JPH0651384A - Shaking prevention device for camera - Google Patents

Abstract

PURPOSE:To correct the blurring of an image even when the moving speed of an object is high by deciding an exposure time according to the moving speed of the object in order to correct the blurring of an image caused by the movement of the object or a photographing device. CONSTITUTION:The moving speed of the object image is detected based on the output of the image blurring detected by a camera shaking detection part 25. Then, correction driving quantity required for preventing the blurring of the image is calculated by a CPU 15 based on the moving speed of the object image. On the other hand, the driving threshold value of the correction driving quantity and the photometry value of the brightness of the object outputted from a photometry circuit 10 are calculated by the CPU 15 together with the correction driving quantity. Then, the exposure time based on the correction driving quantity, the driving threshold value and the photometry value is calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera shake preventing device for a camera, a video camera, and the like, for correcting image shake caused by movement of a subject or a photographing device.

[0002]

2. Description of the Related Art Conventionally, as a blur correction device in a photographing device, for example, Japanese Patent Publication No. 1-35957,
The angular velocity sensor is used to detect information about the rotation of the image capturing device due to camera shake (camera shake) of the photographer supporting the camera, and based on that information, the entire lens barrel or part of the optical system, or imaging There is one that moves the part to correct the blur. Further, there is one that corrects the image blur by detecting the image blur from the output from the image pickup unit composed of a photoelectric conversion element and controlling the transfer timing of the charge of the image information accordingly.

[0003]

As described above, in the case of a camera which performs the blur correction by obtaining the moving speed of the subject, the blur correction system is mainly driven to correct the blur during exposure. However, since the driving range is limited, there is a problem in that all the blur cannot be corrected depending on the blur amount and the exposure time.

The present invention has been made in view of the above points, and detects a moving speed of an object on the image plane to prevent the object image from being shaken during exposure. It is an object of the present invention to provide a camera shake prevention device capable of correcting camera shake even when the moving speed of a subject of the camera that drives the camera is fast.

[0005]

That is, as shown in FIG. 1, a camera shake prevention apparatus according to the present invention includes an image shake detection means 1 for detecting image shake and an output of the image shake detection means 1. A subject image moving speed detecting means 2 for detecting the moving speed of the subject image based on the above, a correction driving amount calculating means 3 for calculating a correction driving amount necessary for preventing image blur based on the subject image moving speed, and the above A drive amount limit value output means 4 for outputting the drive limit value of the correction drive amount, a photometric means 5 for measuring the brightness of the subject and outputting a photometric value, and a correction drive amount, the drive limit value and the photometric value And the exposure time calculating means 6 for calculating the exposure time.
Even if the moving speed of the subject is high, the blur can be corrected.

[0006]

In the camera shake prevention apparatus according to the present invention, when the object image moving speed detecting means 2 detects the moving speed of the object image based on the output of the image shake detected by the image shake detecting means 1, The correction drive amount calculation means 3 calculates the correction drive amount required to prevent image blur based on the subject image moving speed. On the other hand, the drive limit value of the corrected drive amount output from the drive amount limit value output means 4 and the photometric means 5
The photometric value of the brightness of the subject output from the above is calculated by the exposure time calculation means 6 together with the above-mentioned correction drive amount, and the exposure time based on the correction drive amount, the drive limit value and the photometric value is calculated. This makes it possible to correct the blur even if the moving speed of the subject is high.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram schematically showing the structure of a camera to which the camera shake preventing apparatus according to the present invention is applied. In the figure, this camera comprises a photometric circuit 10, a photographing lens 11, a focus detection optical system 12, an area image sensor 13, an interface circuit 14, a CPU (central processing unit) 15, a ROM (read only memory) 16 , Lens ROM17, lens drive circuit 18, lens drive motor
18a, magnification information output unit 19, slit 20, light-emitting diode 21a constituting a photo interrupter, photodiode
21b, the display device 22, the mode setting unit 23, the image stabilizing device 24, the mechanical shake detection unit 25, and the first release switch SW1,
It is composed of a second release switch SW2 and the like.

