WO2010058722A1

WO2010058722A1 - Lens unit

Info

Publication number: WO2010058722A1
Application number: PCT/JP2009/069181
Authority: WO
Inventors: 芳史三谷
Original assignee: コニカミノルタオプト株式会社
Priority date: 2008-11-21
Filing date: 2009-11-11
Publication date: 2010-05-27

Abstract

A lens unit, wherein a follower section and a cam groove are joined to each other via the cam through a linear movement guiding section to allow a movement frame to be moved in the light axis direction along the linear movement guiding section. The follower section is provided with contact surfaces adapted to move while being in contact with side surfaces of the cam groove, and also with auxiliary surfaces provided near the contact surfaces and moving while maintaining gaps relative the side surfaces of the cam groove, the gaps having a magnitude smaller than the magnitude of elastic deformation of the contact surfaces. Because of the configuration, the area of the contact is small in a normal drive condition, and when an impact is applied, the auxiliary contact surfaces make contact with the side surfaces of the cam groove before the contact surfaces are crushed. The configuration increases the area of the contact to reduce drive loss in the normal drive condition and makes the lens unit small in size and highly resistant to impact.

Description

Lens unit

The present invention relates to a lens unit, and more particularly to a lens unit that moves a moving frame that holds a lens system using a linear guide portion, a cam groove, and a follower portion.

Lens units are required to be smaller and lower in cost while maintaining and improving performance such as optical performance, high drive response, and power saving. In addition, due to improved portability due to miniaturization, it is also required to ensure quality in a harsher usage environment.

In order to reduce the size and cost, it is necessary to make the mechanical parts plastic. On the other hand, to secure the performance, it is necessary to minimize the engaging part of the moving body. For example, from the viewpoint of optical performance, if there are many engaging surfaces, it is necessary to take a clearance in order to allow a shape error such as the mutual position accuracy of the contact portions, and the holding accuracy decreases.

In terms of high drive response and power saving, if there are many engagement surfaces, the drive loss increases, causing problems in response and energy saving. In general, a lubricant is applied to the engaging portion, and in that case, it becomes noticeable at low temperatures.

¡Plasticization of mechanical parts contributes greatly to downsizing because complicated shapes can be manufactured at low cost, but there is a problem in strength. For this reason, in a feeding mechanism using a cam ring that is widely used since the rotational drive source can be converted into a straight movement, it has been proposed to increase the strength by, for example, metalizing the cam follower.

Furthermore, in order to make the cam ring plastic, the cam groove shape must be a bottomed inward taper cam, and it is easy to come off when an external force is applied to the cam ring or cam follower. Has been proposed.

For example, Patent Document 1 includes a large-diameter portion that engages a cam follower with a wide cam groove and a small-diameter portion that engages with a narrow linear guide, and a step portion between the large-diameter portion and the small-diameter portion. A method for preventing the cam follower from coming off when the moving frame receives an external force by being caught on the edge of the straight guide.

Further, for example, in Patent Document 2, a lens frame device includes a cam follower having a conical surface portion and an annular portion having an edge formed on the outer periphery, and a first cam that engages and slides only on the conical surface portion of the cam follower. A groove and a second cam groove that is formed in continuation with and engages and slidably contacts with both the conical surface portion and the annular portion of the cam follower, and has an overall width narrower than the first cam groove, and the cam follower has an external force Even if the cam ring tends to deform due to the action of this, a method for preventing the cam ring from coming off by biting the annular part of the cam follower into the second cam groove has been proposed.

JP 2001-42189 A Japanese Patent Laid-Open No. 2002-23036

However, in a metal cam follower, the crushing on the cam groove side is unavoidable, and performance changes with time.

In the method of Patent Document 1, when the moving frame receives an external force, even if the breakage is avoided, the contact portion of the cam follower is crushed and the play is increased, so that the optical performance is deteriorated. The method of Patent Document 2 is effective only when the cam follower is engaged with the second cam groove that is the terminal end of the cam groove, and when the cam follower is engaged with the first cam groove. There is no effect.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a small and highly impact-resistant lens unit that can reduce driving loss during normal driving.

