be rotatable about the rotational center line of the outer cam 30, i.e., a first rotational center line R1 that is parallel to the optical axis C. Specifically, in this embodiment, a through-hole 68a is formed in the casing 62 (its front casing 68) and penetrates in the direction in which the first rotational center line R1 extends (the X-axis direction), and a support rod 72 is inserted through this through-hole 68a. One end of the support rod 72 is supported by the base member 40. A slit washer 74 is attached to the other end of the support rod 72 to prevent the casing 62 from falling off.

[0030] The first gear 64 is supported by the casing 62 so as to be rotatable about a second rotational center line R2 that is parallel to the first rotational center line R1. Furthermore, as shown in Figure 2, the first gear 64 meshes with the external teeth 30a of the outer cam 30. As a result, when the outer cam 30 rotates about the optical axis C, the first gear 64 rotates about the second rotational center line R2.

[0031] The sensor 66 is a position sensor such as a rotary encoder that detects the rotational angle position of the first gear 64. In the present embodiment, the sensor 66 is mounted on a board 76, which is attached to the casing 62. The board 76 is provided with a connector 78 for electrically connecting the sensor 66 to the controller 50 in the housing 12 of the projector 10.

[0032] In this embodiment, the rotational angle position of the first gear 64 is indirectly detected. Specifically, a second gear 80 and a third gear 82 are provided inside the casing 62.

[0033] The second gear 80 is a so-called spur gear. The second gear 80 is provided at one end of a shaft 84 that penetrates the front casing 68. The other end of the shaft 84 is connected to the first gear 64. That is, the first gear 64 and the second gear 80 are connected in the axial direction (X-axis direction) via the shaft 84. The shaft 84 is rotatably supported by a bearing 68b that is integrally formed with the front casing 68. In this embodiment, the second gear 80 and the shaft 84 are integrated.

[0034] FIG. 6 is a cross-sectional view showing the meshing between the second gear and the third gear.

[0035] As shown in Fig. 6, the third gear 82 meshes with the second gear 80 inside the casing 62. As shown in Fig. 5, the third gear 82 is a so-called spur gear, and is supported by the casing 62 so as to be rotatable about a third rotation center line R3 that is parallel to the second rotation center line R2. The third gear 82 is also connected to the sensor 66. The sensor 66 detects the rotational angle position of the third gear 82.

[0036] That is, in the present embodiment, the first gear 64 is connected to the sensor 66 via the second gear 80 and the third gear 82. As a result, the rotational angular position of the first gear 64 is indirectly detected. Specifically, the sensor 66 detects the rotational angular position of the third gear 82 and transmits a signal corresponding to the detection result to the controller 50. The controller 50 calculates the rotational angular position of the first gear 64 connected to the second gear 80 based on the signal from the sensor 66 and the gear ratio between the second gear 80 and the third gear 82. The controller 50 then calculates the rotational angular position of the outer cam 30 based on the calculated rotational angular position of the first gear 64 and the gear ratio between the external teeth 30 a of the outer cam 30 and the first gear 64. Since the relationship between the rotational angle position of the outer cam 30 and the position of the lens 16 in the extension direction (X-axis direction) of the optical axis C is a fixed relationship, the position of the lens 16 can be identified from the rotational angle position of the outer cam 30.

[0037] In order to detect the rotational angle position of the outer cam 30 with high accuracy, in this embodiment, to detect the position of the lens 16 with high accuracy, backlash is eliminated between the external teeth 30a of the outer cam 30 and the first gear 64. Specifically, as shown in FIG. 5 , the position detection unit 60 includes a biasing member 86 that biases the casing 62 so that the first gear 64 continues to contact the outer cam 30.

[0038] FIG. 7 is a diagram showing the casing of the position detection unit being biased by a biasing member.

[0039] 5 and 7, in this embodiment, the biasing member 86 is a torsion spring. The biasing member 86 is provided so that the support rod 72 passes through a coil portion 86a of the biasing member 86. One end 86b of the biasing member 86 is hooked to the base member 40, and the other end 86c is hooked to the casing 62.

[0040] Such a biasing member 86 causes the casing 62 to rotate about the first rotation center line R1 toward the outer cam 30, and the first gear 64 continues to contact the external teeth 30a of the outer cam 30.

[0041] 7, in the present embodiment, the casing 62 is positioned above the outer cam 30, and the weight of the casing 62 causes the first gear 64 to contact the external teeth 30a of the outer cam 30. To maintain this contact, the biasing member 86 continues to bias the casing 62 toward the outer cam 30.

