JP2010145494A - Camera system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately perform detection and correction of a focus shake regardless of the subject luminance. <P>SOLUTION: The camera system includes: a shake correction part 16 for correcting a shake in an optical axial direction (focus shake) by conforming the position of a focus lens 12 to the shake; a focal point detecting imaging element 5; and an acceleration detector 18. The camera system further includes a focus shake correction amount arithmetic part 210 which computes an instruction to be given to the correction part 16 based on information detected by the imaging element 5 or the detector 18. When the accumulation time of the imaging element 5 is a predetermined value or less, the focus shake correction is performed by use of the information detected by the imaging element 5. When the accumulation time exceeds the predetermined value, the focus shake correction is performed by use of the information detected by the detector 18. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical apparatus such as a camera system having a function of improving image blur correction accuracy.

  In many cases, optical devices such as cameras and interchangeable lenses are equipped with an image stabilization system that suppresses image blur due to camera shake.

  The camera shake is a vibration having a frequency of usually 1 Hz to 10 Hz. An anti-vibration system that can take a photograph with no image shake even when camera shake occurs at the time of exposure has a function of detecting and correcting vibration applied to the system. Specifically, the vibration of the optical device is detected, and the correction lens is displaced (optical image stabilization) according to the detection result, or the area to be cut out (output) is changed from the captured image. Note that vibration such as camera shake is obtained by arithmetic processing based on acceleration, angular acceleration, acceleration, angular displacement, and the like detected by a detection device such as a laser gyro or an acceleration sensor.

  By the way, in general, when the shooting magnification is 0.1 times or less, the image shake correction is sufficient only by correcting the angular shake in the direction in which the imaging surface is tilted. However, when the shooting magnification is larger than that, The effect of runout in the parallel direction becomes greater. Further, as the photographing magnification increases, the influence of shake in the focus direction (photographing optical axis direction) also increases. This is because the parallel shake occurs as a shift on the image plane in proportion to the shooting magnification, and the shake in the focus direction (focus shake) occurs as the focus shift in proportion to the square of the shooting magnification.

  For this reason, in an optical apparatus having a high photographing magnification such as a conventional macro lens, a proposal has been made to correct a parallel shake and a focus shake by controlling an optical shake correction unit by using a displacement sensor such as an acceleration sensor. For example, Patent Document 1 discloses a technical proposal that a camera shake is detected by a displacement sensor such as an acceleration sensor, a speed sensor, or a position sensor, and an automatic focusing operation (AF) is performed again during exposure to correct the focus shake. Has been made.

  In addition, a method for directly calculating a shake displacement from a displacement of an image formed, for example, a method for calculating a camera shake by detecting a shake of an image formed on an AF sensor has been proposed. In such a method, it is important to improve the responsiveness of the AF sensor. As an effective technique for this, Patent Document 2 discloses a technique of changing the detection cycle of the AF sensor in accordance with the subject brightness. Japanese Patent Application Laid-Open No. 2003-228688 discloses a technique for increasing the AF prediction accuracy by extending the detection cycle of the AF sensor when the subject brightness is low and further performing a prediction calculation.

In addition, as a method for calculating camera shake from acceleration detected by an acceleration sensor, Patent Document 4 discloses the following method. First, the gravitational acceleration component is removed from the signal indicated by the acceleration sensor using the correction value calculated based on the AF sensor signal. Further, the initial speed used when calculating the shake speed and the displacement is obtained from the signal of the AF sensor. As described above, the shake information of the optical device including the angular shake, the parallel shake, and the focus shake can be detected accurately and quickly by obtaining the shake information using both the focus detection imaging device such as the AF sensor and the acceleration sensor signal. can do.
Japanese Patent Laid-Open No. 10-312006 Japanese Patent Laid-Open No. 02-000813 JP 09-230442 A JP 2006-003439 A

  It is possible to correct the focus shake during exposure by the focus shake detection and correction disclosed in Patent Document 1. However, since the focus shake correction (that is, automatic focus adjustment) before the start of exposure is performed based on information detected by the AF sensor, for example, when the subject brightness is low, the responsiveness of focus shake detection deteriorates. This is because the charge accumulation time of the AF sensor, that is, the detection cycle becomes long, so that a short-period fluctuation cannot be detected.

