JP2003090950A - Lens driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a lens driving device thin along its optical axis and small- sized, and so on. SOLUTION: The lens driving device is equipped with a lens holding member 30 which holds a lens, a guide shaft 40 which guides the lens holding member 30 freely movably in the direction L of the optical axis, a base 10 where the guide shaft 40 is fixed, a lead screw 54 which threadably engages a female screw part 35a of the lens holding member 30 to move it along the direction L of the optical axis, and a stepping motor 51 which applies a driving force to the lead screw 54; and the output shaft 51a of the stepping motor 51 and the lead screw 54 are arranged, side by side, almost in parallel to the optical- axis direction L. Consequently, the size in the optical axis direction can be made small and the device can be made small-sized and, specially, thin along the optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving device which is mounted on, for example, a digital camera or the like, and which performs a zooming operation by moving a lens in the optical axis direction, and more particularly,
The present invention relates to a lens driving device including a lead screw and a drive motor that applies a driving force to the lead screw.

[0002]

2. Description of the Related Art As a conventional lens driving device, a base, a guide shaft fixed to the base, a lens holding member which holds a lens and is guided by the guide shaft so as to be movable in the optical axis direction, and a lens holding member. It is known that a female screw portion integrally formed with a lead screw, a lead screw screwed into the female screw portion, a drive motor that applies a driving force to the lead screw, and the like are provided.

As shown in FIG. 7, one end of the lead screw 1 is directly connected to the output shaft 2a of the drive motor 2 by press fitting, and when the drive motor 2 rotates, the lead screw 1 directly leads at the rotational speed. The screw 1 is rotated, and the lens holding member 3 is moved in the optical axis direction L via the female screw portion 3a screwed to the male screw portion 1a.

[0004]

However, as described above, the lead screw 1 and the output shaft 2 of the drive motor 2 are used.
In the configuration in which a and are directly connected and aligned in a straight line, a storage space corresponding to the total length of the lead screw 1 and the total length of the drive motor 2 is required, and the total length of the device in the optical axis direction L becomes long. There was a problem of increasing the size.

Further, since the rotation speed of the drive motor 2 is transmitted to the lead screw 1 as it is, the movement pitch when moving the lens holding member 3, that is, the resolution at the time of driving is reduced to enable fine adjustment. In order to achieve this, it is necessary to reduce the screw pitch of the lead screw 1, which leads to an increase in manufacturing cost.

The present invention has been made in view of the above points, and it is an object of the present invention to reduce the thickness particularly in the optical axis direction, and further to reduce the size of the entire apparatus by integrating the parts. Another object of the present invention is to provide a lens drive device that can set an arbitrary reduction ratio between the drive motor and the lead screw without reducing the screw pitch.

[0007]

A lens driving device of the present invention comprises a lens holding member for holding a lens, a guide member for movably guiding the lens holding member in the optical axis direction, and a base for fixing the guide member. A lens driving device comprising: a lead screw that is screwed to a part of the lens holding member to move the lens holding member in the optical axis direction; and a drive motor that exerts a driving force on the lead screw. The output shaft and the lead screw are arranged substantially parallel to and parallel to the optical axis direction. According to this configuration, since the lead screw and the drive motor are arranged side by side in parallel with the optical axis direction, the dimension in the optical axis direction can be shortened, and the device can be downsized.
In particular, it can be thinned in the optical axis direction.

In the above structure, the drive motor and the lead screw may be connected by a gear train to transmit the driving force. According to this configuration, the reduction ratio from the drive motor to the lead screw can be arbitrarily set by appropriately selecting the gear train. This makes it possible to reduce the resolution during driving and enable fine adjustment without reducing the screw pitch of the lead screw.

In the above structure, the drive motor and the lead screw can both be positioned with respect to the base. According to this configuration, since the drive motor and the lead screw are positioned with respect to the common base, it is possible to manage the mutual axial intervals with high accuracy, and particularly when connecting the two by a gear train. Backlash etc. can be removed efficiently.