The object of the present invention can be achieved by the following configuration.

1. A cam ring having a cam groove formed obliquely with respect to the optical axis;
A fixed cylinder having a straight guide portion provided parallel to the optical axis;
A moving frame that has a follower part and holds a lens system;
In the lens unit in which the follower portion and the cam groove are cam-coupled via the rectilinear guide portion so that the moving frame is moved in the optical axis direction along the rectilinear guide portion.
The cam groove is formed of a material having higher rigidity than the follower portion,
The follower portion is provided in contact with the groove side surface of the cam groove and in the vicinity of the contact surface, has a gap with the groove side surface, and the contact surface is deformed when the contact surface is deformed. A lens unit comprising an auxiliary surface abutting against the groove side surface.

2. 2. The lens unit according to 1, wherein the contact surface and the auxiliary surface have a level difference equal to or less than an elastic deformation amount of the contact surface.

3. The abutment surface is a part of a conical surface having a predetermined taper angle, and the auxiliary surface is provided adjacent to the abutment surface, and is more grooved than a surface obtained by extending the conical surface of the abutment surface. 3. The lens unit according to 1 or 2, wherein the lens unit is a flat surface separated from a side surface.

4. 4. The lens unit according to 3, wherein the auxiliary surface is provided on both sides of the contact surface.

5. The lens unit according to 3 or 4, wherein the auxiliary surface is configured by a surface having a different taper angle with respect to the contact surface.

6. The groove side surface of the cam groove has a tapered shape, and the contact surface and the auxiliary surface are continuous surfaces having a taper angle larger than the taper angle of the groove side surface. The lens unit described in 1.

7. The lens unit according to any one of 1 to 6, wherein the cam ring is made of a plastic material, and the cam groove is an inwardly tapered cam.

8. The said follower part consists of a plastic material with higher slidability than the material of the said cam ring, and is comprised separately from the said moving frame, The said any one of 1-7 characterized by the above-mentioned. Lens unit.

According to the present invention, the follower portion is provided in the vicinity of the contact surface that moves in contact with the groove side surface of the cam groove, and maintains a gap equal to or less than the elastic deformation amount of the groove side surface and the contact surface. Since the contact area is small during normal driving and the contact surface can be increased before the contact surface is crushed when an impact is applied, the contact area can be increased. It is possible to provide a small and highly impact-resistant lens unit that can reduce driving loss during driving.

It is a schematic diagram which shows the structure of the lens unit of this invention. It is a schematic diagram which shows the structure of 1st Embodiment of a follower part. It is a schematic diagram which shows the structure of 2nd Embodiment of a follower part. It is a schematic diagram which shows the structure of 3rd Embodiment of a follower part.

Hereinafter, the present invention will be described based on the illustrated embodiment, but the present invention is not limited to the embodiment. In the drawings, the same or equivalent parts are denoted by the same reference numerals, and redundant description is omitted.

First, the configuration of the lens unit of the present invention will be described with reference to FIG. 1. FIG. 1 is a schematic diagram showing the configuration of the lens unit of the present invention, and FIG. 1 (a) is parallel to the optical axis of the lens unit. FIG. 1B is a development view of the cam ring.

1A, the lens unit 1 includes a fixed cylinder 10, a cam ring 20, a moving frame 30, a follower section 40, and the like. The fixed cylinder 10 has a rectilinear guide portion 11 provided as a through hole parallel to the optical axis L. The cam ring 20 has a cam groove 21 formed obliquely with respect to the optical axis, and is fitted on the outer peripheral side of the fixed cylinder 10. The cam groove 21 is a bottomed inward taper cam.

The moving frame 30 holds the lens system 50, and the follower unit 40 is provided separately from the moving frame 30, and is attached to the outer peripheral side of the moving frame 30 with a screw 60. The follower portion 40 is fitted into the rectilinear guide portion 11 of the fixed cylinder 10 and is also engaged with the cam groove 21 of the cam ring 20. Although omitted in the figure, the follower portion 40 is assembled by opening the end of the cam groove 21 or making a hole on the cam groove 21 from the outer diameter side of the cam ring.

