JPH09145981A - Lens driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the driving precision by arranging a V-shaped roller which engages with the V-shaped cam groove of a cylindrical cam at each projection part formed on a driven lens group and making the angle of the V shape of the cam groove acuter than that of the V shape of the roller. SOLUTION: The cylindrical cam 6 which has V-shaped cam grooves 7 and 7 is provided between support plates 3a and 3a of a fixed frame 3 and can be driven by a driving source 4. Further, V-shaped rollers 9 and 9 are fitted to shaft parts 8a and 8a provided on projection parts 8a and 8 of both lens holding frames 1 and 1, and engaged with the cam grooves 7 and 7. Here, the angle of the V shapes of the rollers is made acuter than that of the V shapes of the cam grooves. The rollers 9 and 9 are pressed against the cam grooves 7 and 7 of the cylindrical cam 6 by elastic materials 10 and 10 and the rollers securely abut against the wall surfaces of the cam grooves of the cylindrical cams, and the rollers 9 and 9 which engage with the cam grooves 7 and 7 securely follow up the cylindrical cams as the cams rotate and the lens holding frames 1 and 1 move along the guide shafts 2 and 2 with high precision.

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, and more particularly, to a lens driving device in which a V-shaped cam groove of a cylindrical cam and a V-shaped roller provided integrally with each lens group are engaged with each other. It is about.

[0002]

2. Description of the Related Art Conventionally, a variable power lens group consisting of at least two lens groups for changing the magnification and a correction lens group for correcting the focal position are arranged parallel to the optical axis. As a zoom lens device that is driven by the opened cylindrical cam, a lens driving device shown in FIG. 7 is known.

In the lens driving device shown in FIG. 7, there are two lens holding frames 31, 31 for holding a lens group, and two guide shafts 32 penetrating them and facing each other with an optical axis interposed therebetween. It is held in the fixed frame 33 by 32. On the other hand, a cylindrical cam 36, which is provided in parallel with the optical axis and is rotationally driven by a drive source 34 via gears 35, 35, has an outwardly U-shaped cam groove 37 formed on its peripheral surface. There is.

Rollers 39, 39 are provided on the protrusions 38, 38 integrally formed on the lens holding frames 31, 31 so as to be rotatable in the direction parallel to the optical axis.
9 and 39 are the cam grooves 37 and 3 of the U-shape facing outward, respectively.
7 is engaged with the wall surface. Therefore, the drive source 34
Is transmitted to the cylindrical cam 36 via the gear 35, and the cylindrical cam 36 rotates.

The rollers 39, 39 provided on the projections 38, 38 integrally formed with the lens holding frames 31, 31 for holding the lens group are located in the cam grooves 37, 37, so that the cam grooves 37, 37 are provided. , 37 along both lens holding frame 3
1, 31, that is, the lens group moves.

In the lens driving device constructed as described above, in order to improve the driving accuracy of the lens, the cam groove of the metal cylindrical cam is machined with a high processing accuracy to form an outward U-shape. It is also necessary to improve the accuracy of the roller provided on the protruding portion of the lens holding frame and located inside the cam groove.

[0007] Therefore, the manufacturing cost of the cam groove becomes high because the cutting process with high accuracy is required, and the driving accuracy is about 1.4 times as much as the play between the cam groove and the roller in the optical axis direction. There was a problem that occurs.

It is conceivable to manufacture a cylindrical cam with a molded product in order to reduce the manufacturing cost. However, since the cam groove is U-shaped outwardly, a part of the cam groove is undercut, Therefore, it could not be manufactured as a molded product.

That is, in general, as a difficulty in manufacturing a cylindrical cam by molding, when the outwardly U-shaped cam groove 37 having a developed shape as shown in FIG. 8 is formed as shown in FIG. It is necessary to use a split mold as a mold and further divide the split mold into two or more. Note that FIG. 10 shows a case of three divisions (a, b, c). However,
When the shape of the cam groove is an outward U-shape, the portion shown in FIG. 11 is undercut, and the axial portion becomes 90 ° with respect to the split direction, so the split mold comes off. (See FIG. 12) On the one side wall surface of the off-axis cam groove, θ1 is apparently 90 ° or more, which causes an overhang, so the split mold cannot be removed (see FIG. 13).

Therefore, it is impossible to manufacture the cylindrical cam 36 in which the cam groove 37 has an outwardly U-shape.

The present invention solves the above-mentioned problems of the conventional ones, the cam groove shape is V-shaped, the lens holding frame is provided with a V-shaped roller, and the angle of the roller is larger than the angle. The drive accuracy can be improved by making the angle of the cam groove an acute angle and elastically engaging this roller in the cam groove, and even if there is a manufacturing error in manufacturing the cylindrical cam, it is not affected. It is an object of the present invention to provide a lens driving device that can obtain high driving accuracy.

