JP2005049591A - Photographic lens and camera system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance adjustment accuracy in optical shake correction by introducing a new adjustment index. <P>SOLUTION: The photographic lens forming a subject image on the image pickup surface of a camera is equipped with a shake correction optical system, a vibration detection part, a shake correction control part, an information acquiring part and a characteristic adjustment part. The shake correction optical system is an optical system for optically correcting the image surface shake of the subject image on the image pickup surface. The vibration detection part detects vibration and outputs a vibration detection signal. The shake correction control part controls the position of the shake correction optical system based on the vibration detection signal so as to perform the optical shake correction. The information acquiring part acquires an image moving signal obtained by detecting the displacement between frames of the picked-up image of the camera as information. The characteristic adjustment part adjusts the control characteristic of the shake correction control part in a direction where the image moving signal is reduced at the time of optical shake correction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photographing lens and a camera system for optically correcting image plane blurring of a subject image with respect to an imaging surface.

2. Description of the Related Art Conventionally, a technique for optically correcting image plane blurring of a subject image due to camera shake using a blur correction optical system in a photographing lens is known.
In this type of conventional technology, first, vibrations of the photographing lens and the camera are detected by an angular velocity sensor. Based on this angular velocity, the photographic lens determines the position of the blur correction optical system (hereinafter referred to as “target drive position”) necessary to cancel out the image plane blur of the subject image, and the blur correction optical system is set to this target drive position. Follow-up control.

Patent Document 1 below discloses a technique for adjusting optical blur correction by using an image flow condition (hereinafter referred to as “image flow”) that appears in a still image due to image plane blurring as an adjustment index. That is, the blur width and contrast reduction of a still image caused by image flow are detected, and the optical blur correction is adjusted so that these are minimized.
JP-A-8-6094 (paragraphs 0027 to 0032)

As described above, in Patent Document 1, optical blur correction is adjusted using the degree of image flow of a still image as an adjustment index.
Usually, an image signal causing image flow has a continuous and gentle waveform change. Therefore, it is difficult to accurately measure the blur width of the image from this gentle waveform change. Therefore, it has been technically difficult to automate the adjustment work described above with a machine.

  Further, the image flow changes depending on the exposure time of the still image and the moving speed of the image plane blur. For example, in the case of slow motion image plane blurring, the amount of image movement during the exposure time becomes small, and the image flow becomes minute. Therefore, in the adjustment work of Patent Document 1, it is impossible to detect this low-speed image plane blur and improve it by adjusting.

  In order to detect such a low-speed image surface blur, a method of setting a long exposure time for a still image is conceivable. However, when the exposure time is increased, the image flow is greatly generated with respect to the image plane blur at the normal speed. As a result, the change in the waveform of the image signal becomes extremely small and is not suitable as the adjustment index described above.

  Further, when the adjustment work is automated by a machine, it is preferable to obtain the final adjustment value directly from the adjustment index by calculation. In the case of Patent Document 1, it is theoretically possible to obtain the final adjustment value directly from the blur width. However, the waveform variation of the image edge is dull due to the image flow, and the blur width cannot be measured accurately. In addition, the forcibly measured blur width has many errors, and is not suitable for the purpose of directly obtaining the final adjustment value by calculation.

  Furthermore, the direction of movement of the subject image (from the left to the right of the screen or from the right to the left) cannot be obtained as information from the still image that has caused the image flow. For this reason, it has not been possible to directly determine whether the gain to be adjusted should be increased or decreased.

  The above-described problem becomes more complicated and difficult when there are a plurality of adjustment portions for optical blur correction. In other words, Patent Document 1 does not have a measure for adjusting a plurality of adjustment points individually in order. Therefore, it is necessary to make adjustments while reciprocating a plurality of adjustment points many times. Therefore, it takes time and labor to properly adjust all the adjustment points.

Accordingly, an object of the present invention is to introduce a new adjustment index to increase the adjustment accuracy of optical blur correction.
Another object of the present invention is to provide a technique for directly determining an appropriate gain value using this adjustment index.
Another object of the present invention is to adjust a plurality of adjustment points individually and independently using this adjustment index.

  The present invention will be described below.

<Claim 1>
The invention described in claim 1 is a photographic lens for forming a subject image on an imaging surface of a camera, and includes a shake correction optical system, a vibration detection unit, a shake correction control unit, an information acquisition unit, and a characteristic adjustment unit.
This blur correction optical system is an optical system for optically correcting the image plane blur of the subject image on the imaging surface.
The vibration detection unit detects vibration and outputs a vibration detection signal.
The shake correction control unit controls the position of the shake correction optical system based on the vibration detection signal and performs optical shake correction.
The information acquisition unit acquires information on an image motion signal obtained by detecting the inter-frame displacement of the captured image of the camera.
The characteristic adjustment unit adjusts the control characteristic of the blur correction control unit in a direction in which the image motion signal is reduced during optical blur correction.