[0042] Such a biasing member 86 can eliminate backlash between the external teeth 30a of the outer cam 30 and the first gear 64. As a result, there is a one-to-one correspondence between the rotational angle position of the outer cam 30 and the contact state between the external teeth 30a and the first gear 64. In other words, there is a one-to-one correspondence between the rotational angle position of the outer cam 30 and the rotational angle position of the first gear 64. As a result, the rotational angle position of the outer cam 30 can be detected with high accuracy via the first gear 64.

[0043] Note that the biasing member 86 biases the first gear 64 toward the external teeth 30a of the outer cam 30 via the casing 62, thereby increasing the torque load acting on the motor 44 that rotates the outer cam 30 (compared to when the first gear 64 is not biased). In this regard, it is preferable that the first gear 64 contact the external teeth 30a so that an excessive torque load is not applied to the motor 44.

[0044] To this end, as shown in FIG. 7 , the casing 62 is disposed relative to the outer cam 30 so that, when viewed in the direction (X-axis direction) of extension of the rotation center line (i.e., optical axis C) of the outer cam 30, a straight line L1 connecting the first rotation center line R1 and the second rotation center line R2 is perpendicular to a straight line L2 connecting the optical axis C and the second rotation center line R2. As a result, a biasing force F1 from the biasing member 86 via the first gear 64 acts on the outer cam 30 toward the optical axis C. Note that in FIG. 7 , the outline arrow indicating the biasing force F1 is shifted so as not to overlap with the second straight line L2. As a result, the torque load acting on the motor 44 during forward rotation of the outer cam 30 and the torque load acting during reverse rotation become substantially the same and are reduced.

[0045] In the present embodiment, in addition to the meshing between the external teeth 30a of the outer cam 30 and the first gear 64, there is also meshing between the second gear 80 and the third gear 82. In order to detect the rotational angle position of the outer cam 30 with high accuracy, it is necessary to eliminate backlash between the second gear 80 and the third gear 82 as much as possible.

[0046] Fig. 8 is a front view of the casing of the position detection unit, and Fig. 9 is a view showing a state in which the second gear has shifted toward the third gear.

[0047] 8 and 9 , in this embodiment, in order to eliminate backlash between the second gear 80 and the third gear 82 as much as possible, a protrusion 68c is provided on the inner surface of the cylindrical bearing 68b of the front casing 68 of the casing 62. In this embodiment, the cross section of the through hole in the bearing 68b is formed in a "D" shape, so that the protrusion 68c is provided on the inner surface of the bearing 68b. This protrusion 68c, together with the reaction force F2 from the external teeth 30b of the outer cam 30 that the first gear 64 receives, eliminates backlash between the second gear 80 and the third gear 82 as much as possible.

[0048] 7, when the biasing force F1 of the biasing member 86 acts on the external teeth 30a of the outer cam 30 via the first gear 64, a reaction force F2 is generated from the external teeth 30a toward the first gear 64. The reaction force F2 has the same magnitude as the biasing force F1 and is a force in the opposite direction to the biasing force F1.

[0049] Due to the reaction force F2 acting on the first gear 64, the shaft 84 connected to the first gear 64 shifts in the direction of the reaction force F2. However, when the shaft 84 comes into contact with the protrusion 68c in the bearing 68b, the shaft 84 shifts in a direction S different from the direction of the reaction force F. By providing the protrusion 68c at an appropriate position on the inner surface of the bearing 68b, the shaft 84 shifts in a direction approaching the third rotation center line R3. As a result, the second gear 80 connected to the shaft 84 shifts toward the third gear 82, thereby eliminating backlash between the second gear 80 and the third gear 82 as much as possible. This elimination of backlash is achieved by the existence of a small gap between the inner surface of the bearing 68b and the shaft 84, since the bearing 68b rotatably supports the shaft 84.

[0050] Note that such backlash cannot be eliminated when the third gear 82 is positioned in the direction of the biasing force F1 relative to the second gear 80. In other words, the relative positions of the second gear 80 (i.e., the first gear 64) and the third gear 82 with respect to the outer cam 30 are determined so as to enable elimination of such backlash.

[0051] As described above, by eliminating backlash between the external teeth 30a of the outer cam 30 and the first gear 64 and between the second gear 80 and the third gear 82, the sensor 66 can detect the rotational angle position of the outer cam 30 with high accuracy.