In FIG. 1 (b), the rectilinear guide portion 11, the cam groove 21 and the follower portion 40 are provided at at least three locations around the optical axis L at positions that divide the circumference into approximately three equal parts. In this configuration, when the cam ring 20 is rotated in the arrow A direction, the follower portion 40 engaged with the cam groove 21 is pushed by the cam groove 21 and is moved in the arrow B direction along the straight guide portion 11. . As a result, the lens system 50 is moved in the direction of the optical axis L, and zooming and focus adjustment are performed.

Here, the cam groove 21 is exemplified as a linear cam-shaped lead cam, but may be a curved variable cam as long as the change in the pressure angle is not large.

Next, a first embodiment of the follower unit of the present invention will be described with reference to FIG. FIG. 2 is an enlarged view of the vicinity of the follower section 40 in FIG. 1B, and is a schematic diagram showing the configuration of the first embodiment of the follower section. FIG. 2A is an enlarged view of the vicinity of the follower section 40. FIG. 2B is an enlarged view around the contact surface 41 of the follower portion 40.

2A, as described above, the follower portion 40 is fitted into the rectilinear guide portion 11 of the fixed cylinder 10 and is also engaged with the cam groove 21 of the cam ring 20. As described above, the cam groove 21 is an inwardly tapered taper cam having a tapered side wall 21a. Therefore, the follower portion 40 is in contact with the inner wall of the rectilinear guide portion 11 at the side surface 45, and is in contact with the side wall 21 a of the cam groove 21 at the contact surface 41. The area of the contact surface 41 is set to be small, and the driving loss during normal driving can be reduced.

In FIG. 2B, auxiliary surfaces 42 are provided on both sides of the contact surface 41 with the side wall 21a of the cam groove 21 of the follower portion 40 at a position lower than the contact surface 41 by a step 41a. . The step 41a between the contact surface 41 and the auxiliary surface 42 is such that, for example, when the impact force is applied to the moving frame 30 due to dropping or the like, and the follower portion 40 is strongly pressed against the side wall 21a of the cam groove 21, The level difference is such that the auxiliary surface 42 starts to contact the side wall 21a of the cam groove 21 while elastically deforming. Strictly speaking, the contact surface 41 and the auxiliary surface 42 are curved surfaces, but they may be formed as flat surfaces because of their small area.

As described above, since the auxiliary surface 42 starts to contact the side wall 21a of the cam groove 21 while the contact surface 41 is elastically deformed, the contact area with the side wall 21a is expanded at a stretch. As a result, the force acting on the material is reduced and the impact force can be received without causing plastic deformation. Therefore, both the side wall 21a and the contact surface 41 of the cam groove 21 can be restored to the original shape without being crushed, and the impact resistance is improved.

It is preferable to use a plastic material for the cam ring 20, and it is more preferable to use a material having a Young's modulus larger than that of the follower portion 40, that is, a high rigidity. On the other hand, the follower portion 40 is preferably a plastic material having high slidability, and is preferably formed separately from the moving frame 30. For example, the cam ring 20 and the moving frame 30 may be formed of PC (polycarbonate) and the follower portion 40 may be formed of POM (polyacetal).

Thus, the rigidity and dimensional stability of the cam ring 20 and the moving frame 30 can be secured, and wear due to sliding with the follower portion 40 can be prevented. Moreover, the loss by sliding of the follower part 40 can also be reduced.

As described above, according to the first embodiment, the cam groove 21 is formed on both sides of the abutting surface 41 of the follower portion 40 while an impact is applied to the follower portion and the abutting surface 41 is elastically deformed. By providing an auxiliary surface 42 having a step 41a that starts to come into contact with the side wall 21a, the contact area is small during normal driving, and when an impact is applied, the auxiliary surface comes into contact before the contact surface is crushed to reduce the contact area. Since the size can be increased, it is possible to provide a lens unit that can reduce a driving loss during normal driving and is small and has high impact resistance.

