JP2007034070A - Lens driving unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the damage of a lens driving unity even when the lens driving unit receives impact force such as drop. <P>SOLUTION: The lens driving unit is equipped with: a lens frame 20 supported to freely move back and forth in an optical axis direction; a cam ring 40 performing cam action to move the lens frame in the optical axis direction; and a driving mechanism driving the cam ring 40, and includes: a driving ring 30 having a driving piece 32 and supported to freely move back and forth; an engaging piece 43 formed on the cam ring 40 so as to be engaged with the driving piece 32 by the movement of the cam ring 40 in one direction and separated from the driving piece 32 by the movement thereof in the other direction; and a spring 90 energizing the cam ring 40 in one direction so as to engage the engaging piece 43 with the driving piece 32 as the driving mechanism. The driving mechanism is formed so that the engaging piece 43 is separated from the driving piece 32 when external force is transmitted from the lens frame 20 to the cam ring 40. Thus, a situation that driving force is reversely transmitted from the cam ring 40 to the driving ring 30 is surely prevented, and mechanical damage or the like is prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens driving device applied to a digital camera mounted on a mobile phone, a portable personal computer or the like, and more particularly to a lens driving device provided with a driving mechanism capable of absorbing an impact force caused by dropping or the like.

  As a conventional lens driving device, a cylindrical fixed cylinder fixed to a base, a cylindrical cam cylinder rotatably arranged inside the fixed cylinder, and a reciprocating arrangement in the optical axis direction inside the cam cylinder A plurality of lens frames that hold the lens, a coil spring that is disposed between the lens frames and extends and contracts in the optical axis direction, a spur gear train that drives the cam cylinder, and a drive mechanism that includes a drive motor. When the cam cylinder is rotated by the rotation, the cam groove exerts a cam action on the follower pin of the lens frame to move the lens frame in the optical axis direction. There is known one that is configured to contract to absorb impact force (see, for example, Patent Document 1).

JP-A-8-110454

By the way, when the conventional lens driving device receives an impact force from the outside, the lens frame at the front end is retracted (retracted) and at the same time, the coil spring is contracted to reduce the impact force, and the follower pin falls off from the cam groove. In other words, it is basically intended to maintain the engaged state between the follower pin and the cam groove. Therefore, when an excessive impact force is applied, the follower pin may fall out of the cam groove and not perform the intended function.
In addition, when using a worm gear and worm wheel as a drive mechanism, the reverse drive force from the worm wheel to the worm gear is functionally impossible to transmit, so the lens frame retraction operation itself becomes impossible. There is a risk that the follower pin will not fall off but the gear may be damaged.

  The present invention has been made in view of the above circumstances. The purpose of the present invention is to absorb or release the impact force surely even if it receives an impact force (external force) due to dropping or the like, It is an object of the present invention to provide a small and thin lens driving device that can prevent damage to the mechanism and can be mounted on a small portable information terminal such as a mobile phone or a portable personal computer.

The lens driving device of the present invention includes a lens frame that holds a lens and is supported so as to be reciprocable in the optical axis direction, a cam member that exerts a cam action for moving the lens frame in the optical axis direction, and a drive that drives the cam member. A driving member that has a driving piece and is supported so as to be reciprocally movable; and a cam member that engages the driving piece in one direction; and An engaging piece formed on the cam member so as to be disengaged from the driving piece by movement in the other direction, and a spring for biasing the cam member in one direction so as to engage the engaging piece with the driving piece. When the external force is transmitted from the lens frame to the cam member, the engaging piece is formed so as to be detached from the driving piece.
According to this configuration, in a normal operation, when the driving member is operated and the driving piece applies a driving force to the engaging piece, the cam member is operated to exert a cam action on the lens frame. Move in the axial direction. Thereby, zooming or focusing is performed.
Here, when an external force (impact force) is received by dropping or the like and the external force is transmitted from the lens frame to the cam member, the engagement piece separates from the drive piece against the biasing force of the spring. Therefore, it is possible to reliably prevent the driving force from being transmitted from the cam member to the driving member in the reverse direction, and the spring is elastically deformed to relieve the impact force, thereby preventing the mechanism from being damaged.

