JP5745351B2 - Drive transmission mechanism and lens holder - Google Patents

Description

  The present invention relates to a drive transmission mechanism and a lens holder having a drive transmission mechanism.

  Patent Document 1 discloses a drive transmission mechanism that can prevent damage to a gear due to an impact without increasing the hardness of the gear material when an external force due to the impact is applied, and an optical apparatus having the drive transmission mechanism. It is described that an interchangeable lens and a photographing apparatus are provided. Therefore, Patent Document 1 discloses a first holding structure that holds the first gear, the second gear that transmits the driving force to the first gear, and the first end of the second gear shaft of the second gear. And a second holding structure that holds the second end of the gear shaft so as to be movable in the axial direction of the second gear shaft, wherein the first holding structure is the first of the second gear shaft. The end is held using a recess whose sectional area gradually decreases as it moves away from the second gear shaft in the axial direction of the second gear shaft, and the second holding structure biases the second gear shaft in the direction of the first end. It is described to have a configuration having an elastic member.

JP 2005-352331 A

  In a zoom lens system that performs zooming by driving a lens holder that holds a plurality of lenses or a plurality of lens groups by a drive transmission mechanism equipped with a gear, in an imaging device equipped with such a zoom lens system, a drop, etc. There is a possibility that the gear may be damaged by applying an external force to the drive transmission mechanism in response to the impact.

  One aspect of the present invention includes a first member having a large-diameter first gear portion and a second shaft parallel to the first shaft of the first gear portion, and having a small diameter and a second diameter. A second gear which is long in one axial direction and meshes with the first gear portion on one end side and meshes on the other end side of the second gear and drives the first member via the second gear. 3 and one end of the second shaft, when a force is applied to the second gear from the first gear portion, the second shaft is inclined and one end portion is outside the first gear portion. A drive transmission mechanism having a bearing that is supported so as to be disengaged.

  Therefore, in this drive transmission mechanism, even if the first member is moved by the external force and the first gear portion having the large diameter is rotated, the external force is transmitted to the second gear having the small diameter via the first gear portion. That can be suppressed, and the possibility that the second gear and the third gear are damaged can be reduced.

  The drive transmission mechanism preferably includes an elastic member that pressurizes one end portion in the direction of the first gear portion when the one end portion of the second shaft is inclined. From the first state, the second gear can be returned to a state where the second gear meshes with the first gear portion.

  The drive transmission mechanism preferably includes a stopper that restricts the movement of the elastic member so that the second shaft is separated from the elastic member when the second gear is in the second state where the second gear is engaged with the first gear portion. It is possible to avoid the elastic member from becoming mechanical resistance (frictional force).

  The bearing preferably includes a hole into which one end of the second shaft is inserted, and the hole is preferably wider on the outside than on the inside. When the second shaft is tilted and is disengaged from the first gear portion, the hole portion is unlikely to become resistance, and when the second shaft returns from the outside to the inside, the hole portion is likely to be a guide. The hole is preferably substantially triangular or substantially fan-shaped.

  One of the different aspects of the present invention is a lens holder having the drive transmission mechanism described above, wherein the first member includes a cam cylinder that moves the lens frame in the direction of the first axis, and the first gear. The part is a lens holder that moves in the direction of the first axis while in contact with the second gear. One of the different aspects of the present invention is a zoom lens system having the above-described lens holder and at least one lens held in a lens frame of the lens holder. One of the different aspects of the present invention is an imaging apparatus having the zoom lens system described above and an imaging unit that acquires an image formed by the zoom lens system.

The figure which shows the outline | summary of the imaging device carrying the lens holder which has a drive transmission mechanism. The perspective view which expand | deploys and shows schematic structure of the zoom lens system containing a lens holder. The figure which looked at the zoom lens system containing a lens holder from the object side. Sectional drawing which looked at the periphery of the drive transmission mechanism in a normal state from the object side. Sectional drawing which shows the drive transmission mechanism in a normal state. FIGS. 6A and 6B are views of the drive transmission mechanism in a normal state as viewed from the object side, in which FIG. 6A is a view showing a leaf spring attached, and FIG. FIGS. 7A and 7B are views of the drive transmission mechanism in the retracted state as viewed from the object side, in which FIG. 7A shows a leaf spring attached and FIG. 7B shows a leaf spring removed. Sectional drawing which shows the drive transmission mechanism in a retracted state.