[0012]

In order to achieve the above-mentioned object, the present invention comprises a variable power lens group for changing the magnification and a correction system for correcting the focal point position, which is composed of at least two lens groups. In a zoom lens device in which a lens group is driven by a cylindrical cam placed in parallel with an optical axis, a cam groove of the cylindrical cam is formed in a V shape, and a projecting portion integral with the driven lens group is formed. A V-shaped roller, which is formed and is engaged with the cam groove by an elastic material while being pressed by the elastic material, is arranged, and the V-shaped angle of the cam groove is set to be larger than the V-shaped angle of the roller. Also has a configuration with an acute angle. Further, the cylindrical cam having the V-shaped cam groove has a structure manufactured by molding.

[0013]

Since the present invention is constructed as described above, the roller provided in the lens holding frame of the lens group is positioned in the cam groove provided in the cylindrical cam while being pressed by the elastic member, and The wall surface contacts the roller. In this case, since the cam groove and the roller each have a V-shape, and the V-shaped angle of the cam groove is more acute than the V-shaped angle of the roller, how the cam groove changes. Even if it does not come off, the roller moves reliably along the cam groove, the lens group is moved, and the movement accuracy of the lens group can be improved. Further, since the cam groove of the cylindrical cam is formed in a V shape, it can be manufactured by molding.

[0014]

DETAILED DESCRIPTION OF THE INVENTION A lens driving device according to the present invention shown in the drawings will be described below. 1 and 2 show a lens driving device according to the present invention. FIG. 1 is a schematic cross-sectional view of the lens driving device, and FIG. 2 is a roller of a projecting portion integrally provided on a lens holding frame of FIG. And V of cylindrical cam
It is a schematic sectional drawing which shows the relationship with a V-shaped cam groove.

In the lens driving device according to the present invention, two guide shafts 2, 2 sandwiching the optical axis are provided inside a fixed frame 3, and two lens holdings are provided with the guide shafts 2, 2 penetrating. The frames 1 and 1 are attached so as to be movable in the optical axis direction. Further, a cylindrical cam 6 having V-shaped cam grooves 7, 7 is provided between the support plates 3a, 3a integrally provided opposite to the outer side of the fixed frame 3 so as to face the optical axis direction. The cam 6 can be rotationally driven by the drive source 4 and the gear 5 provided on the one support plate 3a side.

Protrusions 8 and 8 are integrally provided on the upper portions of both lens holding frames 1 and 1, and shafts 8a oriented orthogonal to the optical axis are provided on the protrusions 8 and 8.
8a is provided, and elastic members 10, 1 are attached to the shaft portions 8a, 8a.
0 and a V-shaped roller 9 having an inclined upper surface are attached, and locking fittings 11 are attached to the upper end. Although the V-shaped rollers 9 and 9 configured as described above engage with the V-shaped cam grooves 7 and 7, the V-shaped angle of the cam groove is smaller than the V-shaped angle of the rollers 9 and 9. One is formed with an acute angle.

In the normal state, the rollers 9, 9 are made of the elastic material 1.
0, 10 are pressed outward, that is, in the direction of the V-shaped cam grooves 7, 7 of the cylindrical cam 6, and at least some of the rollers 9, 9 are cam grooves 7 of the cylindrical cam 6. , 7 inside, the roller reliably contacts the wall surface of the cam groove of the cylindrical cam, which is affected even if an error occurs in the cam groove 7 during manufacturing. There is no such thing.

Therefore, the cylindrical cam 6 by the drive source 4
In accordance with the rotation of the lens holding frame 1, the rollers 9, 9 engaged with the cam grooves 7, 7 follow the lens holding frame 1 for holding the lens group.
1 reliably moves along the guide shafts 2 and 2 to perform highly accurate movement.

When the cylindrical cam 6 is manufactured as a molded product, the cam groove 7 is V-shaped as shown in FIG. 3, and the mold shown in FIGS. 9 and 10 is shown in FIG. In the case of four divisions (a, b, c, d) as described above, θ 1
Both θ2 are 90 ° or less, and the split mold can be removed without overhang (see FIGS. 5 and 6).

Therefore, if the cam groove 7 is V-shaped, it is possible to manufacture the cylindrical cam 6 by molding.

