JP2014048545A - Image capturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for enabling smooth photographing by reducing an unnecessary mechanism movement of an image capturing device having an image sensor moving mechanism which enables a second shooting mode for taking multiple frames while moving an image sensor in addition to a first shooting mode for normal shooting.SOLUTION: An image capturing device includes; an image sensor 8 on which an object light flux forms an image; focus detection means 22; first moving means 11 for moving the image sensor along an optical axis; a focusing lens 13 which makes the object light flux form an image on an imaging surface of the image sensor in accordance with a signal from the focus detection means; and second moving means 14 for moving the focusing lens along the optical axis. Control means 18 has a function for switching between a first shooting mode, for shooting without moving the image sensor, and a second shooting mode, for taking multiple frames while moving the image sensor, before shooting. An expected imaging plane in the second shooting mode is at a different position along the optical axis from an expected imaging plane in the first shooting mode.

Description

The present invention relates to an imaging apparatus such as a still camera or a video camera apparatus, and more particularly to an imaging apparatus capable of imaging by moving an imaging element in the optical axis direction of a lens.

In recent years, due to an increase in the number of pixels in a captured image and the like, further improvement in autofocus accuracy is desired in a single-lens reflex digital camera. However, it is also conceivable that fluctuation factors such as the environment, accumulative part accuracy, etc. will not match the reduced pixel pitch. As described above, it is becoming difficult to achieve further improvement in accuracy in the conventional method in which the focus lens is open-controlled by phase difference AF detection. As one of the solutions, in addition to the conventional autofocus mechanism by driving the focus lens, the imaging with a so-called hybrid type autofocus device provided with a moving mechanism of the image sensor for further focus fine adjustment A device has been proposed.

Patent Document 1 discloses the following method in an imaging system that performs focus adjustment by moving both a lens and an imaging device. That is, since the position of the best imaging plane of the taking lens in the fully open state and the position of the best imaging plane at the aperture value at the time of actual exposure are different, the taking lens is first moved to the former position and then taken. Immediately before shooting, the image sensor is moved and corrected by the difference between the former and the latter, and the image is taken.

JP 2006-251033 A

As a method of moving the image sensor, in addition to shooting on the planned imaging plane of the focus lens, images taken at a position moved by a predetermined amount before and after the shooting are also taken, and those images are evaluated later. There is a so-called focus bracket photographing method for recording and storing the best image. In the focus bracket method, after taking into account the variation width of the above-mentioned photographic lens, camera mechanism system, distance measurement system elements, etc., the focus image and the front focus image are shifted back and forth from the planned imaging plane by that width. Also, shoot together with the shot image on the planned imaging plane. Therefore, even if the above-described variation occurs in the imaging apparatus, the rear focus image or the front focus image may be a just focus image. This method has an advantage that the conventional phase-difference AF method can be used as it is because the calculation processing of the image sensor during photographing is unnecessary. On the other hand, since multiple shots are taken, there may be a problem with the time difference between the first shot frame and the subsequent frame, and the AF operation may take longer than the conventional lens drive method using the phase difference method. This is disadvantageous in scenes that require high-speed continuous shooting.

As a countermeasure for high-speed continuous shooting, an image pickup apparatus having a mode for taking an image without moving the image pickup element while having an image pickup element moving mechanism is also conceivable. However, in that case, depending on the stand-by position of each image sensor when shooting without moving and when shooting while moving, there is a possibility that the operation is wasted and smooth operation cannot be performed. For example, if the start position is on the planned imaging plane, the imaging device may be moved forward once to perform back focus side imaging, and then retracted to schedule imaging plane imaging, followed by front focus side imaging. . Thus, it is necessary to reverse the moving operation once. In order to increase the overall speed, it is necessary to perform this reversal operation rapidly. To that end, problems such as driving force, operation sound, durability of the mechanism, and increase in operation time can be considered.

Further, since the image sensor is movable by the image sensor moving mechanism, there is a concern that the imaging surface accuracy of the image sensor may be reduced as compared with the case where the image sensor is directly fixed to a conventional main body or the like. Here, the imaging surface accuracy mainly refers to the degree of perpendicularity or tilting of the imaging surface with respect to the optical axis. If this is high, the focus is evenly focused to the periphery of the captured image. Blur occurs. However, the prior art disclosed in the above-mentioned Patent Document 1 does not disclose a technique for solving the problem related to the imaging surface accuracy of the imaging element moving mechanism. Accordingly, an object of the present invention is to provide an image pickup apparatus having an image pickup element moving mechanism that enables smooth operation with reduced movement waste of the image pickup element moving mechanism and enables high-quality image pickup in a plurality of scenes. is there.

An image pickup apparatus according to the present invention includes an image pickup element on which a subject luminous flux formed through an optical means is imaged, a focus detection means, a first moving means for moving the image pickup element in an optical axis direction, and the focus detection means. A focus lens that forms an image of the subject light beam on the imaging surface of the image sensor based on the signal; a second moving unit that moves the focus lens in the optical axis direction; and a control unit. The control means executes shooting by switching the shooting mode between a first shooting mode for shooting without moving the image sensor and a second shooting mode for shooting a plurality of frames by moving the image sensor. The second imaging mode has a planned imaging plane that is different from the planned imaging plane in the first imaging mode in the optical axis direction.

According to the present invention, in the imaging apparatus having the imaging element moving mechanism that enables the second imaging mode in addition to the normal imaging that is the first imaging mode, smooth imaging with suppressed wasteful movement can be performed. It was. In addition, even with an image sensor movement mechanism, if a mechanical lock means or abutment means that increases the accuracy of the imaging surface is provided, it is possible to perform shooting that is less likely to cause one-side blur, resulting in a plurality of shooting scenes. A high-quality image can be obtained.

FIG. 3 is a developed perspective view of a main part of the imaging apparatus according to the first embodiment. FIG. 3 is a cross-sectional view of the imaging standby state in the first imaging mode of the imaging apparatus of Embodiment 1. FIG. 3 is a partial front view of a shooting standby state in the first shooting mode of the imaging apparatus according to the first embodiment. FIG. 5 is a cross-sectional view of a rear focus side shooting standby state in a second shooting mode of the imaging apparatus according to the first embodiment. FIG. 6 is a cross-sectional view of the imaging apparatus of Embodiment 1 in a standby state for standby imaging on a planned imaging plane in a second imaging mode. FIG. 6 is a cross-sectional view of a front focus side shooting standby state in the second shooting mode of the imaging apparatus according to the first embodiment. 1 is a block diagram illustrating a configuration of an imaging apparatus according to a first embodiment. 3 is a flowchart 1 of the operation of the imaging apparatus according to the first embodiment. 2 is a flowchart 2 of the operation of the imaging apparatus according to the first embodiment. FIG. 3 is a schematic diagram illustrating an arrangement on an optical axis of elements of the imaging apparatus according to the first embodiment. Sectional drawing of the front focus side imaging | photography standby state at the time of the 2nd imaging | photography mode of the imaging device of Example 2. FIG. FIG. 6 is a front view of a front focus side shooting standby state in a second shooting mode of the imaging apparatus according to the second embodiment. 10 is a flowchart 1 of the operation of the imaging apparatus according to the second embodiment. 9 is a flowchart 2 of the operation of the imaging apparatus according to the second embodiment. FIG. 6 is a cross-sectional view illustrating a moving state of an imaging element of an imaging apparatus according to Embodiment 3. FIG. 6 is a front view of a shooting standby state of the imaging apparatus according to the third embodiment. 10 is a flowchart 1 of the operation of the imaging apparatus according to the third embodiment. 9 is a flowchart 2 of the operation of the imaging apparatus according to the third embodiment. Sectional drawing at the time of locking of the imaging device of Example 4. FIG. FIG. 6 is a cross-sectional view of the imaging apparatus according to the fourth embodiment during wobbling. 10 is a flowchart of the operation of the imaging apparatus according to the fourth embodiment.