  FIG. 1 shows an outline of an imaging apparatus equipped with a zoom lens system including a drive transmission mechanism according to the present invention. The imaging apparatus 200 includes a zoom lens system 100 and a housing (body) 99 to which the zoom lens system 100 is attached. An example of the imaging device 200 is a camera.

  The zoom lens system 100 includes a lens holder (lens barrel) 1 having a plurality of tubes that move forward and backward (in and out) in the direction of the optical axis 101 with respect to a housing 99, and a first lens group 111 held by the lens holder 1. And the second lens group 112. The lens holder 1 includes a first lens frame 151 that holds the first lens group 111, a rectilinear guide cylinder (cylinder) 85 that holds the first lens frame 151, and the cylinder 85 in the direction of the optical axis 101. A cam cylinder (first member) 80 to be moved, a cylindrical portion (fixed cylinder) 11 that holds the cam cylinder 80 movably in the direction of the optical axis 101, a base 10 that holds the fixed cylinder 11, and a motor (drive) And a drive transmission mechanism 5 that transmits the driving force from the source 90 to the cam cylinder 80 via the train wheel 20 and rotationally drives the cam cylinder 80.

  The zoom lens system 100 is a lens system capable of zooming by changing the distances of a plurality of lenses included in the first and second lens groups 111 to 112. In the imaging state, the lens holder 1 is positioned in front of the housing 99 (on the object side). The lens holder 1 is housed in the housing 99 in the non-imaging state (collapsed state, parked state).

  The camera 200 is further focused by an IR cut filter 91 that is housed inside the housing 99 and transmits visible light and blocks near-infrared light, and the first and second lens groups 111 to 112. An imaging unit (imaging device, image sensor) 92 such as a CCD or CMOS that images light and converts it into an electrical signal (image data), and first and second lens groups 111 to 112 for zooming or focusing. A control unit 93 that moves in the direction of the axis 101, an LCD 94 that displays image data as an image, and a flash memory 95 that records image data are provided.

  FIG. 2 shows a zoom lens system 100 including the lens holder 1. In FIG. 2, the main parts constituting the lens holder 1 are shown expanded. The cam cylinder 80 as the first member is driven to rotate, so that the cylinder 85 and the cam cylinder 80 are accommodated in the fixed cylinder 11 (collapsed state, park state), and the cylinder 85 and the cam cylinder 80 are It includes a function of displacing to a state (imaging state) extended from the fixed cylinder 11. Furthermore, the cam cylinder 80 includes a function of controlling the position of the first lens frame 151 by moving the cylinder 85 in the direction of the optical axis 101 with respect to the cam cylinder 80 by being driven to rotate.

  The cam cylinder (first member) 80 includes a cam gear 81 which is a first gear portion provided at the end (rear end) of the rear (image side) 101b of the outer peripheral surface 80a, and a convex helicoid 82. ing. The fixed cylinder 11 that holds the cam cylinder 80 is provided on a part of the inner peripheral surface 11b, and has a concave helicoid 13 that spirally extends from the rear 101b toward the front 101a, and a front 101a rather than the concave helicoid 13. A circumferential groove 14 connected to the concave helicoid 13 and extending in the circumferential direction 102 and a straight guide groove (not shown) extending in the direction of the optical axis 101 at a pitch of 120 degrees in the circumferential direction 102 are provided. The cam cylinder 80 is accommodated in the fixed cylinder 11 so that the convex helicoid 82 meshes with the concave helicoid 13.

  The cam cylinder 80 is housed inside the fixed cylinder 11 in the retracted state. When the driving force from the motor 90 is transmitted to the cam cylinder 80 via the train wheel 20 including a plurality of gears, the cam cylinder 80 rotates and the convex helicoid 82 is guided by the concave helicoid 13 of the fixed cylinder 11 so that the optical axis. Move forward in direction 101. When the cam cylinder 80 further rotates, the convex helicoid 82 moves from the concave helicoid 13 to the circumferential groove 14. In the range in which the convex helicoid 82 of the cam cylinder 80 moves in the circumferential groove 14, the cam cylinder 80 does not move back and forth in the direction of the optical axis 101, but the rectilinear guide cylinder with respect to the cam cylinder 80 as the cam cylinder 80 rotates. 85 moves in the direction of the optical axis 101.

