JP2002311325A - Automatic focusing device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic focusing device capable of focusing a subject existing on the closest side at a high speed by using an evaluation value calculated from the high frequency component of a picture signal. SOLUTION: A focusing area 94 is divided into a plurality of blocks (1 to 4) to detect the peak of the evaluation value concerning the respective blocks. When the moving direction of a lens in the case of AF search is a direction from infinity to vicinity, searching operation is finished when the peak of the evaluation value is detected in all the divided blocks, and a lens position corresponding to a peak detected finally is judged to be a focusing position. In the case of searching operation from vicinity to infinity, searching operation is finished when the peak of the evaluation value with respect to one of the plurality of blocks is detected, and the lens position corresponding to a peak detected first is judged to be a focusing position. Furthermore, the evaluation value of the area 94 before division is combined and the interruption judgment of searching operation is performed to attain high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focusing apparatus and a method therefor, and more particularly, to detecting a high-frequency component of an image based on an output signal from an image sensor, and using the detection result to perform auto-focusing. The present invention relates to a technique for performing AF) control.

[0002]

2. Description of the Related Art In a video camera which captures an image of a subject and outputs a video signal thereof, the video camera captures an image while moving a focus lens of a photographic optical system which acts on focus adjustment, and extracts a high-frequency component from the output video signal. To calculate an evaluation value for focusing. When the evaluation value increases as a result of the movement of the focus lens, the lens continues to be driven in the same direction, and when the evaluation value decreases with the movement of the lens, it is driven in the opposite direction to search for the peak of the evaluation value. That is, a so-called "hill climbing servo system" is employed.

In a digital still camera,
A “contrast AF method” is employed in which a focus lens is driven from a point close to an object to infinity and the focus lens is driven and focused where the evaluation value is maximized.

[0004]

The conventional contrast A
In the F method, when a plurality of subjects having different distances exist in a focus area, as a method of focusing on a subject intended by a photographer, JP-A-6-113187 and JP-A-7-168083 disclose a method. There has been proposed a method of selecting a focus area intended by a photographer from a plurality of focus areas provided in a screen and performing automatic focus adjustment on the selected focus area. Also, Japanese Patent Application Laid-Open No. H9-197252 discloses that after a focus lens position is once adjusted based on an evaluation value obtained from a certain area among a plurality of focus areas, an evaluation value increases in another area at the lens position. There has been proposed a method of detecting a tendency and focusing on the closest object.

However, these conventional methods aim at focusing only on an intended subject,
After focusing on a certain area, there is a problem that it takes a long time to focus because a process of searching for an object at a shorter distance is performed.

The present invention has been made in view of such circumstances, and has as its object to provide an automatic focus adjustment apparatus and method capable of focusing on a subject located closest to the nearest side at high speed. .

[0007]

In order to achieve the above object, the present invention has an image pickup means for converting an optical image of a subject incident through a lens into an electric signal, and an image output from the image pickup means. In an automatic focus adjustment device that adjusts a focal position of the lens based on an evaluation value indicating a sharpness of an image calculated using a signal, the device includes a focus which is a calculation target area of the evaluation value in a shooting screen. Focus area setting means for setting an area; block dividing means for dividing the focus area into a plurality of blocks; lens moving means for moving the lens within a focus adjustment area; and each lens moved by the lens moving means For each position, a contrast component of a subject is extracted from the image signal for each of the divided blocks. An evaluation value calculation means for calculating the evaluation value min, while controlling the search operation to obtain the evaluation value at each lens position while moving the lens,
Monitoring the evaluation value calculated for each of the plurality of blocks, and when a peak of the evaluation value is detected for blocks equal to or more than the number of blocks set according to the lens movement direction of the search operation among the plurality of blocks. Control means for interrupting the search operation, determining the lens position at which the evaluation value has a peak on the closest side as a focus position, and controlling the lens moving means to move the lens to the focus position; It is characterized by having.

According to the present invention, the focus area is divided into a plurality of blocks, and an evaluation value is obtained for each block.
The peak detection status of the evaluation value is monitored in each block. By dividing the focus area, the probability that a plurality of subjects having different distances are mixed in one block is reduced. In other words, it is highly likely that a plurality of subjects at different distances will be detected separately in different blocks,
The peaks of the evaluation values of the subjects at different distances can be detected individually (by blocks). In other words, it is desirable that the number of divisions of the focus area be set so as to have a block size suitable for such individual detection.

There are two types of lens movement directions (search directions) in the search operation for obtaining the evaluation value: a direction from infinity to infinity (NEAR direction) and a direction from infinity to infinity (FAR direction). In the case of the search operation in the NEAR direction, the search operation can be ended when the peak of the evaluation value is detected in all the divided blocks.

When the peak of the evaluation value is detected in all the blocks, it is unlikely that the peak of the subject is detected further closer to the position than the position. Therefore, the search operation is terminated at that time, and the lens position corresponding to the last detected peak or its vicinity can be determined as the focus position. In addition,
The lens position corresponding to the peak of the evaluation value may be obtained by interpolation or the like from the evaluation value discretely obtained at each predetermined movement interval, as well as the lens position at which the evaluation value is actually calculated.

When a search operation in the FAR direction is performed, the search operation is interrupted when a peak of the evaluation value is detected for any one of the plurality of divided blocks, and the search operation is performed first. The lens position corresponding to the detected peak or the vicinity thereof can be determined as the focus position.

As described above, by switching the number of blocks for detecting the peak of the evaluation value depending on the search direction, unnecessary search operations can be omitted, and it becomes possible to focus on the closest object at high speed.

