JP3531642B2 - Interchangeable lens with image stabilization function - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens-interchangeable image pickup apparatus such as a camera, and more particularly, to an image shake suitable for application to a lens-interchangeable image pickup apparatus capable of correcting image shake during photographing.
An interchangeable lens with a correction function .

[0002]

2. Description of the Related Art In a photographing apparatus represented by a camera,
As an image blur correction photographing device that detects an angular variation of an optical axis due to camera shake or the like and corrects a photographed image by this, for example, Japanese Patent Application Laid-Open Nos. 2-66535 and 2-183217.
The one shown in Japanese Patent Publication has been conventionally known.

Here, the former camera capable of image blur correction is an example in which the photographing optical system is a single lens optical system, and a blur detecting means for detecting image blur and this detecting means are used. Drive means for driving a single-lens lens optical system, which is a shake correction optical system, to perform shake correction according to the above signal, thereby preventing image shake due to camera shake or the like. The former camera is provided with a restraint means such as an electromagnetic braking device, and the shake prevention optical system is free during photographing, while the non-shooting optical system is held in a restrained state. Has been taken.

In the latter lens barrel capable of correcting image blur, the angular accelerometer as a shake detecting means is set at a desired position which becomes a center of gravity when coupled with the camera body in a photographing optical system using an internal focusing type telephoto lens. This is an example in which image blur is prevented by mounting the image pickup device and shifting a part of the photographing optical system in accordance with the shift by the shake correction driving means.

[0005]

By the way, in the above-mentioned photographing apparatus, an internal focusing lens is mainly used as a telephoto lens of a camera which most requires an image blur correction technique.

However, the focal length (f) of such an in-focus type lens gradually changes from infinity shooting to close-up shooting.

Therefore, in the telephoto lens using such an in-focus type lens, the correction amount can be obtained only by the image shake correction drive control by the simple image shake amount calculation method as disclosed in the former conventional example described above. Error.

Further, in such a telephoto lens, the optical lens thickness (distance between principal planes H) in the photographing optical system is used.
H ′) also changes, the distance “a” between the taking lens and the subject and the distance “b” between the taking lens and the film surface in the above-described conventional example are simply obtained only from the subject taking distance. I can't.

The problems associated with these changes in focal length and lens thickness occur not only in the telephoto lens but also in the zoom lens.

Further, in these photographing devices, by identifying the rotation center position on the optical axis of the device, image blurring due to rotation in such a photographing device is eliminated, and the above-mentioned rotation center position and photographing lens incidence part. It is possible to eliminate the influence caused by the movement of the and to more accurately calculate the image blur amount.

However, in a photographing device such as a lens-interchangeable camera, the rotation center position of the photographing device on the optical axis changes depending on the combination of the lens barrel and the camera body. Therefore, such a lens-interchangeable image pickup device cannot accurately calculate the amount of image blur, and it is necessary to take some measures capable of solving such a problem.

The present invention has been made in view of the above circumstances, and in a conventional interchangeable lens with an image blur correction function having a detection means for detecting an angular variation, which one of a camera body and a lens barrel is used? The object of the present invention is to obtain an interchangeable lens with an image blur correction function that enables more accurate image blur correction even when combined as described above.

[0013]

In order to meet such a demand, an interchangeable lens with an image blur correction function according to a first aspect of the present invention comprises an internal focusing optical system for taking an image and one of the internal focusing optical system.
Image blur correction drive unit for relatively shifting the elements of the internal focus optical system and a screen imaged by the internal focus optical system for image blur correction, and a rear main plane of the internal focus optical system to an image forming point. A calculation means for calculating a distance between them, an angle change detection means for detecting a rotational shake due to a hand shake with respect to the internal focus optical system, a communication means for communicating information on the image shake correction with the camera body, and a communication means for obtaining the information. the rotation center determining means for determining a rotational center of the image blur based on the obtained information, and information from the calculation means, and information from the angle change detecting means, on the basis of the information from the rotation center determining means An image blur correction drive control unit for driving and controlling the image blur correction drive unit is provided.

