JPH09179010A - Lens driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens driving device which requires a small storage space and has small variation in energizing force and is equipped with an energizing spring capable of minimizing the tilt of a lens unit to an optical axis. SOLUTION: This driving device is equipped with driving mechanisms 12a and 22a which drive the lens unit 20 along the optical axis and the energizing spring 30 which energizes the lens unit 20 along the optical axis. In this case, the energizing spring 30 is constituted by stacking plural leaf springs 31 (32) each having a main body supported by a spring receiver 11a and one nearly arcuate spring part 31b (32b) raised from the main body so as to depress the lens unit 20 along the optical axis.

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 provided with a biasing spring for driving a lens to a desired position with high accuracy.

[0002]

2. Description of the Related Art In photography, it is necessary to accurately drive a focusing lens, which constitutes a taking lens, to an appropriate position in the optical axis direction according to a subject distance or the like in order to surely obtain a focused image. is there. for that purpose,
It is essential to remove the play between the helicoid screws for driving the lens, the play between the cam groove and the cam follower, and the tilting of the lens with respect to the optical axis. Biasing in the optical axis direction has been conventionally performed.

FIG. 4 shows an example of a conventional helicoid type focusing mechanism, 10 is a shutter unit, and 20 is a focusing lens unit screwed to the shutter unit 10. When the lens unit 20 is rotated by the drive source in the shutter unit 10, the lens unit 20 is moved in the optical axis direction by the action of the screw, thereby performing focusing. 40 is both units 10,
It is a compression coil spring for removing play, which is interposed between 20 and biases the lens unit 20 in the optical axis direction (direction A in the drawing) to remove the play between the screws.

FIG. 5 shows an example in which an annular leaf spring 50 is used as a spring for removing backlash, and the leaf spring 50 has a plurality of (two in the figure) substantially arcuate shapes for pressing the lens unit 20. It has an arm 51.

[0005]

In recent years, the number of lenses has increased and the structure has become complicated with the increase in magnification of photographing lenses. Therefore, in consideration of downsizing of the lens barrel, there is no play. It is recommended that the storage space for the urging spring be as small as possible. However, the compression coil spring 40 shown in FIG.
Has a long length when contracted, and is difficult to store in a small storage space. Further, particularly in a lens shutter camera, the lens unit 20 is often driven by the drive mechanism provided in the shutter unit 10 as described above, and the spring force of the backlash removing spring is as small as possible in order to reduce the load on the drive mechanism. It needs to be mitigated. However, in order to reduce the spring force of the compression coil spring, it is necessary to make the wire diameter thin. If the wire diameter is made thin, the ratio of the wire diameter to the spring outer diameter (outer diameter / wire diameter) becomes large, and the manufacturing It will be difficult.

On the other hand, an annular leaf spring 5 as shown in FIG.
0 is advantageous in terms of space as compared with the coil spring because the thickness when contracted is the plate thickness. However, since the leaf spring is made by punching out one plate, the arc-shaped arm 5
The length of 1 is at most the length of the circumference divided by the number of arms 51. That is, if a plurality of arms 51 are provided, each arm 5
There is a problem that the length of 1 must be shortened, fluctuation of the urging force with respect to the bending amount of the arm 51 becomes large, and the stroke of the lens cannot be long. Since the length of the arm 51 can be maximized by using only one arm 51, the fluctuation of the urging force is small, but since the lens unit can be supported only at one place, the tilt of the lens unit with respect to the optical axis occurs. However, the driving accuracy may be reduced.

An object of the present invention is to provide a lens driving device provided with a biasing spring that requires a small accommodation space, has little fluctuation in biasing force, and can minimize tilting of the lens unit with respect to the optical axis. Especially.

[0008]

FIG. 2 shows an embodiment of the present invention.
The present invention relates to the lens unit 2
The present invention is applied to a lens drive device including drive mechanisms 12a and 22a for driving 0 in the optical axis direction and a biasing spring 30 for biasing the lens unit 20 in the optical axis direction.

Then, a main body 31a (32a) supported by the spring receiver 11a and one substantially arc-shaped spring portion 31b (32b) raised from the main body to press the lens unit 20 in the optical axis direction. The bias spring 30 is configured by stacking a plurality of leaf springs 31 (32) having the above-mentioned structure, thereby solving the above problem.

According to the second aspect of the present invention, the biasing spring 30 is used as a spring for eliminating play between the drive mechanisms 12a and 22a and the engaging portion of the lens unit 20.

