JP2009284117A - Imaging device and method of controlling imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device which prevents contrast AF from decreasing in precision due to a hand shake and is reduced in battery consumption, and to provide a method of controlling the imaging device. <P>SOLUTION: The imaging device includes an imaging element 221 which picks up a subject image through a taking lens 101 and outputs an image signal, a contrast AF circuit 253 which detects a contrast value in an AF detection area 33 of the image signal, a body CPU (AF control unit) 251 which adjusts the focus of the taking lens 101 so as to obtain a maximum contrast value, and a hand shake amount detecting circuit 22 which detects a hand shake amount, the AF detection area 33 being changed according to the hand shake amount (#117). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus and a method for controlling the imaging apparatus, and more particularly to an imaging apparatus having both a contrast AF function and a camera shake correction mechanism (anti-vibration mechanism) and a method for controlling the imaging apparatus.

  Most of the automatic focus adjustment mechanisms of digital cameras in recent years adopt a contrast method. This method repeatedly detects a contrast value (sharpness) in a partial region of the subject image signal while driving the focus adjustment lens, and stops the focus adjustment lens at a position where the contrast value is the highest ( Hereinafter, the automatic focus adjustment operation by this method is referred to as contrast AF). In contrast AF, since the in-focus state is determined by comparing the previous and current contrast values, if camera shake occurs during that time, the detection accuracy may be lowered, and focus adjustment may become impossible.

By the way, recent digital cameras are increasingly equipped with a camera shake correction mechanism (also referred to as an image blur correction mechanism or an image stabilization mechanism). This mechanism includes an optical system correction system that drives some lenses (camera shake correction lens) of the photographic optical system so as to cancel out vibrations applied to the camera, and directly drives the image sensor inside the camera body. And an imaging system correction method. Therefore, it is considered that the above-described problem in contrast AF can be solved by operating any one of the camera shake correction mechanisms when performing contrast AF. Japanese Patent Application Laid-Open No. 2005-228561 discloses a camera that performs camera shake correction using an optical system correction method during execution of contrast AF.
JP 2001-166201 A

  In general, when contrast AF is performed, the focus adjustment lens is driven while repeating the imaging operation, so that power consumption during that time is very large. In addition, operating the camera shake correction mechanism for the camera shake correction operation causes short-term battery consumption.

  The present invention has been made in view of such circumstances, and provides an imaging apparatus and an imaging apparatus control method that prevent the accuracy of contrast AF from being reduced due to camera shake and that consume less battery power. With the goal.

  In order to achieve the above object, an image pickup apparatus according to a first invention picks up a subject image via a taking lens and outputs an image signal, and a contrast for detecting a contrast value for a specific region of the image signal. A detection unit; an AF control unit that adjusts the focus of the photographing lens so that the contrast value is maximized; and a camera shake detection unit that detects a camera shake amount. The specific area is changed based on the amount.

  An image pickup apparatus according to a second invention includes a camera shake correction unit that performs a camera shake correction operation that cancels camera shake applied to the image pickup apparatus based on the camera shake amount in the first invention, and the AF control unit Thus, the camera shake correction operation by the camera shake correction unit is prohibited while the focus of the photographing lens is being adjusted.

  An imaging apparatus according to a third invention includes a determination unit that determines whether or not the specific region exceeds a changeable range in the first invention, and the specific region can be changed by the determination unit. When it is determined that the range has been exceeded, the contrast detection unit fixes the specific area.

  An imaging device according to a fourth invention is the imaging device according to the first invention, wherein the photographing lens is a variable focal length lens, and the imaging device further includes a focal length detection mechanism for detecting focal length information of the photographing lens. The contrast detection unit changes the specific area based on the focal length information in addition to the information on the amount of camera shake.

  According to a fifth aspect of the present invention, there is provided a method for controlling an imaging apparatus, comprising: detecting a contrast value for a specific region of an image signal output from an image sensor; and adjusting a focus of a photographing lens so that the contrast value is maximized. In the image pickup apparatus control method capable of executing the above, the amount of camera shake generated during the execution of the contrast AF operation is detected, and the specific area is changed according to the amount of camera shake.

  According to the present invention, the amount of camera shake occurring during the execution of the contrast AF operation is detected, and the specific area is changed according to the amount of camera shake. Therefore, the accuracy of contrast AF decreases due to camera shake. It is possible to provide an imaging device and a method for controlling the imaging device that can prevent the above-described problem and reduce battery consumption.

