JP2012118153A - Automatic focus adjustment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the problem of an AF evaluation value not being made maximum in a focused state by having an abnormal way of variation in the AF evaluation value due to an area of reflected light of illumination light on imaging means becoming different according to the state of focus adjustment means when a position for acquiring the AF evaluation value and an illuminating position for an illumination device are not matched.SOLUTION: An automatic focus adjustment device includes: imaging means for acquiring an electrical image signal by carrying out a photo-electric conversion on a subject image formed by a photographic optical system; focus adjustment means for adjusting the focus of the subject image formed on the imaging means; focal position detection means for detecting the focal position from image signals from one portion of the imaging means that is generated by the imaging means while driving the focal adjustment means; illumination means for illuminating the whole or a portion of the subject when the AF evaluation value is acquired; and means for detecting the illuminating position of the illumination means. In this case, illumination by the illumination means is not carried out when the illuminating position of the illumination means is not matched with one portion of the imaging means for acquiring the signal that is used for detecting the focal position.

Description

  The present invention relates to an automatic focus adjustment device, and more particularly to an automatic focus adjustment device that performs focus adjustment using an image signal acquired by an image sensor that photoelectrically converts a subject image formed by an imaging optical system. .

  In conventional automatic focus adjustment (AF), there are Patent Document 1 and Patent Document 2 regarding coping methods when the main subject position and the illumination position of the illumination means do not match.

JP 2008-216828 JP 2003-114375 A

  Patent Document 1 has the following description.

  Appropriate focus adjustment of the photographic lens regardless of the face position. When the shutter button is half-pressed, the face extraction circuit starts extracting a face area from the image. When the face area is extracted, the CPU drives the stepping motor via the motor driver, directs the LED auxiliary light irradiation direction toward the face of the subject, and emits auxiliary light from the LED via the LED driver. The auxiliary light is applied to the face of the subject to increase the contrast between the face area and the surrounding area. The AF detection circuit performs focus control using a face area having a high contrast with the surroundings as a focus evaluation area, and determines a focus position of the focus lens. Based on the focus position determined by the AF detection circuit, the CPU drives the focus lens motor via the motor driver to move the focus lens to the focus position and adjust the focus. Shooting is performed by pressing the shutter button fully, and digital data is stored.

  Patent Document 2 has the following description.

  An image pickup apparatus having a zoom function and including an auxiliary light device that illuminates a subject for focus detection can perform stable and highly accurate automatic focus adjustment. Illumination light from a light-emitting diode as an auxiliary light device that moves a distance measuring frame for focus detection according to the focal length of the zoom lens device and illuminates a subject for focus detection by a control unit of the drive control circuit Based on the focus detection, the focus detection in the distance measurement frame is performed, and the zoom lens device is performed based on the detected focus detection information.

  However, in the above-mentioned Patent Document 1, there are problems that a cost increases due to provision of a member for driving the illumination means (LED), the size of the device is increased, and a release time lag is generated due to time required for driving.

  Further, in Patent Document 2, there is a problem that moving the distance measuring frame does not focus on the subject intended by the photographer.

  When the position where the AF evaluation value is acquired and the illumination position of the illuminating device are not matched as in the conventional example, the illumination light illuminated by the illuminating device may be reflected to something other than the main subject such as a back wall. In this case, the area of the reflected light on the imaging unit differs depending on the state of the focus adjustment unit, and depending on the relationship between the position where the AF evaluation value is acquired and the illumination position of the illumination unit, the AF evaluation value is gradually increased as the focus adjustment unit is driven. Reflected light may enter the area to be acquired, or may gradually exit. As a result, the manner in which the AF evaluation value changes becomes abnormal, and the AF evaluation value may not be maximized in a focused state. That is, when the reflected light gradually enters the range in which the AF evaluation value is acquired as the focus adjustment unit is driven, the contrast of the image increases due to the reflected light, and the image becomes blurred. In some cases, the AF evaluation value may increase. On the other hand, when the light gradually comes out, the contrast of the image is lowered due to the reflected light coming out, and the AF evaluation value may become small despite being focused.

In contrast, in the present invention,
While driving an imaging unit that photoelectrically converts a subject image formed by the photographing optical system to obtain an electrical image signal, a focus adjustment unit that adjusts the focus of the subject image formed on the imaging unit, and a focus adjustment unit while driving In-focus position detecting means for detecting the in-focus position from a part of the image signal of the imaging means generated by the imaging means, illuminating means for illuminating all or part of the subject when obtaining the AF evaluation value, illumination of the illuminating means In an automatic focusing apparatus having means for detecting a position,
When the illumination position of the illumination unit does not coincide with a part of the imaging unit that acquires a signal used when detecting the in-focus position, illumination by the illumination unit is not performed.