  The rectilinear guide cylinder 85 held by the cam cylinder 80 includes cam pins 86 provided at a 120-degree pitch in the circumferential direction 102 of the outer peripheral surface 85a. The cam pin 86 engages with a cam groove (not shown) provided on the inner peripheral surface 80b of the cam cylinder 80, and the position of the rectilinear guide cylinder 85 relative to the cam cylinder 80 when the cam cylinder 80 rotates, that is, the first lens. The positions of the frame 151 and the first lens group 111 are controlled.

  FIG. 3 shows a zoom lens system 100 including the lens holder 1 as viewed from the object side 101a. FIG. 4 is a sectional view of the drive transmission mechanism 5 and the train wheel 20 extracted from the lens holder 1 and viewed from the object side 101a. The drive transmission mechanism 5 of this example rotates the cam cylinder 80 by transmitting the driving force from the motor 90 to the cam cylinder 80 via the wheel train 20. The train wheel 20 is a second gear that meshes with the first gear portion (cam gear) 81 of the cam cylinder (first member) 80 in order from the driven side (output side) to the drive source side (input side). (Output gear, pinion gear) 22, third gear 23 that meshes with pinion gear 22, and fourth to seventh gears 24 to 27 that transmit driving force from motor 90 to third gear 23. For this reason, the driving force from the motor 90 is from the seventh gear 27 to the sixth gear 26, the fifth gear 25, the fourth gear 24, the third gear 23 and the pinion gear which is the output gear. The signal is transmitted to the cam gear 81 via the (second gear) 22.

  FIG. 5 is a sectional view of the drive transmission mechanism 5 extracted from the lens holder 1. The drive transmission mechanism 5 of this example includes a cam cylinder 80 provided with a large-diameter cam gear 81, a pinion gear 22 having a smaller diameter than the cam gear 81 and longer in the direction of the optical axis 101 than the cam gear 81, and a cam cylinder 80 via the pinion gear 22. And a third gear 23 for driving the motor.

  The pinion gear (second gear) 22 rotates about a second shaft (gear shaft) 30 parallel to the optical axis 101 that is the first shaft of the cam gear (first gear portion) 81 and the gear shaft 30. A plurality of gear teeth 40. The pinion gear 22 meshes with the cam gear 81 on one end side (object side) 101a, and meshes with the third gear 23 on the other end side (image side) 101b. In the pinion gear 22, the gear shaft 30 and the plurality of gear teeth 40 may be separate, or the gear shaft 30 and the plurality of gear teeth 40 may be formed integrally.

  The cam gear 81, the pinion gear 22 and the third gear 23 are all flat teeth, and each of the plurality of gear teeth 40 of the pinion gear 22 meshing with the cam gear 81 and the third gear 23 has a tooth width w of the light of the cam cylinder 80. It is formed to be longer than the moving distance (stroke) in the direction of the axis 101. Therefore, the driving force of the motor 90 can be transmitted to the cam cylinder 80 from the retracted state P1 to the imaging state P2, and the cam gear 81 moves along the pinion gear 22 so as to slide in the direction of the optical axis 101. .

  The lens holder 1 includes a first bearing 51 that supports one end 31 of the gear shaft 30 of the pinion gear 22 and a second bearing 52 that supports the other end 32 of the gear shaft 30. The 1st bearing 51 and the 2nd bearing 52 are formed so that a part of outer peripheral surface 11a of the fixed cylinder 11 may protrude. The first bearing 51 includes a hole 51 a into which one end 31 of the gear shaft 30 is inserted. The hole 51 a is wider on the outer side 110 than on the inner side 120. The pinion gear 22 has one end 31 of the gear shaft 30 inserted into the hole 51 a of the first bearing 51 and the other end 32 fitted into the recess 52 a of the second bearing 52, so that the gear shaft 30 moves in the direction of the optical axis 101. It is held by the fixed cylinder 11 in a state of being arranged in parallel.

  Since the driven cam gear 81 and the third to seventh gears 23 to 27 on the driving source side are connected so that power is transmitted through the pinion gear 22, the cam gear 81 on the driven side is in the reverse direction. There is a possibility that power will be transmitted to. For example, when an external force such as a drop impact is applied to the lens holder 1 in the imaging state P <b> 2 in which the cam cylinder 80 is extended from the fixed cylinder 11, the external force tries to rotate the cam cylinder 80 in any one of the circumferential directions 102. It is converted into a rotating force. Therefore, when this rotational force is transmitted to the third to seventh gears 23 to 27 via the cam gear 81 and the pinion gear 22 of the cam cylinder 80, tooth loss or damage is caused in the train wheel 20 including the pinion gear 22. There is a risk of causing.

  The drive transmission mechanism 5 of this example supports the pinion gear 22 so that when the force is applied from the cam gear 81 to the pinion gear 22, the gear shaft 30 is inclined and one end (one end) 31 of the gear shaft 30 is detached from the cam gear 81 to the outside 110. A first bearing 51 is provided. For this reason, it can suppress that the force of the reverse direction from the cam gear 81 is transmitted to the wheel train 20 containing the 3rd gear 23 via the pinion gear 22. FIG.

  6 shows the drive transmission mechanism 5 extracted from the lens holder 1 and viewed from the object side 101a. FIG. 6 (a) is a view showing a leaf spring 71 attached, and FIG. 6 (b) is a leaf spring. It is a figure which removes 71 and shows it.

  As shown in FIGS. 5 and 6, in the lens holder 1 provided with the drive transmission mechanism 5, when an external force is applied to the pinion gear 22 through the cam gear 81 of the cam cylinder 80 due to an impact such as dropping, The pinion gear 22 can be retracted from the cam gear 81 by tilting the one end 31 of the gear shaft 30 to the outer side 110 with the recess 52a supporting the other end 32 of the gear shaft 30 as a fulcrum. That is, since the force acting in the radial direction between the cam gear 81 and the train wheel 20 is proportional to the torque of each gear, when the large-diameter cam gear 81 is driven by the small-diameter pinion gear 22, the torque is small, so the gear shaft 30. However, since the torque transmitted from the large-diameter cam gear 81 to the small-diameter pinion gear 22 is large, the gear shaft 30 can be tilted to remove the one end 31 from the cam gear 81 to the outside 110. Accordingly, it is possible to provide the lens holder 1 that can efficiently and easily release the engagement between the pinion gear 22 and the cam gear 81 regardless of the direction of the rotational force acting on the cam cylinder 80.

  In the lens holder 1 provided with the drive transmission mechanism 5, only the engagement between the pinion gear 22 and the cam gear 81 can be released while maintaining the engagement between the pinion gear 22 and the third gear 23, so that the pinion gear 22 does not rotate. Thus, transmission of force from the third gear 23 to the drive source side (upstream side) can be suppressed. For this reason, the pinion gear 22 and the cam gear 81 have a simple configuration in which one end 31 of the gear shaft 30 is inclined with the recess 52a as a fulcrum without retracting the plurality of gear teeth 40 of the pinion gear 22 over the entire tooth width w. The mesh can be released efficiently and easily. Therefore, in this lens holder 1, it is possible to suppress the transmission of an external force accompanying an impact such as a drop to the third to seventh gears 23 to 27 via the pinion gear 22, and the train wheel 20 including the pinion gear 22 and Tooth chipping and breakage of the cam gear 81 can also be suppressed. Furthermore, as shown in FIG. 6B, the hole 51 a of the first bearing 51 is formed in a substantially triangular shape or a substantially fan shape so that the outer side 110 is wider than the inner side 120. Is less likely to become resistance when it is tilted and disengages from the cam gear 81 to the outside 110.

  FIG. 7 shows the drive transmission mechanism 5 in the first state (retracted state) 61 in which the one end 31 of the gear shaft 30 is inclined as seen from the object side 101a. FIG. FIG. 7B is a diagram illustrating the attachment, and FIG. In FIG. 8, the drive transmission mechanism 5 in the retracted state 61 is extracted and shown in a sectional view.

  As shown in FIGS. 7A and 8, when the lens holder 1 is in the retracted state 61 in which the one end 31 of the gear shaft 30 is inclined to the outer side 110, the one end 31 faces the cam gear 81, that is, the inner side 120. An elastic member (leaf spring) 71 for pressurization is provided. One end 31 of the gear shaft 30 is disposed so as to protrude slightly from the first bearing 51 to the object side 101 a through the hole 51 a of the first bearing 51, and the leaf spring 71 is arranged in the first bearing 51. Are disposed along the object side 101a.

