JP2000098210A - Lens drive device and nut used in the device - Google Patents

Abstract

(57) [Problem] To provide a simple and high-performance lens driving device which does not generate shaft shake of a motor screw or movement play of a lens holding frame, and a nut used in the device. A lens driving device includes: a lens holding frame;
Guide shafts 3 and 4 for guiding the lens holding frame 2 in the thrust direction 9, a motor 5 as a driving source, a lead screw 6 rotated by the motor 5, and a lead screw 6
And the nut 1 for transmitting the movement of the lens holding frame 2 in the optical axis direction 8 by receiving the rotational movement of the nut 1. The nut 1 is fixed to the lens holding frame 2. The nut 1 is provided with a hinge portion 1d. The nut 1 that has received a run-out generated in the radial direction 10 due to the rotational movement of the lead screw 6 makes a flexible movement against the swing generated right and left in the radial direction 9 at the hinge portion 1d. Due to this movement, the nut 1 absorbs the run-out of the lead screw 6 in the radial direction 10, and the play in the thrust direction 9 does not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple and high-performance lens driving device which does not cause shaft shake of a motor screw or play of a lens holding frame, and a nut used in the device.

[0002]

2. Description of the Related Art In an autofocus system used for adjusting the focus of a video camera or the like, the position of a focus lens is controlled. In the control of the lens position, a motor having a lead screw parallel to the optical axis direction is provided near the lens holding frame for holding the lens in order to move the lens over the entire movable range of the lens. A connection component (hereinafter, referred to as a “nut”) is interposed between the lead screw and the lens holding frame. When the motor rotates the lead screw, the nut receives the rotational movement of the lead screw and transmits the movement of the lens holding frame in the optical axis direction.

Conventionally, in order to accurately transmit the power of this motor and to absorb the runout of the lead screw,
A rotation shaft portion is provided between the lens holding frame and the nut. The rotation shaft portion absorbs the blur of the lens holding frame in a direction (radial direction) orthogonal to the optical axis direction. In order to smoothly move each component between the lens holding frame and the nut, the components are fitted in parallel with the optical axis direction (called a thrust direction) by using a reaction force of a spring material. Absorbs backlash.

[0004]

In the above prior art,
This is a structure in which the rotation shaft portion interposed between the lens holding frame and the nut rotates. For this reason, the swinging motion in the rotation direction causes a loss during rotation. In order to reduce this loss, it is necessary to devise the shape of the rotating shaft portion and to adopt (drive) a sufficient precision dimension.

[0005] Further, in the structure in which the respective parts are fitted so that they can be smoothly moved between the lens holding frame and the nut, the smooth movement of the parts is realized in the radial direction, and there is no play in the thrust direction. There is a need to. For this reason, it is necessary to obtain (drive in) the dimensional accuracy of each part, and it is difficult to manage the parts.

[0006] Even when utilizing the reaction force of the spring material,
As in the case described above, it is still necessary to take (drive in) dimensional accuracy, and the number of parts increases.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and has as its object to provide a simple and high-performance lens driving apparatus which does not cause shaft shake of a motor screw or rattling of a lens holding frame, and an apparatus for driving the same. It is to provide a nut used for the device.

[0008]

In order to solve the above problems, a lens driving device according to the present invention includes a lens holding frame for holding a lens, a guide shaft for guiding the lens holding frame in an optical axis direction, and A lens drive comprising: a lead screw that is rotated by a drive source to drive the lens holding frame in the optical axis direction; and a nut that receives the rotational movement of the lead screw and transmits motion of the lens holding frame in the optical axis direction. The device is characterized in that the nut is provided with a hinge portion, and the nut and the lens holding frame are fixed or integrally formed.

Therefore, since the hinge portion is provided on the nut, flexibility can be imparted to the left-right tilt (swing) in the direction (radial direction) orthogonal to the optical axis direction. Therefore, the radial deflection of the lead screw is absorbed. As a result, it is possible to provide a high-precision lens driving device in which the image formed by the lens is prevented from shaking or jumping.

In addition, since the nut and the lens holding frame are fixed or integrally formed, the structure becomes simple, and a play in the moving direction of the lens holding frame and a plane perpendicular to the moving direction occurs. Absent. Therefore, it is possible to reduce the hysteresis when the lens holding frame reversely moves along the optical axis direction.

A nut according to the present invention is a nut for transmitting a movement of a lens holding frame for holding a lens in an optical axis direction by receiving a rotational movement of a lead screw rotated by a driving source. A part is provided.

Since the hinge portion is provided on the nut, flexibility can be given to the left and right inclinations in a direction (radial direction) orthogonal to the optical axis direction.

Preferably, the nut is formed integrally with the nut and the lens holding frame.

Therefore, since the nut and the lens holding frame are integrally formed, the labor and members for fixing the nut and the lens holding frame are not required, and the cost can be reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of a lens driving device according to an embodiment of the present invention, and FIG. 2 is a front view thereof. The lens driving device,
A lens holding frame (moving frame), guide shafts 3 and 4 for guiding the lens holding frame 2 in the optical axis direction (thrust direction) 9, a motor 5 as a driving source, and a lead screw 6 rotated by the motor 5; The nut 1 transmits the rotation of the lead screw 6 to the lens holding frame 2 in the optical axis direction 8.

In the center of the lens holding frame 2, a lens 7 is held. As shown in FIG. 2, a sleeve 8 is provided at the upper right corner on the diagonal centering on the lens 7. The sleeve 8 has a sleeve hole 2g penetrating therethrough. A U-shaped groove 2h, which is a U-shaped groove, is formed at the lower left on the diagonal line of the lens holding frame 2. The main shaft 3 of the guide shafts 3 and 4 is passed through the sleeve hole 2g. On the other hand, the sub shaft 4 of the guide shafts 3 and 4 is inserted and held in the U groove 2h. Thus, the lens holding frame 2 is held movably on the guide shafts 3 and 4 in the optical axis direction (thrust direction) 9.

The nut 1 is positioned and fixed on the upper surface of the sleeve 8 of the lens holding frame 2. As a method of fixing the nut 1 to the lens holding frame 2, for example, a sleeve 8
The base 1e of the nut 1 is heat-welded to the upper surface. Or
Nut 1 on top of sleeve 8 by screwing or hooking
Is caulked and fixed. Alternatively, the nut 1 may be fitted to the lens holding frame 2 using a mold or the like so as not to move.

Here, the nut 1 is a connecting component interposed between the lens holding frame 2 and the lead screw 6, and receives the rotation of the lead screw 6 to move the lens holding frame 2 in the optical axis direction 8. Exercise transmission. Nut 1
Are a rack part 1a, a leaf spring part 1b, and a tooth skip prevention part 1.
c, a hinge portion 1d, and a base portion 1e.
As the material of the nut 1, for example, the whole nut is formed of a synthetic resin. Further, the whole nut or the hinge portion may be formed of metal. FIG. 3 is a plan view of the nut 1 and FIG.
Is a side view of the nut 1. FIG. Note that FIG. 3 shows the nut 1 in a state in which the skipping prevention portion 1c is cut for clarity.

As shown in FIG. 4, the leaf spring portion 1b and the skip prevention portion 1c are formed in a U-shape. The lead screw 6 is inserted between the U-shaped leaf spring portion 1b and the jump prevention portion 1c and the rack portion 1a, and the motor 5 is positioned and fixed in this state (see FIGS. 1 and 2).

A hinge 1d is formed between the rack 1a of the nut 1 and the base 1e. Hinge part 1d
Is formed, for example, by thinning a part of the resin material or metal forming the nut 1. Further, the hinge portion 1d may be formed using a metal leaf spring. In this case, the leaf spring and the nut 1 are fixed to each other by screwing or soldering to form the hinge portion 1d. Further, the leaf spring and the nut 1 may be integrally formed using a mold.

Next, the operation of the lens driving device according to the embodiment of the present invention will be described. When the motor 5 is driven, the lead screw 6 rotates. This rotation is performed by the rack 1a of the nut 1 and the leaf spring 1b.
And received at. At this time, a direction (radial direction) orthogonal to the optical axis direction 9 due to the rotational movement of the lead screw 6
The run-out occurs in 10. However, the nut 1 that has received the deflection makes a flexible movement against the falling (swinging) that occurs on the right and left sides in the radial direction 10 at the hinge portion 1d. Due to the movement of the hinge portion 1d, the nut 1 absorbs the run-out generated in the radial direction 10 of the lead screw 6. The rotational movement of the lead screw 6 received by the nut 1 is transmitted to the front-rear movement along the optical axis direction (thrust direction) 9 of the lens holding frame 2. Then, the lens holding frame 2 fixed to the nut 1
Moves back and forth along the thrust direction 9.

According to the above-described embodiment, since the nut 1 is provided with the hinge portion 1d, the nut 1 is provided with flexibility in the right-and-left tilt (swing) in the direction (radial direction) 10 orthogonal to the optical axis direction 9. Can be. Therefore, the vibration which occurs in the radial direction 10 right and left of the lead screw 6 is absorbed, and the shaft deviation of the motor screw 6 is prevented. As a result, the lens 7
Thus, it is possible to provide a high-precision image by suppressing the shaking and flying of the image formed by the method.

Further, since the nut 1 and the lens holding frame 2 are fixed, the structure becomes simple, and there is a play in the moving direction (thrust direction 9) of the lens holding frame 2 and in a plane perpendicular to the thrust direction 9. Absent. Therefore, it is possible to reduce the hysteresis when the lens holding frame 2 reversely moves along the optical axis direction.

Further, since the rotating shaft is not interposed between the nut and the lens holding frame as in the prior art, a fitting portion (for fitting the rotating shaft between the nut and the lens holding frame) is required. (A rotatable fitting portion) can be eliminated. Therefore, it is possible to reduce important management dimensions and reduce costs. That is, since the rotating shaft is not provided, a clearance (clearance) for the rotating shaft and its bearing can be eliminated. As a result, compared to the prior art, which requires a sufficient dimensional accuracy for the fitting portion of the rotating shaft portion in order to prevent occurrence of backlash.
Important management dimensions can be reduced. As a result, simplification can be achieved by eliminating the need for metal mold preparation and component management, etc., which were conventionally required to obtain sufficient dimensional accuracy, and cost can be reduced.

Further, since the rotary shaft is not provided, a conventional lens driving device having a rotary shaft (for example, a structure in which a rotary shaft is provided between a lens holding frame and a nut, a rotary shaft and a guide). As compared with a structure in which the shaft is shared, there is no rotation loss due to the rotation of the rotating shaft and the swinging motion. As a result, the performance of the lens driving device is improved.

Further, there is no need for a spring for absorbing the backlash in the thrust direction 9 as in the prior art.
Therefore, the number of parts can be reduced, and
The number of assembling steps for assembling the spring can be reduced. As a result, cost can be reduced.

In the above embodiment, the nut 1 itself is formed separately from the lens holding frame 2, and the nut 1 and the lens holding frame 2 are fixed when assembling the lens driving device. 1 and the lens holding frame 2 may be integrally formed in advance. In this case, labor and members for fixing the nut 1 and the lens holding frame 2 become unnecessary,
Cost can be reduced.

[0028]

As described above, according to the present invention, there is provided a simple and high-performance lens driving device which does not cause the shaft deviation of the motor screw or the play of the movement of the lens holding frame, and a nut used in the device. be able to.

[Brief description of the drawings]

FIG. 1 is a side plan view of a lens driving device according to an embodiment of the present invention.

FIG. 2 is a front view of the lens driving device according to the embodiment of the present invention.

FIG. 3 is a plan view of the nut 1 according to one embodiment of the present invention.

FIG. 4 is a side view of the nut 1 according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Nut, 1a ... Rack part, 1b ... Leaf spring part, 1c ...
Tooth skip prevention portion, 1d: hinge portion, 1e: base portion, 2 ...
Lens holding frame (moving frame), 2g ... Sleeve hole, 2h ... U
Groove, 3 main shaft, 4 sub shaft, 5 motor, 6 lead screw, 7 lens, 8 sleeve, 9 optical axis direction (thrust direction), 10 direction orthogonal to optical axis (radial direction) ).

Claims (3)

[Claims] 1. A lens holding frame for holding a lens, a guide shaft for guiding the lens holding frame in the optical axis direction, and a lead screw rotated by a driving source to drive the lens holding frame in the optical axis direction. A nut for transmitting the movement of the lens holding frame in the optical axis direction by receiving the rotational movement of the lead screw, wherein the nut is provided with a hinge portion, and the nut and the lens holding frame are provided. And a lens drive device characterized by being fixed or integrally formed. 2. A nut for transmitting a movement of a lens holding frame for holding a lens in an optical axis direction in response to a rotational movement of a lead screw rotated by a drive source, wherein the nut is provided with a hinge portion. And nuts. 3. The nut according to claim 2, wherein the nut and the lens holding frame are integrally formed.