In the above structure, the base is formed with a first base portion and a second base portion having a two-stage structure, and the gear train is arranged in a space between the first base portion and the second base portion. A configuration can be adopted in which a lead screw is rotatably supported on one base portion and a drive motor is fixed on the second base portion. With this configuration, the lead screw and the drive motor can be arranged as close to each other as possible, and the size of the device can be reduced by integrating the parts. If the lead screw and the drive motor are arranged on a common base on the same plane, the drive motor is placed on one side of the base and the lead screw is placed on the base because of the interposition of the gear train. It is necessary to place the drive motor on the other surface or to fix the drive motor to the side wall of the device away from the lead screw, but by making the base into a two-stage structure, both sides are close to each other in parallel on the same side of the base. Can be arranged. This allows
In addition to thinning the device in the optical axis direction, it is possible to reduce the size in the direction perpendicular to the optical axis direction by the integration.

In the above structure, the second base portion has a fitting hole into which a part of the main body of the drive motor is fitted, and a cutout portion in which a part of the fitting hole is cut out so as to pass the output shaft of the drive motor. It is possible to adopt a configuration having ,. According to this configuration, the drive motor can be easily positioned and fixed to the second base by mounting it in the fitting hole, so that the axial distance to the lead screw can be controlled with high accuracy by a simple mounting operation. Further, even when a gear having a diameter larger than the fitting hole is fixed to the output shaft, it can be easily fixed by passing the output shaft through the notch.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 6
1 shows an embodiment of a lens driving device according to the present invention. FIG. 1 is a front view showing an internal structure as seen from the optical axis direction, FIGS. 2 and 3 are side sectional views, and FIGS. Is a bottom sectional view, and FIG. 6 is a front view showing a part of the internal structure.

This lens driving device, as shown in FIGS. 1 to 3, has a substantially rectangular base 10 and a base 10.
A cover 20 and a lens holding member 3 which are joined to
0, a guide shaft 40 as a guide member that guides the lens holding member 30 in the optical axis direction, a drive mechanism 50 that drives the lens holding member 30 in the optical axis direction, and a transmission that detects the position of the lens holding member 30 in the optical axis direction. A photo interrupter 60 of a mold is provided.

The base 10 serves as a reference for mounting various parts, and as shown in FIGS. 1 and 2,
A frame portion 11 is formed in a rectangular shape in the substantially central portion thereof, and a face plate 12 and a CCD 13 as an image pickup element are attached to the back surface side thereof. Also, the base 10
As shown in FIGS. 2, 4, and 5, on the front surface (inside) of the first base portion 1 located at the rearmost side in the optical axis direction L.
4, the second base portion 1 protruding from the side surface of the frame portion 11 and arranged in parallel to the front side of the first base portion 14 in the optical axis direction L.
5, the protruding base 16 for attaching the photo interrupter 60, the fixing portion 17 for fitting and fixing the guide shaft 40, etc. are integrally molded. Where the first
The base portion 14 and the second base portion 15 form a two-stage structure that defines a space R at a predetermined interval in the optical axis direction L, and in the space R, a gear train G and the like described later are arranged. .

The cover 20 is joined to the base 10 and covers the whole, and an opening 21 is formed in the front in the optical axis direction L, and a cover for protecting the lens from the front of the opening 21. A cap 22 is attached.

As shown in FIGS. 1 to 3, the lens holding member 30 is a cylindrical portion 3 for holding the lenses G1, G2, G3, G4, G5 which are sequentially arranged in the optical axis direction L.
1. A plate-shaped portion 32 that holds a shutter mechanism S that opens and closes an opening for exposure between the lens G2 and the lens G3,
Drive having a guide connecting portion 33 having a connecting hole 33a into which the guide shaft 40 is inserted, a U-shaped groove portion 34 engaged so as to sandwich the guide shaft 40, and a female screw portion 35a into which a lead screw 54 described later is screwed. It is formed by a detected plate 36 and the like formed so as to project from the connecting portion 35 and the guide connecting portion 33.

Guide shaft 40 as a guide member
As shown in FIG. 4, one end thereof is fitted into a fitting hole 17a of a fixing portion 17 integrally formed with the base 10,
Further, the other end is fitted into a fitting hole 23 formed in the cover 20 and firmly joined to the base 10 so as to guide the lens holding member 30 in the optical axis direction L with high accuracy. There is. That is, one guide shaft 40 inserted into the guide connecting portion 33 (connecting hole 33a) prevents the lens holding member 30 from tilting, and the other guide shaft 40 engaged with the U-shaped groove portion 34 corresponds to the lens. The rotation of the holding member 30 is prevented, and the lens holding member 30 is guided while being positioned in the optical axis direction L with high accuracy.

