JP6071561B2 - Focus adjustment apparatus and method - Google Patents

Description

  The present invention relates to a focus adjustment apparatus and method, and more particularly, a focus adjustment apparatus and method for performing focus adjustment using an image signal acquired by an image sensor that photoelectrically converts a subject image formed by an imaging optical system. It is about.

  Conventionally, various AFs during continuous shooting have been proposed. For example, in Patent Document 1, the scanning range of the focusing lens may be equally distributed to both sides with the current focusing position as the center. From the viewpoint described below, the current focusing position is used as a reference. It is described that the distribution width of the scanning range may be different. In other words, since continuous shooting is performed continuously at short time intervals, the subject generally moves in the same direction between consecutive shootings. Therefore, based on the moving direction of the subject until the previous shooting, that is, based on the moving direction of the focusing lens until the previous shooting (the moving direction of the focusing position), the focusing position at the next shooting is determined to some extent. It is possible to predict.

  FIG. 13 shows an example of each in-focus position in three consecutive shootings. In the third shooting (FIG. 13C), the previous focus position is used as a reference based on the movement direction of the focus position in the previous shooting (FIG. 13A) and the previous shooting (FIG. 13B). The distribution widths (SC1, SC2) of the scanning ranges on both sides are different from each other. In the example shown in FIG. 13C, it is conceivable that the in-focus position moves in the same direction even in the next shooting, and therefore the distribution width on the same direction side as the previous movement direction is relatively large. .

  As described above, by changing the allocation range of the scanning range based on the moving direction of the in-focus position until the previous shooting, the in-focus lens can be efficiently moved, and the in-focus processing is speeded up. It becomes possible.

JP 2002-122773 A

  However, in Japanese Patent Application Laid-Open No. 2004-228620, since the reference range is not changed only by relatively increasing the distribution range of the scanning range, for example, it cannot cope with a scene in which the image plane moving speed gradually increases. When the subject is approaching at a constant speed, the image plane moving speed increases at an accelerated rate. Therefore, it is difficult to focus on a subject that moves in this manner with the technique of Patent Document 1. There is.

  In addition, since it is not determined whether the subject is stationary or moving, if the subject is mistakenly focused on the background when shooting the moving subject, it will continue to focus on the background. There is.

  The present invention has been made in view of the above problems, and when focusing on the background mistakenly, the subject continues to focus on the background without reducing the continuous shooting speed when the subject is stationary. It aims at solving.

To achieve the above object, focusing device of the present invention includes: a setting means for setting a range to move the focus lens, while moving Te set range odor by the setting means the focus lens, predetermined each divided region obtained by dividing the focus control area into a plurality of areas which are, and for the focus control area, obtains a focus evaluation value rather based on an output signal from the imaging means, the focus evaluation value for each of the divided areas peak A control means for obtaining a peak position of the focus lens at which the peak position of the focus lens and a focus evaluation value of the focus adjustment area reach a peak, and controlling the focus lens to move to the peak position of the focus adjustment area If, based on the plurality of peak positions of the focus control area determined by the control unit, the following by the control means A first prediction means for predicting the peak position of the focus control area in your, based on the plurality of peak positions of each of the divided areas obtained by the control unit, the divided region in the next control by the control means second prediction means for predicting the peak position of each peak position of the focus control area predicted by the first prediction means and the peak position of the focus control area determined by the control of the last by the control means When the difference between the two is smaller than a predetermined threshold , the peak position for each of the divided areas obtained by the previous control by the control means and the peak position for each of the divided areas predicted by the second prediction means the difference is based on the number of predetermined variation less divided regions, to the number of the difference is the predetermined change amount or more divided regions and, Utsushitai has a determining means for determining whether stationary or moving, the setting means, so as to include the peak position of the predicted the focusing regions by said first prediction means, when setting the range to move your Keru the focus lens to the next control by the control unit, the subject is judged to be moving by the determining means, the setting means, the object is stationary A range wider than the case where it is determined that the focus lens is moved in the next control is set.

  According to the present invention, when focusing on the background by mistake, it is possible to solve the problem of continuing focusing on the background without reducing the continuous shooting speed when the subject is stationary.

It is a block diagram which shows the structure of the imaging device in the 1st, 2nd, 4th embodiment of this invention. 10 is a flowchart showing imaging processing in the first to fourth embodiments. It is the schematic explaining an autofocus process. 10 is a flowchart showing continuous shooting AF processing in the first to fourth embodiments. 10 is a flowchart showing scan range setting processing in the first to fourth embodiments. 6 is a flowchart illustrating scan range expansion processing according to the first embodiment. 6 is a flowchart illustrating scan processing according to the first embodiment. Explanatory drawing of operation | movement of AF between continuous shooting with respect to the motion of a to-be-photographed object in 1st Embodiment. Explanatory drawing of operation | movement of continuous shooting AF when the to-be-photographed object in the 1st Embodiment is still. Explanatory drawing of arrangement | positioning of AF frame in the 1st-4th embodiment. The block diagram which shows the structure of the imaging device in 3rd Embodiment. Explanatory drawing regarding the setting of predetermined value ThrFP1 to compare in 4th Embodiment. Explanatory drawing of the conventional scanning range when a to-be-photographed object is moving.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is a block diagram showing the configuration of the imaging apparatus 1 according to the first embodiment of the present invention. In FIG. 1, a photographic lens barrel 31 is a light amount adjusting unit that controls the amount of light beam that has passed through an imaging optical system such as the zoom lens group 2, the focus lens group 3, and the zoom lens group 2 and the focus lens group 3. It consists of a diaphragm 4 or the like as exposure means. The subject image light that has passed through the imaging optical system and the amount of light of which has been adjusted by the diaphragm 4 is imaged on the light receiving surface of an image sensor 5 typified by a CCD or CMOS sensor. Is subjected to photoelectric conversion to output an electrical image signal.

  The imaging circuit 6 receives the image signal output from the imaging element 5 and performs various image processing to generate an image signal of a predetermined format, and the A / D conversion circuit 7 generates an analog image generated by the imaging circuit 6. The signal is converted into a digital image signal (image data). The image data output from the A / D conversion circuit 7 is temporarily stored in a memory (VRAM) 8 such as a buffer memory. The D / A conversion circuit 9 reads out an image signal stored in the VRAM 8 and converts it into an analog image signal, and also converts it into an image signal in a form suitable for reproduction display, and an image display device such as a liquid crystal display (LCD) (hereinafter referred to as “LCD”). , Referred to as “LCD”) 10 displays this analog image signal.

  The compression / decompression circuit 11 includes a compression circuit and an expansion circuit. The compression circuit reads image data temporarily stored in the VRAM 8 and converts the image data into a format suitable for storage in the storage memory 12. Apply processing. The decompression circuit performs a decoding process, a decompression process, and the like for converting the image data stored in the storage memory 12 into a form suitable for reproduction display and the like. The storage memory 12 is composed of a semiconductor memory or the like and stores image data. As the storage memory 12, a semiconductor memory such as a flash memory, or a semiconductor memory such as a card type flash memory that has a card shape or a stick shape and is detachably attached to the imaging device 1 is used. In addition, various forms such as a magnetic storage medium such as a hard disk or a floppy (registered trademark) disk are applied.

