JPH0980551A - Image blurring correcting camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the arithmetic processing by a microcomputer for performing drive control, in a camera provided with an AF device and a VR device. SOLUTION: This image blurring correcting camera is provided with a photographing lens, the lens position detecting device 6 for detecting the arranging position in the optical axis direction, the image blurring detecting device 2, and the image blurring correcting drive control device 1 capable of controlling the drive of the image blurring correcting device by applying a specific constant number and detecting output of the image blurring detecting device 2 in the preparation photographing, and controlling the drive of the image blurring device by applying the detection output of the lens position detecting device 6 and the detection output of the detecting device in the photographing.

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 camera capable of correcting image blur caused by a blur generated in a camera.

[0002]

2. Description of the Related Art In order to correct image blur of a photographed image caused by camera shake (for example, camera shake by the photographer) at the time of shooting, correction is made according to the situation of the camera shake, the shooting magnification, etc. An accurate image blur correction amount that should be calculated must be calculated.

As an invention capable of accurately calculating the amount of image blurring to be corrected, for example, Japanese Patent Laid-Open No. 62-4701.
There is an anti-vibration optical device proposed by Japanese Patent Laid-Open Publication No. HEI 2-2. JP 6
In the invention proposed by Japanese Patent Laid-Open No. 2-47012, the lateral magnification β at the time of shooting is calculated based on the output signal from the focus position detection unit of the lens, and the converted value of the image blur amount with respect to the posture change of the camera is obtained in advance. The image blur correction amount is calculated using this conversion value and the camera posture change amount obtained from the output signal of the acceleration sensor.

[0004]

However, such conventional inventions have the following problems. Usually, in a series of shooting preparation operations started by half-pressing the release switch of the camera, the AF camera drives the shooting lens to be in focus.

At this time, the focus position of the lens may suddenly change due to the focusing drive. Further, in the so-called continuous AF mode in which the focus drive is continuously performed while the release switch is half pressed, the focus position of the lens may continuously and irregularly change as the subject moves.

When the focus position of the lens is detected continuously or stepwise, the control amount of the image blur correction drive changes stepwise, so that the photographer can observe the subject through the viewfinder during the preparation for photographing. May give an unnatural impression.

If the detection of the focus position of the lens fails, a more drastic change in the control amount may appear. Normally, the amount of image blur is calculated digitally by using a computing unit such as a microcomputer, but when the focus position of the lens changes, the focus position of the lens is detected one by one,
The repeated calculation of the image blur amount for image blur correction imposes an excessive burden on the computing capability of the computing means such as a microcomputer.

[0008]

According to the present invention, the focus position of the lens is adjusted during the preparation for photographing instead of performing the calculation of the image blur amount for the image blur correction similarly during the preparation for photographing and the time for photographing as in the prior art. It is based on the new finding that any of the above-mentioned problems can be solved by simplifying the calculation by using a fixed value for a value that changes according to the above.

According to a first aspect of the present invention, there is provided a photographing lens provided in a camera, a lens position detecting device for detecting the arrangement position of the photographing lens in the optical axis direction, and an image blur detecting device for detecting vibration applied to the camera. An image blur correction device that corrects the image blur caused by the shake of the camera; and during the preparation for shooting, driving the image blur correction device using a predetermined constant and the detection output of the image blur detection device. An image blur correction drive control device for controlling the drive of the image blur correction device by using the detection output of the lens position detection device and the detection output of the blur detection device during shooting. It is an image stabilization camera.

According to a second aspect of the present invention, in the image blur correction camera according to the first aspect, the lens position detecting device detects a rotational position of a focus ring for adjusting a position of the focus lens group in the optical axis direction. Thus, the arrangement position is detected.

[0011] The invention of claim 3 is claim 1 or claim 2.
In the image blur correction camera described in, the lens position detecting device detects the arrangement position by detecting a rotational position of a zoom ring that adjusts the position of the zoom lens group in the optical axis direction. .

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory view schematically showing the structure of the image blur correction camera used in this embodiment, and FIG. 2 is a block diagram showing the control system of the image blur correction camera.
As shown in FIGS. 1 and 2, the image blur correction camera according to this embodiment includes a lens 12 and a body 13.