According to a third aspect of the invention, the lens unit 20 is driven in the optical axis direction while rotating about the optical axis,
Each spring portion 31b when viewed from the lens unit 20 side,
Each leaf spring 3 is arranged so that the extending direction of 32b coincides with the rotating direction of the lens unit 20 driven to the urging spring 30 side.
1, 32 are configured.

In the present invention, the biasing spring 30 has the body 31a.
One substantially arcuate spring part 3 raised from (32a)
Since a plurality of leaf springs 31 (32) having 1b (32b) are superposed, a plurality of spring portions having a long length can be provided.

Incidentally, in the section of means for solving the above-mentioned problems for explaining the constitution of the present invention, the drawings of the embodiments are used for the sake of easy understanding of the present invention. It is not limited to.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. The same parts as those in FIG. 4 are designated by the same reference numerals.

FIG. 1 is an external view of a focusing mechanism (lens driving device) according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view thereof. This focusing mechanism is used for a lens shutter camera, for example, and includes a shutter unit 10, a focusing lens unit 20, and
A bias spring 30 for removing play is provided between the two.

The shutter unit 10 has a housing space for housing the focusing lens unit 20. The accommodation space is composed of a large diameter portion 11 on the front end side and a small diameter portion 12 on the rear end side, and the rear wall surface 11a of the large diameter portion serves as a spring receiver. A lever 11b for rotating the lens unit 20 within a predetermined angle range is provided at the tip of the large diameter portion 11 while the lens unit 2 is provided on the inner peripheral surface of the small diameter portion 12.
A female screw 12a for driving 0 in the optical axis direction is engraved. Although not shown, the shutter unit 10 accommodates a lens shutter and a drive unit for driving the lever 11b. Reference numeral 13 is a flexible printed circuit board for electrically connecting this drive unit to a control circuit on the camera body side.

The focusing lens unit 20 comprises a focusing lens 21 and a holder 22 for holding the lens 21, and a male screw portion 22a projecting from the rear portion of the holder 22 is screwed into a female screw 12a of the shutter unit 3. . The shutter unit 3 is provided on the outer peripheral surface of the holder 22.
A pair of claws 22b that engage with the lever 3a is provided in a protruding manner.

The urging spring 30 is formed by stacking a pair of leaf springs 31, 32 of the same shape shown in FIGS. 3 (a) and 3 (b) on top of each other as shown in FIG. 3 (c). In the figure, one of the leaf springs 32 is provided so that the leaf springs 31 and 32 can be easily distinguished.
Is hatched.

Each of the leaf springs 31 and 32 is formed by punching out one plate, and has an annular body 31a,
32a and one substantially arcuate arm 31b, 32b provided along the inner surface of the main body 31a, 32a.
The arms 31b and 32b are made as long as possible so as to form a substantially circle, and are raised so as to be farther from the main bodies 31a and 32a toward the tips (see FIG. 2). The arms 31b and 32b thus raised enter the center side toward the tips, but in the present embodiment, the inside R of the arms 31b and 32b is larger than the base end side, and The part is suppressed from entering the center side.

Main bodies 31a, 3 of the pair of leaf springs 31, 32
FIG. 3C is a diagram in which the phases 2a are overlapped with each other with a phase difference of 180 degrees. In this state, as shown in FIG. 2, the tip end side of the other arm 32a is located above the base end side of the one arm 31b, and the tip end portion of the one arm 31b is above the base end side of the other arm 32a. Will be located.

During assembly, the main bodies 31a, 32 of the biasing spring 30 are
a is a spring receiver 11 formed in the shutter unit 10.
supported by a. Here, there is no problem as long as the main bodies 31a and 32a are fixed to each other by adhesion or the like. Alternatively, it is necessary to provide notches and engage these with bosses provided on the spring receiver 11a.

The male screw portion 22a of the lens unit 20 is
It penetrates the biasing spring 30 and is screwed into the female screw portion 12 a of the shutter unit 10. When the lever 11a is driven by the drive unit in the shutter unit 10, the holder 22 of the lens unit 20 is rotated via the claw 22b, and the focusing lens 21 moves integrally with the holder 22 in the optical axis direction by the action of the screw. Focusing is performed.
The tip ends of the pair of arms 31b and 32b that form the biasing spring 30 come into contact with the back surface of the holder 22 and the lens unit 20.
To the front of the optical axis (direction A), which causes the lens 21
The play between the screws 12a and 22a is removed regardless of the feeding position. Therefore, the lens unit 20 can be accurately driven to a desired position.

