JP2011248193A - Lens drive device and lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost lens drive device which prevents damage of its female screw part against shock of a fall, generates no abnormal noises during drive, and has high drive efficiency.SOLUTION: A lens drive device includes lens frames for holding lenses, a lead screw, and a moving member. The moving member has engaging sections to engage with the lens frames. Female screw parts screwed to the lead screw are formed integrally on the two opposed planes of the moving parts so as to be inclined in the reverse direction from each other. The lens drive device moves the moving member and the lens frames in the direction of the optical axis of the lenses by the rotation of the lead screw. The female screw parts has a first female screw part and a second female screw part across the lead screw. The first female screw part has threads formed at both sides of its hole part. Opposite to the hole part, the second female screw part is formed on an elastically deformable arm section. The apex angle θof the second female screw part is smaller than of the apex angle θof a screw part of the lead screw.

Description

  The present invention relates to a lens driving device used in a lens barrel provided in an imaging device such as a camera or a projection device such as a projector.

  Conventionally, a rotating lead screw and a moving member formed with a female screw portion screwed to the lead screw are used, and a lens frame holding a lens group is engaged with the moving member to focus and zoom the lens. There is known a lens driving device that moves the lens.

  Such a lens driving device has a moving member in which a female screw portion that is screwed with a lead screw is formed and an engaging portion that is engaged with a lens frame is formed, and the female screw portion of the moving member is a lead It is known that the two surfaces facing each other with the screw sandwiched are integrally formed with an inclination in opposite directions (see, for example, Patent Document 1).

JP 2009-47798 A

  The lens driving device described in Patent Document 1 has a female screw part having a slope in the opposite direction integrally formed on two surfaces facing each other with a lead screw interposed therebetween, and is low in cost and good in driving efficiency. is there. However, since the female screw part formed facing the hole part has a small number of screw threads and is formed on a plate-like strong wall part, a strong impact in the axial direction of the lead screw due to dropping etc. When the force was applied, the screw thread was rarely damaged, and abnormal noise was sometimes generated during driving.

  In view of the above problems, an object of the present invention is to obtain a low-cost and high-efficiency lens driving device that prevents damage to a female screw portion against a drop impact and does not generate abnormal noise during driving. Is.

  The above object is achieved by the following configuration.

(1) A lens frame that holds the lens group, a lead screw that is rotated by an actuator, and an engagement portion that engages with the lens frame are formed, and a female screw portion that engages with the lead screw is opposed to each other. And a moving member formed integrally with two surfaces having opposite inclinations, and the lead screw rotates to move the moving member and the lens frame in the optical axis direction of the lens group. In the lens driving device, the female screw portion has a first female screw portion and a second female screw portion with the lead screw interposed therebetween, and the first female screw portion is threaded on both sides of the hole portion. The second female screw portion is formed on an elastically deformable arm portion so as to face the hole portion, and the apex angle of the screw portion of the lead screw is θ ₀ , and the second female screw portion When the apex angle of is θ ₂ ,
θ ₀ > θ ₂
A lens driving device characterized by that.

(2) When the width of the vertex of the first female screw portion is L ₁ and the width of the vertex of the second female screw portion is L ₂ ,
L ₁ <L ₂
The lens driving device according to (1), characterized in that:

  (3) The arm portion is elastically deformed in a state where the lead screw is incorporated, and the first female screw portion and the second female screw portion are screwed together while pressing the lead screw. The lens driving device according to (1) or (2).

(4) When the apex angle of the thread portion of the lead screw is θ ₀ and the apex angle of the first female thread portion is θ ₁ ,
θ ₀ > θ ₁
The lens driving device according to any one of (1) to (3), wherein:

  (5) A lens barrel including the lens driving device according to any one of (1) to (4).

  According to the present invention, it is possible to prevent a female screw portion from being damaged even by a drop impact, and to obtain a low-cost and high driving efficiency lens driving device that does not generate abnormal noise during driving.

It is sectional drawing which shows an example of the lens barrel provided with the lens drive device which concerns on this Embodiment. It is the disassembled perspective view which extracted the lens drive device which moves a 2nd lens group lens frame to an optical axis direction. It is a perspective view which shows a moving member. It is a 3rd page figure of a moving member. It is sectional drawing of the state in which the lead screw and the moving member were screwed together. It is an enlarged view of the A section and B section shown in FIG. It is a figure which shows the modification of the shape of a moving member.

  Hereinafter, the present invention will be described with reference to embodiments, but the present invention is not limited thereto.

  FIG. 1 is a cross-sectional view illustrating an example of a lens barrel 100 including a lens driving device according to the present embodiment.

  The lens barrel 100 shown in FIG. 1 has a fixed first lens group 11, a second lens group 12 that is movable in the optical axis direction, a fixed third lens group 13, and a movable lens unit in the optical axis direction. A zoom lens composed of a fourth lens group is included.