<Claim 2>
According to a second aspect of the present invention, in the photographing lens according to the first aspect, the characteristic adjusting unit adjusts the gain of the vibration detection signal in a direction in which the image motion signal is reduced.

<Claim 3>
According to a third aspect of the present invention, in the photographic lens according to the first or second aspect, the blur correction control unit includes a target drive position calculation unit, a position detection unit, and a drive unit.
The target drive position calculation unit calculates a target drive position of the shake correction optical system based on the vibration detection signal.
The position detector detects the position of the blur correction optical system and outputs it as a position detection signal.
The drive unit displaces the shake correction optical system according to the deviation between the position detection signal and the target drive position.
In this case, the characteristic adjustment unit adjusts the gain of the position detection signal in a direction to reduce the image motion signal.

<Claim 4>
According to a fourth aspect of the present invention, in the photographic lens according to the first aspect, the blur correction control unit includes a target drive position calculation unit, a position detection unit, and a drive unit.
The target drive position calculation unit calculates a target drive position of the shake correction optical system based on the vibration detection signal.
The position detector detects the position of the blur correction optical system and outputs it as a position detection signal.
The drive unit displaces the shake correction optical system according to the deviation between the position detection signal and the target drive position.
In this case, the characteristic adjustment unit individually performs the next gain adjustment.
(1) With the shake correction optical system stopped, the gain of the vibration detection signal is adjusted so that the image motion signal and vibration detection signal converted to the same scale match.
(2) Next, with the motion compensation optical system moved, the gain of the position detection signal is adjusted according to the image motion signal.

<Claim 5>
According to a fifth aspect of the present invention, in the photographing lens according to the fourth aspect, the characteristic adjusting unit performs gain adjustment in the following order.
(1) First, the gain of the vibration detection signal is adjusted so that the image motion signal and the vibration detection signal coincide with each other when the blur correction optical system is stopped.
(2) After that, with the optical blur correction performed, the position detection signal and the image motion signal converted to the same scale,
A = position detection signal / (image motion signal + position detection signal)
And the gain of the position detection signal is adjusted to A times.

<Claim 6>
The invention described in claim 6 is a camera system including a photographic lens, an imaging unit, and a motion detection unit.
This photographing lens is the photographing lens according to any one of claims 1 to 5.
The imaging unit captures a subject image formed on the imaging surface by the imaging lens.
The motion detection unit acquires a captured image from the imaging unit, detects inter-frame displacement of the captured image, and outputs it as an image motion signal.

<Claim 1>
According to the first aspect of the present invention, the optical blur correction is adjusted by using the image motion signal as an adjustment index.
The image motion signal is obtained by comparing the captured images of a plurality of frames and detecting the movement amount of the image pattern.

  In this case, by setting the exposure time of each captured image appropriately, the waveform change of the signal of each captured image can be kept sharp. Therefore, in the image motion signal, unlike the conventional image flow, it is possible to accurately detect the displacement amount of the image plane blur.

  Further, in the image motion signal, the moving direction of the image pattern can be detected from the temporal relationship of the captured image. As a result, it is also possible to determine the image plane blurring trajectory (movement vector), vibration state phase change, and the like from the image motion signal.

  Also, with image motion signals, it is possible to detect extremely low-speed image plane blurring with high accuracy, which was difficult to detect with conventional image flow, by increasing the time interval between frames by thinning between frames. You can also.

  Further, by detecting image motion signals for a plurality of types of inter-frame intervals, image plane blur can be detected over a very wide frequency band. In this case, the image motion signal is an optimum adjustment index that has not existed in the past in obtaining control characteristics for suppressing wide-band image plane blurring.

  Furthermore, in the present invention, the final adjustment target is to reduce the image motion signal in the optical blur correction. The image motion signal at the time of optical blur correction indicates residual blur that cannot be completely removed by the blur correction operation. Therefore, an excellent control characteristic that sufficiently suppresses the remaining blur can be easily realized by adjusting the control characteristic in the direction in which the image motion signal at the time of optical blur correction is reduced.

  Furthermore, since the image motion signal has accurate and detailed information as described above, it is possible to finely detect and determine the state of optical blur correction. Therefore, it is possible to adjust the control characteristics so as to correctly improve the anti-shake performance of the optical blur correction, reflecting these detection determinations.