A lens controller 1 is installed inside the lens barrel of the lens 12. The lens control unit 1 drives and controls various actuators (focusing control actuator, blur correction control actuator, etc.) 1 provided in the lens barrel, and is configured by a micro computer unit (MCU) or the like. .

Further, inside the lens barrel portion of the lens 12, the blur detection unit 2 is installed. The blur detection unit 2 detects blurring of the camera caused by camera shake or the like, and sends a detection output (blurring information) to the lens control unit 1 as an electric signal. A blur sensor is generally used as the blur detection unit 2, and a known piezoelectric vibration gyro or the like can be exemplified.

An image blur correction driving unit 3 is installed inside the lens barrel. The image blur correction driving unit 3 drives a mechanism that two-dimensionally shifts and drives a part of an internal-focus type photographing optical system (for example, a lens frame holding a blur correction lens) in a plane orthogonal to the optical axis C. By doing so, the image blur is corrected. The image blur correction drive unit 3 is drive-controlled by the lens control unit 1.

In FIG. 1, BX is used to shift the lens in two dimensions (the BX direction parallel to the horizontal direction and the BY direction parallel to the vertical direction) in a plane orthogonal to the optical axis C.
The actuator 3 for directions and the actuator 3 for BY directions are shown. The actuator type is not limited in any way. For example, the lens frame may be directly driven by a coil or a two-dimensional moving ultrasonic actuator combined with a magnet, or a combination of a DC motor and a screw or a cam may be used.

An image blur correction mode changeover switch 4 is provided on the outer surface of the lens barrel. The image blur correction mode changeover switch 4 is connected to the lens control unit 1, and an "ON mode" in which the image blur correction drive unit 3 is in a drivable state during shooting preparation or during shooting, and a "non-driving state". This is a switch for switching between "OFF mode". Considering the convenience during operation, it is desirable to use a state holding switch such as a slide switch.

Inside the lens barrel, a lens drive unit 5 for driving the focus of the photographing optical system is provided. A DC motor, an ultrasonic motor, or the like is used as the lens driving unit 5, and the lens control unit 1 controls the driving.

A lens drive position detector 6 is provided inside the lens barrel. The lens drive position detection unit 6 detects the lens position of the lens in the focusing optical system that is driven in focus by the rotational position of the cam ring 11 described later, and sends the detection output to the lens control unit 1.

An example of the lens drive position detector 6 is schematically shown in FIG. As shown in FIG. 3, a conductive brush 11a fixed to a cam ring 11 to be described later and integrally moving, and a gray code pattern printed board 1 fixed to the lens barrel side, for example.
1b, it is preferable to use an absolute encoder type capable of detecting the absolute rotational position of the cam ring 11. The gray code pattern printed board 11b is connected to the lens controller 1.

It should be noted that a detection signal from the lens drive position detector 6 may be transmitted to the lens controller 1 for drive control of the lens driver 5, but a separate incremental encoder for drive control of the lens driver 5 is used. The type detection unit may be further provided directly on the lens drive position detection unit 6 or the lens drive unit 5.

Further, the lens drive position detector 6 may be constituted by a combination of a predetermined absolute position detection and a relative position detection from the absolute position detection, that is, a combination of an absolute encoder and an incremental encoder.

An image blur correction start switch 7 is provided on the outer surface of the lens barrel. When the image blur correction mode changeover switch 4 is in the "on mode" and the release half-press switch 9a described later is "on", when the image blur correction start switch 7 is turned "on", the lens control unit 1 The shake correction drive control is started.
When the image blur correction start switch 7 is turned off, the image blur correction drive control is stopped.

The image blur correction start switch 7 may be turned on only when it is desired to perform image blur correction. Considering the convenience at the time of photographing, the switch 7 is "on" only while the switch is being pushed and is automatically "off" when the switch is released. A momentary switch that is "off" is preferred.

A body control section 8 is provided inside the body 13. The body control unit 8 is composed of a micro computer unit (MCU) or the like, and performs actuator drive control, focus position detection, exposure calculation, and the like in the body 13 (not shown), and a lens control unit via an electrical contact or the like. 1 and communicates with 1 to control the operation of the entire camera. The body control unit 8 communicates with the lens control unit 1 to control the operation of the entire camera.

