JPH10254019A - Image blurring correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct shake by effectively canceling or reducing force generated when a correction lens is driven. SOLUTION: A movable frame 31 holding a third group lens being the shake correction lens is held so as to be freely moved within a surface set in a direction being a right angle with an optical axis. Then, a coil spring 33 is held between a fixed frame 30 and the frame 31 so as to be slightly compressed. Besides, the spring 33 is stuck and fixed to the frame 30. Then, the bent part 33a thereof is integrated so as to be engaged with the groove of the frame 31. Since the rotation of the frame 31 around the optical axis is suppressed by the holding force of the spring 33 when the frame 31 is driven, load caused by friction is not generated in comparison with a case that a member guiding by sliding is used. Thus, such failure that the frame 31 is caught when it is started to be moved in the case that it is slightly driven is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image blur correction apparatus for optically correcting camera shake such as camera shake by driving a part of a photographing optical system.

[0002]

2. Description of the Related Art Conventionally, in order to prevent image blur due to camera shake or the like, which is likely to occur during hand-held photographing or the like, a camera shake state is detected by a camera shake detecting means, and a photographic lens system or a part thereof is detected in accordance with the detection result. 2. Description of the Related Art A blur correction device having a configuration in which an optical system is used as a correction lens and the optical system is moved in a direction perpendicular to the optical axis is conventionally known.

In a camera having such a blur correction function, a correction lens constituting at least a part of a photographing lens system is movably supported, and the correction lens is mounted on a plane orthogonal to the optical axis of the main optical system. By moving in the direction in which the blur is absorbed, the shift of the imaging position due to the blur is corrected, and the image blur is intended to be eliminated.

In such a blur correction device, a drive mechanism for moving the correction lens uses a motor as a drive source to transmit a driving force by a gear, a lever, a screw, or the like, and a spring biased from one side. An electromagnetic actuator is configured by a method of pressing and moving a frame, or a coil and a magnet, and one of them is held on a fixed side and the other is held on a correction lens side, and the lens frame is directly moved.

[0005] At this time, if the lens frame rotates around the optical axis, the target drive amount and the actual movement amount deviate, and accurate position detection of the lens frame becomes impossible.
Since accurate blur correction becomes difficult, it is necessary to intervene a guide member that allows the lens frame to move in parallel without rotating. Also, when the guide member is slid, the frictional resistance of the guide member makes it impossible to drive the motor smoothly, especially at the time of correcting the minute amplitude. Therefore, two tension coil springs are attached to the outer periphery of the lens frame at opposing positions with the optical axis interposed therebetween. The rotation of the lens frame is prevented by a radial pulling force.

For example, Japanese Unexamined Patent Publication No. Hei 3-186824 discloses that the thrust generating axis of the driving means coincides with the optical axis of the correction lens, the rotational moment about the optical axis of the correction lens is reduced, and the driving can be performed more smoothly. The configuration is described.

In the structure described in Japanese Patent Application Laid-Open No. 7-28114, the driving force is reduced so as to reduce the rotational moment around the optical axis caused by the friction generated between the driving force transmitting means and the engaging portion of the lens frame. The operation position of the force transmitting means on the lens frame is made closer to the friction generating axis and shifted from the center of the optical axis so that the drive control of the lens frame in a required state can be performed appropriately and reliably.

[0008]

However, in the above-described conventional example, the two tension coil springs are mounted at opposing positions on both sides of the optical axis on the outer periphery of the lens frame as described above. However, there is a problem that large power consumption is required to obtain a target performance. In addition, since a large space is required in the radial direction, there is a problem that downsizing of the device becomes difficult.

Further, in the conventional example in which the thrust generating axis of the driving means and the optical axis of the correction lens coincide with each other, it is assumed that the weight of the correction lens occupies most of the weight of the entire movable part. For example, when the size of an optical system is reduced as in a video lens or a digital still camera, the weight of a lens frame and the like other than the correction lens cannot be ignored.