  Hereinafter, preferred embodiments using a digital camera to which the present invention is applied will be described with reference to the drawings. In the digital camera according to the embodiment of the present invention, an anti-vibration mechanism having a camera shake sensor is disposed. In response to the half-pressing operation of the release button, a shooting preparation state is set, and shooting is started in response to the full-pressing of the release button. The image data of the still image acquired at this time is recorded on the recording medium. In the shooting preparation state, contrast AF is executed, and the focus of the shooting lens is adjusted so that the contrast information of the image data of the specific area based on the output of the image sensor is maximized. At this time, the contrast AF detection area in the shooting screen is moved based on the output of the camera shake sensor. Note that the camera shake correction mechanism is not driven during contrast AF.

  FIG. 1 is a block diagram showing an overall configuration mainly including an electric system of a digital camera according to an embodiment of the present invention. The digital camera according to this embodiment includes an interchangeable lens 100 and a camera body 200 and is electrically connected through a communication contact 291. Note that the interchangeable lens 100 and the camera body 200 may be configured integrally.

  Inside the interchangeable lens 100, a photographing lens 101 for focus adjustment and focal length adjustment, and a diaphragm 103 for adjusting the aperture amount are arranged. The photographing lens 101 is driven by a lens driving mechanism 107, and the diaphragm 103 is connected to be driven by a diaphragm driving mechanism 109. The photographing lens 101 is constituted by a zoom optical system, and the zoom value detection mechanism 105 detects the focal length of the photographing lens 101.

  The zoom value detection mechanism 105, the lens driving mechanism 107, and the aperture driving mechanism 109 are each connected to a lens CPU 111, and the lens CPU 111 is connected to the camera body 200 via a communication contact 291. The lens CPU 111 controls the inside of the interchangeable lens 100. The lens CPU 111 controls the lens driving mechanism 107 to perform focusing and zoom driving, and also controls the aperture driving mechanism 109 to perform aperture value control. Further, the focal length of the taking lens 101 is detected from the zoom value detection mechanism 105, and this zoom information is transmitted to the camera body 200.

  In addition, in the lens CPU 111 or an electrically rewritable memory such as an EEPROM (not shown), focal length information of the interchangeable lens 100 (shortest focal length and longest focal length in the case of a zoom lens), open aperture value, minimum Lens information such as an aperture value, lens color balance information, aberration information, and information for AF is stored. Such lens information is transmitted from the lens CPU 111 to the camera body 200 via the communication contact 291.

A focal plane type shutter 213 for controlling the exposure time is disposed in the camera body 200 and behind the taking lens 101. The shutter 213 is driven and controlled by a shutter drive mechanism 237. An image sensor 221 is disposed behind the shutter 213 and photoelectrically converts a subject image formed by the photographing lens 101 into an electric signal. The imaging element 221 may be a CCD (Charge Coupled Devices) or a CMOS (Complementary).
Needless to say, a two-dimensional image sensor such as Metal Oxide Semiconductor can be used.

  The image sensor 221 is connected to the image sensor drive circuit 223, and the image sensor drive circuit 223 reads an image signal from the image sensor 221. The output of the image sensor 221 is connected to a pre-processing circuit 225. The pre-processing circuit 225 performs pre-processing for image processing such as pixel thinning processing for live view display and clipping processing for enlarged display. Do.

  A dustproof filter 215, a piezoelectric element 216, and an infrared cut filter / low pass filter 217 are disposed between the shutter 213 and the image sensor 221. A piezoelectric element 216 is fixed around the dust filter 215, and this piezoelectric element 216 is vibrated by ultrasonic waves by a dust filter driving circuit 235. The dust attached to the dustproof filter 215 is removed by the vibration wave generated in the piezoelectric element 216.

  The infrared cut filter / low pass filter 217 is an optical filter for removing the infrared light component and the high frequency component from the subject light flux. An image pickup unit 219 including a dustproof filter 215, a piezoelectric element 216, an infrared cut filter / low pass filter 217, and an image pickup element 221 is integrally formed in an airtight manner so that dust and the like do not enter. The image pickup unit 219 including these integrated image pickup elements 221 and the like can be moved by the image stabilization mechanism 233 along the X-axis direction and the Y-axis direction on the image pickup surface of the image pickup element 221.

