JP5020569B2 - Lens drive device - Google Patents

Description

  The present invention relates to a lens driving device that drives a lens in the optical axis direction, and more particularly to a lens driving device that drives a lens frame holding a lens by a screw feed action of a lead screw and a nut.

Conventional lens driving devices include a lens frame that holds a lens, a guide shaft that guides the lens frame in the optical axis direction, a coil spring that biases the lens frame in one direction in the optical axis, and a biasing force of the coil spring. Nuts that abut against the lens frame in a direction against the lens frame, a lead screw screwed into the nut, a stepping motor that rotationally drives the lead screw, a mounting plate that defines the moving end on one side by colliding with the nut, etc. In order to prevent the nut from colliding with the mounting plate and becoming mechanically locked (inoperable), a hemispherical protrusion is provided on the nut to reduce the contact (contact) area with the mounting plate The friction coefficient is made small to make it difficult to be in a mechanical lock state (see, for example, Patent Document 1).
However, in this lens driving device, depending on the contact state between the nut (the hemispherical projection) and the mounting plate, the contact area becomes small, so the contact pressure (surface pressure) increases and the mechanical lock state is established. It may be difficult to release. Moreover, the idea of reducing the contact area is not a fundamental measure for preventing mechanical lock.

In addition, as other lens driving devices, a lens frame, a guide shaft, a coil spring, a nut, a lead screw, a stepping motor, etc. are provided as in the above-described device, and one side of the lens frame (resisting the urging force of the coil spring) It is known that the lead screw has a non-forming portion that does not form a male screw so that the nut does not mesh with the moving end region on the side that moves in the direction to prevent mechanical locking from occurring in this moving end region. (For example, refer to Patent Document 2).
In this apparatus, even if the mechanical lock can be prevented in the moving end region on one side, it is difficult to prevent the mechanical lock in the moving end region on the other side.

Japanese Patent Laid-Open No. 2004-170753 JP 2002-214509 A

  The present invention has been made in view of the above-described problems of the prior art, and its object is to provide a lens frame that holds a lens while simplifying the structure, reducing the number of parts, reducing the size, and the like. An object of the present invention is to provide a lens driving device that can reliably prevent the mechanical locking of a lead screw and a nut when moving to the moving end of the moving range, and reliably guarantee an expected function.

The lens driving device according to the present invention includes a lens frame that holds a lens and is supported so as to be movable in the optical axis direction, a lead screw that extends in the optical axis direction, and is screwed into the lead screw and integrally with the lens frame. And a forcible stop mechanism that forcibly stops the rotation of the lead screw at a predetermined timing immediately before the nut reaches the screw end of the lead screw. A lens driving device for driving a lens frame, wherein the forced stop mechanism includes an engaged portion integrally formed with the lead screw and an engaged portion at a predetermined timing in conjunction with the movement of the lens frame. wherein an engaging member provided on the movable to obtain engaged, a biasing member exerts a biasing force in a direction to disengage the engaging member from the engaged portion, the engaging member to extend in the optical axis direction The swing lever is swingably supported with respect to the swing support shaft. The swing lever includes an engagement piece that can be engaged with the engaged portion and a follower portion that receives a cam action from the lens frame. The lens frame includes a cam portion that exerts a cam action on the follower portion in order to engage the engaging piece with the engaged portion at a predetermined timing .
According to this configuration, when the lead screw rotates, the nut is screwed and the lens frame is driven in the optical axis direction together with the nut. Then, at a predetermined timing when the nut reaches just before the screw end of the lead screw, the forced stop mechanism operates to forcibly stop the rotation of the lead screw. Thereby, the mechanical lock (biting) between the nut and the lead screw is reliably prevented.
In particular, the forcible stop mechanism includes an engaging member and an engaging member that are movably provided to be engaged with the engaged portion at a predetermined timing in conjunction with the engaged portion of the lead screw and the movement of the lens frame. Since it includes an urging member that exerts an urging force in a direction to disengage from the engaged portion, the engaging member operates in conjunction with the movement of the lens frame in the optical axis direction. By engaging, the rotation of the lead screw is forcibly stopped, and the mechanical lock (biting) between the nut and the lead screw is surely prevented.
In this way, by adopting a movable engagement member to interlock with the lens frame, the predetermined timing immediately before the nut bites on the lead screw and causes mechanical lock can be set with high accuracy, and a simple structure Thus, the mechanical lock can be surely prevented.
Further, since the engaging member is a swing lever, the swing lever includes an engagement piece and a follower portion, and the lens frame has a cam portion that exerts a cam action on the follower portion. Therefore, when the lead screw rotates, the nut is screwed. The lens frame is driven in the optical axis direction together with this nut, and the cam part of the lens frame that moves in the optical axis swings at a predetermined timing when the nut reaches just before the screw end of the lead screw. A cam action is exerted on the follower portion of the lever, the swing lever rotates in one direction against the urging force of the urging member, the engagement piece engages with the engaged portion, and the lead screw rotates. Is forcibly stopped, and this prevents the nut and the lead screw from being mechanically locked. In this way, by adopting a swing lever that swings in a plane substantially perpendicular to the optical axis direction in conjunction with the lens frame, the mechanical lock is achieved while achieving thinning and downsizing of the device in the optical axis direction. It can be surely prevented.