The present invention switches between a first shooting mode for shooting without moving an image sensor on which a subject luminous flux forms an image through optical means and a second shooting mode for shooting a plurality of frames by moving the image sensor. Is possible. The second imaging mode is characterized by having a scheduled imaging plane that is different from the scheduled imaging plane in the first imaging mode in the optical axis direction. More specifically, for example, in the second shooting mode, the focus lens is controlled so that the intermediate position of the moving range of the image sensor becomes the planned imaging plane. Moreover, the 2nd imaging | photography mode can further be equipped with the 1st locking means which determines the plane of the imaging surface of an image pick-up element. The first lock means is movable between a lock position that determines the plane of the image pickup surface of the image pickup element by contacting the image pickup element or its holding plate and an unlock position that allows the image pickup element to move in the optical axis direction. It is. The first locking means can adjust the position where it abuts against the image sensor or its holding plate. There is further provided means for wobbling the image sensor, and second lock means for locking the position of the image sensor when the image sensor stops wobbling and unlocking the image sensor when the image sensor starts wobbling. You can also. In this case, the control means controls the means for wobbling the image sensor so as to resume wobbling in synchronization with the unlocking of the second locking means. The first locking means can be rotated coaxially with the optical axis so as to move between the locked position and the unlocked position. Further, the first or second locking means can be slid so as to approach or move away from the optical axis, and can be moved between the locked position and the unlocked position. The control means can evaluate the captured images of a plurality of frames in the distance measurement area of the focus detection means, and select an image having a high evaluation value from the plurality of images based on the result of the image evaluation.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
Example 1
Hereinafter, with reference to FIG. 1 to FIG. 10, an imaging apparatus according to Embodiment 1 of the present invention will be described. The image pickup apparatus of this embodiment can generate image information by photoelectrically converting a subject image using an image pickup device such as a CCD sensor or a CMOS sensor, and can record the image information on an electronic recording medium such as an arbitrary memory. It is a digital imaging device.

(Configuration of Example 1)
FIG. 1 is a developed perspective view of the main part of the imaging apparatus of the present embodiment, and FIG. 2 includes the optical axis in a shooting standby state in the first shooting mode (shooting mode in which shooting is performed without moving the image sensor). FIG. 3 is a front view of the main part in the state of FIG. 1. 4, 5, and 6, the imaging device in the second imaging mode (imaging mode in which a plurality of frames are captured by moving the imaging device) is shown on the lens side (rear focus side) of the planned imaging plane, It is sectional drawing of the state just before imaging | photography which moved to the planned image plane and the back side (front focus side). FIG. 7 is a block diagram of the entire image pickup apparatus, FIGS. 8 and 9 are flowcharts of the operation of the image pickup apparatus, and FIG. 10 is a schematic diagram showing the distance relationship of each element on the optical axis. 1 to 7, reference numeral 1 denotes a main body that is an image pickup apparatus, and reference numeral 2 denotes a photographic lens that can be attached to and detached from the main body 1, and includes optical means for forming an image on the image pickup surface of the image pickup device 8. In addition, a focus lens 13 serving as a lens that is driven for focusing an image by a part of the optical means, a lens motor 14 that is a focus lens driving means, a lead screw 15, and a moving unit 16 are provided.

Reference numeral 3 shown in FIG. 7 denotes a release button provided on the main body and serving as a two-stage switch. The state where the release button 3 is pushed down to the first level is called half-press (SW1), and in the half-pressed state, photometry and distance measurement are performed. Further pressing from the state of SW1 up to the second level is called full pressing (SW2), and shooting is performed by pressing fully. Reference numeral 4 denotes a shutter base plate fixed to the main body 1 and includes a shutter blade 4 a that travels up and down to expose the image sensor 8. On the shutter base plate 4, a mirror 5, a guide shaft 7, a cam motor 11, an adjustment screw 17 and the like are supported and fixed. A mirror 5 switches the incident light of the photographing lens 2 to a finder side (observation position) (not shown) or the image sensor 8 side. The mirror 5 swings up and down so as to advance and retreat with respect to the photographing optical path by reciprocatingly rotating about a rotation shaft (not shown) provided on the shutter base plate 4. The mirror 5 is arranged at a 45 ° angle position that is an observation position in the standby state, and a part thereof is a half mirror, and the transmitted light beam is reflected by the sub-mirror 6 on the back surface, and the distance measuring sensor 22 that is a focus detection unit. The autofocus optical system that leads to A phase difference detection operation is performed in the distance measuring sensor 22 which is a distance measuring means.

Reference numeral 7 denotes a guide shaft, and two parallel guide shafts 7 are fixed vertically to the shutter base plate 4, one passes through the fitting hole 8b of the holding plate 8a without play, and the other one has a long hole 8c. It penetrates and functions as a rotation stopper. Thus, the image pickup device 8 can be smoothly advanced and retracted in the axial direction while preventing rotation. However, since the guide shaft 7 is sufficiently thin, the plane of the holding plate 8a is not determined, it can be tilted freely, and only the position within the plane of the image sensor 8 is determined. Reference numeral 8 denotes an image sensor, which converts an image projected on the imaging surface into an electric signal. The image pickup device 8 is fixed completely parallel to the holding plate 8a and advances and retreats in the optical axis direction. The image sensor 8 includes two types of shutters. One is a shutter blade 4a as a mechanical shutter for dust prevention, and the other has a function of an electronic front curtain as an electronic shutter that starts capturing of an image signal and an electronic rear curtain that stops capturing. Reference numeral 8a denotes a holding plate that is integrally attached to the image pickup device 8, and has three cutout portions 8d in the periphery, and three flat portions 8e that the spring 9 presses on the back side.

Reference numeral 9 denotes a compression spring as urging means, one end of which is fixed to the main body 1 and arranged at three equal angular intervals around the optical axis, and the other end is a flat portion on the back side of the holding plate 8a. 8e is always pushed forward, which is the direction in which the taking lens 2 is arranged. That is, it is a driving force for moving the image sensor 8 forward, and in FIG. 2, the spring 9 presses the image sensor 8 and the holding plate 8 a against the abutting portion of the adjustment screw 17 to form and hold the plane of the image sensor 8. Have sufficient biasing force to The compression spring 9 is gradually compressed when the imaging element 8 and the holding plate 8a are pressed by the cam 11a and moved backward.

Reference numeral 10 denotes a mode switch. Here, when a signal reaches the system control unit 18 every time the user presses the push switch, the first shooting mode in which shooting is performed without moving the image sensor 8 or the image sensor 8 is moved step by step. To switch to the second shooting mode for shooting a plurality of times. This mode selection is confirmed by a display (not shown). The first and second shooting modes will be described later.

Reference numeral 11 denotes a cam motor in which a cam 11a is fixed to a rotation shaft. Here, three are fixed to the shutter base plate 4 by using a stepping motor whose rotation amount and speed can be controlled. The cam motor 11 is reciprocally rotated or stopped at a predetermined amount and a predetermined speed by pulse control from the system control unit 18. Reference numeral 11a denotes a cam made of a material having good sliding properties. The cam 11 rotates in the range of zero to about 90 degrees by the rotation of the cam motor 11, and the smooth cam surface is held by the biasing force of the spring 9 through the holding plate 8a. It is made to contact | abut to the plane of 8a. Therefore, the image pickup device 8 and the holding plate 8a can be moved back and forth in the optical axis direction without play with respect to the rotation angle of the cam motor 11. Here, it is assumed that the cam motor 11 has a sufficient detent torque so that the cam motor 11 is not reversed by the biasing force of the spring 9 regardless of whether the cam motor 11 is energized. Therefore, the imaging element 8 and the holding plate 8a are moved by pulse control to the front photographing lens 2 side (leftward in FIG. 2) or rearward (rightward in FIG. 2) according to the forward and reverse rotation amounts of the cam motor 11. It is assumed that the cam lift amount of the cam 11a is sufficient for the movement of the image sensor 8 and the holding plate 8a. Although the rotation direction varies depending on the motor arrangement, the rotation direction of the motor when the image sensor 8 and the holding plate 8a move backward is referred to as normal rotation, and the rotation direction when the image pickup device 8 and the holding plate 8a move forward is referred to as reverse rotation. The spring 9, the cam motor 11, and the cam 11a constitute a first moving unit that moves the image sensor 8 in the optical axis direction.

Reference numeral 12 denotes a position sensor, which is a detection means, and outputs a signal when the holding plate 8a is at the frontmost standby position (A position) on the lens side, using a photo reflector. Reference numeral 13 denotes a focus lens for focusing the photographing lens 2. The lead screw 15 attached to the rotating shaft of the lens motor 14 that is a stepping motor that reciprocally rotates engages with the engaging portion of the moving portion 16, and the focus lens 13 fixed to the moving portion 16 moves back and forth. The lens motor 14, the lead screw 15, and the moving unit 16 constitute a second moving unit that moves the focus lens 13 in the optical axis direction. That is, the stepping motor rotates by the number of pulses calculated by the system control unit 18 based on the phase difference detection result by the distance measuring sensor 22, and the focus lens 13 moves forward from the initial position at infinity (here, the right end in the figure). To do. In the present embodiment, the planned imaging plane of the focus lens 13 can be set at two positions, the A position in the optical axis direction and the B position shifted by a predetermined amount from the A position. Accordingly, the movable region of the focus lens 13 at the A position is set to be longer by the difference between the A position and the B position, unlike at the B position.

Reference numeral 17 denotes an adjusting screw that is an adjusting means, which has an abutting portion that is an abutting means at its tip, and is arranged on the shutter base plate 4 at three positions at the center of the image sensor at an equal angular interval of 120 degrees. Since the adjustment screw 17 changes the position of the abutting portion in the optical axis direction by rotating, the position of the holding plate 8a in contact with the adjustment screw 17 changes in the optical axis direction. Therefore, a predetermined plane is formed by the three adjustment screws 17, and the squareness of the image sensor 8 with respect to the optical axis can be optimally adjusted by adjusting the rotation. For example, in the manufacturing process of the main body 1, this adjustment work is performed in the optical axis direction while referring to image signals such as the center and the periphery of the image sensor 8 with reference to a mount surface (not shown) that is a mounting surface of the photographing lens 2. Distance, inclination, and the like are precisely performed by rotating the three adjusting screws 17. The position where the imaging element 8 and the holding plate 8a are abutted becomes the foremost end of the movement range on the optical axis and is the A position. This position is one of the two planned imaging planes of the focus lens 13 in this embodiment.

In the block diagram of FIG. 7, reference numeral 18 denotes a system control unit which is a control unit, which includes a reset unit for performing a reset described later, an exposure control unit, and the like. The system control unit 18 includes a microcomputer unit including a CPU, and executes a built-in program. In addition, a sequence such as photometry and distance measurement is started by a signal from the release button 3. Further, in response to the signal from the position sensor 12, it is determined whether or not the holding plate 8a is currently in the standby position (position A). Further, the distance to the subject is measured by a signal from the distance measuring sensor 22 by a phase difference detection method, and the lens motor 14 is driven by a predetermined amount or stopped. The cam motor 11 and a lock motor 23 described later are driven and stopped. Further, a counter (not shown) is reset or starts counting, and pulse control is performed to rotate the stepping motors of the cam motor 11, the lens motor 14, and the lock motor 23 by a predetermined amount.

A signal processing circuit 19 includes an A / D conversion unit that converts an analog image signal from the image sensor 8 into digital image data, a timing generation circuit, an image processing unit, a memory control unit, and the like. Reference numeral 20 denotes a recording medium for storing captured images, which has a sufficient storage capacity for storing a predetermined number of images. Further, this recording medium is detachable and is constituted by a non-volatile memory such as a flash memory. Reference numeral 21 denotes a memory that stores constants, variables, programs, and the like for operation of the system control unit 14. The memory 21 stores information and numerical values that differ depending on the shooting conditions. In addition, various programs such as a program for performing imaging processing, a program for performing image processing, a program for recording the created image file data on the recording medium, and a program for reading the image file data from the recording medium 20 are recorded. The memory 21 also stores various programs such as an OS that implements and executes the multitask configuration of the program.

Reference numeral 22 denotes a distance measuring sensor which outputs distance information to the subject to the system control unit 18 by a phase difference method. Reference numeral 23 denotes a lock motor, here a stepping motor fixed to the main body. It rotates in the forward and reverse directions by pulse control from the system control unit 18, and the rotary ring 24 is reciprocally rotated by a predetermined angle through deceleration of a gear 23a that is rotatably fixed to the main body. The rotating ring 24 can be rotated smoothly and is supported by the main body with high accuracy in the optical axis direction. A part of the outer periphery has a gear portion (not shown) that meshes with the gear 23a, and the rotation is transmitted. In addition, three adjustment screws 24a are arranged in parallel with the optical axis direction at an equal angular interval of approximately 120 degrees, and like the adjustment screw 17, the plane of the object that abuts against the tip of the adjustment screw 24a due to its rotation. Gender can be determined. Here, the perpendicularity of the image sensor 8 with respect to the optical axis direction is adjusted. Instead of the lock motor 23 used for driving the rotating ring, a combination of an electromagnet and a spring can be used.

The three adjustment screws 24a are arranged corresponding to the three notches 8d of the holding plate 8a. Then, when the rotating ring 24 rotates clockwise (CW) as viewed from the direction of the lens 2 and stops, the phases of the recesses and protrusions of the notch 8d and the adjusting screw 24a match (unlock position), and the holding plate 8a. Can freely move back and forth through the rotating ring 24. This state is the unlocked state of FIG. When the rotating ring 24 rotates counterclockwise (CCW) when viewed from the lens 2 and stops, the holding plate 8a and the adjusting screw 24a partially overlap (lock position) when viewed from the optical axis direction, and the holding plate 8a. Cannot pass through the rotating ring 24. In this state, the flat portion of the overlapping portion of the tip of the adjustment screw 24 a and the holding plate 8 a comes into contact, and the image sensor 8 can be held and locked by the urging force of the spring 9. This state is the locked state of FIG. By adjusting the three adjustment screws 24a in advance so that the imaging element 8 forms a plane perpendicular to the optical axis, the imaging element 8 is locked with high accuracy.

The position where the imaging element 8 and the holding plate 8a are abutted and locked is in the middle of the movement range on the optical axis of the imaging element 8 and the holding plate 8a, and is the B position. This position is another one of the two scheduled image formation surfaces of the focus lens 13 in this embodiment. Thus, the planned imaging plane of the focus lens 13 is different between the first shooting mode and the second shooting mode. That is, the rotating ring 24 can lock or unlock the imaging element 8 and the holding plate 8a at a middle position in the movement range in the optical axis direction with a high level of flatness. . The rotating ring 24 and the adjusting screw 24a constitute first locking means.

On the other hand, in the image sensor movement range other than the two butted positions (A position, B position), the image sensor 8 and the holding plate 8a follow the plane formed by the three independent cams 11a. . Therefore, it is possible to adjust a so-called tilt angle with respect to the optical axis of the image pickup element 8 and the holding plate 8a by shifting the lift amount with different rotation angles of the three cams 11a.

(Description of operation of the first embodiment)
For the selection of the shooting mode, for example, for a subject that requires high-speed continuous shooting, the first shooting mode that is normal shooting is selected on the assumption that high speed is given priority over focus accuracy. On the other hand, when focus accuracy is required, the second shooting mode, which is focus bracket shooting in which the imaging element moving shooting is performed, is selected as the “high accuracy AF mode”. In focus bracket shooting, in addition to shooting on the planned imaging plane of the focus lens 13, shooting is also performed at a position shifted by a predetermined amount in the optical axis direction. The predetermined amount here is determined from, for example, a result of stacking a shift of a distance measurement result due to a manufacturing error of a camera distance measurement system or a shift of a driving position of the focus lens 13 due to a manufacturing error of a lens and a shift of a design value. The You can select how many frames you want to shoot before and after the planned imaging plane. Here, for example, if the design value is the planned imaging plane, then you can shoot one frame at the focus position and the previous focus position, respectively, for a total of 3 frames. , They are stored in the memory 21.

Next, the operation at the time of shooting will be described based on the flowcharts of FIGS. 8 and 9 with reference to the block diagrams of FIGS. 1 to 6, FIG. 7, and the layout of FIG. First, when SW1 is turned on by half-pressing the release button 3 in the power-on state (S102), photometry is performed by a photometric mechanism (not shown) and at the same time, the cam motor 11 is operated as a reset operation of the image sensor 8 to the A position. It reverses at low speed and moves the image sensor 8 to the lens side (S103). When the position sensor 12 is turned on and it is confirmed that the image sensor 8 and the holding plate 8a are at the standby position (position A) (S104), the pulse count to the cam motor 11 is reset once. Thereafter, the cam motor 11 rotates by a predetermined amount, stops after the cam 11a is completely separated from the holding plate 8a, and the reset operation of the image sensor 8 is completed (S105). Therefore, at the position A, the image sensor 8 and the holding plate 8a are not affected by the positions of the three cams 11a, but are accurately abutted by the spring 9 against the surface formed by the three adjusted adjustment screws 17. (See FIG. 2). When it is confirmed that the image sensor 8 and the holding plate 8a are present at the A position, the next transition is made. It is determined whether the setting by the mode switch 10 is currently in the first shooting mode or the second shooting mode (S106).

(Second shooting mode, bracket shooting)
When the second shooting mode, which is focus bracket shooting, is selected, that is, focus bracket shooting by moving the image sensor is performed for shooting that prioritizes focus accuracy. Accordingly, here, the lens drive is performed with the imaging element 8 and the holding plate 8a positioned at the above-described B position as the planned imaging plane. Distance measurement using the phase difference detection method is performed by the distance measurement sensor 22 and the system control unit 18 (S107). When a predetermined rotation amount is instructed to the lens motor 14, the moving unit 16 to which the focus lens 13 is attached moves forward by the rotation of the lead screw 15, and the lens is driven according to the distance of the subject with the B position as a planned imaging plane. Is executed (S108). This state is the state shown in FIG. 2, and the focus lens 13 has moved from the solid line position to the broken line position, assuming that the subject is at infinity.

Next, when the photographer intends to continue shooting, it is determined again that SW1 is turned on (S109). Subsequently, when SW2 is turned on by fully depressing the release button 3 (S110), the system control unit 18 corrects the cam motor 11 at high speed. Turn. Then, after a predetermined number of pulses, it is stopped and the imaging element 8 and the holding plate 8a are moved backward to reach the rear focus position, which is the position of the first frame of the moving shooting (S111). Here, the rear focus position is a position shifted from the B position, which is the planned imaging plane of the focusing lens 13, by 50 microns toward the subject. Next, in (S112), the mirror 5 is retracted from the imaging optical path (mirror up), the shutter blade 4a is opened by an exposure control device (not shown), and the electronic front curtain and electronic rear curtain operate to operate the first frame. Photographing is performed (S113). This state is the state of FIG.

Next, in (S114) of FIG. 9, the cam motor 11 is rotated forward at high speed, stopped after a predetermined number of pulses, and the image sensor 8 and the holding plate 8a are moved backward by the distance d1. This position is a position retracted by a predetermined amount from the B position, which is the planned imaging plane. Next, the lock motor 23 is rotated, the rotating ring 24 is rotated CCW, and stopped at a predetermined position. This is an operation of rotating from the unlock position to the lock position (S115). Here, the contact positions of the adjusting screw 24a and the holding plate 8a are opposed to each other at a predetermined interval. Next, when the image pickup device 8 and the holding plate 8a are moved to the lens side by reversing the cam motor 11 at a low speed, the adjusting screw 24a of the rotating ring 24 and the holding plate 8a eventually come into contact with each other and are pressed by the spring 9. An accurate plane is formed (S116). The cam motor 11 is rotated by a predetermined amount sufficient to move away from the position of the holding plate 8a in contact with the adjusting screw 24a and stops (S117). In other words, the holding plate 8a is abutted against the surface with high accuracy and locked at the B position, which is the planned imaging surface of the focus lens 13 (state shown in FIG. 5).

Next, the exposure control device opens the shutter blade 4a, and the electronic front curtain and the electronic rear curtain operate to take a second frame (S118). If there is no manufacturing error in the photographing at the B position, a just-focused image can be obtained. Therefore, here, the first locking unit operates to improve the image plane accuracy of the image sensor 8 for the second frame.

Next, the cam motor 11 is rotated forward at high speed, stopped after a predetermined number of pulses, and the image pickup device 8 and the holding plate 8a are moved backward by a distance d2 (S119). Next, the lock motor 23 is rotated, and the rotary ring 24 is rotated CW and stopped at a predetermined position. This is an operation of rotating from the locked position to the unlocked position. Thereby, the phase of the notch 8d of the holding plate 8a coincides with the phase of the adjustment screw 24a of the rotating ring 24. Accordingly, in the subsequent initial position return operation, when the image sensor 8 and the holding plate 8a move forward, the image sensor 8 and the holding plate 8a can smoothly pass through the rotating ring 24 (S120). When the image sensor 8 and the holding plate 8a reach the front focus position (S121), the exposure control device takes a third frame (S122). This position is a position moved 50 microns backward from the B position, which is the planned imaging surface, and is the rear end of the moving range of the imaging element 8 and the holding plate 8a of this embodiment. This state is the state of FIG.

Next, in (S123), the mirror 5 returns to the finder observation position (mirror down). Then, in order to put the image sensor 8 and the holding plate 8a into the next photographing standby state, the cam motor 11 is reversely rotated as the returning operation to the A position, and the image sensor 8 and the holding plate 8a are advanced (S124). Eventually, when the image sensor 8 and the holding plate 8a reach the A position, the rotation of the cam motor 11 is stopped by the signal determination from the position sensor 12 (S125) (S126). Thereafter, if the half-press of the release button 3 is not confirmed in (S127) (SW1: OFF), the photographing is finished and the state returns to the state of FIG. 2 (S128). If the photographer intends to perform continuous shooting, SW1 remains on, and the process returns to (S102) to perform continuous shooting.

Next, the image with the highest evaluation value is selected as the best focus image among the three images with different shooting positions recorded in the memory 21 by the above imaging operation, and is recorded on the recording medium 20, and the other images are stored in the memory. Delete from 21. As the image evaluation method, known contrast detection or the like is used. For example, the contrast of the image in the same area as the focus detection area selected at the time of detecting the phase difference AF is obtained and compared for each image. In this way, only an image in the best focus state can be recorded and saved for each photographing.

By the above operation, in addition to the autofocus operation by the movement of the focus lens 13, the image pickup device 8 is substantially retracted sequentially. As a result, here, a total of three images were shot, that is, a shooting frame at the B position, which is the planned imaging plane of the focus lens 13, and shooting frames at two positions before and after that. Therefore, even if there is an unexpected imaging plane shift due to manufacturing variations or errors in the photographic lens 2 or camera, compared to images taken with a conventional fixed imaging device in the three shots. Thus, it is possible to obtain an image with good focus accuracy.

Further, in focus bracket shooting in the second shooting mode, the image sensor 8 and the holding plate 8a are precisely adjusted by the adjusting screw 24a at the B position which is an intermediate position of the image sensor moving range with the highest probability of focusing. It is in a state of being hit against the surface. Therefore, after adjustment to the conventional main body, it has surface accuracy equivalent to that of the fixed image sensor. As a result, the imaging apparatus has the same focusing accuracy as the conventional one while having the imaging element moving mechanism. All of these movements to the three locations are performed by the substantial retreat of the image sensor 8 and the holding plate 8a (although there is a slight reverse movement when brought to the B position), so that the movement time is shortened at a high speed. Can be driven.

(First shooting mode, fixed position shooting)
Next, an operation in the case of the first shooting mode in which the setting of the main body 1 is the normal shooting without moving the image sensor will be described. This mode is suitable for high-speed continuous shooting. When the first shooting mode is selected in (S106), the planned imaging plane of the focus lens 13 is at the A position in the first shooting mode. Therefore, the system control unit 18 selects to perform a calculation based on the A position for the numerical value related to the driving amount calculation of the focus lens 13 (S129). In the state of FIG. 2, phase difference AF detection is performed (S130), and based on the calculation determined in (S129), the focus lens 13 is driven so that the position A is a planned imaging plane (S131). Specifically, for the distance measurement information of the subject from the distance measurement sensor 22, when the system control unit 18 calculates the feed pulse of the lens motor 14, the feed pulse when the planned imaging plane is set to the A position is calculated. To do. Thereafter, the mirror 5 is retracted from the photographing optical path (mirror up) (S132), and the subject image is thereby formed on the imaging surface of the image sensor 8, so that the exposure control device performs photographing (S133). At this time, the image sensor 8 and the holding plate 8 a are abutted against the abutting surface that is precisely adjusted by the adjusting screw 17.

Next, the mirror 5 is returned to the finder observation position, the mirror is lowered (S134), and if the half-press of the release button 3 is not confirmed (SW1: OFF), the imaging is finished through (S135) (S136). ). If the photographer intends to perform continuous shooting, SW1 remains on, and the process returns to (S102) to perform continuous shooting.

