JP3421447B2 - Camera with image blur correction function - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention offsets the movement of a subject image on the finder due to the blur by deflecting the optical axis of the finder optical system when the camera vibrates with respect to the subject due to camera shake or the like. The present invention relates to a camera having an image blur correction function that can be performed.

[0002]

2. Description of the Related Art A conventional image blur correction device integrates an output signal from an angular velocity sensor provided as a blur detection means to calculate a blur amount, and based on the calculation result, it is provided in an optical path of a photographing optical system. By driving the correction optical system thus obtained, the movement of the subject image on the image receiving surface of the camera, for example, the film surface or the light receiving surface of the photoelectric conversion element is compensated.

Generally, a camera having a conventional image blur correction function continues processing such as blur detection for correction and calculation of a driving amount of a correction optical system for blur correction from the time when the power is turned on. However, the correction optical system is actually driven to correct the image blur on the image receiving surface only during the period when the shutter is released and the exposure and the photographing are performed.

[0004]

However, in the conventional camera having the image blur correction function described above, the image blur correction function is not activated while the photographer is observing the subject image through the viewfinder. However, if the camera vibrates due to camera shake or the like, the subject image vibrates, which hinders focusing and composition determination.

On the other hand, if the image blur correction function is always operated after the power is turned on, the image blur is caused even when the photographer does not actually observe the subject image through the viewfinder, that is, when the correction is unnecessary. Since the correction function is activated, there is a problem that power consumption increases and the battery is wasted.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and facilitates focusing and composition when observing a subject image through a viewfinder, and wastes power. It is an object of the present invention to provide a camera having an image blur correction function that can reduce unnecessary consumption.

[0007]

A camera having an image blur correction function according to the present invention includes a viewfinder optical system for guiding at least a part of a light flux from a subject for observation by a user, and a blur of the camera with respect to the subject. Provided on the optical path of the finder optical system and the blur detection means for detecting,
A correction optical system for deflecting the optical axis of the finder optical system,
Driving means for driving the correction optical system based on a signal from the shake detecting means so as to cancel the movement of the subject image due to camera shake, and a lens for detecting the movement of the lens forming the finder optical system along the optical axis direction. When movement of the lens is detected by the movement detection means and the lens movement detection means,
Drive control means for operating the drive means.

[0008]

Embodiments of the camera having an image blur correction function according to the present invention will be described below. FIG. 1 shows a camera 1 having an image blur correction function according to an embodiment.

The camera 1 receives the subject light reflected by the quick return mirror 3 after entering the subject optical image through the photographing optical system 2 for forming the subject image on the film F which is the image receiving surface and a part of the photographing optical system 2. A viewfinder optical system 4 for guiding the photographer's eyes, a shutter button 20, a control means 30 for controlling the entire camera, and an image blur correction means 40 are provided.

Further, the camera 1 includes angular velocity sensors 51 and 52 functioning as shake detecting means for detecting a shake of the photographing optical system 2 with respect to a subject, and a lens for detecting movement of a lens in the photographing optical system 2 in the optical axis direction. Movement detection means 60 is provided.

The shutter button 20 is a two-step switch, and when it is pressed one step, the photometric switch is turned on.
Then, when it is pushed in two steps, the release switch turns on. The ON / OFF information of these switches is input to the control means 30.

The angular velocity sensor 51 detects the angular velocity of the rotational movement of the camera in the vertical direction (vertical direction) of FIG. 1, and outputs to the control means 30 a voltage corresponding to the angular velocity in that direction due to camera shake or the like. The angular velocity sensor 52 is a sensor that detects the angular velocity of the rotational movement of the camera in the direction (horizontal direction) perpendicular to the paper surface of FIG. 1, and outputs a voltage according to the detected angular velocity to the control means 30.

The image blur correction means 40 is composed of a correction optical system for deflecting the optical axis of the photographing optical system 2 and a drive means for driving the correction optical system. The drive means is the control means 30.
The correction optical system is driven so as to cancel the movement of the subject image formed by the photographing optical system 2 on the film surface based on the command of, and the optical axis of the photographing optical system 2 is set to the direction perpendicular to the paper surface and the paper surface. Deflection in parallel directions independent of each other.

The control means 30 includes a lens movement detection means 60.
On the film surface F by driving the image blur correction means 40 based on the input signals from the sensors 51 and 52 when the movement of the lens is detected from the camera and during the shooting.
And correct image blur in the viewfinder field.

Although the photographing optical system 2 is shown as a single lens in FIG. 1, it is actually composed of a plurality of lenses, and a part or all of the optical axis is used for focusing or zooming. It can move in any direction. In the embodiment, the lens movement detecting means 60 detects the movement of the lens forming the photographing optical system 2 for focusing.

