Patent Description:
In a central projection type optical system, an image point movement on an imaging plane under camera shakes differs between a central part of an image (image center) and a periphery of the image (image periphery). As illustrated in <FIG>, an image-point moving amount in the image periphery is larger than that at the image center, and thus the image points in the image periphery remain more significantly moved than those of the image center, as illustrated in <FIG>, after the image stabilization. Japanese Patent Laid-Open No. ("<CIT> discloses an image pickup apparatus that provides an image stabilization at an image point position in the image periphery based on a difference between an image blur amount at the image center and an image blur amount at a predetermined image point position caused by the central projection method.

The image pickup apparatus disclosed in <CIT> calculates a correction amount for the image stabilization at the predetermined image point position using an image height dependent expression in an ideal optical system without considering the aberration of the central projection method. Thus, if the image stabilization is performed based on the correction amount calculated by the above expression for an actual optical system having a distortion residue, a correction residue or overcorrection occurs. Moreover, as illustrated in <FIG>, at an image point position having an image-point moving direction that has a skew relationship with an image-point moving direction at the image center, the image point moves with a vector different from that of the image center and it is thus difficult to properly calculate the correction amount at that image point position only by the above expression.

<CIT> further discloses a method of more properly providing an image stabilization by adding design value information on a distortion of an optical system stored in a memory to the calculated correction amount, but this method complicates a calculation process. Furthermore, it also remains difficult to calculate the correction amount at the image point position with the image-point moving direction that has the skew relationship with the image-point moving direction at the image center.

<CIT> discloses a blur correction device as defined in the preamble of claim <NUM>.

The present invention provides a control apparatus, an image pickup apparatus, a lens apparatus, a control method, and a program, each of which can easily and satisfactorily provide an image stabilization at a predetermined image point position including a center of an optical axis.

The present invention in its first aspect provides a control apparatus as specified in claims <NUM> to <NUM>.

The present invention in its second aspect provides an image pickup apparatus as specified in claim <NUM>.

The present invention in its third aspect provides a lens apparatus as specified in claim <NUM>.

The present invention in its fourth aspect provides a control method as specified in claim <NUM>.

The present invention in its fifth aspect provides a program as specified in claim <NUM>.

Referring now to the accompanying drawings, a detailed description will be given of embodiments according to the present invention. Corresponding elements in respective figures will be designated by the same reference numerals, and a duplicate description thereof will be omitted.

In the following description, in a three-dimensional orthogonal coordinate system (X-axis direction, Y-axis direction, and Z-axis direction), the X-axis direction is a long side direction of the imaging plane, the Y-axis direction is a short side direction of the imaging plane, and the Z-axis direction is an optical axis direction of the optical system.

<FIG> is a schematic configuration diagram of an image pickup system <NUM> according to this embodiment. The image pickup system <NUM> includes a lens apparatus <NUM> and an image pickup apparatus <NUM>. The lens apparatus <NUM> includes an imaging optical system <NUM>, a lens microcomputer <NUM>, a lens shift type image stabilization (referred to as OIS hereinafter) encoder <NUM>, an OIS driver <NUM>, an OIS actuator <NUM>, and a lens memory (storage unit) <NUM>. The image pickup apparatus <NUM> includes an image sensor (image pickup element) <NUM>, a camera microcomputer <NUM>, a display/operation unit <NUM>, and a recording medium <NUM>. The image pickup apparatus <NUM> further includes a gyro sensor <NUM>, an acceleration sensor <NUM>, an image-sensor shift type image stabilization (referred to as IIS hereinafter) encoder <NUM>, an IIS driver <NUM>, an IIS actuator <NUM>, and a camera memory (storage means) <NUM>. IIS is an image stabilization (IS) performed by moving the image sensor <NUM>. The lens microcomputer <NUM> and the camera microcomputer <NUM> may be configured as a control apparatus separate from the lens apparatus <NUM> and the image pickup apparatus <NUM>, respectively.

The imaging optical system <NUM> includes a focus optical system <NUM>, a magnification varying (zoom) optical system <NUM>, a diaphragm (aperture stop) <NUM>, and an OIS optical system <NUM>. The imaging optical system <NUM> forms an object image on an imaging plane of the image sensor <NUM> using light from the object at an in-focus position within a set angle of view. The focus optical system <NUM> provides focusing. The magnification varying optical system <NUM> provides a magnification variation (zooming) in order to change an imaging angle of view. The diaphragm <NUM> adjusts a light amount captured from the object. The OIS optical system <NUM> provides the image stabilization to an image blur that occurs during still or motion image capturing by decentering itself from the optical axis of the imaging optical system <NUM>. Here, OIS is an image stabilization performed by moving the OIS optical system <NUM>.