In the above configuration, the lens frame has a follower, the cam member has a cam portion that engages the follower and exerts a cam action, and a spring that biases the follower toward the cam portion is provided. be able to.
According to this configuration, when an external force (impact force) such that the lens frame pops out (draws out) is received, the lens frame tries to jump out against the biasing force of the spring that biases the follower toward the cam portion. Therefore, the spring is elastically deformed and the impact force is relaxed, so that the mechanism can be prevented from being damaged.

In the above configuration, the drive member is an annular drive ring that is rotatably supported around the optical axis, and the cam member is rotatably supported around the optical axis and is cammed on the front end surface in the optical axis direction. The drive mechanism includes a drive motor and a worm gear directly connected to the drive motor, and the drive ring has a worm wheel that meshes with the worm gear at a part of the outer periphery thereof. be able to.
According to this configuration, in a normal operation, when the drive motor is activated, the worm gear rotates to rotate the worm wheel and the drive ring. Then, the cam ring rotates through the engagement between the drive piece and the engagement piece, the cam portion exerts a cam action on the follower, and the lens frame moves in the optical axis direction.
Here, when an external force (impact force) due to dropping or the like is received and the lens frame moves in the retracting direction, the follower presses the cam portion to rotate the cam member, and the engaging piece is detached from the driving piece. Therefore, the drive ring remains stopped without rotating. Thereby, it is possible to prevent the driving force from being transmitted in the reverse direction from the worm wheel to the worm gear, and it is possible to prevent the gear from being damaged.

In the above configuration, the drive ring and the cam ring are arranged adjacent to each other in the optical axis direction, the drive piece is formed to protrude from the outer periphery of the drive ring and extend in the optical axis direction, and the engagement piece is formed of the cam ring. The structure which protrudes from the outer periphery and can be employ | adopted.
According to this configuration, it is possible to easily form a mechanism that absorbs or relaxes an external impact force or the like while achieving thinning and simplification of the structure in the optical axis direction.

  The lens drive device with the above configuration achieves miniaturization and thinning, and even if it receives impact force (external force) due to dropping, it can absorb or release the impact force to prevent damage to the mechanism. Therefore, the present invention can be easily applied to small portable information terminals such as mobile phones and portable personal computers.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.
1 to 4 show an embodiment of a lens driving device according to the present invention. FIG. 1 is an exploded perspective view of the device, FIG. 2 is a front view of the device, and FIGS. 3 and 4 are side views of the device. FIG.

As shown in FIGS. 1 to 4, the lens driving device includes a base 10 having a cylindrical portion 11 extending in the optical axis direction L, a lens frame 20 accommodated in the cylindrical portion 11, and an outer periphery of the cylindrical portion 11. Driving force is applied to an annular driving ring 30 as a driving member provided to be rotatable with respect to the surface, an annular cam ring 40 as a cam member, a seating surface ring 50, a compression spring 60, a presser ring 70, and the driving ring 30. A step motor 80 as a drive motor to be applied, a coil spring 90 that urges the cam ring 40 to rotate clockwise, a detection sensor 100 that detects the position of the cam ring 40, and the like are provided.
A drive mechanism that rotationally drives the cam ring 40 is configured by the step motor 80, a worm gear 81 that will be directly connected to the step motor 80, a drive ring 30, a worm wheel 33 of the drive ring 30 that will be described later, and the like.

  As shown in FIGS. 1 to 4, the base 10 supports a cylindrical portion 11 having an axis in the optical axis direction L, a fixing portion 12 for fixing the step motor 80, and a drive ring 30 slidably in the thrust direction. A seating surface 13, a latching pin 14 for latching the end of the coil spring 90, and the like are provided. A recess (not shown) for receiving and fixing an imaging element such as a CCD is formed behind the cylindrical portion 11.

  The cylindrical portion 11 has a cylindrical shape, and is formed by three guide holes 11 a that penetrate in the radial direction and extend in the optical axis direction L and open to the front side F. The three guide holes 11a are formed at equiangular intervals (120 degrees) in the circumferential direction.

As shown in FIGS. 1 and 2, the lens frame 20 is formed by a cylindrical portion 21 that holds the lens G therein, three followers 22 that protrude radially outward from the outer peripheral surface of the cylindrical portion 21, and the like. In front of the lens G, an aperture plate 23 having a predetermined aperture is provided.
As shown in FIGS. 1 and 2, the cylindrical portion 21 is fitted (internally fitted) on the inner peripheral surface of the cylindrical portion 11 and is supported so as to be slidable in the optical axis direction L.

  The three followers 22 are formed at equal angular intervals (120 degrees) in the circumferential direction, are inserted into the guide holes 11a of the cylindrical portion 11, and are reciprocated only in the optical axis direction L without rattling in the circumferential direction. Guided freely. Further, the follower 22 has a rear side R side surface engaged with a cam surface 42 of a cam ring 40 described later, and a front side F side surface is engaged with an end portion of the compression spring 60 via a seating surface ring 50. It is like that.

As shown in FIGS. 1 to 4, the drive ring 30 has an annular portion 31 fitted on the cylindrical portion 11, projects radially outward from the outer peripheral surface of the annular portion 31, and extends forward F in the optical axis direction L. The pin-shaped drive piece 32 is formed so as to extend toward the outside, and is similarly formed by a worm wheel 33 or the like that protrudes radially outward and is formed in an arc shape. The annular portion 31 is externally fitted to the cylindrical portion 11 and is slidably supported on the seat surface 13 of the base 10 and rotatably supported by the cylindrical portion 11.
The worm wheel 33 meshes with a worm gear 81 of a step motor 80 described later, and the drive piece 32 engages with an engagement piece 43 of the cam ring 40 to transmit a rotational driving force to the cam ring 40.

  As shown in FIGS. 1 to 4, the cam ring 40 includes an annular portion 41 fitted on the tubular portion 11, three cam surfaces 42 as cam portions formed on the front end surface of the annular portion 41, and the annular portion 41. A substantially fan-shaped engagement piece 43 projecting radially outward from the outer peripheral surface of the lens, a latching piece 44 which also projects radially outward and extends in the optical axis direction L, and also projects radially outward. It is formed by a substantially fan-shaped detected piece 45 or the like. The annular portion 41 is externally fitted to the tubular portion 11 and is rotatably supported by the tubular portion 11 in a state where the annular portion 41 is slidably stacked on the drive ring 30.

  The engagement piece 43 engages with the drive piece 32 when the cam ring 40 rotates clockwise (one direction) with respect to the drive ring 30, and the cam ring 40 counterclockwise (other direction) with respect to the drive ring 30. When rotating, it can be detached from the drive piece 32, and one end of a coil spring 90 is latched to the latching piece 44 to urge the cam ring 40 to rotate clockwise. The three cam surfaces 42 receive the three followers 22 of the lens frame 20 and exert a cam action in the optical axis direction L.

Since the drive ring 30 and the cam ring 40 are disposed adjacent to each other in the optical axis direction L, the rotational driving force of the drive ring 30 is efficiently transmitted from the drive piece 32 to the engagement piece 43 of the cam ring 40.
Further, the drive ring 30 and the cam ring 40 are disposed adjacent to each other in the optical axis direction L, and the drive piece 32 is formed so as to protrude from the outer periphery of the drive ring 30 and extend in the optical axis direction L, and the engagement piece 43. Is formed so as to protrude from the outer periphery of the cam ring 40, and can be engaged and disengaged in the circumferential direction around the optical axis L, so that the structure can be simplified and the apparatus can be thinned in the optical axis direction L. In addition, a mechanism for absorbing or mitigating external impact force or the like can be easily formed.

  As shown in FIGS. 1, 2, and 4 (a), one end of the coil spring 90 is hooked on the hooking piece 44 of the cam ring 40, and the other end is hooked on the hooking pin 14 on the base 10. Thus, the cam ring 40 is urged to rotate clockwise, and the engagement piece 43 is always engaged with the drive piece 32 of the drive ring 30 in a normal state where no impact force is applied from the outside.

  As shown in FIG. 1, FIG. 3, and FIG. 4, the seat ring 50 is a thin plate that is formed in an annular shape and is externally fitted to the tubular portion 11. The rear surface is brought into contact with the follower 22 of the cam ring 40, and the front surface is assembled so as to receive the rear end portion of the compression spring 60.

The compression spring 60 is attached to the outer peripheral surface of the cylindrical portion 11 so as to be positioned on the front side F of the follower 22 with the seating surface ring 50 interposed therebetween, as shown in FIGS. The front end portion is pressed by the presser ring 70 and is held in a compressed state so as to generate a predetermined urging force.
Therefore, the compression spring 60 acts to urge the follower 22 of the lens frame 20 toward the rear side R in the optical axis direction L so as to always contact the cam surface 42 in a normal state.

  As shown in FIGS. 2 to 4, the presser ring 70 is coupled to the front end surface of the cylindrical part 11 in a state where the compression spring 60 fitted in the cylindrical part 11 is pressed from the outside (front side F). And connected to the base 10.

As shown in FIGS. 1, 2, 3, and 4 (b), the step motor 80 has a worm gear 81 fixed to the rotation shaft 80 a and is fixed to the fixing portion 12 of the base 10. The worm gear 81 is engaged with the worm wheel 33 of the drive ring 30.
Here, the step motor 80 is fixed to the base 10 so that the rotation shaft 80a thereof is substantially parallel to the rotation surface of the drive ring 30, that is, substantially parallel to a surface substantially perpendicular to the optical axis direction L. Yes. Therefore, the apparatus can be thinned in the optical axis direction L by causing the longitudinal direction of the step motor 80 to be substantially parallel to the rotation surface of the drive ring 30.

The detection sensor 100 is an optical sensor such as a photo interrupter provided with a light emitting element and a light receiving element, and detects the initial position of the cam ring 40 by detecting the presence or absence of the detected piece 45 of the cam ring 40.
In addition, as the detection sensor 100, you may employ | adopt other sensors other than an optical sensor.

FIG. 5 shows an embodiment in which the lens driving device M is mounted on a mobile phone. That is, as shown in FIG. 5, the mobile phone 200 has various operation buttons 201a arranged therein and various electronic components arranged therein, and is connected to the main body 201 so as to be freely opened and closed. Are formed by a cover body 202 provided with a monitor 202a for displaying the image, a camera unit 203 disposed on the cover body 202, and the like. The lens driving device M of the present invention is applied to the camera unit 203.
As described above, the lens driving device M of the present invention can be easily mounted in the mobile phone 200 that is required to be thin and small.

Next, an operation in a state where this lens driving device is mounted on the mobile phone 200 will be described with reference to FIGS. 2 and 3 and FIGS.
First, in a normal state where no impact force (external force) due to dropping of the mobile phone or the like is received, the engagement piece 43 of the cam ring 40 is driven by the urging force of the coil spring 90 as shown in FIGS. It is in the state engaged with 30 drive pieces 32. In this state, when the step motor 80 rotates in one direction, the drive ring 30 rotates clockwise through the meshing of the worm gear 81 and the worm wheel 33.

  Then, since the engagement piece 43 follows the drive piece 32 by the urging force of the coil spring 90, the cam ring 40 rotates clockwise, and the cam surface 42 exerts a cam action so as to raise the follower 22. Accordingly, the lens frame 20 moves forward (forwards) toward the front F in the optical axis direction L against the urging force of the compression spring 60.

On the other hand, when the step motor 80 rotates in the other direction, the drive ring 30 rotates counterclockwise via the meshing of the worm gear 81 and the worm wheel 33.
Then, the drive piece 32 exerts a rotational torque on the engagement piece 43 against the urging force of the coil spring 90, the cam ring 40 rotates counterclockwise against the urging force of the coil spring 90, and the cam surface 42 The cam action is exerted so as to lower the follower 22. As a result, the lens frame 20 receives the urging force of the compression spring 60 and retracts (retracts) toward the rear R in the optical axis direction L.
Thus, focusing is performed by moving the lens frame 20 in the optical axis direction L.

Here, as shown in FIG. 6, the follower 22 presses the cam surface 42 when receiving the impact force (external force) Fout due to dropping or the like and the lens frame 20 moves (pushes) in the retracting direction. As a result, the cam ring 40 rotates counterclockwise as shown in FIGS. 6 and 7, and the engagement piece 43 is detached from the drive piece 32. Therefore, the drive ring 32 remains stopped without rotating.
Thereby, it is possible to prevent the driving force from being transmitted from the worm wheel 33 to the worm gear 81 in the opposite direction, and it is possible to prevent the worm wheel 33 and the worm gear 81 from being damaged.

Further, as shown in FIG. 8, when the lens frame 20 receives an impact force (external force) Fout ′ that moves (jumps out) in the extending direction, the lens frame 20 has its follower 22 via the seat ring 50. The compression spring 60 is elastically deformed so as to be compressed, and tries to jump out in a direction away from the cam surface 42. Therefore, when the compression spring 60 is elastically deformed, the impact force Fout ′ is relieved and the follower 22 is separated from the cam surface 42, so that the drive ring 30 remains stopped.
As a result, the driving force is not transmitted from the worm wheel 33 to the worm gear 81, and damage to the worm wheel 33 and the worm gear 81 can be prevented as described above.

