JP2005024968A - Lens driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens driving device which is strong against impact and prevents the occurrence of an operation failure. <P>SOLUTION: A first rotation stop groove 33 which is engaged with a projecting part 18a and prevents a nut member 18 from being driven to rotate by rotation of a feed screw 17 is integrarlly formed at a lens frame 14. Also, a second rotation stop groove 36 which is engaged with a projecting part 18b and prevents the nut member 18 from being driven to rotate is formed at a holding section which freely rotatably holds the feed screw 17. The rotation stop groove 36 has a clearance slightly larger than the clearance of the first rotation stop groove 33. The first rotation stop groove 33 is shorter than the relative moving range of the nut member 18 and the lens frame 14 and the end of the groove is provided with an inclined part 33a so that the width of the groove is made broader toward the outer side. Further, the lens frame 14 is energized by an energizing spring in such a manner that the nut member 18 and a part 37 are brought into contact with on each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens driving device for an optical apparatus that moves a lens using a feed screw (lead screw).
[0002]
[Prior art]
As the lens driving device, a feed screw arranged in parallel with the optical axis of the lens, a motor for rotationally driving the feed screw, a nut member having a screw hole screwed with a screw portion of the feed screw, a nut member, A lens holding frame that holds the lens and a guide shaft that holds the lens holding frame so as to be movable in the optical axis direction is provided, and the nut member moves in the optical axis direction by rotating the feed screw by a motor. A technique for moving the lens holding frame back and forth in the optical axis direction is known (for example, Patent Document 1).
[0003]
However, in the lens driving device described in Patent Document 1, the nut member and the feed screw are connected, and the nut member and the feed screw do not move relative to each other, and always move together. For this reason, when an impact or the like is applied to the lens holding frame, a load is applied to the thread of the nut member and the thread of the feed screw. was there. In order to solve such a problem, the nut member and the lens holding frame are separated from each other without being connected, and the lens holding frame is biased in the optical axis direction so that the lens holding frame abuts the nut member. A biasing member is provided, and when the feed screw rotates, the nut member moves to move the lens holding frame in the optical axis direction. When an impact or the like is applied to the lens holding frame, the lens holding frame is relative to the nut member. There is known a technique for preventing a load from being applied to the nut member and the thread of the feed screw (for example, Patent Document 2).
[0004]
[Patent Document 1]
JP 2000-275494 A [Patent Document 2]
Japanese Patent Laid-Open No. 2002-296480
[Problems to be solved by the invention]
However, the lens driving device described in Patent Document 2 requires a rotation stopper that prevents the nut member from being driven and rotated by the rotation of the feed screw, and a guide shaft is provided as a rotation stopper. For this reason, when the lens holding frame is moved, the nut member and the guide shaft move relative to each other. Therefore, if the nut member has a burr or the surface of the guide shaft is damaged, a malfunction may occur. there were.
[0006]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a lens driving device that is resistant to impacts and the like and prevents the occurrence of malfunction.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a lens driving device of the present invention includes a lens holding frame that holds a lens and can move forward and backward in the optical axis direction, a feed screw that is arranged in parallel with the optical axis, and is driven to rotate. A screw hole that is screwed into the feed screw is provided, a nut member that moves forward and backward in the optical axis direction by rotation of the feed screw, and a lens holding frame that is engaged with the nut member and is rotated by the feed screw to rotate the nut member. The first rotation stopper that prevents the driven rotation and the holding frame that rotatably holds the feed screw are provided, and the nut member is engaged with the nut member to prevent the nut member from being rotated by the rotation of the feed screw. A second rotation stopper; and a biasing member that biases the lens holding frame so as to abut against the nut member. The lens holding frame is movable relative to the nut member against the biasing of the biasing member. It is characterized by being It is intended.
[0008]
The second rotation stopper has a slightly larger clearance than the first rotation stopper, and the first rotation stopper is formed along the optical axis direction, and is formed between the nut member and the lens holding frame. The groove is shorter than the relative movement range, and an inclined portion is provided at the end of the groove so that the width of the groove becomes wider toward the outside.