In particular, when a moving coil type or moving magnet type electromagnetic actuator is used, it is necessary to hold a coil or a magnet, which is a part of the driving means, on a movable portion, and the proportion of the weight thereof is large. Become. Therefore, simply aligning the thrust generating axis of the driving means with the optical axis of the correction lens generates a rotational moment about the optical axis due to weight imbalance, deteriorating the driving characteristics, and further, the position of the correction lens. There is a problem that an error occurs in the detection.

Further, in the prior art in which the rotational moment due to friction is offset, the driving force is transmitted to the driving force transmitting means, and the lens frame is driven via the moving amount generating means. During this period, the guide is used for driving in one direction and driving in the other direction at the same time, so it is necessary to urge the spring from one side. For this reason, the influence of friction is large, and there is an effect as described in the conventional example. However, in a structure in which the lens frame is directly driven as in the moving coil system, the driving amount transmitting means and the moving amount generating means are not provided. Since no member is required and the influence of friction can be reduced, there is a problem that the effect of weight balance is increased by that much.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to effectively cancel or reduce a force generated when a correction lens is driven by a simple and inexpensive structure, to accurately drive the correction lens, and to effectively drive the correction lens. An object of the present invention is to provide a shake correction device capable of performing shake correction.

[0013]

In order to achieve the above object, an image blur correction apparatus according to the present invention comprises: a lens frame movable in a plane substantially perpendicular to an optical axis; A correction lens for holding the lens frame and suppressing blur caused by camera shake and the like, and a fixed frame having a guide portion for moving the lens frame in a plane substantially orthogonal to the optical axis, One end of a coil spring, which is located between the lens frame and the fixed frame and has an inner diameter larger than the effective light beam diameter passing through the correction lens, is held by the lens frame, and the other end is held by the fixed frame. I do.

Further, the image blur correction apparatus according to the present invention is characterized in that a part of the main optical system is movable in a plane substantially orthogonal to the optical axis, and the lens frame is held by the lens frame and shakes due to camera shake or the like. Correction lens for suppressing the
And a second driving force generating means for driving the correction lens in a second direction different from the first direction, the first driving force generating means for driving the correcting lens in a second direction different from the first direction. At least one of the thrust axis centers of the first and second driving force generating means is shifted from the optical axis so as to coincide with the center of gravity of the entire movable part including the lens frame and the correction lens. I do.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 is a sectional view of a zoom lens for a video camera embodying the present invention, and FIG. 2 is an exploded perspective view of the zoom lens barrel of FIG. In FIG. 1, on the optical axis, a first lens unit L1 from the object side, a second lens unit L2 for performing zooming, and a third lens unit serving as a correction lens driven in a direction perpendicular to the optical axis for blur correction. A lens L3, a fourth lens unit L4 for performing focus adjustment, and a low-pass filter F are arranged, and a CC (not shown) is provided behind the low-pass filter F.
A D sensor is arranged.

The first lens unit L1 is held by the front lens barrel 1,
The second lens unit L2 is held by the second lens barrel 2, and the second lens barrel 2 is moved forward and backward by two guide bars 4a, 4b held by the front lens barrel 1 and the rear lens barrel 3. It is movable in the optical axis direction. The third lens unit L3 is held by the correction unit 5, sandwiched between the front lens barrel 1 and the rear lens barrel 3, and fixed by screws. The fourth lens unit L4 is a fourth lens barrel 6
And the guide bars 4a, 4
The low-pass filter F is held by the rear lens barrel 3 so as to be movable in the optical axis direction by b. A stop S is arranged between the second lens unit L2 and the third lens unit L3. The stop S is driven by an electromagnetic stop unit 7, and the electromagnetic stop unit 7 is a front mirror. It is held between the cylinder 1 and the shake correction unit 5.

A drive unit and a screw unit are integrally mounted on a U-shaped sheet metal of the zoom motor 11 composed of a stepping motor, and are fixed to the front lens barrel 1 with screws. On the other hand, a rack 12 is attached to the second lens barrel 2, and the rack 12 is driven in the optical axis direction by meshing with a screw portion of the zoom motor 11. At this time, the rack 12 is urged by a spring 13 in the meshing direction and the optical axis direction, and when meshed, the thrust is removed.