A release switch 9 is provided on the outer surface of the body 13. The release switch 9 is connected to the body control unit 8 and has a half-push switch 9a for starting the photographing preparation operation and a full-push switch 9b for starting the photographing operation.

Inside the body 13, there is provided a power supply unit 10 for supplying power to the actuators and control unit of the entire camera. In the present embodiment, the power supply unit 10 is of one type, but may be separately configured, for example, an image blur correction driving power supply unit and a power supply unit for other mechanisms.

A cam ring 11 is provided inside the lens barrel. The cam ring 11 is rotationally driven by the lens driving unit 5 and is used to change the position of the focusing lens of the photographing optical system. It may also be rotated by the distance ring operation by the photographer. This cam ring 1
The rotational position of 1 is detected by the lens drive position detection unit 6 as described above.

FIG. 4 is an explanatory diagram showing the flow of control in this embodiment. In step (hereinafter abbreviated as "S") 100, the half press switch 9a of the release switch 9 is pressed, whereby the body control unit 8 causes the camera to start a series of shooting preparation operations, and
Similarly, the lens control unit 1 also starts the shooting preparation operation operation, starts the operation mode selection, and proceeds to S110.

In step S110, the lens controller 1 detects the state of the image blur correction mode changeover switch 4 and determines whether or not it is in the "on mode". "On mode"
If not, skip S120 to S140 that follow.
The process proceeds to focusing drive of 150, and if it is the "on mode", the process proceeds to S120.

In step S120, the lens controller 1 detects the state of the image blur correction start switch 7 and determines whether it is in the "on mode". If it is not in the "on mode", skip the subsequent S130 and S140 and proceed to S15.
If the focus control is 0, and if the mode is "on mode", S
Proceed to 130.

In S130, in order to control the image blur correction drive, the lens controller 1 substitutes a predetermined constant as a substitute for an image blur drive parameter (described later) obtained from the detection output of the lens drive position detector 6. E ′ (described later) is read from the storage unit. Here, a control method of the image blur correction drive will be briefly described.

FIG. 5 is an explanatory diagram showing the relationship between camera shake (angle change of the optical axis) and image shake of the subject image in the present embodiment. The object O and the front main surface H of the imaging optical system
Is a, and the distance between the rear principal surface H ′ of the photographing optical system and the image forming point I is b. The image formation point I is
Specifically, it means on the surface of the photographic film and is always at a fixed position with respect to the camera.

Further, the distance between the front principal surface H and the rear principal surface H'of the photographing optical system (that is, the optical lens thickness) is represented by = T.
And Further, if the distance between the imaged object O and the image formation point I is R,

[0036]

[Equation 1]

The change in the angle of the optical axis means that the camera is blurred so as to rotate the optical axis around a certain point on the optical axis. Therefore, this rotation center is set to the point N and is connected to the point N. The distance to the image point I is n.

As shown in FIG. 6, it is assumed that the optical axis of the camera device is inclined by θ around the point N. Letting φ be the change in the incident angle of the subject light to the photographing optical system (0 before tilting), the following values are obtained.

[0039]

[Equation 2]

Therefore, the image blur amount D has the following value due to the image formation relationship.

[0041]

(Equation 3)

The relationship between the shift movement amount of a part of the lens (referred to as correction optical system) of the photographing optical system which is shift-driven by the image blur correction driving unit 3 and the image movement caused by the shift movement is 1: 1, that is, d in FIG.
In order to correct the image blur amount D when s = di,
The correction optical system may be shifted in the opposite direction by the same amount. That is, if the correction optical system shift drive amount at the optical axis inclination θ is ds (θ), the following values are obtained.

[0043]

(Equation 4)

Here, in general, ds = di × C (C =
Coefficient), the formula is as follows.

[0045]

(Equation 5)

In the above equation, (C × b × (R−
n) / a) is referred to as image blur correction drive parameter = E. The image blur correction drive parameter is a proportional coefficient between the amount of change in the angle of the camera optical axis and the image blur correction amount.

In the above equations and equations, n is usually 0 (rotation center = film surface) and a suitable value in the distance from the center of gravity of the entire camera may be empirically determined and set. .

Further, in the above equations and equations', θ can be easily obtained based on the detection output of the blur detection unit 2.
For example, if the shake detection unit 2 is a vibration gyro, the angular velocity detection output can be integrated for each unit time to obtain the angle dimension.

Further, in the above equations and equations', FIG.
In the internal focus type lens as in the present embodiment shown in FIG. 2, the focal length f and the lens thickness T slightly change depending on the shooting distance R,
Although the relationship between a, b, and R changes slightly, ds (θ)
Has a large effect on the value of ((R-n) /
It is a change in the value of a).

Therefore, from the form of the equation, if n = 0, "{(R-n) / a} = 1" at a long distance.
Is substantially valid, and when the distance is short, “{(R-n) / a}
The degree of> 1 ”becomes stronger.

That is, with respect to the same camera shake angle, there is a tendency that the image shake amount becomes larger at a short distance. Therefore, if the rotational position of the cam ring 11 is sequentially detected by the lens drive position detector 6, for example, the photographing distance R
Can be detected and the equation can be solved each time, or several image blur correction drive parameters E can be stored in advance in accordance with the shooting distance R. However, the image blur correction drive parameter changes very often,
If the lens drive position detector 6 makes an erroneous detection, there is a possibility that the image blur correction drive parameter may be incorrect.

Further, this series of detection / storage / readout processing may give an excessive calculation load to the lens controller 1 which also needs to control focusing drive. On the other hand, during the preparation for photographing, even if the accuracy of the image blur correction is deteriorated to some extent, there is no problem as long as it does not hinder the finder observation of the photographer.

Therefore, a predetermined constant E'representing the image blur correction driving parameter in the expression 'is set, and the correction optical system shift driving amount can be simply expressed by the following expression.

[0054]

(Equation 6)

However, E'is a constant. By doing so, the image blur correction drive amount to be calculated by the lens control unit 1 has a simple relationship with respect to the output of the shake detection unit 2, so that the behavior of the image blur correction drive is stabilized, and the calculation by the lens control unit 1 is performed. The load is also very small.

Therefore, in S130, in order to control the image blur correction drive, the lens controller 1 does not use the detection output of the lens drive position detector 6, but uses E of the above formula 'as the image blur correction drive parameter. The predetermined constant that is represented is read from the storage unit.

Here, as the value of the constant E ', it is preferable to use "C.times.bj.times. (Rj-n) / aj" at the usual photographing distance "Rj". However, depending on the type of lens, if the usual shooting distance is set to a relatively short distance (large magnification shooting), the degree of "{(R-n) / a}>1" will be strong, If you set the value of E'as a constant,
Image blur correction driving at a long distance may be overcorrected.

In such an overcorrected state, the image blur observed in the viewfinder is generated in the direction opposite to the direction of the image blur originally observed, which gives an unnatural impression to the photographer. give.

In order to avoid this, the setting of the constant E'may be made small within the allowable range depending on the lens type. For example, a constant E ′ = C × b∞ (b∞: value of b at infinity) ”may be used.

Further, by using the constant E'in this way, it is possible to prevent the inconvenience that the control amount of the image blur correction drive changes stepwise even if the focus position of the lens changes abruptly. Even if the focus position detection fails, the risk of a drastic change in the control amount can be avoided.

In S140, the lens control section 1 determines S1
The value of the constant E'set in 30, and the blur detection unit 2
The image blur correction drive amount is calculated based on the detection output of
The drive control of the image blur correction drive unit 3 is performed. If an image blur correction drive program (shooting preparation mode) is being prepared during shooting preparation, such as by adding a centering bias that controls the camera shake correction mechanism to constantly return to the center side during non-shooting Take control.

In S150, the lens control section 1 controls the drive of the lens drive section 5 based on the focus detection information from the body control section 8 and the like to focus the photographing optical system.
In S160, the body control unit 8 determines whether or not the full-press switch 9b is on, and if it is on, S
If not “ON”, the process returns to S110.

Since the full-push switch 9b is not turned on, when returning to S110 and repeating S110 to S160, steps such as S130 that may be performed once may be omitted.

In S170, the lens control unit 1 calculates the accurate image blur correction drive parameter E by calculation as shown in the expression ', based on the lens position detection output from the lens drive position detection unit 6. Alternatively, the stored value is read.

Unlike the contents of S140, the setting of the image blur correction drive parameter performed in S170 does not use the substitute value E'of the detection output of the lens drive position detection unit 6, but the image accurately derived from the expression '. The shake correction drive amount is used. S
This is because if the film is 170 or less, the film is exposed, and therefore accurate image blur correction driving must be performed.

In the shooting operation from S170 onward, the focusing drive of the normal lens is completed, and the focus position of the lens is unlikely to change abruptly. Is also low.

S180: The lens control section 1 calculates the image blur correction drive amount based on the image blur correction drive parameter of the exact solution set in S170 and the detection output of the shake detection section 2, and the image blur correction drive section is calculated. 3 drive control is performed.
When an image blur correction driving program (during-photographing mode) during shooting is prepared depending on how to apply the centering bias, etc., the drive control is performed.

It should be noted that once the drive position of the image blur correction drive unit 3 is returned to the neutral point at the start of driving, it is effective in securing the image blur correction stroke during exposure. The control may be the same as the control in the shooting preparation mode. Further, the reset to the neutral point may not be performed if it is not necessary.

In S190, the body control section 8 controls a shutter drive section (not shown) to start exposure of the film. In S200, the body control unit 8 terminates a series of exposure operations of the camera after a predetermined time. Timing is set by communication from the body control unit 8, and the lens control unit 1
Starts the operation after the end of the exposure operation.

If the drive control method of the image-recording correction program (shooting mode) to the image-blur correction drive unit 3 is to temporarily stop the image-blur correction drive after the exposure is completed, the image-blur correction drive is temporarily stopped. At this time, returning the drive position of the image blur correction drive unit 3 to the neutral point is effective in securing a correction stroke when restarting the image blur correction drive.

In the present embodiment, as shown in FIG. 4, after the image blur correction drive is started in S140, S
Although the focusing drive is started at 150, the order is not limited to this order. The focusing drive may be started before the image blur correction drive is started. For example, when the focus drive is continuously performed, it does not matter which order comes first.

As described above in detail, according to the present embodiment, the focus position of the lens for calculating the image blur correction amount is set during the shooting preparation in which the state of the image blur correction drive is directly observed by the finder. Since a fixed substitute value is used for the value that changes accordingly, it is possible to prevent the control amount of the image blur correction drive from changing stepwise or abruptly, and obtain a natural viewfinder observation image. .

Further, according to the present embodiment, it is possible to simplify the arithmetic processing in the microcomputer that performs drive control, prevent an excessive arithmetic load on the lens control section, and reduce the size of the microcomputer.
Low power consumption can be achieved.

Further, according to the present embodiment, by simplifying the arithmetic processing, the arithmetic processing for the focusing drive control of the lens, the image blur correction drive control and the like can be centralized, and more Fine control can be performed.

Strictly speaking, since the focus position information is a substitute value, the image blur correction amount may have an error, but this is during preparation for photographing, and in the present embodiment, it is actually performed. The image blur correction drive is controlled based on accurate focus position information (usually, the focus position does not change during exposure because the lens is in focus during exposure) during shooting when the film is exposed. Because
It has no adverse effect on the shooting result.

(Second Embodiment) Next, a second embodiment of the present invention will be described. In the following description of each embodiment,
Only the parts different from the first embodiment will be described, and the same parts will be denoted by the same reference numerals in the drawings to omit redundant description.

FIG. 6 is an explanatory diagram showing the flow of control in the second embodiment. That is, in the control flow of the first embodiment shown in FIG. 4 described above, when the image blur correction start switch 7 (S120) is omitted and the image blur correction mode changeover switch is ON, the release half-push switch 9a. By turning on, the image blur correction drive is automatically started.

The difference from the control flow shown in FIG.
Since it has only been omitted, further explanation is omitted.

(Third Embodiment) FIG. 7 shows a modification of the image blur correction camera according to the present invention provided with a zoom lens.

The parts added to the parts shown in FIG. 1 will be described, and the same parts will be denoted by the same reference numerals in the drawing and the description thereof will be omitted. In the present embodiment, the zoom position detector 14 is provided inside the lens barrel. The zoom position detection unit 14 detects the position of the zoom lens group in the photographing optical system based on the rotational position of the zoom ring 15, which will be described later, and sends the detection output to the lens control unit 1.

The zoom position detecting section 14 is, similarly to the lens driving position detecting section 6 in FIG. 1, a conductive brush fixed to the zoom ring 15 to move integrally, and a gray code pattern fixed to the lens barrel side. An absolute encoder type constituted by a printed board is suitable.

Further, a zoom ring 15 is provided inside the lens barrel. The zoom ring 15 is rotated by a zoom operation ring provided on the outer surface of the lens barrel to change the position of the zoom lens group in the photographing optical system. The rotational position of the zoom ring 15 is detected by the zoom position detection unit 14 described above.

Similar to the image blur correction cameras described in the first and second embodiments, in this embodiment in which the focal length of the photographing optical system can be adjusted, the image blur set in S130 described in the flowchart of FIG. 4 is set. It is desirable to set the correction drive constant parameter E'as a small value. This is to prevent the camera shake correction drive from being overcorrected.

Therefore, in the case of an image blur correction camera having a zoom lens, it is preferable that the value of the image blur correction drive constant parameter E'described above is as small as possible within the range suitable for the photographing situation.

For example, if the shortest focal length that the zoom lens can take is fwi, the image blur correction driving constant parameter E ′ = C × fwi may be set. In addition, S in FIG.
The accurate calculation or reading of the image blur correction drive parameter E performed at 170 is performed based on the detection outputs of the lens drive position detection unit 6 and the zoom position detection unit 14.

[Brief description of drawings]

FIG. 1 is an explanatory diagram schematically showing the structure of an image blur correction camera according to a first embodiment.

FIG. 2 is a block diagram showing a control system of the image blur correction camera of the first embodiment.

FIG. 3 is an explanatory diagram schematically showing an example of a lens drive position detector 6.

FIG. 4 is an explanatory diagram showing a control flow in the first embodiment.

FIG. 5 is an explanatory diagram showing a relationship between camera shake (angle change of optical axis) and image shake of a subject image in the first embodiment.

FIG. 6 is an explanatory diagram showing a control flow in the second embodiment.

FIG. 7 is a modification of the image blur correction camera according to the present invention including a zoom lens, and shows an image blur correction camera according to a third embodiment.

[Explanation of symbols]

 1 Lens Control Section 2 Blur Detection Section 3 Image Blur Correction Drive Section 4 Image Blur Correction Mode Changeover Switch 5 Lens Drive Section 6 Lens Drive Position Detection Section 7 Image Blur Correction Start Switch 8 Body Control Section 9 Release Switch 10 Power Supply Section 11 Cam Ring 11a brush 12 lens 13 body 14 zoom position detector 15 zoom ring

Claims (3)

[Claims] 1. A photographing lens provided in a camera, a lens position detecting device for detecting an arrangement position of the photographing lens in an optical axis direction, an image blur detecting device for detecting vibration applied to the camera, and a camera An image blur correction device that corrects an image blur caused by a shake, and during the preparation for shooting, while controlling the drive of the image blur correction device using a predetermined constant and the detection output of the image blur detection device, And an image blur correction drive control device for controlling the drive of the image blur correction device using the detection output of the lens position detection device and the detection output of the blur detection device. camera. 2. The image blur correction camera according to claim 1, wherein the lens position detection device detects the rotational position of a focus ring that adjusts the position of the focus lens group in the optical axis direction, thereby performing the arrangement. An image blur correction camera characterized by detecting a position. 3. The image blur correction camera according to claim 1, wherein the lens position detection device detects a rotational position of a zoom ring that adjusts the position of the zoom lens group in the optical axis direction. An image blur correction camera characterized in that the arrangement position is detected by means of.