  This anti-vibration mechanism 233 includes a vibration sensor that detects vibration due to camera shake applied to the camera body 200, and a camera shake correction controller that generates a camera shake correction signal for removing vibrations such as camera shake based on the output of the vibration sensor. And a camera shake correction signal from the camera shake correction controller, and based on this signal, a drive mechanism for shifting the image sensor 221 along the imaging surface, and a position of the image sensor 221 driven by the drive mechanism are detected. It consists of a position detection sensor or the like. The image stabilization mechanism 233 moves the image pickup device 221 and the like so as to cancel vibrations such as camera shake applied to the camera body 200 to perform image stabilization. The vibration isolation mechanism 233 will be described later with reference to FIG.

The pre-processing circuit 225 is an ASIC (Application Specific
(Integrated Circuit: Application Specific Integrated Circuit) 250 is connected to the data bus 252. The data bus 252 includes a sequence controller (hereinafter referred to as “body CPU”) 251, an image processing circuit 257, a compression / decompression circuit 259, a video signal output circuit 261, an SDRAM control circuit 265, an input / output circuit 271, and a communication circuit 273. A recording medium control circuit 275, a flash memory control circuit 279, and a switch detection circuit 283 are connected.

  The body CPU 251 connected to the data bus 252 controls the operation of this digital camera. A contrast AF circuit 253 is connected between the preprocessing circuit 225 and the body CPU 251 described above. The contrast AF circuit 253 extracts a high frequency component based on the image data output from the preprocessing circuit 225, and outputs contrast information based on the high frequency component to the body CPU 251. The extraction of the high frequency component is performed using the image signal in the AF detection area 33 (see FIG. 7) among the image signals output from the preprocessing circuit 225.

  The image processing circuit 257 connected to the data bus 252 is a variety of images such as digital amplification (digital gain adjustment processing) of digital image data, color correction, gamma (γ) correction, contrast correction, and live view display image generation. Perform processing. Further, the image processing circuit 257 obtains the luminance of the subject from the image data output from the image sensor 221.

  The compression / decompression circuit 259 is a circuit for compressing the image data stored in the SDRAM 267 by a compression method such as JPEG or TIFF, and decompressing the compressed and recorded image data. Note that image compression is not limited to JPEG or TIFF, and other compression methods can be applied.

  The video signal output circuit 261 is connected to the rear liquid crystal monitor 26 via the liquid crystal monitor drive circuit 263. The rear liquid crystal monitor 26 is disposed on the rear surface of the camera body 200. However, the rear liquid crystal monitor 26 is not limited to the rear surface and may be another display device as long as it can be observed by the photographer. The rear liquid crystal monitor 26 is a display device that performs live view display, reproduces and displays a captured subject image, and displays shooting information and menus.

  The video signal output circuit 261 displays image data stored in the SDRAM 267 and the recording medium 277, image data for live view output from the image processing circuit 257, and other various information for camera control on the rear liquid crystal monitor. 26 is a circuit for converting into a video signal to be displayed on H.26.

  The SDRAM 267 is connected to the data bus 252 via the SDRAM control circuit 265, and the SDRAM 267 temporarily stores the image data processed by the image processing circuit 257 or the image data compressed by the compression / decompression circuit 259. This is a buffer memory.

  The input / output circuit 271 connected to the above-described image sensor driving circuit 223, anti-vibration mechanism 233, dustproof filter driving circuit 235, and shutter driving mechanism 237 inputs / outputs data to / from each circuit such as the body CPU 251 via the data bus 252. To control.

  A communication circuit 273 connected to the lens CPU 111 via a communication contact 291 is connected to the data bus 252 and exchanges data and communicates control commands with the body CPU 251 and the like. A recording medium control circuit 275 connected to the data bus 252 is connected to the recording medium 277 and controls recording of image data and the like on the recording medium 277 and reading of the image data and the like.

  The recording medium 277 can be loaded with any rewritable recording medium such as an xD picture card (registered trademark), a compact flash (registered trademark), an SD memory card (registered trademark), or a memory stick (registered trademark). And is detachable from the camera body 200. In addition, the hard disk may be configured to be connectable via a communication contact.

  The flash memory control circuit 279 is connected to a flash memory 281, and the flash memory 281 stores a program for controlling the operation of the digital camera. The body CPU 251 stores the program in the flash memory 281. Control the digital camera according to the program. Note that the flash memory 281 is an electrically rewritable nonvolatile memory.

