JP5904781B2 - Automatic focus adjustment device, control method thereof, and program - Google Patents

Description

The present invention relates to an automatic focus adjustment device, a control method therefor, and a program, and more particularly, to a technology related to autofocus used for an electronic still camera, a video, and the like.

2. Description of the Related Art Conventionally, in an electronic still camera or the like, as a method of moving a focus lens position to focus on a subject, an autofocus (AF) method that automatically performs a focusing operation using an image signal obtained from an image sensor such as a CCD Is used. In this AF method, there is a technique for increasing the speed by determining the subject peak position from the graph shape of the focus evaluation value and changing the focus speed at a position away from the subject peak position during the AF scan operation.
For example, a ratio between the change amount of the focus evaluation value and the change amount of the lens position within a predetermined time is calculated as an evaluation value change rate, and the lens position is changed depending on whether the evaluation value change rate is in an increasing state or a decreasing state. Some change the speed of change (see Patent Document 1).
In addition, the peak position is predicted from three points where the focus evaluation value is increasing, and the variation of the prediction result is driven within a predetermined range. When the increase becomes near 0 before that, the focus is stopped, and the predicted peak position is far away. In some cases, it is moved at a high speed, and then re-predicted at a low speed (see Patent Document 2).

Japanese Patent Laid-Open No. 7-7650 JP-A-8-29667

When an AF scan method that acquires a focus evaluation value while driving the focus lens is applied, there is a time lag between the determination of being near the subject peak position and the speed control.
Further, when the camera settings such as the contrast, frequency, aperture, and exposure of the subject are different, the graph shape of the focus evaluation value is different. As a result, when determining the subject peak position based on the graph shape of the focus evaluation value, depending on the subject, it is not enough to decelerate to a predetermined speed that is a sampling interval that can secure AF accuracy near the subject peak position. There is a problem that it ends up.
In Patent Document 1 and Patent Document 2, the time lag from the determination of the graph shape of the focus evaluation value to the speed control is not considered. Also, the method of determining the peak shape of the focus evaluation value is not changed according to the setting of the subject or camera. For this reason, depending on the setting of the subject and the camera, the speed control may not be in time for the subject peak position, resulting in poor focus accuracy.

  The present invention has been made in view of the above points, and an object of the present invention is to enable AF to be performed with high accuracy and high speed regardless of the setting of the subject and the camera.

An automatic focusing apparatus according to the present invention includes an imaging unit that photoelectrically converts light that has passed through an imaging optical system including a focus lens to generate an imaging signal, and a generation unit that generates a focus signal indicating the contrast of a subject from the imaging signal. And a control means for controlling the position of the focus lens based on the focus signal, the control means during the first scan operation for driving the focus lens in one direction. The focus signal is sequentially acquired, and the drive speed of the focus lens is changed according to the gradient of the focus signal with respect to the position of the focus lens. After detecting the first focus lens position at which the focus signal acquired in one scan operation reaches a peak, the focus lens Perform a second scan operation of driving in one direction, to control the position of the focus lens based on the second focus lens position where the said focal signal obtained in the second scanning operation reaches a peak, the first One condition is that the difference between the first focus lens position and the position of the focus lens corresponding to the focus signal before and after the first focus lens position exceeds a predetermined value .

  According to the present invention, the peak position of the focus evaluation value is calculated by changing the driving speed of the focus lens, and the peak position of the focus evaluation value is calculated while driving the focus lens again under a certain condition. Therefore, AF can be performed with high accuracy and high speed regardless of the subject and camera settings.

It is a block diagram which shows the structure of the imaging device which concerns on embodiment. It is a flowchart explaining operation | movement of the imaging device which concerns on embodiment. It is a flowchart explaining AF operation | movement in FIG. 4 is a flowchart for explaining initial focus driving in FIG. 3. It is a flowchart explaining the peak detection check in FIG. It is a flowchart explaining the setting of the focus speed in FIG. FIG. 6 is a flowchart illustrating focus detection value gradient detection in FIGS. 3 and 5. FIG. 6 is a flowchart illustrating calculation of a focus evaluation value gradient threshold value SlopeThr in FIGS. 3, 4, and 5.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a block diagram showing a configuration of an imaging apparatus (electronic camera) according to an embodiment to which the present invention is applied. Reference numeral 101 denotes a photographing lens including a zoom mechanism. Reference numeral 102 denotes an aperture and a shutter that control the amount of light. Reference numeral 103 denotes an AE processing unit that performs AE (automatic exposure) processing. Reference numeral 104 denotes a focus lens for focusing on an image sensor 107 described later. A motor 105 drives the focus lens 104. An AF processing unit 106 performs AF (automatic focusing) processing.