  According to the above lens driving device, it is possible to prevent damage to the mechanism by ensuring that the impact force (external force) due to dropping or the like can be absorbed or released even when subjected to an impact force (external force) while achieving a reduction in size and thickness. Therefore, the present invention can be easily applied to small portable information terminals such as mobile phones and portable personal computers.

In the above embodiment, the configuration in which one lens frame 20 is moved by the cam ring 40 to perform focusing has been described. However, the present invention is applied to a configuration in which zooming is performed by relatively moving a plurality of lens frames. It may be adopted.
In the above-described embodiment, the configuration in which the annular cam ring 40 is used as the cam member and the annular drive ring 30 is used as the drive member is shown. The invention may be adopted.
In the above-described embodiment, the case where the step motor 80, the worm gear 81, the worm wheel 33, and the like are employed as the drive mechanism has been described. However, the present invention is not limited to this, and the present invention is not limited to this configuration. The invention may be adopted.

  As described above, the lens driving device of the present invention achieves the expected function without causing damage to impact force such as dropping while achieving simplification, miniaturization, thinning, etc. of the structure. Since it can be guaranteed, it is useful not only for small portable information terminals such as cellular phones and portable personal computers, but also for other information terminals equipped with lens optical systems.

It is a disassembled perspective view which shows one Embodiment of the lens drive device which concerns on this invention. It is a front view of the lens drive device shown in FIG. It is a side view of the lens drive device shown in FIG. (A), (b) is a side view of the lens drive device shown in FIG. 1, respectively. It is an external appearance perspective view which shows embodiment which mounted the lens drive device of this invention in the mobile telephone. It is a side view which shows operation | movement of a lens drive device when the external force which retracts a lens frame acts. It is a front view which shows operation | movement of a lens drive device when the external force which retracts a lens frame acts. It is a side view which shows operation | movement of a lens drive device when the external force which extends a lens frame acts.

Explanation of symbols

L Optical axis direction Fout, Fout 'Impact force (external force)
DESCRIPTION OF SYMBOLS 10 Base 11 Cylindrical part 11a Guide hole 12 Fixing part 13 Seat surface 14 Latching pin 20 Lens frame 21 Cylindrical part 22 Follower 23 Opening plate G Lens 30 Drive ring (drive member, drive mechanism)
31 annular part 32 drive piece 33 worm wheel (drive mechanism)
40 Cam ring (cam member, drive mechanism)
41 Annular part 42 Cam surface (cam part)
43 Engagement piece 44 Latching piece 45 Detected piece 50 Seat ring 60 Compression spring 70 Presser ring 80 Step motor (drive motor, drive mechanism)
80a Rotating shaft 81 Worm gear 90 Coil spring 100 Detection sensor

Claims (4)

A lens frame that holds the lens and is supported so as to reciprocate in the optical axis direction; a cam member that exerts a cam action for moving the lens frame in the optical axis direction; and a drive mechanism that drives the cam member. A lens driving device,
The drive mechanism includes a drive member that has a drive piece and is supported in a reciprocating manner, and engages with the drive piece by moving the cam member in one direction and is detached from the drive piece by moving in the other direction. An engagement piece formed on the cam member, and a spring that urges the cam member in one direction to engage the engagement piece with the drive piece,
When an external force is transmitted from the lens frame to the cam member, the engagement piece is formed so as to be detached from the drive piece.
A lens driving device. The lens frame has a follower,
The cam member has a cam portion that engages with the follower and exerts a cam action;
A spring for urging the follower toward the cam portion;
The lens driving device according to claim 1. The drive member is an annular drive ring that is rotatably supported around the optical axis,
The cam member is an annular cam ring that is rotatably supported around the optical axis and has the cam portion on the front end surface in the optical axis direction.
The drive mechanism includes a drive motor and a worm gear directly connected to the drive motor,
The drive ring has a worm wheel that meshes with the worm gear in a part of the outer periphery thereof.
The lens driving device according to claim 2. The drive ring and the cam ring are disposed adjacent to each other in the optical axis direction,
The drive piece protrudes from the outer periphery of the drive ring and is formed to extend in the optical axis direction,
The engagement piece is formed to protrude from the outer periphery of the cam ring.
The lens driving device according to claim 3.

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