The drive mechanism 50, as shown in FIGS. 1, 2, 4 and 5, is a step motor 5 as a drive motor.
1, a first gear 52 coupled to the output shaft 51a of the step motor 51, a second gear 53 meshing with the first gear 52, a lead screw 54 coupled so as to rotate integrally with the second gear 53, etc. Has been formed. Here, the step motor 5 is configured by the first gear 52 and the second gear 53.
Gear train G for transmitting the driving force of No. 1 to the lead screw 54
Are formed.

As shown in FIGS. 2, 4, 5, and 6,
The step motor 51 is placed on the second base portion 15 formed integrally with the base 10, and the fitting portion 51b (a part of the main body) is fitted and positioned in the fitting hole 15a,
A screw 15d is fastened and fixed to the screw hole 15c through the flange portion 51c. In this state, step motor 5
The first output shaft 51a is substantially parallel to the optical axis direction L. The first gear 52 is fixed to the output shaft 51a.

Here, in the second base portion 15, as shown in FIG. 6, in addition to the fitting hole 15a and the screw hole 15c, a cutout portion 15b for cutting a part of the fitting hole 15a is formed. ing. Therefore, when the step motor 51 to which the first gear 52 is already fixed is attached to the second base portion 15, first, the output shaft 51a having a small diameter is cut into the cutout portion 15b.
Positioning and mounting can be easily performed by positioning the fitting portion 51b in the fitting hole 15a by fixing the fitting portion 51b by fitting the fitting portion 51b into the fitting hole 15a.
In particular, even when the outer diameter of the first gear 52 is larger than the diameter of the fitting hole 15a, the first gear 52 can be easily attached to the output shaft 51a in a fixed state.

As shown in FIG. 4, the lead screw 54 has a drive connecting portion 3 of the lens holding member 30 on a part of the outer peripheral surface thereof.
5 (female screw portion 35a) has a male screw portion 54a to be screwed, and one end portion of the bearing of the base 10 is substantially parallel to the optical axis direction L when the second gear 53 is fixed. Hole 1
8 and the other end is inserted into the bearing hole 24 of the cover 20 and is rotatably supported with respect to the first base portion 14. Therefore, when the step motor 51 rotates, the lead screw 54 rotates via the output shaft 51a, the first gear 52, and the second gear 53, and the lens holding member 30 is moved in the optical axis direction L to capture an image of the CCD 12. The zooming operation is performed on the surface.

Here, the output shaft 5 of the step motor 51 is
1a and the lead screw 54 are respectively in the optical axis direction L
Since they are arranged substantially parallel to each other and in parallel with each other in close proximity to each other, the dimension in the optical axis direction L is shorter than that of the structure in which both are aligned, and the device can be thinned. .

Further, since the lead screw 54 and the step motor 51 are respectively arranged on the first base portion 14 and the second base portion 15 having the two-stage structure, the first gear 52 and the second gear forming the gear train G are formed. 53 and the first base portion 1
4 and the second base portion 15 can be arranged in the space R, whereby the lead screw 54 and the step motor 51 can be arranged close to each other.

If it is attempted to arrange the lead screw 54 and the step motor 51 on the common base 10 on the same surface without forming the two-step structure, the step motor 51 is moved because the gear train G is interposed. On one surface (for example, outer surface) of the base 10 and the lead screw 5
4 is arranged on the other side surface (for example, the inner side surface) of the base 10, or when arranged on the same side, the step is performed on the side wall of the device away from the lead screw 54 or via a separate bracket or the like. It is necessary to fix the motor 51.

On the other hand, by forming the base 10 in a two-step structure (the first base portion 14 and the second base portion 15), the base 10 and the base 10 are arranged in parallel and close to each other on the same side (inside). be able to. As a result, in addition to thinning the device in the optical axis direction L, it is possible to reduce the width and size in the direction perpendicular to the optical axis direction L due to the integration.

Since the step motor 51 and the lead screw 54 are fixed or supported by the common base 10 which integrally forms the second base portion 15 and the first base portion 14, both of them are provided. It is possible to accurately position and manage the inter-axis distance between the first gear 52 and the second gear 52.
The gear 53 and the gear 53 can be positioned at a predetermined position. As a result, backlash between the two can be efficiently removed.

Further, by interposing the first gear 52 and the second gear 53, the reduction ratio from the output shaft 51a to the lead screw 54 can be appropriately selected to any value. Therefore, even if the screw pitch of the lead screw 54 is not reduced, the movement pitch of the lens holding member 30, that is, the resolution when driving the lens holding member 30, can be reduced, and fine adjustment can be performed.