  In the present invention, when the illumination position of the illumination unit does not coincide with a part of the imaging unit that acquires a signal used when detecting the in-focus position, the illumination unit does not perform illumination.

  As a result, the illumination light illuminated by the illumination device is reflected by things other than the main subject, such as a wall behind the main subject, etc., so that the reflected light falls within a range where the AF evaluation value is gradually acquired as the focus adjustment unit is driven. In this case, it is possible to prevent the AF evaluation value from changing abnormally and not to be maximized in a focused state.

Example 1 and 2 block diagram Explanatory drawing of the operation procedure of Example 1. Explanatory drawing of the operation procedure of Example 1. Explanatory drawing of the scan AF operation of Embodiments 1 Explanatory drawing of the operation | movement procedure of Example 2. FIG. Explanatory drawing of the operation procedure of AF before SW1 of Example 2

[Example 1]
FIG. 1 shows a block diagram of an embodiment of the present invention.

  Reference numeral 1 denotes an imaging device, 2 denotes a zoom lens group, 3 denotes a focus lens group, 4 denotes a zoom lens group, 2 a focus lens group 3 and the like. A diaphragm 31, a zoom lens group 2, a focus lens group 3, a diaphragm 4, and the like, and a solid image pickup device (hereinafter referred to as a CCD) that forms a subject image that has passed through the photographing optical system and photoelectrically converts the image. , 6 receives an electrical signal photoelectrically converted by the CCD 5 and performs various image processing to generate a predetermined image signal, and 7 denotes an analog image signal generated by the imaging circuit 6 as a digital image signal. An A / D conversion circuit 8 that changes into a memory (VRAM) such as a buffer memory that receives the output of the A / D conversion circuit 7 and temporarily stores the image signal; A D / A conversion circuit for reading out an image signal stored in the VRAM 8 and converting it into an analog signal and converting it into an image signal in a form suitable for reproduction output, a liquid crystal display device (LCD) for displaying the image signal An image display device (hereinafter referred to as an LCD) such as a storage memory 12 for storing image data such as a semiconductor memory, and 11 is a form suitable for storage in the storage memory 12 by reading out an image signal temporarily stored in the VRAM 8. A compression circuit for compressing and encoding image data and a decoding process and an expansion process for making the image data stored in the storage memory 12 optimal for reproducing and displaying the image data. A compression / expansion circuit composed of an expansion circuit to be applied; 13 an AE processing circuit for receiving an output from the A / D conversion circuit 7 and performing an automatic exposure (AE) process; A scan AF processing circuit that receives an output from the A / D conversion circuit 7 that is an F evaluation value generation unit and performs an automatic focus adjustment (AF) process, and a CPU that includes a calculation memory that controls the imaging apparatus, 16 is a timing generator (hereinafter referred to as TG) for generating a predetermined timing signal, 17 is a CCD driver, 21 is a diaphragm drive motor for driving the diaphragm 4, 18 is a first motor drive circuit for driving and controlling the diaphragm drive motor 21, and 22 is A focus drive motor for driving the focus lens group 3, a second motor drive circuit for driving and controlling the focus drive motor 22, a zoom drive motor for driving the zoom lens group 2, and a drive control for the zoom drive motor 23. Third motor drive circuit, 24 is an operation switch composed of various switch groups, and 25 is a program for performing various controls. EEPROM, which is an electrically rewritable read-only memory in which data and the like used for performing various operations are stored in advance, 26 is a battery, 28 is a flash emission unit, 27 is a flash of the flash emission unit 28 A switching circuit that controls light emission, 29 is a display element such as an LED that displays warnings, 30 is a speaker for performing voice guidance and warnings, and 33 is all or part of a subject when acquiring AF evaluation values AF auxiliary light composed of a light source such as an LED, which is an illumination means for illuminating the light, 32 is an AF auxiliary light driving circuit for driving the AF auxiliary light 33, 35 is a shake detection sensor for detecting camera shake, and 34 is a shake. A shake detection circuit 36 that processes a signal from the detection sensor 35 receives an output from the A / D conversion circuit 7 and receives a face position and face size on the screen. Etc. is a face detection circuit for detecting a.