  Reference numeral 107 denotes an image sensor as light receiving means or photoelectric conversion means for converting reflected light from the subject into an electrical signal. Reference numeral 108 denotes an A / D converter, which includes a CDS circuit that removes output noise from the image sensor 107 and a non-linear amplifier circuit that is performed before A / D conversion. Reference numeral 109 denotes an image processing unit. Reference numeral 110 denotes a format conversion unit. Reference numeral 111 denotes a high-speed built-in memory (for example, a random access memory or the like (hereinafter referred to as DRAM)), which is used as a high-speed buffer as temporary image storage means or a working memory or the like in image compression / decompression. An image recording unit 112 includes a recording medium such as a memory card and its interface.

  Reference numeral 113 denotes a system control unit (hereinafter referred to as CPU), which controls the system such as a shooting sequence. Reference numeral 114 denotes an image display memory (hereinafter referred to as VRAM). Reference numeral 115 denotes an image display unit. In addition to image display, in addition to display for operation assistance and camera status display, a shooting screen and a distance measurement area are displayed during shooting.

  Reference numeral 116 denotes an operation unit for operating the camera from the outside. The operation unit 116 includes the following, for example. These include a menu switch for performing various settings such as a shooting function of the imaging apparatus and settings for image playback, a zoom lever for instructing a zoom operation of the shooting lens, and an operation mode switching switch between the shooting mode and the playback mode. Reference numeral 117 denotes a shooting mode switch for selecting a shooting mode such as a macro mode, a distant view mode, or a sports mode. The shooting mode switch 117 changes the distance measurement distance range, the AF operation, and the like according to the shooting mode selected by the user. Reference numeral 118 denotes a main switch for turning on the system. Reference numeral 119 denotes a switch (hereinafter referred to as SW1) for performing a shooting standby operation such as AF or AE. Reference numeral 120 denotes a photographing switch (hereinafter referred to as SW2) that performs photographing after the operation of SW1 (119).

  Reference numeral 121 denotes an angular velocity sensor for detecting camera movement caused by camera shake or panning. Reference numeral 122 denotes a moving object detection unit that detects a moving object from luminance information in the screen.

  In the present embodiment, the imaging apparatus having the above-described configuration obtains a focus evaluation value based on a video output signal obtained via the imaging optical system including the focus lens 104 and the imaging element 107, and the position of the focus lens 104. It functions as an automatic focusing device that adjusts.

Hereinafter, the operation of the imaging apparatus according to the present embodiment will be described with reference to FIGS. Each process described below is realized under the control of the system control unit 113.
FIG. 2 is a flowchart for explaining the operation of the imaging apparatus according to the present embodiment.
In step S201, the AE processing unit 103 performs AE processing from the output of the image processing unit 109, and proceeds to step S202. In step S202, the state of SW1 (119) is checked. If ON, the process proceeds to step S203, and if not, the process proceeds to step S201. In step S203, an AF operation described later (see FIG. 3) is performed, and the process proceeds to step S204. Here, the exposure conditions (shutter speed, aperture, sensitivity) during the AF operation are determined by the AE process in the immediately preceding step S201. In step S204, the state of SW1 (119) is checked. If ON, the process proceeds to step S205, and if not, the process proceeds to step S201. In step S205, the state of SW2 (120) is checked. If ON, the process proceeds to step S206, and if not, the process proceeds to step S204. After performing a photographing operation in step S206, the process proceeds to step S201.

  FIG. 3 is a flowchart for explaining the AF operation in step S203 of FIG. In step S301, a distance measurement area is set as a predetermined area in the screen, and the process proceeds to step S302. In step S302, a scan range corresponding to the shooting mode and focal length is set, and the process proceeds to step S303. In step S303, an initial focus drive (see FIG. 4) described later is performed, and the process proceeds to step S304. In this initial focus driving, driving to the start position of the AF scan is performed.