  The first lens group 11 is a fixed lens group that includes the first lens 1, the second lens 2, and the third lens 3 and is fixed to the main body 15. The second lens group 12 includes a fourth lens 4, a fifth lens 5, and a sixth lens 6, and is held by a movable second lens group lens frame 22. The third lens group 13 includes a seventh lens 7, an eighth lens 8, and a ninth lens 9, and is held by a third lens group lens frame 23. The third lens group lens frame 23 is a fixed lens group fixed to the main body 15. The fourth lens group 14 is constituted by a single tenth lens 10 in this example, and is held by a movable fourth lens group frame 24.

  The second lens group lens frame 22 and the fourth lens group lens frame 24 are guided by two guide shafts 17 and 18 fixed to the main body 15 and are movable in the optical axis direction. More specifically, two fitting hole portions 22 s formed integrally with the second lens group frame 22 are fitted with the guide shaft 18, and the rotation lock formed integrally with the second lens group frame 22. The portion 22k is engaged with the guide shaft 17. Further, two fitting holes 24 s formed integrally with the fourth lens group frame 24 are fitted with the guide shaft 17, and the rotation locking portions 24 k formed integrally with the fourth lens group frame 24. Is engaged with the guide shaft 18.

  Each of the second lens group lens frame 22 and the fourth lens group lens frame 24 has an optical axis along the guide shafts 17 and 18 together with a stepping motor (not shown) and a moving member moved by a lead screw rotated by the stepping motor. It can be moved in the direction.

  An imaging element holding frame 16 is fixed to the main body 15 behind the fourth lens group 14. Although not shown, an image sensor is fixed to the image sensor holding frame 16 together with an infrared light cut filter and an optical low-pass filter. Reference numeral 31 denotes an iris unit.

  Hereinafter, the lens driving device according to the present embodiment will be described by taking the second lens group frame 22 as an example.

  FIG. 2 is an exploded perspective view of a lens driving device that moves the second lens group barrel 22 in the optical axis direction.

  2, 41 is a stepping motor, 42 is a lead screw, and the lead screw 42 is rotated by the stepping motor 41.

  As shown in the figure, the moving member 51 that is moved by the rotation of the lead screw 42 is in the vicinity of two fitting hole portions 22 s formed integrally with the second lens group lens frame 22 that holds the second lens group 12. Is engaged. More specifically, two cylindrical engaging portions 52 and 53 formed on the moving member 51 are inserted into and engaged with two engaging hole portions 22H formed on the second lens group lens frame 22. . Further, the female screw portion formed on the moving member 51 is screwed with the lead screw 42.

  Accordingly, the moving member 51 is moved by the rotation of the lead screw 42, and the second lens group lens frame 22 engaged with the moving member 51 is guided by the guide shafts 17 and 18 and is moved together with the moving member 51. It has become.

  FIG. 3 is a perspective view showing the moving member 51. 3A and 3B are views of the moving member 51 viewed from different directions.

  FIG. 4 is a three-side view of the moving member 51. 4A is a front view, FIG. 4B is a side view, and FIG. 4C is a rear view.

  As shown in FIGS. 3 and 4, the moving member 51 includes cylindrical engagement portions 52 and 53 that engage with the second lens group lens frame 22, and a U-shaped portion formed in a U-shape. 54 is formed. A first female screw portion 55 and a second female screw portion 56 are formed inside the two opposing surfaces of the U-shaped portion 54, respectively.

  A hole 57 is formed in the center of one of the opposing surfaces of the U-shaped portion 54, and first female screw portions 55 are formed on both sides of the hole 57. Further, a second female screw portion 56 is formed on the opposite surface of the U-shaped portion 54 so as to face the hole portion 57 formed on the one surface. The first and second female screw portions 55 and 56 sandwich the lead screw 42 and are formed corresponding to the lead of the lead screw 42. That is, the inclinations of the first female screw portion 55 and the second female screw portion 56 are formed in opposite directions.

  Further, as shown in the figure, the second female screw portion 56 formed to face the hole portion 57 is separated from the wall portion 58 and is formed in an arm portion 59 that can be elastically deformed.

  FIG. 5 is a cross-sectional view of a state in which the lead screw 42 and the moving member 51 are screwed together.

  As shown in FIG. 5, the first female screw portion 55 and the second female screw portion 56 are formed in a staggered manner with the lead screw 42 interposed therebetween. Furthermore, as shown in the drawing, the second female screw portion 56 is formed with a tooth height smaller than the first female screw portion 55 formed on both sides of the hole portion 57.

  Although not shown, the first female screw portion 55 may be configured to be pressed and biased toward the lead screw 42 by a biasing force of a spring. Thereby, the backlash with respect to rotation of the lead screw 42 can be suppressed.

  FIG. 6 is an enlarged view of a part A and a part B shown in FIG. 6A is an enlarged view of a portion A (second female screw portion), and FIG. 6B is an enlarged view of a portion B (first female screw portion).