  In this lens holder 1, after tilting one end 31 of the gear shaft 30 to the outer side 110 with the concave portion 52 a as a fulcrum, the one end 31 of the gear shaft 30 is pushed back to the inner side 120 with the concave portion 52 a as a fulcrum by the elastic force of the leaf spring 71. be able to. Therefore, it is possible to quickly return from the retracted state 61 to the second state (normal state) 62 in which the pinion gear 22 engages with the cam gear 81. Further, as shown in FIG. 7B, the hole 51 a of the first bearing 51 is formed in a substantially triangular shape or a substantially fan shape so that the outer side 110 becomes wider with respect to the inner side 120. Tends to be a guide when returning from the outside 110 to the inside 120. An example of the elastic member 71 is a leaf spring, but it may be a coil spring or resin bending. The hole 51 a is not limited to a triangle or a fan shape, and may have a shape that expands from the inner side 120 toward the outer side 110.

  Further, the lens holder 1 has a stopper 72 that restricts the movement of the leaf spring 71 so that the gear shaft 30 is separated from the leaf spring 71 when the pinion gear 22 is in a normal state 62 where the pinion gear 22 is engaged with the cam gear 81. The stopper 72 includes a convex wall 72 a that stands on the object side 101 a along the peripheral edge 51 b of the hole 51 a of the first bearing 51. As shown in FIG. 6B, the convex wall 72 a is disposed so as to slightly protrude toward the outer side 110 from the position where the gear shaft 30 is disposed in the normal state 62. For this reason, in this lens holder 1, the plate spring 71 can be brought into a non-contact state with respect to the gear shaft 30 after the gear shaft 30 is returned from the retracted state 61 to the normal state 62. It can be avoided that the spring 71 becomes a mechanical resistance (frictional force) to the gear shaft 30. Accordingly, it is possible to prevent the leaf spring 71 from reducing the driving force transmitted from the pinion gear 22 to the cam gear 81 in the normal state 62.

  The zoom lens system 100 may include a third lens group, and is not limited to the second group. The imaging device 200 is not limited to a camera, and may be another optical device such as a handy projector. Further, the drive transmission mechanism 5 is suitable for driving the first member via a gear or a train wheel in a device including a first member that may receive an impact from the outside. is there.

DESCRIPTION OF SYMBOLS 1 Lens holder (lens barrel), 5 Drive transmission mechanism 100 Zoom lens system 200 Imaging device (camera)

Claims (8)

A first member having a first gear portion having a large diameter;
A second gear including a second shaft parallel to the first shaft of the first gear portion, having a small diameter and being long in the second axial direction and meshing with the first gear portion on one end side; ,
A third gear that meshes with the other end of the second gear and drives the first member via the second gear;
When one end portion of the second shaft is applied to the second gear from the first gear portion, the second shaft is inclined and the one end portion is separated from the first gear portion. A drive transmission mechanism having a bearing that is supported so as to be disengaged to the outside. In claim 1,
A drive transmission mechanism having an elastic member that pressurizes the one end portion in the direction of the first gear portion when the one end portion of the second shaft is in a tilted first state. In claim 2,
A drive transmission mechanism having a stopper for restricting movement of the elastic member so that the second shaft is separated from the elastic member when the second gear is in a second state where the second gear is engaged with the first gear portion. In any of claims 1 to 3,
The bearing includes a hole portion into which the one end portion of the second shaft is inserted, and the hole portion has a wider outside than the inside. In claim 4,
The hole is a drive transmission mechanism having a substantially triangular shape or a substantially fan shape. A lens holder having the drive transmission mechanism according to claim 1,
The first member includes a cam cylinder that moves the lens frame in the direction of the first axis;
The first gear portion is a lens holder that moves in the direction of a first axis while being in contact with the second gear. A lens holder according to claim 6;
A zoom lens system comprising: at least one lens held by the lens frame of the lens holder. A zoom lens system according to claim 7;
An imaging apparatus comprising: an imaging unit that acquires an image formed by the zoom lens system.

Images