The positional relationship in the optical axis direction of the elements of the above-described embodiment will be described with reference to the table and FIG. Here, only the photographing lens 2, the main body 1, the focus lens 13, and the image sensor 8 are shown for easy understanding. In the first shooting mode, since the image pickup device 8 is abutting fixed shooting at the A position, for example, when the subject is at the closest position, the focus lens 13 moves to (4) with the A position as the planned imaging plane. Done. Similarly, when the subject is at infinity, the focus lens 13 is moved to the position (2) for shooting.

In the second shooting mode, the image pickup device 8 moves and shoots at a total of three positions before and after the B position as the center. For example, when the subject is at the closest position, the focus lens 13 sets the B position as the planned image plane. Move to (3). Thereafter, the image sensor 8 moves to a total of three locations before and after the image. Among them, at the B position, the image pickup device 8 and the holding plate 8a are abutted and fixed by the locking means and photographed. Similarly, when the subject is at infinity, the focus lens 13 moves to (1). Thereafter, the image sensor 8 moves to a total of three locations before and after the image. Among them, at the B position, the image pickup device 8 and the holding plate 8a are abutted and fixed by the locking means and photographed. That is, in the first photographing mode, lens driving is performed in the range of (2) to (4), and in the second photographing mode, in accordance with the phase difference detection method in the range of (1) to (3). Lens driving is performed.

In this way, the planned image planes of the focus lens are different in the first shooting mode and the second shooting mode. In other words, the scheduled imaging plane in the first shooting mode is provided closer to the subject than the rear focus side shooting position in the second shooting mode. Alternatively, when moving from the rear to the subject side by changing the direction of movement of the image sensor, the planned imaging plane in the first shooting mode is behind the front focus side shooting position in the second shooting mode (opposite to the subject). Side). In the second shooting mode, in the middle of the moving range of the image sensor, the first lock means including the adjusting screw 24a locks the image sensor.

(Effect of Example 1)
As described above, there are two shooting modes of normal shooting (image sensor fixed shooting) and bracket shooting (moving shooting), and the lens positions (or focal planes) are different in each mode in advance. Therefore, when switching between imaging device fixed imaging and moving imaging, and bracket imaging, images are taken while sequentially proceeding in substantially one direction, so that the rapid reversal of imaging device movement is not substantially included. Thus, useless movement of the image sensor is suppressed, and it is possible to configure an image pickup apparatus that operates smoothly. Further, in the first photographing mode, since the image sensor is brought into contact with the standby position established by the adjustment mechanism constituted by the adjustment screw 17, the surface accuracy equivalent to that of the image sensor fixed to the main body is obtained. ing.

In addition, as compared with a device that does not have an image sensor moving mechanism, the imaging sequence is also provided with a condition determination part. As a result, the imaging sequence has a high speed equivalent to that of a conventional camera while having an image sensor moving mechanism. The imaging apparatus has a mode. In addition, the movable abutting member is mechanically locked at an intermediate position within the moving range of the image sensor to improve the surface accuracy of the image sensor. Therefore, in focus bracket shooting, the intermediate position around the planned image plane with the highest focus ratio The imaging surface accuracy of the imaging device is improved.

As a result, even if there is an image sensor moving mechanism, it is possible to mechanically lock the image sensor in the middle of the image sensor moving range by an advanceable / retractable locking means. Since the image surface accuracy can be improved by abutting against a high abutment surface, and the abutment surface of the locking means can be adjusted, the imaging surface accuracy is reliably high at any position in the image sensor movement range. An image can be obtained.

(Example 2)
In the first embodiment, the holding plate 8a to which the image pickup device 8 is fixed is locked and unlocked only at an intermediate position of the focus bracket by the rotation of the rotating ring 24 serving as a locking unit. However, the locking means is not limited to this method, and the locking position is not limited to the intermediate position.

In the second embodiment, all the stop positions (here, three positions) of a plurality of frames to be photographed in the focus bracket method are locked, and the lock means is slid from the outer periphery and locked. Since the other elements are basically the same as those in the first embodiment, the same numbers as those in the first embodiment are given. Therefore, different portions of the locking means will be mainly described.

(Configuration of Example 2)
A second embodiment of the present invention will be described with reference to FIGS. FIG. 11 is a cross-sectional view of the main part of the image sensor moving mechanism of the image pickup apparatus, and shows one movement position (front focus position) of the image sensor 108 and the holding plate 108a. FIG. 12 is a front view of the main part in the state of FIG. The image sensor 108 is fixed to the holding plate 108a in a completely parallel manner, supported by the guide shaft 7 fixed to the main body, and advances and retreats in the optical axis direction (here, the left and right direction in the drawing).

The circular holding plate 108a integrally attached to the image sensor 108 is pressed by the three springs 9 from the back side. A lock member 124 is slidably movable from the outside toward the optical axis with respect to a main body (not shown), and is provided with three at regular angular intervals of about 120 degrees around the optical axis. The drive source of the lock member 124 is a lock motor (not shown), and slide-drives the lock member 124 supported by a rail or the like by a rack and pinion method or the like.

As shown in FIG. 11, one lock member 124 shifts three abutting surfaces 124 a, 124 b, and 124 c that are abutted from the direction opposite to the lens with respect to the optical axis direction by a predetermined amount in the optical axis direction. I have. Here, the abutting surface for establishing the focus imaging plane of the focus lens is defined as an abutting surface 124b, and the abutting surfaces 124b and 124c shifted by a predetermined amount are used as the abutting surfaces for establishing the front and rear focus positions. Is provided. That is, the abutting surface 124a as the rear focus position and the abutting surface 124c as the front focus position. The lock member 124 is attached with high accuracy without play in the optical axis direction. When the holding plate 108a is abutted against the abutting surfaces of the three lock members 124, a plane perpendicular to the optical axis is formed by the three points. When the image sensor 108 and the holding plate 108a pass, the lock member 124 is retracted outward from the moving region and unlocked. Others are the same as the first embodiment.

(Description of operation of the second embodiment)
The operation will be described with reference to the flowchart of FIG. Here, since the first shooting mode is the same as that of the first embodiment, only the second shooting mode of the bracket shooting mode will be described. First, when SW1 is turned on by half-pressing the release button 3 in the power-on state (S202), photometry is performed by the photometry mechanism, and at the same time, the lock motor is rotated and the lock member 124 is retracted from the optical axis to the outside. Lock (S203). (S204) to (S207) are the same as (S103) to (S106) in FIG.

(Second shooting mode, bracket shooting)
When the second shooting mode that is focus bracket shooting is selected, the process up to (S209) is the same as (S108) in FIG. Next, when the photographer intends to continue shooting, it is determined again that SW1 is turned on (S210). Subsequently, when SW2 is turned on by fully depressing the release button 3 (S211), three switches are displayed in (S212) in FIG. The lock member 124 moves from the lock position to the unlock position. If it is already unlocked, the unlocking is confirmed by performing a process such as reversing a lock motor (not shown) by a predetermined pulse, for example. Next, the image sensor 108 and the holding plate 108a retract from the position in the first imaging mode to the last position in the image sensor movement range (S213).

When the image sensor 108 and the holding plate 108a reach the rearmost position, the lock member 124 slides from the outer periphery to the optical axis direction to reach the lock position (S214). Next, when the cam motor 11 rotates in the reverse direction and the image sensor 108 and the holding plate 108a move forward, the spring 9 is pressed against the three abutting surfaces 124c of the lock member 124 from the rear. Then, the image pickup device 108 and the holding plate 108a are held with high accuracy following the plane formed by the three abutting surfaces 124c (S216). This is a state at the front focus position (Ff) behind the planned imaging plane (Jf) of the focus lens in FIG. In this state, the mirror is raised (S217), and photographing at the front focus position is performed (S218).

Next, the three lock members 124 again move from the lock position to the unlock position (S219). The image sensor 108 and the holding plate 108a advance from the front focus position to the front of the planned imaging surface (S220). When the image sensor 108 and the holding plate 108a pass through the abutting portion 124c of the lock member 124, the lock member 124 slides from the outer periphery to the optical axis direction and reaches the lock position (S221). Next, when the cam motor 11 rotates in the reverse direction (S222) and the image sensor 108 and the holding plate 108a move forward, they are pressed against the three abutting surfaces 124b of the lock member 124 by the spring 9 from the rear. Then, it falls down along the plane formed by them and is held with good accuracy (S223). In this way, the second frame on the planned imaging plane is shot in the state where it is on the planned imaging plane (Jf) of the focus lens (S225).

Next, the three lock members 124 again move from the lock position to the unlock position (S226). Next, the image sensor 108 and the holding plate 108a advance from the planned image plane position to the position before the rear focus position (S227). When the image sensor 108 and the holding plate 108a pass through the abutting portion 124b of the lock member 124, the lock member 124 slides from the outer periphery in the optical axis direction to reach the lock position (S228). Next, when the cam motor 11 rotates in the reverse direction (S229) and the image sensor 108 and the holding plate 108a move forward, they are pressed against the three abutting surfaces 124a of the lock member 124 by the spring 9 from the rear. Then, it falls down along the plane formed by them and is held with high accuracy (S230). Thus, the third frame is photographed at the rear focus position in the state where the focus lens is at the rear focus position (Rf) (S231). Operations from (S232) to (S237) are the same as those in the first embodiment. This completes the shooting.

(Effect of Example 2)
In the present embodiment, in addition to the effects of the first embodiment, the image pickup device is used for each of the rear focus side shooting, scheduled imaging plane shooting, and front focus side shooting in the focus bracket shooting in the second shooting mode. It is possible to hold and shoot. This is performed by the first locking means that slides from the outer peripheral side toward the optical axis. Here, since the locking member that performs the abutting has three abutting surfaces of the rear focusing side imaging position, the planned imaging plane imaging position, and the front focusing side imaging position, the abutting imaging is performed for all bracket imaging. Is possible. Therefore, since the imaging surface accuracy of the imaging element is high in all shootings, all the shot images can be made good images with no blurring. Also in this case, when switching between fixed shooting and moving shooting, and during bracket shooting, the moving direction of the image sensor is substantially constant and there is substantially no reversing operation, so that smooth shooting without waste can be performed.

(Example 3)
In the above-described embodiment, a mechanism for moving and holding the image pickup device by the cam motor and the spring has been shown as an example of the focus bracket method using the phase difference AF as a detection system. On the other hand, in the third embodiment, an electromagnetic drive system using a coil and a permanent magnet and a mechanism for moving and holding by a spring are adopted. Basically, other elements are the same as those in the first embodiment.

(Configuration of Example 3)
The configuration of the present embodiment will be described with reference to FIGS. FIG. 15 is a partial cross-sectional view of the image pickup apparatus according to the third embodiment. FIG. 15A shows a state in which the image pickup device 208 and the holding plate 208a are held and fixed by the first locking means. FIG. 18B shows a state in which the image pickup device 208 and the holding plate 208a are moved forward by the pressing of the spring 9 by reducing the energization amount of the coil 211 by the lock means being unlocked. FIG. 16 is a front view of the main part of the imaging apparatus, and FIGS. 17 and 18 are flowcharts of operations.

In this embodiment, the system control unit 18 which is the control means of FIG. 7 includes a phase difference AF function and an exposure control means. In the block diagram of FIG. 7, in this embodiment, instead of the cam motor 11, a coil 211 and a hall element 230 are connected to the system control unit 18. The system control unit 18 receives a signal from the position sensor 12 and determines whether or not the holding plate 208a is currently in the standby position (position A). Further, based on the output of the hall element 230, it is determined which position in the moving range of the image sensor 208 the holding plate 208a is currently in, and the activation timing of the lock motor 23 is controlled. The distance to the subject is measured by a signal from the distance measuring sensor 22 by the phase difference detection method, and the amount of current supplied to the coil 211 is controlled to move and stop the image sensor 208.

Further, the system control unit 18 resets a counter (not shown) or starts counting, and performs pulse control for rotating the stepping motors of the lens motor 14 and the lock motor 23 by a predetermined amount. Further, the shift amount of the image sensor in bracket shooting can be changed by information from an AE detection device (not shown). Here, the shift amount is assumed to be 50 microns both in the front and rear directions with respect to the planned imaging plane, but it can be changed according to the set aperture value, or can be changed in the front and back directions and equally.

In FIG. 15, the image sensor 208 is fixed to the holding plate 208a in a completely parallel manner, supported by a guide shaft 7 fixed to the main body, and advances and retreats in the optical axis direction. The circular holding plate 208a integrally attached to the image sensor 208 is pressed by the three springs 9 from the back side. Reference numeral 211 denotes a coil in which a coated conductive wire is wound. The coil 211 is arranged and fixed to the shutter base plate 4 at three positions around the image sensor 8 at equal angular intervals of 120 degrees, and the direction of the electromagnetic force changes depending on the direction of the current flowing to the conducting wire. The magnitude of the electromagnetic force changes depending on the amount.

Reference numeral 220 denotes a permanent magnet, which is magnetized to have two poles in the plate thickness direction at positions facing the coil 211, and is fixed to the holding plate 208 a of the image sensor 208. The coil 211, the permanent magnet 220, the guide shaft 7, and the spring 9 constitute first moving means. Reference numeral 224 denotes a locking member as a first locking means, which is slidably movable from the outside toward the optical axis with respect to a main body (not shown), and is provided at three equal angular intervals of about 120 degrees around the optical axis. I have it. The drive source of the lock member 224 is the same as the drive source described in the second embodiment. Reference numeral 224a denotes a friction member whose thickness changes depending on pressure. The friction member 224a is fixed to the end surface of the lock member 224, and is a high friction member such as rubber or elastomer that can reliably hold the holding plate 208a of the image sensor 208 even with a small pressure. Reference numeral 230 denotes detection means such as a Hall element fixed at three positions of the main body, and each is arranged corresponding to the three permanent magnets 220. Therefore, the magnetic force of the permanent magnet 220 can be detected, and the position of the image sensor 208 and the holding plate 208a in the optical axis direction can be calculated by the system control unit 18 based on the change in output depending on the distance. The current state of the image sensor 208 and the holding plate 208a The position of is detected.

In FIG. 15, the electromagnetic force generated in the optical axis direction changes in accordance with the amount of current flowing through the coil 211, so that a repulsive force is generated between the surface magnetic fluxes of the opposing permanent magnet 220 and the spring 9. It becomes possible to change the spring balance. Since the image pickup device 8 and the holding plate 8a are supported by the two guide shafts 7 so as to be movable in the optical axis direction, the optical axes of the image pickup device 208 and the holding plate 208a according to the direction and amount of current of the coil 211. It is possible to control the movement of the direction. Further, when the energization amount is changed with time, the moving speed of the image sensor 208 and the holding plate 208a in the optical axis direction changes. In addition, it is possible to adjust the electromagnetic force at three locations by controlling the current independently for each of the three coils, and to change the perpendicularity of the image sensor 208 and the holding plate 208a with respect to the optical axis. is there.

Here, for ease of explanation, energizing the coil 211 and the permanent magnet 220 so that the imaging element 208 and the holding plate 208a are retracted by generating an electromagnetic force in a direction in which the coils 211 and the permanent magnet 220 repel each other is referred to as positive energization. . Accordingly, the system control unit 18 controls the direction in which the coil 211 is energized and the speed at which the energization amount is changed, so that the image sensor 208 and the holding plate 208a are advanced or retracted to desired positions, and the moving speed is further controlled. be able to.

(Description of operation of the third embodiment)
Next, an operation when photographing is described based on the flowchart of FIG. First, when SW1 is turned on by half-pressing the release button 3 in the power-on state (S302), photometry is performed by the photometry mechanism, and at the same time, the lock motor is rotated and the lock member 224 is retracted from the optical axis to the outside. Lock (S303). Next, the image sensor 208 is reset to the A position. When the coil 211 is in a non-energized state, only the urging force of the spring 9 is applied to the image pickup device 208 and the holding plate 208a, so that it should normally be in contact with the abutting portion 17a. However, if the image pickup device 208 and the holding plate 208a have moved as a reset operation, reverse energization is performed on the coil 211 (S304), and abutment is made using the adsorption force of the coil 211 in addition to the biasing force of the spring 9. Promptly. Eventually, the position sensor 12 is turned on, and it is confirmed that the image sensor 208 and the holding plate 208a are at the standby position (position A) (S305), and the power supply to the coil 211 is turned off (S306).

From the above, the image sensor 208 and the holding plate 208a are gently abutted by the spring 9 against the surface formed by the adjusted three adjustment screws 17. Therefore, it is held at a predetermined angle with respect to the optical axis. When it is confirmed that the image sensor 208 and the holding plate 208a are at the A position, the energization of the coil 211 is stopped and the movement of the image sensor is stopped. Thus, at the position A, the image sensor 208 and the holding plate 208a are pressed against the surface formed by the adjusted three adjustment screws 17 with high accuracy by the spring 9. Next, it is determined whether the setting by the mode switch 10 is the first shooting mode or the second shooting mode (S307).

(Second shooting mode, bracket shooting)
When the second shooting mode is selected, here, focus lens driving is performed with the B position as the planned imaging plane at the position of the image sensor 208. When the distance measurement sensor 22 and the system control unit 18 perform phase difference detection type distance measurement (S308) and a predetermined rotation amount is instructed to the lens motor 14, the distance of the subject is set with the position B as the planned imaging plane. The lens drive corresponding to is executed (S309).

Next, when the photographer intends to continue shooting, it is determined again that SW1 is turned on (S310). Subsequently, when SW2 is turned on by fully depressing the release button 3 (S311), the system control unit 18 applies positive current to the coil 211. Do. Then, the energization amount is gradually increased, and the imaging element 208 and the holding plate 208a are moved backward to go to the rear focus position which is the first frame of the moving shooting (S312). The current output of the hall element 230 and the hall element output that is the target value of the rear focus position stored in the system control unit 18 are compared to determine that the target position has been reached (S313). The increase in the energization amount 211 is stopped (S314). As shown in FIG. 18, the three lock members 224 simultaneously slide from the outer periphery in the optical axis direction to reach the lock position, and the friction member 224a holds the outer periphery of the holding plate 208a at three locations (S315). At this time, since the thickness of each of the three friction members 224a changes, even if there is an assembly error with respect to the optical axis between the support mechanism by the guide shaft 7 and the lock member, it is absorbed and the imaging element 208 and the holding plate 208a are absorbed. There is no loss of flatness. Further, since the holding plate 208a is securely held without shifting, it is possible to save energy by turning off the energization of the coil 211 in this state.

Next, in (S316) of FIG. 18, the mirror 5 is retracted from the photographing optical path (mirror up), the shutter blade 4a is opened by the exposure control device, the electronic front curtain and the electronic rear curtain operate, and the rear focus. The first frame of the state is photographed (S317). This is the state of FIG. Next, the lock member 224 is unlocked again (S318), the coil 211 is positively energized, and the energizing amount is gradually increased to retract the image pickup device 208 and the holding plate 208a, which is the planned imaging plane. Heading to position B (S319). Here, the position B, which is the planned imaging plane, is the planned imaging plane of the focusing lens 13 that has already moved, and is a position where a just-focused image can be obtained if there are no manufacturing errors. The current output of the Hall element 230 is compared with the Hall element output that is the target value of the B position, which is the planned imaging plane stored in the system control unit 18, and is determined to be equal, so that it is determined that the target position has been reached. (S320), and the increase in the energization amount of the coil 211 is stopped (S321).

At the same time, the three lock members 224 slide from the outer periphery in the optical axis direction to reach the lock position, and the friction member 224a holds the outer periphery of the holding plate 208a from three locations (S322). At this time, since the thickness of each of the three friction members 224a changes, even if there is an assembly error with respect to the optical axis between the support mechanism by the guide shaft 7 and the lock member, it is absorbed and the imaging element 208 and the holding plate 208a There is no loss of flatness. Further, since the holding plate 208a is securely held without shifting, it is possible to save energy by turning off the energization of the coil 211 in this state. The exposure control device operates the electronic front curtain and the electronic rear curtain to take a second frame on the scheduled image plane (S323).

Next, the lock member 224 is unlocked again (S324), the coil 211 is positively energized, the energization amount is gradually increased, and the image sensor 208 and the holding plate 208a are moved backward to the front focus position ( S325). Here, the front focus position is a position that is retracted by a predetermined amount from the planned imaging plane of the focusing lens 13 that has already moved, and is a position from which a front focus image can be obtained if there is no manufacturing error or the like. The current output of the Hall element 230 and the Hall element output that is the target value of the previous focus position stored in the system control unit 18 are compared and determined to be equal to each other to determine that the target position has been reached (S326). The increase in the energization amount of the coil 211 is stopped (S327).

At the same time, the three lock members 224 slide in the optical axis direction from the outer periphery to reach the lock position, and the friction member 224a holds the outer periphery of the holding plate 208a from three locations (S328). The locked state at this time is also the same as the above-described locked state. The exposure control device operates the electronic front curtain and the electronic rear curtain to take the third frame at the front focus position (S329).

Next, in (S330), the mirror 5 returns to the viewfinder observation position (mirror down), and the lock member 224 is unlocked (S331). Then, the imaging element 208 and the holding plate 208a are moved back to the A position so that the imaging device 208 and the holding plate 208a are moved back to the A position. (S332). Eventually, when the image sensor 208 and the holding plate 208a reach the A position, the energization of the coil 211 is stopped by the determination of the signal from the position sensor 12 (S333) (S334). Thereafter, if it is not confirmed that the release button 3 is half-pressed (SW1: OFF), the shooting is finished through (S335) (S336). If the photographer intends to perform continuous shooting, SW1 remains on and the process returns to (S302) in FIG. 17 to perform continuous shooting. Here, the position of the image sensor is shifted by a predetermined amount as bracket shooting, but the shift amount can be appropriately changed according to information from the AE apparatus. For example, when the set aperture value of the lens is small and the depth of field is shallow, the effect of a large focus bracket can be obtained by setting the shift amount small.

Next, the image with the highest evaluation value is selected as the best focus image among the three images with different shooting positions recorded in the memory 21 by the above imaging operation, and is recorded on the recording medium 20, and the other images are stored in the memory 21. Erase from This is as described in the first embodiment.

(First shooting mode, fixed position shooting)
Operations (S337) to (S344) in the first photographing mode are the same as the operations (S129) to (S136) in the first embodiment. Even in the first imaging mode, the surface accuracy is the same as that of a fixed image sensor after adjustment to the conventional main body.

(Effect of Example 3)
Here, in addition to the effects of the first embodiment, the position where the image pickup device is locked is made stepless, so that the mechanical lock can be performed after the shift amount in the optical axis direction for bracket shooting is freely selected. That is, it is possible to select a shift amount according to a change in the depth of field in terms of focal length, brightness, etc., and the probability that a bracketed image will be just focused is improved. Also in this case, the moving direction of the image sensor is fixed when switching between fixed shooting and moving shooting and during bracket shooting, and since there is no reversing operation, smooth shooting without waste can be performed.

Example 4
In the above embodiment, the present invention has been described by taking the focus bracket system using the phase difference AF as a detection system as an example. In the fourth embodiment, a mechanism for realizing high-precision AF using an imaging element capable of contrast AF in addition to phase difference AF will be described. Basically, other elements are the same as those in the first embodiment.

(Configuration of Example 4)
The configuration of this embodiment will be described with reference to FIGS. FIG. 19 is a partial cross-sectional view of the image pickup apparatus according to the fourth embodiment of the present invention, and shows a state where the image pickup device 308 and the holding plate 308a are held and fixed by a lock member 324 serving as a second lock unit. FIG. 20 shows a state of the image sensor 308 and the holding plate 308a during the wobbling operation when the lock member 324 is unlocked. FIG. 21 is a flowchart of the operation.

In the present embodiment, the system control unit 18 as a control means includes a phase difference AF function means, a contrast AF processing function means, and an exposure control means. The system control unit 18 includes a microcomputer unit including a CPU, and executes a built-in program. In addition, a sequence such as photometry and distance measurement is started by a signal from the release button 3. Further, the distance to the subject is measured by a signal from the distance measuring sensor 22 by a phase difference detection method, and the focus lens 13 is moved at high speed. Further, the modulation waveform signal is input to the coil 211 to perform the wobbling operation of the image sensor 308. Further, a counter (not shown) is reset and counting is started, and pulse control is performed to rotate the stepping motors of the lens motor 14 and the lock motor 23 by a predetermined amount.

In FIG. 19, an image sensor 308 converts an image projected on the imaging surface into an electrical signal. Also, a so-called contrast AF detection function is provided using the image signal. That is, when a modulation waveform signal of several hertz to several tens of hertz is input to the coil 211, the electromagnetic force changes minutely, and the imaging element 308 and the holding plate 308a are moved along the optical axis by the pressing force of the permanent magnet 220 and the spring 9. A small amount reciprocates in the direction. At this time, an image signal of the distance measurement target area of the image sensor is acquired, and an evaluation is made as to whether or not the contrast of the image is improved when the image signal is moved in a small amount in the front or rear direction. In other words, when the current position of the focus lens that has been positioned at high speed is truly a just-focused position or shifted, it is possible to recognize whether the focus lens is in the front focus state or the rear focus state.

The image pickup device 308 is fixed to the holding plate 308a completely in parallel, and is supported by the guide shaft 7 fixed to the main body so as to advance and retreat in the optical axis direction. The image sensor 308 has a function of an electronic front curtain as an electronic shutter that starts image signal capturing and an electronic rear curtain that stops capturing. The circular holding plate 308a integrally attached to the image sensor 308 is pressed by the three springs 9 from the back side. Reference numeral 308e denotes a convex portion provided on the end face of the holding plate 308a. Reference numeral 324 denotes a lock member as a second lock means, which is slidably movable from the outside toward the optical axis with respect to the main body, and is provided with three at equal angular intervals of about 120 degrees around the optical axis. . A drive source of the lock member 324 slides and drives the lock member 324 supported by a rail or the like by a rack and pinion method or the like with a lock motor (not shown). Reference numeral 324a denotes a lock portion, which is a recess into which the convex portion 308e of the holding plate 308a fits, and the perpendicularity of the holding plate 308a with respect to the optical axis direction is determined by the lock portions 324a of the three lock members 324 configured with high accuracy with respect to the optical axis. Is done.

(Description of the operation of the fourth embodiment)
Next, an operation when photographing is described based on the flowchart of FIG. Here, the case where the wobbling operation is performed in the first imaging mode in which the planned imaging plane of the focus lens 13 is at the A position will be described. However, the wobbling operation is performed in the second imaging mode in which the planned imaging plane is at the B position. You can also. First, when SW1 is turned on by half-pressing the release button 3 in the power-on state (S402), photometry is performed by the photometry mechanism, and at the same time, the ranging system executes phase difference AF detection (S403), and the focus lens 13 is moved. It moves to a predetermined position at high speed (S404). Next, the lock motor rotates, and the lock member 324 is retracted outward from the optical axis and unlocked (S405).

Next, the image sensor 308 starts wobbling at 10 hertz (S406). That is, the image sensor 308 vibrates with a stroke of 10 microns before and after in the optical axis direction, converts the image signal imaged on the imaging surface in synchronism with the back and forth operation, and performs contrast evaluation. As a result, the front focus, the rear focus, and the just focus at the current position of the focus lens 13 are determined depending on whether a higher contrast is obtained when moving in the forward or backward direction. Thereby, it is possible to know the moving direction when the focus lens 13 is finely adjusted next time. In other words, the focus lens 13 is slightly moved forward in the current focus state. If it is in the rear focus state, it is moved backward. If the focus is just, fine adjustment is not performed (S407).

If the direction of fine adjustment can be known, it is stored in the memory and the wobbling operation is stopped (S408). At the same time, the lock motor rotates to move the three lock members 324 to the lock position, and the convex portions 308e of the holding plate 308a fall into the lock portions 324a to hold and fix the image sensor 308 (S409). This is the state of FIG. Therefore, the image sensor 308 and the holding plate 308a are fixed to a surface formed by the three lock portions 324a configured with high accuracy. Accordingly, the image sensor 308 is held at a predetermined angle with respect to the optical axis.

Next, according to the intention of the photographer to continue photographing, it is determined again whether SW1 is on (S410). Subsequently, when SW2 is turned on by fully depressing the release button 3 (S411), the system control unit 18 again moves the focus lens 13 by a minute amount in the direction of displacement recognized in (S407) (S412). Here, for example, a slight rear pin is assumed. At the same time, the image sensor 308 performs contrast evaluation again in synchronization with the movement of the focus lens 13 in (S412) (S413). In the evaluation, when the contrast is improved as the focus lens 13 is finely moved, the focus lens 13 is subsequently finely moved in the same direction. When it is recognized that the contrast value has reached its peak and has started to fall, the focus lens 13 is stopped (S414).

The AF operation is thus completed, and then the mirror 5 is retracted from the photographing optical path (mirror up) in (S415), the shutter blade 4a is opened by the exposure control device, and the electronic front curtain and electronic rear curtain operate. Then, photographing is performed (S416). Next, in (S417), the mirror 5 returns to the finder observation position (mirror down). After that, if the release button 3 is not half-pressed (SW1: OFF), the imaging is finished through (S418). (S419). If the photographer intends to perform continuous shooting, SW1 remains on, and the process returns to (S402) to perform continuous shooting.

(Effect of Example 4)
As described above, in the present embodiment, the imaging element 308 to be wobbled is configured to be locked by the second locking means only during shooting and to increase the imaging surface accuracy of the imaging element. As a result, while having an AF system for wobbling, it is an imaging device that can obtain an image with less one-side blur equivalent to the conventional one. Also in this case, the moving direction of the image sensor is fixed at the time of switching between fixed shooting and moving shooting and during bracket shooting, and the reversing operation is suppressed, so that smooth shooting with less waste can be performed. In other words, the present embodiment has a second locking means that locks when the imaging device stops wobbling, and the control means resumes wobbling in synchronization with the unlocking of the locking means. Control. As a result, even in the wobbling AF system, it is possible to reliably hold and fix the image sensor during image capturing, and an image with high imaging surface accuracy can be obtained. In this embodiment, an autofocus system for a single-lens reflex camera that performs wobbling has been described. However, this configuration can also be applied to other digital video cameras, surveillance cameras, web cameras, cameras mounted on mobile phones, and the like.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary. Each of the embodiments described above can be applied to an imaging device such as a lens-integrated camera, a camera body, and a lens device attached to the camera.

2 .. Photography lens (optical means) 8.. Image sensor 11.. Cam motor (first moving means) 13. Focus lens 14.. Lens motor (second moving means) 18. Part (control means), 22 ..focus detection means

Claims (10)

An image pickup element on which a subject light flux that has passed through the optical means is imaged, a focus detection means, a first moving means for moving the image pickup element in the optical axis direction, and the image pickup element based on a signal from the focus detection means A focus lens that forms an image of the subject luminous flux on the imaging surface, a second moving unit that moves the focus lens in the optical axis direction, and a control unit,
The control means executes shooting by switching the shooting mode between a first shooting mode for shooting without moving the image sensor and a second shooting mode for shooting a plurality of frames by moving the image sensor. Has function,
The imaging apparatus, wherein the second imaging mode has a scheduled imaging plane that is different in the optical axis direction from the scheduled imaging plane of the first imaging mode. 2. The image pickup apparatus according to claim 1, wherein in the second shooting mode, the focus lens is controlled such that an intermediate position of a moving range of the image pickup device is a planned image formation plane. A first locking means for determining a plane of the imaging surface of the imaging element in the second imaging mode;
The first locking means is between a lock position that determines a plane of an image pickup surface of the image pickup element by abutting against the image pickup element or its holding plate, and an unlock position that allows the image pickup element to move in the optical axis direction. The imaging apparatus according to claim 1, wherein the imaging apparatus is movable. 4. The imaging apparatus according to claim 3, wherein in the second imaging mode, the first locking unit determines the perpendicularity of the imaging element with respect to the optical axis, not the first moving unit. 5. . 5. The image pickup apparatus according to claim 3, wherein the first lock unit is capable of adjusting a position where the first lock unit hits the image pickup element or a holding plate thereof. Means for wobbling the image sensor; and a second lock for locking the position of the image sensor when the image sensor stops wobbling and unlocking the image sensor when the image sensor starts wobbling And further comprising means
6. The imaging apparatus according to claim 1, wherein the control unit causes the imaging element to wobble so as to resume wobbling in synchronization with the unlocking of the second locking unit. . The imaging apparatus according to claim 1, wherein the first lock unit rotates coaxially with the optical axis and moves between a lock position and an unlock position. The first or second locking means slides so as to approach or move away from the optical axis, and moves between a locked position and an unlocked position. The imaging apparatus of Claim 1. The imaging apparatus according to any one of claims 1 to 8, wherein the first and second locking means are driven by a motor or an electromagnet. The control means evaluates the captured images of the plurality of frames in a distance measurement area of the focus detection means, and selects an image having a high evaluation value from the plurality of images based on a result of the image evaluation. The imaging device according to any one of claims 1 to 9.

Images