The lens microcomputer <NUM> controls the OIS optical system <NUM>. More specifically, the lens microcomputer <NUM> determines an OIS driving amount of the OIS actuator <NUM> using an image-stabilization (IS) driving amount from the camera microcomputer <NUM> and a position signal from the OIS encoder <NUM> that detects the position of the OIS optical system <NUM>. The OIS driving amount is determined so as not to exceed a movable range of the OIS actuator <NUM>. When the OIS actuator <NUM> receives an OIS driving amount signal from the OIS driver <NUM>, the OIS actuator <NUM> moves the OIS optical system <NUM> in a direction including a component of a direction orthogonal to the Z-axis direction to decenter it from the optical axis of the imaging optical system <NUM> and thereby provides the image stabilization. That is, the OIS actuator <NUM> functions as one of the image stabilizers that provide image stabilization.

The lens memory <NUM> stores optical design information on the imaging optical system <NUM>. The optical design information includes information on a tilt-image shift sensitivity of the imaging optical system <NUM> for each image height (information on an image shift sensitivity to a tilt of the imaging optical system <NUM> according to an image point position of the imaging optical system <NUM>). The information on the tilt-image shift sensitivity is information obtained by using the designed value of the imaging optical system <NUM> and includes the influence of the distortion of the imaging optical system <NUM>. Use of the information on the tilt-image shift sensitivity can provide a satisfactory image stabilization at a predetermined image point position of the imaging optical system <NUM>, when the image pickup system <NUM> generates a rotation blur so that the X-Y plane orthogonal to the optical axis is tilted to the optical axis. The camera memory <NUM> may store the optical design information on the imaging optical system <NUM> including information on the tilt-image shift sensitivity. Both the lens memory <NUM> and the camera memory <NUM> may store the optical design information on the imaging optical system <NUM> including the information on the tilt-image shift sensitivity.

The imaging optical system <NUM> has a distortion DIST(h) expressed by the following expression: <MAT> <MAT> where f is a focal length of the imaging optical system <NUM>, and ω is a half angle of view, h is a distance (real image height) from the optical axis of the imaging optical system <NUM> to a position on the image plane where a principal ray having the half angle of view ω incident from the object plane is imaged, and h0 is an ideal image height of the central projection method.

Having a distortion means that a distortion amount at any image height within the imaging range is not zero. The imaging optical system having the distortion includes an imaging optical system having a magnification varying function and a focusing function and having distortion in a certain magnification varying state or in-focus state.

The image sensor <NUM> includes a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, or another image sensor. The image sensor <NUM> converts an object image formed on the imaging plane of the image sensor <NUM> by the imaging optical system <NUM> into an electric signal, and outputs it as an image signal. The image signal as an analog signal is converted into a digital signal by an unillustrated A/D converter and then output.

The camera microcomputer <NUM> controls the entire image pickup system <NUM>. For example, the camera microcomputer <NUM> reads out the image signal as image data from the image sensor <NUM>. The camera microcomputer <NUM> performs processing such as image processing for the image data based on the optical design information, displaying the image data on the display/operation unit <NUM>, and saving the image data in the recording medium <NUM>. The camera microcomputer <NUM> issues instructions, such as focusing, zoom magnification changing, and diaphragm adjusting of the imaging optical system <NUM>, to the lens microcomputer <NUM>. Some of the settings relating to the processing may be changed by an operation unit such as a display/operation unit <NUM> and an unillustrated button.

The camera microcomputer <NUM> acquires the IS driving amount (image-stabilization driving amount that is used for the image stabilization by the image stabilizer) according to a flow of <FIG> is a flowchart illustrating a control method for acquiring an IS driving amount by the camera microcomputer <NUM>. In the first acquiring step S1, the camera microcomputer <NUM> functions as the first acquiring task and acquires the information on the image shift sensitivity to the tilt of the imaging optical system <NUM> according to the image point position of the imaging optical system <NUM>, which information includes the influence of the distortion of the imaging optical system <NUM>. In the second acquiring step S2, the camera microcomputer <NUM> functions as a second acquiring task, and acquires an IS driving amount according to a predetermined image point position using the information on the image shift sensitivity according to the predetermined image point position. The camera microcomputer <NUM> may calculate the IS driving amount, or may acquire it from a table stored in a server, memory, or the like. In this embodiment, the camera microcomputer <NUM> functions as the first acquiring task and the second acquiring task, but the lens microcomputer <NUM> may function as the first acquiring task and the second acquiring task.