The photometric circuit 10 measures the subject brightness,
From the brightness signal and the sensitivity information of the film loaded in the camera, the exposure amount information such as the exposure time and the aperture value at the time of shooting is calculated and output.

The focus detection optical system 12 receives a light beam (image information) from a subject (not shown) through the taking lens 11 and focuses the subject to form an image of the subject captured by the taking lens 11. It is something to detect. The area image sensor 13 photoelectrically converts an image of a formed object into an electric signal (video signal), and is driven by the interface circuit 14. Also the interface circuit
14 converts the electric signal (analog signal) from the area image sensor 13 into a digital signal and outputs it to the CPU 15.

The CPU 15 controls the operation of the entire camera. For example, the CPU 15 calculates the object distance based on the output of the area image sensor 13, and the focusing, non-focusing, and the like in the display device 22. The control of the display of the state and the like, the control of the image stabilizing device 24, etc. are performed. As the vibration isolator 24, for example, the vibration isolator described in Japanese Patent Application No. 2-257909 may be used.

Further, the ROM 16 stores a shift amount (two image intervals) of in-focus points in a plurality of areas for focus detection. The lens ROM 17 is provided in the lens barrel and is used for focus detection and focus adjustment such as conversion coefficients for converting the F number of the lens and the image shift amount into the defocus amount and the drive amount of the focus adjustment optical system. It stores various necessary data.

The lens driving circuit 18 drives the lens driving motor 18a under the control of the CPU 15 to move the position of the focus adjusting optical system of the photographing lens 11.

Normally, in the AF (autofocus) operation for detecting the subject distance and driving the taking lens 11 based on the distance information, the driving amount of the taking lens 11 is set to the CPU 15.
Need feedback to. In this case, the movement amount of the photographing lens 11 actually moved is determined by the driving motor 18a.
It is common to substitute the number of revolutions. Therefore, here, the slit 20 is obtained by counting with the photo interrupter. That is, when the lens driving circuit 18 operates and the driving motor 18a is rotated, the slits 20 provided at equal intervals in the rotating member of the lens barrel are rotated. Then this slit 20
Passes through between the light emitting diode 21a and the photodiode 21b, which are arranged opposite to each other, so that the rotation speed is C
Counted by PU15. After that, when the count number reaches a predetermined value, the drive motor 19 is controlled to stop rotating. The first release switch SW1 and the second release switch SW2 are switches for AF operation.

Further, the magnification information output section 19 outputs the focal length of the lens and the absolute distance value necessary for obtaining the photographing magnification β. The mode setting unit 23 outputs a camera mode set by the photographer, flow amount information described later, and the like.

Further, the mechanical shake detecting section 25 has a vibration sensor for mechanical shake (mechanical shake) such as an angular velocity sensor or an acceleration sensor attached to the camera body. From the outputs of these sensors, the focal length of the lens, and the subject distance, the moving speeds Vcx and Vcy of the subject on the photographic screen caused by the mechanical shake are detected in real time.

The moving speeds Vx, V of the image from the video signal
The method to obtain y and Vcx, Vcy in the mechanical shake detection unit
Since the method for obtaining is detailed in, for example, Japanese Patent Application No. 2-257909, description thereof will be omitted here.

3 and 4 are a sectional view and a schematic perspective view schematically showing a single-lens reflex camera to which the image stabilizing device 24 is applied. 3 and 4, the single-lens reflex camera comprises a camera body 26 and a taking lens 27. This taking lens 27 is a taking optical system.
28, a first correction optical element 30 that is configured to be rotatable about an axis 29 and that corrects vibrations in the yz plane, and a disk-type ultrasonic wave that drives the first correction optical element 30. A motor 31, an encoder 32 for detecting the rotation state of the first correction optical element 30, and a second correction optical element for correcting vibration in the xz plane which is rotatable about an axis 33. It has a disc type ultrasonic motor 35 for driving the second correction optical element 34, and an encoder 36 for detecting the rotation state of the second correction optical element 35. Further, the photographing lens 27 has an electric circuit section 37 for driving the disc type ultrasonic motors 31 and 35, and a photographing lens side contact 38 for exchanging signals between the camera body 26 and the photographing lens 27. Is also equipped.