The transmissive photo interrupter 60 is shown in FIG.
As shown in FIG. 5, a main body 61 having a light emitting portion 61a and a light receiving portion 61b built therein and having a substantially cubic outline, a terminal 62 protruding from the rear of the main body 61, a light emitting portion 61a and a light receiving portion 61.
It is formed by a gap portion (slit) 63 and the like formed with a predetermined width with respect to b. And the gap 63
The plate 36 to be detected enters the light receiving portion 6 from the light emitting portion 61a.
When the light beam going to 1b is blocked, the position (for example, the home position) of the plate 36 to be detected, that is, the lens holding member 30 in the optical axis direction L is detected at this point.

On the other hand, as shown in FIGS. 1, 3 and 4, the protruding base 16 to which the photo interrupter 60 is attached is perpendicular to the width direction of the flat portion 16a on which the lower surface 61c of the main body 61 is placed and the gap portion 63. The contact portion 16b that abuts the end surface 61d of the body 61 in different directions, the fitting portion 16c that is formed continuously with the contact portion 16b and is fitted into the gap 63, and the end portion of the contact portion 16b. The guide portion 16d and the like formed by the above are integrally formed.

The fitting portion 16c is formed in a substantially rectangular parallelepiped shape, and fits into the gap portion 63 without any gap to position the gap portion 63. Here, the fitting portion 16c
Is set to be the same as the predetermined width of the gap portion 63 or set to be slightly smaller so that a loose fit can be performed. The distance between the fitting portion 16c and the guide portion 16d is
The width of the light emitting portion 61a is set to be larger than the width on the built-in side. Further, the width of the fitting portion 16c is set larger than the width of the detected plate 36.

That is, the predetermined width of the gap 63 ≧ the fitting portion 1
6c> width of the plate 36 to be detected. As specific dimensions, for example, the gap 63 has a predetermined width of about 1.0 mm, the detection plate 36 has a width of about 0.5 mm, and the fitting portion 16c has a width of 1.0 mm or less and a width of 0. 5
It is set larger than mm.

Therefore, by adopting a simple structure of the fitting portion 16c, the base 10 (protruding base 1
The gap portion 63 can be positioned with respect to 6). In particular, since the gap portion 63 of the photo interrupter 60 is directly positioned by the fitting portion 16c, there is no error stacking, and the gap portion 63 is positioned with respect to the detection target plate 36 with high accuracy.

Next, the operation of the lens driving device will be described. First, when the step motor 51 rotates, the lead screw 54 is rotated via the output shaft 51a, the first gear 52, and the second gear 53. Then, the male screw part 5
The lens holding member 30 is moved in the optical axis direction L by screwing the 4a and the female screw portion 35a.

Then, the lens holding member 30 moves in the optical axis direction L.
When the plate 36 moves toward the rear of the
And blocks the light from the light emitting portion 61a toward the light receiving portion 61b. The home position of the lens holding member 30 is detected at the time of this interruption (light blocking).

On the other hand, when the step motor 51 rotates in the reverse direction, the lead screw 54 rotates in the reverse direction, the lens holding member 30 is moved forward in the optical axis direction L, and the plate 36 to be detected is also separated. The part 63 is moved in a direction away from the light blocking position to release the light blocking state. By moving the lens holding member 30 in the optical axis direction L, the CCD 1
A zooming operation, a zooming operation, and a zooming operation are performed on the image pickup surface of No. 3.

In this series of operations, the step motor 51 and the lead screw 54 have the same base 10 with different surface positions (the first base portion 14 and the second base portion 15 integrally formed). Since it is fixed to or supported by, the backlash and the like can be efficiently removed, and the driving force can be transmitted smoothly. Further, since the driving force is transmitted through the gear train G, a desired reduction ratio can be set, and when the lens holding member 30 is moved in the optical axis direction L, fine adjustment thereof can be performed. it can.

Further, the gap portion 63 of the photo interrupter 60 is formed in the fitting portion 16c of the base 10 (protruding base 16).
Thus, since the plate to be detected is directly positioned with respect to the plate to be detected 36, the plate to be detected 36 can be smoothly moved without coming into contact with the side surface of the gap portion 63 or the like, whereby a highly accurate detection operation is performed.