According to another aspect of the present invention, there is provided an automatic focusing apparatus, wherein first searching means for obtaining an evaluation value at each position while moving in the focusing area at relatively large intervals, and the first searching means. After moving the lens near the position where the peak of the evaluation value obtained by the search means is detected, the lens is moved near the position where the peak is detected at a smaller interval than the first search means. Second search means for obtaining an evaluation value at each position, wherein during the search operation by the first search means, peak detection of the evaluation values for the plurality of blocks and determination of interruption of the search operation are executed. The second search means evaluates the vicinity of the lens position corresponding to the peak detected on the closest side among the peaks of the evaluation values detected in the search operation of the first search means. Run the operation of obtaining a value, it determines that the focus position of the lens position corresponding to the peak of the evaluation values obtained by the second search unit, is characterized by moving the lens to the focus position.

That is, first, a first search operation (rough search) with a large search point interval (search step) is performed, and the vicinity of the peak obtained as a result is subjected to a second search operation (fine search) with a small search step. When the AF method for performing a detailed search is adopted, the above-described peak detection determination of a plurality of blocks is performed in the first search operation to determine whether the search operation has been interrupted, and a peak position on the closest side is detected. Then, by the second search means,
An accurate focus position is obtained by searching the vicinity of the peak position in more detail. Thereby, the AF processing can be further speeded up.

An automatic focusing apparatus according to still another aspect of the present invention, in addition to the above-described configuration, means for calculating the evaluation value for the focus area before division, and calculating for the focus area before division. Interruption determination means for determining the interruption of the search operation based on the evaluation value obtained, the control means, when the search operation is interrupted by the interruption determination means, the evaluation value of the already detected evaluation value The lens position corresponding to the peak of the evaluation value detected on the closest side of the peak or the vicinity thereof is determined as the focus position, and the lens moving means is controlled so as to move the lens to the focus position. It is characterized by:

According to this aspect, it is determined whether or not the search operation can be interrupted by combining the peak detection status in the plurality of divided blocks and the evaluation value of the entire focus area before the division. As described above, when the closest object is detected in the search operation from infinity to the closest, the search operation is interrupted when the peak of the evaluation value is detected in all the blocks. If there is a block including a low-value portion and a peak of the evaluation value does not appear, the search operation may be continued to the nearest end. In this case, the search operation takes a long time.

In order to solve such a problem, the peak detection judgment of the evaluation value of each divided block and the evaluation value of the entire focus area before division are combined to determine whether the search operation can be interrupted. That is, when the evaluation value of the entire focus area at a lens position that is a certain distance from the lens position where the peak is detected is equal to or smaller than a predetermined threshold, the search operation is interrupted assuming that no subject exists closer to that. I do. This makes it possible to focus on the subject closest to the nearest side at a higher speed.

If there is no tendency to increase the evaluation value at a position that is at least a predetermined amount away from the end point (at least one of the closest end and infinity) of the focus adjustment area, it is assumed that the subject does not exist before that. The determination can be made, and the AF processing can be speeded up by interrupting the AF search at that time.

In order to provide a method for achieving the above object, the present invention converts an optical image of a subject incident through a lens into an electric signal by an image pickup means, and converts an image signal output from the image pickup means into an electric signal. Calculating an evaluation value indicating the sharpness of an image by using the obtained evaluation value, and adjusting the focal position of the lens based on the obtained evaluation value. Setting a focus area to be an area, dividing the focus area into a plurality of blocks, moving the lens within a focus adjustment area, and moving each of the lenses while moving the lens. An evaluation for extracting a contrast component of a subject from the image signal for each of the divided blocks and calculating the evaluation value from the contrast component A calculating step, a step of controlling a search operation for acquiring the evaluation value at each lens position while moving the lens, and monitoring an evaluation value calculated for each of the plurality of blocks; A step of interrupting the search operation when a peak of the evaluation value is detected for blocks equal to or more than the number of blocks set according to the lens movement direction of the search operation; and Is determined as an in-focus position, and the lens is moved to the in-focus position.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an automatic focusing apparatus and method according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an external view of a digital camera to which the present invention is applied. A photographing lens 12, a viewfinder window 14, a strobe light emitting unit 1
6, a shutter button 18 is provided on the top of the camera.
And a power switch 20. A memory card 24 is provided on the side of the camera opposite to the grip 22.
Is provided with a card slot 26 for mounting the card.

A variable focal length lens (for example, a zoom lens) is applied to the photographing lens 12.
A CCD image sensor (not shown in FIG. 1; described as 52 in FIG. 3; hereinafter, referred to as CCD) is disposed behind the image sensor. The shutter button 18 is divided into two stages depending on the position where the shutter button is pressed.
When 1 is pressed, automatic focusing (AF) and automatic exposure control (AE) are performed, and when S2, which is deeper than S1, is pressed, photographing operations for recording (exposure and reading) are performed. .

The power switch 20 is also used as a mode changeover switch.
"Shooting ON position" which is turned on in still image shooting mode,
And the "reproduction ON position" which is turned on in the reproduction mode.
You can switch positions. Instead of the power switch (hereinafter referred to as a power / mode switch) 20 as in the present embodiment, a power switch for only power ON / OFF and a mode switching means such as a mode dial for switching between a still image shooting mode and a reproduction mode. May be provided.

FIG. 2 is an external view of the back side of the digital camera 10. On the back of the digital camera 10, a finder 28, a liquid crystal monitor 30, a zoom switch 32, a cross button 34, a menu key 38, an execution key 40, and a cancel key 42 are provided. The liquid crystal monitor 30 is a display means that can be used as an electronic finder for confirming the angle of view during photographing, and can display a preview image of a photographed image, a reproduced image read from the memory card 24, and the like. Selection of menus using the cross button 34 and setting of various items in each menu are also performed using the display screen of the liquid crystal monitor 30.

The zoom switch 32 is composed of a lever switch that can be operated in the up and down direction. The switch is zoomed in the telephoto (TELE) direction by operating the switch upward, and is wide-angle (WIDE) by operating the switch downward. ) Zoom in the direction. The cross button 34 is a multi-function button capable of inputting four directions of up, down, left, and right. The cross button 34 is used as an operation button for instructing selection of various setting items on the menu screen and changing of setting contents. It is used as a means for instructing adjustment and forwarding / returning of a playback frame.

The menu key 38 is used to make a transition from the normal screen of each mode to the menu screen. The execution key 40 is used, for example, when confirming the selected contents or instructing execution (confirmation) of processing. The cancel key 42 is used to cancel (cancel) an item selected from the menu or to return to the previous operation state.

The photographer operates the zoom switch 32 to determine the angle of view while confirming the real-time image (through image) displayed on the viewfinder 28 or the liquid crystal monitor 30, and presses the shutter button 18 to perform photographing. .

FIG. 3 is a block diagram showing the internal configuration of the digital camera 10. The taking lens 12 includes a four-group inner-focus zoom lens including a fixed lens 44, a variable power lens 46A, a correction lens 46B, and a focus lens 48.

The zoom lens 46A and the correction lens 46B
The camera moves along the optical axis while the positional relationship between the two is regulated by a cam mechanism (not shown), and changes the focal length. In addition,
For convenience of description, a variable power optical system including a variable power lens 46A and a correction lens 46B will be referred to as a "zoom lens 46".

The light that has passed through the taking lens 12 is
After the light amount is adjusted by the above, the light enters the CCD 52. C
Photosensors are arranged in a plane on the light-receiving surface of the CD 52. The subject image formed on the light-receiving surface of the CCD 52 via the photographing lens 12 has a signal charge corresponding to the amount of incident light by each photosensor. Is converted to In addition, CCD
Reference numeral 52 denotes the charge accumulation time (shutter speed) of each photosensor according to the timing of the shutter gate pulse.
, Which is a so-called electronic shutter function.

The signal charge stored in each photo sensor is
The signals are sequentially read out as voltage signals (image signals) corresponding to the signal charges based on the pulses supplied from the CCD driver 54. The image signal output from the CCD 52 is sent to the analog processing unit 56. The analog processing unit 56 includes a signal processing circuit such as a sampling hold circuit, a color separation circuit, and a gain adjustment circuit. In the analog processing unit 56, correlated double sampling (CDS) processing,
Each of the G and B color signals is subjected to color separation processing, and the signal level of each color signal is adjusted (pre-white balance processing).

The signal output from the analog processing section 56 is converted into a digital signal by the A / D converter 58 and stored in the memory 60. The timing generator (TG) 62 gives a timing signal to the CCD driver 54, the analog processing unit 56, and the A / D converter 58 in accordance with a command from the CPU 64, and the circuits are synchronized by the timing signal. .

The data stored in the memory 60 is transmitted to the bus 6
6 to the signal processing section 68. Signal processing unit 68
Is a digital signal processor (D) including a luminance / color difference signal generation circuit, a gamma correction circuit, a sharpness correction circuit, a contrast correction circuit, a white balance correction circuit, and the like.
SP), and processes an image signal in accordance with a command from the CPU 64.

The image data input to the signal processing unit 68 includes a luminance signal (Y signal) and color difference signals (Cr, Cb signals).
After being converted to, and subjected to predetermined processing such as gamma correction, the data is stored in the memory 60. When displaying the captured image, the image data is read from the memory 60,
The data is transferred to the display memory 70. The data stored in the display memory 70 is a signal of a predetermined system for display (for example,
After being converted to an NTSC color composite video signal)
The data is output to the liquid crystal monitor (LCD) 30 via the D / A converter 72. Thus, the image content of the image data is displayed on the screen of the liquid crystal monitor 30.

The image data in the memory 60 is periodically rewritten by the image signal output from the CCD 52,
The video signal generated from the image data is transmitted to the liquid crystal monitor 3
By being supplied to 0, an image input via the CCD 52 is displayed on the liquid crystal monitor 30 in real time.

When the photographer operates the zoom switch 32, an instruction signal is input to the CPU 64,
Controls the zoom drive unit 74 based on the signal from the zoom switch 32 to move the zoom lens 46 in the tele (TELE) direction or the wide (WIDE) direction. Zoom drive 7
Reference numeral 4 includes a motor (not shown), and the zoom lens 46 is driven by the driving force of the motor. The position (zoom position) of the zoom lens 46 is detected by a zoom position sensor 76, and a detection signal from the sensor 76 is input to the CPU 64.

Similarly, the focus driving section 78 includes a motor (not shown), and the focus lens 48 moves back and forth along the optical axis by the driving force of the motor. The position of the focus lens 48 (focus position) is detected by a focus position sensor 80, and the detection signal of the sensor 80 is C
It is input to PU64.

When the still image shooting mode is set by the power / mode switch 20 and the shutter button 18 is "half-pressed" (S1 = ON), AE and AF processes are performed. That is, the CPU 64 controls the focus driving unit 78 to move the focus lens 48 to the in-focus position based on the result of the evaluation value calculation described later, and calculates the aperture diameter of the diaphragm 50 and the electronic shutter value of the CCD 52. The subject image is displayed as a moving image on the liquid crystal monitor 30 to follow the subject during AF.

When the shutter button 18 is fully pressed (S2 = ON), a photographing start instruction (release ON)
A signal is emitted. The CPU 64 detects a release ON signal and executes an imaging operation for recording. That is, CP
U64 performs exposure control based on the result of the AE operation,
A command is sent to the flash control circuit 82 as needed to control the light emission of the flash light emitting unit 16.

In this way, in response to the pressing operation of the shutter button 18, the capture of the image data for recording is started, and the required signal processing is performed. When the mode for compressing and recording image data is selected, the CPU 64 sends a command to the compression / expansion circuit 84. The compression / expansion circuit 84 compresses the image data taken into the memory 60 according to JPEG or another predetermined format.

The compressed image data is recorded on the memory card 24 via the card interface 86.
Mode for recording uncompressed image data (uncompressed mode)
Is selected, the compression processing by the compression / expansion circuit 84 is omitted, and the image data is recorded on the memory card 24 without being compressed.

In the digital camera 10 of the present embodiment, for example, smart media (So
lid-State Floppy Disk Card) is applied. The form of the recording medium is not limited to this, and may be a PC card, a compact flash (registered trademark), a magnetic disk, an optical disk, a magneto-optical disk, a memory stick, or the like.
Various media that can be read and written according to an electronic, magnetic, or optical method, or a combination thereof can be used. Signal processing means and interfaces corresponding to the medium used are applied. A configuration may be adopted in which a plurality of media can be mounted irrespective of different types or the same type of recording media. The means for storing images is not limited to a removable medium, but may be a recording medium (internal memory) built in the digital camera 10. In the case of storing images in the internal memory, a communication interface for transferring data to an external device such as a personal computer is provided.

When the reproduction mode is set by the power / mode switch 20, an image file is read from the memory card 24. The read image data is subjected to expansion processing by a compression / expansion circuit 84 as necessary, and output to the liquid crystal monitor 30 via the display memory 70.

The CPU 64 is a control section for controlling the entire circuits of the camera system. The CPU 64 controls the operation of the corresponding circuits based on input signals received from the power / mode switch 20, the shutter button 18, the zoom switch 32, and other operation units, and controls display on the liquid crystal monitor 30, auto focus (AF). Control and automatic exposure (AE) control are performed. Note that the memory 6
0 is also used as a work area of the CPU 64, and evaluation value data and other data necessary for calculation are stored in the memory 60.

Here, the auto focus control will be described. The image signal converted into a digital signal by the A / D converter 58 is input to the evaluation value calculation unit 88. The evaluation value calculation unit 88 includes a high frequency component extraction circuit 90 and an integration circuit 9
2, the G component data of the input image signal is sampled, and the AF detection target area (reference numeral 94 in FIG. 4) is used.
Hereinafter, it is referred to as a focus area. ), The absolute value of the high frequency component is extracted, and the absolute value data is integrated within the set area, and a value (corresponding to an evaluation value) obtained by the integration is provided to the CPU 64.

The target area for AF detection does not need to be the entire image area. As shown in FIG. 4, a partial area at the center of the image is set as the focus area 94. During the AF process, the CPU 64
While moving 8 from infinity to close (or from close to infinity) in the focus adjustment area, the contrast of the central part of the image is detected at a plurality of AF detection points (search points), and the evaluation value is calculated.

As the focal length of the taking lens 12 becomes longer and the aperture diameter of the diaphragm 50 becomes larger, the depth of field becomes shallower, and the amount of lens drive from infinity to close range increases. , The interval between AF detection points (search interval) is changed.

FIG. 5 shows the relationship between the focal length of the taking lens 12 and the focus adjustment area 300. FIG. 3 shows an example of the photographing lens 12 in which the focal length can be changed stepwise from 7 mm to 21 mm. As the focal length of the photographing lens 12 increases, the focus adjustment area 300 of the focus lens 48 increases. For example, focal length 7mm
In the case of, focus lens 4 from infinity to the nearest
The movable range of 8 is 8.17 μm, and the focus adjustment area 300 when the focal length is 21 mm is 735 μm.

The CPU 64 has an AF step width 302 indicating the width of the lens position (search point) for calculating the evaluation value and the number of steps (detection) in accordance with the focus adjustment area 300 which varies according to the focal length of the photographing lens 12. Points).

The number of focus steps may be such that the focus adjustment area 300 at each focal length is equally divided by the AF step width 302, or the AF step width 30 on the short distance (closest limit) side.
2 may be set to be shorter than the infinity side, to increase the number of search points on the short distance side, and to increase the focus accuracy.

In this way, the evaluation value calculated at each search point is integrated, the lens position at which the evaluation value reaches a peak (maximum value or local maximum value) is determined as the focus position, and the focus lens is located at the obtained focus position. The focus drive unit 78 is controlled so as to move the focus drive unit 48.

FIG. 6 shows an example in which evaluation values are obtained by AF search. When only one main subject exists in the focus area 94, only one peak of the evaluation value appears as shown in FIG. In this case, the lens position (P) at which the peak is detected is set as the focus position, and the focus lens 48 may be moved here. In contrast,
As shown in FIG. 7, when there are a plurality of subjects in the focus area 94, it is not possible to focus on both subjects, and it is necessary to focus on one of the subjects. Generally, when a plurality of subjects having different distances are detected, focusing is performed on the subject on the closest side.

FIG. 8 shows an example of a result of obtaining an evaluation value when a plurality of subjects exist in the focus area 94. As shown in FIG. 7, when there are a plurality of subjects in the focus area 94, there are a plurality of peaks in the evaluation value curve. If one mountain is detected and the AF search is terminated, only one mountain can be detected.
Multiple mountains cannot be detected. For example, in FIG. 8, if the AF search operation is started from the infinity side and the AF search operation is ended when the peak at the infinity side is detected, another peak on the close side can be detected. Therefore, it is not possible to focus on the main subject on the close side.

Therefore, in the present embodiment, an efficient AF
In order to realize the search operation, as shown in FIG. 9, the focus area 94 is divided into a plurality of regions (blocks) (four in FIG. 9), and evaluation values are obtained for each divided block. Of course, the shape, size, division method, and division number of the focus area 94 are not limited to the example shown in FIG. The shape and division form of the entire focus area are designed so that subjects at different distances are detected in different blocks as much as possible.

FIG. 10 shows an example of an evaluation value obtained from each block of the focus area 94 divided into four blocks shown in FIG. 1 includes only a short-distance subject, and FIG.
As shown by 0, the peak of the evaluation value appears on the short distance side.
On the other hand, since the block including only the subject at a long distance, the peak of the evaluation value appears on the long distance side. When the search operation is performed from the infinity side, the AF search is terminated when peaks are detected in all of the divided blocks, and
The peak position detected on the closest side is taken as the focus position,
The focus lens 48 is driven to the position. According to this method, regardless of whether a plurality of subjects having different distances exist in the focus area 94 or not.
It is possible to focus on the closest object at high speed.

When the AF search is executed from the closest side, it is only necessary to focus on the peak position detected first. Therefore, when the peak of the evaluation value is detected in at least one of the divided blocks. What is necessary is just to control so as to end the AF search. In this way, by switching the number of blocks for which the peak is detected depending on the AF search direction, it is possible to perform AF at higher speed.

FIG. 11 is a flowchart at the time of AF in this example. Pressing the shutter button 18 halfway (S
1 = ON), the AF process starts, the CPU
In step 64, the focus area 94 is first set, and the focus area 94 is divided into n blocks (step S101).

Next, the current value of the focal length of the photographing lens 12, that is, information on the current zoom position (ZOOMPOS) is obtained (step S102). After step S102, the process proceeds to step S104 to perform an arithmetic process for determining the AF search direction. In the present embodiment, the AF search direction is determined according to the relationship between the current focus position and the focus adjustment area 300. When the current focus position is on the far side (infinity side) from the intermediate position M of the focus adjustment area 300, first, the focus is driven to infinity, and the AF search is performed from infinity to a close distance (NEAR direction search). Execute Conversely, when the current focus position is closer (closer) than the intermediate position M, first,
The focus is driven to the closest side, and an AF search (FAR direction search) is executed from the closest limit to infinity. Judging from the current focus position, the AF search direction is automatically selected such that the closer focus end is set as the initial position (start position) of the search, so that the average time for driving to the search start position can be reduced.

The method for determining the search direction is not limited to the above example. For example, when considering the shooting distance of a camera equipped with a zoom function, the subject is often far away on the telephoto side, and is very close on the wide side. From this viewpoint, by changing the focus search direction according to the focal length, high-speed focus search can be performed. When the current zoom position is on the wide side, the search start position is set to the closest side, and a search direction from the closest to infinity is selected. On the other hand, when the current zoom position is on the tele side, there is a mode in which the search start position is set to the infinity side, and a search direction from infinity to the closest is selected.

It is also preferable that the lens moving direction during the focus adjustment operation is determined based on the current focus position and zoom position. In this case, there is a mode in which a table that defines a lens moving direction corresponding to a combination of a focus position and a zoom position is used.

When the AF search direction is determined in step S104, a process for setting a threshold value m for the number of peak detection blocks is performed based on the determination (step S10).
6). When the search operation from infinity to the closest side is selected, the threshold m is set to the number of divisions “n” of the focus area 94 (total number of divided blocks, n in the example of FIG. 9).
= 4) is set. When the search operation from the closest to the infinity side is selected, “1” is set to the threshold value m. Thereafter, the process proceeds to step S108, where the focus lens 48 is moved to the search initial position.

In the following step S 110, an evaluation value at the current focus stage (search point) is calculated, and the obtained evaluation value is input to the CPU 64. CP
U64 stores the evaluation value at the search point in memory 60.

Then, the process proceeds to a step S122, wherein a peak detection judgment process is performed for the n blocks. FIG. 12 shows the contents of this determination processing. When the subroutine of the peak detection determination process shown in the figure starts, first, it is determined whether or not the evaluation value continuously decreases a predetermined number of times (step S2)
10). If a YES determination is obtained in step S210, the process proceeds to step S212. In step S212, it is determined whether the difference between the maximum value (AFmax) and the minimum value (AFmin) of the evaluation values calculated by the AF search operation is larger than a predetermined value L. If the difference between the evaluation values is larger than the predetermined value L (when YES is determined), step S21 is performed.
4. Go to step 4 and set the "Peak flag" to ON, and set the focus position (peak position) where the peak was detected.
Is updated. Thereafter, the process returns to the flowchart shown in FIG.

When a NO determination is obtained in step S212 shown in FIG. 12 or a NO determination is obtained in step S210, the process returns to the flowchart shown in FIG.

Returning to the flowchart of FIG. 11, in step S124, the number of blocks for which peaks are detected is compared with a threshold value m. The number of blocks for which peak detection is performed is a threshold value m
If it is smaller than (when NO is determined in step S124), the process proceeds to step S126, and the focus lens 48
Is determined whether or not has reached the position of the last stage of the search point.

If a NO determination is obtained in step S126, the process proceeds to step S128, in which the focus lens 48 is moved by one search step (AF step width 302) from the current focus stage, and returns to step S110. . In this manner, the evaluation value is moved to the next search point, and the evaluation value is calculated from the frame image data having different focus positions. The processing of steps S110 to S128 is repeated for each point in the focus adjustment area 300, and the evaluation value of each point is sequentially acquired.

When the number of blocks for which peak detection is performed is equal to or larger than the threshold value m in step S124 (step S124).
124 (YES) or step S126
If the focus lens 48 has reached the position of the last stage in step S <b> 130, the process proceeds to step S <b> 130. In step S130, a position (focus position) at which the maximum evaluation value is obtained is obtained from the result of the evaluation value obtained at each search point, and the focus lens 48 is moved to the focus position.

That is, when the search direction is the NEAR direction, the threshold value m is set to "1", so that when a peak is detected in any one of the n divided blocks, the determination in step S124 is YES. The peak position of the evaluation value detected first is determined as the focus position. When the search direction is the FAR direction, the threshold value m is set to “n”, so that when all the n divided blocks have peaks detected, the determination in step S124 is YES. In this case, the last detected peak position is determined as the focus position, and the focus lens 48 is moved to this position. If the in-focus position where the peak of the evaluation value is obtained cannot be detected, the focus lens 48 is moved to a predetermined pan focus position (for example, a predetermined position such as a position where the object distance is 3 m). .

In step S130, when the focus lens 48 is driven to the in-focus position, the focus lens 4 is released until the shutter button 18 is half-pressed.
8 is held at the in-focus position. At the same time, the operation of the evaluation value calculation unit 88 is stopped, and the photographing / recording is permitted (step S132). Thus, the automatic focus adjustment processing ends.

When the photographing and recording permission state is obtained, the CPU
The operation state of the shutter button 18 is confirmed by 64, and in response to the full depression of the shutter button 18, the subject is imaged at the current zoom position and the focused focus position, and image data that has undergone predetermined signal processing is attached. The information is recorded on the memory card 24 together with the information.

Next, a description will be given of a control example capable of achieving a higher speed of the AF processing. As described in FIG. 5, as the focal length of the taking lens 12 increases, the focus adjustment area 300
The focus feed amount (the number of motor drive pulses) (from infinity to a close distance) increases, and the AF time becomes longer. Therefore, first, a "rough search" for obtaining an evaluation value in an AF search step in which the focus feed amount (search interval) is increased is performed, and when an approximate in-focus position is detected by the rough search, the focus feed amount is further reduced in a nearby area. It is preferable to perform a “detailed search” for obtaining an evaluation value in the search step performed.

FIG. 13 is a conceptual diagram of the rough search and the detailed search. For example, it is assumed that the focus feed amount from infinity to close distance is 240 pulses, the number of focus feed pulses during rough search is set to 20, and the number of focus feed pulses during detailed search is set to 2 pulses. According to the figure, first, a rough search is started from infinity in the NEAR direction. In the rough search, a search point is changed every 20 pulses, an evaluation value is calculated at each point, and a peak detection process in each block as described with reference to FIGS. 11 and 12 is performed.

When a peak is detected in the rough search and, for example, the interruption of the evaluation value acquisition processing is determined at the position of 100 pulses, the focus is moved to the initial position (Pds) of the detailed search, from which the detailed search is performed in the FAR direction. Be started. In the detailed search, the search point is changed every two pulses, the evaluation value is calculated at each point, and after the peak is detected, if the evaluation value continuously decreases a predetermined number of times, it is determined that the evaluation value acquisition processing is to be interrupted, and the peak position ( The focus lens 48 is driven to the (focus position).

FIG. 14 is a flowchart of the AF control combining the rough search and the detailed search. In the figure, steps that are the same as or similar to those in FIG. 11 are given the same step numbers, and descriptions thereof are omitted. However, step S12
In 8, it is assumed that the focus lens 48 is driven at a search interval of 20 pulse steps.

In step S124, when it is detected that the number of blocks for which the peak is detected is equal to or greater than the threshold value m (when YES is determined), or when the final position of the focus stage is reached in step S126 (when peak detection is performed in the rough search). If the number of blocks has reached the final focus stage without reaching the threshold value m), the process proceeds to step S140. In step S140, an operation for obtaining a range of the detailed search based on the result of the rough search is performed. The range of the detailed search is, for example, a predetermined range before and after the peak corresponding position of the evaluation value detected by the rough search. If no peak of the evaluation value is detected in the rough search, the entire range of the focus adjustment area is set as the detailed search range, and the detailed search is started from a predetermined initial position such as the closest (or infinity).

Next, in step S142, a focus area is set in the detailed search. For example, a block in which the nearest peak is detected in the rough search processing is selected as a focus area for the detailed search. Thereafter, a process of driving the focus lens 48 to the detailed search start position (detailed search initial position) is performed according to the detailed search range obtained in step S140 (step S144). Thus, the detailed search starts, and the evaluation value at the search point is calculated (step S146). The obtained evaluation value is input to the CPU 64, and the CPU 64 stores the evaluation value at the search point in the memory 60 together with the lens position.

Then, the process proceeds to a step S148, wherein a process for determining whether or not to suspend the AF search (detailed search) is performed. FIG. 15 shows the contents of the “interruption determination”.

When the interruption determination processing shown in FIG. 15 starts, first, a table value “C_TABLE” corresponding to the current focal length [ZOOMPOS] is set in the register C (step S310). This is a process of setting an interruption determination value C as a criterion for determining to suspend the AF search when the evaluation value calculated at each focus stage (search point) continuously decreases. .

The interruption determination value C is set to the same numerical value as the number of focus steps ("4" in the example of FIG. 5) or a value close to it on the short focus side (wide side), so that the interruption processing is not substantially performed. Is set to In addition, the interruption determination value C becomes larger as approaching the long focal length side (tele side),
It is set to an integer value of about 50% to 30% of the number of focus steps.

Next, the flow advances to step S312 to determine whether or not the obtained evaluation value has decreased. If the evaluation value has not decreased (NO determination), the continuation of the AF search is determined (step S322), the process exits this subroutine, and returns to the flowchart of FIG.

When it is determined in step S312 in FIG. 15 that the evaluation value has decreased (when the determination is YES), register n (initial value is set to n = 0. Note that "n" is the focus. 1 is added to the value of the parameter (independent of the number of divisions of the area 94) (step S3).
14) In the following step S316, it is determined whether or not the value of the register n exceeds the value of the register C. If the value of the register n is equal to or less than the value of the register C (NO determination), the process proceeds to step S322 to determine continuation of the AF search, and returns to the flowchart of FIG. Thus, the AF search is continued until the evaluation value continuously decreases C times.

YES in step S316 in FIG.
When the determination is obtained, that is, when it is detected that the evaluation value continuously decreases C times, the process proceeds to step S318. In step S318, it is determined whether the difference between the maximum value (AFmax) and the minimum value (AFmin) of the evaluation values calculated by the AF search operation is larger than a predetermined value K. When the difference between the evaluation values is larger than the predetermined value K (when YES is determined), it indicates that there is a predetermined contrast, so that
The interruption of the AF search is determined (step S320).
If the difference between the evaluation values is equal to or smaller than the predetermined value K (NO determination), the process proceeds to step S322, and continuation of the AF search is determined.

When "interruption" or "continuation" is determined in step S320 or S322, the present subroutine ends, and the process returns to the flowchart in FIG.

Thereafter, as shown in FIG. 14, based on the result of the interruption determination processing (step S148), the CPU 6
4 judges whether the AF search is interrupted or continued (step S
150). When the determination of “continue” is obtained in step S150, the process proceeds to step S152, and it is determined whether the final position of the search point has been reached.

If a NO determination is obtained in step S152, the flow advances to step S154 to move the focus lens 48 by one step (two pulses) of the AF search step from the current focus position.
Return to 46. In this manner, the evaluation value is moved to the next search point, and the evaluation value is calculated from the frame image data having different focus positions. The processing of steps S146 to S154 is repeated for each point in the detailed search range, and the evaluation value of each search point is obtained.

In step S152, the focus lens 48
Has reached the final position of the search point, or when the determination of “interruption” has been obtained in step S150, the process proceeds to step S160. In step S160, a position at which the evaluation value is maximized is obtained from the result of the evaluation value obtained at each point, and the focus lens 48 is moved to that position (in-focus position). In this manner, a state where photographing and recording are permitted is set (step S162), and the automatic focus adjustment processing ends.

Next, another control example of the AF processing will be described.
As another method for searching from the infinity side, an evaluation value for each divided block and a focus area 9 before division are set.
4 There is also a method of comparing with the evaluation value of the whole. When detecting the closest object on the basis of only the divided blocks, if an object with low contrast exists in any of the blocks,
The peak is not detected, and the search is performed up to the nearest point, which takes time.

In order to solve this problem, the closest object is detected by combining the above-mentioned method using the evaluation value of each divided block and the method described later using the evaluation value of the entire focus area before division.

A graph (FIG. 8) of the evaluation value when a plurality of objects having different distances exist in the entire focus area 94 before the division, and a case where only one object exists in the focus area 94 (other distances are different). As shown in FIG. 6, when the peak of the evaluation value is detected by the AF search operation from infinity to the closest distance, the graph is further compared with the evaluation value graph of FIG. When the evaluation value is obtained by moving the lens in the same direction, when the focus lens 48 is separated from the peak position P by a certain distance d, the evaluation value decreases to near the zero level. On the other hand, as shown in FIG. When I do it,
After the detection of the first peak, the evaluation value does not decrease to near the zero level but starts to increase again.

By paying attention to this fact, if the evaluation value at a position separated by a certain distance d from the lens position where the peak of the evaluation value is detected is equal to or less than a predetermined threshold value TH, it is determined that the subject does not exist beyond that. Then, the AF search is completed, and the focus lens 48 is moved to the first detected peak position.
Drive.

On the other hand, if the evaluation value at a position separated by a certain distance d from the lens position at which the peak of the evaluation value is detected is a value larger than the predetermined threshold value TH, another subject may exist ahead of it. The NEAR side AF
Continue the search operation. Note that the distance d from the peak position P is preferably set to about 10 to 20 times the allowable circle of confusion. If a plurality of peaks are detected by the AF search operation, the closest peak position is determined as the focus position.

By the way, the noise of the image pickup signal occurs when the subject is dark or the like, and as shown in FIG.
A situation can occur in which the evaluation value does not fall below the threshold value TH. However, as can be seen by comparing FIG. 16 and FIG. 8, when another subject exists on the close side (FIG. 8)
Indicates that the evaluation value tends to increase from a position slightly before the nearest point (closest end). On the other hand, if the evaluation value does not decrease due to noise or the like (FIG. 16), the evaluation value does not change to an increasing tendency even if the evaluation value is at least a certain distance w from the closest distance.

Therefore, it is possible to determine whether another subject exists on the close side by determining whether or not the evaluation value is in the increasing direction at a distance more than a certain distance w from the closest. If there is no evaluation value in the increasing direction at a distance more than a certain distance w from the closest distance, it is determined that no subject exists on the close side and A
The F search operation is completed, and focus driving is performed to the lens position where the peak is detected. Note that the fixed distance w is preferably set to be about 5 to 10 times the permissible circle of confusion. FIG.
In the AF search operation in the FAR direction, similarly, if the evaluation value does not tend to increase at a position separated from the infinity by a certain distance w, it can be determined that the subject does not exist on the infinity side.

FIG. 17 is a flowchart of an AF process based on a combination of a divided block and a focus area before division. In the figure, the same or similar processing as in FIG. 11 is denoted by the same step number, and the description is omitted. After moving the focus lens 48 to the search initial position in step S108 of FIG.
Then, the process proceeds to step S10, where an evaluation value is calculated for each divided block and the entire focus area 94 before division (hereinafter, referred to as "area before division"). The sum of all the evaluation values for each divided block corresponds to the evaluation value of the pre-division area. Subsequently, an interruption determination (2) process is performed for the pre-division area (step S112). FIG. 18 shows a flowchart of a subroutine of the interruption determination (2) processing. When the interruption determination (2) process starts, first,
It is determined whether a peak at which the evaluation value changes from increasing to decreasing is detected (step S510). This determination is made based on the state of a “peak presence flag” described later.