The encoder 32 is a first correction optical element.
Drum 32 ₁ that rotates according to the rotation of 30 and this drum 32
₁ magnetic sensor for detecting a rotational state of (such as magnetic heads, hereinafter referred to as MR sensors) 32 and _2, an optical sensor (not shown) for detecting the end of rotation of the drum 32 ₁ (photo-reflector or the like, less PR It is abbreviated as a sensor). Similarly, the encoder 36 includes a drum 34 ₁ that rotates in response to rotation of the second correction optical element 34,
MR sensor for detecting the rotating state of the drum 34 _1.
34 ₂ and a PR sensor (not shown) for detecting the end of rotation of the drum 34 ₁ .

On the other hand, the camera body 26 includes a quick return mirror 39, a focus detection optical system and a finder optical system 40.
And an eyepiece lens 41, an electric circuit section 42 for performing signal processing, calculation of camera shake amount, etc., and a camera body side contact 43 for exchanging signals between the camera body 26 and the taking lens 27. It is configured. Also, the camera body
26 is set to y to detect the mechanical shake amount of the camera.
An angular velocity detector 44 including an axial angular velocity detector 44 ₁ and an x-axis angular velocity detector 44 ₂ is mounted.

The y-axis angular velocity detecting section 44 ₁ is provided in the y-axis of the camera.
It detects the angular velocity of the shake of rotation about the axis. The blurring due to the rotation around the y-axis becomes a factor that causes the image blurring in the x-axis direction on the film. Moreover, x-axis angular velocity detection unit 44 ₂ is for generating the angular velocity of blurring similarly camera x-axis rotation. The blurring due to the rotation around the x-axis becomes a factor that causes the image blurring in the y-axis direction on the film. These y-axis and x-axis angular velocity detectors 44 ₁ and
Camera shake information 44 ₂ has detected is transferred to CPU15 in an electrical circuit portion 42 of the camera body 26.

Further, the electric circuit system of the vibration isolator 24 will be described with reference to FIG. In FIG. 5, the same parts as those in FIGS. 3 and 4 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 5, the CPU 15 has a photographing lens 27.
A lens ROM 17 that stores information regarding the above, drive control units 45 and 46 for driving the disk-type ultrasonic motors 31 and 35, encoders 32 and 36, and a storage unit 47 that stores various programs are coupled. . Also, CP
U15 includes the camera shake information detected by the y-axis and x-axis angular velocity detectors 25 ₁ and 25 ₂ and the image movement information in the x-axis direction and the y-axis direction among the axial directions shown in FIG. It is being supplied.

Based on the image movement signal thus supplied and various constants and programs stored in the lens ROM 17 and the storage unit 47, the CPU 15 uses the first and second correction optics necessary for canceling the image movement. The angular velocities of the elements 30 and 34 are calculated, and the calculated angular velocities are sent to the drive control units 45 and 46. These drive control units 45 and 46 drive the disk-type ultrasonic motors 31 and 35 based on the captured angular velocity to correct the image blur.

Next, consideration will be given to the focal length and the exposure time at the time of photographing when the blur is corrected.

Now, let us say that the control exposure time for actual photographing is S ₀ . In the case of a camera having a focal plane shutter, the time required for actual photographing is the one that takes into account the traveling time S ₁ of the two shutter curtains. The exposure time in consideration of the running time S ₁ is S.

S = S ₀ + S ₁ (1) It is during this time S that the image stabilization device 24 as the image blur correction means needs to operate. The actual time S ₁ is about 5
It is about msec, which is usually considerably shorter than the exposure time required for blur correction. Therefore, the above equation (1) may be approximated as S = S ₀ . For a lens shutter or the like, S = S ₀ .

Further, the moving speed of the image of the object (Vox, Vo
The basic drive speed of the vibration isolator 24 is determined following y). Therefore, the amount of displacement (Vox, Voy) of the image due to the movement of the subject corrected by the image stabilizing device 24 during the time S is Vox = Vox · S Voy = Voy · S (2)

By the way, the moving speed of the subject image is (Vox,
Voy), but if the corresponding moving speed of the subject in the direction parallel to the screen is (Vvx, Vvy), the relationship of Vox = β · Vvx Voy = β · Vvy (3) holds depending on the imaging magnification β. To do.

Further, assuming that the shooting distance is R and the focal length is f, the shooting magnification β is approximately expressed as β = f / R (4), so the above equation (2) is expressed as Xox = S · Vvx · f. / R Xoy = S · Vvy · f / R (5)

The limit of the movement of the image that can be corrected by the blur correction means is (XLx, XLy) for each of the xy axes. Further, the amount of background flow intended by the photographer at the time of panning is set to (XRx, XRy) for each of the xy axes. It is impossible to correct a blur larger than the range in which blur can be corrected, and if it is attempted, it will be inappropriate blur correction. Therefore, when XLx> Xox, some measure is required.

Here, for the sake of simplicity, let us consider only the x-axis and consider the above equation (5). The camera cannot freely control the movement and distance of the subject. However, with regard to the exposure time S and the focal length f, it is possible to change the setting and operate because it is a problem inside the camera.

When it is possible to correct the shake within the shake correction limit by changing the exposure time S, Xox = XLx
Then, from the above formula (5), the exposure time S may be determined as S = XLx / Vox (6). The control exposure time S ₀ is determined from this S.

When the amount of background flow intended by the photographer is set during panning photography, Xox = XRx and S = XRx / Vox (7) from the above equation (5) Should be set. Further, similarly, the control exposure time S is set.

After the exposure time S is thus determined, the control aperture value at the time of exposure is determined based on the output of the photometric circuit 10 in order to maintain proper exposure.

When a subject moves and image movement occurs, the amount of image movement changes depending on the focal length even if the same subject moves. Therefore, it is possible to facilitate proper blur correction by setting the exposure time according to the focal length.

When the focal length of the taking lens can be changed,
In order to enable blur correction within the blur correction limit by changing the focal length f, the original focal length is f ₀ , the changed focal length is f ₁ , and the exposure time S is set by a predetermined method. If it is determined, Xox = S · Vvx · f ₀ / R (8) XLx = S · Vvx · f ₁ / R (9) From, f ₁ / XLx = f ₀ / Xox (10) Therefore f _The focal length can be determined as ₁ = f ₀ · XLx / Xox (11).

When setting the amount of background flow intended by the photographer during panning photography, the focal length may be determined as f ₁ = f ₀ · XRx / Xox (12).

When the focal length is changed, the moving speed of the image of the subject changes, so the moving speed (Vox, Voy) of the image of the subject used for blur correction is also changed according to the ratio of the focal lengths. To do.

Next, the movement of the object on the image will be considered.

Since the image movement information obtained from the video signal is information relating to the relative movement of the subject and the camera,
It consists of an image movement component due to the movement of the subject and a component due to mechanical camera shake or movement. Further, the information on the movement of the image due to the mechanical shake obtained by the mechanical shake detection unit 25 is composed only of the components due to the mechanical shake and movement of the camera. Therefore, the image moving speed (V
x, Vy) and the image moving speed (Vcx, Vcy) obtained from the camera shake of the camera, the moving speed (Vox, Voy) of the image caused by the movement of the subject can be obtained. Becomes

Here, Vx, Vcx, and Vox are x, respectively.
It is an image movement velocity component in the axial direction. Also, Vy, Vcy, V
oy is an image moving velocity component in the y-axis direction. Specifically, it can be calculated as Vox = Vx-Vcx Voy = Vy-Vcy (13).

Next, the operation of the entire camera will be described with reference to the overall sequence flowchart of the CPU 15 shown in FIG.