In the above configuration, the swing lever adopts a configuration including an engagement piece formed on the free end side away from the swing support shaft and a follower portion formed near the swing support shaft. Can do.
According to this configuration, since the follower portion is disposed on the side closer to the swing support shaft and the engagement piece is disposed on the side far from the swing support shaft, the cam portion is cammed on the follower portion. When a predetermined angle is applied, an amplification effect proportional to the ratio of the separation distance of the follower part to the swing support shaft and the separation distance of the engagement piece is obtained, and the engagement piece is quickly engaged by increasing the stroke. The lead screw can be stopped immediately by engaging with the part.

In the above configuration, a configuration in which the urging member is a torsion spring disposed around the swing support shaft can be adopted.
According to this configuration, since the swing lever and the torsion spring are disposed in substantially the same space boundary, it is possible to reduce the thickness and size of the apparatus by consolidating components.

In the above configuration, it is possible to adopt a configuration including a guide shaft that guides the lens frame in the optical axis direction, and the guide shaft also serves as a swing support shaft of the swing lever.
According to this configuration, since the guide shaft of the lens frame also serves as the swing support shaft of the swing lever, the number of parts can be reduced compared to the case where a dedicated swing support shaft is provided, and the structure is simplified. It is possible to achieve downsizing and the like of the apparatus by integrating the above.

In the above configuration, the lead screw integrally has a support surface that slidably supports the swing lever adjacent to the engaged portion, and the swing lever is in the vicinity of the engagement piece formed. A configuration including a supported portion that is slidably supported by the support surface and a long hole into which the lead screw is inserted while allowing the swinging of the supported portion can be employed.
According to this configuration, the swing lever is controlled by the lead screw through the elongated hole and is regulated within a predetermined swing range, and the supported piece engages with the engaged portion. In the vicinity, it is slidably supported on the support surface of the lead screw.
Therefore, the tilt of the swing lever or deviation from the predetermined swing range can be prevented, and the engaging and disengaging operations can be reliably performed on the swing lever.

In the above configuration, the lead screw has a gear that integrally rotates coaxially so that the rotational driving force is transmitted by meshing, and the engaged portion is formed adjacent to the gear. Can be adopted.
According to this configuration, the stopping force that engages the engaged portion and stops the lead screw is exerted in the vicinity of the gear to which the rotational driving force is applied from the outside, so that the torsional deformation or the like of the lead screw does not occur. The rotation of the lead screw can be reliably stopped at a predetermined timing (a predetermined rotation angle).

In the above configuration, the lead screw has a gear that rotates coaxially and integrally so that a rotational driving force can be transmitted by meshing, and the gear teeth also serve as an engaged portion. be able to.
According to this configuration, by using the gear teeth as the engaged portion, a dedicated part for defining the engaged portion is not required, and the structure is simplified, the apparatus is downsized, the cost is reduced, and the like. Can be achieved.