In the above embodiment, two gears (first gear 52 and second gear 53) are adopted as the gear train G, but the gear train is not limited to this, and a gear train composed of a plurality of gears is used. May be In the above embodiment, the step motor 51 and the lead screw 54
Although one lens holding member 30 driven by the above is shown, the present invention is not limited to this, and a device having two, three, or more lens holding members can also be used.
The present invention can be applied.

[0039]

As described above, according to the lens driving device of the present invention, when the lead screw for moving the lens holding member in the optical axis direction and the driving motor for exerting a driving force on the lead screw are arranged. By arranging the output shaft of the drive motor and the lead screw so as to be substantially parallel to and parallel to the optical axis direction, the dimension in the optical axis direction can be shortened, and the device can be downsized, especially thin. be able to. In addition, by connecting the drive motor and the lead screw with a gear train, the reduction ratio from the drive motor to the lead screw can be set arbitrarily, which allows resolution during driving without reducing the screw pitch of the lead screw. Can be reduced to allow fine adjustment.

Further, by positioning the drive motor and the lead screw with respect to a common base integrally formed, the mutual axial distance can be controlled with high precision, and especially, both of them are connected by a gear train. Backlash etc. can be removed efficiently. In addition, the base has a two-stage structure of a first base portion and a second base portion, a lead screw is supported by the first base portion, a drive motor is fixed to the second base portion, and a space is provided between the two base portions. By arranging the gear train, the lead screw and the drive motor can be arranged as close to each other as possible, and the size of the device can be reduced by integrating the parts. Further, the drive motor can be easily positioned and attached by providing the second base portion with the fitting hole and the cutout portion.

[Brief description of drawings]

FIG. 1 is a front view showing an internal structure of an embodiment of a lens driving device according to the present invention.

FIG. 2 is a side sectional view of the lens driving device shown in FIG.

FIG. 3 is a side sectional view of the lens driving device shown in FIG.

FIG. 4 is a cross-sectional view of the lens driving device shown in FIG. 1 seen from below.

5 is a partial cross-sectional view of the lens driving device shown in FIG. 1 as viewed from below.

6 is a front view showing the internal structure of the lens driving device shown in FIG. 1. FIG.

FIG. 7 is a perspective view showing a relationship between a drive motor and a lead screw in a conventional lens driving device.

[Explanation of symbols] 10 base 11 frame 14 First base part 15 Second base part 15a fitting hole 15b Notch 15c screw hole 15d screw 18 Bearing hole 20 cover 30 lens holding member 35 Drive Connection 35a Female screw part (a part of lens holding member) 36 Detected plate 40 Guide shaft (guide member) 50 drive mechanism 51 Step Motor (Drive Motor) 51a Output shaft 51b Fitting part (part of main body) 51c Flange part 52 1st gear 53 Second gear 54 lead screw 54a Male screw part 60 photo interrupters L optical axis direction R space G gear train

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02B 7/04 EF term (reference) 2H044 BD01 BD11 BD12 BE03 BE06 BE08 BE16 BE20 DA02 DB03 DD01 DD08 5C022 AB21 AB44 AB66 AC42 AC54 AC74 AC78 5C024 CY00 EX22 EX42 GY01

Claims (5)

[Claims] 1. A lens holding member for holding a lens, a guide member for movably guiding the lens holding member in an optical axis direction, a base for fixing the guide member, and a screw for a part of the lens holding member. A lens driving device comprising: a lead screw that moves the lens holding member in the optical axis direction in combination; and a drive motor that applies a driving force to the lead screw, wherein an output shaft of the drive motor and the lead screw. Is
They are arranged substantially parallel to and parallel to the optical axis direction,
A lens driving device characterized by the above. 2. The lens driving device according to claim 1, wherein the drive motor and the lead screw are connected by a gear train to transmit a driving force. 3. The lens driving device according to claim 1, wherein the drive motor and the lead screw are both positioned with respect to the base. 4. A first base portion and a second base portion having a two-step structure are formed on the base, and the gear train is provided in a space between the first base portion and the second base portion. The lens according to claim 3, wherein the lead screw is rotatably supported by the first base portion, and the drive motor is fixed by the second base portion. Drive. 5. The second base portion has a fitting hole into which a part of the main body of the drive motor is fitted, and a notch that cuts out a part of the fitting hole to allow an output shaft of the drive motor to pass therethrough. 5. The lens drive device according to 4, further comprising: