JP2013016945A - Camera system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera system in which image skip can be corrected accurately during focus inversion drive, without requiring high speed sample detection of a motion vector.SOLUTION: When performing inverse drive of a focus lens being driven at a first driving speed in a first direction to a second direction opposite from the first direction during moving image pick-up, focus drive control means (207) drives the focus lens at a second driving speed slower than the first driving speed. Motion vector detection means (113) detects a motion vector from an image sensor, and correction drive control means (205) drives a shake correction optical system on the basis of the motion vector and corrects image skip during inverse drive of focus.

Description

  The present invention relates to a camera system, and more particularly to measures against image skipping during moving image shooting.

  2. Description of the Related Art Conventionally, a phenomenon in which an image is moved due to a change in a lens position and the movement of the image is recorded by shooting due to focus drive during moving image shooting (hereinafter, this phenomenon is referred to as “image skip”) has occurred. It was. The image skip mechanism will be described below. In driving the focus lens, the focus lens holding barrel that holds the focus lens has a plurality of cam followers, and the cam followers are engaged with the cam members. When rotation is transmitted to the focus lens holding barrel, the cam follower moves along the cam formed on the cam member, and the focus lens is extended while rotating to perform focus drive. In such a configuration, if there is a backlash between the cam and the cam follower, the backlash is driven while the rotation direction is the same direction, but when the rotation direction is reversed, the backlash direction is changed, so that the backlash changes. It moves and starts driving. When moving this play, the above-mentioned image skip occurs.

  As a countermeasure against such image skipping, it is conceivable to perform backlashing of the cam and the cam follower so that there is no backlash. However, in the configuration in which the rattling removal urging is performed, there is a problem that the driving torque increases due to the urging. In particular, digital single-lens reflex cameras have recently been able to shoot movies. Lenses that can be attached to single-lens reflex cameras have a large lens group to be driven, which increases the biasing force and results in driving torque. Because it becomes heavy, it is not a realistic measure. On the other hand, Patent Document 1 proposes that a motion vector is detected from an image and an image stabilization lens is driven based on the result to correct image skipping.

Japanese Patent No. 3381095

  However, in the method described in Patent Document 1, it is impossible to detect an abrupt image movement that occurs at the time of inversion driving of the focus lens unless the motion vector detection sample time is high speed. Further, when the detection sample time is increased, the amount of light entering the image sensor for one frame is reduced, so that the information becomes unstable due to the influence of noise. Therefore, even if the motion vector detection sample time is increased, accurate image skip correction cannot be performed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a camera system that can accurately correct image skipping during focus inversion driving without increasing the motion vector detection sample time.

  In order to achieve the above object, a camera system according to an aspect of the present invention is a camera system capable of shooting a moving image, an imaging device that captures a subject image formed by an imaging optical system, and the imaging device A focus detection unit that detects a focus adjustment state of the imaging optical system based on a contrast detection method based on an output signal from the lens, and a focus drive control that controls driving of the focus lens based on a detection result of the focus detection unit Means, a motion vector detection means for detecting a motion vector from the output of the image sensor, and a correction drive control means for controlling the drive of the shake correction optical system based on the detection result of the motion vector detection means. The focus drive control means sets the focus lens that drives at the first drive speed in the first direction at the time of moving image shooting to the first direction. In the case of reverse driving in the opposite second direction, the focus lens is driven at a second drive speed that is slower than the first drive speed, and the correction drive control means is configured to cause the focus lens to move to the second drive speed. The shake correction optical system is driven based on a detection result of the motion vector detection means obtained while driving at a speed.

  According to the present invention, it is possible to provide a camera system capable of accurately correcting image skipping during focus inversion driving without increasing the motion vector detection sample time.

It is sectional drawing of the camera system which is embodiment of this invention. It is a block diagram of the camera system which is an embodiment of the present invention. It is a flowchart figure of the camera system which is embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a sectional view of a camera system representing an embodiment of the present invention. Reference numeral 1 denotes a camera body, and 2 denotes an attached interchangeable lens.

  3 is on the optical axis of the light beam that has passed through the interchangeable lens 2 before the start of photographing, and part of the light beam is guided to the viewfinder optical system and part of the light beam is split into the focus detection unit 5 through the sub-mirror 4 to photograph Inside is a mirror that retracts from the optical axis. The focus detection unit 5 includes a condenser lens that divides an incident light beam into two light beams, two separator lenses that re-image the light beam, and a phase difference method that includes a line sensor such as a CCD that photoelectrically converts the formed subject image. AF sensor. Reference numeral 6 denotes a semiconductor imaging unit (imaging device) such as a CMOS or a CCD that photoelectrically converts a light beam that has passed through the interchangeable lens 2 during imaging and photoelectrically converts the formed subject image. The data of the semiconductor imaging unit 6 is not only recorded but also used for contrast evaluation and motion vector detection during TV-AF during moving image shooting. The viewfinder optical system is composed of 7 pentaprisms and 8 viewfinder optical units.

  Reference numeral 11 denotes a first lens group, 12 denotes a second lens group (focus lens) serving as a focusing optical system, 13 denotes a third lens group serving as a variable power optical system, and 14 denotes a shake correction optical system. This is a fourth lens group (shake correction lens). Further, the amount of light that passes through the fourth lens group from the first lens group is limited by the diaphragm 15. The second lens group 12 serving as a focusing optical system receives a driving force from an AF driving motor 16 (focus driving unit), moves on the optical axis, and performs focus adjustment by stopping at a predetermined focusing position. The third lens group 13 serving as a variable magnification optical system is driven in the optical axis direction by a transmission mechanism (not shown) that transmits an operation from the photographer so as to be converted into a drive in the optical axis direction and zoomed. The fourth lens group 14 serving as a shake correction optical system moves in a direction perpendicular to the optical axis in response to the detection output from the angular shake detection sensor 17 such as a vibration gyro and the drive force from the shake correction drive unit 19. Perform angle shake correction.

  FIG. 2 is a block diagram of the camera system equipped with the photographing apparatus described in FIG. 1 according to the present invention. In the figure, 100 indicates a camera body, and 200 indicates an interchangeable lens body.

  A camera CPU 101 includes a microcomputer that controls the operation of various devices in the camera main body 100 as will be described later, and transmits and exchanges with the lens CPU 201 via the camera contact 102 when the interchangeable lens main body 200 is mounted. It is for receiving. The transmitted information includes focus lens drive information based on focus detection information, which will be described later, and exposure standby information as a signal received from the interchangeable lens body side. The camera contact 102 includes a signal transmission contact for transmitting a signal to the interchangeable lens body side and a power contact for supplying power to the interchangeable lens body side. Reference numeral 103 denotes a power switch means that can be operated from the outside, and is a switch for starting up the camera CPU 101 and enabling power supply to each actuator and sensor in the system and operation of the system. Reference numeral 104 denotes a selection switch (mode selection means) for selecting a moving image mode capable of moving image shooting or a still image mode capable of still image shooting, and the control of the camera system is changed depending on which mode is selected. . Reference numeral 105 denotes a two-stroke type release SW means which can be operated from the outside, and its signal is input to the camera CPU 101. In the still image mode, the camera CPU 101 performs a shooting preparation operation if the first stroke switch (SW1) is ON according to the signal input from the release SW means 105. Further, when it is detected that the second stroke switch (SW2) has been operated to ON, the mirror is raised and the exposure operation is started. Further, in the moving image mode, the camera CPU 101 performs mirror up and starts moving image shooting if the first stroke switch (SW1) is ON. A photometric unit 106 determines the exposure amount. Reference numeral 107 denotes still image distance measuring means, which measures the distance of the subject by the focus detection unit 5 in FIG. 1, detects the defocus amount, and transmits the defocus information to the camera CPU 101. An exposure means (shutter) 108 performs exposure by opening the shutter. An imaging unit 109 photoelectrically converts (captures) a subject image formed by an imaging optical system (first lens group to fourth lens group) in the interchangeable lens body, and is digitally converted by the signal processing unit 110. Output the image signal. The image data is recorded and stored in a recording medium such as a semiconductor memory such as a flash memory, a magnetic disk, and an optical disk by the image recording unit 111. Reference numeral 112 denotes a moving image distance measuring unit, which is a focus detecting unit that detects a focus adjustment state of the imaging optical system by a contrast detection method. The contrast value of the subject image is calculated from the output of the imaging unit 109 described above, and the calculated contrast information is transmitted to the camera CPU 101. Reference numeral 113 denotes a motion vector detection means, which calculates the moving direction and moving amount of the subject image from the output of the imaging unit 109 described above, and transmits the information to the camera CPU 101.

  Reference numeral 202 denotes a lens contact, which includes a signal transmission contact for transmitting a signal from the camera body side and a power contact for supplying power from the camera body side. Reference numeral 203 denotes an anti-shake operation SW means that can be operated from the outside, and can select whether or not to perform an image shake correction operation (anti-shake operation) (ON to select an anti-shake operation). Also transmitted to the main body 100. Reference numeral 204 denotes an angular shake detection means including a vibration gyro. In accordance with a command from the lens CPU 201, an angular velocity detection unit that detects the angular velocity of the vertical shake (pitch direction) and lateral shake (yaw direction) of the camera, and a displacement obtained by electrically or mechanically integrating the output signal of the detection unit. And an arithmetic output unit that outputs to the output. Reference numeral 205 denotes a correction drive control unit that corrects the angular shake and at the same time corrects the image skip during moving image shooting. The correction optical unit 206 includes the shake correction optical system 14 described in FIG. Further, the shake correction optical system 14 is driven in the X direction by a permanent magnet and a coil X direction drive means, and the shake correction optical system 14 is driven in the Y direction by a permanent magnet and a coil Y direction drive means. It has a shake correction drive unit that moves the optical system 14 to perform correction. A focus drive control unit 207 controls the focus drive unit based on AF information from the camera body. Reference numeral 208 denotes a focusing unit, which is composed of the focus driving unit controlled by the focus driving control unit 207 in the lens CPU 201 and the second lens group 12 driven by the focus driving unit as described above. Reference numeral 209 denotes a diaphragm unit, which includes a diaphragm driving unit (not shown) that is controlled by the lens CPU 201 in accordance with the diaphragm operation command transmitted from the camera CPU 101 as described above, and a diaphragm 15 that is driven by the diaphragm driving unit and determines the aperture area. It is configured.

  FIG. 3 is a flowchart showing main operations in the camera system shown in FIG.

  First, in step 1001 (hereinafter, step is indicated by S), the power switch means 103 of the camera body 100 is turned on, and the supply of power to the interchangeable lens body 200 is started. Here, S1001 is a step in which communication is started between the camera body 100 and the interchangeable lens body 200, for example, when a new battery is inserted or when the interchangeable lens body 200 is attached to the camera body 100. Also good. Next, in S1002, the camera CPU 101 detects the on / off state of SW1 of the release SW means 105. If it is on, the process proceeds to S1003, and if it is off, the process proceeds to S1002. In step S <b> 1003, the camera CPU 101 determines whether the moving image mode is set. In S1003, if the determined result is the moving image mode, the process proceeds to S1004, and if not, the process proceeds to S1013.

  Next, when the result determined in S1003 is the moving image mode (Y in S1003), photometry, AF (ranging operation), and recording are started by the camera CPU 101 in S1004, and AF (focusing) is started by the lens CPU 201. Operation) is started. In this AF, contrast is detected from the output of the image sensor, and contrast AF is performed to drive the focus lens to the contrast peak position. In step S1005, the lens CPU 201 drives the focus lens until a contrast peak is detected based on the detection result of the contrast AF. The normal driving speed (first driving speed) is selected as the driving speed at that time. In step S1006, when the camera CPU 101 detects that the contrast peak has been exceeded and an inversion command is issued, the lens CPU 201 selects the inversion driving speed (second driving speed) in step S1007 and reaches the peak position. The drive control is reversed and returned. In addition, the camera CPU 101 performs motion vector detection from the output of the image sensor at the same time as the inversion driving (S1008), and the lens CPU 201 drives the shake correction lens in a direction to alleviate image skipping based on the detection result to perform image skip correction. Done. In S1006, if the camera CPU 101 has not issued a reverse command, the process proceeds to S1011. In step S <b> 1009, the lens CPU 201 determines whether the predetermined amount of driving is performed in the reversal direction and the rattling removal driving is finished. The determination as to whether or not the rattling removal has ended is made based on whether or not the focus lens has been driven a predetermined amount in the reverse direction. More specifically, it is determined that the backlash removal has been stably completed by driving the focus lens by a slightly larger amount than the backlash generated by the cam and the cam follower. If it is determined that the rattling removal has ended, the lens CPU 201 selects the normal driving speed (first driving speed) as the driving speed (S1010), drives the focus lens at the normal driving speed, and proceeds to S1011. If it is determined that the rattling removal driving has not been completed, steps S1006 to S1009 are repeated. If it is determined in S1010 that the lens CPU 201 has finished the rattling removal driving, the image jumping and the switching from the reverse driving speed (second driving speed) to the normal driving speed (first driving speed) are performed. The driving of the shake correction lens for correction is also terminated. In S1011, the camera CPU 101 determines whether or not it is in focus. If it is determined that the camera is in focus, the lens CPU 201 once stops focus drive and proceeds to S1002 (S1012). If not in focus, the process proceeds to S1002.

  On the other hand, when the result determined in S1003 is not the moving image mode (N in S1003), the camera CPU 101 starts AE, AF, and focus detection (S1013), and the lens CPU 201 focuses based on the AF detection result. Driving is started (S1014). In step S1015, the camera CPU 101 determines whether or not the lens is in focus. If the lens is in focus, the lens CPU 201 stops focus driving (S1016), and proceeds to step S1017. If not in focus, the process proceeds to step S1002. In step S1017, the camera CPU 101 detects the on / off state of SW2 of the release SW unit 105. If it is on, the process proceeds to step S1018. If it is off, the process proceeds to step S1002. In step S1018, the camera CPU 101 starts an exposure operation, opens the shutter after the mirror is raised, exposes the image sensor, and records the output of the image sensor.

  With reference to the block diagram of FIG. 2 and the flowchart of FIG. 3, the focus drive operation when the moving image mode is selected and the image skip correction during the focus inversion drive, which are the subject of the present invention, will be described below.

  When the moving image mode is selected, the mirror is raised after the switch SW1 is turned on, and the exposure unit 108 opens the shutter to start moving image shooting. AF detection during moving image shooting is performed by the moving image distance measuring means 112 described above. Specifically, the contrast of the subject image based on the output of the imaging unit 109 is detected, the focus lens is driven in the same direction (first direction) at the normal driving speed (first driving speed), and the contrast peak is obtained. Drive until it exceeds. When it is determined that the contrast peak has been exceeded, the focus drive control means 207 drives the focus lens in a reverse direction in the second direction opposite to the first direction. At this time, the inversion driving speed is driven at a low speed driving speed (second driving speed slower than the first driving speed) so that the image skip can be detected by a motion vector. Simultaneously with the inversion driving, the motion vector detecting unit 113 detects the moving direction and moving amount of the subject image, and transmits the information to the correction driving control means 205. The correction drive control means 205 drives and controls the shake correction drive unit based on the moving direction and moving amount of the subject image, and corrects the image skip at the time of focus reversal. Since the image skip at the time of the inversion drive is caused by the play of the focus drive transmission unit, in addition to this play, a low speed drive is performed while the focus lens is driven by a predetermined amount. Then, by determining that the focus lens has been driven by a predetermined amount, it is determined that the rattling removal driving has been completed. When it is determined that the rattling removal driving is completed after the predetermined amount of inversion driving, the driving speed is returned from the low driving speed (second driving speed) to the normal driving speed (first driving speed), and the focus lens is moved to the contrast peak position. Perform return drive. In addition, the correction of the image skip by the correction drive control unit 205 is also completed with the switching from the low speed drive speed (second drive speed) to the normal drive speed (first drive speed). In other words, the correction drive control unit 205 performs the above-described image skip correction while the focus lens is being driven at the low speed drive speed (second drive speed) (while the backlash removal drive is being performed). With the above operation, the present invention can accurately correct the image skip accompanying the variation of the lens position.

  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.

  The present invention can be suitably used for an optical apparatus such as a video camera, a compact camera, or a single-lens reflex camera.

DESCRIPTION OF SYMBOLS 1 Camera body 2 Interchangeable lens 3 Mirror 4 Sub mirror 5 Focus detection part 6 Semiconductor imaging part 12 2nd lens group (focus lens)
14 Fourth lens group (shake correction optical system)
15 Aperture 16 Focusing Actuator 17 Angular Shake Detection Sensor 19 Shake Correction Drive Motor

Claims (3)

A camera system capable of video recording,
An image sensor for imaging a subject image formed by an imaging optical system;
Focus detection means for detecting a focus adjustment state of the imaging optical system based on a contrast detection method based on an output signal from the image sensor;
Focus drive control means for controlling the drive of the focus lens based on the detection result of the focus detection means;
Motion vector detection means for detecting a motion vector from the output of the image sensor;
Correction drive control means for controlling the drive of the shake correction optical system based on the detection result of the motion vector detection means,
The focus drive control means is configured to focus the focus lens that is driven at a first drive speed in a first direction in reverse motion in a second direction opposite to the first direction during moving image shooting. Driving the lens at a second drive speed that is slower than the first drive speed;
The correction drive control means drives the shake correction optical system based on a detection result of the motion vector detection means obtained while the focus lens is driven at the second drive speed. Camera system.   The focus drive control unit reversely drives the focus lens in the second direction when the focus detection unit determines that the contrast of the subject image based on the output of the image sensor exceeds a peak. The camera system according to claim 1.   The focus drive control means drives the focus lens in the second direction at the first drive speed after driving the focus lens in the second direction by a predetermined amount at the second drive speed. The camera system according to claim 1 or 2, characterized in that: