JP2595630Y2 - Optical related member drive - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical member driving device, and more particularly to a structure of a cam follower in an optical member driving device for driving an optical member by a cam and a cam follower.

[0002]

2. Description of the Related Art Conventionally, in an optically related member driving apparatus for driving an optically related member incorporated in a camera or the like, for example, a zoom lens or a focusing lens, a mechanism using a cam and a cam follower is generally used. It's being used. In recent years, along with the digitization of the main body device, there has been developed one in which a minute displacement error of the advance / retreat movement position of the lens or the like affects its optical performance.
Therefore, in the optical-related member driving device, a device that is smaller, lighter, and lower in cost while having higher-precision driving performance will be required in the future.

The structure of a conventional lens driving device, which is the above-mentioned optical-related member driving device, will now be described. The lens driving device shown in the perspective view of FIG. 8 holds a lens of a two-group lens for zooming. The frame is driven via a cam groove and a cam follower. In the device,
Lenses 21 and 22 of the above-described two-group configuration that are optically related members
Are held by lens holding frames 23, 24, respectively, and the lens holding frames 23, 24 are guided through shaft holes of the respective bosses 23a, 24a and cutouts of the bifurcated portions 23b, 24b. , 28 so as to be movable back and forth in the direction of the optical axis O. Note that an image sensor holder 26 for holding the image sensor 25 is fixed to the ends of the guide shafts 27 and 28.

Below the bosses 23a and 24a, cam followers 29 and 29 'having a circular cross section are fixed, respectively. The cam followers 29 and 29 ′ are members having the same shape, and the cam grooves 30 formed in the cam plate 30 are provided.
a and 30b are slidably fitted. In the above-described apparatus, the cam groove is provided on a disk-shaped cam plate rotatably supported by the shaft 31. In addition, the cam groove is provided on a rotatable cam ring having a cylindrical shape. Drive devices provided with are also commonly used.

By rotating the cam plate 30 by a predetermined angle, the cam followers 29, 29 'are driven to move the lens holding frames 23, 24 in the optical axis direction.
However, in order to maintain the slidable state, the cam followers 29, 29 'are slightly larger than the width W of the cam grooves 30a, 30b, as shown in FIG. A diameter D is given which is smaller by a dimension on the order of 1/100 mm. Therefore, the fitting play d is inevitably generated. This play is caused by the lens holding frame 2
It appears as an error between the forward and backward positions of 3, 24. Therefore, in order to eliminate the above-mentioned fitting play, in the present device, the springs 32, 3 are attached to the bosses 23a, 24a of the lens holding frames 23, 24.
3 and urge the lens holding frames 23 and 24 in a predetermined direction. Then, the cam followers 29, 29 'are
In this configuration, the backlash is removed by contacting the reference surfaces 0a and 30b with each other. FIG. 10 shows the urging force F of the springs 32 and 33.
Thus, the cam followers 29 and 29 'are in contact with the cam reference surface.

However, in the above-described conventional apparatus, the springs 32, 33 for biasing the cams must be disposed around the lens holders 23, 24, and there is a space problem. Further, the rotational load of the cam plate 30 varies depending on the advancing and retreating positions of the lens holding frames 23 and 24, which is not preferable in terms of motor driving characteristics. Furthermore, man-hours for suspending the spring were also required.

In order to solve these problems, a lens moving mechanism using a cam groove disclosed in Japanese Patent Application Laid-Open No. 54-91322 has been proposed. In this proposed mechanism, as shown in FIG. 11, a cam follower 49 is an example of the shape of the cam follower of the lens holding frame.
By slitting the cam groove fitting portion, a large thick section 49a and a small elastically deformable small section 49b having a small thickness were formed. However, the cross sections 49a, 4
The outer dimension D 'between the portions 9b is set slightly larger than the width W of the cam groove 30a. The cam follower 49 is fitted into the cam groove 30a. At the time of the fitting, the small cross section 49b is deformed in the direction of the optical axis O and press-fitted (see FIG. 12).

[0008] thus constituted the lens moving equipment to <br/> Oite becomes a cam follower 49a when forward and backward movement of the lens holding frame that can be slid without play on the cam grooves 30a, looseness This allows the lens holding frame to be moved forward and backward without any influence. Further, it is not necessary to dispose the springs 32 and 33 as in the lens driving device of FIG.