  The storage memory, which is a storage medium for image data or the like, is a fixed semiconductor memory such as a flash memory, or a semiconductor such as a card type flash memory that has a card shape or stick shape and is detachable from the device. In addition to the memory, various forms such as a magnetic storage medium such as a hard disk or a floppy disk are applied.

  The operation switch 24 includes a main power switch for starting the imaging apparatus 1 to supply power, a release switch for starting a photographing operation (storage operation), a reproducing switch for starting a reproducing operation, and a photographing optical system. There are a zoom switch for moving the zoom lens group 2 to perform zooming, an optical viewfinder (OVF) electronic viewfinder (EVF) changeover switch, and the like.

  The release switch then performs a first stroke (hereinafter referred to as SW1) for generating an instruction signal for starting AE processing and AF processing performed prior to the photographing operation and a second stroke (hereinafter referred to as SW2) for generating an instruction signal for starting an actual exposure operation. And a two-stage switch.

  The operation of this embodiment configured as described above will be described below.

  First, the light flux of the subject that has passed through the taking lens barrel 31 of the image pickup apparatus 1 is adjusted on the light amount by the diaphragm 4 and then imaged on the light receiving surface of the CCD 5. This subject image is converted into an electrical signal by photoelectric conversion processing by the CCD 5 and output to the imaging circuit 6. In the imaging circuit 6, various signal processing is performed on the input signal, and a predetermined image signal is generated. The image signal is output to the A / D conversion circuit 7 and converted into a digital signal (image data), and then temporarily stored in the VRAM 8. The image data stored in the VRAM 8 is output to the D / A conversion circuit 9, converted into an analog signal, converted into an image signal in a form suitable for display, and then displayed as an image on the LCD. On the other hand, the image data stored in the VRAM 8 is also output to the compression / decompression circuit 11. After compression processing is performed by the compression circuit in the compression / decompression circuit 11, it is converted into image data in a form suitable for storage and stored in the storage memory 12.

  Also. For example, when a reproduction switch (not shown) of the operation switches 24 is operated and turned on, the reproduction operation is started. Then, the image data stored in a compressed form in the storage memory 12 is output to the compression / expansion circuit 11, subjected to decoding processing, expansion processing, etc. in the expansion circuit, and then output to the VRAM 8 and temporarily stored. The Further, the image data is output to the D / A conversion circuit 9, converted into an analog signal, converted into an image signal in a form suitable for display, and then displayed on the LCD 10 as an image.

  On the other hand, the image data digitized by the A / D conversion circuit 7 is output to the AE processing circuit 13, the scan AF processing circuit 14, and the face detection circuit 36 separately from the VRAM 8 described above. First, the AE processing circuit 13 receives the input digital image signal and performs arithmetic processing such as cumulative addition on the luminance value of the image data for one screen. Thereby, the AE evaluation value corresponding to the brightness of the subject is calculated. This AE evaluation value is output to the CPU 15.

  The scan AF processing circuit 14 receives the input digital image signal, extracts high-frequency components of the image data through a high-pass filter (HPF) or the like, and performs arithmetic processing such as cumulative addition, AF evaluation value signals corresponding to the contour component amounts and the like are calculated. Specifically, in the scan AF process, a high-frequency component of image data corresponding to a partial area of the screen designated as an AF area is extracted through a high-pass filter (HPF) or the like, and an arithmetic process such as cumulative addition is performed. Thereby, an AF evaluation value signal corresponding to the contour component amount on the high frequency side and the like is calculated. This AF area may be a single location in the central portion, a central portion and a plurality of locations adjacent thereto, or a plurality of locations distributed discretely.

  As described above, the scan AF processing circuit 14 plays a role of high-frequency component detection means for detecting a predetermined high-frequency component from the image signal generated by the CCD 5 in the process of performing the AF processing.

  The face detection circuit 36 receives the input digital image signal, searches the image for a part characterizing the face such as eyes and eyebrows, and obtains the position of the person's face on the image. Further, the size and inclination of the face are obtained from the positional relationship such as the interval between the parts characterizing the face.

  On the other hand, a predetermined timing signal is output from the TG 16 to the CPU 15, the imaging circuit 6, and the CCD driver 17, and the CPU 15 performs various controls in synchronization with this timing signal. The imaging circuit 6 receives the timing signal from the TG 16 and performs various image processing such as separation of color signals in synchronization with the timing signal. Further, the CCD driver 17 receives the timing signal of the TG 16 and drives the CCD 5 in synchronization therewith.

  Further, the CPU 15 controls the first motor driving circuit 18, the second motor driving circuit 19, and the third motor driving circuit 20, respectively, so that the diaphragm 4 via the diaphragm driving motor 21, the focus driving motor 22, and the zoom driving motor 23 is controlled. The focus lens group 3 and the zoom lens group 2 are driven and controlled. That is, the CPU 15 controls the first motor drive circuit 18 based on the AE evaluation value calculated in the AE processing circuit 13 to drive the aperture drive motor 21 and adjust the aperture amount of the aperture 4 so as to be appropriate. I do. Further, the CPU 15 controls the second motor drive circuit 19 based on the AF evaluation value signal calculated by the scan AF processing circuit 14 to drive the focus drive motor 22 and performs AF control to move the focus lens group 3 to the in-focus position. . When a zoom switch (not shown) among the operation switches 24 is operated, the CPU 15 moves the zoom lens group 2 by controlling the third motor drive circuit 20 and driving the zoom motor 23 in response to the operation. Then, the zooming operation of the photographing optical system is performed.

  Next, the actual photographing operation of the imaging apparatus will be described with reference to the flowcharts shown in FIGS.

  In the description of the present invention, the operation of acquiring the AF evaluation value while driving the focus lens group 3 to a predetermined position is scanned, the interval of the position of the focus lens for acquiring the AF evaluation value is the scan interval, and the AF evaluation value is acquired. The number to be scanned is referred to as the number of scan points, and the range in which the AF evaluation value is acquired is referred to as the scan range.

  When the main power switch of the image pickup apparatus 1 is in the on state and the operation mode of the image pickup apparatus is in the shooting (recording) mode, a shooting process sequence is executed and imaging is possible by supplying power to the CCD 5 or the like. To.

  First, in step S201, the CPU 15 performs AE. In other words, the exposure amount of the CCD 5 is optimized based on the AE evaluation value corresponding to the brightness of the subject that has been arithmetically processed in the AE processing circuit 13.

  Next, in step S202, face detection is performed to determine the position on the screen of the face of the person who is the main subject and the size of the face.

  In step S203, the distance from the face size obtained in step S202 to the main subject is estimated, and the screen is determined from the estimated distance and the interval (parallax) between the photographic lens barrel 31 and the AF auxiliary light 33. The illumination position of the AF auxiliary light 33 is estimated.

This series of operations (steps S201 to S203) is repeated until SW1 is turned on.
If it is determined in step S204 that SW1 has been turned on, it is determined in step S205 whether face detection has succeeded in a series of previous operations.

  If the face detection is successful, the process proceeds to step S206. If the face detection is not successful, the process proceeds to step S221.

In step S206, the distance to the main subject estimated in step S203 is compared with a predetermined distance. If the distance is longer than the predetermined distance, the process proceeds to step S210, and the AF auxiliary light is turned off. As a result, it is possible to eliminate the waste of lighting the AF auxiliary light for a subject at a long distance where the AF auxiliary light does not reach.
When the distance is shorter than the predetermined distance, the process proceeds to step S207, and it is determined whether or not the AF auxiliary light 33 is illuminated at the position on the screen of the face detected in step S202.

  The illumination range of the AF auxiliary light 33 has a certain extent, and the size thereof varies depending on the subject distance. Since the irradiation angle is constant, it increases as the distance increases. Further, the AF area (a part of the image pickup means for acquiring a signal used when detecting the in-focus position) is determined by the position / size of the face detected in step S202. If the overlap of the illumination range of the AF auxiliary light 33 and the AF area on the screen is a predetermined value or more, it is determined that the AF auxiliary light 33 is illuminated at the face position.

  This predetermined value is given by multiplying a certain ratio with respect to the AF area. For example, when the areas on the screen that are 50% or more of the AF area overlap, it is determined that the AF auxiliary light 33 is illuminated at the face position. However, when the AF area is large, there may be a case where the predetermined ratio is not satisfied even if the illumination range of the AF auxiliary light 33 is entirely within the AF area, so an upper limit is provided. When the area on the screen equal to or greater than a predetermined ratio (for example, 50%) of the AF area exceeds the predetermined area, the predetermined area is used for determining whether the AF auxiliary light 33 is illuminated at the face position. And

  If it is determined in step S207 that the AF auxiliary light 33 is illuminated at the face position, the process proceeds to step S208, the AF auxiliary light 33 is turned on, and in this state, AE is performed in step S209 to obtain an AE evaluation value. Then, in step S211, an exposure value for the scan AF performed in step S212 is determined.

  On the other hand, if it is determined in step S207 that the AF auxiliary light 33 is not illuminated at the face position, the setting of the AF auxiliary light 33 during the scan AF in step S212 is turned off in step S210, and then the process proceeds to step S211. Based on the AE evaluation value acquired in step S201, the exposure value for the scan AF performed in step S212 is determined.

In step S212, scan AF is performed, and the result is displayed in step S213.
An outline of scan AF processing and result display for detecting the in-focus position performed in steps S212 and S213 will be described.

  Scan AF is performed by obtaining the position of the focus lens group 3 where the high-frequency component output from the image signal generated by the CCD 5 is the largest. The CPU 15 controls the focus drive motor 22 via the second motor drive circuit 19 that controls the drive of the focus drive motor 22, and moves the focus lens group 3 to the scan start position (“A4” in FIG. 4 corresponding to infinity in the case of full range scan). When the position and range are limited, the scan end position set in each shooting mode from the positions “A1”, “A2”, and “A3” in FIG. In the case of limiting the position and range “B4” in FIG. 4 corresponding to the distance, driving is performed up to the positions “B1”, “B2”, and “B3” in FIG. 4 corresponding to each range). Then, the output of the scan AF processing circuit (AF evaluation value signal) is acquired while driving, and the position where the output becomes maximum from the AF evaluation value signal acquired when the driving of the focus lens group 3 is completed (see “ C ") is obtained, and the focus lens group 3 is driven to that position.

  The acquisition of the output of the AF processing circuit is not performed at all the stop positions of the focus lens group 3 but at predetermined steps for speeding up the scan AF. In this case, the AF evaluation value signal may be acquired at points a1, a2, and a3 shown in FIG. In such a case, the in-focus position C is obtained by calculation from the point at which the AF evaluation value signal becomes the maximum value and the points before and after the point. Interpolation calculation is performed in this way, and the reliability of the AF evaluation value signal is evaluated before obtaining the point at which the AF evaluation value signal has the maximum value (C in FIG. 4). If the reliability is sufficient, a point at which the AF evaluation value signal becomes the maximum value is obtained. If the reliability of the AF evaluation value signal is low as a result of the evaluation, the lens is placed at an appropriate position within a scanning range called a fixed point without performing processing for obtaining a point at which the AF evaluation value signal is maximum. Control.

Further, AFOK display or AFNG display is performed according to the result of reliability evaluation. When the reliability is sufficient, AFOK display is performed by turning on the display element 29 or displaying a green frame on the LCD.
If the reliability of the AF evaluation value signal is evaluated and the reliability is low, AFNG display is performed by blinking the display element 29 or displaying a yellow frame on the LCD.

  The focus determination performed here is performed by determining whether or not the acquired AF evaluation value has a mountain shape and the peak can be detected. Details are described in Japanese Patent Application Laid-Open No. 2004-101766, and will not be described.

  Thereafter, in step S214, it waits for SW2 to be turned on and a release operation is requested. If SW2 is turned on, exposure processing is performed in step S215.

  On the other hand, if it is determined in step S205 that face detection has not been successful in a series of previous operations and the process proceeds to step S221, it is first checked in step S221 whether the AiAF mode is set. In the AiAF mode, a plurality of AF areas are provided, an AF evaluation value is acquired while driving the focus lens group 3 in each AF area, and the position of the focus lens group 3 at which the AF evaluation value is maximized is obtained. The optimum AF area is selected from the position of the focus lens group 3 that maximizes the AF evaluation value, and the position of the focus lens group 3 that maximizes the AF evaluation value of the AF area is set as the in-focus position. This is an AF mode that can prevent a failure in which the background is out of focus when there is no main subject in the center of the screen.

  If the AiAF mode is set, the process proceeds from step S221 to step S208, and the AF auxiliary light 33 is turned on. The following processing is as described above.

  If the AiAF mode is not set, that is, if the one-point AF mode is set, the process proceeds to step S222. In the one-point AF mode, the AF area may be set at the center or may be set at an arbitrary position on the screen. The subsequent processing is the same.

  First, in step S222, an image with the AF auxiliary light 33 turned off is acquired.

  Next, in step S223, the AF auxiliary light 33 is turned on, and an on-state image is acquired in step S224.

  In step S225, a difference image between the image in which the AF auxiliary light 33 is on and the image in the off state is obtained. From this image, the illumination position of the AF auxiliary light 33 is obtained in step S226. The portion where the output value of the difference image is large is the illumination position of the AF auxiliary light 33.

  If the illumination position of the AF auxiliary light 33 cannot be obtained, the process proceeds from step S227 to step S229, and the AF auxiliary light 33 is turned off. Thereafter, the process proceeds to step S211. The following processing is as described above.

  If the illumination position of the AF auxiliary light 33 is obtained, it is determined in step S228 whether the AF auxiliary light 33 is illuminated in the AF area. The method of determination is the same as in step S207. However, the difference is that the size of the AF area is constant in the one-point AF mode. When the AF auxiliary light 33 is illuminated in the AF area, the process proceeds from step S228 to step S208, and the AF auxiliary light 33 is turned on. The following processing is as described above. When the AF auxiliary light 33 is not illuminated in the AF area, the process proceeds from step S228 to step S229, and the AF auxiliary light 33 is turned off. Thereafter, the process proceeds to step S211. The following processing is as described above.

  By doing so, the illumination light illuminated by the AF auxiliary light 33 is reflected on a wall other than the main subject such as a wall behind the main subject, etc., so that the AF evaluation value gradually increases as the focus adjustment unit is driven. So that the reflected light does not enter the area where the image is acquired or the light gradually exits. This makes the AF evaluation value change abnormally and maximizes it in focus. It is possible to prevent harmful effects such as not becoming necessary.

[Example 2]
The difference between the second embodiment of the present invention and the first embodiment is that focus adjustment (scan AF) is performed before the switch SW1 is turned on, the distance to the subject is known from the result, and illumination by the AF auxiliary light 33 is performed at a long distance. It is a point not to do. In the scan AF before SW1, illumination with the AF auxiliary light 33 is not performed. Another difference is that the illumination with the AF auxiliary light 33 is not performed when the illuminance (brightness) at the position corresponding to the face position obtained from the result of the face detection means is brighter than a predetermined value.

  FIG. 5 shows the procedure. The description of the same parts as those in the first embodiment is omitted.

  In step S401, pre-SW1 AF is performed. In this AF, since the focus change accompanying AF is displayed on the LCD 10, it is necessary to suppress the change amount.

  The content of the pre-SW1 AF will be described with reference to FIG.

  First, in step S501, it is checked whether or not the pre-SW1 AF is executed immediately after activation (the imaging process sequence is executed). In the case of pre-SW1 AF immediately after activation, the process proceeds to step S502, and the focus lens group 3 is moved to the overfocus position. To do. In step S503, the lens stop flag is cleared.

  On the other hand, if it is not the pre-SW1 AF immediately after the activation (the pre-SW1 AF has already been executed), the process proceeds to step S504 to check whether the lens stop flag is set.

  If the lens stop flag is not set, the process proceeds to step S505 to perform a 5-point scan. This is a scan AF that acquires five AF evaluation values, and the scan is performed in a very small scan range. For example, a range from A1 to B1 shown in FIG. 4 is scanned. For example, the scan interval is set to about 5 times or less of the open depth at the zoom position. Except that the scan range is limited, it is the same as the scan AF in step S212 of FIG.

  Next, it is determined whether or not the focus is achieved by the five-point scan in the minute range. If the focus is achieved, the process proceeds to step S507 and the lens stop flag is set.

  In step S508, it is checked whether or not a luminance change has occurred. This is to calculate the cumulative addition calculation value of the luminance value in the area corresponding to the AF area of the CCD, and to calculate the luminance value in the area corresponding to the AF area of the CCD calculated when the previous SW1 pre-AF is performed. This is done by comparing with the cumulative addition operation value. That is, the absolute value of the difference between the calculated cumulative addition calculation value and the previous cumulative addition calculation value is obtained, and when the value exceeds a predetermined value, it is determined that a luminance change has occurred. To clear.

  If there is no change in luminance, the process proceeds to step S509 to check for panning. This is done by reading the output of the shake detection sensor 35 via the shake detection circuit 34 and comparing the value with a predetermined value. An angular velocity sensor called a vibration gyro is generally used as the shake detection sensor. Two vibrating gyros are used in directions orthogonal to each other, and are configured to obtain two-axis angular velocities in the pitch direction and the yaw direction. The output of the shake detection sensor 35 (vibration gyro) is input to the shake detection circuit 34 and converted into angular displacement by the shake detection circuit 34. In the check of panning occurrence, this angular displacement is cumulatively calculated for each pitch direction and yaw direction, and it is determined that panning has occurred when any of the accumulated values exceeds a predetermined value, the process proceeds to step S510, and the lens stop flag is set. To clear. Thereafter, the sub-module is exited and the process proceeds to step S202 in FIG.