  By using the technique disclosed in Patent Document 2, when the subject brightness is high, it is possible to improve the followability to shake. However, it does not lead to an improvement in followability when the luminance is low. Further, even when the technique disclosed in Patent Document 3 is used, it is difficult to fundamentally improve the followability with respect to shake.

  Further, Patent Document 4 discloses a method of performing shake correction using an AF sensor and an acceleration sensor regardless of whether exposure is in progress. However, in the embodiment, focus shake correction (that is, automatic focus adjustment) before the start of exposure is performed based on information detected by the AF sensor, and the method of focus shake correction using the AF sensor and the acceleration sensor is not clearly described. . Furthermore, when the subject brightness is high, it is possible to detect shake only with the photoelectric conversion element, and it is not efficient to use both.

  In actual photographing, it is important to be able to detect and correct focus shake with high accuracy not only during exposure but also before the start of exposure. This is because if there is a large difference between the focus position detected immediately before the start of exposure and the position of the focus lens at that time, the focus lens cannot be moved to the focus position by the start of exposure. . In addition, it is preferable that the shake can be accurately corrected even before the start of exposure from the viewpoint of the viewfinder appearance.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical apparatus that can be applied to a single-lens reflex camera and that can efficiently perform high-precision image blur correction regardless of subject brightness.

  In order to achieve the above object, as one aspect, the camera system of the present invention has the following configuration. The camera system causes a focus lens position to follow a shake (focus shake) in the optical axis direction and corrects the focus shake, and a focus detection imaging device that detects the shake in the optical axis direction. And an acceleration detection device. Furthermore, a focus shake correction amount calculation unit that calculates a command to be given to the shake correction unit based on information detected by the focus detection image sensor or the acceleration detection device, and a photographing magnification detection unit. In such a camera system having a focus shake correction function, when the accumulation time of the focus detection image sensor is equal to or less than a predetermined value, focus shake correction is performed using information detected by the focus detection image sensor. Do. In the camera system, when the accumulation time exceeds the predetermined value, focus shake correction is performed using information detected by the acceleration detection device.

  Further, the present invention as another aspect is characterized in that the selection of the focus shake correction is made effective when the photographing magnification detected by the photographing magnification detection unit in the camera system exceeds a predetermined value. The camera system according to claim 1.

  Furthermore, the present invention as another aspect is to enable selection of the focus shake correction when the defocus amount detected by the focus detection image sensor in the camera system is smaller than a predetermined value. The camera system according to claim 1, wherein

  According to the present invention, for example, when the subject brightness is high, that is, when the accumulation time of the AF sensor is smaller than a predetermined value, focus blur correction is performed using only the AF sensor. In addition, when the subject brightness is low, that is, when the accumulation time of the AF sensor exceeds a predetermined value, correction is performed using an acceleration sensor, so even when the subject brightness is low, camera shake detection and correction can be performed with high accuracy. Can be done.

  In addition, when the subject brightness is high, focus shake correction by the acceleration sensor is not performed, which is more efficient than when both are used to perform focus shake correction.

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

  FIG. 1 is a cross-sectional view of a lens interchangeable digital single-lens reflex camera representing an embodiment of the present invention. Here, the direction of the lens optical axis (photographing optical axis) AXL is defined as the Z direction, the direction orthogonal to the lens optical axis AXL and the horizontal direction of the two directions parallel to the imaging surface is the X direction and the vertical direction. Let the direction be the Y direction.

  Reference numeral 1 denotes a camera body (hereinafter simply referred to as a camera), and 2 denotes an interchangeable lens attached to the camera 1. In the camera 1, reference numeral 3 denotes a main mirror, which is arranged on the optical path of the light beam from the interchangeable lens 2 before the start of photographing, reflects a part of the light beam and leads it to the finder optical system (7, 8), The remaining light flux is transmitted. In this state, the sub mirror 4 is disposed behind the main mirror 3, and the light beam transmitted through the main mirror 3 is reflected and guided to the focus detection unit 5. The main mirror 3 and the sub mirror 4 are retracted from the optical path during photographing.

  The focus detection unit 5 has an AF sensor and performs focus detection (detection of the focus state of the interchangeable lens 2) by a so-called phase difference detection method. The AF sensor includes a condenser lens that splits an incident light beam into two, two separator lenses that re-image each split light beam, and a line sensor such as a CCD sensor that photoelectrically converts two imaged subject images. Composed. The line sensor is arranged in a cross shape so as to detect the image position of the subject in the vertical direction (Y direction) and the horizontal direction (X direction).

