Driving device and lens barrel having the same

Abstract

To provide a driving device capable of holding a lens frame when a voice coil motor is not energized without using complex structures and capable of driving accurately a heavier lens frame at high speed while reducing backlash compared to driving by stepping motor alone, and a lens barrel having the same.SOLUTION: A disclosed driving device includes: a lens frame holding a lens group; a voice coil motor for moving the lens frame in an optical axis direction; and a stopper mechanism for regulating the lens frame from moving. The stopper mechanism includes the stepping motor and a lead screw that is driven by the stepping motor, and the lead screw is screwed into the lens frame.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a driving device and a lens barrel having the same, and more particularly to a method for driving a lens unit that can move back and forth along an optical axis. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in digital cameras and digital video cameras, a stepping motor or a voice coil motor is used as a drive device for moving a lens frame in the optical axis direction for zooming and focusing.

[0003] Driving the lens frame with a stepping motor allows for high-speed and accurate positioning, but has the drawback of being unable to drive the heavy lens frame at high speed due to its small torque.

[0004] On the other hand, a voice coil motor has a higher torque than a stepping motor, so it can drive a heavy lens frame at high speed. However, since it does not have a stable stopping position when de-energized, it has the disadvantage that the lens frame driven by the voice coil motor will not be held within its movable range when de-energized and will move. This can cause abnormal noise due to collisions inside the lens barrel.

[0005] Patent Document 1 discloses a lens driving device having a lead screw that is compact, has a small number of parts, efficiently prevents backlash, and is capable of driving with high precision.

[0006] Furthermore, Patent Document 2 discloses a lens barrel and a camera device that can prevent movement of an optical element inside the lens barrel even when the voice coil motor is not energized. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-215309 [Patent Document 2] Japanese Patent Application Publication No. 2019-109427 Summary of the Invention [Problem to be solved by the invention]

[0008] In the lens driving device described in Patent Document 1, the weight of the lens frame that can be stably driven is limited by the load of the biasing spring used to reduce the rattle of the connecting parts.

[0009] The lens barrel described in Patent Document 2 requires a drive mechanism to move the stopper member, which holds the movable lens frame when the voice coil motor is not energized, from a retracted position to an abutting position, which increases the number of parts and complicates the structure.

[0010] The present invention has been made in consideration of the above circumstances, and aims to provide a drive device and a lens barrel having the same that can hold a lens frame when the voice coil motor is not energized without using a complex structure, and that can drive a heavier lens frame at high speed with precision while reducing backlash compared to driving using a stepping motor alone. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems, a drive device according to a first aspect of the present invention comprises: a lens frame that holds a lens group; a voice coil motor that moves the lens frame in the optical axis direction; A stopper mechanism that restricts the movement of the lens frame is provided. The stopper mechanism is A stepping motor; a lead screw rotated by a stepping motor; The lead screw is screwed into the lens frame. The lens frame is driven by a stepping motor to move in the direction of the optical axis. It is characterized by:

[0012] A drive device according to a second aspect of the present invention is a lens frame that holds a lens group; a voice coil motor that moves the lens frame in the optical axis direction; a stopper mechanism that restricts movement of the lens frame body; The lens frame is It has a fixed portion, The stopper mechanism is A stepping motor; a lead screw rotated by the stepping motor; A stopper member is provided which is threadedly engaged with the lead screw and moves in the optical axis direction by the drive of the stepping motor. The lens frame and the lead screw are threadedly engaged by fixing the fixed portion and the stopper member.

[0013] A drive device according to a third aspect of the present invention is A direction control unit; A drive control unit is provided. The direction control unit is The voice coil motor controls the force that moves the lens frame forward and backward in the optical axis direction, The drive control unit The stopper mechanism is driven or stopped.

[0014] A lens barrel according to a fourth aspect of the present invention is characterized by including the drive device according to the third aspect of the present invention. [Effects of the Invention]

[0015] According to the present invention, it is possible to hold the lens frame when the voice coil motor is not energized, and it is possible to drive the heavier lens frame with high precision and at high speed compared to a drive system using only a stepping motor. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a lens barrel 20 equipped with a focus unit 22 according to an embodiment of the present invention attached to a camera body 10. [Figure 2] FIG. 1 is a side view of a focus unit 22 according to an embodiment of the present invention. [Figure 3] Cross-sectional view of Figure 2 cut at L, seen from the front [Figure 4] FIG. 10 is a schematic diagram illustrating the operation of moving the lens frame 30 by the voice coil motor 40 and the stepping motor 51 in the focus unit 22. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments. Also, the drawings are simplified to facilitate the explanation of the present invention.