A second invention is the same as the first invention,
Further comprising a focus position information detection unit for detecting focus position information of the internal focus optical system , the image blur correction drive control unit, the information from the focus position information detection unit, the information from the calculation unit, The drive control of the image blur correction drive unit is performed based on the information from the angle change detection unit and the information from the rotation center determination unit. In a third aspect based on the first or second aspect, the center of rotation is obtained based on the weight and center of gravity of the interchangeable lens and the weight and center of gravity of a camera body combined with the interchangeable lens. Further, in a fourth aspect based on the first, second or third aspect, the image blur correction drive control section further includes a photographing distance (R) and a distance between the photographing object and the front main plane of the photographing optical system. The image blur correction drive unit is drive-controlled based on the distance (a).

According to the present invention, each characteristic value (focal length:
f (= f '), optical lens thickness: T, principal plane H'on lens rear side-distance between image planes: b, etc.) is used to calculate the image shake amount, and the camera body is further calculated. And to determine the center of rotation based on the center of gravity and weight unique to the lens barrel, no matter how the combined posture of the lens barrel and camera body changes, the correct center of rotation position is calculated each time. Therefore, the image blur amount can be accurately calculated, and the image blur correction optical system can be driven and controlled by the control unit and the drive unit in a required state to perform the image blur correction.

According to the present invention, the weight and the center of gravity of the camera body and the interchangeable lens barrel are combined.
By configuring so as to determine the rotation center of the image shake based on this, it is possible to calculate and determine the accurate rotation center position regardless of how the lens barrel and the camera body are combined, and to calculate the accurate image shake amount. Then, the image blur correction optical system is driven and controlled in a required state by the control unit and the drive unit to perform image blur correction.

[0017]

1 to 4 are images according to the present invention.
1 shows an embodiment of an interchangeable lens with a shake correction function . In these figures, first, a schematic configuration of an entire lens interchangeable camera to which the present invention is applied by using FIG. 1 will be described below. To do.

That is, in FIG. 1, reference numeral 1 is a camera body, and a camera side CPU 2 by a one-chip microcomputer (hereinafter referred to as a first MCU) is provided in the camera body 1 to communicate with a lens barrel 3. It is configured to perform various drive controls of the camera such as release, exposure and film winding.

Reference numeral 4 denotes a lens barrel side CPU provided by a one-chip microcomputer (hereinafter referred to as a second MCU) provided in the lens barrel 3, and various lenses such as communication with the camera body 1 and image blur correction. It is configured to perform drive control.

Reference numeral 5 is an angle change detection provided on the lens barrel 3 side.
The angular velocity detection unit as the output unit detects rotational shake that causes image shake such as camera shake as the angular velocity. In addition, as the angular velocity detection unit 5,
A known vibration gyro angular velocity meter may be used.

Reference numeral 6 denotes an image blur correction drive unit for shifting and driving the image blur correction optical system, which constitutes a part of the photographing optical system arranged in the lens barrel 3, in a required state. Is provided with a monitor unit that detects the shift amount of the above and sends it to the second MCU 4 as a monitor signal.

Reference numeral 7 denotes a focus position detection unit for detecting the position of the focus adjustment optical system in the photographing optical system, which is constituted by sensor means such as an encoder for reading the rotational position of the focus / cam ring, and the focus of the photographing optical system. Detect the condition.

Reference numeral 8 in the drawing denotes an electrical contact, which is electrically connected when the camera body 1 and the lens barrel 3 are combined to enable communication between the camera body 1 and the lens barrel 3.

The structure of each part of the camera body 1 and the lens barrel 3 other than those described above is well known in the art, and a detailed description thereof will be omitted.

FIG. 2 is a block diagram of a control circuit in the camera body 1 and the lens barrel 3 shown in FIG. 1 described above. Here, the electrical contact 8 is configured as follows in order to perform clock synchronous communication.

That is, reference numerals 8a and 8A in the drawing denote clock terminals (SCLK, SCLK) for outputting a clock from the body 1 side. 8b is the lens barrel 3
Side data output terminal (SOUT), 8B is a body 1 side data input terminal (SIN), and 8c is a lens barrel 3
Side data input terminal (SIN) and 8C are body 1 side data output terminals (SOUT). 8d and 8 in the figure
D is a ground terminal (GND, GND).

