JP2003090949A - Lens driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the structure of a lens driving device simple by decreasing the number of guide shafts, the function of which is only to guide a lens holding member. SOLUTION: The lens driving device is equipped with the lens holding member 30, one guide shaft 40 which guides the lens holding member 30 freely movably in the direction L of an optical axis, and a lead screw 50 which threadably engages a female screw part 35 (nut 35a) provided to the lens holding member 30 to move the lens holding member 30 along the optical axis; and a male screw part 51 and a guide part 52 are formed on the lead screw 50 to give a function as another guide shaft in addition to a function of moving the lead screw 50. Consequently, the number of components is decreased to make the device low-cost and small-sized.

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 guide shaft that guides a member that holds a lens in the optical axis direction and a lead screw that moves the member in the optical axis direction.

[0002]

2. Description of the Related Art As a conventional lens driving device, for example, as shown in FIG. 4, a lens holding member 1 holding a lens G and two pieces for guiding the lens holding member 1 movably in an optical axis direction L. It is known that the guide shafts 2 and 3 of FIG. 1, one lead screw 4 that moves the lens holding member 1 in the optical axis direction L, and a drive motor (not shown) that applies a driving force to the lead screw 4 are known. ing.

That is, the lens holding member 1 has a through hole 1a 'through which one guide shaft 2 is slidably inserted,
Two connecting portions 1a and 1b defining 1b 'and one U-shaped connecting portion 1c defining a U-shaped groove 1c' through which the other guide shaft 3 is slidably formed are integrally formed.
Further, a nut 1e screwed onto the male screw portion 4a of the lead screw 4 is fixed to the protruding portion 1d protruding from the connecting portion 1a.

The lens holding member 1 is prevented from tilting by the two connecting portions 1a and 1b, and the lens holding member 1 is prevented from rotating by the single U-shaped connecting portion 1c. The lens holding member 4 is moved movably in the optical axis direction L and is moved forward or backward in the optical axis direction L by the rotation of the lead screw 4.

[0005]

However, in the above-mentioned conventional apparatus, the two guide shafts 2 and 3 for guiding the lens holding member 1 in the optical axis direction L and the lens holding member 1 in the optical axis direction. Since one lead screw 4 for moving to L is used, a total of three shafts are required. Therefore, there is a problem in that the size of the apparatus is increased because the cost of the parts is increased and the arrangement space is increased accordingly.

The present invention has been made in view of the above points, and it is an object of the present invention to reduce the number of parts, the cost, the size of the device, and the like by using the lens holding member as an optical member. It is an object of the present invention to provide a lens driving device that can be accurately positioned, guided, and moved in the axial direction.

[0007]

A lens driving device of the present invention is provided on a lens holding member for holding a lens, guide means for movably guiding the lens holding member in the optical axis direction, and the lens holding member. A lens driving device comprising: a lead screw that is screwed into the female screw portion to move the lens holding member in the optical axis direction, wherein the guide means includes two guide shafts, and the lead screw includes two lead shafts. The feature is that it also serves as one of the guide shafts. According to this configuration, the lead screw also serves as one guide shaft, so that the lens holding member is positioned and guided in the optical axis direction by one lead screw and one guide shaft, and the lens holding member is guided by the lead screw. It can be moved axially. Thus, by using the lead screw also as the guide shaft, the number of parts can be reduced, the cost can be reduced, and the device can be downsized.

In the above structure, the lens holding member has a connecting portion slidably connected to the guide shaft, and the lead screw slides the connecting portion coaxially with the male screw portion which is coaxially engaged with the female screw portion. A configuration having a guide portion that guides movably can be adopted. According to this configuration, since the male screw portion and the guide portion are formed coaxially with the lead screw, for example, the male screw portion is formed in a predetermined range in the axial direction, and the guide portion is formed in the remaining range. can do.

In the above structure, the lens holding member includes
A configuration in which at least two connecting portions are provided can be adopted. With this configuration, it is possible to reliably prevent the lens holding member from tilting and guide the lens holding member in the optical axis direction.