First, after the power is turned on and the program is started, the initialization program is executed in step S1 to perform various initial setting operations. this is,
For example, the timer 15 of the CPU 15, the setting of the interrupt condition of the CPU 15, the setting of the I / O port, the setting of the stack pointer, and the like, the hardware-like or software-like resetting operation of the CPU 15, and the CPU 15 are arranged outside the CPU 15. Detecting the operating status of various cameras from the non-volatile memory, the operation of reading data such as the number of film frames, the initial setting, initial operation, and status of each electric circuit and mechanical mechanism controlled by the CPU 15. And so on.

Next, in step S2, the key input routine is executed to read the input switches of the camera, and the setting mode and data of the camera corresponding to each operation are set according to the operation state of those switches. If the key input is executed, the process proceeds to step S3 and the display routine is executed. Here, the display of the operating state of the camera, data and the like using a display device is performed. Then, in step S4, a photometric routine is executed. In this photometric routine, the subject brightness signal from the photometric circuit 10 and the exposure time information and aperture value information that are controlled for actual shooting are calculated and output.

When photometry is completed in this way, step S
At 5, the first release switch SW1 is read and judged. If the first release switch SW1 is off, that is, if it is not operated, the process returns to step S2. On the other hand, when the first release SW1 is on, that is, in the operated state, the process proceeds to step S6 and the distance measuring subroutine is executed. In this distance measurement routine, information regarding the focus shift of the subject in the optical axis direction is obtained. Here, if the focus shift is small enough to be determined to be in focus, the focus determination flag is set. On the other hand, if it is determined that the focus shift is unacceptable, the focus determination flag is cleared. The focus determination flag is also cleared when it is determined that the subject cannot be focused due to insufficient brightness of the subject, insufficient contrast, or the like.

Next, in step S7, the focus determination flag is used to determine the focus and separate the operation. Here, when the focus is not achieved (focus determination flag = 0),
If the focus is reached (focus determination flag = 1), the process proceeds to step S9. Step S7
If it is determined in step S8 that the subject is out of focus and the process branches to step S8, the AF driving subroutine is executed in step S8. In this subroutine, step S
The focus adjustment optical system of the taking lens 11 is driven so as to focus on the subject based on the focus shift information obtained in the distance measurement routine of 6. Then, after this, the process returns to step S2.

If it is determined in step S7 that the subject is in focus, the process proceeds to step S9 and the image blur detection subroutine (VOCAL) is executed.

Here, prior to photographing, the information corresponding to only the movement of the subject is obtained as described above, and the movement information of the image due to the mechanical blur is detected from the mechanical blur of the camera which occurs momentarily during the photographing, and it is detected. When correcting the blur, it is possible to cancel the blur of the mechanical camera and cancel the image blur due to the movement of the subject by performing the blur correction in consideration of the movement information of the subject obtained earlier. is there. The speed of image movement (V
FIG. 7 shows a subroutine for obtaining ox, Voy).

FIG. 7 shows an image blur detection subroutine. First, at step A1, the image blur velocity (Vx, Vy) based on the image information is detected. Then step A
After the camera shake speed is detected at 2, the focal length (f) of the taking lens 11 is detected at step A3. And
In step A4, the image moving speed (Vcx, Vcy) due to camera shake is calculated, and in step A5, the image moving speed (Vox, Voy) due to subject movement is calculated as in the above equation (13).

When the image blur detection is completed in this way, the flow advances to step S10 to execute mechanical blur detection. As a result, the image blurring speed (V
cx, Vcy) is required.

Next, at step S11, a subroutine for subject image movement detection is executed. This subroutine
The speed (Vox, Voy) of the image movement due to the movement of the subject is obtained, and is schematically shown in FIG.

Here, the image moving speed Vox due to the movement of the object is calculated in step B1, and then the image moving speed Voy is calculated in step B2 according to the above-mentioned equation (13).