FIG. 3 is a block diagram of an image blur correction function according to the present invention.
FIG. 6 is an explanatory diagram for explaining a relationship between shake (angle change of optical axis) and image shake of a subject image in a camera including a replacement lens .

Here, a in the figure is a photographing object to a photographing optical system.
The distance between the principal planes (H) on the front side of the lens, b is the photographic optical system
It is the distance between the principal plane (H ') on the rear side of the lens and the image plane.
The “imaging plane” is specifically the plane of the photographic film and is always a fixed position with respect to the camera body 1.

Further, T in the drawing is a distance between the main plane (H) on the front side of the lens and the main plane (H ') on the rear side of the lens, which is the above-mentioned optical lens thickness.

In the figure, R is the distance between the object to be imaged and the image plane, and this R is R = a + T + b (Equation 1).

Further, "angle change of optical axis" means that the entire camera (photographing apparatus) is swung so as to rotate the optical axis around a certain point on the optical axis of the photographing optical system. The center of rotation is the point N, and the distance between this point N and the image plane is
In the figure, n.

Further, as shown in FIG. 3, it is assumed that the optical axis of the entire camera changes around the point N by dθ within a certain minute time (= dt) with respect to the stationary subject.

In other words, it can be regarded that the direction of the subject has changed (−dθ) with respect to the device of the present invention with the point N as the center. In FIG. 3, the movement equivalent amount of the subject due to this change is indicated by Do.

Then, when the amount of change in the incident angle of the subject light on the photographing optical system is (-dφ), the following values are obtained. −dφ = (a + T + b−n) × (−dθ) / a = −dθ × (R−n) / a (Equation 2)

Therefore, the image blur amount (shown as Dim in FIG. 3) has the following value due to the image formation relationship. Dim = b × (−dφ) = − b × dθ × (R−n) / a (Equation 3)

In the present embodiment, assuming that the relationship between the shift amount of the correction optical system and the image movement is ds = di, in order to correct the image shake amount Dim described above, the correction optical system is moved in the reverse direction. It will be enough to shift by the same amount.

That is, if the shift drive amount of the correction optical system at the optical axis change amount dθ is ds (dθ), the following values are obtained. ds (dθ) = − Dim = b × dθ × (R−n) / a (Equation 4)

Generally, since ds = di × C, the following is obtained. ds (dθ) = C × b × dθ × (R−n) / a (C: constant) (Equation 5)

When the position of the shake correction optical system is not already at the center position (when the image shake correction drive is being continued)
3 and the above-mentioned (Equation 1) to (Equation 5)
The same image blur correction drive as that described in 1) may be performed.

Further, the shift position of the correction optical system at the start of the image blur correction driving (t1) is S
Speaking of (t1), the shift position S (t1 + dt) of the correction optical system after dt time has the following relationship.

[0041]     S (t1 + dt) = S (t1) + ds (dθ)                     = S (t1) + {C × b × dθ × (R−n) / a}                                                         ... (Equation 6)

Then, the above (formula 4) and (formula 5)
In the internal focus type lens as in the present embodiment,
The focal length f (= f ′) and the lens thickness “T” change depending on the shooting distance “R”.

Here, in the case of a normal all-group extension type lens, since the values of the focal length “f (= f ′)” and the lens thickness “T” do not change, only this numerical information is previously stored in the second MCU.
If the shooting distance "R" can be detected (for example, the rotational position of the lens distance ring is detected), the above "a" and "b" can be stored by a simple calculation (Newton's imaging formula). Desired.

However, in the above-mentioned internal focus type lens, the values of the focal length "f (= f ')" and the lens thickness "T" change depending on the photographing distance "R", so that the focal length "f"
(= F ′) ”and the value of the lens thickness“ T ”are stored only, it is impossible to accurately calculate the image blur amount.

By the way, in the internal focusing lens (of a kind called a single focus internal focusing lens), if the shooting distance "R" is determined, the focal length "f (= f ')" in the shooting state,
By determining the lens thickness "T" and the focal length "f (= f ')", "b" is uniquely determined.