  In step S304, after setting a focus speed (drive speed of the focus lens 104) described later (see FIG. 6), the process proceeds to step S305. In step S305, focus driving is started in a predetermined direction at the focus speed set in step S304, and the process proceeds to step S306. Here, the predetermined direction is set to a direction opposite to the initial focus drive in step S303.

  In step S306, the focus evaluation value in the distance measurement area set in step S301 is acquired, and the process proceeds to step S307. In step S307, the current position of the focus lens 104 is acquired, and the process proceeds to step S308. In step S308, a gradient evaluation value gradient detection (see FIG. 7) described later is performed, and the flow proceeds to step S309. In step S309, a focus evaluation value gradient threshold SlopeThr (described later) is calculated (see FIG. 8), and the process proceeds to step S310.

  In step S310, whether or not the gradient of the focus evaluation value detected in step S308 is greater than or equal to the gradient threshold SlopeThr calculated in step S309, and whether or not the focus speed set in step S304 or step S311 described later is set to a high speed. Check out. As a result, if so, the process proceeds to step S311; otherwise, the process proceeds to step S313. In step S311, the focus speed is changed to a low speed, and the process proceeds to step S312. In step S312, focus drive is performed at the focus speed changed in step S311 and the process proceeds to step S313. Thus, when focus driving is started at high speed when AF scanning starts, deceleration control of the focus lens 104 can be performed when the vicinity of the focus position can be determined.

  In step S313, it is checked whether or not the current position of the focus lens 104 acquired in step S307 is within the scan range set in step S302. As a result, if it is within the scan range, the process proceeds to step S306; otherwise, the process proceeds to step S314. Here, a series of operations in steps S306 to S313 are performed for a time corresponding to one frame at the current frame rate. Further, the focus evaluation value acquired in step S306 and the lens position acquired in step S307 are associated with each other and used for calculation of the peak position of the focus evaluation value in step S315 described later. At this time, since the focus lens 104 is driven during the acquisition of the focus evaluation value, the focus lens position at the center timing of the exposure time is calculated and associated with the focus evaluation value.

  In step S314, the driving of the focus lens 104 is stopped, and the process proceeds to step S315. In step S315, using the focus evaluation value acquired in step S306 and the position of the focus lens 104 corresponding to the focus evaluation value (obtained in step S307), the peak position of the focus evaluation value is calculated, and the process proceeds to step S316. In step S316, an in-focus determination is made, and the process proceeds to step S317. The processing so far is an example of the first control means, the first control procedure, and the first control processing in the present invention.

  In step S317, a condition for performing the scan again (hereinafter referred to as rescan) is determined. Here, it is determined whether or not a difference between the peak position of the focus evaluation value calculated in step S315 and the focus position from which the focus evaluation values before and after the focus evaluation value have exceeded a predetermined value (first condition). As a result, if it exceeds, the rescan is performed and the process proceeds to step S318. If not, the process proceeds to step S326. The predetermined value is a value that can maintain accuracy with respect to the calculation of the in-focus position.

  However, even if the first condition is satisfied, if the second condition is satisfied, the process proceeds to step S326 without performing rescanning. For example, if it is out of focus in step S316, rescanning is not performed. Also, if the aperture is reduced by a predetermined amount or more, if the image size is smaller than the predetermined size, or if the compression rate of the image is larger than a predetermined value, the rescan is not performed if the depth becomes deeper than the predetermined value at the time of shooting. . In addition, when a shooting mode with priority on shooting speed is selected, or when a time lag until shooting is desired to be reduced as much as possible, such as when the shutter button is pressed at once, rescanning is not performed. In addition, when the subject moves more than a predetermined amount or the like, the rescan is not performed when the focusing accuracy is reduced when the rescan is performed.

  In step S318, a distance measurement range centered on the peak position of the focus evaluation value calculated in step S315 is set. The distance measurement range set here is set narrower if the gradient of the focus evaluation value or the change rate of the gradient is large, and is set wider if the gradient of the focus evaluation value or the change rate of the gradient is small. In addition, when the aperture is reduced by a predetermined amount or more, or when it is difficult to calculate the peak of the focus evaluation value due to a deep depth, the range of distance measurement is set to be widened. In step S319, the focus lens 104 is moved to the scan start position. In step S320, the focus evaluation value within the distance measurement range set in step S318 is acquired, and the process proceeds to step S321. In step S321, the current position of the focus lens 104 is acquired, and the process proceeds to step S322. In this case, the focus speed is fixed at the low speed set in step S311.

  In step S322, it is checked whether or not the current position of the focus lens 104 acquired in step S321 is within the distance measuring range set in step S318. As a result, if it is within the distance measurement range, the process proceeds to step S320, and if not, the process proceeds to step S323. In step S323, the driving of the focus lens 104 is stopped, and the process proceeds to step S324. In step S324, using the focus evaluation value acquired in step S320 and the corresponding position of the focus lens 104 (obtained in step S321), the peak position of the focus evaluation value is calculated, and the process proceeds to step S325. In step S325, an in-focus determination is made, and the process proceeds to step S326. The processing so far is an example of the second control means, the second control procedure, and the second control processing in the present invention.

  If re-scanning is performed in step S322, the focus lens 104 is driven to the peak position of the focus evaluation value obtained in step S324, and if re-scanning is not performed, the focus lens 104 is driven to the peak position of the focus evaluation value obtained in step S315. Then, the AF operation ends.

  FIG. 4 is a flowchart for explaining the initial focus drive in step S303 of FIG. In step S401, the focus speed is decreased and the process proceeds to step S402. Here, the low speed in the initial focus drive is set at a minimum speed at which, for example, a gradient of a focus evaluation value described later can be determined. In step S402, focus drive is started in a predetermined direction at the focus speed set in step S401, and the process proceeds to step S403. Here, the predetermined direction is set to, for example, a direction in which the existence probability of the subject is considered high, a direction toward either the far end or the near end with respect to the current focus lens position.

  In step S403, the focus evaluation value in the distance measurement area set in step S301 is acquired, and the process proceeds to step S404. In step S404, the current position of the focus lens 104 is acquired, and the process proceeds to step S405. In step S405, a peak detection check (see FIG. 5) described later is performed, and the process proceeds to step S406. In step S406, it is checked whether or not the peak detection result checked in step S405 is OK. If so, the process proceeds to step S409, and if not, the process proceeds to step S407. In step S407, it is checked whether or not the peak detection result checked in step S405 is a decrease, and the number of times of decrease is larger than the decrease frequency threshold value. In step S408, it is checked whether or not the current position of the focus lens 104 has reached the end in the traveling direction. If so, the process proceeds to step S409, and if not, the process proceeds to step S403.

  In step S409, the gradient threshold value SlopeThr of the focus evaluation value described later is calculated (see FIG. 8), and the process proceeds to step S410. In step S410, it is checked whether or not the gradient of the focus evaluation value detected in the gradient detection of the focus evaluation value in step S503, which will be described later, is greater than or equal to SlopeThr calculated in step S409. As a result, if so, the process proceeds to step S411, otherwise proceeds to step S412. In step S411, FASTAF determination is NG, and the process proceeds to step S413. Here, FASTAF determination is an index for determining whether to start focus driving at high speed by determining whether or not the current position of the focus lens 104 is in the vicinity of the focus position in step S305 which is the AF scan operation start timing. Become one. The FASTAF determination is used for setting the focus speed in the next step S304. In step S412, the FASTAF determination is OK, and the flow advances to step S413. In step S413, the focus lens 104 is stopped and the process proceeds to step S304.

  FIG. 5 is a flowchart for explaining the peak detection check in step S405 of FIG. In step S501, the maximum and minimum values of the focus evaluation values acquired in step S403 so far are obtained and stored, and the process proceeds to step S502. After calculating a focus evaluation value gradient threshold SlopeThr (see FIG. 7), which will be described later, in step S502, the process proceeds to step S503. In step S503, after focus detection value gradient detection (see FIG. 8) described later is performed, the process proceeds to step S504.

  In step S504, it is checked whether or not the focus evaluation value acquired this time has increased by a predetermined amount or more with respect to the focus evaluation value acquired last time. If so, the process proceeds to step S505. If not, the process proceeds to step S514. . In step S505, the number of reductions is cleared to 0, and the process proceeds to step S506. In step S506, the number of increases is incremented, and the process proceeds to step S507. In step S507, it is checked whether or not the increase count is greater than the acceleration / deceleration determination threshold value. If so, the process proceeds to step S508, and if not, the process proceeds to step S511. In step S508, it is checked whether or not the gradient of the focus evaluation value is greater than or equal to SlopeThr calculated in step S502. If so, the process proceeds to step S509, and if not, the process proceeds to step S510. In step S509, the focus speed is changed to a low speed, and the process proceeds to step S512. In step S510, the focus speed is changed to a high speed, and the process proceeds to step S512. In step S511, FASTAF determination is OK, and the process proceeds to step S513. In step S512, the FASTAF determination is set to NG, and the process proceeds to step S513. In step S513, the peak detection result is increased, and the process proceeds to step S525.

  In step S514, it is checked whether or not the current focus evaluation value has decreased by a predetermined amount with respect to the previous focus evaluation value. If so, the process proceeds to step S515, and if not, the process proceeds to step S521. In step S515, the number of increases is 1 or more, and the current focus evaluation value is decreased by a predetermined percentage or more than the maximum focus evaluation value stored in step S501, and the maximum value stored in step S501. And whether the difference between the minimum value and the minimum value is a predetermined amount or more and the peak position is not the end of the focus evaluation value data acquired so far. As a result, if all the conditions are satisfied, the process proceeds to step S520, and if not, the process proceeds to step S516. In step S516, the increase count is cleared to 0, and the process proceeds to step S517. In step S517, the decrease count is incremented, and the process proceeds to step S518. In step S518, the FASTAF determination is OK, and the flow advances to step S519. In step S519, the peak detection result is decreased, and the process proceeds to step S525. In step S520, the peak detection result is OK, and the process proceeds to step S525.

  In step S521, it is determined whether or not the number of times the focus evaluation value has not changed is greater than the acceleration / deceleration determination threshold value. If so, the process proceeds to step S522, and if not, the process proceeds to step S523. In step S522, the focus speed is changed to high speed, and the flow advances to step S523. In step S523, FASTAF determination is OK, and the flow advances to step S524. In step S524, the peak detection result is regarded as no change, and the process proceeds to step S525.

In step S525, the focus lens 104 is driven at the focus speed, and the process proceeds to step S406.
Thereby, it is possible to determine whether or not the focus position is in the vicinity based on the graph shape of the focus evaluation value until the focus lens 104 is driven to the AF scan start position. Further, even during the focus drive, when the focus lens is away from the focus position, the focus lens is driven at a high speed, and in the vicinity of the focus position, the focus drive time can be shortened by driving at a low speed. .

  FIG. 6 is a flowchart for explaining setting of the focus speed in step S304 of FIG. In step S601, it is checked whether the FASTAF determination is OK. If so, the process proceeds to step S602, and if not, the process proceeds to step S608. In step S602, it is checked whether or not the amount of camera motion detected by the acceleration sensor unit 121 is equal to or smaller than a predetermined amount. If so, the process proceeds to step S603, and if not, the process proceeds to step S608. Thereby, in the focus evaluation value gradient detection in steps S308 and S503, it is possible to reduce the influence of erroneous detection due to the fluctuation of the focus evaluation value due to camera shake. In step S603, it is checked whether or not the variation in the angle of view detected by the moving object detection unit 122 is smaller than a predetermined amount. If so, the process proceeds to step S604, and if not, the process proceeds to step S608. In step S604, it is checked whether or not the luminance is within a predetermined range. If so, the process proceeds to step S605, and if not, the process proceeds to step S608. In step S605, it is checked whether or not the focal length is longer than the predetermined distance in the current camera setting. If so, the process proceeds to step S606, and if not, the process proceeds to step S608. In step S606, it is checked whether or not the distance measurement distance range is longer than the predetermined distance in the current camera setting. If so, the process proceeds to step S607, and if not, the process proceeds to step S608. In step S607, the focus speed is changed to a high speed, and the process proceeds to step S305. In step S608, the focus speed is changed to a low speed, and the process proceeds to step S305.

  FIG. 7 is a flowchart illustrating focus detection value gradient detection in step S308 of FIG. 3 and step S503 of FIG. In step S701, the current lens position acquired in step S307 or step S404 is set as Pos1, and the process proceeds to step S702. In step S702, the current focus evaluation value acquired in step S306 or step S403 is set as T1, and the process proceeds to step S703. In step S703, the previous lens position acquired in step S307 or step S404 is set to Pos2, and the process proceeds to step S704. In step S704, the previous focus evaluation value acquired in step S306 or step S403 is set as T2, and the process proceeds to step S705. In step S705, using (T1-T2) / (Pos1-Pos2) as the gradient of the focus evaluation value, the process proceeds to step S309 or step S504.

  FIG. 8 is a flowchart illustrating the calculation of the focus evaluation value gradient threshold value SlopeThr in step S309 in FIG. 3, step S409 in FIG. 4, and step S502 in FIG. In step S801, the current aperture and the state of the shutter 102 are checked to acquire the current aperture value, and the process proceeds to step S802. In step S802, the size of the ranging area set in step S301 is acquired, and the process proceeds to step S803. In step S803, the contrast value in the distance measurement area set in step S301 is acquired, and the process proceeds to step S804. Here, the contrast value in the distance measurement area is a difference between the maximum value and the minimum value of the luminance values in the distance measurement area set in step S301. Thereby, even if the subject is not in focus, the contrast of the subject in the distance measurement area can be grasped to some extent. In step S804, the frequency in the ranging area set in step S301 is acquired, and the process proceeds to step S805. Here, the method of acquiring the frequency within the distance measurement area is not the main point of the present invention, and thus detailed description thereof is omitted. In step S805, the current lens speed is acquired, and the process proceeds to step S806.

  In step S806, SlopeThr0 serving as a reference for calculating the gradient threshold value SlopeThr is determined in the next step S807, and the process proceeds to step S807. Here, SlopeThr0 is determined in the setting of the reference subject and camera. Further, the method of determining SlopeThr0 may be changed depending on the application. For example, in the initial focus drive in step S303 in FIG. 3, it is only necessary to decelerate at a position exceeding the subject peak so that the subject peak can be detected during the AF scan operation performed later. On the other hand, during the AF scan operation, the focus lens speed must be decelerated to ensure the AF accuracy before exceeding the subject peak position. Therefore, SlopeThr0 is changed in step S409 or S502 during initial focus driving before AF scan and in step S309 during AF scan operation.

In step S807, the gradient threshold value SlopeThr of the focus evaluation value is calculated, and the process proceeds to steps S310, S410, and S503. Here, the gradient threshold value SlopeThr is calculated by the following calculation formula, for example.
SlopeThr = SlopeThr0 × MMP × WinSize × Freq / Speed / FNum
FNum: Coefficient determined by the aperture value
MMP: Coefficient determined by the contrast in the distance measurement area
Freq: Coefficient determined by the frequency within the distance measurement area
WinSize: Coefficient determined by ranging area size
Speed: a coefficient determined by the focus lens speed Thereby, even when the graph shape of the focus evaluation value differs depending on the subject or camera setting, the subject peak position can be appropriately determined.

  In this embodiment, the focus lens speed is adjusted at a low speed or a high speed by determining whether or not the gradient of the focus evaluation value is larger than a predetermined threshold value. The speed may be finely varied.

  Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. A part of the above-described embodiments may be appropriately combined.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program. It is a process to be executed.

DESCRIPTION OF SYMBOLS 101: Shooting lens 102: Aperture and shutter 103: AE processing unit 104: Focus lens 105: Motor 106: AF processing unit 107: Image sensor 108: A / D conversion unit 109: Image processing unit 110: Format conversion unit 111: DRAM 112: Image recording unit 113: System control unit 114: VRAM 115: Image display unit 116: Operation unit 117: Shooting mode switch 118: Main switch 119: Shooting standby switch 120: Shooting switch 121: Angular velocity sensor unit 122: Moving object detection unit

Claims (16)