  Reference numeral 6 denotes an image sensor composed of a CCD sensor or a CMOS sensor, and a light beam from the interchangeable lens 2 forms an image on a light receiving surface (image surface) of the image sensor 6. The imaging element 6 photoelectrically converts the formed subject image and outputs an imaging signal. The exposure amount of the image sensor 6 is controlled by an electronically controlled focal plane shutter (not shown).

  The finder optical system includes a pentaprism 7 and an eyepiece lens 8.

  In the interchangeable lens 2, in order from the subject side, 11 is a first lens unit, 12 is a second lens unit as a focus lens, 13 is a third lens unit as a variable power lens, and 14 is a fourth lens as a shake correction lens. Is a unit. In addition, a diaphragm unit 15 is disposed between the third and fourth lens units 13 and 14, and adjusts the amount of light passing through the interchangeable lens 2 and reaching the camera 1 side. The lens units 11 to 14 and the aperture unit 15 constitute a photographing optical system.

  The second lens unit (focus lens) 12 receives the driving force from the AF motor 16 and moves on the optical axis AXL to adjust the focus.

  The third lens unit (magnification lens) 13 moves on the lens optical axis AXL by the operation force of the photographer being transmitted by a transmission mechanism (not shown), and performs magnification.

  The fourth lens unit (shake correction lens) 14 receives a driving force from the IS actuator 19 and moves in a direction orthogonal to the lens optical axis AXL to perform image shake correction.

  Specifically, first, shake information indicating the shake of the camera system is generated based on a signal from the angular velocity sensor 17 such as a vibration gyro provided on the interchangeable lens 2 side and a signal from the acceleration sensor 18. Further, the fourth lens unit has a drive amount (calculated from the shake displacement amount and the sensitivity of the shake correction lens) corresponding to the shake displacement amount indicated by the shake information in a direction opposite to the shake direction indicated by the shake information. The IS actuator 19 is controlled to drive 14.

  The acceleration sensor 18 can detect accelerations in three directions of X, Y, and Z. Further, the angular velocity sensor 17 and the acceleration sensor 18 are arranged on a plane that is orthogonal to the optical axis AXL of the photographing optical system and includes the principal point P of the photographing optical system. Thereby, both the angular velocity sensor 17 and the acceleration sensor 18 can detect the angular velocity and acceleration of the shake at the position corresponding to the principal point P.

  The drive control of the IS actuator 19 is performed by a lens CPU which will be described later. Further, the fourth lens unit 14 may rotate about a point on the optical axis and move substantially in the direction perpendicular to the optical axis, or may be a so-called variable apex angle prism. .

  FIG. 2 is a block diagram showing an electric circuit configuration of the interchangeable lens digital single-lens reflex camera system shown in FIG.

  In this figure, 100 is an electric circuit on the camera 1 side (hereinafter referred to as camera-side electric circuit), and 200 is an electric circuit on the interchangeable lens 2 side (hereinafter referred to as lens-side electric circuit).

  In the camera-side electric circuit, reference numeral 101 denotes a camera CPU composed of a microcomputer. The camera CPU 101 controls the operation of each component on the camera 1 side, and is provided on the interchangeable lens 2 via the camera contact 102 and the lens contact 202 on the interchangeable lens 2 side (hereinafter simply referred to as the lens 2 side). Communication with the CPU 201 is performed. Information communicated to the lens 2 side includes parallel shake information, focus shake information, and the like, which will be described later, and image magnification information and the like as signals received from the lens 2 side.

  The camera contact 102 includes a signal transmission contact for transmitting a signal to the lens 2 side and a power contact for supplying power to the interchangeable lens 2.

  A power switch 103 that can be operated from the outside is a switch that activates the camera CPU 101 to enable power supply to each actuator, sensor, and the like in the system and operation of the system.