Therefore, if the rotational position of the lens distance ring is detected and the accurate values of "T" and "b" corresponding to the detection result can be used for the sequential calculation, the above-mentioned expression (Equation 4) is obtained each time. Since the variables “b”, “R”, and “a” used for are determined, it is possible to accurately calculate the image blur amount.

The focus position detector 7 described with reference to FIG. 1 is installed for this purpose, and outputs the rotational position information of the focus cam ring to the second MCU 4. Further, the second MCU 4 stores a correspondence table of the focus position and the values of “b”, “R”, and “a” described above, and can be used for calculation of the image shake amount.

Next, the determination of the other variable term "n" of (Equation 4) described above will be described below.

That is, with respect to the above-described shake of the photographing apparatus, hand shake can be considered. It is experimentally confirmed that the rotation center of the shake at this time is different when the total weight of the camera body 1 and the lens barrel 2 is large and when it is large.

In the former case, the camera body 1
However, since the camera body 1 is in contact with the photographer's face at the eyepiece portion, the rear end portion of the camera body 1 is not largely displaced. Therefore, the rotational shake of the image pickup apparatus is centered around the body eyepiece portion. Rotational runout easily occurs.

In the latter case, since the weight is large,
The center of rotation often occurs at the center of gravity including the camera body 1 and the lens barrel 2.

Therefore, if the positions of the weight and the center of gravity of the camera body 1 and the lens barrel 2 can be discriminated, the position of the center of rotation of the optical axis of the photographing apparatus can be specified.

When the weight of the camera body 1 is Wc, the center of gravity from the film surface is Lc, the weight of the lens barrel 2 is Wl, and the center of gravity from the film surface is Ll,
The relationship between the camera body 1 and the overall center-of-gravity position Lt of the lens barrel 2 is expressed by the following (Equation 7).

That is,     (L1−Lt) × Wl = (Lt−Lc) × Wc (Equation 7) It is represented by.

From this (Equation 7), the total center of gravity position Lt is Lt = (Ll × Wl + Lc × Wc) / (Wc + Wl) (Equation 8).

When the total weight (Wc + Wl) of the camera body 1 and the lens barrel 2 is small, n = 0 because the center of rotation is close to the eyepiece, and (Wc + Wl)
When Wl) is large, n = L by setting the total center of gravity of the camera body 1 and the lens barrel 2 as the center of rotation.
t.

Finally, the variable term "d" of the above (formula 4)
The determination of “θ” will be described.

First, the second MCU 4 detects the angular velocity signal output from the angular velocity detector 5, and the second MCU 4 detects the angular velocity signal.
The angular velocity “ω” of the rotational shake may be calculated using the conversion coefficient of the angular velocity signal strength and the angular velocity value stored in advance in FIG.

Here, the first MCU 2 which is the CPU unit portion of the camera body 1 performs the above-mentioned angular velocity signal detecting operation at every certain fixed time (every dt time).

Therefore, "dθ" may be calculated by the following calculation. dθ = ω × dt (Equation 9)

By the above, all the variables used in the above-mentioned (Equation 4) are fixed, and the shift drive amount ds (dθ) in the correction optical system at the optical axis change amount dθ can be calculated.

In the above description, the shift drive amount ds (dθ) in the correction optical system for the shake in which the change amount of the optical axis in the photographing device is dθ is calculated, but the tilt of the optical axis in the photographing device is calculated. Speed, that is, the shift drive speed of the correction optical system with respect to the angular velocity “ω” of the rotational shake (expressed as ds ′ (ω))
For the above, the same formula as the above (Formula 4) can be used.

[0063]         ds' (ω) = b × ω × (R−n) / a (Equation 10)

Then, in general, as in the case of (Equation 5), the following is obtained. ds' (ω) = C × b × ω × (R−n) / a (C: constant) (Equation 11)

FIG. 4 is a flow chart for explaining the operation sequence of the second MCU 4 relating to image blur correction in the apparatus of this embodiment shown in FIG. Here, the calculation of the image blur correction amount is based on the various expressions described with reference to FIG.