As shown in FIG. 6A, the apex angle θ ₂ of the second female thread portion 56 is formed smaller than the apex angle θ ₀ of the thread portion of the lead screw 42. Thereby, the second female screw portion 56 does not contact the apex corner portion of the screw portion of the lead screw 42 having a poor surface condition, and the apex corner portion of the second female screw portion 56 is not in contact with the screw portion of the lead screw 42. It can be in contact with the slope. Thereby, generation | occurrence | production of the noise at the time of a drive can be prevented now.

The width L ₂ of the vertices of the second female screw portion 56 shown in FIG. 6 (a) is larger than the width L ₁ of the vertex of the first female screw portion 55 shown in FIG. 6 (b) .

  Thus, by forming the width of the apex of the second female screw portion 56 large, the impact strength of the thread can be increased. Thereby, it is possible to prevent the thread from being damaged when a strong impact force acts in the axial direction of the lead screw 42. In addition, when an extremely large impact force is applied, the screw thread is low, so that a slight deflection (elastic deformation) of the arm portion 59 causes tooth skipping, which can prevent the screw thread from being damaged, and abnormal noise during driving. Can be prevented, and a decrease in driving efficiency can be prevented.

Similarly, as shown in FIG. 6B, the apex angle θ ₁ of the first female screw portion is formed smaller than the apex angle θ ₀ of the screw portion of the lead screw. As a result, the first female screw portion 55 does not come into contact with the apex angle portion of the screw portion of the lead screw 42 having a poor surface condition, and the apex angle portion of the first female screw portion 55 is changed to the screw portion of the lead screw 42. It can be made to abut against the slope. Thereby, generation | occurrence | production of the noise at the time of a drive can be prevented now.

  FIG. 7 is a diagram illustrating a modification of the shape of the moving member 51. FIG. 7A is a side view showing a single product state of the moving member 51, and FIG. 7B is a view of the moving member 51 when the female screw portion of the moving member 51 and the screw portion of the lead screw 42 are screwed together. It is a side view which shows a state.

  The moving member 51 shown in FIG. 7A has a shape in which the second female screw portion 56 is inclined in the direction of the first female screw portion 55 in a single product state (not screwed with the lead screw 42). It is formed as follows. When the moving member 51 and the lead screw 42 are screwed together, as shown in FIG. 7B, the arm portion 59 is elastically deformed so that the second female screw portion 56 and the first female screw portion 55 face each other. It has become.

  That is, the moving member 51 shown in FIG. 7 is to screw the lead screw 42 while pressing the lead screw 42 by the elastic force of the arm portion 59. As described above, the female screw portion is screwed while pressing the lead screw, whereby rattling between the moving member 51 and the lead screw 42 can be prevented, and in addition to the above effects, backlash can be suppressed. .

  The zoom lens barrel containing four lens groups is taken as an example, and the lens driving device has been explained taking the second lens group barrel of the lens barrel as an example, but the present invention is not limited to this. The present application is applicable regardless of zooming or focusing as long as the moving member is screwed into the lead screw and the moving member and the lens frame are moved along the guide member in the optical axis direction by the rotation of the lead screw. Needless to say.

DESCRIPTION OF SYMBOLS 11 1st lens group 12 2nd lens group 13 3rd lens group 14 4th lens group 15 Main trunk 16 Imaging element holding frame 17, 18 Guide shaft 22 2nd lens group lens frame 23 3rd lens group lens frame 24 4th Lens group frame 41 Stepping motor 42 Lead screw 51 Moving member 52, 53 Engaging portion 54 U-shaped portion 55 First female screw portion 56 Second female screw portion 57 Hole portion 58 Wall portion 59 Arm portion 100 Lens Lens barrel

Claims (5)

A lens frame that holds the lens group;
A lead screw rotated by an actuator;
An engaging part that engages with the lens frame is formed, and a moving member that is integrally formed with an inclined surface in opposite directions on the two opposing faces of the female screw part that engages with the lead screw; Have
In the lens driving device that moves the moving member and the lens frame in the optical axis direction of the lens group by the rotation of the lead screw,
The female screw part has a first female screw part and a second female screw part across the lead screw,
The first female threaded portion is threaded on both sides of the hole,
Opposing to the hole, the second female screw part is formed on an elastically deformable arm part,
When the apex angle of the thread portion of the lead screw is θ ₀ and the apex angle of the second female thread portion is θ ₂ ,
θ ₀ > θ ₂
A lens driving device characterized by that. When the width of the vertex of the first female screw portion is L ₁ and the width of the vertex of the second female screw portion is L ₂ ,
L ₁ <L ₂
The lens driving device according to claim 1, wherein:   The arm portion is elastically deformed in a state where the lead screw is incorporated, and the first female screw portion and the second female screw portion are screwed together while pressing the lead screw. The lens driving device according to 1 or 2. When the apex angle of the thread portion of the lead screw is θ ₀ and the apex angle of the first female thread portion is θ ₁ ,
θ ₀ > θ ₁
The lens driving device according to claim 1, wherein the lens driving device is a lens driving device.   A lens barrel comprising the lens driving device according to claim 1.

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