The gyro sensor <NUM> outputs information on an angular velocity of the image pickup system <NUM> as a motion detecting signal. The acceleration sensor <NUM> outputs information on a moving amount of the image pickup system <NUM> in a translational direction as a motion detecting signal. The camera microcomputer <NUM> when receiving the motion detecting signal transmitted from each sensor, transmits the IS driving amount to the lens microcomputer <NUM> or the IIS control unit <NUM> in the camera microcomputer <NUM> so as to provide the image stabilization to an object image for a motion of the image pickup system <NUM>. In the image stabilization, either OIS or IIS may be performed, or both OIS and IIS may be performed with a determined share of image stabilization (such as <NUM>% of OIS and <NUM>% of IIS).

The IIS control unit <NUM> controls the image sensor <NUM>. More specifically, the IIS control unit <NUM> determines the IIS driving amount of the IIS actuator <NUM> using the IS driving amount from the camera microcomputer <NUM> and the position signal from the IIS encoder <NUM> that detects the position of the image sensor <NUM>. The IIS driving amount is determined so as not to exceed the movable range of the IIS actuator <NUM>. When the IIS actuator <NUM> receives the IIS driving amount signal from the IIS driver <NUM>, it moves the image sensor <NUM> in a direction including a component of a direction perpendicular to the Z-axis direction to decenter it from the optical axis of the imaging optical system <NUM> and provides the image stabilization. That is, the IIS actuator <NUM> functions as one of the image stabilizers that provide the image stabilization.

The lens apparatus <NUM> may include a gyro sensor <NUM> and an acceleration sensor <NUM>. In this case, in the OIS, the lens microcomputer <NUM> determines the OIS driving amount using the IS driving amount acquired using the motion detecting signals output from these sensors and the position signal from the OIS encoder <NUM>.

A description will now be given of processing during the image stabilization at a predetermined image point position. When the gyro sensor <NUM> or the acceleration sensor <NUM> detects a motion of the image pickup system <NUM>, each sensor outputs the motion detecting signal (information on a blur) to the camera microcomputer <NUM>. The camera microcomputer <NUM> acquires the IS driving amount using the information on the tilt-image shift sensitivity stored by the lens memory <NUM>, IS position information on the imaging plane, and the motion detecting signals. The camera microcomputer <NUM> transmits the acquired IS driving amount to the lens microcomputer <NUM> or the IIS control unit <NUM>.

In this embodiment, the tilt-image shift sensitivity is an image-point moving amount in a direction orthogonal to a predetermined rotation axis when the imaging optical system <NUM> is tilted to that rotation axis orthogonal to the optical axis of the imaging optical system <NUM> on the imaging plane. <FIG> illustrates a relationship between the image height in the image-point moving direction at the image center and the tilt-image shift sensitivity (image-point moving amount) when the imaging optical system <NUM> according to this embodiment is tilted. As illustrated in <FIG>, as the image height increases, the image-point moving amount increases when the imaging optical system <NUM> is tilted, which is designed to optically correct the aberration by the central projection method. This embodiment can acquire the image-point moving amount for each image height when rotation blur occurs without performing calculation processing using the image height expression based on the projection method and the distortion amount, because this embodiment utilizes the tilt-image shift sensitivity acquired by using the designed value of the imaging optical system <NUM>. The tilt-image shift sensitivity according to this embodiment is a value obtained by dividing by <NUM>° the image-point moving amount when the imaging optical system <NUM> is tilted by <NUM>° relative to the predetermined rotation axis. The tilt angle of the imaging optical system <NUM> is not limited to <NUM>° and may be properly set.

<FIG> explains an image point movement at a predetermined image point position against an image point movement at an image center when the rotation blur occurs about the Y-axis, and schematically illustrates a state where a stationary (nonblurred) object image <NUM> is turned into an object image <NUM> distorted into a trapezoidal shape due to the image blur. In a wide-angle lens that optically corrects the distortion by the central projection method, the trapezoidal distortion like the object image <NUM> deteriorates when the rotation blur occurs. The image blur occurs when each image point on the imaging plane moves according to an image-point moving vector indicated by an arrow.

A description will now be given of an image-point moving amount tx0 in the +X-axis direction at a center position O on the imaging plane, which is the image center when a rotation blur amount ωy about the Y-axis occurs, and an image-point moving amount tx at a predetermined image point position A.

The image-point moving amount tx0 is expressed by the following expression (<NUM>): <MAT> where LS is a tilt-image shift sensitivity at an image height of <NUM>.

Assume the imaging plane (X-Y plane) in a polar coordinate system (R-Θ coordinate system) with a center position O as an origin, and (r, θ) is a coordinate of the predetermined image point position A. That is, in this embodiment, the predetermined image point position A is a position on the imaging plane represented by a plurality of parameters. The image height on the horizontal axis in <FIG> is an image height hr in the R direction in the polar coordinate system illustrated in <FIG>. A tilt-image-shift sensitivity coefficient kLS_r(hr) at an image height hr against the tilt-image shift sensitivity LS is expressed by the following expression (<NUM>): <MAT> where LSr(hr) is a tilt-image shift sensitivity at an image height hr.

The image-point moving amount tx0 is expressed by the following expressions (<NUM>) to (<NUM>) using a parallel component trx0 parallel to a straight line OA and a vertical component tθx0 perpendicular to the straight line OA: <MAT> <MAT> <MAT>.

The parallel component trx0 has a positive sign in the direction separating from the center position O (R direction), and the vertical component tθx0 has a positive sign in the direction orthogonal to the R direction toward the counterclockwise direction about the center position O (θ direction). The R direction and the θ direction are also referred to as a meridional direction and a sagittal direction, respectively.

Next, consider the image-point moving amount tx at the predetermined image point position A. The parallel component trx parallel to the straight line OA is affected by the tilt-image shift sensitivity LSr(r) at the image height r, and the vertical component tθx perpendicular to the straight line OA is affected by the tilt-image shift sensitivity LS at the image height of <NUM>. From the above, the image-point moving amount tx is expressed by the following expressions (<NUM>) to (<NUM>) using the parallel component trx and the vertical component tex: <MAT> <MAT> <MAT>.

In this way, the image-point moving amount tx at the predetermined image point position A when the rotation blur amount ωy occurs about the Y-axis can be calculated. Similarly, an image-point moving amount ty at the predetermined image point position A in the polar coordinate system when the rotation blur amount ωx occurs about the X-axis is expressed by the following expressions (<NUM>) to (<NUM>) using a parallel component try parallel to the straight line OA and a vertical component tθy perpendicular to the straight line OA: <MAT> <MAT> <MAT>.

As described above, the image-point moving amount t at the predetermined image point position A when the rotation blur amount (ωx, ωy) occurs about the predetermined rotation axis orthogonal to the optical axis on the imaging plane can be expressed by the following expressions (<NUM>) to (<NUM>) using a parallel component tr parallel to the straight line OA and a vertical component tθ perpendicular to the straight line OA. <MAT> <MAT> <MAT>.

Coefficients (K<NUM>, K<NUM>, K<NUM>, K<NUM>) in the expressions (<NUM>) and (<NUM>) are given as follows: <MAT> <MAT> <MAT> <MAT>.

As expressed by the expressions (<NUM>) to (<NUM>), the image-point moving amount t includes correction coefficient information (K<NUM>, K<NUM>, K<NUM>, K<NUM>) including the tilt-image shift sensitivity and the position information (r, θ) at the image point position, and a rotation blur amount (ωx, ωy). In this embodiment, the lens memory <NUM> previously stores as the information on the tilt-image shift sensitivity a correction coefficient table of the correction coefficient information (K<NUM>, K<NUM>, K<NUM>, K<NUM>) in a matrix format defined by the image point position illustrated in <FIG>. This configuration can easily obtain the image-point moving amount t at the predetermined image point position A when the rotation blur amount (ωx, ωy) occurs. An interval between adjacent image point positions in the correction coefficient table is properly set. The correction coefficient table may be managed not in the polar coordinate system but in the orthogonal coordinate system.

The information on the tilt-image shift sensitivity may include the tilt-image shift sensitivity for each image height in order to reduce the information stored in the lens memory <NUM>, or may provide the image-point moving amount t using position information on a predetermined image point position that is a target of the image stabilization. The position information on the image point position may be information on a polar coordinate system or information on a predetermined coordinate system (such as an orthogonal coordinate system).

This embodiment can switch a setting mode of the image pickup system <NUM> to an image-center IS mode that sets a predetermined image point position (image stabilization position) that is a target of the image stabilization to the center of the imaging plane, or an IS spot setting mode that can set an image stabilization point to a predetermined image point position. In a case where the IS spot setting mode is set, the image stabilization position can be set on the display/operation unit <NUM>. The position settable by the display/operation unit <NUM> may be linked with the image point position where autofocus is performed or the image point position where automatic photometry (light metering) is performed. The image point position where the autofocus is performed may be a position automatically detected by the pupil detection, person detection, or the like. The IS position information (r, θ) on the imaging plane is sent to the camera microcomputer <NUM>, and the correction coefficient information to be used is selected from the correction coefficient table.

The gyro sensor <NUM> detects angular velocities about a plurality of rotation axes of the image pickup system <NUM> and outputs information on the rotation blur amount as a motion detecting signal. In this embodiment, the gyro sensor <NUM> detects angular velocities about the X-axis and the Y-axis, and outputs information on the rotation blur amount (ωx, ωy). The acceleration sensor <NUM> detects accelerations in a plurality of axial directions of the image pickup system <NUM> and outputs information on the translational blur amount as a motion detecting signal. In this embodiment, the acceleration sensor <NUM> detects accelerations in the X-axis and Y-axis directions, and outputs information on the translational blur amount (ax, ay). The gyro sensor <NUM> may include a plurality of sensors, each of which detects an angular velocity about a single axis. Similarly, the acceleration sensor <NUM> may include a plurality of sensors, each of which detects acceleration in a single direction.

The camera microcomputer <NUM> acquires an IS driving amount using the information on the tilt-image shift sensitivity, the IS position information, and the motion detecting signal. For example, in a case where an image blur at a predetermined image point position A due to the rotation blur is corrected by IIS, the image sensor <NUM> may be moved so as to cancel the image-point moving amount t. An IS driving amount x in the X-axis direction and an IS driving amount y in the Y-axis direction of the IIS actuator <NUM> are expressed by the following expressions (<NUM>) and (<NUM>): <MAT> <MAT>.

Coefficients (K'<NUM>, K'<NUM>, K'<NUM>, K'<NUM>) in the expressions (<NUM>) and (<NUM>) are given as follows: <MAT> <MAT> <MAT> <MAT>.

<FIG> illustrates a ratio and direction of the image-point moving amount of the correction residue generated at each image point when the image blur at the predetermined image point position A is corrected by IIS in this embodiment. As illustrated in <FIG>, the image blur at the set predetermined image point position A is satisfactorily corrected while the image blur at the image center is allowed. Since the image point movement of the same motion vector as that at the image point position A occurs at the image point position A' that is point-symmetric to the image point position A' with respect to the image center as the origin, the image blur at the image point position A' is also corrected. Hence, a distribution of the image blur amount in the entire image can be maintained low and the image blur of the entire image can be reduced by properly setting an image stabilization position to a predetermined position outside the optical axis to the extent that the image blur at the image center does not pose strangeness.

As expressed by the expressions (<NUM>) and (<NUM>), the IS driving amount (x, y) includes the correction coefficient information (K'<NUM>, K'<NUM>, K'<NUM>, K'<NUM>) and the rotation blur amount (ωx, ωy). Thus, the correction coefficient table of the correction coefficient information (K'<NUM>, K'<NUM>, K'<NUM>, K'<NUM>) in a matrix format may be stored as the information on the tilt-image shift sensitivity in the lens memory <NUM>. By using K'<NUM> or the like instead of the above correction coefficient information (K<NUM>, K<NUM>, K<NUM>, K<NUM>), the IS driving amount (x) at the predetermined image point position A when the rotation blur amount (ωx, ωy) occurs can be easily obtained.

In the case of OIS, the OIS eccentric (decentering) sensitivity TS(h) for each image height of the OIS optical system <NUM> increases as the image height becomes higher, so that the IS driving amount may be acquired based on the OIS eccentric sensitivity TS(h). Thereby, the image stabilization can be performed with high accuracy.

Regarding the image blur derived from the translation blur, the IS driving amount may be acquired using the information on the translation blur amount from the acceleration sensor <NUM>. The IS driving amount for the translation blur may be acquired by converting the translation blur amount (ax, ay) into the rotation blur amount (ωx, ωy) using the in-focus object distance information. In a case where the rotation blur and translation blur occur at the same time, the IS driving amount may be acquired by adding the IS driving amount for the translation blur and the IS driving amount for the rotation blur. The IS driving amount for the translation blur at the predetermined image point position may be acquired by multiplying the converted rotation blur amount by the correction coefficient included in the information on the tilt-image shift sensitivity.

In a case where the in-focus position is close to the short distance end, the translational component of the object plane generated by the rotation blur becomes large. The IS driving amount for the image blur caused by the translational component according to the object distance may be acquired by the above method.

The tilt-image shift sensitivity changes according to the object distance and the focal length (imaging angle of view) on which the imaging optical system <NUM> is focused. In this embodiment, the lens memory <NUM> stores a plurality of correction coefficient tables that differ according to an in-focus position determined by the focus optical system <NUM> and a focal length determined by the magnification varying optical system <NUM>. Thereby, the image stabilization can be satisfactorily provided at a predetermined image point position even during the magnification variation (zooming) or focusing.

The lens apparatus <NUM> may be detachably attached to the image pickup apparatus <NUM>. In this case, the information on the proper tilt-image shift sensitivity may be used for each lens apparatus <NUM>. Thereby, even where a different lens apparatus <NUM> is attached to the image pickup apparatus <NUM> and used, the image blur at a predetermined image point position can be satisfactorily corrected.

This embodiment expands the information on the tilt-image shift sensitivity is wider than the first embodiment. Since the configuration of the image pickup system <NUM> and the processing in the image stabilization in this embodiment are the same as those in the first embodiment, a detailed description thereof will be omitted.

In this embodiment, a distortion amount by which the object image of the imaging optical system <NUM> is deformed into a barrel shape is larger than that in the first embodiment. In an imaging optical system with a small distortion amount, an image-point moving amount at any image point position in a direction orthogonal to an image-point moving direction at the image center when the imaging optical system is tilted is almost similar to an image-point moving amount at the image center. On the other hand, the imaging optical system <NUM> according to this embodiment has a large distortion amount. Then, the image-point moving amount in the direction orthogonal to the image-point moving direction at the image center when the imaging optical system <NUM> is tilted becomes smaller as a position is more separated from the image center. Thus, in this embodiment, the lens memory <NUM> stores the information on a significant tilt-image shift sensitivity for the image-point moving amount in the direction orthogonal to the image-point moving direction at the image center caused by the rotation blur.

<FIG> illustrates a relationship between the image height in the direction orthogonal to the image-point moving direction at the image center and the tilt-image shift sensitivity (image-point moving amount) when the imaging optical system <NUM> according to this embodiment is tilted. <FIG> illustrates a ratio and direction of the image-point moving amount of the correction residue generated at each image point when the image blur at the image center according to this embodiment is corrected by IIS. An image height in a direction orthogonal to an image-point moving direction at the center position O on the imaging plane on the horizontal axis illustrated <FIG> is an image height in a direction orthogonal to the R direction in the polar coordinate system. As illustrated in <FIG>, in this embodiment, the tilt-image shift sensitivity LSe(he) at the image height he in the direction orthogonal to the image-point moving direction at the image center when the imaging optical system <NUM> having a large distortion amount is tilted is smaller than the tilt-image shift sensitivity LS at the image center. Therefore, if the image stabilization is provided at an image point position where the image height is high with the IS driving amount acquired with the tilt-image shift sensitivity LS at the image center, the overcorrection occurs as illustrated in <FIG>.

Accordingly, this embodiment adds the tilt-image shift sensitivity to the information described in the first embodiment, and creates information that includes the influence of the image-point moving amount for each image height in a direction parallel to the rotation axis when the imaging optical system <NUM> is tilted. The tilt-image shift sensitivity coefficient kLS_θ(hθ) at the image height he against the tilt-image shift sensitivity LS at the image center is expressed by the following expression (<NUM>): <MAT>.

When a rotation blur amount (ωx, ωy) occurs, a parallel component tr parallel to the straight line OA, which is a polar coordinate system component of the image-point moving amount t at a predetermined image point position A, and a vertical component tθ perpendicular to the straight line OA are expressed by the following expressions (12a) and (13a), respectively: <MAT> <MAT>.

Coefficients (K1, K2, K3, K4) in the expression (12a) and (13a) are given as follows: <MAT> <MAT> <MAT> <MAT>.

An IS driving amount x in the X-axis direction and an IS driving amount y in the Y-axis direction of the IIS actuator <NUM> are expressed by the following expressions (15a) and (16a): <MAT> <MAT>.

Coefficients (K'<NUM>, K'<NUM>, K'<NUM>, K'<NUM>) in the expressions (15a) and (16a) are given as follows: <MAT> <MAT> <MAT> <MAT>.

As described above, this embodiment acquires the IS driving amount based on the tilt-image shift sensitivities for each image height in the direction parallel to the rotation axis and the direction orthogonal to the rotation axis. Thereby, even when the image pickup system <NUM> uses the imaging optical system <NUM> having a large distortion amount, the image stabilization can be satisfactorily provided at a predetermined image point position.

An optical system designed by a fisheye lens projection method (such as an equidistant projection method and an equisolid angle projection method) also has a significant tilt-image shift sensitivity characteristic against the image-point moving amount in the θ direction. Thus, the IS driving amount may be acquired based on the tilt-image shift sensitivities for each image height in the R and θ directions.

In a case where a large image-stabilization angle is guaranteed as a specification of the image stabilization mechanism, the IS driving amount may be determined based on the tilt-image shift sensitivity according to this embodiment.

Referring now to the accompanying drawings, a description will be given of examples of the imaging optical system <NUM> according to the present invention.

<FIG>, <FIG>, and <FIG> are sectional views of the optical system L0 according to Examples <NUM> to <NUM> at a wide-angle end in an in-focus state on an object at infinity, respectively. An arrow illustrated in each sectional view represents a moving locus of each lens unit during zooming from the wide-angle end to a telephoto end. <FIG> is a sectional view of the optical system L0 according to Example <NUM> in an in-focus state on an object at infinity. An arrow illustrated in <FIG> represents a moving locus of the lens unit during focusing from infinity to a short distance end (or close) end. The optical system L0 according to each example is used for an image pickup apparatus such as a digital video camera, a digital still camera, a broadcasting camera, a surveillance camera, and a smartphone camera.

In each sectional view, a left side is an object side and a right side is an image side. The optical system L0 according to each example includes a plurality of lens units. As used herein, a lens unit is a group of lenses that move or stand still integrally during zooming, focusing, or image stabilization. That is, in the optical system L0 according to each example, a distance between adjacent lens units changes during zooming or focusing. The lens unit may include one or more lenses. The lens unit may include a diaphragm (aperture stop).

SP denotes the diaphragm. IP denotes an image plane, on which an imaging plane of an image sensor (photoelectric conversion element), such as a CCD sensor or a CMOS sensor, is disposed. The OIS optical system is eccentric to the optical axis of the optical system L0 during OIS.

The projection method of the optical system L0 according to Examples <NUM>, <NUM>, and <NUM> is a central projection method (Y = ftanθ). The projection method of the optical system L0 according to Example <NUM> is an equisolid angle projection method (Y = <NUM>·f·sin(θ/<NUM>)).

<FIG>, <FIG>, and <FIG> are aberration diagrams of the optical system L0 according to Examples <NUM> to <NUM> at the wide-angle end in the in-focus state on the object at infinity, respectively. <FIG> is an aberration diagram of the optical system L0 according to Example <NUM> in the in-focus state on the object at infinity.

In the spherical aberration diagram, Fno denotes an F-number and indicates the spherical aberration amounts for the d-line (wavelength <NUM>) and the g-line (wavelength <NUM>). In the astigmatism diagram, S denotes an astigmatism amount in a sagittal image plane, and M denotes an astigmatism amount in a meridional image plane. The distortion diagram illustrates a distortion amount for the d-line. A chromatic aberration diagram illustrates a lateral chromatic aberration for the g-line. ω denotes an imaging half angle of view (°).

Numerical examples <NUM> to <NUM> corresponding to Examples <NUM> to <NUM>, respectively, will be illustrated below.

In the surface data in each numerical example, r denotes a radius of curvature of each optical surface, and d (mm) denotes an on-axis distance (a distance on the optical axis) between an m-th surface and an (m+<NUM>)-th surface, where m is a surface number counted from the light incident surface. nd denotes a refractive index of each optical member for the d-line, and vd denotes an Abbe number of the optical member. The Abbe number vd of a certain material is expressed as follows: <MAT> where Nd, NF, and NC are refractive indexes for the d-line (wavelength <NUM>), F-line (wavelength <NUM>), and C-line (wavelength <NUM>) in the Fraunhofer lines.

In each numerical example, all values of d, a focal length (mm), an F-number, and a half angle of view (°) are values when the optical system L0 according to each example is focused on an object at infinity (infinity object). A backfocus (BF) is a distance on the optical axis from the final surface of the lens (the lens surface closest to the image plane) to the paraxial image plane in terms of an air conversion length. An overall optical length is a length obtained by adding the backfocus to a distance on the optical axis from the frontmost surface of the lens (the lens surface closest to the object) to the final surface of the lens.

In a case where the optical surface is aspherical, an asterisk * is added to the right side of the surface number. The aspherical shape is expressed as follows: X=(h<NUM>/R)/[<NUM>+{<NUM>-(<NUM>+k)(h/R)<NUM>}<NUM>/<NUM>]+A4×h<NUM>+A6×h<NUM>+A8×h<NUM>+A10×h<NUM>+A12×h<NUM> where X is a displacement amount from the surface vertex in the optical axis direction, h is a height from the optical axis in the direction perpendicular to the optical axis, R is a paraxial radius of curvature, k is a conical constant, A4, A6, A8, A10, and A12 are aspherical coefficients of each order. "e±XX" in each aspherical coefficient means "× <NUM>±XX.

The tilt-image shift sensitivity data and the eccentric sensitivity data for the eccentricity of the OIS optical system are illustrated in each numerical example. An acquiring method of them will be described with reference to <FIG>.