Next, a second embodiment of the follower unit of the present invention will be described with reference to FIG. 3A and 3B are schematic views showing the configuration of the second embodiment of the follower portion, FIG. 3A is a schematic view showing the shape of the follower portion, and FIG. 3B is a contact between the follower portion and the cam groove. It is a schematic diagram which shows the mode of.

3A, the follower portion 40 has a cylindrical surface 45 that contacts the inner wall of the rectilinear guide portion 11 at the lower portion, and a contact surface 41 that contacts the side wall 21a of the cam groove 21 at the upper portion. . The area of the contact surface 41 is set to be small, and the driving loss during normal driving can be reduced. The contact surface 41 has a curved shape obtained by cutting a part of a conical surface.

On both sides of the contact surface 41, auxiliary surfaces 42 each having a taper angle different from the contact surface 41 are provided. The difference in taper angle between the contact surface 41 and the auxiliary surface 42 is preferably 1 to 2 °. For the following explanation, the counterclockwise side of the contact surface 41 is 42a and the clockwise side is 42b.

3 (b), the cam groove 21 is a variable cam that draws a curve from the upper right to the lower left of the figure, and has a side wall 21a having a taper angle. In the figure, the manner in which the side wall 21a of the cam groove 21 and the contact surface 41 come into contact with each other is shown in three places, upper right, center, and lower left.

In the upper right, the side close to the auxiliary surface 42b of the contact surface 41 is in contact with the side wall 21a with almost line contact. When an impact is applied in this state, the auxiliary surface 42b starts to contact the side wall 21a while the contact surface 41 is elastically deformed, and the contact area with the side wall 21a is expanded at a stretch.

In the center, the center of the contact surface 41 is in contact with the side wall 21a with almost line contact. When an impact is applied in this state, the

auxiliary surfaces

42a and 42b begin to contact the side wall 21a while the contact surface 41 is elastically deformed, and the contact area with the side wall 21a is expanded at a stretch.

In the lower left, the side close to the auxiliary surface 42a of the contact surface 41 is in contact with the side wall 21a with almost line contact. When an impact is applied in this state, the auxiliary surface 42a starts to contact the side wall 21a while the contact surface 41 is elastically deformed, and the contact area with the side wall 21a is expanded at a stretch.

As described above, according to the second embodiment, by providing the auxiliary surface 42 constituted by planes having different taper angles with respect to the contact surface 41, the contact area is small during normal driving, and the impact is reduced. As the contact surface is increased before the contact surface is crushed, the contact area can be increased to reduce the drive loss during normal driving and provide a compact and highly impact-resistant lens unit. can do.

Next, a third embodiment of the follower unit of the present invention will be described with reference to FIG. FIG. 4 is a schematic diagram showing the configuration of the third embodiment of the follower part, FIG. 4 (a) is a schematic diagram showing the shape of the follower part, and FIG. 4 (b) is when the impact of the follower part is applied. It is a schematic diagram which shows the mode of a contact with this cam groove.

4A, the side wall 21a of the cam groove 21 of the cam ring 20 has a taper angle θ1. On the other hand, the contact surface 41 of the follower portion 40 is a conical surface having a taper angle θ2, and θ1 <θ2. Since the side wall 21a of the cam groove 21 and the contact surface 41 have different taper angles, the side wall 21a and the contact surface 41 are almost point contact, and drive loss during normal driving can be reduced.

The auxiliary surface 42 of the follower part 40 is the same surface as the contact surface 41. For convenience, the portion in contact with the side wall 21a is referred to as a contact surface, and the upper and lower surfaces are referred to as auxiliary surfaces.

In FIG. 4B, when an impact is applied to the follower portion 40, the follower portion 40 is pushed up in the direction of arrow C in the figure, and the contact surface 41 and the auxiliary surface 42 of the follower portion 40 are elastically deformed as shown. And pressed against the side wall 21a of the cam groove 21 to change from point contact to surface contact with a large area. Thereby, the impact resistance can be increased.