[0018] FIG. 1 is a schematic diagram showing the configuration of a lens barrel equipped with a focus unit 22 according to an embodiment of the present invention attached to a camera body 10, FIG. 2 is a side view of the focus unit 22, FIG. 3 is a cross-sectional view taken along line L in FIG. 2 as viewed from the front, and FIG. 4 is a schematic diagram explaining the operation of moving a lens frame body 30 in the focus unit 22 using a voice coil motor 40 and a stepping motor 51.

[0019] 1, a camera control unit 11 included in a camera body 10 and a lens control unit 21 included in a lens barrel 20 communicate with each other. The camera control unit 11 and the lens control unit are configured with a processing device such as a CPU. The lens control unit 21 is configured to perform various controls within the lens barrel 20 in response to commands from the camera control unit 11 and commands from various switches arranged on the outer surface of the lens barrel (not shown). For example, when a release button (not shown) included in the camera body 10 is operated, the camera control unit 11 issues a focus drive instruction to the lens control unit 21 in response to the operation, and the lens control unit 21 issues an instruction to a focus control unit 60 in the focus unit 22 to control the drive of the focus unit 22.

[0020] Next, the configuration of the focus unit 22 will be described with reference to FIGS.

[0021] As shown in FIGS. 2 and 3, the focus unit 22 includes a lens frame 30, a voice coil motor 40, and a stopper mechanism 50.

[0022] The voice coil motor 40 includes a yoke a 41, a yoke b 42, an end yoke a 43, an end yoke b 44, a magnet 45, and a coil 46. The coil 46 has a winding shaft, and the yoke a 41 is inserted through the winding shaft.

[0023] The coil 46 is fixed to the lens frame 30 via a coil holder 47, and is configured so that when the coil 46 moves, the lens frame 30 moves integrally therewith.

[0024] The magnet 45 is fixed to the yoke b42, and is fixed to the surface of the yoke b42 that faces the yoke a41. The end yoke a43 and the end yoke b44 are arranged to fix the yoke a41 and the yoke b42 together.

[0025] The focus unit 22 may be configured to include multiple voice coil motors 40. For example, in addition to the voice coil motor 40, a voice coil motor of the same configuration may be placed at a position symmetrical with respect to the center of the lens frame 30. This makes it possible to obtain a large thrust force, and further makes it possible to prevent unnecessary moments from being generated when the lens frame 30 is moved in the optical axis direction.

[0026] The lens frame 30 holds a lens group 33, and has a fixed portion 31 through which guide bars 341 and 342 arranged parallel to the optical axis are inserted. The lens frame 30 is movable in the optical axis direction via the guide bars 341 and 342. While the lens group 33 is illustrated as a single lens by way of example, it may be a lens group including multiple lenses or a cemented lens in which multiple lenses are cemented together. In addition, it may include other optical elements such as an aperture or a filter.

[0027] 2 and 3, the fixed portion 31 is disposed so as to face the voice coil motor 40 with respect to the center of the lens frame 30, but this is not limitative.

[0028] The stopper mechanism 50 has a stepping motor 51, a lead screw 52, ​​and a stopper member 53. The lead screw 52 is fixed to the rotation shaft of the stepping motor 51, and the stopper member 53 is threadedly engaged with the lead screw 52. By driving the stepping motor 51, the lead screw 52 is rotated, and the stopper member 53 threadedly engaged with the lead screw 52 is configured to be movable in the optical axis direction.

[0029] The fixed portion 31 and the stopper member 53 are fixed with adhesive or screws to prevent gaps or backlash. By fixing the fixed portion 31 and the stopper member 53, the lens frame 30 can move in the optical axis direction by rotating the lead screw 52.

[0030] 2 and 3, the fixed portion 31 is configured as a protrusion provided on a part of the lens frame 30, but this is not limiting. The stopper member 53 may be fixed to any location on the lens frame 30, or a separate member that connects the lens frame 30 and the stopper member 53 may be prepared and fixed.

[0031] Alternatively, the lead screw 52 may be configured to be directly screwed into the lens frame 30 without passing through the fixed portion 31 and the stopper member 53. In the case where the lead screw 52 is configured to be directly screwed into the lens frame 30, the lead screw 52 is rotated by driving the stepping motor 51, and the lens frame 30 screwed into the lead screw 52 is configured to be movable in the optical axis direction.

[0032] Furthermore, the focus unit 22 includes a focus control section 60. The focus control section 60 controls the amount of current flowing to each motor included in the focus unit 22, the direction of the current, the timing of the current flow, and the like.

[0033] The focus control unit 60 includes a motor driver V61 which is a direction control unit and a motor driver S62 which is a drive control unit. The motor driver V61 controls the drive of the voice coil motor 40, and the motor driver S62 controls the drive of the stepping motor 51.

[0034] Next, the operation of each motor provided in the focus unit 22 will be described.

[0035] The voice coil motor 40 has an end of the coil 46 connected to a flexible printed circuit board 70 (not shown), and the flexible printed circuit board 70 is connected to a power supply unit 80 (not shown) via a motor driver V61. When a current is supplied from the power supply unit 80, a thrust force is generated in the optical axis direction.

[0036] The motor driver V61 receives instructions from the lens control unit 21 and controls the voice coil motor 40. For example, when receiving an instruction from the lens control unit 21 to move the coil 46 forward in the optical axis direction, the motor driver V61 generates a thrust in a direction to move the coil 46 forward in the optical axis direction, and when receiving an instruction to move the coil 46 backward, the motor driver V61 generates a thrust in a direction to move the coil 46 backward in the optical axis direction.

[0037] When the coil 46 is moved forward or backward in the optical axis direction, the direction can be controlled by controlling the direction of the current supplied to the coil 46 using the motor driver V61, thereby switching between the forward direction and the backward direction.

[0038] The stepping motor 51 is also connected to a flexible printed circuit board 70 (not shown), and the flexible printed circuit board 70 is connected to a power supply unit 80 (not shown) via a motor driver S62. When a current is supplied from the power supply unit 80, a lead screw 52 fixed to the output shaft of the stepping motor 51 rotates, and the rotation of the lead screw 52 moves a stopper member 53.

[0039] The motor driver S62 receives instructions from the lens control unit 21 and controls the stepping motor 51. For example, when an instruction to move the lens frame 30 to a desired position is received from the lens control unit 21, the stepping motor 51 is driven to rotate the lead screw 52 and move the stopper member 53 to the desired position.

[0040] To move to a desired position with greater precision, the focus unit 22 may be configured to include a position detection sensor. The position detection sensor may be, for example, a magnetic sensor such as a magnetoresistive element or a Hall element, or a position detection sensor such as an optical encoder using a photosensor, thereby realizing a configuration that accurately detects the amount of movement of the lens frame 30.

[0041] Next, we will explain how the lens frame 30 is held when not energized. The lens frame 30 is fixed to the coil 46 of the voice coil motor 40 via the coil holding portion 47, and is therefore movable within a range until the coil 46 abuts against the end yoke a 43 and the end yoke b 44.

[0042] 2, the fixed portion 31 of the lens frame 30 is fixed to a stopper member 53 of the stopper mechanism 50. The stopper member 53 moves on a lead screw 52 when the stepping motor 51 is driven, but does not move when not energized and is fixed on the lead screw 52. As a result, the lens frame 30 fixed to the voice coil motor 40 is held by the stopper member 53 when not energized.

[0043] Next, the operation of the lens frame 30 in the focus unit 22 will be described.

[0044] When the focus control unit 60 receives a focus drive command from the lens control unit 21, the motor driver V61 and motor driver S62 provided in the focus control unit 60 control the voice coil motor 40 and stepping motor 51 to move the lens frame body 30 provided in the focus unit 22 back and forth in the optical axis direction.

[0045] The motor driver V61 controls the voice coil motor 40 to switch between driving the lens frame 30 forward or backward along the optical axis direction. The voice coil motor 40 controlled by the motor driver V61 generates a thrust force greater than or equal to the load of the lens frame 30.

[0046] With the voice coil motor 40 generating thrust, the motor driver S62 controls the stepping motor 51 to move the lens frame 30 to a desired position, thereby rotating the lead screw 52 and moving the stopper member 53 to the desired position. Because the voice coil motor 40 generates thrust in the direction of the desired position, the lens frame 30 moves to the desired position as the stopper member 53 moves.

[0047] Normally, when a stepping motor is subjected to a load, the rotation speed of the motor decreases, and the movement speed of the nut member that moves on the lead screw also decreases. By configuring the focus unit 22 as in this embodiment, the thrust generated by the voice coil motor 40 is used to bear the load of the lens frame 30 that is applied to the stepping motor 51, making it possible to move the stopper member 53 at high speed. As a result, by moving the stopper member 53 while the voice coil motor 40 is providing the thrust to move the lens frame 30, it is possible to move the heavier lens frame 30 at high speed with greater precision than if the lens frame 30 were moved by driving the stepping motor 51 alone.

[0048] Furthermore, the voice coil motor 40 continues to generate thrust in the direction before switching until it receives a command from motor driver V61 to switch the drive direction. When the lens frame 30 reaches the desired position, motor driver S62 controls the stepping motor 51 to stop the rotation of the lead screw 52. When the rotation of the lead screw 52 stops, the lens frame 30 stops at the desired position. Although the voice coil motor 40 continues to generate thrust, the lens frame 30 will not move unless the lead screw 52 rotates. Furthermore, because the voice coil motor 40 continues to generate thrust in one direction, the biasing force in one direction can eliminate backlash at the threaded portion between the lead screw 52 and the lens frame 30.

[0049] 4, the focus control unit 60 causes the motor driver V61 to generate a thrust in the voice coil motor 40 in the direction of position X, and the motor driver S62 controls the stepping motor 51 to move the stopper member 53 to position X. The lens frame 30 moves to position X by the thrust of the voice coil motor 40 and the position control of the stepping motor 51.

[0050] In this embodiment, the drive unit is configured to move the lens frame in the optical axis direction for focusing, but the present invention is not limited to this. For example, the drive unit may be configured to move the lens frame in the optical axis direction for zooming.

[0051] In addition, in this embodiment, only the main parts of the present invention have been described, and other parts can be configured using known techniques related to appropriate drive devices and lens barrels.

[0052] As explained above, the drive device described in the present invention makes it possible to hold the lens frame body, which is moved by the voice coil motor, even when power is not applied, and makes it possible to drive the heavier lens frame body with high precision and speed compared to a drive system using a stepping motor alone. [Explanation of symbols]

[0053] 10 Camera body 11 Camera control unit 20 Lens barrel 21 Lens control unit 22 Focus Unit 30 Lens frame 31 Fixed part 33 Lens Group 341 Guide Bar 342 Guide Bar 40 Voice coil motor 41 York A 42 York B 43 End yoke a 44 End yoke b 45 Magnet 46 Coil 47 Coil holding part 50 Stopper mechanism 51 Stepping motor 52 lead screw 53 Stopper member 60 Focus control section 61 Motor Driver V 62 Motor Driver S

Claims

1. a lens frame that holds a lens group; a voice coil motor that moves the lens frame in the optical axis direction; a stopper mechanism that restricts movement of the lens frame body; The stopper mechanism includes: A stepping motor; a lead screw rotated by the stepping motor; The drive device is characterized in that the lead screw is threadedly engaged with the lens frame, and the lens frame is moved in the optical axis direction by driving the stepping motor.

2. A lens frame that holds a lens group; a voice coil motor that moves the lens frame in the optical axis direction; a stopper mechanism that restricts movement of the lens frame body; The lens frame body is It has a fixed portion, The stopper mechanism includes: A stepping motor; a lead screw rotated by the stepping motor; a stopper member that is threadedly engaged with the lead screw and moves in the optical axis direction by being driven by the stepping motor; The drive device is characterized in that the lens frame and the lead screw are threadedly engaged by fixing the fixed portion and the stopper member.

3. A direction control unit; A drive control unit is provided. The direction control unit the voice coil motor controls the force that moves the lens frame body back and forth in the optical axis direction; The drive control unit 3. The drive device according to claim 1, wherein the stopper mechanism is driven or stopped.

4. A lens barrel comprising the drive device according to claim 3.

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