  For example, among the operation switches 24 to be described later, a mode change switch (not shown) is operated to enter the photographing mode, and when the release switch is operated to instruct an exposure recording operation, the following processing is performed. First, the image data temporarily stored in the VRAM 8 as described above is compressed and encoded by the compression circuit of the compression / decompression circuit 11 and then stored in the storage memory 12. When the playback mode is entered, the playback operation is started and the following processing is performed. First, image data stored in a compressed form in the storage memory 12 is subjected to decoding processing, expansion processing, and the like in the expansion circuit of the compression / expansion circuit 11 and then temporarily stored in the VRAM 8. The image data temporarily stored in the VRAM 8 is converted into an analog signal in a format suitable for display through the D / A conversion circuit 9 and is reproduced and displayed as an image on the LCD 10.

  The CPU 15 incorporates a calculation memory and controls the entire image pickup apparatus 1. The AE processing circuit 13 performs automatic exposure (AE) processing based on the digital image signal output from the A / D conversion circuit 7. More specifically, the AE processing circuit 13 performs arithmetic processing such as cumulative addition on the luminance value of the digital image signal for one screen digitized by the A / D conversion circuit 7 to obtain the brightness of the subject. The AE evaluation value corresponding to is calculated. This AE evaluation value is output to the CPU 15.

  The scan AF processing circuit 14 performs automatic focus adjustment (AF) processing based on the digital image signal output from the A / D conversion circuit 7. More specifically, among the digital image signals for one screen digitized by the A / D conversion circuit 7, high-frequency components of image data corresponding to a partial area of the screen designated as an AF frame are filtered with a high-pass filter ( HPF) or the like. Further, arithmetic processing such as cumulative addition is performed to calculate an AF evaluation value (focus evaluation value) corresponding to the contour component amount on the high frequency side. 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 image sensor 5 in the course of performing the AF processing. In addition, when the AF frame is one place in the central part or an arbitrary part on the screen, or in the central part or an arbitrary part on the screen and a plurality of adjacent points, the AF frame is a plurality of points distributed discretely. There are cases.

  A timing generator (TG) 16 generates a predetermined timing signal. A sensor driver 17 drives the image sensor 5. The TG 16 outputs a predetermined timing signal to the CPU 15, the imaging circuit 6, and the sensor 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 sensor driver 17 receives the timing signal of the TG 16 and drives the image sensor 5 in synchronization therewith.

  The diaphragm drive motor 21 drives the diaphragm 4, and the first motor drive circuit 18 controls the drive of the diaphragm drive motor 21. The focus drive motor 22 drives the focus lens group 3, and the second motor drive circuit 19 drives and controls the focus drive motor 22. The zoom drive motor 23 drives the zoom lens group 2, and the third motor drive circuit 20 drives and controls the zoom drive motor 23.

  The CPU 15 controls the first motor drive circuit 18, the second motor drive circuit 19, and the third motor drive circuit 20, respectively. As a result, the diaphragm 4, the focus lens group 3, and the zoom lens group 2 are driven and controlled via the diaphragm drive motor 21, the focus drive motor 22, and the zoom drive motor 23, respectively. Specifically, the CPU 15 controls the first motor drive circuit 18 based on the AE evaluation value calculated by the AE processing circuit 13 to drive the aperture drive motor 21 so that the aperture amount of the aperture 4 becomes appropriate. AE control to be adjusted is performed.

  Further, the CPU 15 controls the second motor drive circuit 19 based on the AF evaluation value 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 controls the third motor drive circuit 20 and controls the zoom drive motor 23 to control the zoom lens group 2. The zooming operation is performed for the imaging optical system.

  The operation switch 24 includes various switch groups, and includes the following, for example. A main power switch for activating the imaging device 1 to supply power, a release switch for starting a shooting operation (storage operation), a playback switch for starting a playback operation, a change in zoom magnification, that is, the zoom lens group 2 For example, a zoom switch for instructing movement. In the present embodiment, the release switch is configured by a two-stage switch of a first stroke (hereinafter referred to as “SW1”) and a second stroke (hereinafter referred to as “SW2”). SW1 generates an instruction signal for starting AE processing and AF processing prior to the imaging operation. SW2 generates an instruction signal for starting an exposure recording operation for actually capturing and recording an image.

  An EEPROM 25 is an electrically rewritable read-only memory in which programs for performing various controls, data used for performing various operations, and the like are stored in advance. 26 is a battery, 28 is a flash light emitting unit, 27 is a switching circuit that controls the flash light emission of the flash light emitting unit 28, 29 is a display element such as an LED that displays a warning, etc. 30 is a voice guidance or warning It is a speaker.

  The AF auxiliary light emitting unit 33 includes a light source such as an LED that illuminates all or a part of the subject when acquiring the AF evaluation value, and the AF auxiliary light driving circuit 32 drives the AF auxiliary light emitting unit 33.

  The shake detection sensor 35 detects camera shake and the like, and the shake detection circuit 34 processes the signal of the shake detection sensor 35. The face detection circuit 36 receives the output from the A / D conversion circuit 7 and detects the face position and the face size on the screen. In the face detection circuit 36, a part characterizing the face such as eyes and eyebrows is searched on the image from the digital image signal output from the A / D conversion circuit 7, and the position of the person's face on the image is obtained. Further, the size and inclination of the face are obtained from the positional relationship such as the interval between the parts characterizing the face.

  Next, the shooting operation of the imaging apparatus 1 in the first embodiment will be described using the flowchart shown in FIG.

  In the description of the present invention, the operation of acquiring the AF evaluation value based on the output of the image sensor 5 while moving the focus lens group 3 to a predetermined position is referred to as scanning. In addition, the position of the focus lens that acquires the AF evaluation value is the scan point, the interval between the scan points is the scan interval, the number of the AF evaluation value is acquired as the number of scan points, and the movement range of the focus lens group 3 that acquires the AF evaluation value is It shall be called a scan range. Further, an area for acquiring an image signal for detecting a focus position is referred to as an AF frame.

  The imaging process shown in FIG. 2 is executed when the main power switch of the imaging apparatus 1 is in the on state and the operation mode of the imaging apparatus 1 is in the shooting (recording) mode.

  First, in S1, as described above, the CPU 15 converts the subject optical image formed on the image pickup device 5 through the photographing lens barrel 31 into the image pickup circuit 6, the A / D conversion circuit 7, the VRAM 8, and the D / A conversion. An image is displayed on the LCD 10 via the circuit 9. By performing this process every predetermined time, the user can observe the live view image on the LCD 10. The user can confirm the scene to be photographed by observing the image displayed on the LCD 10.

  Next, in S2, the state of the release switch of the operation switch 24 is confirmed. When the release switch is operated by the photographer and the CPU 15 confirms that the SW1 is turned on, the process proceeds to the next S3, and AE processing is performed. Here, the CPU 15 controls the first motor drive circuit 18 based on the AE evaluation value obtained by the AE processing circuit 13, thereby controlling the opening state of the diaphragm 4 via the diaphragm drive motor 21. Specifically, if the AE evaluation value is low (the obtained image is dark), the aperture 4 is opened, and if the AE evaluation value is high (the obtained image is bright), the aperture 4 is controlled to be appropriately controlled. An image having brightness (AE evaluation value) is obtained.

  Subsequently, AF processing is performed in S4. In the AF process, the position of the focus lens group 3 where the high-frequency component of the image signal obtained by the image pickup device 5 is the largest is obtained, and the CPU 15 controls the focus drive motor 22 via the second motor drive circuit 19 to obtain the focus lens. Move group 3 to the determined position. Here, an outline of the AF processing will be described with reference to FIG.

  The AF process 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 image sensor 5 is the largest. First, the CPU 15 controls the focus drive motor 22 via the second motor drive circuit 19 to move the focus lens group 3 to a position corresponding to infinity (“A” in FIG. 3). Then, a scan range from the infinity position to a position (“B” in FIG. 3) corresponding to the closest distance set in each photographing mode is scanned at a preset scan interval. Then, an AF evaluation value is acquired by the scan AF processing circuit 14 at each scan point. When the movement of the focus lens group 3 is completed, the position where the high frequency component is maximized, that is, the peak position ("C" in FIG. 3) is obtained from the acquired AF evaluation value, and the focus lens group 3 is moved to that position. To do. Here, when the peak position cannot be obtained because the reliability of the AF evaluation value is low, the focus lens group 3 is moved to a predetermined position called a fixed point.

  Note that in order to increase the speed of the scan AF process, the scan interval of S4 is set at predetermined stoppable positions instead of all stop positions at which the focus lens group 3 can be stopped. In this case, as shown in FIG. 3, the AF evaluation value is not acquired at the point where the AF evaluation value actually becomes the maximum value, and the AF evaluation values may be acquired at the points a1, a2, and a3 before and after that. obtain. In such a case, the peak position C is obtained by calculation from the point where the maximum value is obtained and the points before and after the obtained AF evaluation value.

Here, when the position of the focus lens group 3 is X1, the AF evaluation value becomes maximum and the value is Y1 (a2 in FIG. 3), and the AF evaluation values acquired at the front and rear positions X2 and X3 are Y2 and Y3. (A1, a3 in FIG. 3), the position X0 of the focus lens group 3 at the peak position C is
X0 = {(Y3-Y2) ・ X1 + (Y3-Y1) ・ X2 + (Y2-Y1) ・ X3} / {2 ・ (Y3-Y1)}
Is required. However, Y1> Y3 and Y1 ≧ Y2. In this way, the interpolation calculation is performed to obtain the point (C in FIG. 3) where the AF evaluation value is maximized.

  Before obtaining the peak position, the reliability of the AF evaluation value is evaluated in S4. If the reliability is sufficient, the point at which the AF evaluation value becomes the maximum value is obtained, and “AF OK” is displayed in S6. This is performed by turning on the display element 29, and at the same time, processing such as displaying a green frame on the LCD 10 is performed. If the reliability of the AF evaluation value is low as a result of the evaluation, the process for obtaining the point at which the AF evaluation value is maximum is not performed, and “AF NG” is displayed in S6. This is performed by blinking the display element 29 or the like, and at the same time, processing such as displaying a yellow frame on the LCD 10 is performed. Needless to say, the display method and display method described above are examples, and the present invention is not limited to these methods.

  As a method for determining the reliability of the AF evaluation value in S4, for example, the method described in Japanese Patent No. 04235422 can be used.

  After completing the AF process in this way, the CPU 15 checks in S6 whether the ON state of SW1 continues. If it is off, the process returns to S1, and if it is on, the process proceeds to S7 to confirm SW2. If SW2 is off, the process returns to S6 and waits until SW2 is turned on. However, if SW1 is turned off during this time, the process returns to S1.

  If SW2 is on, the process proceeds to S8. In S8, the value of the continuous shooting counter for counting the number of continuous shots is initialized to 1. In S9, the actual exposure process (main shooting) is executed, and the value of the continuous shooting counter is incremented by one. When the exposure process ends, the process proceeds to S10, and the SW2 is confirmed again. If SW2 is off, the process returns to S6, waits for SW1 to be turned off, and ends the process.

  On the other hand, if the ON state of SW2 is maintained, the process proceeds to S11, and processing related to AF (inter-continuous shooting AF processing) performed between shooting is performed. Then, after the continuous shooting AF process is completed, the process returns to S9 and the actual exposure process is executed.

  As a matter of course, the continuous shooting AF processing is performed only when continuous shooting is instructed by the photographer. If continuous shooting is not instructed (such as when the single shooting mode is specified by the photographer), after the exposure process in S9 is completed, the state of SW2 is checked in S10, and the ON state of SW2 is maintained. If it remains, it waits until SW2 is turned off. That is, in S9 to S11, only the SW2 state check in S10 is performed without performing the exposure process in S9 and the counting up of the continuous shooting counter, and the continuous shooting AF process in S11.

  Next, the continuous shooting AF performed in S11 will be described in detail with reference to FIG. Note that, as described above, when continuous shooting is not instructed, the continuous shooting AF process is not performed, and thus the operation when continuous shooting is instructed will be described. Further, since this process is executed only for the second and subsequent frames of continuous shooting, when this process is executed for the first time, it becomes the second continuous shooting process, and the value of the continuous shooting counter at this time is 2. .

  In S21, it is checked whether or not it is the second continuous shooting. If it is the second continuous shooting (the value of the continuous shooting counter is 2), the process proceeds to S22, and if it is not the second, the process proceeds to S23.

  In S22, the position of the focus lens group 3 (peak position FP1) at the time of the first continuous shooting is set as the center ObjP2 of the scan range. Further, although the scan range is set, priority is given to not extending the shooting interval during continuous shooting. Specifically, the AF operation is completed between the shootings in consideration of the processing performed during the continuous shooting, for example, the readout time of the image signal from the image sensor 5 and the check time for the next shooting operation. Determine the number of scan points. Further, a scan interval capable of AF operation (focus position search) is set. That is, the scan range is the product of (the number of scan points−1) and the scan interval. However, when the set scan range exceeds the entire region (range from the closest end to be focused to the infinity end), the entire region is set as the scan range. In addition, if the end of the set scan range exceeds the near end or infinity end where focusing is possible, the scan range is shifted so that the scan range does not exceed the near end or infinity end where focusing is possible. To.

  Note that the peak position FP1, the center ObjP2 of the scan range, and the like used here are all obtained from AF evaluation values obtained from the output signal of the entire frame in the scan of S31 described later.

  If the setting of the scan range is completed in S22, the process proceeds to S31.

On the other hand, if it is not the second shooting, it is checked in S23 whether the third shooting is continuous shooting (the value of the continuous shooting counter is 3). If it is the third sheet, the process proceeds to S24, and if it is not the third sheet, the process proceeds to S25. In the case of the third image, there is information on the two peak positions (peak positions FP1, FP2) of the first image and the second image of continuous shooting as the focus position history information. Therefore, in S24, assuming that the time between continuous shootings is constant, subject position prediction (prediction of peak position at the time of third shooting) is performed by primary approximation from information on two peak positions, and the scan range is determined. The center position ObjP3 is obtained from equation (1).
ObjP3 = FP2 + (FP2-FP1) × FpAdj3 (1)
The parameter FpAdj3 is a parameter for setting the weighting of the prediction result of the subject position and the previous peak position, and takes a value of 0 to 1. A scan range is set based on the center position ObjP3 calculated in this way, and the subject image is shifted from the previous scan range in the moving direction. Here, as in S22, the scan range is set with priority given to not extending the shooting interval in continuous shooting. If the setting of the scan range is completed in S24, the process proceeds to S31.

In S25, since the fourth and subsequent shots are taken, the focus position history information includes information on the peak positions for at least three shots. As described above, since the time between continuous shootings is constant, the subject position is predicted (prediction of the peak position at the time of the current shooting) by secondary approximation. For example, the center position ObjP4 of the scan range at the time of photographing the fourth image is obtained from Expression (2).
ObjP4
= (FP1-3FP2 + 3FP3) × FpAdj4 + FP3 (1-FpAdj4)
= (FP1-3FP2 + 2FP3) × FpAdj4 + FP3 (2)
Here, unlike the third sheet, the scan range is not set in S25.

  Next, in S26, an absolute value of a difference between the peak position FP3 of the third image capturing and the center position ObjP4 at the time of the fourth image capturing is obtained, and this is set as a movement amount of the subject in the optical axis direction. For the fifth and subsequent images, the absolute value of the difference between the obtained center position and the peak position in the previous shooting is the amount of movement.

  In S27, the amount of movement of the subject in the optical axis direction obtained in S26 is compared with a predetermined value to determine whether or not the subject has moved greatly in the optical axis direction. As a result, if the amount of movement of the subject in the optical axis direction is larger than the predetermined value, the process proceeds to S28, and the scan range is set. The setting method in this case is the same as the setting method performed in S22 and S24, and is set with priority given not to extending the shooting interval in continuous shooting. Thereafter, the process proceeds to S31.

  On the other hand, if the amount of movement of the subject in the optical axis direction is equal to or smaller than the predetermined value, the process proceeds to S29, where it is determined whether the subject is stationary or moving, and the scan range is set. In order to solve the problem that the moving main subject goes out of the scanning range and does not focus, the processing is performed so that the moving main subject must be set to be included in the scanning range. Because. However, in the case of a stationary subject, such a scan range setting has an adverse effect of increasing unnecessary operation time.

  The phenomenon that the moving subject is outside the scanning range occurs as follows. For example, when the ratio of the background subject in the AF frame is large in the first shooting, the background may be focused, and the background may continue to be focused thereafter. This is because the proportion of the background subject in the AF frame is large, so the background is focused on the first shot, and after that the proportion of the background subject in the AF frame is large, so it is focused on the background, not the main subject. To do. When the main subject moves and the ratio in the AF frame becomes larger than the background, the moved main subject is outside the scanning range set in S24 and the like, and is not in focus.

  Therefore, this predetermined value used for comparison in S27 is used to determine whether or not the result of continuous shooting AF is stuck to the background. The value is a value by which it can be determined that the subject is not moving in consideration of the detection error of the peak position and the predicted position.

  Here, the scan range setting process performed in S29 will be described with reference to FIG. An example of the AF frame arrangement is shown in FIG. In the example shown in FIG. 10, the AF frame 901 (focus adjustment area) used for the continuous shooting AF is divided into three in both the horizontal direction and the vertical direction, and nine divided AF frames 902 (00 to 22 frames) are created. Since the AF evaluation value is acquired from each divided AF frame 902 (divided region), nine AF evaluation values can be obtained at one scan point. Then, the nine AF evaluation values are added for each scan point to obtain an AF evaluation value for the entire AF frame 901. Then, the reliability of the AF evaluation value in the divided AF frame 902 is checked for each of the nine AF frames, and as a result, the movement amount of each frame in the AF frame determined to be reliable is checked, so that the subject to be imaged can be determined. It is determined whether the object is moving or stationary.

  In S41, initialization processing is performed. In addition to resetting the counter to be used, the divided AF frame 902 to be determined is initialized. When the AF frame is divided into nine as shown in FIG. 10, first, “00 frame” is processed.

  In S42, the reliability of the AF evaluation value in the scan at the time of the previous photographing of the evaluated AF frame is evaluated. For example, a method described in Japanese Patent No. 04235422 can be used. If it is determined that there is no reliability (or is lower than a predetermined reliability threshold), it is determined in S47 that there is reliability (or more than a predetermined reliability threshold). If YES, go to S43. In S43, the movement amount ΔFPmn of the subject in the divided AF frame 902 being processed is obtained. The method for obtaining this is the same as the processing in S25 and S26 of FIG. 4, but the details will be described below.

Since the process in FIG. 5 is a process in the fourth and subsequent photographing, at least three scans are performed first. Therefore, there is at least three pieces of information regarding the peak position in the divided AF frame 902 being processed. Therefore, if the time between continuous shootings is constant, the subject position in the divided AF frame 902 being processed can be predicted by secondary approximation. For example, the predicted position ObjP4mn of the subject at the time of photographing the fourth image is obtained from Expression (3) ObjP4mn = FP1mn−3 · FP2mn + 3 · FP3mn (3)
However, FP1mn is a peak position in the divided AF frame 902 being processed, which is obtained by scanning at the time of photographing the first image, FP2mn is the second image, and FP3mn is the third image.

  Then, the absolute value of the difference between the peak position FP3mn in the divided AF frame 902 being processed obtained by scanning at the time of shooting the third image and the center position ObjP4mn of the scan range at the time of shooting the fourth image is obtained. Further, this is set as a movement amount ΔFPmn of the subject in the optical axis direction in the divided AF frame 902 being processed.

  Next, in S44, the obtained movement amount ΔFPmn is compared with a predetermined value (change amount), and if it is greater than or equal to the predetermined value (change amount or more), the process proceeds to S45 and the moving subject counter is counted up. On the contrary, if it is less than the predetermined value, the process proceeds to S46, and the stationary subject counter is counted up.

  The predetermined value used here is smaller than the predetermined value used in S27 of FIG. When the entire frame is a moving subject pulled on the background, the scan range for the second and subsequent frames is determined by the peak position (focus position) of the AF evaluation value of the entire frame, so the divided AF frame has a sufficient scan range. There is a possibility that the second and third sheets will not stop climbing. This is because the calculated movement amount of the subject may be smaller than the actual movement amount. For example, when the predetermined value of S27 is 5 times the open depth, it is set to 2.5 times the half open depth.

  Next, in S47, it is checked whether the process has been completed for all the divided AF frames 902. If not completed, the process proceeds to S52 to update the divided AF frame 902 to be processed. For example, the processing target divided AF frame is 01 frame when the 00 frame processing is completed, 02 frame when the 01 frame processing is completed, 10 frame when the 02 frame processing is completed, and so on. 902 is updated.

  If the processing of S42 to S45 or S46 is performed for all the divided AF frames 902, the process proceeds from S47 to S48, and the values of the moving subject counter and the stationary subject counter are checked. If the moving subject counter ≦ Nm (the second threshold value or less) and the stationary subject counter ≧ Ns (the first threshold value or more), the process proceeds to S49. Otherwise, the process proceeds to S50. Here, Nm · Ns is a threshold value for determining whether the shooting target is a moving subject or a stationary subject. In the case of being influenced by the background, there is a possibility that the subject is a moving subject even if the subject movement amount ΔFP based on the peak position obtained from the AF evaluation value obtained in the entire AF frame 901 is small. This is because the background is in the AF frame 901. Therefore, in the case of a moving subject, there should be an AF frame in the divided AF frame 902 in which the subject movement amount ΔFP is large without being influenced by the background. It is.

  Therefore, if the value of the moving subject counter is larger than the threshold value Nm, the moving subject is photographed, and the peak position of the entire AF frame 901 may stick to the background, so the process proceeds to S50. Further, when the value of the stationary subject counter is smaller than the threshold value Ns, even if the value of the moving subject counter is small, the subject may be affected by shake of the subject or movement of the subject during the scan and out of the AF frame because of the moving subject. There is sex. Therefore, even when the value of the stationary subject counter is smaller than the threshold value Ns, the moving subject is photographed, and the peak position of the entire AF frame 901 may stick to the background. Therefore, only when the value of the moving subject counter is equal to or smaller than the threshold value Nm and the value of the stationary subject counter is equal to or larger than the threshold value Ns, it is determined that the still subject is being photographed, and the process proceeds to S49. Note that when the AF frame is divided into 3 × 3 9 frames, for example, Nm is set to 2 and Ns is set to a value of about 7 as an example. Of course, the present invention is not limited by these values.

  In S49, a scan range for a stationary subject is set. The setting method in this case is the same as the setting method performed in S22, S24, and S28, and is set with priority not to extend the shooting interval in continuous shooting. For example, in the case of the fourth shooting, the scan range is set with priority given not to extend the shooting interval in the continuous shooting centering around the predicted position ObjP4 of the subject at the time of the fourth shooting obtained in S25. Is done.

  On the other hand, in S50, the scan range for the moving subject is set. Here, background sticking occurs, and it is determined that the moving subject cannot be tracked. Therefore, focusing performance is more important than continuous shooting speed. Accordingly, in order to ensure focusing on the subject, a scan range of about 1 to 3 times the scan range set in S49 and the like is set in consideration of the focal length, the shooting distance, the assumed moving speed of the subject, and the like. .

  FIG. 6 shows the procedure of the scan range expansion process performed in S50. First, in S61, an initial scan range is set. Here, similarly to S49, the number of scan points is determined so that the AF operation is completed during photographing, and further, the scan interval at which the AF operation (focus position search) is possible is set. The scan range is the product of (the number of scan points minus 1) and the scan interval. When the scan range set in this way exceeds the entire region (range from the closest end to be focused to the infinity end), or when the entire range can be covered by shifting the scan range (YES in S62). The entire area is set as a scan range (S63).

  If the entire setting cannot be covered with the above setting, the number of scan points is increased by 1 without changing the scan interval in S64. The scan range obtained by the product of (the number of scan points minus 1) and the scan interval exceeds the entire range (range from the closest end to be focused to the infinity end), or the entire range can be covered by shifting the scan range. In this case (YES in S65), the entire area is set as the scan range (S63).

  If the whole area is not covered even if the number of scan points is increased by 1, the scan interval is not changed in S66, but the number of scan points before the increase of 1 (the number of initial scan points) is doubled. The scan range obtained by the product of (the number of scan points minus 1) and the scan interval exceeds the entire range (range from the closest end to be focused to the infinity end), or the entire range is covered by shifting the scan range. If possible (YES in S67), the entire area is set as the scan range (S63).

  If the entire area is not covered, it is determined whether or not the scan range set in S68 is more than half of the entire area. If it is more than half of the entire area, the scan range set at that time (initial The double of the scan range) is set as the scan range as it is. If the scan range set in S68 is less than half of the entire area, half of the entire scan range is set as the scan range (S69).

  When the processing of S50 is completed as described above, the continuous shooting counter is initialized to 1 in S52. As a result, when it is determined that the subject has not moved due to continuing to focus on the background even though it is a moving subject, shooting at that time is not the first continuous shooting, but the first shot Treated as a shoot. Therefore, the next shooting is also handled as the second shooting. The same applies to the following photographing. If the above processing is completed, the process proceeds to S31.

  In S31, scanning is performed according to the flowchart of FIG. First, an AF evaluation value of each divided AF frame 902 is acquired, and then an AF evaluation value of the AF frame 901 is calculated. Here, the AF evaluation value in the divided AF frame 902 in the focus lens group 3 is added for each scan point, and this is used as the AF evaluation value in the AF frame 901 at each scan point in the focus lens group 3. Thereafter, the peak position of the AF evaluation value of the divided AF frame 902 and the peak position of the AF evaluation value of the AF frame 901 are obtained. If it is divided into nine as shown in FIG. 10, the peak positions of a total of ten AF evaluation values are obtained.

  In step S32, the focus lens group 3 is moved to the peak position of the AF frame 901. In the second and subsequent images of continuous shooting, when the AF evaluation value is not reliable and the peak position cannot be obtained, the focus lens group 3 is moved to the previous peak position, and the first image is displayed. The focus lens group 3 is not moved to a fixed point. This is because it is considered that the subject exists at a position where the distance from the imaging device does not change much during continuous shooting. That is, it is considered that it is more likely that an in-focus image is obtained when the focus lens group 3 is moved to the previous peak position (focus lens movement position) than when the focus lens group 3 is moved to a fixed point.

Similarly, for the fifth and subsequent shots (continuous shooting counter value is 5 or more), subject position prediction (prediction of peak position at the time of current shooting) is performed by secondary approximation, and the scan range is determined. Center position ObjP (n) is obtained from equation (4). A scan range is set based on the center position ObjP (n) calculated in this way, and the subject image is shifted from the previous scan range in the moving direction.
ObjP (n)
= (FP (n-1) -3FP (n-2) + 2FP (n)) * FpAdj (n)
+ FP (n-1) (4)

  However, if the amount of movement of the subject is equal to or less than the predetermined value as in the case of the fourth image, the process proceeds to S29, where it is determined whether or not the subject is a stationary subject and the scan range is set based on the result according to the operation procedure of FIG. .

  Such processing may lead to a reduction in the continuous shooting speed (number of shots per unit time), but when the background sticking occurs and the moving subject cannot be tracked, the main subject is surely focused. be able to. If the subject is not actually moving, or if the subject is moving, it will not reduce the continuous shooting speed (number of images taken per unit time).

  The above operation will be described with reference to FIG. FIG. 8A shows an example in which the focus follows the main subject, and FIG. 8B shows an example in which the focus does not follow the main subject at the beginning of continuous shooting because the background is once focused.

  First, the scene in FIG. 8A will be described as an example. The parameters FpAdj3 · FpAdj4... FpAdj (n) shown in the equation (1) and the like are parameters for setting the weighting of the prediction result of the subject position and the immediately preceding peak position, and take values of 0 to 1. However, in FIG. 8, all are set to “1”.

  When SW1 is turned on and a series of photographing operations is started, the peak position FP1 of the first photographing is obtained by the scan AF in S4 of FIG.

  In the second continuous shooting AF process performed in S11 in FIG. 2, the first peak position FP1 is set as the predicted movement position Objp2 of the subject in the second shooting. Then, the scan range is set by determining the number of scan points so that the AF operation is completed between photographing and setting the scan interval at which the AF operation (focus position search) is possible. The scan range is the product of (the number of scan points minus 1) and the scan interval. If the scan range set in this way exceeds the entire range (the range from the closest end to be focused to the infinity end), or if the entire range can be covered by shifting the scan range, the entire range is set as the scan range. To do. AF is performed in the scan range set in this way (the range of the arrow shown in FIG. 8). As a result, the peak position FP2 is obtained.

  In the continuous shooting AF process for the third image, the predicted movement position ObjP3 of the subject in the third image is calculated from the peak position FP1 of the first image and the peak position FP2 of the second image using Equation (1). Ask. Then, the scan range is set in the same manner as the second image capturing, and AF is performed in the set scan range (the range indicated by the arrow in FIG. 8). As a result, the peak position FP3 is obtained.

  In the continuous shooting AF for the fourth frame, the expected movement of the subject in the shooting of the fourth frame is obtained from the first, second, and third peak positions FP1, FP2, and FP3 using equation (2). The position ObjP4 is obtained. Then, the movement amount in the optical axis direction of the subject (absolute value of the difference between the peak position FP3 of the third image capturing and the center position ObjP4 of the scan range at the time of the fourth image capturing) is obtained.

  As shown in FIG. 8A, when this value is equal to or greater than a predetermined value, a scan range is set around the expected movement position ObjP4 of the subject (the range of the arrow shown in FIG. 8), and AF is performed in that range. As a result, the peak position FP4 is obtained.