<Claim 2>
According to the second aspect of the present invention, the gain of the vibration detection signal is adjusted in the direction of reducing the image motion signal. In the optical blur correction, feedback control of the blur correction optical system is performed with the vibration detection signal as an input. For this reason, if the gain of the vibration detection signal is inappropriate, the driving of the blur correction optical system becomes excessive and deficient, and appears as a residual blur in the captured image. This residual blur is detected as an image motion signal. Therefore, by adjusting the gain of the vibration detection signal in the direction of reducing the image motion signal, the inappropriate gain of the vibration detection signal can be accurately adjusted.

<Claim 3>
According to the third aspect of the present invention, the gain of the position detection signal is adjusted in the direction of reducing the image motion signal. In optical blur correction, the position detection signal is made to follow the target drive position. For this reason, if the gain of the position detection signal is inappropriate, the position of the blur correction optical system does not coincide with the target drive position, and appears as a residual blur in the captured image. This residual blur is detected as an image motion signal. Therefore, by adjusting the gain of the position detection signal in the direction of reducing the image motion signal, the inappropriate gain of the position detection signal can be accurately adjusted.

<Claim 4>
According to the fourth aspect of the present invention, the gain of the vibration detection signal is adjusted while the blur correction optical system is stopped. In this state, since the blur correction optical system is in a stopped state, only image plane blur corresponding to the vibration detection signal occurs. Therefore, the image motion signal in this state has a one-to-one correspondence with the vibration detection signal. Therefore, the gain of the vibration detection signal can be accurately adjusted by adjusting the gain of the vibration detection signal so that the image motion signal and the vibration detection signal converted to the same scale match.
Since this adjustment is performed independently of the gain adjustment of the position detection signal, the adjustment process can be performed simply and quickly.
Furthermore, in the invention of claim 4, the gain of the position detection signal is adjusted in a state where the blur correction optical system is moved. In this state, the subject image is shifted due to the movement of the blur correction optical system, and an image motion signal is generated. Therefore, the gain of the position detection signal can be adjusted independently according to the image motion signal.

At this time, it is preferable to make the photographing lens stationary with respect to the subject. In this case, an image motion signal is generated only due to the motion of the blur correction optics. Therefore, in this state, the image motion signal has a one-to-one correspondence with the position detection signal. Therefore, the gain of the position detection signal may be adjusted so that the image motion signal converted into the same scale matches the position detection signal. Such adjustment makes it possible to accurately adjust the gain of the position detection signal.
Also in this adjustment, since the gain adjustment of the position detection signal is performed independently of the gain adjustment of the vibration detection signal or the like, the adjustment process can be performed simply and quickly.

<Claim 5>
In the fifth aspect of the invention, first, the gain of the vibration detection signal is adjusted independently while the shake correction optical system is stopped.
Next, the gain of the position detection signal is adjusted in a state where optical blur correction is performed. At this time, the image motion vector corresponds to the remaining blur in the optical blur correction. In order to cancel this remaining blur, it is necessary to displace the blur correction optical system to the corresponding position of (image motion signal + position detection signal). For this purpose, A = the position detection signal / (the image motion signal + the position detection signal) is obtained for the position detection signal and the image motion signal converted to the same scale, and the gain of the position detection signal is adjusted to A times. That's fine.
By such an operation, it becomes possible to obtain the adjustment value of the position detection signal directly by calculation.
In particular, this adjustment procedure is completed in a short time by calculation while correcting camera shake. Therefore, this adjustment procedure is very excellent as an adjustment operation performed during actual photographing.

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

[Description of Embodiment Configuration]
FIG. 1 is a diagram showing a camera system 190 (including a photographing lens 190a) having an optical blur correction mechanism. Note that the actual camera system 190 corrects image plane blurring in two horizontal and vertical directions. However, in FIG. 1, only one axis of the optical blur correction mechanism is shown for the sake of simplicity.

Hereinafter, the structure of each part shown in FIG. 1 will be described.
The angular velocity sensor 10 detects the vibration of the camera system 190 as an angular velocity by Coriolis force or the like. The output of the angular velocity sensor 10 is converted into digital angular velocity data via the A / D converter 30 and the variable gain amplifier 35.
The reference value calculation unit 40 extracts a low frequency component from the angular velocity data output from the A / D conversion unit 30, and estimates a reference value of angular velocity (angular velocity data in a stationary state without vibration). Further, the reference value calculation unit 40 corrects this reference value using an image motion vector described later.

  The target drive position calculation unit 50 subtracts the reference value from the angular velocity data to obtain a true angular velocity that causes image plane blurring. The target drive position calculation unit 50 obtains the optical axis angle of the photographing lens 190a by integrating the true angular velocity. The target drive position calculation unit 50 determines the target drive position based on this optical axis angle. This target drive position is the position of the blur correction optical system 100 that cancels the displacement of the subject image at this optical axis angle.