The focusing lens is configured to move in the optical axis direction by a known cam mechanism (not shown) by rotating the lens barrel 5. The lens barrel 5 is rotated by a motor provided in the body of the camera 1 or a lens unit, or by the photographer's own hand.

The lens movement detecting means 60 is a pinion gear 61 that meshes with a rack 5a provided on the outer circumference of the lens barrel 5.
And the slit plate 6 provided coaxially with this pinion gear
2 and a photo interrupter 63 provided with the slit plate 62 interposed therebetween. The slit plate 62 is provided with a large number of slits radially around the rotation axis. The photo interrupter 63 is composed of a light emitting portion 63a and a light receiving portion 63b that are opposed to each other with a slit plate in between, and the light receiving portion 63b outputs a periodic signal according to the light and darkness of light as the slit plate 62 rotates. To be done.

A single-lens reflex camera having an autofocus function is provided with a detecting means composed of the slit plate and the photo interrupter as described above in order to monitor the driving amount of the lens driving motor. In the embodiment, the detection means is also used as the lens movement detection means, so that the increase in the number of parts can be suppressed and the movement of the lens can be detected in both the auto focus and the manual focus. However, in order to realize the invention, it is sufficient if it can be determined that the lens is being driven. Therefore, for example, the drive current of the motor for autofocusing may be detected and used as a signal, or a portion that moves by focusing. A magnet and an MR (Magnetic Resistance) sensor, or a Hall sensor may be provided to face a portion that does not move, and output signals of these sensors may be used.

FIG. 2 shows the structure of the image blur correction means 40. The correction lens 401 that constitutes the correction optical system is fixed to the first rotating plate 420 while being fitted in the lens frame 410, and the first rotating plate 420 is provided with the second rotating plate 430 via the rotating shaft 421. Is rotatably attached to. Further, the second rotating plate 430 is rotatably attached to the substrate 440 via a rotating shaft 431 that is provided to project 90 degrees away from the rotating shaft 421 about the optical axis O of the photographing optical system. Board 440
Is fixed to the camera 1.

With the above arrangement, the correction lens 401 is
By rotating the first and second rotating plates 420 and 430, the optical axis O
It is held so as to be displaceable in the directions shown by arrows H and V in the drawing in a plane perpendicular to the plane.

The lens frame 410 has a large diameter portion 411 and a small diameter portion 412, and the small diameter portion 412 is fitted into the opening 422 of the first rotating plate 420. The rotating shaft 4 of the first rotating plate 420
21 is inserted into a shaft hole 439 formed in the second rotating plate 430. An arm 424 having a screw hole 423 is provided on the opposite side of the rotating shaft 421 with the opening 422 interposed therebetween.

A screw member 426 connected to the rotary shaft of the motor 425 via a flexible joint is screwed into the screw hole 423. The motor 425 uses the second rotating plate 4
It is fixed on 30. When the motor 425 is driven, the first rotation plate 420 is driven to rotate about the rotation shaft 421 in the direction indicated by the arrow V according to the rotation direction of the screw member 426.

The permanent magnet 4 is attached to the tip of the drive arm 424.
27 is provided, and an MR sensor 428 that detects the position of the permanent magnet 427 is provided on the second rotating plate 430 so as to face the permanent magnet 427. Control means 30
Detects the displacement of the lens 401 in the direction of arrow V based on the output signal of the MR sensor 428.

The rotary shaft 431 of the second rotary plate 430 is inserted into a shaft hole 449 formed in the substrate 440. The second rotating plate 430 has an opening 432 through which the small diameter portion 412 is inserted. The opening 432 is provided when the first rotating plate 420 is attached to the second rotating plate 430.
The size is such that the movement of the small diameter portion 412 due to the rotation of the.

A drive arm 434 having a screw hole 433 is provided on the opposite side of the rotating shaft 431 with the opening 432. A screw member 436 connected to the rotation shaft of the motor 435 via a flexible joint is screwed into the screw hole 433. The motor 435 has a board 44.
It is fixed at 0. When the motor 435 is driven,
The second rotation plate 430 is driven to rotate about the rotation shaft 431 in the direction indicated by the arrow H according to the rotation direction of the screw member 436.

The permanent magnet 4 is attached to the tip of the drive arm 434.
37 is provided, and the MR sensor 438 is arranged on the substrate 440. The control means 30 uses the MR sensor 4
A displacement of the lens 401 in the arrow H direction is detected by the output signal of 38.

The substrate 440 is provided with an opening 442 through which the small diameter portion 412 is inserted. The opening 442 has a size that does not hinder the movement of the small diameter portion 412 due to the rotation of the first and second rotating plates.