<FIG> are ray tracing diagrams in the optical system L0 according to Example <NUM> of a principal ray of the d-line corresponding to each angle of view incident from the object plane (a principal ray having a half angle of view <NUM> and a principal ray having a half angle of view ω). <FIG> illustrate the stationary optical system L0, in a tilted state by a tilt angle ωx about the X-axis using as a center an intersection between the image plane IP and the optical axis, and an eccentric state in which the OIS optical system is eccentric by an eccentric amount of y in the Y-axis direction.

The tilt-image shift sensitivity for each image height in the tilt direction (R direction) can be acquired by dividing by the tilt angle ωx the image-point moving amount ΔyLSr(hr) as a difference of an imaging position on the image plane IP corresponding to each half angle of view between <FIG>. The tilt-image shift sensitivity for each image height in the direction orthogonal to the tilt direction is acquired by using the image-point moving amount ΔyLSθ for each image height he in the X-axis direction. The tilt-image shift sensitivity according to each example is acquired from the image-point moving amount in a case where the optical system L0 is tilted by <NUM>°. The tilt angle ωx has a positive sign in the counterclockwise direction and a negative sign in the clockwise direction in <FIG>. The image-point moving amount Δy has a positive sign in the upward direction and a negative sign in the downward direction.

The eccentric sensitivity of the OIS optical system for each image height in the eccentric direction (R direction) is acquired by dividing by the eccentricity y of the OIS optical system the image-point moving amount ΔyTSr(hr) as a difference of the imaging position on the image plane IP corresponding to each half angle of view between <FIG> and <FIG>. In each example, the eccentric sensitivity of the OIS optical system for each image height in the direction orthogonal to the eccentric direction is acquired by using the image-point moving amount ΔyTSθ for each image height he in the X-axis direction. The eccentric sensitivity data for the eccentricity of the OIS optical system in each example is acquired from the image-point moving amount in a case where the OIS optical system is eccentric by <NUM>.

As described above, the configuration according to the present invention can easily and satisfactorily provide an image stabilization at a predetermined image point position including the center of the optical axis.

Each embodiment expresses the information on the image shift sensitivity to the tilt of the imaging optical system <NUM> according to the image point position as a correction coefficient table of the correction coefficient information in a matrix format defined by the image point position, but the present invention is not limited to this embodiment. It may be the tilt-image shift sensitivity LSr(hr) or LSe(he) or the off-axis correction coefficient information acquired from the tilt-image shift sensitivity. That is, the information on the image shift sensitivity may be information that can provide a moving amount of a predetermined image point position to the tilt of the imaging optical system <NUM>.

Each embodiment has described the tilt-image shift sensitivity as information for each image height in the direction (R direction) orthogonal to the tilt rotation axis of the imaging optical system <NUM> and in the direction parallel to the rotation axis of the tilt. However, the tilt-image shift sensitivity may be information determined for each image point position over the entire imaging plane against a predetermined tilt direction. In that case, it may be the tilt-image shift sensitivity directly acquired from the image-point moving amount over the entire imaging plane acquired using the designed value of the imaging optical system <NUM>.

Each numerical example may acquire the image point position using the imaging position of the principal ray, but may acquire it using the peak position of MTF (Modulation Transfer Function).

The camera microcomputer <NUM> may perform image stabilization using an electronic image stabilization function that changes the effective pixel area of the image sensor <NUM>. That is, the camera microcomputer <NUM> may function as one of the image stabilizers.

Each of the above embodiments can provide a control apparatus, an image pickup apparatus, a lens apparatus, a control method, and a program, each of which can easily and satisfactorily provide an image stabilization to a predetermined image point position including a center of an optical axis.

Claim 1:
A control apparatus (<NUM>, <NUM>) comprising at least one processor or circuit configured to execute a plurality of tasks including:
a first acquiring task configured to acquire information on an image shift sensitivity (LS) to a tilt of an imaging optical system (<NUM>) corresponding to an image point position (A) of the imaging optical system on an image plane (X-Y), which information includes an influence of a distortion of the imaging optical system; and
a second acquiring task configured to acquire an image-stabilization driving amount that is used for an image stabilization by an image stabilizer (<NUM>, <NUM>) configured to provide the image stabilization,
wherein the second acquiring task acquires the image-stabilization driving amount corresponding to a predetermined image point position on the image plane using the information on the image shift sensitivity corresponding to the predetermined image point position;
characterized in that
the first acquiring task is further configured to acquire the information on the image shift sensitivity from a memory (<NUM>, <NUM>) storing the information on the image shift sensitivity as information (K1 - K4; K1' - K4') determined for each position (<NUM>, <NUM>, <NUM>) on the image plane.