Note that the target drive position calculation unit 50 acquires the focal length information 120, the photographing magnification information 130, and the optical information 140 of the shake correction optical system 100 via the MPU 200 for use in calculating the target drive position.
The focal length information 120 is information obtained from time to time from the encoder output of the zoom ring of the photographing lens 190a.
The photographing magnification information 130 is information obtained at any time from the lens position of the photographing lens 190a and the AF driving mechanism.
The optical information 140 of the blur correction optical system 100 is a blur correction coefficient (blur correction coefficient = image movement amount with respect to lens movement amount / lens movement amount), and is data stored in advance in the photographing lens 190a.

  Further, the photographing lens 190 a is provided with a position detection unit 90 for detecting the position of the blur correction optical system 100. The position detection unit 90 includes an infrared LED 92, a PSD (position detection element) 98, and a slit plate 94. The light of the infrared LED 92 passes through a slit hole 96 of a slit plate 94 provided in the lens barrel 102 of the shake correction optical system 100 and becomes spot light. This spot light reaches the PSD 98. The PSD 98 outputs a signal of the light receiving position of the spot light. This signal output is digitally converted via the A / D converter 110 and the variable gain amplifier 115, whereby a position detection signal of the blur correction optical system 100 is obtained.

The drive signal calculation unit 60 obtains a deviation between the position detection signal and the target drive position, and calculates a drive signal according to the deviation. For example, in the calculation of the drive signal, PID control is performed in which the proportional term, the integral term, and the derivative term of the deviation are added at a predetermined ratio.
The driver 70 causes a drive current to flow through the drive mechanism 80 in accordance with the obtained drive signal (digital signal).

  The drive mechanism 80 includes a yoke 82, a magnet 84, and a coil 86. The coil 86 is disposed in a magnetic circuit formed by the yoke 82 and the magnet 84 while being fixed to the lens barrel 102 of the shake correction optical system 100. By passing the driving current of the driver 70 through the coil 86, the blur correction optical system 100 can be moved in a direction orthogonal to the optical axis.

The blur correction optical system 100 is a part of the imaging optical system of the photographing lens 190a. By moving the blur correction optical system 100 to the target drive position and shifting the imaging position of the subject image, it is possible to suppress image plane blurring of the subject image.
The image sensor 150 captures a subject image formed on the imaging surface. In addition to being displayed on a monitor screen (not shown), the captured image is output to the motion vector detection unit 160.

  The motion vector detection unit 160 detects the image motion vector by detecting the inter-frame displacement of the captured image. The MPU 200 converts the image motion vector into the same scale as the reference value using the focal length information 120 and the photographing magnification information 130. The image motion vector converted in this way is used for reference value correction, gain adjustment, and the like in the reference value calculation unit 40 described above.

[Correspondence with Invention]
The correspondence relationship between the invention and this embodiment will be described below. Note that the correspondence relationship here illustrates one interpretation for reference, and does not limit the present invention.
The photographic lens described in the claims corresponds to the photographic lens 190a.
The shake correction optical system described in the claims corresponds to the shake correction optical system 100.
The vibration detection unit described in the claims corresponds to the angular velocity sensor 10.
The blur correction control unit includes a variable gain amplifier 35, a reference value calculation unit 40, a target drive position calculation unit 50, a drive signal calculation unit 60, a driver 70, a drive mechanism 80, a position detection unit 90, and a variable gain amplifier. 115.
The information acquisition unit described in the claims corresponds to the “function of acquiring an image motion vector from the motion vector detection unit 160” of the MPU 200.
The characteristic adjustment unit described in the claims corresponds to the “function of adjusting the gains of the variable gain amplifiers 35 and 115” of the MPU 200.
The target drive position calculation unit described in the claims corresponds to the target drive position calculation unit 50.
The position detector described in the claims corresponds to the position detector 90.
The drive unit described in the claims corresponds to the drive signal calculation unit 60, the driver 70, the variable gain amplifier 115, and the drive mechanism 80.
The camera system described in the claims corresponds to the camera system 190.
The motion detector described in the claims corresponds to the motion vector detector 160.
The imaging unit described in the claims corresponds to the imaging element 150.
The image motion signal described in the claims corresponds to a component in the same direction as the angular velocity of the image motion vector.
The position detection signal described in the claims corresponds to the position detection signal output from the variable gain amplifier 115.
The vibration detection signal described in the claims corresponds to the angular velocity data output from the variable gain amplifier 35.

[Explanation of optical image stabilization]
FIG. 2 is a flowchart showing an optical blur correction control operation.
First, the control operation of optical blur correction will be described with reference to FIG.

Step S11: The angular velocity output of the angular velocity sensor 10 is periodically A / D converted and output as angular velocity data from the variable gain amplifier 35.

Step S12: The reference value calculation unit 40 extracts a low frequency component from the angular velocity data, and estimates a reference value of the angular velocity data (angular velocity data at rest without blur).

Step S13: The reference value calculation unit 40 acquires information about an image motion vector V ′ described later from the MPU 200, and corrects the reference value Wo according to the following equation.
Wo ′ = Wo−Q · v ′ (1)
Where Q is the feedback gain of the image motion vector. v ′ is a component in the same direction as the angular velocity of the image motion vector V ′ (converted to the same scale as the angular velocity). The value of Q is determined from the standpoint of appropriately suppressing the overshoot of the reference value Wo ′ and appropriately shortening the settling time of the reference value Wo ′.

In general, if an error occurs in the reference value Wo ′, a residual blur occurs in the captured image in the optical blur correction. By detecting this residual blur as an image motion vector V ′ and feeding it back to the reference value by the above equation (1), the error of the reference value Wo ′ can be reduced.
In the optical blur correction, in order to improve the followability of the blur correction optical system 100, the target drive position and the reference value are updated at a sampling interval shorter than the image motion vector update interval. Therefore, a new image motion vector cannot be used every time the reference value is corrected every time. Therefore, the current image motion vector V ′ is repeatedly used until the next image motion vector is acquired.

Step S14: The target drive position calculation unit 50 subtracts the corrected reference value Wo ′ from the angular velocity data output from the variable gain amplifier 35 to obtain true angular velocity data that causes image plane blurring.

Step S15: The target drive position calculation unit 50 obtains the displacement amount of the optical axis angle of the photographing lens 190a by integrating the true angular velocity data. The target drive position calculation unit 50 obtains the position (so-called target drive position) of the blur correction optical system 100 necessary for canceling the displacement of the imaging position of the subject image from the value of the optical axis angle.
For example, the target drive position θ (T _k ) is calculated using the following equation.
C = f · (1 + β) ² / K (2)
θ (T _k ) = θ (T _k−1 ) + C · [W (T _k ) −Wo ′] (3)
Where f is the focal length, β is the imaging magnification, θ (T _k−1 ) is the previous target drive position, W (T _k ) is the latest angular velocity data, and K is the blur correction coefficient. The blur correction coefficient K is measured in advance based on the following equation.
K = (displacement of subject image) / (displacement of blur correction optical system 100)
Step S16: The drive signal calculation unit 60 acquires information about the target drive position from the target drive position calculation unit 50, and executes follow-up control so that the position detection signal of the blur correction optical system 100 matches the target drive position.

[Explanation of image motion vector calculation and gain adjustment]
Next, image motion vector calculation processing will be described.
FIG. 3 is a flowchart showing a procedure for calculating an image motion vector.
A series of operations shown in FIG. 3 is an operation that is performed whenever the image capturing operation of the image sensor 150 is performed, and an operation that is performed in parallel with the optical blur correction described above (FIG. 2).

Step S21: The image sensor 150 reads out the captured image for monitor display at high speed (30 frames / second) by thinning out the number of lines of the image.

Step S22: The motion vector detection unit 160 obtains a motion vector of the image from the inter-frame difference of the captured image. As such an image motion vector detection method, there is a method such as a block matching method.
In addition, you may obtain | require an image motion vector about the whole captured image. Or you may obtain | require an image motion vector about the partial area of a captured image.
Further, the image motion vector may be obtained individually for each axial direction (for example, vertical and horizontal) of optical blur correction. In this case, an image motion vector having image motion in each axis direction (displacement between frames) as an individual element is obtained.
Further, as the image motion vector, the displacement direction and the displacement amount of the captured image may be obtained by detecting inter-frame displacement of the captured image in a plurality of directions.
In the block matching method or the like, the inter-frame difference is obtained while shifting the captured image of each frame. It is preferable to obtain the inter-frame displacement that minimizes the inter-frame difference after performing the interpolated calculation of the inter-frame difference plot value finer than the pixel pitch. In this case, a precise image motion vector can be obtained with a resolution of about 1/10 of the pixel pitch.

Step S23: The MPU 200 acquires information on the focal length information 120 of the photographic lens 190a.

Step S24: The MPU 200 acquires the shooting magnification information 130 of the shooting lens 190a.

ただし、Ｖは換算前の画像動きベクトル、Ｖ′は換算後の画像動きベクトル、ｆは焦点距離、βは撮影倍率、およびＧは定数である。 Step S25: The image motion vector output by the motion vector detection unit 160 is information on displacement between frames of the captured image. Therefore, the MPU 200 converts the image motion vector into a scale having the same angular velocity as the reference value. For example, the following conversion formula is used.

However, V is an image motion vector before conversion, V ′ is an image motion vector after conversion, f is a focal length, β is a photographing magnification, and G is a constant.

Step S26: The MPU 200 updates the image motion vector held for correcting the reference value to the latest value V ′ obtained in Step S5.

Step S27: The MPU 200 determines whether or not to start the gain adjustment mode. This gain adjustment mode can be used, for example, immediately after the start of optical blur correction, when a decrease in optical blur correction performance is detected, immediately after the taking lens is replaced, when gain adjustment is instructed by a user operation, and when the power is turned on. Implemented in a timely manner, such as immediately after.
Here, when starting the gain adjustment mode, the MPU 200 shifts the operation to step S28.
On the other hand, when the gain adjustment mode is not started, the MPU 200 returns the operation to step S21.

Step S28: The MPU 200 determines whether or not the optical blur correction is operating stably. This is because the adjustment operation described later is hindered in a transient state or an abnormal state.
Here, when the optical blur correction is operating stably (so-called pull-in completion), the MPU 200 shifts the operation to step S29.
On the other hand, if the optical blur correction is not stably operated, the MPU 200 gives up the adjustment operation and returns the operation to step S21.

Step S29: Next, the MPU 200 determines whether or not the size of the image motion vector is equal to or less than the allowable value Th1. This allowable value Th1 is a value indicating the recognition limit of the remaining blur of the captured image indicated by the image motion vector. For example, the allowable value Th1 is a value determined according to the pixel pitch of the image sensor 150, the image print size, the image display size, and the like.
Here, when the magnitude of the image motion vector is equal to or smaller than the allowable value Th1, the MPU 200 shifts the operation to Step S30.
On the other hand, if the size of the image motion vector is larger than the allowable value Th1, the MPU 200 determines that an adjustment operation is necessary, and moves the operation to step S31.

Step S30: Here, it can be determined that the anti-vibration performance of the optical blur correction is extremely high and that the gain adjustment is unnecessary. Therefore, the MPU 200 completes the gain adjustment mode and returns the operation to step S21.

Step S31: Here, it can be determined that the gain adjustment is necessary because the image stabilization performance of the optical blur correction is not necessarily sufficient. Therefore, the MPU 200 compares the previous value and the latest value of the image motion vector.
If the image motion vector is smaller than the previous time, the MPU 200 determines that the previous gain adjustment increase / decrease direction is correct, and proceeds to step S32.
On the other hand, if the image motion vector is larger than the previous time, the MPU 200 shifts the operation to step S33.

Step S32: In this step, the residual blur indicated by the image motion vector is smoothly reduced. Therefore, the gain of the variable gain amplifier 35 and / or the variable gain amplifier 115 is changed by a predetermined step size in the same increase / decrease direction as the previous time. After this gain adjustment, the MPU 200 returns the operation to step S21.

Step S33: The MPU 200 determines whether or not the number of gain adjustments after starting the gain adjustment mode has exceeded a predetermined limit value.
If the gain adjustment count exceeds the limit value, the MPU 200 shifts the operation to step S34.
On the other hand, when the number of gain adjustments is equal to or less than the limit value, the MPU 200 shifts the operation to step S35.

Step S34: In this step, since the number of gain adjustments exceeds the limit value, it can be determined that further gain adjustment is unnecessary. Therefore, the MPU 200 completes the gain adjustment mode and returns the operation to step S21.

Step S35: Here, since the image motion vector has increased from the previous time, the MPU 200 changes the gain of the variable gain amplifier 35 and / or the variable gain amplifier 115 by a predetermined step size in the increase / decrease direction opposite to the previous time. To do. The step size is preferably reduced every time the increase / decrease direction is reversed. After this gain adjustment, the MPU 200 returns the operation to step S21.
As a result of the above-described operation, asymptotic adjustment of the control characteristics (here, gain) is performed together with the calculation processing of the image motion vector.

[Explanation of other gain adjustment modes]
FIG. 4 is a flowchart for explaining the operation in another gain adjustment mode. This gain adjustment mode is also used, for example, immediately after the start of optical blur correction, when a decrease in optical blur correction performance is detected, when gain adjustment is instructed by a user operation, when a photographic lens is replaced, and when the power is turned on. Implemented in a timely manner, such as immediately after.
Hereinafter, the operation will be described along the step numbers shown in FIG.

Step S41: The MPU 200 first stops the optical blur correction and holds the blur correction optical system near the center.

Step S42: The MPU 200 acquires angular velocity data output from the variable gain amplifier 35.

Step S43: The MPU 200 converts the angular velocity data into an image plane blurring scale and integrates it to obtain a subject image displacement Δ1 caused by the vibration of the photographing lens 190a.

Step S44: The MPU 200 repeatedly executes Steps S42 and S43 until the next captured image is output from the image sensor 150. As a result, the displacement Δ1 of the subject image generated between the frames of the captured image is obtained.
On the other hand, when the next captured image is output from the image sensor 150, the MPU 200 shifts the operation to step S45.

Step S45: The MPU 200 acquires information about an image motion vector, which is the inter-frame displacement of the captured image, from the motion vector detection unit 160.

Step S46: The MPU 200 obtains the displacement Δ2 on the image plane of the captured image from the component in the same direction as the angular velocity of the motion vector.

Step S47: Here, since the shake correction optical system is in a stationary state, the displacement Δ1 and the displacement Δ2 are essentially the same. The reason why the displacements Δ1 and Δ2 are shifted is that the gain of the angular velocity data is inappropriate. Therefore, the gain γ1 of the angular velocity data (the gain γ1 of the variable gain amplifier 35) is adjusted by the following equation with reference to the displacements Δ1 and Δ2.
Γ1 after adjustment = γ1 before adjustment × (Δ2 / Δ1)
With such adjustment, the gain adjustment of the angular velocity data is completed.

Step S48: Subsequently, the MPU 200 starts optical blur correction. The MPU 200 waits until the optical blur correction is pulled into a stable state, and then proceeds to step S49.

Step S49: The MPU 200 acquires information about the position detection signal output from the variable gain amplifier 115.

Step S50: The MPU 200 obtains a displacement Δ3 that is a shift amount of the imaging position by the blur correction optical system by converting the position detection signal of the blur correction optical system into a scale on the image plane. This displacement Δ3 has a positive or negative sign depending on the direction of shift of the imaging position.

Step S51: The MPU 200 repeatedly executes Steps S49 and S50 until the next captured image is output from the image sensor 150. As a result, a displacement Δ3 between frames of the captured image is obtained.
On the other hand, when the next captured image is output from the image sensor 150, the MPU 200 shifts the operation to step S52.

Step S52: The MPU 200 acquires information about an image motion vector, which is the inter-frame displacement of the captured image, from the motion vector detection unit 160.

Step S53: The MPU 200 converts a component in the same direction as the position detection signal of the motion vector into a scale on the image plane, and obtains a residual blur displacement Δ2. This displacement Δ2 has a positive or negative sign according to the moving direction of the remaining blur.

Step S54: Here, the gain γ1 of the angular velocity data has already been adjusted in step S47 described above. Therefore, the target drive position calculated from the angular velocity data having an accurate gain is also an adjusted value.
Here, the remaining blur of the captured image indicates a displacement Δ2. Therefore, ideally, the position of the blur correction optical system must be controlled so as to cause an image shift of (Δ2 + Δ3).

  On the other hand, the position detection signal and the target drive position are controlled to coincide with each other by optical blur correction. Therefore, when the target drive position is converted on the image plane, the value is substantially equal to the displacement Δ3. Since the target drive position value has been adjusted as described above, it cannot be changed by adjustment.

From the above, it is only necessary to output a position detection signal corresponding to the displacement Δ3 at the position of the blur correction optical system that causes an image shift of the ideal image plane displacement (Δ2 + Δ3). Therefore, the gain γ2 (gain γ2 of the position detection signal) of the variable gain amplifier 115 is adjusted by the following equation.
Γ2 after adjustment = γ2 × Δ3 / (Δ2 + Δ3) before adjustment

Such adjustment completes the gain adjustment of the position detection signal.
In particular, in this adjustment, it is possible to adjust the gain of the vibration detection signal (here, the angular velocity) and the gain of the position detection signal in appropriate order based on the image motion signal as an absolute reference.

  Furthermore, in this adjustment, since the adjustment value can be specified by calculation, the adjustment is completed in a very short time. In the second half of the adjustment procedure, adjustment can be performed while performing optical blur correction. Therefore, if the adjustment mode is implemented during actual photographing, the adjustment is completed in such a short time that the user is not conscious. That is, the second embodiment is a very excellent adjustment mode as an adjustment mode performed during actual photographing.

[Supplementary items of the embodiment]
In the above-described embodiment, the image motion vector is generated based on the captured image of the image sensor. However, the present invention is not limited to this. For example, the captured image may be generated by performing photoelectric conversion using a split photometry mechanism, a focus detection mechanism, a color measurement mechanism, a finder mechanism, or the like of the camera system. By generating an image motion vector from this type of captured image, the present invention can be implemented in a “silver salt camera” or a “single-lens reflex electronic camera”.

  Furthermore, if the camera has a continuous shooting performance of about 1 to 8 frames per second, an image motion signal at a sampling interval necessary for gain adjustment can be obtained. Therefore, the present invention can also be applied to a type of camera that continuously performs optical blur correction while continuously shooting.

  In addition, image motion signals may be detected for a plurality of types of frame intervals, and the detection result may be used as an adjustment index. From this detection result, it is possible to identify wide-band image plane blurring. Therefore, by using this detection result as an adjustment index, it is possible to satisfactorily adjust the control characteristic of optical blur correction over a wide band.