First, in step (hereinafter abbreviated as S) 200, information about the weight Wc of the camera body 1 and the center of gravity position Lc is communicated from the first MCU 2 to the second MCU 4 via the contact 8.

Then, in step S201, a position detection signal of the focus adjustment optical system is input from the focus position detection unit 7 in order to detect the current lens state.

Further, in S202, the above-mentioned S2 is performed.
Corresponding to the signal input at 01, the photographing distance "R", the distance "a" between the photographing object and the photographing optical system / lens front principal plane (H), the photographing optical system / lens rear principal plane (H ') ~ Each value of the distance "b" between the image formation points is selected from the numerical values stored in advance in the second MCU 4, and is used as the numerical value used for the calculation.

Further, in S203, the angular velocity detector 5
The angular velocity signal output by is detected, and the angular velocity “ω” of the rotational shake is calculated using the conversion coefficient of the angular velocity signal intensity and the angular velocity value stored in advance in the second MCU 4.

Further, in S204, the optical axis change amount "dθ" due to the rotational shake of the photographing device at a predetermined time is calculated. Here, the second MCU 4 performs the angular velocity signal calculation operation in S203 every certain predetermined time (every dt time).
In addition, “dθ” is calculated by dθ = ω × dt, as described in the above-described formula (Formula 11).

Next, in S205 and thereafter, the center of rotation of the shake of the photographing device is detected.

First, in S205, the weight Wc of the camera body 1 obtained in S200, the center of gravity Lc, and the weight Wl of the lens barrel 2 previously stored in the second MCU 4,
The total weight Wt (= Wc + Wl) of the camera body 1 and the lens barrel 2 and the center of gravity position Lt are obtained from the center of gravity position Ll.

Then, if the total weight Wt is larger than a predetermined value in S206, n = Lt is set (S207), and if it is smaller, n = 0 (S208).

Further, in S209, the image blur correction driving amount is calculated by using (Equation 4) described in FIG. 3 (using (Equation 5) as a general solution).

After that, the process advances to S210 to control the image blur correction drive section 6 to shift drive the image blur correction optical system.

After the above is completed, the process returns to S201, and thereafter S
The routines 201 to S210 are constantly repeated while the image blur correction drive is performed.

As is clear from the above description, according to the interchangeable lens with the image blur correction function according to the present embodiment, from the lens state to the photographing distance "R", the photographing object to the photographing optical system / lens front principal plane ( H) distance "a", in-focus type
Each value of the distance "b" between the optical system / lens rear principal plane (H ') and the image forming point is specified, and further, the distance "n" between the rotation center point N and the image forming point is specified as the case may be. By doing so, a more accurate image shake amount can be calculated from the detected rotational shake angle “dθ” of the image pickup apparatus, and image shake correction drive that can correct the image shake amount accurately becomes possible.

It is needless to say that the present invention is not limited to the above-described embodiments, and the shape, structure, etc. of each part of the interchangeable lens with an image blur correction function can be appropriately modified or changed.

For example, although only the vertical angular velocity detecting section and the image blur correction driving section are shown in FIG. 1, the apparatus of this embodiment can be similarly applied in the horizontal direction (corresponding to the vertical direction in the drawing). The truth is clear. Further, it goes without saying that such a combination of vertical and horizontal directions may be used.

[0080]

As described above, according to the interchangeable lens with the image blur correction function according to the present invention, the internal focusing type light for performing the image pickup is obtained.
Science system, some elements of the internal focusing optical system, and the internal focusing optical system
An image blur correction drive unit that relatively shifts a screen imaged by the system for image blur correction, and a distance between a rear main plane of the internal focusing optical system and an image formation point is calculated. a calculation means that, before
An angle change detection unit that detects rotational shake due to camera shake with respect to the internal focus optical system, and information regarding the image shake correction are recorded.
Communicating means for communicating with Merabodi, the rotation center determining means for determining a rotational center of the image blur based on the information obtained by the communication means, the information from the angle change detecting means and information from the calculation means, Since the image blur correction drive control unit that drives and controls the image blur correction drive unit based on the information from the rotation center determination unit is provided, the following excellent effects are achieved.