[0009]
Further, the first rotation stopper may have a length that allows the entire relative movement range of the nut member and the lens holding frame.
[0010]
In order to solve the above problems, a lens driving device of the present invention includes a lens holding frame that holds a lens and can move forward and backward in the optical axis direction, a feed screw that is arranged in parallel with the optical axis, and is driven to rotate. A screw hole that is screwed into the feed screw is provided, a nut member that moves forward and backward in the optical axis direction by rotation of the feed screw, and a lens holding frame that prevents the nut member from being driven to rotate by rotation of the feed screw. A rotation stopper and a biasing member that biases the lens holding frame so as to contact the nut member are provided, and the lens holding frame is movable relative to the nut member against the biasing of the biasing member. It is characterized by this.
[0011]
The aforementioned rotation stopper preferably has a length that allows the entire relative movement range of the nut member and the lens holding frame.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view of a lens driving device 10 according to the first embodiment of the present invention, and FIG. 2 is an exploded perspective view of the lens driving device 10. The lens driving device 10 includes a base member 12 in which an aperture 11 is formed and fixed to a main body of an optical device such as a camera, a lens frame 14 that holds a lens 13, and a guide shaft that guides the movement of the lens frame 14 in the optical axis direction. 15, 16, a feed screw 17, a nut member 18 screwed to the feed screw 17, a holding portion 19 that is formed integrally with the base member 12 and holds the guide shaft 15 and the feed screw 17, and a guide shaft 15. And an urging spring 20 that urges the lens frame 14 forward in the optical axis direction to abut against the nut member 18.
[0013]
A fitting hole 21 is formed in the base member 12 above the aperture 11, and the guide shaft 16 is fitted and fixed. A fitting hole 22 into which one end of the feed screw 17 is fitted is formed below the aperture 11, and the other end is fitted into a fitting hole 23 provided in the holding portion 19. It is held freely. A nut member 18 is screwed into the feed screw 17. A fitting hole 24 is formed on the right side of the fitting hole 22, the guide shaft 15 is fitted and fixed, and the urging spring 20 is inserted.
[0014]
A motor 25 is provided on the lower left side of the base member 12. The drive of the motor 25 is transmitted to a gear train (not shown) arranged on the back surface of the base member 12, and the feed screw 17 is rotated by the rotation transmission of the gear train. A photo interrupter (PI) 26 is provided on the left side of the aperture 11. The PI 26 is provided to detect the home position (the rearmost position in the optical axis direction) of the lens 13.
[0015]
As shown in FIG. 3, the lens frame 14 holds the lens 13 at the center thereof. Above the lens frame 14, a guide protrusion 31 is integrally formed with a guide groove 30 that engages with the guide shaft 16 formed at the tip. The guide groove 30 and the above-described guide shaft 16 are engaged to guide the movement of the lens frame 14 in the optical axis direction. A guide cylinder 32 through which the guide shaft 15 is inserted is integrally formed below the lens frame 14, and guides the movement of the lens frame 14 in the optical axis direction together with the guide shaft 16 and the holding portion 19. Further, on the left side of the guide tube 32, a first rotation stop groove 33 that engages with the nut member 18 and prevents the nut member 18 from being rotated (corotated) with respect to the rotation of the feed screw 17. Are integrally formed. The first rotation stop groove 33 is shorter than the relative movement range of the nut member 18 and the lens frame 14. The nut member 18 has a substantially cross-shaped front shape, and a protruding portion 18a protruding upward engages with the first rotation stop groove. The front end portion of the first rotation stop groove 33 is provided with inclined portions 33a on the left and right so that the width of the groove is widened on the front side in the optical axis direction.
[0016]
The inclined portion 33a is urged by the urging spring 20 even when the lens frame 14 moves rearward in the optical axis direction due to an impact or the like, and the first rotation stop groove 33 and the projection 18a are once disengaged. As a result, the lens frame 14 is returned to the front in the optical axis direction, guided by the inclined portion 33a, and reliably engaged with the protrusion 18a again. A pressed portion 37 that is in contact with the nut member 18 by the biasing force of the biasing spring 20 is integrally formed below the first rotation stop groove 33.
[0017]
A light shielding lid 34 is integrally formed on the left end portion of the lens frame 14, and a shielding projection 35 is formed on the rear surface of the lens frame 14 so as to protrude toward the rear side of the optical axis. When the lens frame 14 moves to the home position at the rearmost end in the optical axis direction, the shielding projection 35 is inserted between the light projecting portion and the light receiving portion of the PI 26 described above. Accordingly, the PI 26 detects that the lens 13 is at the home position. The shielding lid 34 covers the PI 26 from the front side and shields it when the lens frame 14 moves to the home position, thereby preventing external light from entering the light receiving portion of the PI 26 and generating noise.
[0018]
In addition, the holding portion 19 is engaged with a protruding portion 18 b protruding downward from the nut member 18, and prevents the nut member 18 from rotating (corotating) with the rotation of the feed screw 17. A rotation stop groove 36 is integrally formed. The second rotation stop groove 36 is larger than the shape of the protrusion 18b, and a clearance is secured and the backlash is larger than that of the first rotation stop groove 33 engaged with the protrusion 18a. While this backlash allows slight movement of the nut member 18 in the lateral direction, this clearance is the width at the front end portion of the inclined portion 33a provided at the front end portion of the first rotation stop groove 33 (the widest width). Since the first rotation stop groove 33 and the projection 18a of the nut member 18 are disengaged and then reengaged, the clearance is guided by the inclination 33a. There is an effect that it is easy to match.
[0019]
Next, the operation of the lens driving device 10 having the above configuration will be described with reference to FIG. The lens frame 14 is always urged forward in the optical axis direction by the urging force of the urging spring 20, and is in contact with the nut member 18 at the pressed portion 37. For this reason, when the nut member 18 is at the foremost end in the holding portion 19, the lens frame 14 is at the foremost end position in the optical axis direction (position shown in FIG. 4A). The drive of the motor 25 is transmitted to a gear train provided on the back surface of the base member 12, and the feed screw 17 is rotated by this gear train. At this time, since the rotation of the nut member 18 is prevented by the first rotation stop groove 33 and the second rotation stop groove 36, the nut member 18 moves back and forth in the optical axis direction by the rotation of the feed screw 17. When the nut member 18 moves rearward in the optical axis direction, the nut member 18 presses the pressed portion 37.
[0020]
Since the movement of the lens frame 14 in the optical axis direction is guided by the guide shafts 15 and 16, the lens frame 14 moves rearward in the optical axis direction against the urging of the urging spring 20 by the pressing of the nut member 18, and the nut member When 18 moves to the rearmost position, the lens frame 14 moves to the rearmost position shown in FIG.
[0021]
On the contrary, when the nut member 18 moves forward in the optical axis direction, the lens frame 14 moves along the optical axis direction together with the nut member 18 while the pressed portion 37 contacts the nut member 18 by the biasing force of the biasing spring 20. Move forward. Thus, the lens frame 14 moves forward and backward along the optical axis direction between the foremost end portion shown in FIG. 4A and the rearmost end position shown in FIG.
[0022]
Further, when the lens frame 14 moves rearward in the optical axis direction due to an external impact without moving the nut member 18, the pressed portion 37 is brought into contact with the nut member 18 by the biasing force of the biasing spring 20. Return. When the lens frame 14 is moved to a position (position shown in FIG. 4C) where the engagement between the first rotation stop groove 33 and the projection 18a of the nut member 18 is released due to such an external impact. The lens frame 14 is moved forward in the optical axis direction by the urging of the urging spring 20, and is guided by the inclined portion 33a so that the projection 18a of the nut member 18 and the first rotation stop groove 33 are securely engaged, It returns to the original position (position shown in FIG. 4A). Thus, since the nut member 18 and the lens frame 14 can be moved relative to each other, it is possible to prevent the thread from being damaged by the impact being applied to the thread of the feed screw 17 when receiving an impact. Has been.