  Furthermore, in the above-described embodiment, the photographic lens 190a and the camera system 190 may be configured integrally. Further, the photographic lens 190a and the camera system 190 may be detachable. Note that when the photographic lens 190 a and the camera system 190 are attached and detached, the block that generates the image motion signal may be installed in either the photographic lens 190 a or the camera system 190. For example, a mode in which a block that generates an image motion signal is installed on the camera system 190 side, and a block that converts the image motion signal into the same scale as the reference value is installed on the photographing lens 190a side.

  In the above-described embodiment, the angular velocity is detected as the vibration detection signal. However, the present invention is not limited to the detection of the angular velocity, and it is sufficient to detect a vibration component that can estimate the displacement of the imaging position of the subject image. For example, an acceleration acting on the camera system, an angular acceleration, a centrifugal force, an inertial force, or the like may be detected as a vibration detection signal.

  In the embodiment described above, in order to increase the adjustment accuracy, a vibration generating mechanism such as a motor having an eccentric weight may be provided in the photographing lens 190a or the camera system 190 to forcibly apply vibration.

  In the above-described embodiment, the present invention is applied to gain adjustment, but the present invention is not limited to this. In general, the present invention can be applied to general adjustment of control characteristics of optical blur correction.

  As described above, the present invention is a technique that can be used for an optical apparatus having an optical blur correction function.

It is a block diagram concerning the present invention. It is a flowchart which shows the control operation | movement of an optical blurring correction. It is a flowchart which shows the calculation procedure of an image motion vector. It is a flowchart explaining operation | movement of another gain adjustment mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Angular velocity sensor 20 Amplification part 30 A / D conversion part 35 Variable gain amplifier 40 Reference value calculation part 50 Target drive position calculation part 60 Drive signal calculation part 70 Driver 80 Drive mechanism 90 Position detection part 115 Variable gain amplifier 150 Image pick-up element 160 Motion Vector detection unit 190 Camera system 190a Shooting lens 200 MPU

Claims (6)

A photographic lens that forms a subject image on the imaging surface of a camera,
A blur correction optical system for optically correcting an image plane blur of the subject image on the imaging surface;
A vibration detector that detects vibration and outputs a vibration detection signal;
A shake correction control unit for controlling the position of the shake correction optical system based on the vibration detection signal and performing optical shake correction;
An information acquisition unit for acquiring information on an image motion signal obtained by detecting an inter-frame displacement of a captured image of the camera;
A photographic lens, comprising: a characteristic adjusting unit that adjusts a control characteristic of the blur correction control unit in a direction in which the image motion signal is reduced when the optical blur correction is performed. The photographic lens according to claim 1,
The photographic lens, wherein the characteristic adjustment unit adjusts a gain of the vibration detection signal in a direction in which the image motion signal is reduced. The photographic lens according to claim 1 or 2,
The blur correction control unit
A target drive position calculation unit that calculates a target drive position of the blur correction optical system based on the vibration detection signal;
A position detection unit that detects the position of the blur correction optical system and outputs the position detection signal;
A drive unit that displaces the blur correction optical system according to a deviation between the position detection signal and the target drive position;
The characteristic adjusting unit is
An imaging lens, wherein a gain of the position detection signal is adjusted in a direction in which the image motion signal is reduced. The photographic lens according to claim 1,
The blur correction control unit
A target drive position calculation unit that calculates a target drive position of the blur correction optical system based on the vibration detection signal;
A position detection unit that detects the position of the blur correction optical system and outputs the position detection signal;
A drive unit that displaces the blur correction optical system in accordance with a deviation between the position detection signal and the target drive position;
The characteristic adjusting unit is
In a state in which the blur correction optical system is stopped, the gain of the vibration detection signal is adjusted so that the image motion signal converted to the same scale and the vibration detection signal match.
A photographic lens, wherein a gain of the position detection signal is adjusted according to the image motion signal in a state where the blur correction optical system is moved. The photographic lens according to claim 4,
The characteristic adjusting unit is
With the shake correction optical system stopped, adjust the gain of the vibration detection signal so that the image motion signal and the vibration detection signal match,
Then, with the optical blur correction performed, for the position detection signal and the image motion signal converted to the same scale,
A = the position detection signal / (the image motion signal + the position detection signal)
And a gain of the position detection signal is adjusted to A times. The taking lens according to any one of claims 1 to 5,
An imaging unit that captures a subject image formed on an imaging surface by the imaging lens;
A camera system comprising: a motion detection unit that acquires a captured image from the imaging unit, detects inter-frame displacement of the captured image, and outputs the displacement as the image motion signal.

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