In the above-described configuration, it is possible to employ a configuration in which the engagement piece and the engaged portion are engaged and released with a stroke within one pitch of the lead screw.
According to this configuration, the swing lever is operated during one rotation of the lead screw to forcibly stop the rotation of the lead screw, so that the predetermined timing for engaging the engaging piece with the engaged portion is set. , It can be set immediately before the pitch end of the lead screw within one pitch. Therefore, the stroke for moving the lens frame in the optical axis direction can be set to an effective length without waste corresponding to the screw region of the lead screw.

  According to the lens driving device of the above configuration, when the lens frame holding the lens moves to the moving end of the moving range while achieving simplification of the structure, reduction of the number of parts, thinning, downsizing, etc. It is possible to obtain a lens driving device that reliably prevents the mechanical locking of the lead screw and the nut, and reliably guarantees the intended function.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.
1 to 9 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 sectional view of the device, and FIG. 3 is a first view included in the device. FIG. 4 is a perspective view showing a part of the first lens group, FIG. 5 is a rear view showing a part of the first lens group, and FIG. 6 is a cross section showing a part of the first lens group. 7 is a perspective view showing a lens frame of the first lens group, FIG. 8 is a perspective view showing a swing lever constituting a part of a forced stop mechanism included in the apparatus, and FIG. 9 is a diagram for explaining the operation of the swing lever. FIG.

  As shown in FIG. 1 and FIG. 2, this apparatus includes a glass filter 11, a base 10 having a substantially rectangular outline to which a CCD 12 as an image sensor is attached, a fixed cylinder 20 fixed to the base 10, and a fixed cylinder. 20 is a cam cylinder 30 that is supported so as to be rotatable and straightly movable inside 20, and a first lens group 40 and a second lens group 50 that are supported so as to be movable in the optical axis direction L inside the cam cylinder 30, and a first lens group. 40 and a guide cylinder 60 that guides in the optical axis direction while restricting rotation of the second lens group 50, a drive mechanism 70 that drives the cam cylinder 30, and the like.

  As shown in FIGS. 1 and 2, the fixed cylinder 20 is formed in a cylindrical shape with a resin material so as to have an axis in the optical axis direction L, and is fixed to the base 10. The fixed cylinder 20 is formed with three cam grooves 21 (partially omitted in the figure) that exert cam action on three follower pins 31 described later on the inner peripheral surface thereof.

As shown in FIGS. 1 and 2, the cam cylinder 30 is formed in a cylindrical shape from a resin material, and is arranged coaxially in a nested manner inside the fixed cylinder 20.
The cam cylinder 30 is formed with three follower pins 31 arranged at equal intervals (approximately every 120 degrees) in the circumferential direction on the outer peripheral surface thereof, an arc-shaped rack portion 32 to which a rotational driving force is transmitted from the outside, and the like. Further, on its inner peripheral surface, three cam grooves 33 that exert a cam action on the first lens group 40 in the optical axis direction L, three cam grooves 34 that exert a cam action on the second lens group 50 in the optical axis direction L, In the front region in the optical axis direction L, an annular groove 35 that receives an engagement piece 63 of a guide cylinder 60 described later is formed.
As shown in FIGS. 1 and 2, the cam groove 33 receives a first follower pin 42 to be described later and exerts a cam action to move the first lens group 40 in the optical axis direction L. The cam groove 34 The second lens group 50 is moved in the optical axis direction L by receiving a second follower pin 52 described later and exerting a cam action.

As shown in FIGS. 1 to 3, the first lens group 40 has a cylindrical member 41 formed of a resin material in a substantially cylindrical shape, projects radially outward on the outer side of the cylindrical member 41, and is equally spaced in the circumferential direction. Three first follower pins 42 that are arranged (at every 120 ° angle) and slidably engage with the cam groove 33, are supported movably in the optical axis direction L on the inner side of the cylindrical member 41, and the lens G1 A lens frame 43 that holds the lens frame, a drive mechanism 140 that drives the lens frame 43 in the optical axis direction L, a forced stop mechanism 240 that forcibly stops a part of the operation of the drive mechanism 140 (rotation of a lead screw 145 described later), and the like. It has.
In the first lens group 40, the cam groove 33 exerts a cam action on the first follower pin 42 by the rotation of the cam cylinder 30, so that the cylinder member 41 moves forward and backward in the optical axis direction L. The lens frame 43 moves forward and backward in the optical axis direction L with respect to the cylindrical member 41.

  Here, as shown in FIGS. 3, 6, and 7, the lens frame 43 passes through a fitting portion 43 a that slidably fits a guide shaft 147 described later and a lead screw 145 described later without contact. In addition, a nut holding portion 43b that holds a nut 146 described later in a non-rotatable manner, a cam portion 43c that engages with a follower portion 241c of a swing lever 241 described later and exerts a cam action are provided.

  As shown in FIGS. 2 to 6, the drive mechanism 140 includes a stepping motor 141 fixed to the cylinder member 41 via a fixing plate 141a, a drive gear 142 directly connected to the rotation shaft of the stepping motor 141, and the cylinder member 41. A gear 143 that is rotatably supported and meshes with the drive gear 142, a gear 144 that meshes with the gear 143 and that is rotatably supported by the cylindrical member 41, and is formed so as to rotate integrally with the gear 144. A lead screw 145 extending to L, a nut 146 fixed to the lens frame 43 and screwed to the lead screw 145, two guide shafts 147 fixed to the cylindrical member 41 and guiding the lens frame 43 in the optical axis direction L, a lens frame Coil springs 148 and the like for urging 43 toward the front in the optical axis direction L are provided.

  In other words, the lens frame 43 is supported by the guide shaft 147 so as to be movable in the optical axis direction L, and when the stepping motor 141 rotates in one direction, the lead screw 145 is moved through the drive gear 142 → the gear 143 → the gear 144. When the stepping motor 141 rotates in the other direction, the nut 146 and the lens frame 43 move to the front F in the optical axis direction L by the screw feed action, and the drive gear 142 → the gear 143 → the gear 144 As a result, the lead screw 145 rotates in the other direction, and the nut 146 and the lens frame 43 move to the rear R in the optical axis direction L by the screw feeding action while resisting the urging force of the coil spring 148. Yes.

  As shown in FIGS. 2 to 8, the forcible stop mechanism 240 rotates integrally with a swing lever 241 and a lead screw 145 as engagement members supported so as to be swingable with respect to one guide shaft 147. A claw plate 242 having a claw 242a as an engaged portion formed as described above, a torsion spring 243 as a biasing member that urges the swing lever 241 in a direction to detach from the claw plate 242, and the like. Yes.

  2, 3, 5, 6, and 8, the swing lever 241 is formed flat in a plane direction perpendicular to the optical axis direction L, and is fixed to the fixed plate 141 a in the optical axis direction L. A circular hole 241a that is slidably disposed between the clawed plates 242 and passes the guide shaft 147 as a oscillating support shaft, and is formed by bending toward the free end away from the oscillating support shaft. An engagement piece 241b that can be engaged with the claw 242a of the plate 242, a follower part 241c that is formed closer to the swing support shaft (circular hole 241a) and that can be engaged with the cam part 43c of the lens frame 43, and an engagement piece 241b A supported portion 241d that is formed in the vicinity and is slidably supported on a support surface 242b of a claw plate 242 described later, and a long hole 241d into which the lead screw 145 is inserted while allowing the swinging of the supported portion 241d. , And a hook portion 241e such that hooking one end of the torsion spring 243.

As shown in FIGS. 4 and 6, the claw plate 242 is integrally fixed to the lead screw 145 so as to be laminated on the upper surface of the gear 144, and the engagement piece 241 b of the swing lever 241 is provided at one place on the outer periphery. A claw 242a as an engaged portion that can be engaged, a support surface 242b that slidably supports a supported portion 241d of the swing lever 241 and the like are provided.
When the lead screw 145 is urged by the torsion spring 243 and the lead screw 145 rotates in one direction, the claw 242a stops immediately when the engagement piece 241b is engaged, and when the lead screw 145 rotates in the other direction, Even if the combined piece 241b is engaged, it is formed in a shape similar to the one-way clutch mechanism so as to allow the lead screw 145 to rotate.
The support surface 242b is configured to slidably support the swing lever 241 in the vicinity of the claw 242a.

As described above, the support surface 242b for swingably supporting the swing lever 241 is provided adjacent to the claw 242a, and the swing lever 241 is slidably supported on the support surface 242b. Therefore, it is possible to prevent the swing lever 241 from engaging and disengaging with certainty.
Further, since the claw plate 242 (the claw 242a) is formed adjacent to the gear 144, the stopping force for stopping the lead screw 145 by engaging with the claw 242a is rotationally driven by the stepping motor 141. Therefore, the rotation of the lead screw 145 can be reliably stopped at a predetermined timing (predetermined rotation angle) without causing torsional deformation of the lead screw 145 and the like.

  As shown in FIGS. 4 and 5, the torsion spring 243 is disposed around a guide shaft 147 as a swinging support shaft, one end of which is hooked on the hooking portion 241e of the swinging lever 241, and the other end of the torsion spring 243. Engaged with the screw 244 implanted in the member 41, the swing lever 241 is biased counterclockwise in FIG. 5, that is, in the direction in which the engagement piece 241b is detached from the claw 242a. .

  Here, the operation of the forced stop mechanism 240 will be described with reference to FIGS. 9A and 9B. First, the lens frame 43 is positioned in a region away from the screw end on the front side F of the screw region of the lead screw 145. 9A, the cam portion 43c of the lens frame 43 is detached from the follower portion 241c, the swinging lever 241 rotates counterclockwise, and the engaging piece 241b becomes a pawl. The attached plate 242 is detached from the claw 242a. At this time, the lead screw 145 is in a freely rotatable state that is not restrained.

  From this state, the stepping motor 141 starts in one direction, the lead screw 145 rotates in one direction, the nut 146 and the lens frame 43 move toward the front F in the optical axis direction L, and the nut 146 At a predetermined timing immediately before reaching the screw end of the lead screw 145, as shown in FIG. 9B, when the cam portion 43c engages the follower portion 241c and exerts a cam action, the lead screw 145 rotates once. (Ie, with a stroke within one pitch of the screw), the swing lever 241 rotates clockwise against the urging force of the torsion spring 243, and the engagement piece 241b is moved to the claw 242a of the claw plate 242. Engage and forcibly stop the rotation of the lead screw 145.

  As described above, the cam portion 43c of the lens frame 43 that moves in the optical axis direction L is cammed on the follower portion 241c of the swing lever 241 at a predetermined timing when the nut 146 reaches just before the screw end portion of the lead screw 145. Since the engaging piece 241b of the swing lever 241 engages with the claw 242a and forcibly stops the rotation of the lead screw 145, the mechanical lock (chamfering) of the nut 146 and the lead screw 145 is reliably prevented. The

  On the other hand, when the stepping motor 141 rotates in the other direction, the lead screw 145 rotates in the other direction, and the nut 146 and the lens frame 43 start to move toward the rear R in the optical axis direction L, the cam portion 43c is moved to the follower. The swing lever 241 is rotated counterclockwise by the urging force of the torsion spring 243 while the lead screw 145 is rotated once by being detached from the portion 241c, and the engagement piece 241b is disengaged from the claw 242a of the claw plate 242. The lead screw 145 can be rotated in a free state.

Here, since the swing lever 241 that swings in a plane substantially perpendicular to the optical axis direction L in conjunction with the lens frame 43 is employed as the engaging member, the apparatus in the optical axis direction L is made thinner and smaller. The mechanical lock can be surely prevented while achieving the above.
The swing lever 241 includes an engagement piece 241b on the free end side away from the swing support shaft (guide shaft 147), and a follower portion 241c closer to the swing support shaft (guide shaft 147). The follower portion 241c is disposed on the side close to the swing support shaft (guide shaft 147) and the engagement piece 241b is disposed on the side far from the swing support shaft (guide shaft 147). Since an amplification effect proportional to the ratio of the separation distance of the follower portion 241c and the separation distance of the engagement piece 241b with respect to the swing support shaft is obtained, the engagement piece 241b is quickly engaged with the claw 242a by increasing the stroke, The lead screw 145 can be stopped immediately.

Further, since the torsion spring 243 disposed around the swing support shaft (guide shaft 147) is employed as the urging member, the swing lever 241 and the torsion spring 243 can be disposed in substantially the same space boundary. This makes it possible to reduce the thickness and size of the apparatus.
In addition, since the guide shaft 147 that guides the lens frame 43 in the optical axis direction L also serves as the swing support shaft of the swing lever 241, the number of parts can be reduced compared to the case where a separate swing support shaft is provided. Further, simplification of the structure, downsizing of the apparatus by consolidating parts, and the like can be achieved.
Further, the engagement piece 241b and the claw 242a are engaged and released by a stroke within one pitch of the screw of the lead screw 145, that is, while the lead screw 145 makes one rotation. The predetermined timing for engaging with 242a can be set immediately before one pitch from the screw end of the lead screw 145. Therefore, the stroke for moving the lens frame 43 in the optical axis direction L can be set to an effective length without waste corresponding to the screw region of the lead screw 145.

As shown in FIGS. 1 and 2, the second lens group 50 is formed in a substantially cylindrical shape by a resin material, and protrudes radially outward from the lens frame 51 that holds the lens G2, the lens frame 51, and the periphery. Three second follower pins 52 that are slidably engaged with the cam grooves 34 and that are slidably engaged with each other are provided at regular intervals (every 120 degrees) in the direction.
The second lens group 50 moves forward and backward in the optical axis direction L when the cam cylinder 30 rotates and the cam groove 34 exerts a cam action on the second follower pin 52.

As shown in FIGS. 1 and 2, the guide cylinder 60 is disposed between the first lens group 40 and the second lens group 50 and the cam cylinder 30, and the first lens group 40 and the second lens group 50 are connected to each other. , While revolving in the optical axis direction L is guided while restricting rotation around the optical axis L.
That is, the guide tube 60 receives the first follower pin 42 of the first lens group 40 and guides it in the optical axis direction L, and receives the second follower pin 52 of the second lens group 50 and receives the first follower pin 52 in the optical axis direction L. Three guide grooves 62 that are guided to the inner periphery of the cam cylinder 30, three engagement pieces 63 that are engaged with an annular groove 35 formed on the inner peripheral surface of the cam cylinder 30, and non-rotatable with respect to the fixed cylinder 20 and in the optical axis direction L A protrusion 64 or the like that is movably engaged is provided.
Here, the guide groove 61 and the guide groove 62 are arranged at equal intervals in the circumferential direction (at an angle of 120 degrees), and are slit-shaped (long holes) that are notched and extend in the optical axis direction L. The groove shape is defined in cooperation with the inner peripheral surface of the cam cylinder 30.

The guide cylinder 60 is fitted to the inner peripheral surface of the cam cylinder 30, and the engagement piece 63 is engaged with the annular groove 35 so that the guide cylinder 60 does not move relatively in the optical axis direction L. The protrusion 64 is hooked on the fixed cylinder 20 so as not to rotate around the optical axis L.
Therefore, when the cam cylinder 30 rotates, the guide groove 61 of the guide cylinder 60 guides the first follower pin 42, which is cammed by the cam groove 33, so as to reciprocate only in the optical axis direction L. The guide groove 62 guides the second follower pin 52, which is cammed by the cam groove 34, so as to reciprocate only in the optical axis direction L.

As shown in FIG. 1, the drive mechanism 70 includes a DC motor 71 fixed to the base 10, a gear train (not shown) that meshes with the rack portion 32 of the cam cylinder 30, and the like. Is transmitted to the cam cylinder 30.
That is, when the DC motor 71 rotates in one direction, the cam cylinder 30 rotates in one direction relative to the fixed cylinder 20 via the gear train, and passes through the wide-angle end position from the retracted position to the first lens group 40. When the second lens group 50 moves forward in the optical axis direction L and moves to the telephoto end position, while the DC motor 71 rotates in the reverse direction, the cam cylinder 30 is moved relative to the fixed cylinder 20 via the gear train. Thus, the first lens group 40 and the second lens group 50 move rearward in the optical axis direction L, pass through the wide-angle end position, and then move to the retracted position.

Next, a general operation when the above lens driving device is mounted on a digital camera will be described. First, at the time of non-shooting, the first lens group 40 and the second lens group 50 are rearward in the optical axis direction L. It is in the retracted position retracted toward.
When the cam cylinder 30 is rotated by the drive mechanism 70 from the retracted position, the follower pin 31 is guided and moved by the cam groove 21, and the cam cylinder 30 is advanced toward the front in the optical axis direction L. Further, the rotation of the cam cylinder 30 causes the first follower pin 42 to be guided by the cam groove 33 while being guided only in the optical axis direction L by the guide groove 61, and the second follower pin 52 is guided by the guide groove 62 in the optical axis direction. The first lens group 40 and the second lens group 50 receive the cam action by the cam groove 34 while being guided only by L, and the front F and rear R in the optical axis direction L are controlled while the rotation relative to the cam cylinder 30 is restricted. To the wide-angle end position and further to the telephoto end position.
On the other hand, when the driving mechanism 70 exerts a driving force in the reverse direction, the first lens group 40 and the second lens group 50 follow the reverse path and return from the telephoto end position to the retracted position.

In the first lens group 40, in addition to the movement of the cam cylinder 30 by the cam groove 33, the lens frame 43 moves relative to the cylinder member 41 in the optical axis direction L by the drive of the drive mechanism 140. Thus, a focusing operation corresponding to zooming is performed.
In this focusing operation, when the lead screw 145 rotates, the nut 146 is screwed and the lens frame 43 is appropriately driven in the optical axis direction L together with the nut 146.

The cam portion 43c of the lens frame 43 that moves in the optical axis direction L is cammed on the follower portion 241c of the swing lever 241 at a predetermined timing when the nut 146 reaches just before the screw end portion on the front side of the lead screw 145. Effect.
As a result, the swing lever 241 rotates in one direction against the urging force of the torsion spring 243, and the engagement piece 241b engages with the claw 242a to forcibly stop the rotation of the lead screw 145. . As a result, mechanical locking (biting) between the nut 146 and the lead screw 145 is reliably prevented.

In the above-described embodiment, the case where the forced stop mechanism 240 is employed to prevent the mechanical lock when the lens frame 43 reaches the screw end portion of the front F in the optical axis direction L is shown, but is not limited thereto. In contrast, the lens frame 43 may be employed to prevent a mechanical lock when the lens frame 43 reaches the screw end of the rear R in the optical axis direction L.
In the above embodiment, the case where the forced stop mechanism 240 is applied to the first lens group 40 in the configuration including the first lens group 40 and the second lens group 50 driven in the optical axis direction L by the cam cylinder 30 is shown. However, the present invention is not limited to this, and in the configuration including the three lens groups of the first lens group to the third lens group, the forced stop mechanism according to the present invention may be adopted for the third lens group. In addition, in a configuration including four or more lens groups, the forced stop mechanism according to the present invention may be employed for at least one of the lens groups.

In the above embodiment, the case where the claw 242a of the claw plate 242 is employed as the engaged portion with which the engagement piece 241b of the swing lever 241 is engaged is shown, but the present invention is not limited to this. When 144 is formed of a hard material, the teeth of the gear 144 that rotates integrally with the lead screw 145 may be used as the engaged portion. In this case, the engagement piece 241b is formed so as to be inclined with respect to the tangent to the pitch circle of the gear 144, so that the configuration is similar to a one-way clutch mechanism that can be engaged with the tooth surface of the gear 144. it can.
According to this, a dedicated part for defining the engaged portion is not required, and the simplification of the structure, the miniaturization of the apparatus, the cost reduction, and the like can be achieved.

  As described above, the lens driving device of the present invention can reliably prevent mechanical locking of the lead screw and nut while achieving simplification of the structure, reduction of the number of parts, thinning, miniaturization, etc. Of course, the present invention can be applied to the lens driving device mounted on the head as long as it employs a driving mechanism including a lead screw and a nut.

It is a disassembled perspective view which shows one Embodiment of the lens drive device which concerns on this invention. It is sectional drawing of the lens drive device shown in FIG. It is a disassembled perspective view which shows the 1st lens group contained in the lens drive device shown in FIG. It is a perspective view which shows the inner side of the 1st lens group contained in the lens drive device shown in FIG. It is a rear view which shows a part inside 1st lens group contained in the lens drive device shown in FIG. It is sectional drawing which shows the inside of the 1st lens group contained in the lens drive device shown in FIG. It is a perspective view which shows the lens frame which makes a part of 1st lens group contained in the lens drive device shown in FIG. It is a perspective view which shows the rocking lever which makes a part of forced stop mechanism contained in the lens drive device shown in FIG. 1A and 1B are diagrams for explaining the operation of a forced stop mechanism included in the lens driving device shown in FIG. 1, in which FIG. 1A is a plan view showing a state where an engaging piece of a swing lever does not restrain a lead screw, and FIG. It is a top view which shows the state which the movement lever stopped rotation of the lead screw.

Explanation of symbols

L Optical axis direction F Optical axis direction forward R Optical axis direction rear G1, G2 Lens 10 Base 11 Glass filter 12 CCD
20 fixed cylinder 21 cam groove 30 cam cylinder 31 follower pin 32 rack part 33, 34 cam groove 35 annular groove 40 first lens group 41 cylindrical member 42 first follower pin 43 lens frame 43a fitting part 43b nut holding part 43c cam part 50 first Two lens group 51 Lens frame 52 Second follower pin 53 Shutter mechanism 60 Guide cylinder 61, 62 Guide groove 63 Engagement piece 64 Projection 70 Drive mechanism 71 DC motor 140 Drive mechanism 141 Stepping motor 142 Drive gears 143, 144 Gear 145 Lead screw 146 Nut 147 Guide shaft (oscillating spindle)
148 Coil spring 240 Forced stop mechanism 241 Swing lever (engaging member)
241a Circular hole 241b Engagement piece 241c Follower part 241d Supported part 241d 'Long hole 241e Hook part 242 Claw plate 242a Claw (engaged part)
242b Support surface 243 Torsion spring (biasing member)
244 screw

Claims (8)

A lens frame that holds the lens and is movably supported in the optical axis direction, a lead screw that extends in the optical axis direction, a nut that is screwed into the lead screw and moves integrally with the lens frame, and A forced stop mechanism for forcibly stopping the rotation of the lead screw at a predetermined timing immediately before the nut reaches the screw end of the lead screw, and the lead screw is rotated so as to be integrated with the nut. A lens driving device for driving a lens frame,
The forced stop mechanism is provided movably to be engaged with the engaged portion integrally formed with the lead screw and to be engaged with the engaged portion at the predetermined timing in conjunction with the movement of the lens frame. an engaging member which is, seen including a biasing member that exerts a biasing force to the engaging member in a direction to disengage from said engaged portion,
The engaging member is a swinging lever that is swingably supported with respect to a swinging support shaft extending in the optical axis direction.
The swing lever includes an engagement piece that can be engaged with the engaged portion, and a follower portion that receives a cam action from the lens frame,
The lens frame has a cam portion that exerts a cam action on the follower portion in order to engage the engagement piece with the engaged portion at the predetermined timing.
A lens driving device. The swing lever includes the engagement piece formed on a free end side away from the swing support shaft, and the follower portion formed near the swing support shaft.
The lens driving device according to claim 1 . The biasing member is a torsion spring disposed around the swing support shaft.
The lens driving device according to claim 1 or 2 , wherein Including a guide shaft for guiding the lens frame in the optical axis direction;
The guide shaft also serves as a swing support shaft of the swing lever;
The lens driving device according to claim 1 , wherein the lens driving device is a lens driving device. The lead screw integrally has a support surface adjacent to the engaged portion to support the swing lever so as to swing freely.
The swing lever includes a supported portion that is slidably supported by the support surface in the vicinity of the engagement piece, and allows the lead screw to be inserted while allowing the swing in the supported portion. Including a long hole,
The lens driving device according to claim 1, wherein The lead screw has a gear that integrally rotates coaxially so that a rotational driving force is transmitted by meshing,
The engaged portion is formed adjacent to the gear.
The lens driving device according to claim 1 , wherein the lens driving device is a lens driving device. The lead screw has a gear that integrally rotates coaxially so that a rotational driving force is transmitted by meshing,
The teeth of the gear also serve as the engaged portion,
The lens driving device according to claim 1 , wherein the lens driving device is a lens driving device. The engagement between the engagement piece and the engaged portion and the release thereof are performed with a stroke within one pitch of the lead screw.
The lens driving device according to claim 1 , wherein the lens driving device is a lens driving device.

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