[0009]

However, in the lens moving mechanism using a cam groove disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 54-91322, the cam follower 49a is connected to the cam groove 3.
When press-fitting into 0a, only the small cross section 49b is deformed, so that the center position of the cam follower 49 and the center of the cam groove 30a do not always coincide with each other due to variations in the groove width and the dimensions of the cam follower. FIG.
FIG. 5 is a plan view showing a sliding state with respect to the cam groove 30a in the engaged state. Actually, the cam plate 30 rotates,
Although the cam follower 49 fixed to the lens holding frame moves forward and backward only in the direction of the optical axis O, in FIG. 13, the cam plate 30 is shown as being fixed, and each of the cam followers 49 is positioned on the optical axis OT. Position 49 (A), standard position 49 (B) on optical axis OS, wide position 49 on optical axis OW
(C) is shown as having relatively moved. As shown in the figure, the cam groove 30a is formed along the locus of the outer diameter C of the cutter 12. The locus of the center line L1 of the cutter 12 becomes the locus of the center of the cam follower according to the design specifications.

However, since the large cross section 49a actually slides in contact with the reference surface of the cam groove 30a, the center line of the cam follower passes through the locus L2. The trajectory L2 and the center line L1 of the cutter 12 are displaced eT on the optical axis OT, eS on the optical axis OS, and eS due to an error in the processing width of the cutter 12 and an error in the outer dimensions of the cam follower 49.
A shift eW on W may occur. Therefore, the advancing / retracting position of the photographing lens is different from the advancing / retracting position in design, and it is difficult to satisfy the design specification. When the cam plate 30 is a molded part, the error in the processing width of the outer diameter C of the cutter 12 corresponds to the variation in the product size of the molded article. The cam follower is inserted into the cam groove.
The method has not been devised to facilitate the insertion.
won.

The present invention has been made in order to solve the above-mentioned problem, and a pair of elastic forces act on the cam follower itself substantially along the optical axis direction of the optically related member so that the center of the cam follower is set at the target of the cam. An optical-related member driving device that is configured to move on a track without play, does not require a spring for biasing a cam follower, has high accuracy, can be downsized, and is easy to assemble. The purpose is to provide.

[0012]

SUMMARY OF THE INVENTION An optical-related member driving device according to the present invention comprises a rotatable flat cam plate and a cam follower.
Optically related member driving device for driving optically related members
The width of the cam groove at the end of the cam groove of the cam plate.
With a larger relief, and with the rotation of the cam plate
The cam follower moves along the optical axis of the taking lens
The elastic force acts on the lens itself in the direction of the optical axis of the taking lens.
At least a pair of elastic portions for
After the part is inserted into the relief part, it
The center of the muf follower moves on the target track of the cam groove.
It is characterized by having comprised so that it might be.

Another optical-related member driving device according to the present invention.
Drives the optical components by the cam and the cam follower.
Cam follower itself
The elastic force along the optical axis direction of the optical member.
And at least a pair of elastic portions for
A rigid portion is provided at the center of the pair of elastic portions, and the pair of elastic portions is
The center of the cam follower is engaged with the cam groove
Features to move on the target orbit
And

[0014]

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 perspective view of a lens driving device as an optical member driving device according to an embodiment of the present invention. The apparatus of this embodiment is an optically related member that drives a lens holding frame of a two-group lens for zooming via a cam follower by a cam groove. The configuration other than the cam follower is shown in FIG. It has the same configuration as the conventional lens driving device shown.

As shown in FIG. 1, the cam followers 9,
9 'is fixed below the bosses 23a, 24a of the lens holding frames 23, 24 holding the lenses 21, 22 as optically related members. The cam followers 9, 9 'are members having the same shape, and are slidably fitted in cam grooves 10a, 10b provided in a cam plate 10 rotatably supported on a shaft 11. However, the cam follower 9,
9 'are cam grooves 10a, 10a as shown in the perspective view of FIG.
b into the central part 9 by two parallel slits.
a and leaf portions 9b and 9c. The central portion 9a forms a rigid portion, and the leaf portions 9b, 9c
Forms a pair of elastic portions that can be elastically deformed in a direction orthogonal to the slit direction, that is, in the optical axis O direction in the mounted state.
The outer dimension D1 in the direction in which the elastic deformation occurs is determined by the cam groove 10
It is assumed that the width W is slightly larger than the width W of a and 10b by the press-fitting allowance 2 · S (see FIG. 3).

FIG. 3 is a view showing a deformed state when the cam followers 9, 9 'are pressed into the cam grooves 10a, 10b. As shown in this drawing, the leaf portions 9b and 9c of the cam followers 9 and 9 'are each deformed by the dimension S and have a groove width W.
Are press-fitted into the cam grooves 10a and 10b. The outer shape of the leaf portions 9b and 9c has an arc shape having a radius equal to 1/2 of the cam groove width W.

The cam followers 9 and 9 'are held in a state where the slits are fixed to the lens holding frames 23 and 24 in a direction perpendicular to the optical axis O direction. Then, as shown in the plan view of the cam groove fitting state of FIG. 4, the cam plate 10 is press-fitted into the side surfaces of the cam grooves 10a and 10b. As a press-fitting method, the cam plate 10 is rotated clockwise, and the wide relief portions 10c and 10d provided on the leaf portion of the cam groove are positioned on the optical axis O.
Then, the cam followers 9, 9 'are connected to the escape portions 10c, 10'.
Insert into d once. Thereafter, when the cam plate 10 is rotated counterclockwise, the cam followers 9, 9 'are pressed into the lens frame driving state as shown in FIG.

In the lens driving apparatus of the present embodiment having the above-described configuration, if the state shown in FIG. 4 is a standard state for zooming, the cam plate 10 is moved from this state in the T direction or the W direction. When rotated, the cam follower 9,
9 'is not loose by the cam grooves 10a and 10b, and the optical axis O
Driven in the direction. Then, each lens holding frame 23, 24
Move to the tele position or the wide position along the guide shafts 27 and 28, respectively.

FIG. 5 is a diagram showing an operation state of the cam follower 9 with respect to the cam groove 10a at that time. Since the same applies to the cam follower 9 ', only the cam follower 9 will be described here. As described in FIG. 13, the cam plate 10 actually rotates, and the cam follower 9 fixed to the lens holding frame moves forward and backward only in the optical axis O direction. In FIG. 5, a cam plate 10 is shown as being fixed, and a cam follower 9 has a telephoto position 9 (A) on the optical axis OT and a standard position 9 on the optical axis OS, respectively.
(B), it is shown as having moved to the wide position 9 (C) on the optical axis OW. As shown in this drawing, the cam groove 10a is formed by the locus of the outer diameter C of the cutter 12, and the locus of the center line L1 of the cutter 12 becomes the locus of the center of the cam follower in the design specification as in the case of FIG. .

In this embodiment, the elastic deformation dimensions S (see FIG. 4) of the leaf portions 9b and 9c due to the press-fitting engagement of the cam follower 9 are substantially the same. , Center point PT at wide position, P
S and PW pass through the center line L1 of the cutter 12. Therefore, the advancing / retracting position of the lens coincides with the advancing / retracting position in the design, and the lens drive satisfying the design specification can be executed without any backlash.

Further, according to the lens driving device of the present embodiment, it is not necessary to dispose a backlash removing spring around the lens holding frame as used in the above-mentioned conventional example, and the number of parts and the number of assembling steps can be reduced. At the same time, the space for disposing the spring is not required, and the size can be reduced. Moreover,
Since the cam drive load does not change much with respect to the lens drive position, the load on the drive motor is stabilized. Also, when an impact force acts on the lens holding frames 23 and 24 in the present lens driving device, the leaf portions 9a and 9c of the cam follower 9 are deformed to absorb the impact force and are deformed by a predetermined amount or more. Since the cam follower 9 works as a rigid body, the impact resistance against falling or the like is high.

Next, a description will be given of a modification of the cam follower used in the lens driving device of the above embodiment. FIG. 6 is a perspective view showing the shape of the cam follower of the modification,
The cam follower 15 is formed of an elastic body such as a leaf spring or a rubber member around a central rigid body 15b, and is a leaf part 15 which is an elastic part elastically deformable in the G direction.
a is fixedly formed. The other drive mechanism of the drive device to which the cam follower 15 is applied is the same as that of the above-described embodiment. Also in the case of this modified example, the cam follower 15 is mounted on the lens holding frame such that the G direction is aligned with the optical axis O direction. Further, in this modification, the rigidity of the elastic deformation of the leaf portion 15a can be set to a comparatively arbitrary value, so that the driving load fluctuation is reduced and the elastic deformation dimension is stabilized, so that a more accurate cam drive is performed. It can be performed.