Imaging means for photoelectrically converting light that has passed through a photographing optical system including a focus lens to generate an imaging signal;
Generating means for generating a focus signal indicating the contrast of a subject from the imaging signal;
An automatic focus adjustment device having control means for controlling the position of the focus lens based on the focus signal,
The control means sequentially acquires the focus signal during a first scan operation for driving the focus lens in one direction, and drives the focus lens according to a gradient of the focus signal with respect to the position of the focus lens. Change
The control means detects the first focus lens position at which the focus signal acquired in the first scanning operation reaches a peak when the first condition is satisfied, and then moves the focus lens in one direction. A second scan operation is performed, and the position of the focus lens is controlled based on the second focus lens position at which the focus signal acquired in the second scan operation peaks .
The first condition is when the difference between the position of the first focus lens and the position of the focus lens corresponding to the focus signal before and after the first focus lens position exceeds a predetermined value. . Said control means, said to include a first focus lens position, auto-focusing device according to claim 1, characterized in that to set the range for driving the focus lens in the second scanning operation. The control unit changes a range in which the focus lens is driven in the second scanning operation according to a gradient of the focus signal with respect to the position of the focus lens when the first focus lens position is detected. The automatic focusing apparatus according to claim 2 , wherein: The control means, automatic focusing device according to claim 2 or 3 ranges for driving the focus lens in the second scanning operation, and changes depending on the aperture value. Wherein, in the second scanning operation, an automatic focusing device according to any one of claims 1 to 4, characterized in that to drive the focus lens at a fixed speed. If it meets the second condition, said control means, even if satisfying the first condition, any one of claims 1 to 5, characterized in that does not perform the second scanning operation 2. The automatic focusing apparatus according to item 1. The automatic focus adjustment apparatus according to claim 6 , wherein when the second condition is satisfied, the control unit controls the position of the focus lens based on the position of the first focus lens. The automatic focus adjustment apparatus according to claim 6 or 7 , wherein the second condition is a case where a result of detection of the first focus lens position is out of focus. The automatic focus adjustment apparatus according to any one of claims 6 to 8 , wherein the second condition is a case where the diaphragm is stopped by a predetermined amount or more. Wherein the second condition, the automatic focusing device according to any one of claims 6 to 9 image size is equal to or is smaller than a predetermined size. Wherein the second condition, the automatic focusing device according to any one of claims 6 to 10 compression ratio of the image is characterized in that when more than a predetermined value larger. The automatic focus adjustment apparatus according to any one of claims 6 to 11 , wherein the second condition is a case where a photographing mode with priority on photographing speed is selected. The automatic focus adjustment apparatus according to any one of claims 6 to 12 , wherein the second condition is a case where the subject has moved a predetermined amount or more. Wherein the second condition, the automatic focusing device according to any one of claims 6 to 13, characterized in that when you press one stroke of the shutter button. A method for controlling an automatic focus adjustment apparatus including an imaging unit that photoelectrically converts light that has passed through a photographing optical system including a focus lens to generate an imaging signal,
Generating a focus signal indicating the contrast of the subject from the imaging signal;
Controlling the position of the focus lens based on the focus signal,
The focus signal is sequentially acquired during a first scan operation for driving the focus lens in one direction, and the drive speed of the focus lens is changed according to the gradient of the focus signal with respect to the position of the focus lens.
A second driving unit configured to drive the focus lens in one direction after detecting a first focus lens position at which the focus signal obtained in the first scan operation reaches a peak when the first condition is satisfied; The position of the focus lens is controlled based on the position of the second focus lens at which the focus signal obtained in the second scan operation peaks .
The first condition is when the difference between the position of the first focus lens and the position of the focus lens corresponding to the focus signal before and after the first focus lens position exceeds a predetermined value. Control method. A program that causes a computer to execute control of an automatic focus adjustment device including an imaging unit that photoelectrically converts light that has passed through a photographing optical system including a focus lens to generate an imaging signal,
Generating a focus signal indicating the contrast of the subject from the imaging signal;
Controlling the position of the focus lens based on the focus signal,
The focus signal is sequentially acquired during a first scan operation for driving the focus lens in one direction, and the drive speed of the focus lens is changed according to the gradient of the focus signal with respect to the position of the focus lens.
A second driving unit configured to drive the focus lens in one direction after detecting a first focus lens position at which the focus signal obtained in the first scan operation reaches a peak when the first condition is satisfied; The position of the focus lens is controlled based on the position of the second focus lens at which the focus signal obtained in the second scan operation peaks .
The program according to claim 1, wherein the first condition is a case where a difference between the first focus lens position and the position of the focus lens corresponding to the focus signals before and after the first focus lens position exceeds a predetermined value .

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