That is, according to the present invention, each characteristic value (focal length: f (= f ')) of the photographing optical system is detected by detecting the state of the photographing optical system in the photographing apparatus which changes depending on the photographing state. , An optical lens thickness: T, an accurate value of a principal plane H ′ on the rear side of the lens to a distance between imaging planes: b, etc. can be obtained, and an image shake amount can be calculated using these values, so that the shooting state It is possible to accurately calculate the image blur amount in the above condition, and it is possible to perform highly accurate image blur correction driving.

Further, according to the present invention, it can be determined in what position state these camera bodies and lens barrels are combined according to the information on the weight and center of gravity positions of the camera bodies and lens barrels that constitute the photographing apparatus. It is also possible to specify the rotation center position of the optical axis with respect to this, and this makes it possible to eliminate image blur due to the rotation of this photographing device, as well as the rotation center position of this photographing device and the photographing lens optical system. It is possible to eliminate the influence caused by the movement of the entrance portion of the system, and as a result, it is possible to more accurately calculate the image blur amount and to perform highly accurate image blur correction driving.

In addition, an image blur correction function-equipped exchange according to the present invention is provided.
According to the interchangeable lens , the calculating means for calculating the total weight when the camera body and the lens barrel forming the image capturing apparatus are combined, and the determining means for determining the rotation center of the image blur by the output from the calculating means. By attaching
The effects described above can be further exerted, the image blur amount can be accurately calculated, and highly accurate image blur correction driving can be performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an entire camera suitable for application of the present invention, showing an embodiment of an interchangeable lens with an image blur correction function according to the present invention.

FIG. 2 is a block diagram for explaining a main configuration of an interchangeable lens with an image blur correction function according to the present invention.

FIG. 3 is an explanatory diagram for explaining a relationship between a shake (change in angle of an optical axis) of a photographing device and an image shake of a subject image in the interchangeable lens with an image shake correction function according to the present invention.

FIG. 4 is a flowchart for explaining an operation sequence regarding image blur correction in the interchangeable lens with an image blur correction function according to the present invention.

[Explanation of symbols]

1 ... Camera body, 2 ... Camera side CPU (1st MCU;
(Including first storage means), 3 ... lens barrel, 4 ... lens barrel side CPU (second MCU; including second storage means), 5 ... angular velocity detection section, 6 ... image shake correction drive section, 7 ... Focus position detector, 8 ... Electrical contact.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G02B 7/04 G02B 7/04 E

Claims (4)

(57) [Claims] 1. An internal focusing optical system for imaging, a part of the internal focusing optical system, and a screen on which an image is formed by the internal focusing optical system for image blur correction. An image blur correction drive unit that relatively shifts, a calculation unit that calculates the distance between the rear main plane of the internal focus optical system and the image formation point, and rotational shake due to camera shake with respect to the internal focus optical system is detected. Angle change detection means, communication means for communicating information regarding the image blur correction with the camera body, rotation center determination means for determining the rotation center of image blur based on the information obtained by the communication means, and the calculation to the information from the means, and information from the angle change detecting means, comprises said on the basis of the information from the rotation center determining means image vibration drives and controls the image blur correction driving unit correction drive control unit Interchangeable lens with image blur correction function. 2. The interchangeable lens with an image blur correction function according to claim 1, further comprising a focus position information detection unit that detects focus position information of the internal focus optical system , wherein the image blur correction drive control unit includes: The image blur correction drive unit is drive-controlled based on the information from the focus position information detection unit, the information from the calculation unit, the information from the angle change detection unit, and the information from the rotation center determination unit. This is an interchangeable lens with image blur correction function. 3. The interchangeable lens with an image blur correction function according to claim 1, wherein the center of rotation is obtained based on a weight and a center of gravity of the interchangeable lens and a weight and a center of gravity of a camera body combined with the interchangeable lens. An interchangeable lens with an image blur correction function that is characterized by being used. 4. The interchangeable lens with an image blur correction function according to claim 1, 2, or 3, wherein the image blur correction drive control unit further includes a photographing distance (R).
And the distance between the photographic object and the front main plane of the photographic optical system (a)
An interchangeable lens with an image blur correction function, characterized in that the image blur correction drive section is driven and controlled based on the following.