Next, another modified example of the cam follower used in the lens driving device of the above embodiment will be described. FIG. 7 is a perspective view showing the shape of the cam follower of the modification. The cam follower 16 has a leaf portion 1 which is an elastic portion.
The chamfered portions 16e,
16f, and a center portion 16a, which is a rigid portion, is also provided with a chamfered portion 16d on the end face on the cam groove insertion side. However, the diameter of the tip of the chamfered portions 16d, 16e, 16f is smaller than the cam groove width. The height of the central portion 16a is set lower than the leaf portions 16b and 16c so that the leaf portions 16b and 16c can easily fit into the cam grooves. However, the height of the central portion 16a is easier to insert when the height is lowered, and it is not always necessary to set the height lower. The configuration of the other drive mechanism of the drive device to which the cam follower 16 is applied is the same as that of the above-described embodiment. In the present modification, the cam follower 16 is fitted into the cam groove by being guided by the chamfered portions 16e, 16f and 16d, so that the cam follower 16 is very easily assembled. In addition, the relief portions 10c and 10d of the cam groove for inserting the cam follower shown in the above-mentioned embodiment become unnecessary.

[0024]

As described above, the optical-related member driving device of the present invention has the cam follower provided with a pair of elastic portions which can be elastically deformed in the optical axis direction, and the elastic portions are engaged with the side surfaces of the cam groove. The center of the cam follower moves on the target trajectory of the cam groove with high precision without play, so the backlash spring used in the conventional example is provided. The number of parts and the number of assembling steps can be reduced, and at the same time, a space for disposing the spring is not required, so that the apparatus can be downsized and the degree of freedom in design increases. Further, the cam drive load has a number of remarkable effects, such as a change in the drive position with respect to a change in the drive position, which facilitates selection of a drive motor. Also, the cam groove
The cam follower is inserted into the escape part by providing the escape part at the end of
After fitting, it fits into the cam groove.
Is very easy to fit. Also, a pair of cam followers
Elastic part and a rigid part at the center of the pair of elastic parts
Therefore, when an impact force is applied to this device, the pair of elastic parts
It deforms to absorb the impact force, and when it deforms more than a predetermined amount, it becomes rigid.
Because the cam follower acts as a rigid body depending on the body,
The impact resistance against is high.

[Brief description of the drawings]

FIG. 1 is a perspective view of a driving mechanism of a lens driving device which is an optical-related member driving device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a cam follower used in the lens driving device of FIG. 1;

FIG. 3 is a diagram showing a deformed state when a cam follower is fitted into a cam groove of the lens driving device of FIG. 1;

FIG. 4 is a plan view showing an assembled state of a cam follower and a cam groove of the lens driving device of FIG. 1;

FIG. 5 is a diagram showing an operation state of a cam follower on a cam groove at the time of tele, standard, and wide of the lens driving device of FIG. 1;

FIG. 6 is a perspective view of a modification of the cam follower of the lens driving device of the embodiment of FIG. 1;

FIG. 7 is a perspective view of another modification of the cam follower of the lens driving device of the embodiment of FIG. 1;

FIG. 8 is a perspective view of a driving mechanism of a lens driving device showing a conventional example.

FIG. 9 is a view showing a cam groove and a cam follower in the lens driving device of FIG.

FIG. 10 is a diagram showing a state in which a cam follower is urged by a spring and fitted into a cam groove by the lens driving device of FIG. 8;

FIG. 11 is a perspective view of a cam follower used in a lens driving device showing another conventional example.

FIG. 12 is a view showing a fitted state of a cam groove and a cam follower in the lens driving device of FIG. 11;

FIG. 13 shows the telescopic, standard,
The figure which shows the operating state of the cam follower on the cam groove at the time of wide.

[Description of reference numerals] 9, 9 ', 15, 16 ... Cam followers 10a, 10b ... Cam grooves (cams, side surfaces of cam grooves) 9a, 9b, 15a, 16b, 16c ……… Leaf part (a pair of elastic parts) 23, 24 ……………… Lens holding frame (optically related member) O …………… Optical axis

Claims (2)

(57) [Scope of request for utility model registration] 1. A cam plate and a cam follower which are rotatable and flat.
Optically related member driving device for driving optically related members
At the end of the cam groove of the cam plate, a relief larger than the width of the cam groove is provided.
And a photographing lens as the cam plate rotates.
On the cam follower itself that moves along the optical axis of the camera
At least to apply elastic force in the direction of the optical axis of the lens
Also, a pair of elastic parts are provided, and the pair of elastic parts
After inserting the cam follower into the cam follower
Structured so that the center moves on the target track of the cam groove
An optical-related member driving device , characterized in that: 2. An optically related part by a cam and a cam follower.
In the optical member driving device for driving the material, the cam follower itself is disposed along the optical axis direction of the optical member.
At least one pair of elastic parts for applying elastic force
And a rigid part is provided at the center of the pair of elastic parts.
The cam follower by engaging a pair of elastic
So that the center of the waft moves on the target track of the cam groove
An optical-related member driving device, comprising: