JPH07248522A - Optical device - Google Patents

Abstract

PURPOSE:To make an optical device inexpensive, light in weight and small in size and to perform quiet operation by suspending and supporting the holding frame of an optical element for correcting image blurring to the optical device by magnetic force and moving the holding frame in a direction orthogonally crossing an optical axis by controlling the magnetic force. CONSTITUTION:Magnetic force generating members 204 to 207 such as a permanent magnet or an electromagnet hold the holding member 35 of a 2nd lens group 32 and the holding member 36 of a 4th lens group 34 functioning as the optical element for correcting image blurring on an image formation surface in non-contact with a housing 41 in a direction perpendicular to the optical axis. Magnetic force generating members 201 to 203 move the holding members 35 and 36 in non-contact with the housing 41 in the optical axis direction and the suspension is supported. A control means converts vibration such as camera shake detected by a shake sensor into a displacement value to be corrected and controls the magnitude of a current flowing in the electromagnets 203, 205 and 207 out of the generating members 201 to 207, so that the holding members 35 and 36 are moved in the direction perpendicular to the optical axis direction and image blurring is restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device such as a camera or an observation instrument, and more particularly to an optical device having an image blur correcting optical element for correcting the blur on an image plane.

[0002]

2. Description of the Related Art As a means for suppressing blurring of a photographed image due to vibration such as camera shake, a blur correction mirror for suppressing image blur by moving a part of lenses constituting a photographing lens in a direction perpendicular to an optical axis. The cylinder is known. FIG. 6 is a block diagram of a zoom lens equipped with a conventional shake correction mechanism. In FIG. 6, 1a is a first lens group, 1b is a second lens group, 1c is a third lens group, and 1d is a fourth lens group.
Among them, the second lens group 1b is moved to the fourth
The lens group 1d is movable in a predetermined range along the optical axis for focusing. Further, the blur is corrected by moving the fourth lens group 1d in a direction perpendicular to the optical axis direction by a blur correction mechanism described later. Reference numeral 2 is an optical low-pass filter, and 3 is an image pickup device such as a CCD. Reference numeral 4 denotes a housing that holds the first lens group 1a, the third lens group 1c, the image pickup device 3, and the like. Reference numeral 5 is a lens holding member of the second lens group, and 6 is a guide bar for guiding the movement of the second lens group holding member 5 in the optical axis direction. A feed screw 7 is parallel to the optical axis and is screwed into a screw hole provided in the second lens group holding member 5 to move the holding member 5 in the optical axis direction. The feed screw 7 also meshes with a biasing member 9 which is biased by a biasing spring 8, and the member 9 removes backlash from the screwed portion. The second lens group holding member 5 moves in the optical axis direction while being supported by the guide bar 6 and the feed screw 7. 1
0 is a step motor, and the motor 10 is a gear group 1
The feed screw 7 is rotationally driven via 1 to drive the second lens group holding member 5. Reference numeral 12 is a lens frame of the fourth lens group 1d (that is, an image blur correction lens), and 13 is a holding frame of the lens frame 12. The lens frame 12 is carried on a holding frame 13, and is movable in a direction (radial direction) perpendicular to the optical axis while slidingly contacting the front flange 13a and the rear flange 13b of the holding frame 13. Movement is restricted in the axial direction. Reference numeral 14 is a biasing spring. Reference numeral 15 is a pressing pin, 16 is a drive motor of the shake correction mechanism, and 17 is a drive lever. The urging spring 14 urges the lens frame 12 upward in the drawing, and the tip of the pressing pin 15 is driven by the drive lever 17.
The urging spring 14 pushes the lens frame 12 in a direction opposite to the urging direction, and the lens frame 12 is positioned in the direction perpendicular to the optical axis direction.

Focusing operation is performed by moving the holding frame 13 in the optical axis direction by screwing the feed screw 19 directly connected to the focusing step motor 18 and the screw hole of the holding frame 13. A diaphragm member 20 changes the aperture diameter of the diaphragm by a power source 21 such as a motor.

FIG. 7 is a block diagram of the above-mentioned shake correction mechanism as viewed from the objective side. In FIG. 7, the same components as those in FIG. 6 are denoted by the same reference numerals, x is added to the components of the correction mechanism in the x direction, and y is added to the components of the correction mechanism in the y direction. To represent. Reference numeral 401 is a shake sensor such as an angular velocity meter, and 402 is a position sensor that detects the position of the fourth lens group 1d in the x and y directions. Reference numeral 403 is a control circuit of the shake correction mechanism. The blur sensor 401 is fixed to the lens barrel, that is, the housing 4 described above, detects vibration such as camera shake as an angular velocity, and the detected signal is converted into a displacement value to be corrected by the control circuit 403.
The drive motor 16 is driven by the output signal of this displacement value, and the drive motor 16 is driven through the drive lever 17 and the pressing pin 15
The lens group 1d is moved to suppress image blur, and the image is stabilized on the image pickup surface.

[0005]

In the above-mentioned conventional example, all of the image blur correction mechanism is mounted on the movable lens frame which must be moved in the optical axis direction during zooming and focusing, so that the movable lens is used. Since the total weight of the frame is very large, and therefore the inertial mass of the movable lens frame is very large, it is difficult to perform zooming and focusing quickly. In order to perform zooming and focusing quickly, A large output motor is required, resulting in not only an increase in size of the optical device and an increase in cost, but also a drawback that power consumption, friction loss, and generated noise increase.

Therefore, it is an object of the present invention to provide an improved optical device which does not have such drawbacks.

[0007]

In the above-mentioned conventional optical device, the lens frame is supported by the optical device by mechanical contact, and the moving mechanism of the lens frame is a mechanical device such as a feed screw yalicoid as described above. Since the structure has friction, a large starting force is required to overcome the static friction force when the lens frame is activated, and a driving force sufficient to overcome the dynamic friction resistance is required during driving. Moreover, since a structure having high mechanical rigidity is required to support the weight of the lens frame, the weight of the optical device must be heavy in order to increase the rigidity of the optical device.

In the present invention, at least the holding frame of the image blur correction optical element is supported by the optical device in a non-contact manner and moved in a non-contact manner as a means for solving the problems inherent in the above-mentioned prior art. I decided to adopt a configuration that allows it. Specifically, support means for floatingly supporting the movable lens holding frame including the holding frame of the image blur correction optical element by magnetic force is provided, and the magnetic force of the supporting means is changed to move the lens holding frame to the optical device. It was designed to be moved without contact. The technical idea of floatingly supporting the movable lens frame by magnetic force and moving it in the optical axis direction by magnetic force is well known, and is disclosed in, for example, JP-A-59-198.
No. 409 publication.

The present invention solves the problems of the conventional optical device with the image blur correction function by applying this known technique.

[0010]

1 is a sectional view of a first embodiment of an optical device according to the present invention.

In FIG. 1, 31 is the first lens group, and 32 is
Is a second lens group, 33 is a third lens group, and 34 is a fourth lens group. Among them, the second lens group 32 is movable for zooming, and the fourth lens group 34 is movable in a predetermined range along the optical axis for focus adjustment. The second lens group 32 and the fourth lens group 34 also serve as image blur correction optical elements, and the image blur on the image plane is corrected by moving the lens group in the direction perpendicular to the optical axis direction. .
Reference numeral 37 is an optical low-pass filter, and 38 is an image pickup device such as a CCD. 41 is a first lens group 31 and a third lens group 3
3, a housing that holds the image sensor 38 and the like. Reference numeral 35 is a second lens group holding member, 39 is an aperture member, and 40 is a drive source for driving the aperture member 39.

Reference numerals 204 to 207 denote second lens group holding members 3
A magnetic force generating member such as a permanent magnet or an electromagnet for holding the fifth and fourth lens group holding members 36 in a direction perpendicular to the optical axis in a non-contact manner with respect to the housing 41.
Reference numeral 203 denotes a magnetic force generating member such as a permanent magnet or an electromagnet for moving the second lens group holding member 35 and the fourth lens group holding member 36 in the optical axis direction in a non-contact manner with respect to the housing 41 and floatingly supporting them. is there. In the present embodiment, the second lens group 3 movable in the optical axis direction for zooming.
2 and a fourth lens group 3 which is movable in the optical axis direction for focusing.
Since the supporting means and the driving means for 4 have the same configuration, the second lens group holding member 35 will be described in the following description.

FIG. 2 is a structural diagram of a magnet which constitutes a supporting means and a driving means for the second lens group holding member 35. In FIG. 2, 201 and 202 are permanent magnets, which are fixed to the housing 41. Reference numeral 203 denotes an electromagnet including a coil and an iron core, which is fixed to the second lens group holding member 35. By using these magnets, the second lens group holding member 35 is moved in the optical axis direction in a non-contact manner by a method described later. Reference numerals 204 and 206 denote permanent magnets, which are fixed to the second lens group holding member 35. Reference numerals 205 and 207 are electromagnets, which are fixed to the housing 41. Using these magnets, the second lens group holding member 35 is held in a non-contact manner in a direction perpendicular to the optical axis by a method described later.

Reference numeral 42 is a control means for changing the magnetic force of the electromagnets 203, 205, 207.
Is for detecting the position of the second lens group holding member 35 (FIG. 7).
And the output of a blur sensor (not shown) (the same as that shown in FIG. 7) are taken in, and the control means 42 controls the energization time and the energization direction of the electromagnet by a predetermined calculation.

The method of moving the second lens group holding member 35 in the optical axis direction is the same as the method described in JP-A-59-198409.

The facing surfaces of the permanent magnet 201 and the permanent magnet 202 have the same polarity (N pole in FIG. 2). When a current is applied to the electromagnet 203 and the polarity becomes as shown in FIG.
The lens group holding member 35 moves in the third lens group direction (right side in FIG. 2), and when a current in the opposite direction is applied to the electromagnet 203, the second lens group holding member 35 moves in the first lens group direction (in FIG. 2). Move to the left side). Therefore, by controlling the current flowing through the electromagnet 203 by the control means 42, the position of the second lens group holding member 35 in the optical axis direction can be controlled.

The supporting means for supporting the second lens group holding member 35 in a direction perpendicular to the optical axis direction without contact is a permanent magnet 204.
And 206 and electromagnets 205 and 207.
The electromagnet 205 is energized so that the facing surfaces of the permanent magnet 204 and the electromagnet 205 have the same polarity. Similarly, the electromagnet 207 is energized so that the facing surfaces of the permanent magnet 206 and the electromagnet 207 have the same polarity. Permanent magnet 20
4 and the electromagnet 205, and the permanent magnet 206 and the electromagnet 207 repel each other due to the magnetic force, and the repulsive force depends on the magnitude of the current flowing through the electromagnets 205 and 207. Therefore, the magnitude of the current flowing through the electromagnets 205 and 207 is By controlling, the second lens group holding member 35 can be held in a non-contact manner at a predetermined position in the direction perpendicular to the optical axis direction. Therefore, the vibration of the camera shake or the like detected by the blur sensor (not shown) is converted into a displacement value to be corrected by the control means 42 and the magnitude of the current flowing through the electromagnets 205 and 207 is controlled to control the second lens group holding member 35. Is moved in a direction perpendicular to the optical axis direction, image blur is suppressed, and the image is stabilized on the imaging surface. As described above, in the present embodiment, the fourth lens group holding member 36 also has the same configuration, so that the fourth lens group 34 can also perform blur correction.

Further, a current is passed through the electromagnet 203, and the first
After the second lens group 32 is moved in the lens group direction (left side in FIG. 2) or the third lens group direction (right side in FIG. 2) and the electromagnet 203 and the permanent magnet 201 or the permanent magnet 202 are attracted, the electromagnet 203, 205, 20
Even when the power supply to 7 is stopped, the iron core of the electromagnet 203 and the permanent magnet 201 or the permanent magnet 202 are attracted to each other.
The second lens group holding member 35 is fixedly supported on the housing 41.

As described above, in the structure of the present embodiment, the lens holding member of the movable lens group is supported in non-contact with the lens barrel, so that a shake correction mirror capable of high-speed autofocusing or zooming operation is provided. A cylinder can be realized.

In the above embodiment, the repulsion by the magnetic force is used for the non-contact support of the second lens group holding member 35 in the direction perpendicular to the optical axis direction, but the direction of the current flowing through the electromagnets 205 and 207 is changed to the permanent magnet 204. , 206 and electromagnet 20
The second lens group holding member 35 may be supported in a non-contact manner in a direction perpendicular to the optical axis direction by utilizing suction by an energizing magnetic force so that the polarities of the surfaces opposed to 5, 207 are different. Further, as shown in FIG. 3, instead of the permanent magnets 204 and 206, the electromagnet 5
The configuration may be such that 01 and 502 are fixed to the outer peripheral surface of the second lens group holding member 35. Furthermore, as shown in FIG.
A configuration may be adopted in which a magnetic force generating member such as a permanent magnet or an electromagnet for controlling the position of the second lens group holding member 35 in the optical axis direction is arranged so that the magnetizing direction is the optical axis direction. In FIG. 4, 601 and 603 are permanent magnets, and 602
And 604 are electromagnets. The electromagnet 602 has a permanent magnet 6
The current is energized so that the direction of the magnetic pole is the same as that of 01. At this time, the permanent magnet 601 and the electromagnet 602 repel each other due to the magnetic force. Similarly, the electromagnet 604 is also energized, and the permanent magnet 603 and the electromagnet 604 repel each other due to the magnetic force. Therefore, by controlling the current flowing through the electromagnets 602 and 604, the second lens group holding member 35 (or the fourth lens group holding member 36) can be supported in a non-contact manner at a predetermined position in the direction perpendicular to the optical axis direction. .

Further, as shown in FIG. 5, for example, a plastic magnet or the like may be used for the permanent magnet to integrally mold the movable lens holding member or the housing. In FIG.
Reference numerals 701 and 702 denote plastic magnet portions that are integrally formed and magnetized with the housing 41, and 703 is a plastic magnet portion that is integrally formed and magnetized with the movable lens holding member (35, 36). With such a configuration, the manufacturing cost can be reduced.

[0022]

As described above, in the optical device of the present invention, the holding means for the image blur correction optical element is floatingly supported by the magnetic force with respect to the optical device, and the control means for fetching the output signal of the blur detection means is used. Since the magnetic force is controlled by the above, the problems relating to the drive of the image blur correction optical means in the conventional optical device with the image blur correction function are solved,
As a result, it is possible to realize an improved optical device that is lighter and smaller than the conventional device, can operate quietly, and is highly economical.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of an optical device according to the present invention.

FIG. 2 is a detailed view of a part shown in FIG.

FIG. 3 is a diagram showing a modified embodiment of the portion shown in FIG.

FIG. 4 is a diagram showing a modified example of the portion shown in FIG.

5 is a diagram showing a modified example of the portion shown in FIG.

FIG. 6 is a schematic cross-sectional view of a known lens barrel having a built-in image blur correction mechanism.

FIG. 7 is a conceptual diagram of the structure shown in FIG. 6 in which only the image blur correction mechanism is extracted and viewed from the front end side of the lens barrel.

[Explanation of symbols]

1a ... 1st lens group 1b ... 2nd lens group 1c ... 3rd lens group 1d ... 4th lens group 2 ... Optical low pass filter 3 ... Imaging element 4 ... Housing 5 ... 2nd lens group holding member 6 ... Guide bar 7 ... Feed screw 8 ... Offset spring 9 ... Offset member 10 ... Step motor 11 ... Gear group 12 ... Lens frame 13 ... Holding frame 14 ... Energizing spring 15 ... Pushing pin 16 ... Shake correction motor 17 ... Drive lever 18 Focusing step motor 19 Feed screw 20 Aperture member 21 Power source 31 First lens group 32 Second lens group 33 Third lens group 34 Fourth lens group 35 Second lens group holding member 36 ... Fourth lens group holding member 37 ... Optical low-pass filter 38 ... Imaging element 39 ... Aperture member 40 ... Power source 41 ... Housing 42 ... Control means 201, 202, 204, 206 ... Permanent Magnet 203,205,207,501,502,602,6
04 ... Electromagnet 701-703 ... Plastic magnet part

Claims (3)

[Claims] 1. An optical device having an image blur correction optical element for correcting image blur on an image forming surface, wherein a holding frame of the image blur correction optical element is floatingly supported on the optical device by magnetic force. And a magnetic force control unit for controlling the magnetic force of the supporting unit to move the holding frame in a direction orthogonal to the optical axis of the optical device. apparatus. 2. The optical device according to claim 1, wherein the supporting means utilizes repulsive force of magnetic force. 3. The optical device according to claim 1, wherein the support means utilizes a magnetic attraction force.