JPH1172693A - Lens driving device for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use parts nearly the same size as the parts of the conventional camera and to obtain large driving force for stable actuation by controlling energizing a coil and positioning a lens barrel at a 1st position or a 2nd position. SOLUTION: The male screw part 1d of the lens barrel 1 is screwed and fit in the screw hole 2a of a movable iron piece 2 so as to perform focusing, and the lens barrel 1 can move along an optical axis direction together with the iron piece 2. The iron piece 2 is energized toward the rear part of the camera along an optical axis by springs 3 respectively provided symmetrically with the optical axis as center, and abuts on the plural stoppers 4a and 4b of a lens barrel bottom board 4 so as to keep the optical axis of the lens barrel 1 (1st position). On a yoke 5 round which the coil 6 is wound, both sides of the iron piece 2 are attracted to respective magnetic pole parts against the spring force of the spring 3 by energizing the coil 6 (2nd position). Therefore, photographing in focus is realized by selecting either position in accordance with a subject distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera lens driving device.

[0002]

2. Description of the Related Art A camera of a new system (commonly known as APS) has been reduced in size by about 70% in size, compared with a camera which is conventionally called a 135 format.

For this reason, it is desired that equivalent functions can be obtained with a volume of about 35%. For example, a drive device for auto-focusing (hereinafter abbreviated as AF) of a camera is being studied.

For example, Japanese Utility Model Publication No. Sho 62-32269 has been proposed as an AF driving device using an electromagnetic force as a driving source. In the control by electric conduction, time control is easy and the number of control points due to time is increased. It is used as a feature.

Japanese Patent Application Laid-Open No. 62-254652 discloses a method of driving a photographic lens by using an electromagnetic force. The moving magnet type or the moving coil type has a characteristic that the driving force does not change much with the movement, and this is used.

[0006]

SUMMARY OF THE INVENTION However, APS
Although the system has the features that the lens becomes lighter and the AF stroke becomes shorter, simply reducing the size of the same various parts and members of the camera used in the 135 format reduces the accuracy and strength of the parts. It is conceivable that the operation is unstable due to deterioration and small output, and that the cost is increased due to further refinement.

An object of the invention according to the present application is to provide a highly accurate A
Large drive that uses the same size as the conventional camera parts and does not make the mechanism small (and therefore expensive) for the small lens drive for the F mechanism. It is an object of the present invention to provide a camera lens driving device capable of obtaining a force.

[0008]

A first configuration for realizing the object of the invention according to the present application is a lens driving device for a camera in which an imaging drive lens barrel is moved along an optical axis direction by an electromagnetic driving mechanism. The electromagnetic drive mechanism includes a movable body that can move along the optical axis direction that holds the lens barrel, an urging unit that urges the movable body to a first position and holds the movable body, and energization of a coil. A yoke for holding the movable body at the second position by magnetic force against the urging force of the urging means; and controlling the energization of the coil to move the lens barrel to the first position or the second position. And control means for positioning the position.

This utilizes the advantages and disadvantages that the electromagnetic driving force of the MI system is strong, but the stroke capable of producing a strong force is short.

According to a second configuration for realizing the object of the invention according to the present application, in the first configuration described above, a stopper provided on the yoke is at the second position.

According to a third configuration for realizing the object of the invention according to the present application, in the above-mentioned first configuration, the biasing means comprises a plurality of springs arranged symmetrically with respect to the optical axis.

A fourth configuration for realizing the object of the invention according to the present application is such that, in the first configuration described above, the biasing means is configured by a magnetic circuit including a permanent magnet and a movable iron piece. .

According to a fifth configuration for realizing the object of the invention according to the present application, in the first, second or third configuration described above, the movable body is formed by a flat iron piece parallel to the yoke. It was done.

According to a sixth configuration for realizing the object of the invention according to the present application, in the first, second, third, fourth or fifth configuration described above, the movable body is provided with the optical barrel. It is adapted to be screwed so that the position in the direction can be adjusted.

A seventh configuration for realizing the object of the invention according to the present application is such that, in the sixth configuration described above, a screw portion between the movable body and the lens barrel is a multi-thread screw. .