  Various switches 285 including a 1R switch for detecting the first stroke (half press) of the release button and a 2R switch for detecting the second stroke (full press) are connected to the data bus 252 via the switch detection circuit 283. Yes. The various switches 285 include a power switch linked to the power button, a menu switch linked to the menu button, a playback switch linked to the playback button, and other various switches linked to other operation members. When the power switch is turned on, the camera can be set to the operating state.

  The switch detection circuit 283 detects on / off states of the switches of the various switches 285. The switch detection circuit 283 is connected to an attachment / detachment detection switch 287. The attachment / detachment detection switch 287 is a switch for detecting whether the interchangeable lens 100 is attached to or removed from the camera body 200.

  Next, a configuration related to the image stabilization operation will be described with reference to FIG. FIG. 2 is a block diagram showing a configuration related to the image stabilization operation including the image stabilization mechanism 233, including a specific configuration not shown in FIG. The vibration isolation mechanism 233 includes a camera shake correction controller 20, an XY direction vibration sensor 21, a camera shake amount detection circuit 22, a drive mechanism 23, and a position detection sensor 24.

  The image pickup device 221 provided in the camera body 200 is supported by a movable support member 27 (which is a part of the image pickup unit 219). The movable support member 27 is driven by the drive mechanism 23 in the x-axis direction and the y-axis direction. Each is free to move.

  The XY direction vibration sensor 21 detects vibration caused by hand shake or the like applied to the camera body 200 and outputs a hand shake signal. As the XY direction vibration sensor 21, an acceleration sensor, an angular acceleration sensor, or the like is used. The camera shake amount detection circuit 22 receives a camera shake signal from the XY direction vibration sensor 21 and outputs camera shake amount information corresponding to the camera shake amount to the ASIC 250 and the camera shake correction controller 20 based on this signal.

  The camera shake correction controller 20 is a control unit of the image stabilization mechanism 233, receives a control signal from the body CPU 251 in the ASIC 250, inputs camera shake amount information from the camera shake amount detection circuit 22, and is a movable support member from the position detection sensor 24. The position signal indicating the position 27 (including the image sensor 221), the initial position signal, and the movable terminal signal are input. Here, the position signal is a signal indicating the current position of the movable support member (image sensor 221), the initial position signal is a signal indicating the initial position of the movable support member (usually the centering position), and the movable end signal is movable. It is a signal which shows the terminal position in the movement range of a supporting member.

  Control signals input from the body CPU 251 by the camera shake correction controller 20 include a camera shake correction operation start command, a camera shake correction operation stop command, and a camera shake correction mechanism centering command. When the camera shake correction controller 20 receives a control command from the body CPU 251, the camera shake correction controller 20 causes the drive mechanism 23 to execute an operation in accordance with the control signal.

  The drive mechanism 23 is a drive mechanism that drives the movable support member 27 that holds the image sensor 221 in the x-axis direction and the y-axis direction in accordance with a shake correction signal or a centering control signal from the shake correction controller 20. A shake correction operation (anti-vibration operation) and a centering operation are executed by these members. When the position detection sensor 24 reaches the end of the movable range of the movable support member 27 that holds the image sensor 221, as described above, the fact is transmitted to the camera shake correction controller 20.

  Next, the operation of the digital camera in one embodiment of the present invention will be described using the flowcharts shown in FIGS. FIG. 3 shows a power-on reset operation by the body CPU 251 on the camera body 200 side. When a battery is loaded in the camera body 200, this flow starts, and it is first determined whether the power switch of the camera body 200 is on (# 1).

  If the result of determination in step # 1 is that the power switch is off, it enters a sleep state that is a state of low power consumption (# 3). In this sleep state, interrupt processing is performed only when the power switch is turned on, and processing for turning on the power switch is performed in step # 5 and subsequent steps. Until the power switch is turned on again, operations other than the power switch interrupt processing are stopped to prevent the power battery from being consumed.

  If the result of determination in step # 1 is that the power switch is on, or if the sleep state is exited in step # 3, power supply is started (# 5). Next, a dust removing operation is performed in the dust filter 215 (# 7). In this operation, a driving voltage is applied from the dust filter driving circuit 235 to the piezoelectric element 216 fixed to the dust filter 215, and dust and the like are removed by ultrasonic vibration waves.

  Subsequently, the camera shake correction mechanism is centered (# 9). In this step, the centering operation of the movable support member 27 (the image sensor 221) is performed by outputting a centering control signal to the vibration isolation mechanism 233. When the initial position signal is received from the position sensor 24, the centering operation is stopped.

  When an instruction for the centering operation of the camera shake correction mechanism is given, the live view operation is then started (# 11). In this step, the live view starts displaying a subject image on the rear liquid crystal monitor 26 based on the image data acquired by the image sensor 221.

  When the live view operation is started, it is next determined whether or not the playback switch is on (# 17). The playback mode is a mode in which the still image data recorded on the recording medium 277 is read and displayed on the rear liquid crystal monitor 26 when the playback button is operated. If the result of determination is that the regeneration switch is on, regeneration operation is executed (# 33).

  If the result of determination in step # 17 is that the playback switch is not on, it is determined whether or not the menu switch is on (# 19). In this step, it is determined whether the menu button 37 is operated and the menu mode is set. If the result of determination is that the menu switch is on, a menu is displayed on the rear liquid crystal monitor 26 and menu setting operation is performed (# 35). Various setting operations such as AF mode, white balance, ISO sensitivity setting, and drive mode setting can be performed by the menu setting operation. Whether or not to perform live view display is also set by this menu setting operation.

  If the result of determination in step # 19 is that the menu switch is not on, it is determined whether or not the release button has been pressed halfway, that is, whether or not the 1R switch is on. If the result of determination is that the 1R switch is on, a shooting operation subroutine for shooting preparation and shooting is executed (# 37). Details of this subroutine will be described later with reference to FIG.

  If the result of determination in step # 21 is that the 1R switch is not on, it is determined whether or not the interchangeable lens 100 has been removed (# 22). In this step, the state of the attachment / detachment detection switch 287 is detected and determined. If the result of this determination is that the interchangeable lens 100 has been removed, the live view operation is stopped (# 38). Since the interchangeable lens 100 is removed and no subject image is formed on the image sensor 221, the live view display is stopped. Subsequently, power supply to the camera body 200 and the interchangeable lens 100 is stopped (# 39).

  When the power supply is stopped, it is next determined whether or not the interchangeable lens 100 is attached (# 41). If the result of determination is that it is not attached, a standby state is returned to step # 41. Even if the power supply is stopped in step # 39, the power supply is supplied to the control system such as the body CPU 251 and the attachment / detachment detection switch 287, and it can be determined whether or not the interchangeable lens 100 is attached. If the result of determination in step # 41 is that lens mounting has been detected, processing returns to step # 5.

  If the result of determination in step # 22 is that the interchangeable lens 100 has been attached, it is determined whether or not the power switch is on, as in step # 1 (# 23). If the result of determination is that the power switch is on, processing returns to step # 16 and the above operation is repeated. On the other hand, if the power switch is not on, the power supply is stopped (# 25), the process returns to step # 3, and the above-described sleep state is entered. When the power supply is stopped in step # 25, the live view operation is also stopped.

  Next, a sub-routine of the photographing operation in step # 37 will be described using FIG. In the shooting operation subroutine, first, contrast AF is executed (# 51). In this step, the photographing lens 101 is driven via the lens CPU 111 and the lens driving mechanism 107 so that the contrast information output from the contrast AF circuit 253 has a peak value. The contrast AF subroutine will be described later with reference to FIG.

  When contrast AF is executed, photometric / exposure amount calculation is then performed to determine exposure control values such as shutter speed and aperture value (# 53). In this step, the image processing circuit 257 obtains the subject brightness based on the image data acquired from the image sensor 221, and the body CPU 251 calculates the exposure amount based on the subject brightness, and the exposure mode is used for the shooting mode / shooting. The exposure control values such as the shutter speed and the aperture value are calculated according to the conditions. The calculated exposure control value is displayed on a display unit such as a rear liquid crystal monitor 26 or a control panel (not shown).

  Subsequently, it is determined whether or not the release button has been fully pressed, that is, whether or not the 2R switch is on (# 55). If the result of this determination is that the 2R switch is not on, it is determined whether or not the release button has been pressed halfway, that is, whether or not the 1R switch is on (# 81). As a result of this determination, if the 1R switch is not on, that is, if the hand is released from the release button, the flow returns to the original flow. On the other hand, if the result of determination in step # 81 is that the 1R switch is on, processing returns to step # 53 and enters a standby state for determining the state of the release button.

  If the result of determination in step # 55 is that the 2R switch is on, the routine proceeds to step for shooting. First, a camera shake correction operation is started (# 57). This camera shake correction operation is performed by transmitting a camera shake correction operation start command to the camera shake correction controller 20 of the image stabilization mechanism 233. When the camera shake correction operation is started, the movable support member 27 (including the image sensor 221) is moved so as to reduce the motion of the camera shake based on the camera shake signal of the XY direction vibration sensor 21 as described above.

  Next, the live view operation is stopped (frozen) (# 59). Since the image data from the image sensor 221 is acquired during the exposure operation, the live view operation is stopped before entering the exposure operation.

  Subsequently, the lens CPU 111 is instructed to perform a narrowing operation (# 61). Now that the preparation for entering the imaging operation is completed, the exposure operation is started (# 63). In the exposure, the traveling of the front curtain of the shutter 213 is started and the charge accumulation of the image sensor 221 is started. When the time corresponding to the shutter speed obtained in step # 53 or the shutter speed manually set by the photographer has elapsed, the running of the rear curtain of the shutter 213 is started and the charge accumulation of the image sensor 221 is ended.

  When the exposure operation ends, the lens CPU 111 is instructed to open the aperture (# 65), and image processing is performed (# 67). In the image processing step, an image signal is read from the image sensor 221 and the image processing of the still image signal is performed by the image processing circuit 257 or the like. Once image processing has been carried out, the processed image data is then recorded on the recording medium 277 (# 69), and the recorded still image is displayed on the rear liquid crystal monitor 26 for a predetermined time (# 71). ).

  Next, the camera shake correction operation is stopped (# 73). The camera shake correction operation is stopped by transmitting a camera shake correction operation stop command to the camera shake correction controller 20 of the image stabilization mechanism 233. Subsequently, the camera shake correction mechanism is centered (# 75). This centering operation is performed by transmitting a centering operation command to the camera shake correction controller 20. When centering is performed, the live view operation is resumed (# 77), and the flow returns to the original flow.

  Next, the contrast AF subroutine of step # 51 will be described with reference to FIG. When the contrast AF subroutine is entered, camera shake detection is first started (# 101). In this step, acquisition of camera shake amount information based on a camera shake signal output from the XY direction vibration sensor 21 in the vibration isolation mechanism 233 is started.

  Subsequently, zoom information is acquired (# 103). In this step, zoom information related to the focal length detected by the zoom value detection mechanism 105 is acquired. Once the zoom information has been acquired, the AF area is set to the center position (# 105). In other words, as shown in FIG. 7A, an AF detection area 33 is set in the approximate center of the screen 31 as an area from which high-frequency components are extracted by the contrast AF processing circuit 253.

  When the AF area is set to the center position, the feeding direction is set as the lens driving direction (# 107). In the contrast AF method, the lens position at which the contrast information is the highest is obtained while moving the photographic lens. Therefore, in this step, the driving direction of the photographic lens 101 is set.

  Subsequently, 1 is set in the register DC (# 109). This register DC is a register used to determine the driving direction of lens driving. Thereafter, the contrast information in the AF area set in step # 105 is acquired from the contrast AF circuit 253 (# 111).

  When contrast information is acquired, lens driving is then started (# 113). In this step, a lens driving command is output to the lens CPU 111, and the lens driving mechanism 107 drives the photographing lens 101 in the extending direction. Subsequently, camera shake amount information is acquired (# 115). In this step, camera shake amount information output from the camera shake amount detection circuit 22 is acquired based on the camera shake signal of the XY direction vibration sensor 21 in the vibration isolation mechanism 233.

  When the camera shake amount is acquired, the movement amount of the AF detection area on the screen is calculated from the camera shake amount information and the zoom information (# 117). This movement amount will be described with reference to FIG. In the state where there is no camera shake, as shown in FIG. 6A, the subject luminous flux that has passed through the optical axis of the photographing lens 101 reaches the center position of the image sensor 221. For this reason, the AF detection area 33 is substantially at the center of the screen 31 as shown in FIG.

  However, as shown in FIG. 7B, when camera shake occurs, the range of the subject in the AF detection area 33 is different from the subject in FIG. 7A. This is because, as shown in FIG. 6B, the direction in which the photographic lens 101 faces due to camera shake differs from the state of FIG. 7A, and the light flux along the optical axis of the photographic lens 101. Arrive at different positions on the image sensor 221, that is, positions shifted by the amount of camera shake.

  Therefore, in order to obtain the same subject contrast information as when no camera shake occurs, the AF detection range 33 is set to the camera shake amount information and the zoom information acquired in step # 103 as shown in FIG. Move accordingly. Accordingly, since the contrast information of the same subject can always be obtained even if camera shake occurs, high-precision automatic focus adjustment can be performed.

  Next, it is determined whether or not the AF area is movable (# 119). That is, the AF detection area 33 can move only within the screen 31 corresponding to the image sensor 221. For this reason, when the AF detection area 33 is moved in accordance with the amount of camera shake, when the AF detection area 33 reaches the end of the screen 31, it cannot be moved any further. In step # 119, it is determined whether or not the AF detection area 33 has reached the screen 31 and can be moved.

  If the result of determination in step # 119 is that movement is possible, the AF detection area 33 is moved (# 121). On the other hand, if the result of determination is that it is not movable, the AF detection area 33 is fixed at the end. That is, as shown in FIG. 7D, the detection area 33 is fixed on the terminal side in the screen 31.

  Subsequently, contrast information is acquired in the reset AF detection area 33 (# 123). Next, it is determined whether or not the acquired contrast information has been improved (# 125). As described above, the contrast AF method is an automatic focus adjustment method in which the photographing lens 101 is moved to a position where the contrast value is maximized. Therefore, in this step, whether or not the contrast information is improved toward the maximum value. Determine.

  If the result of determination in step # 125 is that contrast information has improved, 1 is added to the register DC (# 143), and processing returns to step # 113. This is because, when it is determined that the contrast information is improved, the contrast information may be improved, and thus the photographing lens 101 is further driven in the same driving direction.

  If the result of determination in step # 125 is that contrast information has not improved, it is determined whether or not the register DC is 1 (# 127). If the result of this determination is that the register DC is 1, the lens drive direction is set to the carry-in direction (# 145), and the process returns to step # 113. In step # 107, when the lens driving direction is set to the feeding direction and the first driving is performed in this direction, the contrast information may be lowered. Therefore, in step # 127, it is determined whether or not the driving is the first time, and if it is the first time, the lens driving direction is reversed, the contrast information is acquired again, and the maximum position of this is searched. ing.

  If the result of determination in step # 127 is that register DC is not 1, lens drive is stopped (# 129). That is, since the contrast information is changed from an improvement to a decrease, and the register DC is not 1, it is determined that the contrast information has exceeded the maximum value, so that the driving of the photographing lens 101 is stopped.

  Subsequently, the lens is driven by a predetermined amount in the reverse direction of the previous time (# 131). In other words, since the contrast information exceeds the maximum value, it is returned by a predetermined amount toward the maximum value. Here, the predetermined amount may be appropriately determined as a design value, but may be, for example, about half of the driving amount per one time.

  When the lens is driven by a predetermined amount, focus display is performed (# 133). As the in-focus display, for example, a visual and aural in-focus display is performed in the optical viewfinder or the live view display screen. Subsequently, the camera shake detection started in step # 101 is terminated. When camera shake detection ends, the original flow is restored.

  Thus, in this embodiment, when performing contrast AF, the AF detection area (specific area) 33 is changed based on the amount of camera shake. For this reason, since contrast detection can be performed for the same portion of the subject even if camera shake occurs, it is possible to prevent the accuracy of contrast AF from being reduced due to camera shake and to prevent battery consumption.

  In the present embodiment, the camera shake correction operation is not performed when the contrast AF is executed. For this reason, it is possible to prevent power consumption for the camera shake correction operation. Further, in the present embodiment, when the AF detection area (specific area) 33 exceeds the movable range (# 119N), the AF detection area 33 is fixed at the end. For this reason, although there is a possibility that the accuracy is lowered, the automatic focus adjustment by the contrast AF can be continued. Further, in the present embodiment, in the case of a zoom lens, zoom information is acquired and the movement amount of the AF detection area 33 is calculated (# 117). For this reason, even with a zoom lens, contrast AF can be performed with high accuracy.

  In the present embodiment, the camera shake correction operation is a method of moving the image sensor 221 according to the amount of camera shake. However, other anti-vibration methods may be used. For example, an anti-vibration optical system is provided in the photographing lens 101 and the anti-vibration optical system is driven so as to cancel camera shake, or an image output from the image sensor 221. An image processing method may be used so that the position at which data is cut out according to the amount of camera shake is changed.

  Furthermore, in the present embodiment, an example in which the present invention is applied to a compact digital camera has been described. However, the present invention is not limited to this, and a digital single-lens reflex camera may be used, and an imaging apparatus that is incorporated in a mobile phone, a PDA, or the like. Of course, the present invention can also be applied.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the gist thereof in the implementation stage. . In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, you may delete some components of all the components shown by embodiment.

1 is a block diagram illustrating an overall configuration mainly including an electric system of a digital camera according to an embodiment of the present invention. It is a block diagram which shows the structure relevant to the vibration proof operation in one Embodiment of this invention. It is a flowchart which shows the operation | movement of the power-on reset in the camera main body side in one Embodiment of this invention. It is a flowchart which shows the imaging | photography operation | movement in one Embodiment of this invention. It is a flowchart which shows the operation | movement of contrast AF in one Embodiment of this invention. FIG. 6 is a diagram for explaining a change in imaging position in the presence or absence of a camera shake state in an embodiment of the present invention. FIG. 6 is a diagram illustrating a camera shake state and movement of an AF detection area in an embodiment of the present invention.

Explanation of symbols

20 ... shake controller, 21 ... XY direction vibration sensor, 22 ... hand shake amount detection circuit, 23 ... drive mechanism, 24 ... position detection sensor, 26 ... back LCD monitor, 27 ..Moving support member, 31... Screen, 33... AF detection area, 100... Interchangeable lens, 101. ... Lens drive mechanism, 109 ... Aperture drive mechanism, 111 ... Lens CPU, 200 ... Camera body, 213 ... Focal plane shutter, 215 ... Dustproof filter, 216 ... Piezoelectric element 217: Infrared cut filter / low pass filter, 219: Imaging unit, 221 ... Imaging device, 223 ... Imaging device drive circuit, 225 ... Pre-processing circuit, 2 3 ... Anti-vibration mechanism, 235 ... Dust-proof filter drive circuit, 237 ... Shutter drive mechanism, 250 ... ASIC, 251 ... Sequence controller (body CPU), 252 ... Data bus, 253 ... Contrast AF circuit, 257 ... Image processing circuit, 259 ... Compression / decompression circuit, 261 ... Video signal output circuit, 263 ... Liquid crystal monitor drive circuit, 265 ... SDRAM detection circuit, 267 ... SDRAM, 271 ... I / O circuit, 273 ... Communication circuit, 275 ... Recording medium control circuit, 277 ... Recording medium, 279 ... Flash memory control circuit, 281 ... Flash Memory, 283 ... switch detection circuit, 285 ... various switches, 287 ... attachment / detachment detection switch, 291 ... communication contact

Claims (5)

An imaging unit that captures a subject image via a photographic lens and outputs an image signal;
A contrast detection unit for detecting a contrast value for the specific region of the image signal;
An AF control unit that adjusts the focus of the photographing lens so that the contrast value is maximized;
A camera shake detection unit for detecting a camera shake amount;
It has
The imaging apparatus according to claim 1, wherein the contrast detection unit changes the specific area based on the amount of camera shake.   A camera shake correction unit that performs a camera shake correction operation that cancels camera shake applied to the imaging device based on the camera shake amount, and the camera shake correction is performed while the AF control unit performs focus adjustment of the photographing lens. The imaging apparatus according to claim 1, wherein the camera shake correction operation by the unit is prohibited.   A determination unit that determines whether or not the specific region exceeds a changeable range, and when the determination unit determines that the specific region exceeds a changeable range, the contrast detection unit The imaging apparatus according to claim 1, wherein the specific area is fixed.   The photographing lens is a variable focal length lens, the imaging device further includes a focal length detection mechanism that detects focal length information of the photographing lens, and the contrast detection unit includes the focus in addition to the information on the amount of camera shake. The imaging apparatus according to claim 1, wherein the specific area is changed based on distance information. In a control method of an imaging apparatus capable of detecting a contrast value for a specific region of an image signal output from an imaging element and performing a contrast AF operation for adjusting a focus of a photographing lens so that the contrast value is maximized,
A method for controlling an imaging apparatus, comprising: detecting a camera shake amount generated during execution of the contrast AF operation, and changing the specific region according to the camera shake amount.