9 and 10 are time charts for obtaining the speed of image movement due to the above-described image movement. For example, FIG. 9 is a time chart in the case of the above-described algorithm described with reference to FIG. 8, in which video signals are read at the times (t ₂₁ , t ₂₂ ) indicated by the timing of distance measurement. And at time t ₂₂ ,
Subsequently, the image moving speed (Vx, Vy) is calculated. Then, at the time t _23, the mechanical camera shake was measured, the movement speed of the image by Mekabure (Vcx, Vcy) is obtained. Next, at time t ₂₄ , (VLx, VLy)
After detection of the object, the speed of image movement (Vox, V
oy) is calculated. Here, Δt ₂₁ and Δt ₂₂ are time t
It represents _21, t integration time of the video signal to be read at ₂₂ (sample time length).

Now, when considering the position of the object obtained at time t ₂₁ , it is considered that it is the average position within Δt ₂₁ hours. Similarly, the information on the position of the object obtained at time t ₂₂ is an average position within Δt ₂₂ hours. Therefore, the moving speed of the object image obtained at the time t ₂₂ is considered to be an average value between the times t ₂₀ and t ₂₂ . Image movement speed (Vcx, Vc due to camera mechanical shake)
By taking this point into consideration when obtaining y), it becomes possible to increase the accuracy of the image movement speed (Vox, Voy) due to the movement of the image of the subject.

FIG. 10 shows an example thereof, in which (Vcx, Vcy) or the mechanical shake amount is measured several times during the time t _{20 to} t ₂₂ , and the average value thereof is calculated at the time t _23. Ask. The image moving speed (Vox, Voy) due to the mechanical shake of the camera is obtained based on this average value, and the image moving speed due to the movement of the object is calculated at the time t ₂₄ from the average value and the image moving speed (Vx, Vy). The speed (Vox, Voy) of is calculated. In this case, it is not necessary to perform the mechanical shake measurement for each of the x-axis and the y-axis at the same time. For example, the mechanical shake may be performed at alternate timings to reduce the time required for one measurement.

When the object image movement detection is completed, the process proceeds to step S12, and the exposure time / focal length setting subroutine is executed. FIG. 11 shows this exposure time / focal length setting subroutine. First, the exposure time S is calculated in step C1. This, as mentioned above,
Considering the limit amount of image movement that can be corrected by the blur correction means for each of the x-axis and the y-axis (XLx, X
Ly). Then, using the moving speed (Vox, Voy) of the image due to the movement of the subject detected by the above-mentioned subroutine for detecting the subject image movement, a calculation of Sx = XLx / VoxSy = XLy / Voy (14) is performed. These are x-axis and y-axis,
This is the time when the entire image correctable range is used. Since it is desired to perform correction within the limits of each of the x-axis and the y-axis, the actual correction time S is the shorter of Sx and Sy, that is, S = Sx (Sx≤Sy) S = Sy (Sx> Sy) ( It is determined by calculating the condition judgment in 15).

Next, in step C2, considering the time data S ₁ required for the traveling of the two shutter curtains, the time S _{0 at} which each part of the film is actually exposed is S ₀ = S−S ₁ ... (16) is calculated as. The data of S ₁ may be stored in the storage unit of the main body and read and used, or may be written in the program as an immediate value. Further S ₁
It may be possible to approximate = 0.

Next, in step C3, step S
The exposure amount obtained in the photometric routine of No. 4 is read. When the exposure amount is expressed by a logarithmic compression value, if the logarithmic compression value of the aperture value is set to (AV) using a known Apex arithmetic expression, AV = (exposure amount) −TV (17) (TV = log ₂ (1 / S ₀ ): Shutter speed logarithmic compression value) can be calculated (step C4). This A
The V value and the TV value are used for exposure control during shooting by a known method.

By the way, if the AV value obtained here is a value that cannot be actually controlled, that is, if it means a particularly small aperture, that is, if the aperture cannot be interlocked in step C5, the exposure time and focal length are set as they are. Without exiting the subroutine, the process proceeds to the next step C6. On the other hand, if the photographing lens for which the focal length cannot be set in step C5, that is, the single focal length lens or only the manual focal length can be set, the routine is exited without setting the focal length here.

[0061] Where possible the focal length adjustment, the process proceeds to step C6, f ₀ the current focal length, the focal length of the changed When _{f 1, f 1 x = f} 0 · XLx / (S · Vox ) F ₁ y = f ₀ · XLy / (S · Voy) (18) is calculated. Then, in step C7, f ₁ x, f
Drive the zoom to change the focal length using the larger of ₁ y. After zooming, the amount of movement of the image due to the movement of the subject is corrected as follows: Vox = (f ₁ / f ₀ ) · Vox Voy = (f ₁ / f ₀ ) · Voy (19), and the process returns to step C1. Alternatively, the subroutine may be exited as it is.

When the exposure time / focal length setting is completed in this way, the process proceeds to step S13 to read and determine the state of the first release switch SW1. here,
If the first release switch SW1 is in the off state, that is, if scanning is not being performed, the process returns to step S2. If the first release switch SW1 is turned on, that is, if the operation is continued, it is determined in the next step S14 whether or not the second release is prohibited by the shake detection subroutine and the second release prohibition flag is set. To judge. If prohibited here, the process returns to step S9.

On the other hand, if the second release is permitted, the process advances to step S15 to read and determine the state of the second release switch SW2. If the second release switch SW2 is off, that is, if it is not operated, the process returns to step S9. On the other hand, when the second release switch SW2 is operated, the operation shifts to the second release operation.

At step S16, a subroutine for predicting a moving body is executed, and if necessary, the focus adjustment optical system is driven so as to correct the movement of the subject during the exposure operation in the optical axis direction, and the focus shift is corrected. I do. It should be noted that the moving body prediction drive here is the speed V of the subject (object) in the optical axis direction.
This is to predict the movement of the subject during the release time lag from z and drive the focus adjustment optical system of the taking lens 11 so that the subject is in focus during the exposure on the film surface. A known method is used for this motion predictive driving,
Since it is not the gist of the present invention, its detailed description is omitted here. That is, in step S16, the focus adjustment optical system 12 is driven to correct the focus shift so as to correct the movement of the subject during the exposure operation in the optical axis direction, if necessary.

Next, after exposure is started in step S17, image stabilization is started in step S18. Next, in step S19, the image stabilization control subroutine is executed.

The movement of the object generally does not occur at such a high frequency. In particular, in the case of panning, the movement of the image of the subject occurs at a substantially constant speed. Therefore, in the image stabilization control during exposure, basically, control is performed to prevent blurring at a uniform speed so as to cancel the moving speed of the image of the subject obtained immediately before the start of exposure. Further, the mechanical shake of the camera due to the vibration of the human body is detected, the movement of the image due to this is detected, and the shake prevention control is performed so as to cancel it. That is, the moving speed (Vox, Voy) of the image of the object obtained prior to the exposure and the moving speed (Vcx, Vy) of the image due to the mechanical shake of the camera that is sequentially detected during the exposure.
(Cy) and blurring are the blurring during exposure. Therefore, image stabilization control is performed in real time so as to cancel this added blur during exposure.

FIG. 12 is a flow chart showing the outline of image stabilization control. First, in step D1, mechanical shake detection is performed based on the above-described principle, and the moving speed (Vcx, Vcy) of the image due to successive mechanical shakes is detected. To do. Then, in step D2, the moving speed (Vo
x, Voy) is read. After that, an addition operation of (Vox + Vcx) is performed for the shake in the x-axis direction (step D3), and then an addition operation of (Voy + Vcy) is performed for the shake in the y-axis direction (step D4). This (Vox + Vcx) and (V
oy + Vcy) represents the image blur that should be prevented in real time during exposure. In this way, based on the shake information obtained by addition, the image stabilizing device 24 as the shake correcting means is driven so as to cancel it (step D).
5). The above series of operations is repeatedly performed during exposure.

In this way, if the image stabilization control is performed,
In step S20, it is determined whether the exposure is completed. If the exposure has not ended, step S19
Returning to step S21, if it is completed, the process proceeds to step S21. The CPU 15 such as an exposure time timer determines whether the exposure has ended.
A signal generated internally may be used, or a switch or the like for detecting the end of the exposure operation that is interlocked with the shutter device may be provided to detect the state thereof.

If it is determined in step S20 that the exposure has been completed, the process proceeds to step S21, and an image stabilization reset routine for resetting the image stabilization mechanism mechanism is executed. Here, the image stabilization mechanism is set at a predetermined position for the next shooting. Next, in step S22, an exposure mechanical reset routine is executed.
By executing this exposure mechanical reset, the shutter is charged, the aperture is driven to open, the quick return mirror 39 is raised, and one frame of film is wound for the next shooting. Then, the process returns to step S2 and the above-described operation is repeated.

In this way, when performing follow shot photography, even if the drive range is limited when moving the optical system,
Image blur correction that does not cause unnecessary image blur or inappropriate image blur can be performed. Further, the photographer himself / herself can freely set the effect amount of the follow shot, and the photographer's intention can be more expressed.

[0071]

As described above, according to the present invention, the camera for driving the image blur correction system so as to detect the moving speed of the object on the image plane and prevent the object image from being shaken during exposure is provided. In this case, it is possible to provide a camera shake prevention device capable of correcting shake even if the moving speed of the subject is high.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a camera shake prevention device according to the present invention.

FIG. 2 is a block diagram schematically showing the configuration of a camera to which the camera shake prevention device according to the present invention is applied.

FIG. 3 is a sectional view schematically showing a single-lens reflex camera to which the image stabilization device of FIG. 2 is applied.

4 is a schematic perspective view schematically showing a single-lens reflex camera to which the image stabilization device of FIG. 2 is applied.

5 is a block diagram showing an electric circuit system of the image stabilization device of FIG.

6 is a sequence flowchart illustrating the overall operation of the CPU of FIG.

7 is an image blur detection (V
This is a subroutine for explaining OCAL).

FIG. 8 is a subroutine for explaining subject image movement detection in the flowchart of FIG.

FIG. 9 is a time chart showing an example of a case where the speed of image movement due to image movement is obtained in the subroutine of FIG.

FIG. 10 is a time chart showing another example of a case where the speed of image movement due to image movement is obtained in the subroutine of FIG.

FIG. 11 is a subroutine for explaining exposure time / focal length setting in the flowchart of FIG.

FIG. 12 is a subroutine for explaining the image stabilization control in the flowchart of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image blur detection means, 2 ... Subject image moving speed detection means, 3 ... Correction drive amount calculation means, 4 ... Photometric means, 5 ... Drive amount limit value output means, 6 ... Exposure time calculation means, 10 ... Photometric circuit, 11 ... Photographic lens, 12 ... Focus detection optical system, 13 ... Area image sensor, 14 ... Interface circuit, 15 ... CP
U (central processing unit), 16 ... ROM (read only memory), 17 ... Lens ROM, 18 ... Lens drive circuit, 18a
... Lens drive motor, 19 ... Magnification information output unit, 20 ... Slit, 21a ... Light emitting diode, 21b ... Photodiode, 22 ... Display device, 23 ... Mode setting unit, 24 ... Anti-vibration device,
25 ... Mechanical shake detection unit, SW1 ... First release switch, SW2 ... Second release switch.

Claims (1)

[Claims] 1. An image blur detecting means for detecting image blur, an object image moving speed detecting means for detecting moving speed of an object image based on an output of the image blur detecting means, and an object moving speed based on the object image moving speed. Correction drive amount calculation means for calculating the correction drive amount necessary to prevent image blurring, drive amount limit value output means for outputting the drive limit value of the above-mentioned correction drive amount, and the photometric value of the brightness of the subject. A camera shake preventing device, comprising: a photometering unit for outputting the exposure amount; and an exposure time calculating unit for calculating an exposure time based on the correction drive amount, the drive limit value, and the photometric value.