An eighth configuration for realizing the object of the invention according to the present application is the first, second, third, fourth, fifth, and sixth configurations described above.
Alternatively, in the seventh configuration, the lens barrel is fixed to the movable body with an adhesive.

A ninth configuration for realizing the object of the invention according to the present application is the first, second, third, fourth, fifth and sixth configurations described above.
In the seventh embodiment, the lens barrel has a focal length of 26.
It has a new system lens shorter than mm.

A tenth embodiment which achieves the object of the invention according to the present application is:
Is the first, second, third, fourth, fifth, sixth, seventh, eighth or ninth embodiment, wherein the lens barrel is FNo. It is assumed that the new system lens is darker than 4.5.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIGS. 1, 2 and 3 show a first embodiment of the present invention.
An embodiment will be described.

1 and 2 are a sectional view and an external perspective view of a lens driving device provided on a camera body (not shown).

Reference numeral 1 denotes a lens barrel holding the lenses 1a, 1b, 1c, and a male screw portion 1d is provided on an outer peripheral portion.
The lens constituted by the plurality of lenses is for a new system having a focal length shorter than 26 mm.
No. An APS lens darker than 4.5 is used.

Reference numeral 4 denotes a lens barrel base plate which supports the lens barrel 1 inserted into the guide hole 4d so as to be movable in the optical axis direction, and also has a movable iron piece 2 of an electromagnetic driving device for driving a lens, which will be described later. Stoppers 4a, 4b, 4 for regulating the position in
c (not shown) is formed around the lens barrel 1 on the front end surface. Further, the male screw portion 1d of the lens barrel 1 is screwed into the screw hole 2a of the movable iron piece 2 to enable focus adjustment, and the lens barrel 1 can be moved along the optical axis along with the movable iron piece 2. ing. The male screw portion 1d of the lens barrel 1 and the screw of the screw hole 2a of the movable iron piece 2 are formed as multi-threaded screws, so that the focus adjustment is performed smoothly and is held without play. After the adjustment, the lens barrel 1 is fixed to the movable iron piece 2 with an adhesive to prevent the lens barrel 1 from moving.

The movable iron piece 2 is urged toward the rear of the camera along the optical axis by springs 3 provided symmetrically with respect to the optical axis, and a plurality of stoppers 4 of the barrel base plate 4.
a, 4b, 4c, etc., so that the optical axis of the lens barrel 1 is maintained.

Reference numeral 5 denotes a yoke. Magnetic pole portions extend from both sides of a center portion around which the coil 6 is wound to both sides of the movable iron piece 2. Is attracted against the spring force of the spring 3, and at this time, the lens barrel 1 moves together with the movable iron piece 2 by a predetermined stroke in the optical axis direction.

Accordingly, the first position where the movable iron piece 2 is fixed by the spring force of the spring 3 to a receiving surface on the not-shown barrel base plate 4 which is parallel to the plurality of stoppers 4a, 4b, 4c of the barrel base plate 4. And a second lens position in which the movable iron piece 2 is attracted and held by the magnetic pole portion of the yoke 5, the focus is switched at two positions. If one of the positions is selected according to the subject distance, Thus, in-focus shooting can be performed.

When the movable iron piece 2 is completely attracted to the yoke 5 so that the yoke 5 is parallel to the movable iron piece 2, the optical axis of the lens barrel is maintained in the same manner as when the movable iron piece 2 is pulled by the spring 3. Has become. Reference numeral 7 denotes a shutter, which is attached to the lens barrel base plate 4.

FIG. 3 is a circuit block diagram of an AF device that drives the above-described lens driving device according to the subject distance.

Reference numeral 11 denotes a push-button release switch. When a first stroke switch SW1 of the switch is turned on, a CPU 12 for controlling the entire camera is started, and a distance measuring device 13 starts operating. This distance measuring device 13 is, for example, i
If the subject distance is determined to be a long distance based on the result of distance measurement by the distance measurement device 13, the coil 6 of the electromagnetic drive device is not energized by using a known active system including a RED, a PSD, and a lens. I have. Therefore, the lens barrel 1 is held at a position where the movable iron piece 2 is held in contact with the stopper of the lens barrel base plate 4 by the spring force of the spring 3. In this case, if the configuration of the lens group of the lens barrel 1 is set, for example, at an infinite end, it is possible to perform in-focus shooting.

When it is determined that the subject distance is short based on the distance measurement result of the distance measuring device 13, the coil 6 is energized. Therefore, the movable iron piece 2 moves to a position where it comes into contact with the magnetic pole portion of the yoke 5, and the lens barrel 1 is extended to a position away from the film. In this case, if the configuration of the lens group of the lens barrel 1 is set at the closest end, it is possible to perform in-focus shooting.

After the release switch second stroke switch SW2 is turned on by the further depression of the release button (when the coil 6 operates), the shutter drive circuit 1
4 to perform exposure.

When the distance is short, the coil 6 and the shutter drive circuit 14 are energized simultaneously.

After the exposure, the film is fed to complete a series of movements. If you stay released at that time, repeat the same thing once more. Reference numeral 15 denotes a film feeding circuit.

In this embodiment, a light lens (about 1 g) is used as the lens, and a short stroke (0. 1 g) is used.
(About 3 mm) and an AF mechanism incorporating a lens of about 25 mm of the new system.

Although a spring is used as means for urging the movable iron piece 2 toward the film, it may be constituted by a magnetic circuit composed of a permanent magnet and a movable iron piece.

As described above, in this embodiment, the size of the lens driving device is reduced not by downsizing the components but by simplifying the structure.

That is, the lens barrel becomes lighter, and since the mass is proportional to the volume, about 1/3
become.

Since the focusing stroke becomes smaller, it is also about 1/2, because it is proportional to the square of the length.

Further, a slightly darker lens is employed, and the depth of the lens is utilized.

In order to take advantage of the above features, a method of attaching an iron piece to the lens barrel and directly driving it with an electromagnet is used. It is an electromagnetic drive system that uses lightness, and takes advantage of the movable iron piece system that can take out a large output if the drive stroke is short.

[0040]

According to the present invention, it is possible to efficiently and compactly configure a lens driving device for a camera by directly driving a lens by an electromagnetic driving mechanism of an electromagnet type.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a perspective view of FIG. 1;

FIG. 3 is a circuit block diagram of a camera having the driving device of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Barrel 2 ... Movable iron piece 3 ... Spring 4 ... Barrel base plate 5 ... Yoke 6 ... Coil 7 ... Shutter

Claims (10)

[Claims] 1. A lens driving device for a camera that moves a taking lens barrel along an optical axis by an electromagnetic drive mechanism, wherein the electromagnetic drive mechanism is movable along an optical axis that holds the lens barrel. A movable body, biasing means for biasing the movable body to a first position and holding the movable body, and energizing a coil to move the movable body to a second position against a biasing force of the biasing means. And a control means for controlling the energization of the coil to position the lens barrel at the first position or the second position. 2. The camera lens driving device according to claim 1, wherein a stopper provided on the yoke is at the second position. 3. A lens driving device according to claim 1, wherein said biasing means comprises a plurality of springs arranged symmetrically with respect to an optical axis. 4. A lens driving device for a camera according to claim 1, wherein said urging means comprises a magnetic circuit including a permanent magnet and a movable iron piece. 5. The lens driving device for a camera according to claim 1, wherein the movable body is formed of a flat iron piece parallel to the yoke. 6. The camera according to claim 1, wherein the lens barrel is screwed to the movable body so that a position in an optical axis direction can be adjusted. Lens driving device. 7. The camera lens driving device according to claim 6, wherein a screw portion of the movable body and the lens barrel is a multi-thread screw. 8. The method of claim 1, 2, 3, 4, 5, 6, or 7.
, Wherein the lens barrel is fixed to the movable body with an adhesive. 9. The camera according to claim 1, wherein the lens barrel includes a new system lens having a focal length shorter than 26 mm. Lens driving device. 10. The method of claim 1, 2, 3, 4, 5, 6, 7,
8 or 9, the lens barrel is FNo. 4.5
A lens driving device for a camera, which is a lens for a darker new system.