The focus motor 14 is a zoom motor 11
And is fixed to the rear barrel 3 with screws. The fourth group lens barrel 6 has the same rack 1 as the second group lens barrel 2.
5 and a spring 16 are attached, and the rack 15 meshes with a screw portion of the focus motor 14 so that the third group lens
L4 is driven in the optical axis direction.

An interrupter 21 is fixed to the front lens barrel 1 with screws in a state where terminals are soldered to a substrate 22, and a portion between the light projecting portion and the light receiving portion is integrated with the second lens barrel 2. The reference position of the second lens barrel 2 is detected by passing through the slit portion 2a provided in a specific manner, and the lens is driven to each zoom position by the number of pulses input to the zoom motor 11. Similarly, for the focus adjustment, the interrupter 2 in which the slit portion 6a provided in the fourth lens barrel 6 is attached to the rear lens barrel 3 is also used.
3. Detected as a reference position by the substrate 24 and driven stepwise.

FIG. 3 is an exploded perspective view of the shake correction unit 5, and a fixed frame 30 serving as a main body of the correction unit 5 is sandwiched between the front lens barrel 1 and the rear lens barrel 3. The movable frame 31 holds the third group lens L3, which is a blur correction lens, and the pins 32 attached at three locations on the outer periphery engage with the long holes 30a provided in the fixed frame 30 in the circumferential direction, so that the optical axis It is movably held in a plane perpendicular to the direction. A coil spring 33 is held between the fixed frame 30 and the movable frame 31 so as to be slightly compressed. At this time, the coil spring 33 is first adhered and fixed to the fixed frame 30 so that the bent portion 33a has a predetermined phase. Then, the fixed frame 30 and the movable frame 31 are phase-matched by incorporating the bent portion 33a into the groove 31a of the movable frame 31 shown in FIG.

Due to the holding force of the coil spring 33, rotation around the optical axis when driving the movable frame 31 is suppressed.
That is, the rotation cannot be completely stopped because the rotation is prevented by the torsion torque of the coil spring 33. However, compared to the case of using a member that is guided by sliding, a load due to friction does not occur, and a small amount of driving is performed. There is no inconvenience such as being stuck at the beginning of the movement.

The torsion torque of the coil spring 33 is
Even if a rotational moment is applied to the movable frame 31, the movable frame 31 is set to return to a rotational angle that satisfies the target performance against the friction between the pin 32 and the elongated hole 30a. Absent. The coils 34a and 34b are fixed to the movable frame 31 for driving in the horizontal direction, that is, the X direction, and the vertical direction, that is, the Y direction.

In the holes 30c, 30d of the fixed frame 30, the magnets 36a, 3 adsorbed by the lower yokes 35a, 35b are inserted.
6b is inserted and fixed from the back side. The upper yoke 37 is fixed with screws 39 together with the sensor holder 38 from the front to form a magnetic circuit for driving in the X and Y directions. That is, a magnetic circuit is constituted by the magnet 36a, the lower yoke 35a, and the upper yoke 37 for driving in the X direction, and the coil 34a is inserted therein,
For driving in the Y direction, the magnet 36b, the lower yoke 3
5b and the upper yoke 37 constitute a magnetic circuit, into which the coil 34b is inserted, thereby constituting a moving coil type electromagnetic actuator.

Into the sensor holder 38, infrared light emitting diodes 40a and 40b and position detecting light receiving elements 41a and 41b are inserted and fixed from the X direction and the Y direction, respectively. Then, the respective infrared light emitting diodes 40a, 4a
0b, the movable frame 3 between the position detecting light-receiving elements 41a and 41b.
1 and elongated slits 31b, 31 provided integrally with each other.
c are provided, and the infrared light emitting diodes 41a, 41
out of the infrared light projected from b, slits 31b, 31
c only the position detecting light receiving elements 41a, 41
b, the light is received, and the positions of the movable frame 31 in the X and Y directions are detected. These infrared light emitting diodes 40a, 40b, position detecting light receiving elements 41a, 41
b and the electric components of the coils 34a and 34b are connected to a flexible printed circuit board 42, which is divided and connected to a control circuit (not shown) provided on the camera body side.

FIG. 4 is a front view of only the drive unit of the shake correction unit 5. Coil 3 which is an X-direction actuator
4a, the magnet 36a, and the center axis of the yoke 35a are A-
Assuming that the center axis of the coil 34b, the magnet 36b, and the lower yoke 35b as the A-line and Y-direction actuators is the BB line, the center axes of the thrusts in the X and Y directions are the A-A line and BB
The lines coincide with the lines, and are shifted from the center of the optical axis of the third lens unit L3, which is a blur correction lens, toward the driving actuators in the other directions. A point G is a third group lens L3 which is a movable portion, a movable frame 31, coils 34a and 34b, and a pin 32.
And the center of gravity of the thrust center line A-A, B-
The line B is set to cross the center of gravity G. This makes it possible to reduce the rotational moment caused by the weight imbalance.

In the moving magnet system as in this embodiment, since the lens frame can be directly driven, a driving force transmitting member is not required, and the portion where friction is generated can be reduced. Further, since the pin 32 and the long hole 30a are also provided at three locations in the circumferential direction at equal intervals, the rotational moment generated by frictional force and viscous resistance at that portion is small. For this reason, the influence of weight imbalance increases as a factor for generating a rotational moment in the third lens unit L3, and the thrust generation center axis of the driving means passes through the center of gravity of the entire movable unit as in the present embodiment, and the lens Since the rotational moment generated in the frame can be satisfactorily suppressed, and it is possible to drive accurately to the target position, an image blur correction device having a high blur correction effect can be realized.

[0027]

As described above, according to the image blur correction apparatus of the present invention, the lens frame moves in a direction substantially perpendicular to the optical axis while the rotation of the lens frame around the optical axis is suppressed by the torsion torque of the coil spring. This makes it possible to prevent the drive characteristics and the position detection accuracy from deteriorating despite the simple structure. In addition, the characteristics can be prevented from deteriorating at the time of minute driving due to sliding, so that effective correction can be performed even for slight camera shake.

Further, according to the image blur correction apparatus of the present invention, the rotational moment around the optical axis caused by the imbalance of the weight of the entire movable part can be reduced, so that the drive characteristics deteriorated. Deterioration in position detection accuracy can be prevented, and good blur correction can be performed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a zoom lens for a video camera according to an embodiment.

FIG. 2 is an exploded perspective view of a zoom lens barrel.

FIG. 3 is an exploded perspective view of the shake correction unit.

FIG. 4 is a front view of a drive unit of the shake correction unit.

[Explanation of symbols]

 L3 Third lens group 5 Image stabilizer unit 30 Fixed frame 31 Movable frame 32 Pin 33 Coil spring 34a, 34b Coil 35a, 35b Lower yoke 36a, 36b Magnet 37 Upper yoke 40a, 40b Infrared light emitting diode 41a, 41b Position detecting light receiving element

Claims (3)

[Claims] A lens that is movable in a plane substantially orthogonal to an optical axis of a part of the main optical system, a correction lens that is held by the lens frame, and that suppresses blur caused by camera shake or the like; A fixed frame having a guide portion for moving the lens frame in a plane substantially orthogonal to the optical axis, wherein the effective frame diameter is located between the lens frame and the fixed frame and passes through the correction lens. An image blur correction device, wherein one end of a coil spring having a large inner diameter is held by the lens frame and the other end is held by the fixed frame. And a correction lens for holding a part of the main optical system in a plane substantially orthogonal to the optical axis and holding the lens frame to suppress blur caused by camera shake and the like. A first driving force generating means for driving the correction lens in a first direction; and a second driving force generating means for driving the correction lens in a second direction different from the first direction. Wherein at least one of the centers of the thrust axes of the first and second driving force generating means is offset from the optical axis so as to coincide with the center of gravity of the entire movable portion including the lens frame and the correction lens. An image blur correction device, characterized in that: 3. The image blur correction device according to claim 2, wherein the first direction and the second direction are orthogonal to each other.