The thickness of the urging spring 30 when contracted is equal to that of the leaf spring 3.
The thickness of the plates forming the parts 1 and 32 is twice as thin as the thickness of the plates, so that the space for accommodating the biasing spring 30 is small. Also arm 31
Since the lengths of b and 32b are long, the fluctuation of the urging force with respect to the bending amount of the arms 31b and 32b can be minimized, and the lens unit 20 can be applied to a long moving amount. Further, since the lens unit can be supported at two places, the tilt of the lens unit 20 with respect to the optical axis is suppressed. In particular, in the present embodiment, the pair of leaf springs 31 and 32 having the same shape are overlapped with the phases shifted by 180 degrees, so that the lens holder 20 is pressed by the arms 31b and 32b at two positions symmetrical with respect to the optical axis. As a result, the lens unit 20 can be surely prevented from falling.

By the way, in the present embodiment, when the lens unit 20 rotates in the clockwise direction in FIG. 2, the lens unit 20 moves toward the shutter unit 10, that is, the biasing spring 3.
It is configured so as to be rolled up to the 0 side. On the other hand, each arm 31 when the biasing spring 30 is viewed from the lens unit 20 side
The extending directions of b and 32b are also the clockwise direction, that is, the direction coinciding with the rotating direction of the lens unit 20 driven to the biasing spring 30 side. Therefore, when the lens unit 20 is retracted to the biasing spring 30 side, the arms 31b,
The tip portion of 32b does not bite into the end surface of the rotating male screw portion 22a, and the movement of the lens unit 20 is not hindered.

In the configuration of the above embodiment, the screw 1
2a and 22a form a drive mechanism, and the arms 31b and 32b form a spring portion.

In the above description, the urging spring 30 is used as a spring for removing the looseness of the threaded portion. However, when the lens is driven by the cam mechanism, the urging spring 30 is used for eliminating the looseness between the cam groove and the cam follower. It may be used as a spring. Also,
Although the focusing mechanism has been described, the present invention can be similarly applied to other lens driving mechanisms including a biasing spring that biases the lens in the optical axis direction, such as an adjusting mechanism that adjusts the position of the lens in the optical axis direction.

[0027]

According to the present invention, a plurality of leaf springs having one substantially arcuate spring portion which is erected from the main body to press the lens unit in the optical axis direction are superposed on each other to form a biasing spring. Since it is configured, the thickness at the time of contraction can be made smaller than that of the coil spring, and the accommodation space can be small. In addition, since the length of the spring part can be increased, the fluctuation of the biasing force with respect to the bending amount is small, the stroke of the lens can be long, and the number of spring parts can be increased, so that the lens unit can be supported at a plurality of positions. It is possible to minimize the inclination of the optical axis with respect to the optical axis. If such a biasing spring is used as a spring for eliminating play between the lens unit and the lens driving mechanism, the lens can be driven to a desired position with high accuracy.

If the leaf springs are configured so that the extending direction of each spring portion when viewed from the lens unit side coincides with the rotation direction of the lens unit driven to the biasing spring side, the tip portion of the spring portion will be Never go into the lens unit.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the outer appearance of a focusing mechanism according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of FIG.

FIG. 3 is a diagram illustrating a configuration of a biasing spring.

FIG. 4 is a perspective view showing a conventional example in which a compression coil spring is used as a biasing spring.

FIG. 5 is a perspective view showing a conventional example using a leaf spring as an urging spring.

[Explanation of symbols]

 10 Shutter unit 11a Spring receiver 12a Female screw 20 Lens unit 21 Focusing lens 22 Holder 22a Male screw part 30 Energizing spring 31,32 Leaf spring 31a, 32a Main body 31b, 32b Arm

Claims (3)

[Claims] 1. A lens drive device comprising a drive mechanism for driving a lens unit in the optical axis direction and a biasing spring for biasing the lens unit in the optical axis direction, wherein the biasing spring is a spring bearing. It is composed of a plurality of leaf springs having a main body to be supported and one substantially arc-shaped spring portion raised from the main body to press the lens unit in the optical axis direction, and each spring portion is different. A lens driving device, wherein each of the main bodies is superposed so as to press the lens unit at a position. 2. The drive mechanism is configured to be engaged with an engaging portion of the lens unit to relatively move the lens unit in an optical axis direction, and the biasing spring includes the drive mechanism and the lens unit. The lens driving device according to claim 1, wherein the lens driving device is a spring for eliminating play between the lens driving device and the engaging portion. 3. The drive mechanism is configured to drive the lens unit in the optical axis direction while rotating the lens unit about the optical axis, and the extending direction of each spring portion when viewed from the lens unit side is 3. The lens driving device according to claim 1, wherein each of the leaf springs is configured so as to match the rotation direction of the lens unit driven to the biasing spring side.