[0052] Furthermore, the controller 50 performs feedback control of the motor 44 based on the rotational angle position of the outer cam 30 detected with high precision, thereby enabling high-precision adjustment of the rotational angle position of the outer cam 30. That is, in the present embodiment, the position of the lens 16 in the extension direction of the optical axis C (X-axis direction) can be adjusted with high precision.

[0053] Although the embodiments of the present disclosure have been described above with reference to the above-mentioned embodiments, the embodiments of the present disclosure are not limited to these.

[0054] For example, in the above-described embodiment, as shown in Fig. 7, the biasing member 86 that biases the first gear 64 in the position detection unit 60 is a torsion spring. However, the embodiment of the present disclosure is not limited to this. The biasing member 86 may be a member other than a torsion spring as long as it can rotate the casing 62 that supports the first gear 64 about the first rotation center line R1.

[0055] In the above-described embodiment, as shown in FIG. 7 , the first gear 64 is urged toward the external teeth 30a of the outer cam 30 by the urging member 86, thereby maintaining contact between the first gear 64 and the external teeth 30a of the outer cam 30. This eliminates backlash therebetween. However, the embodiment of the present disclosure is not limited to this. For example, a magnet may be used to maintain contact between the first gear 64 and the external teeth 30a of the outer cam 30. Alternatively, the weight of the casing 62, the sensor 66 provided on the casing 62, and the like may be used to maintain contact between the external teeth 30a of the outer cam 30 and the first gear 64.

[0056] Furthermore, in the above-described embodiment, the first gear 64 and the sensor 66 are connected via the second gear 80 and the third gear 82. However, the embodiment of the present disclosure is not limited to this. If possible, the first gear 64 may be directly connected to the sensor 66.

[0057] Furthermore, in the above-described embodiment, there is no particular configuration for eliminating backlash between the external teeth 30a of the outer cam 30 and the drive gear 42. Backlash between them may or may not be eliminated. In other words, regardless of the presence or absence of backlash between them, the rotational angle position of the outer cam 30 can be adjusted with high precision by feedback controlling the motor 44 based on the rotational angle position of the outer cam 30 detected with high precision by the position detection unit 60.

[0058] Additionally, in the above-described embodiment, the drive gear 42 that rotates the outer cam 30 is rotated by the motor 44. However, the embodiment of the present disclosure is not limited to this. The drive gear 42 may be rotated by a user via a dial knob, for example. In this case, the projector 10 is provided with a display that presents to the user the position of the lens corresponding to the rotational angle position of the outer cam 30 detected by the position detection unit 60. The user can adjust the lens to a desired position by rotating the dial knob based on the lens position displayed on the display.

[0059] Additionally, in the above-described embodiment, the rotating body whose rotational angle position is detected is the outer cam 30 in the lens barrel 18 that shifts the lens 16 of the projector 10. However, the embodiments of the present disclosure are not limited to this. The rotating body whose rotational angle position is detected may be any rotating body that has external teeth.

[0060] Finally, because the embodiments of the present disclosure are intended to detect the rotational angular position of a rotating body that is stationary, it is not necessary to eliminate backlash between the external teeth of the rotating body and the first gear during rotation. That is, the embodiments of the present disclosure eliminate backlash between the external teeth of the rotating body and the first gear so that the first gear contacts the external teeth of the rotating body in substantially the same manner even if the rotating body repeatedly stops at a predetermined rotational angular position.

[0061] Therefore, a rotating body drive device according to an embodiment of the present disclosure is, in a broad sense, a rotating body drive device having a rotating body with external teeth, a drive gear that meshes with the external teeth of the rotating body and rotates around a rotation center line parallel to the rotation center line of the rotating body, and a position detection unit that detects the rotational angle position of the rotating body, wherein the position detection unit includes a base member, a rotating member supported on the base member so as to be rotatable around a first rotation center line parallel to the rotation center line of the rotating body, a first gear supported on the rotating member so as to be rotatable around a second rotation center line parallel to the first rotation center line and that meshes with the external teeth of the rotating body, and a sensor provided on the rotating member for detecting the rotational angle position of the first gear.

[0062] In addition, a position sensor unit according to another embodiment of the present disclosure is, in a broad sense, a position sensor unit that detects the rotational angle position of a rotating body having external teeth, and includes: a base member; a rotating member supported on the base member so as to be rotatable about a first rotational center line parallel to the rotational center line of the rotating body; a first gear supported on the rotating member so as to be rotatable about a second rotational center line parallel to the first rotational center line, and meshing with the external teeth of the rotating body; and a sensor provided on the rotating member for detecting the rotational angle position of the first gear.

[0063] As described above, the above-described embodiments have been described as examples of the technology of the present disclosure. For this purpose, drawings and detailed descriptions are provided. Therefore, the components described in the drawings and detailed descriptions may include not only components essential for solving the problem, but also components that are not essential for solving the problem in order to exemplify the above-described technology. Therefore, the fact that these non-essential components are described in the drawings or detailed descriptions should not be interpreted as immediately indicating that these non-essential components are essential.

[0064] Furthermore, since the above-described embodiments are intended to illustrate the technology of the present disclosure, various modifications, substitutions, additions, omissions, etc. can be made within the scope of the claims or their equivalents.

[0065] The present disclosure is applicable to devices that rotate rotating bodies.

Claims

1. a rotor having external teeth; a drive gear that meshes with the external teeth of the rotor and rotates about a rotation center line that is parallel to the rotation center line of the rotor; a position detection unit for detecting a rotational angle position of the rotating body, The position detection unit Base member, a rotating member supported by the base member so as to be rotatable about a first rotation center line parallel to the rotation center line of the rotating body; a first gear supported by the rotating member so as to be rotatable about a second rotation center line parallel to the first rotation center line, and meshing with external teeth of the rotating body; and a sensor provided on the rotating member for detecting a rotational angle position of the first gear;

2. A rotor having external teeth; a drive gear that rotates while meshing with the external teeth of the rotor; a position detection unit for detecting a rotational angle position of the rotating body, The position detection unit A base member; a rotating member supported by the base member so as to be rotatable about a rotation center line of the rotating body; a first gear rotatably supported by the rotary member and meshing with external teeth of the rotor; a sensor provided on the rotating member for detecting a rotational angle position of the first gear; a second gear axially connected to the first gear; a third gear rotatably supported by the rotary member, meshing with the second gear, and having a rotation angle detected by the sensor; a shaft that connects the first gear and the second gear in the axial direction; a cylindrical bearing that rotatably supports the shaft, Rotating body drive device.

3. The inner surface of the bearing is provided with a protrusion that contacts the shaft and shifts the shaft toward the third gear. The rotary body driving device according to claim 2 .

4. the position detection unit further includes a biasing member that biases the rotating member so that the first gear continues to contact the rotating body. The rotating body driving device according to claim 1 or 2.

5. a motor that rotates the drive gear; and a controller that feedback controls the motor based on the detection result of the sensor. The rotating body driving device according to claim 1 or 2.

6. the drive gear and the motor are supported on the base member of the position detection unit; The rotating body driving device according to claim 5 .

7. When viewed in the direction in which the rotation center line of the rotating body extends, a first straight line connecting the first rotation center line and the second rotation center line and a second straight line connecting the second rotation center line and the rotation center line of the rotating body are perpendicular to each other. The rotating body driving device according to claim 1 .

8. The position detection unit a second gear axially connected to the first gear; a third gear supported by the rotary member so as to be rotatable about a third rotation center line parallel to the first and second rotation center lines, meshing with the second gear, and having a rotation angle detected by the sensor; The rotating body driving device according to claim 1 .

9. The position detection unit a shaft that connects the first gear and the second gear in the axial direction; and Further comprising a cylindrical bearing that rotatably supports the shaft, A protrusion is provided on the inner surface of the bearing to contact the shaft and shift the shaft toward the third gear. The rotating body driving device according to claim 8 .

10. the rotating body is a cylindrical cam that is provided in a lens barrel and moves a lens in the lens barrel in the optical axis direction; The rotating body driving device according to claim 1 or 2.

11. A lens driving device comprising a rotating body driving device described in any one of claims 1 to 10.

12. A projector equipped with the lens driving device described in claim 11.

13. A position sensor unit for detecting a rotational angle position of a rotating body having external teeth, A base member; a rotating member supported by the base member so as to be rotatable about a first rotation center line parallel to the rotation center line of the rotating body; a first gear supported by the rotating member so as to be rotatable about a second rotation center line parallel to the first rotation center line, and meshing with external teeth of the rotating body; a position sensor unit provided on the rotating member for detecting a rotational angle position of the first gear.