JPH06258564A - Lens driving mechanism - Google Patents

Abstract

PURPOSE:To prevent loss associated with the sliding of a spring while the backlash gathering of a male type helicoid in an optical axis direction is performed by a spring in a male type helicoid rotating system lens driving mechanism. CONSTITUTION:The male type helicoid 10a formed on the outer periphery of a lens block 10 is screwed in a female type helicoid 12b on a camera body side, and when a driving ring 13 is rotated around an optical axis as center, the lens block rotates at the same angle as the ring 13 and moves in the optical axis direction. The spring for gathering backlash 14 is disposed between the driving ring 13 and the lens block 10. Since the lens block 10 and the driving ring 13 always rotate at the same angle, sliding motion is not caused in the spring 14 at all, and the power loss or the abrasion of the spring associated with the sliding is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helicoid-driving-type lens driving mechanism, and in particular, one helicoid is formed at a fixed position with respect to a camera body, and the other helicoid is screwed to the other helicoid. The present invention relates to an improvement of a lens driving mechanism capable of reducing play in the optical axis direction of the lens block, on the premise of a lens driving mechanism including at least a lens block formed with a helicoid.

[0002]

2. Description of the Related Art It is well known that a photographing lens group is moved in the optical axis direction for focus adjustment and magnification change. As a moving method of the photographing lens group, a cam method using a cam or a helicoid is used. The helicoid method using is widely known.

FIG. 4 shows the principle of the cam system. A cam follower 1a is formed on the film side surface of a lens block 1 in which a photographing lens group is inserted, and the cam follower 1a is a light for a camera body. It is in contact with an inclined cam edge 2 formed in an arc shape around the axis. Therefore, when the lens block 1 is turned around the optical axis, the lens follower 1a moves in the optical axis direction while the cam follower 1a slides on the cam edge 2. Also, 3 is a cam follower 1.
is a leaf spring for press-contacting a with the cam edge 2, and the leaf spring 3
Is a support member 4 in a fixed position with respect to the camera body
It is supported by. In addition, in this cam system, since a three-point support system cam with 120 ° intervals is used to prevent the tilt of the lens optical axis, the rotation angle of the lens block 1 is within 120 ° at maximum, and the amount of extension is If it is large, there is a problem that the inclination angle of the cam edge 2 becomes steep.

Next, FIG. 5 is a cross-sectional view of a helicoid system, in which a male helicoid 6a is formed on the outer periphery of a lens block 6 in which the photographing lens group 5 is inserted. On the other hand, 7
Is a support member at a fixed position with respect to the camera body, and a female helicoid 7a screwed with the male helicoid 6a is formed on the inner periphery of the support member 7. Then,
The lens block 6 is moved in the optical axis direction by turning the lens block 6 in a state where the male helicoid 6a and the female helicoid 7a are screwed together. This helicoid method is superior to the cam method in that the turning angle of the lens block 6 is not limited. However, since the helicoid method generally does not have a pressing spring unlike the cam method, the optical axis must be maintained unless extremely high machining accuracy is maintained. There is a problem that the play in the direction becomes large. Therefore, as shown in FIG. 5, the spring 8 is supported by the flange 7b formed on the inner circumference of the support member 7, and the lens block 6 is biased toward the subject side by this spring 8, or as shown in FIG. As in the case of the cam system described with reference to the camera system, a so-called rattling is performed by urging the lens block 6 in the film surface direction by a leaf spring 9 supported by a camera body (not shown). Are known.

[0005]

As described above, it is conventionally known to use a biasing means such as a spring to stabilize the position of the lens block in the optical axis direction. In the case of the conventional method shown in FIGS. 4 and 5, the spring, which is the urging means in any case, makes a turning motion about the optical axis with reference to the support member in a fixed position with respect to the camera body. Since the urging force is applied to the lens block in the optical axis direction, when the lens block is rotated, both the support member and the spring, the lens block and the spring, or the lens block and the spring, and the support member and the spring are supported. There will always be a sliding movement between them. The sliding motion promotes wear of the spring or causes an increase in the motor load when the driving force for driving the lens block depends on the motor.