In FIG. 3, the image blur correction means 40 is viewed from the photographing optical system 2 side in a state where the lens frame 410, the first rotary plate 420, the second rotary plate 430, and the substrate 440 are combined. It is a figure. FIG. 3 shows a reference state in which the optical axis of the correction lens 401 coincides with the optical axis O of the photographing optical system. In the reference state, the center of the rotation shaft 421 of the first rotation plate, the optical axis O, the permanent magnet 427, and the MR sensor 428 are arranged on the straight line a. Similarly, the center of the rotation shaft 431 of the second rotation plate 430, the optical axis O, the permanent magnet 437, and the MR sensor 438 are arranged on the straight line b.

FIG. 4 is a block diagram for explaining input / output signals of the CPU 31 constituting the control means 30 described above.
The ON / OFF information of the metering switch 21 and the release switch 22 which are linked to the shutter button 20 is represented by a 1-bit digital pulse of the port PI1 of the CPU 31,
Input to PI2. The voltage outputs of the angular velocity sensors 51, 52 are supplied to the A / D conversion ports AD1, AD2 of the CPU 31,
The voltage outputs from the MR sensors 428 and 438 are supplied to the A / D conversion ports AD3 and AD4, and the photo interrupter 6
The output signals of 3 are respectively input to the port PI3 which detects the pulse input.

D / A output ports DA1 and D of the CPU 31
A motor 425 that drives the first rotary plate 420 and a motor 435 that drives the second rotary plate 430 are connected to A2 via motor drive circuits 461 and 462, respectively. The CPU 31 uses the motor 4 to determine the movement amount of the correction lens required to correct the image blur based on the above-mentioned input signal.
25, the drive amount of the motor 435 is converted and calculated, and the voltage corresponding to the drive amount is output from the ports DA1 and DA2.

FIG. 5 is a flow chart showing only the part necessary for explaining the control of the image blur correction, taken out from the control sequence of the camera of this embodiment.

It should be noted that although two angular velocity sensors are actually used, their output values are processed independently of each other and used to drive the motors corresponding to the respective sensors. Therefore, in order to avoid duplication of description, only one image blur correction process is shown in the flowchart of FIG.

When the power of the camera is turned on and control is started, the counter A used for calculation is initialized to 0.
(S1) Wait for the 1ms timer to expire
(S2), the correction lens drive control subroutine is executed
(S3), ON / OFF of the photometric switch is determined (S4). When it is determined that the photometric switch is OFF, the process returns to S2, so that the drive control of the correction lens is executed at intervals of 1 ms while the photometric switch is OFF.

In the correction lens drive control subroutine,
As shown in FIG. 6, it is determined whether or not a signal from the photo interrupter 63 is generated (S20), and when it is generated, that is, when the focus lens is moving, the counter A is set to "20". Value is set (S21).
If the photo interrupter signal is not generated,
It is determined whether or not the value of the counter is 0 (S22), and if not 0, the value of the counter A is decremented (S23).

When the value of the counter A is not 0, that is, when the signal of the photo interrupter is being output or before 20 ms have passed since the signal was not output,
The shake amount is detected from the output of the angular velocity sensor, the drive amount is calculated (S24), and the correction lens is driven (S25).

On the other hand, when the value of the counter A is 0, that is, when 20 ms or more elapses after the signal of the photo interrupter is not output, the driving of the correction lens is stopped (S26). The control using the counter A is executed not to stop the image blur correction immediately after the movement of the lens is no longer detected, but to stop it after a predetermined time.

By the way, in a camera having an autofocus function, focus detection is generally performed by turning on a photometric switch, and the focus lens is driven by a motor based on the result. Therefore, when the autofocus function is used, the movement of the lens is not detected in S3, and the correction lens is not driven. However, when manually adjusting the focus, it is not always necessary to focus on the shutter button after putting the hand on it, so there is a demand to make the shake correction function even before the photometric switch is turned on. The process of S3 is intended to facilitate focusing and composition determination by assuming the case of manual focus and operating the image blur correction function even when manual focusing is performed.

However, after moving the focusing lens, it may be considered to take the eye away from the viewfinder, and in such a case, continuing the image blur correction results in waste of power. Therefore, in the embodiment, the lens movement is not detected for a certain period of time, that is, 20 times in this example.
When the ms period has elapsed, the image blur correction is stopped.

When the photometric switch is turned on, the timer for 1 ms is counted up (S5), photometry is performed, and the aperture value, exposure time, etc. are calculated (S5).
6). Here, the above-mentioned correction lens drive control subroutine is executed again (S7).

When the photometric switch is turned on, the processes of S6 and S7 are repeatedly executed every 1 ms until the release switch is turned on. When the metering switch is turned off, S2
The process is repeated by returning to.