  Reference numeral 104 denotes a two-stroke release switch that can be operated from the outside, and has a first stroke switch (SW1) and a second stroke switch (SW2). A signal from the release switch 104 is input to the camera CPU 101. The camera CPU 101 enters a shooting preparation state in response to the input of an ON signal from the first stroke switch (SW1), measures the subject brightness by the photometry unit 105, detects the AF sensor accumulation time, and determines the position by the focus detection unit 106. The focus detection by the phase difference detection method is started. The camera CPU 101 calculates the aperture value of the aperture unit 15, the exposure amount of the image sensor 6 (in the shutter speed), and the like based on the photometric result. Further, the camera CPU 101 determines the focus of the second lens unit 12 necessary for focusing on the subject to be photographed based on the focus detection information (defocus amount and defocus direction) that is the detection result of the focus state. The driving amount and driving direction are determined. Information on the driving amount and the driving direction is transmitted to the lens CPU 201. The lens CPU 201 controls the operation of each component in the lens 2.

  Further, upon receiving an ON signal from an IS (anti-vibration) switch 203 provided on the lens 2 side, the camera CPU 101 starts drive control of the fourth lens unit 14, that is, shake correction control. Here, based on the signal from the AF sensor, the parallel shake detection unit 108 provided on the camera 1 side, that is, utilizing the fact that the light beam from the subject to be focused on is displaced on the AF sensor. The image shake in the X and Y directions of the subject image formed on is detected. The detected shake of the subject image in the X and Y directions, that is, the parallel shake is transmitted to the lens CPU 201 as parallel shake information in the X and Y directions. Further, the focus shake detection unit 107 detects a shake in the focus direction (Z direction), that is, a focus shake displacement amount (including the direction) based on fluctuations in focus detection information, and transmits this to the lens CPU 201 as focus shake information. To do.

  When an ON signal is input from the second stroke switch (SW2), the camera CPU 101 transmits an aperture drive command to the lens CPU 201, and causes the aperture unit 15 to set the previously calculated aperture value. In addition, the camera CPU 101 transmits an exposure start command to the exposure unit 109 to perform a retracting (up) operation of the mirrors 3 and 4 and an opening operation of the shutter, and the imaging unit 110 including the imaging device 6 captures the subject image. Photoelectric conversion, that is, photographing is performed.

  An image pickup signal from the image pickup unit 110 (image pickup element 6) is converted into a digital signal by the signal processing unit 111, further subjected to various correction processes, and output as an image signal. The image signal (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 in the image recording unit 112.

  The lens contact 202 includes a signal transmission contact for exchanging signals with the camera 1 side, and a power contact for receiving power supply from the camera 1 side.

  An IS (anti-shake) switch 203 is operated by a photographer to select whether or not to perform image blur correction control. The ON signal from the IS switch 203 is also transmitted to the camera 1 side via the lens CPU 201.

  Reference numeral 204 denotes an angular velocity sensor denoted by reference numeral 17 in FIG. The angular velocity sensor 204 includes a detection unit that outputs an angular velocity signal indicating each angular velocity of vertical (pitch direction) shake and lateral (yaw direction) shake, which are angular shakes of the camera system, and an arithmetic output unit. The arithmetic output unit outputs to the lens CPU 201 a signal indicating displacement of the pitch direction shake and yaw direction shake (amount of angular shake displacement) obtained by electrically or mechanically integrating the angular velocity signal from the detection unit. is doing. The angular velocity sensor 204 is controlled to be turned on / off by a command signal from the lens CPU 201.

  Reference numeral 205 denotes an acceleration sensor denoted by reference numeral 18 in FIG. 1, which detects acceleration in three directions of X, Y, and Z orthogonal to each other mechanically, specifically, using an inertial force generated by vibration, A signal indicating acceleration is output to the lens CPU 201.

  Reference numeral 206 denotes an acceleration / velocity calculation unit which converts X, Y direction parallel shake information and Z direction focus shake information input from the camera 1 side according to shooting magnification information (which will be described later). , Converted into parallel and out-of-focus displacement amounts in the Z direction. Further, the parallel, focus shake speed and parallel and focus shake acceleration in the X, Y, and Z directions are calculated from the values.

  Here, if the angular shake is already corrected, the shake in the X and Y directions is regarded as only the parallel shake excluding the angular shake.

  Reference numeral 207 denotes a correction value calculation unit. The correction value calculation unit 207 first compares the parallel and focus shake acceleration calculated by the acceleration / speed calculation unit 206 with the acceleration (hereinafter referred to as sensor detection acceleration) indicated by the signal from the acceleration sensor 205. Further, the difference is calculated as a correction value for the acceleration obtained from the acceleration sensor 205. This correction value is calculated for each of the X, Y, and Z directions and stored as an acceleration correction value for each direction. This correction value corresponds to the gravitational acceleration. The correction value calculation in the correction value calculation unit 207 is repeated until the start of the exposure operation on the camera 1 side, and the acceleration correction value is updated and stored as needed.

  Reference numeral 208 denotes a shake displacement calculation unit, which adds a correction based on the acceleration correction value calculated by the correction value calculation unit 207 to the sensor detection acceleration obtained from the acceleration sensor 205, thereby obtaining a gravitational acceleration component from the sensor detection acceleration. Exclude. The corrected acceleration is integrated to obtain the shake speed, and this is further integrated. Thereby, based on the detection result of the acceleration sensor 205, the parallel and focus shake displacement amount excluding the gravitational acceleration component is calculated.

  Note that in the calculation of the shake speed and shake displacement, it is necessary to obtain the initial shake speed of the camera system, so the shake speed (parallel, focus shake speed) obtained by the acceleration / speed calculator 206 is set as the initial speed. To do.

  Reference numeral 209 denotes a shake synthesizing unit, which calculates the fourth from the parallel shake displacement amount by the acceleration sensor output calculated by the shake displacement calculation unit 208 and the angular shake displacement amount (pitch, yaw direction) obtained from the angular velocity sensor 204 output. The driving amount (shake correction amount) of the lens unit 14 is determined. Specifically, the shake displacement amount due to the parallel shake in the X direction and the shake displacement amount on the image plane due to the angular shake in the yaw direction are synthesized, and the shake displacement amount due to the parallel shake in the Y direction and the angle in the pitch direction are combined. The amount of shake displacement on the image plane due to shake is synthesized. Then, the drive amount and direction of the fourth lens unit 14 are determined from the combined shake displacement amount.

  Reference numeral 210 denotes a focus shake correction amount calculation unit that calculates a drive amount and direction for focus shake correction of the second lens unit 12 based on the above-described focus shake displacement amount.

  A correction drive control unit 211 selectively executes shake correction control based on angular shake or shake correction control based on a total value (combined value) of angular shake and parallel shake in response to the ON of the IS switch 203. . Specifically, when the magnification indicated by the imaging magnification information is lower than a predetermined value (for example, 0.2 to 0.3 times, more preferably 0.1 times), the correction drive control unit 211 The shake correction control based on only the angular shake is performed. In addition, when the magnification is in a macro range higher than the predetermined value, shake correction control based only on angular shake before the start of exposure, and after the start of exposure, the total displacement amount of angular shake and parallel shake is set. Based on the shake correction control.

  The acceleration / speed calculation unit 206 to the correction drive control unit 211 are provided in the lens CPU 201.

  A correction drive unit 212 includes the IS actuator 19 and its drive circuit shown in FIG. The IS actuator 19 is composed of an X-direction actuator composed of a permanent magnet and a coil that drives the fourth lens unit 14 in the X direction, and a Y-direction actuator composed of a permanent magnet and a coil that drives the fourth lens unit 14 in the Y direction. Is done. In the lens 2, a lock mechanism is provided for holding the fourth lens unit 14 at a position where the optical axis thereof substantially coincides with the lens optical axis AXL. In response to a command signal from the lens CPU 201, the correction drive unit 212 locks the lock mechanism when the IS switch 203 is turned off (when shake correction is stopped). Further, when the IS switch 203 is turned on (during shake correction operation), the lock mechanism is unlocked.

  Reference numeral 213 denotes an in-focus driving unit that drives the second lens unit 12 by driving the AF motor 16 according to the driving amount and driving direction information of the second lens unit 12 transmitted from the camera CPU 101.

  Reference numeral 113 denotes a focus shake correction selection unit. Before the start of exposure, the camera CPU 101 selects a command to be transmitted to the focusing drive unit 213 when the following conditions 1 to 4 are all satisfied or not. Specifically, when all of the conditions 1 to 4 are satisfied, the camera CPU 101 transmits the focus shake correction drive amount and the drive direction from the focus shake correction amount calculation unit 210 to the focus drive unit 213, and the AF motor 16 is turned on. Focus shake correction is performed by driving. In other cases, the camera CPU 101 transmits a driving amount and a driving direction based on the focus detection information (defocus amount and defocus direction) of the distance measuring means 106 to the in-focus driving unit 213 and performs automatic focus adjustment, that is, tracking AF. Performs shake correction in the focus direction.

  Condition 1: At shake correction control (IS switch is ON).

  Condition 2: The photographing magnification is higher than a predetermined value (for example, 0.2 to 0.3 times, more preferably 0.1 times).

  Condition 3: The defocus amount is smaller than a predetermined value (for example, Fδ, etc., F: aperture value, δ: allowable confusion circle diameter).

  Condition 4: AF sensor accumulation time is a predetermined value (for example, when the period of camera shake is 0.1 to 1 sec, 0.05 second that is ½ of the minimum period. Detected by the acceleration sensor 18 in addition. The run-out period may be used).

  Furthermore, when both the condition 1 and the condition 2 are satisfied, the focus shake correction selection unit 113 is in accordance with the focus shake correction drive amount and the direction information from the focus shake correction amount calculation unit 210 at the same time as the exposure operation starts. Make corrections.

  Reference numeral 214 denotes an aperture drive unit, which is controlled by the lens CPU 201 that has received an aperture drive command from the camera CPU 101, and operates the aperture unit 15 shown in FIG. 1 in an aperture state corresponding to the aperture value specified by the command.

  Reference numeral 215 denotes a photographing magnification detection unit, which includes a first detection unit that detects the position of the third lens unit 13 that is a variable power lens, a second detection unit that detects the position of the second lens unit 12, and the first and second detection units. It is comprised by the calculating part (all are not shown) which calculates imaging | photography magnification based on the positional information from a 2nd detection part. Information on the photographing magnification calculated by the calculation unit is transmitted to the acceleration / speed calculation unit 206 and also to the camera CPU 101 via the lens CPU 201.

  Next, the main operation of the system shown in FIG. 2 will be described by limiting the focus shake correction using the flowchart of FIG. First, when the power switch 103 in the camera-side electric circuit 100 is turned on, power supply to the lens-side electric circuit 200 is started, and communication between the camera CPU 101 and the lens CPU 201 is started (steps, <FIG. S >> 1001).

  Next, the camera CPU 101 determines whether or not the SW1 ON signal is generated in the release switch 104 (step 1002). When the ON signal is generated, the lens CPU 201 determines whether or not the IS switch 203 is ON (step 1003). When the IS switch 203 is ON, the process proceeds to step 1004. When the IS switch 203 is not ON, the process proceeds to step 1027.

  In step 1004, the camera CPU 101 detects the accumulation time A of the AF sensor by the photometry unit 105.

  In step 1005, the camera CPU 101 performs a focus detection operation by the focus detection unit 106, and the defocus amount Def and the defocus direction are obtained.

  In step 1006, the lens CPU 201 detects the positions of the second (focus) and third (magnification) lens units 12 and 13.

  Further, the lens CPU 201 uses the photographing magnification detection unit 215 to detect the in-focus position detected in step 1005 and the positions of the second and third lens units 12 and 13 detected in step 1006, that is, the focal length and subject distance information. Detect current shooting magnification. It is determined whether or not the current photographing magnification is larger than the predetermined value D, in other words, whether or not the macro region requires focus shake correction (step 1007). If it is determined that the area is the macro area, the process proceeds to step 1008. If the macro area is not determined, the process proceeds to step 1027.

  In step 1008, the lens CPU 101 determines whether or not the defocus amount Def detected in step 1005 is smaller than the predetermined value α. If it is determined that the value is smaller than the predetermined value, the process proceeds to step 1009. If it is not determined that the value is smaller, the process proceeds to step 1023. The reason why the defocus amount is determined here is that there is not much meaning even if fine shake correction is performed when the position of the second lens unit (focus lens) 12 is away from the in-focus position. It is. In such a case, first, the second lens unit (focus lens) 12 is driven to the in-focus position.

  Further, the lens CPU 201 determines whether or not the accumulation time A detected in Step 1004 exceeds a predetermined value E, in other words, whether or not the subject brightness is such that the AF sensor can accurately detect the focus shake (Step 1009). ). If the predetermined value E is exceeded, that is, if it is determined that the AF sensor cannot accurately detect the focus shake, the process proceeds to Step 1010. If it is determined that it can be detected with high accuracy, the process proceeds to step 1023.

  Further, the lens CPU 201 calculates a correction value by the correction amount calculation unit 207 from the acceleration in the focus shake direction (Z direction) detected by the acceleration detection unit 205 and the focus shake acceleration calculated by the acceleration / speed calculation unit 206. . Further, the focus shake correction amount calculation unit 210 calculates the focus shake correction drive amount, and obtains the position where the second lens unit (focus lens) 12 should be. (Step 1010).

  In step 1011, the lens CPU 201 detects the position of the second lens unit (focus lens) 12.

  Further, the lens CPU 201 determines whether or not the lens position calculated based on the acceleration sensor information obtained in step 1010 and the position of the second lens unit (focus lens) 12 detected in step 1011 are the same (step). 1012). If they are the same, the process proceeds to step 1014, and if they are different, the process proceeds to step 1013. In step 1013, the lens CPU 201 drives the second lens unit (focus lens) 12 by the amount corresponding to the difference in step 1012, and proceeds to step 1010 again.

  In step 1014, it is determined whether or not the ON signal from SW2 is input by the second stroke operation of the release button, and steps 1002 to 1014 are repeated until the ON signal is input. When the ON signal from SW2 is input, the process proceeds to step 1015.

  In step 1015, the camera CPU 101 starts the exposure operation of the image sensor 6, and at the same time, the lens CPU 201 corrects the focus shake. Steps 1016 to 1019 are the same processing as steps 1010 to 1013. Steps 1016 to 1019 are repeated until the exposure is completed.

  When the exposure operation ends in this way (step 1021), the process proceeds to step 1022, where the camera CPU 101 records the photographed image data on the recording medium, and returns to step 1002.

  If the accumulation time A of the AF sensor does not exceed the predetermined value E in step 1009, that is, if it is determined that the focus shake can be accurately detected using the AF sensor, the process proceeds to step 1023. Next, the camera CPU 101 detects the in-focus position as in step 1004 (step 1023), and detects the position of the second unit (focus lens) 12 (step 1024). In step 1025, the lens CPU 201 determines whether or not the in-focus position and the position of the second lens unit (focus lens) 12 are the same. If they are the same, the process proceeds to step 1014, and if they are different, the process proceeds to step 1026. In step 1026, the second lens unit (focus lens) 12 is driven by the amount of the difference in step 1025, and the process proceeds to step 1023 again.

  If it is determined in step 1008 that the defocus amount is greater than or equal to a predetermined value, the process proceeds to step 1023. After that, it is as described above.

  If it is determined in step 1007 that the imaging magnification is equal to or smaller than a predetermined value, that is, it is not a macro area, the process proceeds to step 1027. Steps 1027 to 1030 are the same processes as steps 1023 to 1026. Steps 1002 to 1031 are repeated until an ON signal is input from SW2. When the ON signal from SW2 is input, the process proceeds to the exposure operation in step 1032. In this case, focus shake correction is not performed during exposure.

  If the IS switch 203 is OFF in step 1003, the process proceeds to step 1027. From step 1027, it is as described above.

  The camera CPU 101 and the lens CPU 201 repeat the above series of operations until the power switch 103 is turned off. When the power switch 103 is turned off, the communication between the camera CPU 101 and the lens CPU 201 is terminated, and the power supply to the lens-side electric circuit 200 is also terminated.

  Next, the difference in the tracking error with respect to the focus shake (L1) when the present embodiment is applied when the subject brightness is high, when the subject brightness is low, and when the brightness is low will be described with reference to FIG. 4A shows a case where the present embodiment is applied when the subject brightness is low, FIG. 4B shows a case where the subject brightness is high, and FIG. 4C shows a case where the subject brightness is low. The accumulation time of the AF sensor when the subject brightness is low is represented by T1, and the accumulation time when the subject brightness is high is represented by T2.

  Based on the detection results of the past three points detected by the focus detection unit (P1 to P3 in FIGS. 4A and 4C, P5 to P7 in FIG. 4B) (see FIGS. 4A and 4C). L2 and (B) L3) are estimated, and future focus shake is predicted. A command is given to the focus driving unit 213 so that the second lens unit (focus lens) 12 moves to the predicted future position (P4 in FIG. 4A, P8 in (B), P9 in (C)). ing. However, in FIG. 4C, that is, in this embodiment, interpolation is performed using the acceleration sensor signal (S1) in addition to the past three points detected by the focus detection unit, for example.

  4A to 4C, when the subject brightness is low (A) and when the subject brightness is high (B), it can be seen that (B) can follow the shake more accurately. In addition, even when the luminance is low, it can be seen that if this embodiment is applied (C), tracking can be performed with the same degree of accuracy as when the subject luminance is high (B).

  In this embodiment, whether or not to perform focus shake correction using the acceleration sensor is determined based on the magnitude of the accumulation time of the AF sensor and a predetermined value, but the present invention is not limited to this. For example, the luminance of the subject may be detected instead of the accumulation time of the AF sensor to determine the magnitude of the predetermined value.

  In the present embodiment, the case where the parallel shake and the focus shake are detected using the output from the AF sensor has been described. However, the present invention is not limited to this, and for example, the output from the image sensor 6 may be used. May be detected.

  In this embodiment, the output from the AF sensor is used to calculate the correction value of the acceleration detected by the acceleration sensor 205 (exclusion of gravitational acceleration) and to calculate the initial speed necessary for calculating the speed based on the acceleration. The case where it is used for obtaining the above has been described. However, the present invention is not limited to this. For example, it may be used only for one calculation, or the gravitational acceleration may be excluded from the information detected by the acceleration sensor without using the AF sensor and the initial velocity may be obtained. Good.

  In this embodiment, the case where the correction of parallel shake is started simultaneously with the start of exposure has been described. However, the correction of parallel shake may be started before the start of exposure.

  Further, in the present embodiment, the parallel shake detection unit 108, the focus shake detection unit 107, and the focus shake correction selection unit 113 are provided on the camera 1 side, and the angular velocity sensor 204, the acceleration sensor 205, and the CPU that performs shake correction control are the lenses 2 The case where it is provided on the side has been described. However, the present invention is not limited to this, and each of these components may be provided on either the camera side or the lens side.

  For example, an angular velocity sensor and an acceleration sensor may be provided on the camera side together with the parallel shake detection unit and the focus shake detection unit, and an output signal from these may be taken in by the CPU on the lens side to perform shake correction control. Furthermore, the parallel shake detection unit and the focus shake detection unit provided on the lens side may take in signals from the AF sensor on the camera side, and calculate the parallel shake and the focus shake. Alternatively, the CPU on the camera side may perform all calculations necessary for shake correction, and transmit a drive command (drive amount and direction command) for the fourth lens unit 14 to the lens side.

  Further, although the present embodiment has been described with respect to a lens interchangeable digital single-lens reflex camera, the present invention can also be applied to a digital camera on a lens-integrated side, and further to a video camera.

  In this embodiment, the case of performing so-called optical image stabilization has been described. However, the present invention shifts the output area of the image signal acquired by the image sensor according to the shake, or enlarges / reduces the area. It can also be applied to so-called electronic image stabilization.

1 is a cross-sectional view showing a lens interchangeable digital single-lens reflex camera that is an embodiment of the present invention. The block diagram which shows the electric circuit structure of the said camera system. 7 is a flowchart showing main operations in the camera system. The figure which compared the tracking error in the case where a to-be-photographed object brightness | luminance is high and low, and a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera body 2 Interchangeable lens 3 Main mirror 4 Sub mirror 5 Focus detection unit 6 Image pick-up element 12 2nd lens unit (focus lens)
14 Fourth lens unit (shake correction lens)
15 Aperture unit 16 AF motor 17 Angular shake sensor 18 Acceleration sensor 19 IS actuator

Claims (3)

A shake correction unit that corrects the focus shake by causing the position of the focus lens to follow a shake (focus shake) in the optical axis direction, an image sensor for focus detection that detects a shake in the optical axis direction, and an acceleration detection device A focus shake correction unit, a focus shake correction amount calculation unit that calculates a command to be given to the shake correction unit based on information detected by the focus detection imaging device or the acceleration detection device, and a photographing magnification detection unit In a camera system having a function,
When the accumulation time of the focus detection image sensor is equal to or less than a predetermined value, performing focus shake correction using information detected by the focus detection image sensor,
A camera system, wherein when the accumulation time exceeds the predetermined value, focus shake correction is performed using information detected by the acceleration detection device.   The camera system according to claim 1, wherein the camera system enables the selection of the focus shake correction when the shooting magnification detected by the shooting magnification detection unit exceeds a predetermined value.   2. The camera according to claim 1, wherein the camera system enables selection of the focus shake correction when a defocus amount detected by the focus detection image sensor is smaller than a predetermined value. system.

Images