[0006]

The present invention has been made in view of these problems, and provides a lens drive mechanism in which a spring for stabilizing a lens block does not cause a sliding motion. The purpose is to do.

In summary, the lens drive mechanism of the present invention is:
On the premise of a lens drive mechanism including at least one helicoid formed at a fixed position with respect to a camera body, and a lens block formed with the other helicoid screwed to the one helicoid; A drive ring for turning the lens block by turning at the same turning angle is provided, and a biasing means for applying a biasing force in the optical axis direction to the lens block with the drive ring as a reference is provided. It is what

[0008]

That is, according to the lens driving mechanism of the present invention, one end of the spring for stabilizing the lens block is in contact with the lens block, but the other end is the lens. Since the spring comes into contact with the drive ring that turns together with the block, the spring does not make a sliding motion with any member, and various adverse effects due to sliding can be prevented.

[0009]

【Example】

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of the present invention, 10 is a lens block in which a lens group 11 for photographing is inserted, the lens block 10 is formed in a cylindrical shape, and a male helicoid is formed on the outer periphery thereof. 10a is formed. Reference numeral 12 denotes a support member provided at a fixed position with respect to the camera body, and the support member 12 has a cylindrical portion 12a formed around the optical axis.
A female helicoid 12b screwed with the male helicoid 10a is formed on the inner circumference of the.

A drive ring 13 is disposed on the outer periphery of the cylindrical portion 12a of the support member 12 so as to be rotatable around the optical axis of the lens group 11, and a flange 13a formed on the outer periphery of the drive ring 13 is pressed down. With the tongue 12c for
It is attached to the support member 12 to the extent that it does not hinder the pivoting movement.

On the other hand, a flange 10b is also formed near the tip of the lens block 10, and the connecting pin 13b erected from the front surface of the drive ring 13 toward the subject is shown in FIG.
As shown in FIG. 3, the driving ring 13 is clamped by a bifurcated clamping piece 10c formed so as to project from a part of the flange 10b.
When the lens block 10 is rotated about the optical axis, the lens block 10 is rotated about the optical axis by the same angle as the drive ring 13 with the holding piece 10c holding the connecting pin 13b. The drive force for turning the drive ring 13 may be, for example, the rotation of a motor or the rotation of a manually operated focus adjustment ring.

Further, a coil spring 14 is provided on the outer periphery of the cylindrical portion 12a of the support member 12, and one end of the coil spring 14 is supported by the front side of the drive ring 13,
Flange 1 having the other end formed on the lens block 10
It is pressed against the back side (film surface side) of 0b.

With this structure, when the drive ring 13 is rotated around the optical axis by a motor or a manual operation, the lens block 10 and the holding piece 10c are connected to the connecting pin 1.
The lens block 10 is moved in the optical axis direction by turning the optical axis center by the same angle as the drive ring 13 while sandwiching 3b and screwing the male helicoid 10a and the female helicoid 12b together. At this time, the lens block 10 is driven by the drive ring 1 supported by the support member 12.
3 is used as a reference, the coil spring 14 rattles in the direction of the object, but since the drive ring 13 and the lens block 10 always rotate at the same angle, the coil spring 14 and the flange 10b are also separated from each other. No sliding motion is generated between the drive rings 13, and problems such as wear of the spring and increase of load due to sliding are suppressed.

Next, FIG. 3 shows another embodiment of the present invention. The embodiment of FIG. 1 urges the lens block toward the subject, whereas the embodiment of FIG. 3 urges the lens block toward the film side. Indicates a code obtained by adding 10 to the code in FIG.