  If neither brightness change nor panning occurs, the process leaves the submodule and proceeds to step S202 in FIG.

  A motion vector may be used for checking panning occurrence. As is well known, the motion vector is a method of detecting the amount of motion in the image of the target portion of the image in units of pixels by performing a correlation operation between the previous and subsequent images. A motion vector is obtained, and it is determined that panning has occurred if the integrated value of the motion vectors exceeds a predetermined value.

  On the other hand, if it is determined in step S506 that the image is out of focus, the process proceeds to step S520, and the scan range is changed. This is for obtaining the focus in the next or subsequent AF before SW1 AF, and differs depending on whether the in-focus position is at infinity side or near side and when it is known from the 5-point scan in step S505. If the direction in which the in-focus position exists is known, the scan range is shifted in that direction. For example, when it is found that the in-focus position is on the near side, the scan range is changed so that the scan point at the end on the near side before the change becomes the scan point at the center of the next scan. If the direction in which the in-focus position exists is not known, the scan range is shifted to the closest side. The scan range is changed so that the scan point at the end on the near side before the change becomes the scan point at the end on the infinity side of the next scan. However, if it cannot be shifted to the nearest side, shift to the infinity side. The scan range is changed so that the scan point at the end on the infinity side before the change becomes the scan point at the end on the near side of the next scan. Thereafter, the sub-module is exited and the process proceeds to step S202 in FIG.

  In step S402, the result of the pre-SW1 AF is received, and it is checked whether the distance to the subject is greater than a predetermined distance. If it is longer than the predetermined distance, the process proceeds to step S210, and if it is closer than the predetermined distance, the process proceeds to step S205. In either case, the subsequent processing is the same as in the first embodiment. If the distance to the subject cannot be obtained because the pre-SW1 AF is not in focus, the process proceeds to step S205 to determine whether to perform illumination with the AF auxiliary light 33 using other conditions.

  If it is determined in step S207 that the AF assist light 33 is illuminated at the face position, the process proceeds to step S403, and whether the brightness (illuminance) of the face position obtained by the face detection circuit 36 is brighter than a predetermined brightness. Determine whether or not.

  If it is determined in step S403 that the brightness at the face position is brighter than the predetermined brightness, the setting of the AF auxiliary light 33 during scan AF in step S210 is turned off in step S210, and then the process proceeds to step S211 and is already performed. Based on the AE evaluation value acquired in S201, the exposure value for the scan AF performed in step S212 is determined.

  On the other hand, if it is not determined in step S403 that the brightness at the face position is brighter than the predetermined brightness, the process proceeds to step S208, the AF auxiliary light 33 is turned on, and in this state, AE is performed in step S209, and the AE evaluation value After that, in step S211, an exposure value for the scan AF performed in step S212 is determined.

  In addition, the scan range of the scan AF performed in step S212 changes according to the result of the pre-SW1 AF performed in step S401.

  If the result of AF before SW1 is in-focus and no luminance change or panning occurs thereafter, the 5-point scan performed in step S505 is performed. In other cases, the same operation as the scan AF of the first embodiment is performed.

  By doing so, the illumination light illuminated by the AF auxiliary light 33 is reflected on a wall other than the main subject such as a wall behind the main subject, etc., so that the AF evaluation value gradually increases as the focus adjustment unit is driven. So that the reflected light does not enter the area where the image is acquired or the light gradually exits. This makes the AF evaluation value change abnormally and maximizes it in focus. It is possible to prevent harmful effects such as not becoming necessary. At the same time, the release lime lag can be shortened when the focus is obtained by the pre-SW1 AF.

  Although the first and second embodiments have been described by taking a compact digital camera as an example, the present invention can be applied to a digital video camera or AF during digital live view.

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Zoom lens group 3 Focus lens group 4 Aperture 31 Shooting lens barrel 5 Solid-state image sensor (CCD)
6 Imaging circuit 7 A / D conversion circuit 8 Memory such as buffer memory (VRAM) for temporarily storing image signals
9 D / A conversion circuit 10 Image display device 12 such as a liquid crystal display (LCD) 12 Storage memory 11 for storing image data The image data temporarily stored in the VRAM 8 is read and the image data is compressed in the storage memory 12 Compression / decompression circuit 13 AE processing circuit 14 Scan AF processing circuit 15 CPU with built-in memory for calculation comprising compression circuit for performing encoding processing and expansion circuit for performing decoding processing, expansion processing, etc.
16 Timing generator 17 CCD driver 21 Aperture drive motor 18 First motor drive circuit 22 for driving and controlling the aperture drive motor 21 Focus drive motor 19 for driving A second motor drive circuit 23 for driving and controlling the focus drive motor 22 Zoom drive motor 20 Zoom drive Third motor drive circuit 24 for driving the motor 23 Operation switch 25 EEPROM
26 Battery 28 Strobe light emitting unit 27 Switching circuit 29 for controlling flash emission 29 Display element 30 such as LED for warning display etc. Speaker 32 for voice guidance and warning etc. AF auxiliary light for driving AF auxiliary light 32 Drive circuit 33 AF auxiliary light 34 shake detection circuit 35 shake detection sensor 36 face detection circuit

Claims (9)

While driving an imaging unit that photoelectrically converts a subject image formed by the photographing optical system to obtain an electrical image signal, a focus adjustment unit that adjusts the focus of the subject image formed on the imaging unit, and a focus adjustment unit while driving Focus position detection means for detecting a focus position from a part of the image signal of the image pickup means generated by the image pickup means, and illuminating all or part of the subject when acquiring the image signal for detecting the focus position In an automatic focusing apparatus having an illumination means and a means for detecting an illumination position of the illumination means,
An automatic focus adjustment apparatus characterized in that when the illumination position of the illumination means does not coincide with a part of the imaging means for acquiring a signal used for detecting the in-focus position, the illumination means is not illuminated. 2. The automatic focus adjustment apparatus according to claim 1, wherein the exposure amount of the image pickup means when acquiring the image signal for detecting the in-focus position is adjusted in a state where the illumination is turned on. When the overlap of a part of the image pickup means for acquiring a signal used for detecting the illumination range and the focus position of the illumination means is equal to or less than a predetermined ratio of a part of the image pickup means, the illumination position of the illumination means detects the focus position. The automatic focus adjustment apparatus according to claim 1, wherein the automatic focus adjustment apparatus is regarded not to coincide with a part of an imaging unit that acquires a signal to be used at the time. A face detecting means for detecting the face position and the face size on the image pickup means, estimating the distance to the subject from the detected face size, and further from the parallax of the lighting means and the photographing optical system The automatic focus adjustment apparatus according to claim 1, wherein an illumination position on the imaging unit of the illumination unit is detected. 5. The illumination means is not illuminated when acquiring an image signal for detecting the in-focus position when the distance to the subject estimated by the size of the detected face is greater than a predetermined distance. The automatic focusing device described in 1. Detecting the illumination position on the imaging means of the illumination means from the difference signal between the image signal obtained by the imaging means when illuminated by the illumination means and the image signal obtained by the imaging means when not illuminated by the illumination means The automatic focus adjustment apparatus according to claim 1, wherein The illumination position on the imaging means of the illumination means can be detected from the difference signal between the image signal obtained by the imaging means when illuminated by the illumination means and the image signal obtained by the imaging means when not illuminated by the illumination means. 7. The automatic focus adjustment apparatus according to claim 6, wherein when the image signal for detecting the in-focus position cannot be obtained, illumination by the illumination unit is not performed. Means for instructing photographing preparation, and display means for displaying a subject image formed on the imaging means, and obtaining an image signal for detecting the in-focus position during display of the image on the display means An evaluation value indicating the degree of focus of the image is calculated, the position of the focus adjustment unit that maximizes the value is calculated, the distance from the position to the subject is calculated, and if the distance is greater than the predetermined distance, the preparation for shooting is completed. 2. The automatic focus adjustment apparatus according to claim 1, wherein when the image signal for detecting the in-focus position is acquired after being instructed, illumination by the illumination unit is not performed. While driving an imaging unit that photoelectrically converts a subject image formed by the photographing optical system to obtain an electrical image signal, a focus adjustment unit that adjusts the focus of the subject image formed on the imaging unit, and a focus adjustment unit while driving Focus position detection means for detecting a focus position from a part of the image signal of the image pickup means generated by the image pickup means, and illuminating all or part of the subject when acquiring the image signal for detecting the focus position In an automatic focus adjustment apparatus having illumination means, means for detecting the illumination position of the illumination means, and face detection means,
An automatic focus adjusting apparatus characterized in that, when a photometric value at a detected face position is brighter than a predetermined value, illumination by an illuminating unit is not performed when an image signal for detecting a focus position is acquired.