In the above structure, the female screw portion may be arranged next to at least two connecting portions continuously arranged in the optical axis direction. According to this configuration, since the connecting portion is continuously formed and the female screw portion is continuously formed on the outer side of the connecting portion, for example, a lead screw having a guide portion having a small outer diameter and a male screw portion having a large outer diameter,
When connecting to the connecting part and female screw part of the lens holding member,
First, the guide part having a small outer diameter is inserted into the female screw part, then the connecting part, and then the male screw part having a large outer diameter is screwed into the female screw part to thereby connect the lead screw and the lens holding member. , Can be connected smoothly.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 3
FIG. 1 shows an embodiment of a lens driving device according to the present invention, FIG. 1 is a side sectional view showing the entire device, and FIGS. 2 and 3 are perspective views showing a guide shaft, a lead screw, and a lens holding member. FIG.

As shown in FIGS. 1 to 3, this lens driving device serves as a reference for mounting various parts, and a cover 2 coupled to the base 10 and covering the whole.
0, the lens holding member 30, one guide shaft 40 for guiding the lens holding member 30 in the optical axis direction L, one lead screw 50 for moving the lens holding member 30 in the optical axis direction L, and rotation to the lead screw 50 A drive mechanism 60 that exerts a force is provided.

The base 10 includes a back plate 11 and a back plate 11
Is formed so as to define a substantially rectangular frame portion 12 formed in a substantially central portion. A fitting hole 11 for fitting and fixing one end portion of the guide shaft 40 in the back plate portion 11.
a, a bearing hole 11b for rotatably supporting one end of the lead screw 50, and the like are formed. A face plate 13, a CCD 14 as an image sensor, and the like are arranged in the frame portion 12.

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 flange portion for fixing a step motor 61 described later is formed on the side surface thereof. 22 is integrally formed. A fitting hole 23 for fitting and fixing the other end of the guide shaft 40 and a bearing hole 24 for rotatably supporting the other end of the lead screw 50 are formed on the front wall surface of the cover 20. Has been done.

As shown in FIG. 1, the lens holding member 30 includes lenses G1, which are sequentially arranged in the optical axis direction L.
A tubular portion 31 that holds G2, G3, G4, and G5, 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, and a plate-shaped portion 32.
A first connecting portion 33 continuously connected to the lead screw 50, a second connecting portion 34, a female screw portion 35 to which a nut 35a is fixed, and a U-shaped connecting portion 36 connected to the guide shaft 40, And the like.

Here, the first connecting portion 33 and the second connecting portion 3
4, through holes 33a, 34a having a circular cross section with a diameter smaller than the inner diameter of the female screw 35a 'of the nut 35a are formed, and the female screw portion 35 has a circular shape with a diameter larger than the inner diameter of the female screw 35a'. A through hole 35 'having a cross section is formed.

As shown in FIG. 1, one end of the guide shaft 40 is fitted into a fitting hole 11a formed in the back plate 11 (base 10), and the other end thereof is covered with the cover 2.
It is fitted in a fitting hole 23 formed in 0 and is fixed at a predetermined position between the base 10 and the cover 20. The guide shaft 40 is inserted into the U-shaped groove 36a formed in the U-shaped connecting portion 36 to guide the lens holding member 30 slidably in the optical axis direction L.

As shown in FIGS. 2 and 3, one end of the lead screw 50 is inserted into the bearing hole 11b of the back plate 11 (base 10) and the other end thereof is inserted into the bearing hole 24 of the cover 20. Thus, it is rotatably supported at a predetermined position between the base 10 and the cover 20. Further, the lead screw 50 has a male screw portion 5 on a part of its outer peripheral surface.
1, a guide portion 52, etc. are formed, and a second gear 63, which will be described later, is fixed to a shaft portion 53 located axially outside the male screw portion 51.

Here, as shown in FIG.
The outer diameter D1 of the guide portion 52 is larger than the outer diameter D2 of the guide portion 52. Further, the male screw portion 51 is configured such that the female screw 35a 'of the nut 35a is smoothly screwed, and is formed smaller than the inner diameter of the through hole 35'. Further, the guide portion 52 includes the first connecting portion 33 and the second connecting portion 33.
It is formed so as to be slidably inserted into the through holes 33a, 34a of the connecting portion 34 in a close contact state.

Therefore, when the lead screw 50 is connected to the lens holding member 30 to be assembled, first,
The guide portion 52 having the smaller outer diameter D2 is first passed through from the nut 35a side, and then passed through the through hole 34a of the second connecting portion 34 and then the through hole 33a of the first connecting portion 33. As a result, the lead screw 50 is guided in the insertion direction with the outer peripheral surface 52 'of the guide portion 52 being in close contact with the inner peripheral surfaces of the through holes 34a, 33a. Then, when the male screw portion 51 collides with the end surface of the nut 35a, the male screw portion 51 is screwed into the nut 35a while rotating the lead screw 50, and the assembling of both is completed.

As described above, in the optical axis direction L, the female screw portion 35 (nut 35a) is positioned next to the two consecutively arranged connecting portions (the first connecting portion 33 and the second connecting portion 34). As described above, that is, since the first connecting portion 33, the second connecting portion 34, and the female screw portion 35 are sequentially arranged in the optical axis direction L, the guide portion 52 having the small outer diameter D2 and the large outer diameter as described above. The lead screw 50 having the male screw portion 51 of D1 is attached to the first connecting portion 33 and the second connecting portion 34 (through holes 33a, 34a) having a small inner diameter D2 and the female screw portion 35 (nut 35a) having a large inner diameter D1. When connecting, the lead screw 50 and the lens holding member 30 can be easily connected only by inserting the lead screw 50 from one direction and rotating it.

By being connected in this way, the guide portion 52 of the lead screw 50 is connected through the two connecting portions (the first connecting portion 33 and the second connecting portion 34).
The lens holding member 30 is slidably guided in the optical axis direction L while preventing the inclination. Further, the male screw portion 51 of the lead screw 50 is replaced by the female screw portion 35 (nut 35a).
The lens holding member 30 is moved in the optical axis direction L via. That is, the lead screw 50
Not only moves the lens holding member 30, but also serves as a guide shaft for guiding in the optical axis direction L.

As described above, the single lead screw 50 inserted into the first connecting portion 33 and the second connecting portion 34 prevents the lens holding member 30 from tilting, and also the U-shaped connecting portion 36.
The one guide shaft 40 connected to prevents the lens holding member 30 from rotating, and guides the lens holding member 30 while positioning it in the optical axis direction L with high accuracy. Ie 1
Book guide shaft 40 and one lead screw 50
By these, guide means for movably guiding the lens holding member 30 in the optical axis direction L is configured.

In this way, the lead screw 50 also serves as a guide shaft, so that the number of original guide shafts can be reduced accordingly. As a result, the cost can be reduced by reducing the number of parts, and the device can be downsized by reducing the arrangement space.

As shown in FIG. 1, the drive mechanism 60 is fixed to the lead screw 50 so as to mesh with the step motor 61, the first gear 62 fixed to the output shaft 61a of the step motor 61, and the first gear 62. It is formed by the second gear 63 and the like. As shown in FIG. 1, the step motor 61 is placed on a flange portion 22 formed integrally with the cover 20, and a fitting portion 61b is fitted into a fitting hole 22a of the flange portion 22 to be positioned and a desired screw is formed. Etc. are fastened and fixed.

In this state, the output shaft 61a of the step motor 61 is substantially parallel to the optical axis direction L and is arranged in parallel with the lead screw 50. Therefore, the size in the optical axis direction L becomes shorter and the apparatus can be made thinner than that of a structure in which the output shaft 61a of the step motor 61 and the lead screw 50 are aligned. Further, by interposing the first gear 62 and the second gear 63, the output shaft 61a can be connected to the lead screw 5
The reduction ratio up to 0 can be appropriately selected as an arbitrary value,
Even if the screw pitch of the lead screw 50 is not reduced, the movement pitch (resolution during driving) of the lens holding member 30 can be reduced and fine adjustment can be performed.

Next, the operation of the lens driving device will be described. First, when the step motor 61 rotates, the lead screw 50 is rotated via the output shaft 61a, the first gear 62, and the second gear 63. Then, the lens holding member 30 is moved in the optical axis direction L by screwing the male screw portion 51 and the female screw portion 35 together.

At this time, the lens holding member 30 is guided in the optical axis direction L with high accuracy by the guide portion 52 of the lead screw 50 and the guide shaft 40 preventing tilting and rotation. Then, when the lens holding member 30 moves rearward in the optical axis direction L, the home position of the detected plate (not shown) and the photo interrupter (not shown) formed integrally with the lens holding member 30. Is detected and the movement is stopped.

On the other hand, when the step motor 61 rotates in the reverse direction, the lead screw 50 rotates in the reverse direction, and the lens holding member 30 is moved forward in the optical axis direction L. Also at this time, as in the above, the lead screw 5
The zero guide portion 52 and the guide shaft 40 guide the lens holding member 30 in the optical axis direction L with high accuracy while preventing tilting and rotation. In this way, by the movement of the lens holding member 30 in the optical axis direction L, a zooming operation, a widening operation, or the like with respect to the imaging surface of the CCD 14 is performed.

In the above embodiment, the two connecting portions 33 and 34 are shown as the connecting portions to be connected to the guide portion 52 of the lead screw 50. However, the connecting portions are not limited to this, and one connecting portion may be used. By adopting this, the screwed state of the female screw portion 35 (nut 35a) and the male screw portion 51 may be managed with high accuracy, and the female screw portion 35 (nut 35a) may serve as a connecting portion. Further, the number of connecting portions is not limited to two, and three or more connecting portions may be adopted. Further, although the nut 35a is fixed as the female screw portion 35, the present invention is not limited to this, and the through hole 35 'of the female screw portion 35 is not limited to this.
A female screw may be formed directly on the.

In the above embodiment, the through holes 33a and 34a are formed in the first connecting portion 33 and the second connecting portion 34, and the guide portion 52 of the lead screw 50 is inserted through the lead screw 50. If the axial distance between the guide shaft 40 and the guide shaft 40 is managed with high accuracy, a U-shaped groove may be formed in both the connecting portions 33 and 34 in the same manner as the U-shaped connecting portion 34. In this case, the male screw part 5
Even if the guide portions 52 are formed on both sides of the first screw and the first connecting portion 33 and the second connecting portion 34 are formed on both sides of the female screw portion 35, the lead screw 50 and the lens holding The member 30 can be easily connected.

Further, in the above-mentioned embodiment, the guide means according to the present invention is adopted in the device provided with one lens holding member 30, but the present invention is not limited to this, and the device provided with a plurality of lens holding members. Even in
Similarly, the present invention can be adopted.

[0033]

As described above, according to the lens driving device of the present invention, the lead screw is also used as one of the guide shafts for movably guiding the lens holding member in the optical axis direction. The number of points can be reduced, the cost can be reduced, and the size of the device can be reduced by reducing the installation space.

Particularly, by forming the male screw portion and the guide portion on the lead screw and adopting at least two connecting portions connected to the guide portion, the lens holding member can be surely prevented from tilting and the optical axis direction. Can be guided to. Furthermore, when arranging at least two connecting portions and female screw portions formed on the lens holding member, by arranging the female screw portion next to the continuously arranged connecting portion, the lead screw and the lens holding member are arranged. Can be easily connected.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a lead screw, a guide shaft, and a lens holding member which form the lens driving device shown in FIG.

3 is a side sectional view showing a lead screw, a guide shaft, and a lens holding member which constitute the lens driving device shown in FIG.

FIG. 4 is a perspective view showing a lead screw, a guide shaft, and a lens holding member in a conventional lens driving device.

[Explanation of symbols]

G1, G2, G3, G4, G5 Lens L Optical axis direction 10 Base 11a Fitting hole 11b Bearing hole 20 Cover 23 Fitting hole 24 Bearing hole 30 Lens holding member 33 First connecting portion 34 Second connecting portion 33a, 34a Penetrating Hole 35 Female screw portion 35a Nut 36 U-shaped connecting portion 36a U-shaped groove 40 Guide shaft (guide means) 50 Lead screw (guide means, guide shaft) 51 Male screw portion 52 Guide portion 60 Drive mechanism 61 Step motor 62 First gear 63 Second gear

Front page continuation (51) Int.Cl. ⁷ identification code FI theme code (reference) // H04N 101: 00 G02B 7/04 DF term (reference) 2H044 AJ06 DA02 DD01 5C022 AC42 AC54 AC74 5C024 EX21 EX42

Claims (4)

[Claims] 1. A lens holding member for holding a lens, guide means for guiding the lens holding member so as to be movable in the optical axis direction, and a female screw portion provided on the lens holding member, which is screwed into the lens holding member. A lead screw that moves the holding member in the optical axis direction, and a lens driving device, wherein the guide means includes two guide shafts, and the lead screw also serves as one of the two guide shafts. A lens driving device characterized by the above. 2. The lens holding member has a connecting portion slidably connected to the guide shaft, and the lead screw is coaxial with a male screw portion that is screwed into the female screw portion. The lens driving device according to claim 1, further comprising: a guide portion that slidably guides the connecting portion. 3. The lens driving device according to claim 2, wherein the lens holding member is provided with at least two connecting portions. 4. The lens driving device according to claim 3, wherein the female screw portion is arranged next to the at least two connecting portions continuously arranged in the optical axis direction.