That is, a male helicoid 20a is formed on the outer periphery of the lens block 20 into which a lens group 21 for photographing is inserted, and a supporting member 22 provided at a fixed position with respect to the camera body. Cylindrical part 2 centered on the optical axis
2a is formed, and a female helicoid 22b screwed with the male helicoid 20a is formed on the inner circumference of the cylindrical portion 22a. In this embodiment, the support member 22 itself is, for example, the front frame of the camera body. Further, the flange 23a formed on the outer periphery of the drive ring 23 arranged on the outer periphery of the cylindrical portion 22a of the support member 22 is attached to the support member 22 by the pressing tongue piece 22c as long as it does not hinder the turning motion. ing.

Further, in the embodiment of FIG. 3, the lens block 2
A flange 20b is formed near the rear end of 0, and a connecting pin 23b that is erected from the back surface of the drive ring 23 toward the film side is held by a bifurcated holding piece 20c. The drive ring 23 is centered on the optical axis. When the lens block 20 is rotated, the lens block 20 is rotated about the optical axis by the same angle as the drive ring 23 with the holding piece 20c holding the connecting pin 23b. A coil spring 24 disposed on the outer periphery of the cylindrical portion 22a of the support member 22 has one end supported by the back side (film surface side) of the drive ring 23 and the other end formed on the lens block 20. It is pressed against the front surface (subject surface side) of 20b.

With such a structure, when the drive ring 23 is rotated around the optical axis by a motor or a manual operation, the lens block 20 and the pinching piece 20c are connected to the connecting pin 2.
The lens block 20 moves in the optical axis direction by turning the same angle as the drive ring 23 around the optical axis while sandwiching 3b and screwing the male helicoid 20a and the female helicoid 22b together. At this time, the lens block 20 is rattled in the film direction by the coil spring 24 with the drive ring 23 supported by the support member 22 as a reference, but the drive ring 23 and the lens block 20 are always at the same angle. Since it is turning, no sliding motion is generated between the coil spring 24 and the flange 20b or between the coil spring 24 and the drive ring 23, and problems such as wear of the spring and increase of load due to sliding are suppressed. Will be done.

In the above description, a coil spring centered on the optical axis is used as an example of the biasing means in order to stabilize the amount of force during the stroke of the lens block in the optical axis direction. It goes without saying that the means for energizing is not limited to the above. Also, the relationship between male and female helicoids is not limited to the above-mentioned embodiment, and it goes without saying that the relationship may be opposite to that of the embodiment.

[0020]

As described above, according to the present invention, since the backlash of the lens block is made with reference to the member that always turns at the same angle as the lens block, the gap between the lens block and the spring for backlash is set. No sliding motion is generated between the spring for backlash and the member serving as a reference for backlash, and problems such as wear of the spring and increase in motor load due to sliding can be solved.

[Brief description of drawings]

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

FIG. 2 is a partial plan view showing a relationship between a connecting pin and a sandwiching piece in the mechanism shown in FIG.

FIG. 3 is a sectional view of a lens driving mechanism according to another embodiment of the present invention.

FIG. 4 is a principle diagram of a conventional lens drive mechanism of a cam drive system.

FIG. 5 is a sectional view of a conventional lens driving mechanism of a helicoid driving system.

[Explanation of symbols]

 10 and 11 lens block 10a and 20a male helicoid 11 and 21 lens group 12b and 22b female helicoid 12 and 22 support member 13 23 drive ring 14 and 24 coil spring

Claims (2)

[Claims] 1. A lens driving mechanism comprising at least one helicoid formed at a fixed position with respect to a camera body, and a lens block formed with another helicoid screwed to the one helicoid. A drive ring for turning the lens block by turning at the same turning angle as the lens block, and a biasing means for applying a biasing force in the optical axis direction to the lens block on the basis of the drive ring are provided. Characteristic lens drive mechanism. 2. The lens drive mechanism according to claim 1, wherein a coil spring is provided around the one helicoid as the biasing means, and a force generated at one end of the coil spring is received by the drive ring, A lens driving mechanism, wherein the lens block receives a force generated at the other end of the spring.