[0023]
Further, as the rotation stop of the nut member 18, the first rotation stop groove 33 is provided in the lens frame 14 and the second rotation stop groove 36 is provided in the holding part 19, so that it is not necessary to provide a rotation stop guide shaft. For this reason, malfunction of the nut member 18 is prevented because it does not hinder the movement of the nut member 18 due to burrs of the nut member 18 or scratches on the surface of the guide shaft. Furthermore, the length of the first rotation stop groove 33 is shorter than the relative movement range of the nut member 18 and the first rotation stop groove 33, and the lens driving device 10 can be downsized.
[0024]
Next, the lens driving device 40 according to the second embodiment of the present invention will be described. As shown in FIG. 5, the lens driving device 40 is obtained by lengthening the first rotation stop groove 33 formed in the lens frame 14 of the lens driving device 10. The lens member 41 and the lens frame 14 are provided in the lens frame 41. The first rotation stop groove 42 having a length that allows all the relative movement distances to be integrally formed. In this case, unlike the lens driving device 10 of the first embodiment, the engagement between the nut member 18 and the first rotation stop groove 42 is not released, so that an inclined portion is formed at the front end of the first rotation stop groove 42. Is not provided. Further, the second rotation stop groove 36 may or may not be provided. The same components as those constituting the lens driving device 10 are denoted by the same reference numerals in the drawing, and detailed description thereof is omitted.
[0025]
Next, the operation of the lens driving device 40 according to the second embodiment will be described with reference to FIG. When the nut member 18 is at the foremost end in the holding portion 19, the lens frame 41 is at the foremost end as shown in FIG. From this state, the drive of the motor 25 is transmitted to a gear train provided on the back surface of the base member 12, and the feed screw 17 is rotated by this gear train. At this time, since the rotation of the nut member 18 is prevented by the first rotation stop groove 42, the nut member 18 moves in the optical axis direction by the rotation of the feed screw 17. When the nut member 18 moves to the rear of the optical axis, the nut member 18 presses the pressed portion 43 of the lens frame 14 against the biasing force of the biasing spring 20.
[0026]
Since the movement of the lens frame 14 in the optical axis direction is guided by the guide shafts 15 and 16, the lens frame 14 moves rearward in the optical axis direction by pressing the nut member 18, and the nut member 18 reaches the end position in the holding portion 19. When moved, the lens frame 14 moves to the rearmost position shown in FIG.
[0027]
On the contrary, when the nut member 18 moves forward in the optical axis direction, the lens frame 14 moves along the optical axis direction together with the nut member 18 while the pressed portion 43 contacts the nut member 18 by the biasing force of the biasing spring 20. Move forward. Thus, the lens frame 14 moves forward and backward along the optical axis direction between the foremost end portion shown in FIG. 5A and the rearmost end position shown in FIG.
[0028]
Further, when the lens frame 41 is moved rearward in the optical axis direction due to an external impact without moving the nut member 18, the pressed portion 43 is brought into contact with the nut member 18 by the biasing force of the biasing spring 20. Return. When the lens frame 41 is moved due to such an external impact, the first rotation stop groove 42 is protruded 18a even when it is moved to the position farthest from the nut member 18 (position shown in FIG. 5C). The lens frame 41 can be reliably returned to the original position (the position shown in FIG. 5A) because the engagement is not disengaged. Thus, since the nut member 18 and the lens frame 14 can be moved relative to each other, it is possible to prevent the thread from being damaged by the impact being applied to the thread of the feed screw 17 when receiving an impact. Has been.
[0029]
Further, as in the case of the lens driving device 10 of the first embodiment, as the rotation stop of the nut member 18, the lens frame 14 is provided with a first rotation stop groove, and the holding portion 19 is provided with a second rotation stop groove. Therefore, there is no need to provide a rotation stop guide shaft. For this reason, malfunction of the nut member 18 is prevented because it does not hinder the movement of the nut member 18 due to burrs of the nut member 18 or scratches on the surface of the guide shaft.
[0030]
In the lens driving device 10 according to the first embodiment and the lens driving device 40 according to the second embodiment, the urging spring 20 is arranged behind the lens frames 14 and 41 in the optical axis direction. Instead, for example, the urging spring 20 may be disposed in front of the lens frames 14 and 41 in the optical axis direction, and the lens frames 14 and 41 may be urged rearward in the optical axis direction. In this case, the nut member 18 may be disposed behind the lens frames 14 and 41 in the optical axis direction.
[0031]
【The invention's effect】
As described above, in the lens driving device of the present invention, the nut member and the lens holding frame can be moved relative to each other, and when the lens holding frame is moved due to an external impact or the like, the nut member and the feed screw are threaded. The impact is not applied and the thread is not damaged. Further, since the guide shaft is not used to stop the rotation of the nut member, there is no malfunction caused by the burr of the nut member or the scratch on the surface of the guide shaft. Furthermore, in the lens driving device of the first embodiment, the length of the first rotation stop groove is shorter than the relative movement range of the nut member and the first rotation stop groove, and the lens drive device can be downsized. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a configuration of a lens driving device.
FIG. 2 is an exploded perspective view showing a configuration of a lens driving device.
FIG. 3 is a front view showing a configuration of a lens frame.
FIG. 4 is a cross-sectional view showing the operation of the lens driving device.
FIG. 5 is a cross-sectional view illustrating an operation of a lens driving device according to a modified example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10, 40 Lens drive device 13 Lens 14, 41 Lens frame 15, 16 Guide shaft 17 Feed screw 18 Nut members 18a, 18b Protrusion portion 19 Holding portion 20 Biasing spring 33, 42 First rotation stop groove 33a Inclined portion 36 Second Anti-rotation groove 37, 43 Pressed part

Claims (6)

A lens holding frame that holds the lens and is movable back and forth in the optical axis direction, a feed screw that is arranged in parallel with the optical axis and is driven to rotate, and a screw hole that is screwed into the feed screw are provided. A nut member that moves forward and backward in the optical axis direction by rotation, and a first rotation that is provided on the lens holding frame and engages with the nut member to prevent the nut member from being driven to rotate by rotation of the feed screw. And a second rotation stop provided on a holding frame that rotatably holds the feed screw, and is always engaged with the nut member to prevent the nut member from being driven to rotate by the rotation of the feed screw. A biasing member that biases the lens holding frame so as to contact the nut member, and the lens holding frame is movable relative to the nut member against the biasing of the biasing member. Special that Lens driving device according to. The lens driving device according to claim 1, wherein the second rotation stopper has a slightly larger clearance than the first rotation stopper. The first rotation stopper is a groove that is formed along the optical axis direction and is shorter than the relative movement range of the nut member and the lens holding frame, and the width of the groove toward the outside at the end of the groove. The lens driving device according to claim 1, wherein an inclined portion is provided so as to be wide. 3. The lens driving device according to claim 1, wherein the first rotation stopper has a length that allows the entire relative movement range of the nut member and the lens holding frame. 4. A lens holding frame that holds the lens and is movable back and forth in the optical axis direction, a feed screw that is arranged in parallel with the optical axis and is driven to rotate, and a screw hole that is screwed into the feed screw are provided. A nut member that moves forward and backward in the optical axis direction by rotation, and a rotation stopper that is provided on the lens holding frame and engages with the nut member to prevent the nut member from being driven to rotate by rotation of the feed screw; An urging member that urges the lens holding frame to abut against the nut member, and the lens holding frame is movable relative to the nut member against the urging of the urging member. A lens driving device. The lens driving device according to claim 5, wherein the rotation stopper has a length that allows the entire relative movement range of the nut member and the lens holding frame.

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