  In the subsequent shooting, the peak position is obtained in the same manner. That is, in the n-th shooting, the predicted movement position ObjP of the subject in the n-th shooting is calculated using the equation (4) from the peak positions of the n-3, n-2, and n−1. (N) is obtained. Then, the absolute value of the difference between the movement amount of the subject in the optical axis direction (the peak position FP (n−1) of the (n−1) -th shooting and the center position ObjP (n) of the scan range at the time of the n-th shooting. ) If this value is greater than or equal to a predetermined value, a scan range is set around the expected movement position ObjPn of the subject (the range of the arrow shown in FIG. 8), and AF is performed within that range to obtain the peak position FPn. If it is less than the predetermined value, it is determined whether the subject is a stationary subject or a moving subject. If the subject is determined to be a stationary subject, a scan range is set around the expected movement position ObjPn of the subject (not shown). Then, AF scanning is performed in that range, and the peak position FPn is obtained. If it is determined that the subject is a moving subject, the scan range is expanded (not shown), and AF is performed in that range to obtain the peak position FPn. The peak position is obtained in the same manner in subsequent imaging.

  On the other hand, as shown in FIGS. 8B and 9, when the amount of movement of the subject in the optical axis direction is not equal to or greater than a predetermined value, determination as to whether the subject is a stationary subject or a moving subject and setting of the scan range is performed. This process is performed when the subject is stationary and the scan range is set to a relatively narrow range as before, and when the moved main subject falls outside the scan range. This is in order to solve the harmful effect of not burning. Therefore, it is necessary to set a relatively wide range so that the moved main subject is included in the scan range.

  As shown in FIG. 8B, when the subject is stuck to the background regardless of the moving subject, the peak position of the AF evaluation value is in the divided AF frame 902 as shown by □ in the figure. There is something that follows a moving subject without sticking to the background because the background does not enter the frame. If there is such a tracking frame, it can be determined that the subject is moving and the entire frame is stuck to the background due to the influence of the background. Note that x is a position where the AF evaluation value of the AF frame 901 reaches a peak. In the figure, □ and x are shifted for the sake of clarity, but they may actually overlap.

  If the subject is attached to the background in this way, the amount of movement of the subject is greater than or equal to a predetermined value, taking into consideration the focal length, shooting distance, and assumed subject movement speed, so that the subject can be focused securely. The scan range is set to be about 1 to 3 times the scan range. Then, AF is performed within the set scan range. As a result, the peak position FP4 is obtained as shown in FIG. This shooting is treated as the first continuous shooting.

  As shown in FIG. 8B, once the background has been focused, this is detected in the fourth shot, and accurate focusing is performed by performing scan AF over a relatively wide range. The position can be obtained.

  In the continuous shooting AF for the fifth frame in the case of FIG. 8B, the peak position FP4 of the fourth frame is set as the predicted movement position Objp5 of the subject in the shooting of the fifth frame. Then, a scan range is set in the same manner as in the second imaging, and AF is performed in the set scan range (the range indicated by the arrow shown in FIG. 8B), and the peak position FP5 is obtained.

  In the sixth continuous shooting AF, the predicted moving position ObjP6 of the subject in the sixth shooting is obtained from the fourth peak position FP4 and the fifth peak position FP5 by using Equation (1). Then, the scan range is set in the same manner as the second image capturing, and AF is performed in the set scan range (the range indicated by the arrow shown in FIG. 8B). As a result, the peak position FP6 is obtained.

  In the continuous shooting AF for the seventh frame, the expected moving position ObjP7 of the subject in the seventh shooting is obtained from the peak positions of the fourth, fifth, and sixth frames using Equation (2). Then, the movement amount of the subject in the optical axis direction (absolute value of the difference between the peak position FP6 of the sixth image capturing and the center position ObjP7 of the scan range at the time of the seventh image capturing) is obtained.

  If this value is greater than or equal to a predetermined value, a scan range is set around the expected movement position ObjP7 of the subject (the range of the arrow shown in FIG. 8), and AF is performed within that range, and the peak position FP7 is obtained. If it is less than the predetermined value, it is determined whether the subject is a stationary subject or a moving subject. If the subject is determined to be a stationary subject, a scan range is set around the expected movement position ObjPn of the subject (not shown). Then, AF is performed in the range, and the peak position FPn is obtained. If it is determined that the subject is a moving subject, the scan range is expanded (not shown), and AF is performed in that range to obtain the peak position FPn. The peak position is obtained in the same manner in subsequent imaging.

  In the case of a stationary subject as shown in FIG. 9, the AF evaluation value of the AF frame divided as shown by □ in the figure is the same as the peak position of the AF evaluation value of the entire frame and hardly changes. If the peak position of the AF evaluation value of such a divided AF frame has hardly changed, it can be determined that the subject is stationary.

  In this case, a scan range is set around the predicted movement position ObjP4 of the subject (the range of the arrow shown in FIG. 9), and AF is performed in that range. As a result, the peak position FP4 is obtained. In the subsequent shooting, the peak position is obtained in the same manner. That is, in the n-th shooting, the predicted movement position ObjP of the subject in the n-th shooting is calculated using the equation (4) from the peak positions of the n-3, n-2, and n−1. (N) is obtained. Then, the absolute value of the difference between the movement amount of the subject in the optical axis direction (the peak position FP (n−1) of the (n−1) -th shooting and the center position ObjP (n) of the scan range at the time of the n-th shooting. ) If this value is equal to or greater than a predetermined value, a scan range is set around the expected movement position ObjP (n) of the subject (the range indicated by the arrow in FIG. 9), and AF is performed within that range to obtain the peak position FPn. . If it is less than the predetermined value, it is determined whether the subject is a stationary subject or a moving subject. If the subject is determined to be a stationary subject, a scan range is set around the expected movement position ObjPn of the subject (not shown). Then, AF is performed in the range, and the peak position FPn is obtained. If it is determined that the subject is a moving subject, the scan range is expanded (not shown), and AF is performed in that range to obtain the peak position FPn. The peak position is obtained in the same manner in subsequent imaging.

  Next, the scanning operation performed in S31 of FIG. 4 will be described with reference to the flowchart of FIG.

  First, in S71, the focus lens group 3 is moved to a scan start position at a speed faster than the speed during the scanning operation. In this embodiment, the scan start position is set at one end of the set scan range. In S72, the AF evaluation value of the area corresponding to the AF frame (901 and 902 in FIG. 10) set in the imaging area and the position of the focus lens group 3 are stored in a calculation memory (not shown) built in the CPU 15. In S73, it is checked whether or not the lens position is at the scan end position. If it is the end position, the process proceeds to S75, and if not, the process proceeds to S74. The scan end position is set at the other end of the set scan range. In S74, the focus lens group 3 is moved and moved in a predetermined direction by a predetermined amount to the next scan point. In S75, the peak position of the focus lens group 3 corresponding to the position where the AF evaluation value is maximized is calculated from the AF evaluation value at each scan point stored in S72 and the position of the focus lens group 3.

  As described above, according to the first embodiment, it is possible to prevent the adverse effect of focusing on the background without focusing on the moved main subject, and on the stationary subject without failing to reduce the continuous shooting speed. It becomes possible to focus on.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. The method of obtaining the AF evaluation value of the entire AF frame 901 from the AF evaluation value of the divided AF frame 902 obtained from the scan result in S31 of FIG. 4 is different from the first embodiment described above. As described above, since the AF evaluation value is acquired from each divided AF frame 902, nine AF evaluation values can be obtained at one scan point. In the first embodiment, nine AF evaluation values are added for each scan point to obtain an AF evaluation value for the entire AF frame 901.

  On the other hand, in the second embodiment, the maximum value is extracted in the horizontal direction and added in the vertical direction among the AF evaluation values of the respective scan points of each divided AF frame 902. The camera orientation is also taken into consideration in the horizontal and vertical directions.

  For example, in the case where the camera is divided into nine divided AF frames as shown in FIG. 10, if the camera is in the horizontal position, among the AF evaluation values of the 00 frame, the 01 frame, and the 02 frame, the maximum AF for each scan point. Select an evaluation value and record it in memory. Next, among the AF evaluation values of the 10th frame, the 11th frame, and the 12th frame, the maximum AF evaluation value is selected for each scan point, and added to the previously recorded memory value and recorded. Further, among the AF evaluation values of the 20th frame, the 21st frame, and the 22nd frame, the maximum AF evaluation value is selected for each scan point, added to the memory value, and recorded.

  When the camera is in the vertical position, the AF evaluation value for each scan point is selected from the AF evaluation values of 00 frame, 10 frames, and 20 frames and recorded in the memory. Next, among the AF evaluation values of the 00 frame, the 11th frame, and the 21st frame, the maximum AF evaluation value is selected for each scan point, and added to the previously recorded memory value and recorded. Further, among the AF evaluation values of the 00 frame, the 12th frame, and the 22nd frame, the maximum AF evaluation value is selected for each scan point, and is added to the memory value and recorded.

  Other processes are the same as those in the first embodiment.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. The difference from the first embodiment described above is that a plurality of scan AF processing circuits are provided, and the AF evaluation values of the entire AF frame 901 and divided AF frame 902 are obtained from the respective AF scan processing circuits.

  FIG. 11 is a block diagram illustrating a configuration of the imaging apparatus 1 according to the third embodiment. The imaging apparatus 1 shown in FIG. 11 has a first scan AF processing circuit 141 (first processing means) and a second scan AF processing circuit 142 (second processing means) in addition to the configuration shown in FIG. It is a thing. The function of the first scan AF processing circuit 141 and the second scan AF processing circuit 142 is to calculate the AF evaluation value in the designated AF frame as described in the first embodiment. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  The operation of the image pickup apparatus 1 in the third embodiment is the same as that in the first embodiment, but has a plurality of scan AF processing circuits and includes the entire AF frame 901 and divided AF frame 902 shown in FIG. At the same time, the AF evaluation value that is the output is used in the processing. The first scan AF processing circuit 141 sets an AF frame so as to acquire the AF evaluation value of the entire AF frame 901 indicated by a dotted line in FIG. 10, and the second scan AF processing circuit 142 has nine divisions indicated by a solid line in FIG. The AF frame is set so that the AF evaluation value is acquired from the AF frame 902.

  The operation is performed according to FIG. 4 as in the first embodiment, and in the scan of S31, the peak value of the AF evaluation value of the entire frame is acquired from the AF evaluation value obtained from the first scan AF processing circuit 141. Further, the peak value of the AF evaluation value of each frame divided from the AF evaluation value obtained from the second scan AF processing circuit 142 is acquired. In other processes, the same operation as in the first embodiment is performed according to FIG.

  Further, in the process of S43 in FIG. 5, the peak value of the AF evaluation value of each of the divided AF frames 902 is obtained using the AF evaluation value obtained from the second scan AF processing circuit 142. Next, the predicted position of the subject at the time of the next shooting is obtained using the peak position of the AF evaluation value in each shooting during continuous shooting. Then, by obtaining the difference between them, the movement amount ΔFPmn of the subject is obtained. Other processes in FIG. 8 are the same as those in the first embodiment.

<Fourth Embodiment>
Next, a fourth embodiment of the present invention will be described. The difference from the first embodiment is in the following points. That is, the predetermined value used in S27 of FIG. 4, the predetermined value used in S44 of FIG. 5, brightness, the result of white balance processing (WB), the distance, the focal length, and the shooting mode are changed. It is. Note that the predetermined value used in S27 of FIG. 4 is a threshold value for determining whether or not the subject has moved greatly in the optical axis direction, and the predetermined value used in S44 of FIG. 5 is the value in the divided AF frame. This is a threshold value for determining whether or not the subject is moving in the optical axis direction.

  Note that the configuration of the imaging apparatus 1 in the fourth embodiment is the same as that in the first embodiment. In the fourth embodiment, the operation is performed according to FIG. 4 as in the first embodiment. In S27, the movement amount ΔFP of the subject obtained in S26 is compared with a predetermined value ThrFP1. Here, the predetermined value is not a constant value, and the possibility that the subject to be photographed is a moving subject is estimated from the brightness, WB result, distance, focal length, and photographing mode, and a predetermined value ThrFP1 to be compared in accordance with the estimated value ThrFP1 I will change.

The predetermined reference value is ThrFPBase, which is about half that of the first embodiment. Then, ThrFP1 is increased by Equation (5) according to the situation up to 2.5 times this ThrFPBase.
ThrFP1
= ThrFPBase
× (1 + ValTv + ValAv + ValISO + ValMode) (5)

Here, ValTv takes a value of 0 to 1 according to the shutter speed (Tv value) set by the photographer in the shutter priority mode. For example, as shown in FIG. 12A, it is assumed that 0 changes when the Tv value = 1/250 seconds or less, 1 changes when the Tv value = 1/1000 seconds or more, and the interval changes linearly.
Further, ValAv takes a value of 0 to 1 according to the aperture value (Av value) set by the photographer in the aperture priority mode. For example, as shown in FIG. 12 (b), if the Av value = F2.0 or less (open side from F2.0), 1; if the Av value = F4.0 or more (small aperture side), 0; And However, since the photographer may consider the brightness of the subject regarding the setting of the aperture value, the aperture value of the reference point is offset by the brightness in consideration of this. For example, if Lv12 is used as a reference and it becomes 1 step brighter than that, the aperture value of the reference point is offset by 0.5 step. If Lv13, 1 if Av value = F2.4 or less, 0 if Av value = F4.7 or more, 0 if Lv14, 1 if Av value = F2.8 or less, 0 if Av value = F5.6 or more. Therefore, either ValTv or ValAv is always zero.

  ValISO takes a value from 0 to 1 in accordance with the setting when the photographer consciously sets the ISO sensitivity. For example, as shown in FIG. 12, the ISO sensitivity is 0 or less, and the ISO sensitivity is 3200 or more. If it is 1, it will change linearly in the meantime.

  Further, when the shooting mode is set to a mode for shooting a fast moving subject such as a sports mode, 0.4 × ThrFPBase is added to ThrFP1. If the WB result is sunlight, 0.1 × ThrFPBase, and if the ISO sensitivity setting is HighAuto (automatically set the ISO sensitivity but is set to a relatively high ISO sensitivity), 0.1 × ThrFPBase. Are respectively added. However, if the macro mode for photographing a close subject is set, ThrFP1 = ThrFPBase, regardless of the above result.

  Other than the above, the same operation as in the first embodiment is performed according to FIGS. 4 and 5, and the process proceeds from S29 to S44. Then, as the predetermined value ThrFP2 for comparison used in S44, the comparison is performed as a half value of the aforementioned ThrFP1. Thereafter, the same operation as in the first embodiment is performed.

  According to the first to fourth embodiments, when the possibility of a moving subject is high, the frequency of determining that the background sticking occurs and cannot follow the moving subject is increased. The frequency can be lowered. This solves the problem of continuing to focus on the background when the background is mistakenly focused, and can easily realize an increase in the continuous shooting speed in the case of a stationary subject.

  Although the first to fourth embodiments have been described by taking a compact type digital camera as an example, the present invention can also be applied to AF during a live view of a digital video camera or a digital single lens reflex camera.

  The object of the present invention can also be achieved by executing the following processing. That is, a storage medium that records a program code of software that realizes the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU, MPU, etc.) of the system or apparatus is stored in the storage medium. This is the process of reading the code.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

  Moreover, the following can be used as a storage medium for supplying the program code. For example, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM or the like. Alternatively, the program code may be downloaded via a network.

  Further, the present invention includes a case where the function of the above-described embodiment is realized by executing the program code read by the computer. In addition, an OS (operating system) running on the computer performs part or all of the actual processing based on an instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Is also included.

  Furthermore, a case where the functions of the above-described embodiment are realized by the following processing is also included in the present invention. That is, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

Claims (11)

Setting means for setting a range for moving the focus lens;
While moving Te set range odor by the setting means the focus lens, each divided region obtained by dividing the focus control area to a predetermined plurality of regions, and, for the focus control area, the output from the image pickup means It obtains a focus evaluation value rather based on the signal, obtains the peak position of the focus lens where the focus evaluation value and the peak position of the focus lens where the focus evaluation value for each of the divided regions has a peak the focus control area has a peak Control means for controlling the focus lens to move to the peak position of the focus adjustment region ;
Based on the plurality of peak positions of the focus control area determined by said control means, and first prediction means for predicting the peak position of the focus control area in the next control by said control means,
Second prediction means for predicting peak positions for each of the divided areas in the next control by the control means based on a plurality of peak positions for each of the divided areas obtained by the control means;
When the difference between the peak position of the focus adjustment area obtained by the previous control by the control means and the peak position of the focus adjustment area predicted by the first prediction means is smaller than a predetermined threshold, A divided region in which the difference between the peak position for each divided region obtained by the previous control by the control unit and the peak position for each divided region predicted by the second predicting unit is smaller than a predetermined change amount. And a judging means for judging whether the subject is moving or stationary based on the number and the number of divided areas whose difference is equal to or more than the predetermined change amount ,
The setting means, so as to include the peak position of the predicted the focusing regions by said first prediction means, to set the range for moving the focus lens Keru us to the next control by said control means,
When the determination unit determines that the subject is moving, the setting unit moves the focus lens in the next control over a wider range than when the subject is determined to be stationary. A focus adjustment device characterized by being set as follows. Before SL determining means, a peak position of each of the divided areas obtained by the control of the last by said control means, determined the difference between the peak position of the divided every region predicted by the second predicting means the pre the number of variation is less than the divided area which is the first threshold or more and the number of the difference is the predetermined change amount or more of the divided regions, small have second than the first threshold value The focus adjustment apparatus according to claim 1, wherein it is determined that the subject is stationary when the threshold is equal to or less than the threshold value, and the subject is determined to be moving otherwise.   The determination means determines in advance the difference between the peak position for each of the divided areas obtained by the previous control by the control means and the peak position for each of the divided areas predicted by the second prediction means. The focus adjustment apparatus according to claim 1, wherein the subject is determined to be moving when the number of divided areas smaller than the change amount is smaller than a first threshold.   The determination means determines in advance the difference between the peak position for each of the divided areas obtained by the previous control by the control means and the peak position for each of the divided areas predicted by the second prediction means. 2. The focus adjustment apparatus according to claim 1, wherein the subject is determined to be moving when the number of divided areas equal to or greater than the change amount is greater than a second threshold value. The control means obtains a peak position of the focus adjustment area based on a value obtained by adding the focus evaluation values of the plurality of divided areas based on the output signal obtained at the same timing. Item 5. The focus adjustment apparatus according to any one of Items 1 to 4 . The control means divides the focus adjustment region in a horizontal direction and a vertical direction, respectively, and is obtained at the same timing for each of the plurality of divided regions arranged in one of the horizontal direction and the vertical direction. 6. The maximum value of the focus evaluation value based on the output signal is obtained, and the peak position of the focus adjustment region is obtained based on a value obtained by adding the obtained maximum values . The focus adjusting apparatus according to item 1 . The control means according to claim 1, characterized in that a second processing means for obtaining a first processing means for determining the focus evaluation value for each of the divided areas, the focus evaluation value of the focus control area The focus adjustment apparatus according to any one of 1 to 6 . The predetermined threshold value used by the determination unit is determined according to at least one of the brightness of the subject, the result of white balance processing, the distance to the subject, the focal length, and the shooting mode. Item 8. The focus adjustment device according to any one of Items 1 to 7 . A setting step in which the setting means sets a range for moving the focus lens;
Control means, wherein while the focus lens is moving shift Te range odor set in the setting step, for each divided area obtained by dividing the focus control area to a predetermined plurality of regions, and, for the focus control area, imaging It obtains a focus evaluation value rather based on an output signal from the means, of the focus lens where the focus evaluation value and the peak position of the focus lens where the focus evaluation value for each of the divided regions has a peak the focus control area has a peak A focus adjustment step of obtaining a peak position and repeating control for moving the focus lens to the peak position of the focus adjustment region ;
The first predicting means predicts the peak position of the focus adjustment area in the next control by the focus adjustment process based on the plurality of peak positions of the focus adjustment area obtained in the focus adjustment process . The prediction process;
A second predictor for predicting a peak position for each of the divided regions in the next control in the focus adjustment step based on the plurality of peak positions for each of the divided regions obtained in the focus adjustment step; The prediction process;
A determination unit determines a difference between a peak position of the focus adjustment region obtained by the previous control by the focus adjustment step and a peak position of the focus adjustment region predicted by the first prediction step. If smaller , the difference between the peak position for each of the divided areas determined by the previous control by the focus adjustment step and the peak position for each of the divided areas predicted by the second prediction step is determined in advance. A determination step of determining whether the subject is moving or stationary based on the number of divided areas smaller than the amount of change and the number of divided areas where the difference is equal to or greater than the predetermined amount of change. And
In the setting step, a range for moving the focus lens in the next control by the focus adjustment step is set so as to include the peak position of the focus adjustment region predicted in the first prediction step,
When it is determined that the subject is moving in the determination step, the setting step is a range in which the focus lens is moved in the next control over a wider range than when the subject is determined to be stationary. Focus adjustment method characterized by setting as follows. A program for causing a computer to execute a control method in the focus adjustment apparatus,
The control method is:
A setting step in which the setting means sets a range for moving the focus lens;
Control means, each of the divided region of the focus lens obtained by dividing the focus control area to a predetermined while dynamic shift Te range odor set by the setting step into a plurality of regions, and, for the focus control area, the imaging means It obtains a focus evaluation value rather based on an output signal from the peak of the focus lens where the focus evaluation value and the peak position of the focus lens point evaluation value for each of the divided regions has a peak the focus control area has a peak A focus adjustment step for determining a position and repeating control for moving the focus lens to a peak position of the focus adjustment region ;
The first predicting means predicts the peak position of the focus adjustment area in the next control by the focus adjustment process based on the plurality of peak positions of the focus adjustment area obtained in the focus adjustment process . The prediction process;
A second predictor for predicting a peak position for each of the divided regions in the next control in the focus adjustment step based on the plurality of peak positions for each of the divided regions obtained in the focus adjustment step; The prediction process;
A determination unit determines a difference between a peak position of the focus adjustment region obtained by the previous control by the focus adjustment step and a peak position of the focus adjustment region predicted by the first prediction step. If smaller , the difference between the peak position for each of the divided areas determined by the previous control by the focus adjustment step and the peak position for each of the divided areas predicted by the second prediction step is determined in advance. A determination step of determining whether the subject is moving or stationary based on the number of divided areas smaller than the amount of change and the number of divided areas where the difference is equal to or greater than the predetermined amount of change. And
In the setting step, a range for moving the focus lens in the next control by the focus adjustment step is set so as to include the peak position of the focus adjustment region predicted in the first prediction step,
When it is determined that the subject is moving in the determination step, the setting step is a range in which the focus lens is moved in the next control over a wider range than when the subject is determined to be stationary. A program characterized by causing a control method to be set to be executed. A computer-readable storage medium storing the program according to claim 10 .

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