When it is determined that the release switch is turned on (S8), the shake correction is stopped so that the correction lens is not driven unnecessarily in response to the vibration before exposure such as driving the mirror.
(S9), the aperture is stopped down to a predetermined aperture value, the quick return mirror is raised, the shutter runs, and exposure is started (S10).

During exposure, detection and calculation of the amount of blurring (S12) and driving of the correction lens (S13) are repeated every 1 ms (S11) until the exposure time ends. When it is determined that the exposure time has elapsed (S14), the shutter is closed, exposure end processing such as mirror down, aperture opening, etc. is performed (S15), and the correction lens is set to the neutral position (corrected with the optical axis of the photographing optical system and corrected). The position is returned to the position where the optical axis of the lens coincides (S16), and the sequence ends. If the camera is powered on,
After this, the process returns to the beginning (S1) of the sequence again.

In the above description of the image blur correction sequence, the correction only in the V direction has been described. However, in reality, similar correction processing is executed in each of the V and H directions.

The camera 1 of the embodiment is a single-lens reflex camera that guides the light flux from the subject to the film surface F and the eyes of the photographer through a common optical path. In this case, the finder optical system 4 is defined as a system including the taking optical system 2 as a part thereof. Therefore, detecting the movement of the focusing lens of the photographing optical system is included in the concept of detecting the movement of a part of the lenses of the finder optical system.

The camera according to the invention is characterized in that at least the image blur of the finder optical system is corrected when the movement of the lens constituting a part of the finder optical system in the optical axis direction is detected. It is not necessary to correct the image blur of the photographing optical system as in the embodiment. That is, in a camera in which the finder optical system and the photographing optical system are provided independently, it is possible to correct only the image blur of the finder optical system.

However, in the case of a single-lens reflex camera, if the correction optical system is provided in the photographing optical system, the blurring of the viewfinder image and the image on the film surface can be corrected at the same time, and the autofocus function is also provided. In the case of a camera equipped with, there is an advantage that the blurring of the image on the autofocus sensor can be corrected, and accurate focus detection can be performed. Further, in the above-described embodiment, the movement for focusing of the photographing optical system is detected and the image blur correction is started, but the movement for zooming may be detected and started in the same manner.

[0047]

As described above, according to the present invention, when adjusting the focus through the viewfinder, it is possible to correct the blur and improve the visibility of the subject image.
Focusing and composition determination become easy. Further, by detecting the movement of the lens in the optical axis direction and then causing the image blur correction to function, it is possible to suppress unnecessary power consumption as compared with the case where the image blur correction immediately functions when the power switch is turned on. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a camera having an image blur correction function according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a correction lens driving mechanism of the camera of the embodiment.

FIG. 3 is a front view of the drive mechanism of FIG. 2 viewed from the side of a photographing lens.

FIG. 4 is a block diagram showing a configuration of a control system of the camera of the embodiment.

FIG. 5 is a flowchart showing a control sequence of the camera of the embodiment.

FIG. 6 is a flowchart showing a subroutine of correction lens drive control of FIG.

[Explanation of symbols]

1 camera 2 Shooting optical system 4 Finder optical system 20 shutter button 21 Photometric switch 22 Release switch 30 control means 31 CPU 40 Image blur correction means 401 correction lens 420 First rotating plate 430 Second rotating plate 440 substrate 51,52 Angular velocity sensor 60 Lens movement detecting means

Claims (6)

(57) [Claims] 1. A finder optical system provided in a camera for guiding at least a part of a light flux from a subject for observation by a user, a blur detecting unit for detecting blur of the camera with respect to the subject, and the finder optical system. And a correction optical system for deflecting the optical axis of the finder optical system, and the correction optical system based on a signal from the shake detection means so as to cancel the movement of the subject image due to the shake of the camera. Driving means for driving the lens, a lens movement detecting means for detecting movement of the lens constituting the finder optical system along the optical axis direction, and the driving means for moving the lens when the lens movement detecting means detects the movement of the lens. Drive control means for activating the means, wherein the drive control means is configured to drive the drive after a certain period of time after movement of the lens is no longer detected. A camera having an image blur correction function characterized by stopping the means. 2. The camera having an image blur correction function according to claim 1, wherein the viewfinder optical system includes a photographing optical system for forming a subject image on an image pickup surface as a part thereof. 3. The camera having an image blur correction function according to claim 2, wherein the correction optical system is provided in the photographing optical system. 4. The camera having an image blur correction function according to claim 2, wherein the lens movement detection means detects movement of a focusing lens group in the photographing optical system. 5. The image blur correction function according to claim 4, wherein the lens movement detecting means detects movement of the lens by detecting rotation of a lens barrel holding the lens. Camera with. 6. The camera having an image blur correction function according to claim 1, wherein the lens movement detection means detects movement of a focusing lens group in the finder optical system.