As described above, according to the third embodiment, the contact surface 41 and the auxiliary surface 42 have a larger taper angle than the side wall 21a of the cam groove 21, so that the contact surface 41 and the auxiliary surface 42 are almost point contact during normal driving. When contact is made and an impact is applied, both the contact surface 41 and the auxiliary surface 42 can be elastically deformed to increase the contact area, so that the drive loss during normal driving can be reduced, and the device is compact and impact resistant. A high lens unit can be provided.

Note that the contact surface 41 of the first and second embodiments described above has a larger taper angle than the side wall 21a of the cam groove 21 as in the contact surface 41 of the third embodiment. Also good. As a result, the contact is almost point contact during normal driving, and when an impact is applied, the auxiliary surface comes into contact before the contact surface is crushed to increase the contact area. It is possible to provide a lens unit that can be reduced and is small and has high impact resistance.

As described above, according to the present invention, the follower portion is provided in contact with the groove side surface of the cam groove and moves near the side surface of the cam groove, and the elasticity of the groove side surface and the contact surface. By providing an auxiliary surface that moves while maintaining a gap equal to or less than the deformation amount, the contact area is small during normal driving, and when an impact is applied, the auxiliary surface comes into contact before the contact surface collapses to increase the contact area. Therefore, it is possible to provide a small and highly impact-resistant lens unit that can reduce a driving loss during normal driving.

It should be noted that the detailed configuration and detailed operation of each component constituting the lens unit according to the present invention can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Lens unit 10 Fixed cylinder 11 Rectilinear guide part 20 Cam ring 21 Cam groove 21a Side wall (of the cam groove 21) 30 Moving frame 40 Follower part 41 Contact surface 41a Level difference 42 Auxiliary surface 42a (Counterclockwise side of contact surface 41) Auxiliary surface 42b (clockwise side of contact surface 41) auxiliary surface 45 (side surface of follower section 40) side surface 50 lens system 60 screw L (lens system 50) optical axis θ1 (side wall 21a) taper angle θ2 ( Taper angle (of contact surface 41)

Claims

A cam ring having a cam groove formed obliquely with respect to the optical axis;
A fixed cylinder having a straight guide portion provided parallel to the optical axis;
A moving frame that has a follower part and holds a lens system;
In the lens unit in which the follower portion and the cam groove are cam-coupled via the rectilinear guide portion so that the moving frame is moved in the optical axis direction along the rectilinear guide portion.
The cam groove is formed of a material having higher rigidity than the follower portion,
The follower portion is provided in contact with the groove side surface of the cam groove and in the vicinity of the contact surface, has a gap with the groove side surface, and the contact surface is deformed when the contact surface is deformed. A lens unit comprising an auxiliary surface abutting against the groove side surface.
2. The lens unit according to claim 1, wherein the contact surface and the auxiliary surface have a level difference equal to or less than an elastic deformation amount of the contact surface.
The abutment surface is a part of a conical surface having a predetermined taper angle, and the auxiliary surface is provided adjacent to the abutment surface, and is more grooved than a surface obtained by extending the conical surface of the abutment surface. The lens unit according to claim 1, wherein the lens unit is a plane separated from a side surface.
The lens unit according to claim 3, wherein the auxiliary surface is provided on both sides of the contact surface.
The lens unit according to claim 3 or 4, wherein the auxiliary surface is configured by a surface having a different taper angle with respect to the contact surface.
The groove side surface of the cam groove has a tapered shape, and the contact surface and the auxiliary surface are continuous surfaces having a taper angle larger than a taper angle of the groove side surface. The lens unit according to 1.
7. The lens unit according to claim 1, wherein the cam ring is made of a plastic material, and the cam groove is an inwardly tapered cam.
8. The follower portion according to claim 1, wherein the follower portion is made of a plastic material having a higher slidability than the material of the cam ring, and is configured separately from the moving frame. The lens unit described.