As described above, the cylindrical cam having the V-shaped cam groove is used, and the V-shaped roller engaged in the cam groove is pressed into the cam groove by the elastic material and the cam groove V
Since the angle of the V-shape is made more acute than the angle of the V-shape of the roller, the surface of the roller surely contacts the wall surface of the cam groove. Therefore, even if there is an error in manufacturing the cylindrical cam, it is not affected at all, and the lens holding frame, that is, the lens group, moves along the shape of the cam groove of the cylindrical cam when the drive source is driven. However, this means that the roller can be reliably tracked and the lens group can be moved to an appropriate position no matter how the inclination of the cam groove changes.

When the rollers are in contact with both wall surfaces of the cam groove, the roller rotates in the direction of rotation along one wall surface and slides on the other wall surface, or It may slide on both walls of the cam groove without rotating. Further, when the roller is in contact with only one wall surface of the cam groove, the roller comes into contact with the surface of the cam groove on the front side in the moving direction of the lens holding frame and rotates together.

Further, as described above, even when the cylindrical cam is manufactured as a molded product and this cylindrical cam is used, there is no influence on the manufacturing error and the shape of the cam groove is changed. Along with this, the lens holding frame, that is, the lens group moves, so that the roller can reliably track and move the lens group to the proper position no matter how the inclination of the cam groove changes. You can

[0024]

As described above, the present invention has at least 2
A zoom lens device in which a variable magnification lens group for changing the magnification and a correction lens group for correcting the focal position are driven by a cylindrical cam placed parallel to the optical axis. The cam groove of the cylindrical cam is formed in a V shape to form an integral projection on the driven lens group, and each projection is engaged with the cam groove while being pressed by the elastic member. Since a V-shaped roller is provided and the V-shaped angle of the cam groove is made more acute than the V-shaped angle of the roller, the surface of the roller surely abuts the wall surface of the cam groove,
Even if there is an error in manufacturing the cylindrical cam, it is not affected at all. Then, when the drive source is driven, the lens holding frame, that is, the lens group, moves along the shape of the cam groove of the cylindrical cam. This means that the roller does not change regardless of how the inclination of the cam groove changes. This has the effects that the tracking can be performed reliably, the lens group can be moved to an appropriate position, errors in the optical axis direction can be reduced, and movement accuracy can be improved.

Even when the cylindrical cam having the V-shaped cam groove is manufactured by molding, the roller located in the cam groove is pressed against the cam groove by the elastic material.
The lens group provided with the rollers can be reliably moved along the cam groove to be moved to an appropriate position, and the movement accuracy can be improved and the manufacturing cost can be reduced. doing.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a lens driving device according to the present invention.

FIG. 2 is a schematic cross-sectional view showing a relationship between a roller of a protruding portion integrally provided on the lens holding frame shown in FIG. 1 and a V-shaped cam groove of a cylindrical cam.

FIG. 3 is a schematic explanatory view showing a V-shaped cam groove of a cylindrical cam.

FIG. 4 is a schematic explanatory view showing a split type.

FIG. 5 is a schematic explanatory view showing a state in which the split mold is removed from the axial portion.

FIG. 6 is a schematic explanatory view showing a state in which a split mold is removed from an off-axis portion.

FIG. 7 is a schematic sectional view showing a conventional lens driving device.

FIG. 8 is a schematic explanatory view showing a developed state of a cam groove of a conventional cylindrical cam.

FIG. 9 is a schematic explanatory view showing a split mold in the case of manufacturing a conventional cylindrical cam by molding.

10 is a schematic explanatory diagram showing a state in which the split mold shown in FIG. 9 is further split.

FIG. 11 is a schematic explanatory view showing an outward U-shaped cam groove of a cylindrical cam.

FIG. 12 is a schematic explanatory view showing a state in which the split mold is removed from the axial portion.

FIG. 13 is a schematic explanatory view showing a state in which the split mold is removed from an off-axis portion.

[Explanation of symbols]

 1, 31 ... Lens holding frame 2, 32 ... Guide shaft 3, 33 ... Fixed frame 4, 34 ... Drive source 5, 35 ... Gear wheel 6, 36 ... Cylindrical cam 7, 37 ... Cam groove 8, 38 ... Protruding portion 8a ... Shaft portion 9, 39 ... Roller 10 ... Elastic material 11 ... Locking metal fitting

Claims (2)

[Claims] 1. A variable magnification lens group for changing magnification and a correction lens group for correcting a focal position are driven by a cylindrical cam placed in parallel with an optical axis. In the zoom lens device described above, the cam groove of the cylindrical cam is formed in a V shape, an integral protrusion is formed in the driven lens group, and an elastic material is pressed against the protrusion to the cam groove. The lens driving device is characterized in that a V-shaped roller that engages in a fixed state is provided, and the V-shaped angle of the cam groove is made more acute than the V-shaped angle of the roller. 2. The lens driving device according to claim 1, wherein the cylindrical cam having the V-shaped cam groove is manufactured by molding.