If no peak is detected in step S510 (NO), the process advances to step S512 to determine whether the evaluation value has decreased. Step S
If a negative determination is obtained in 512, continuation of the evaluation value acquisition process is determined (step S518), and this subroutine is terminated, and the flow returns to the flowchart of FIG.

If it is detected in step S512 in FIG. 18 that the evaluation value has decreased, the flow branches to step S514. In step S514, it is determined whether or not the evaluation value before the decrease has been increasing. Step S5
If a YES determination is made in step 14, the maximum (AFmax) and minimum (AFmax) evaluation values calculated by the AF search operation are calculated.
It is determined whether or not the difference from (min) is greater than a predetermined value K '(step S515). If a YES determination is obtained in step S515, the "peak presence flag" is set to O.
N is set, and the data of the variable P indicating the focus position (peak position) at which the peak is detected is updated (step S516). After step S516, or if a NO determination is obtained in step S515, the process proceeds to step S518, and continuation of the evaluation value acquisition process is determined.

When the "peak presence flag" is set to ON, a YES determination is made in step S510. In this case, the process proceeds to step S520, and it is determined whether the search direction is the NEAR direction. When the search direction is the NEAR direction (when YES is determined), it is determined whether or not the current focus position (search point) is closer than a predetermined distance (d) from the peak position P to the nearest side ( Step S522). If the current position is within a predetermined distance d from the peak position P (NO determination), step S52 is performed.
Then, it is determined whether the number of remaining detection points in the search direction is smaller than a predetermined value (u). This predetermined value u is a value corresponding to the distance w described in FIG.

In step S528, when the number of remaining detection points is equal to or greater than the predetermined value u (NO determination), continuation of the evaluation value acquisition processing is determined (step S532), and the process returns to the flowchart of FIG. On the other hand, if a YES determination is obtained in step S528 in FIG. 18, the process proceeds to step S530, and it is determined whether the evaluation value has increased.

If an increase in the evaluation value is detected in step S530 (when YES is determined), the flow advances to step S532 to determine continuation of the evaluation value acquisition process (step S53).
2) If the evaluation value has not increased in step S530 (NO determination), the process proceeds to step S536 to determine the interruption of the evaluation value acquisition process, and returns to the flowchart of FIG.

If the current focus position is closer than the peak position P by a predetermined distance d in step S522 in FIG. 18 (YES determination), the flow branches to step S524. In step S524, it is determined whether the evaluation value at the current focus position is smaller than a predetermined threshold value TH.

If the evaluation value is equal to or larger than the threshold value TH in step S524 (when NO is determined), the process proceeds to step S528 in consideration of the possibility that the subject exists closer to the current position. On the other hand, when the evaluation value is smaller than the threshold value TH in step S524 (when YES is determined), it is determined that the subject does not exist closer to the current position than the current position, and the interruption of the evaluation value acquisition process is determined ( Step S536).

If the determination in step S520 is NO, that is, if the search direction is the FAR direction, step S520
Proceed to 526. In step S526, it is determined whether the evaluation value has continuously decreased a predetermined number of times. A reference value serving as a criterion for determining the number of continuous reductions is appropriately set in consideration of the depth of field and the like.

If a negative determination is obtained in step S526, the flow advances to step S528, and a determination of interruption or continuation is made in steps S528 to S536 described above. On the other hand, if a YES determination is obtained in step S526, the process advances to step S538 to determine interruption of the evaluation value acquisition process, and the process returns to the flowchart in FIG. By following the interruption determination (2) processing shown in FIG.
In any of the AR direction and the FAR direction, the peak of the evaluation value corresponding to the subject can be detected accurately and at high speed, and the AF processing can be speeded up.

When the interruption determination (2) process described with reference to FIG. 18 is completed and the process returns to the flowchart in FIG. 17, the process proceeds to step S114. In step S114, interruption or continuation of the search operation is determined based on the result of the above-described interruption determination (2) processing. When the determination of “interruption” is obtained, the AF search operation is terminated and the process proceeds to step S130, and the focus lens 48 is moved to a lens position where the maximum evaluation value is obtained.

On the other hand, in step S114, "continue"
Is obtained, the process proceeds to step S122. Subsequent processing is as described with reference to FIGS.

In order to further increase the speed of AF, the rough search and the detailed search described with reference to FIGS.
An aspect in which a control method using a combination of the evaluation value of each divided block and the evaluation value of the pre-division area in F control will be described. FIG. 19 is a flowchart of the operation. In the figure, the same or similar steps as those in FIG. 14 are denoted by the same step numbers, and the description thereof is omitted.

In step S108 in FIG. 19, after moving the focus lens 48 to the initial search position, the flow advances to step S110 to calculate an evaluation value for each divided block and the pre-division area. Next, an interruption determination process (2) is performed on the area before the division. The content of the interruption determination process (2) is as described in FIG.

In the following step S114, interruption or continuation of the search operation is determined based on the result of the interruption determination (2) processing. When the determination of “interruption” is obtained, the rough search operation ends, and the process proceeds to step S140. On the other hand, when the determination of “continuation” is obtained in step S114, the process proceeds to step S122.

After calculating the detailed search range in step S140, the flow advances to step S143 to set a focus area in the detailed search. Here, the area before division is selected as the focus area.
Subsequent processing is as described in FIG.

[0110]

As described above, according to the present invention, the focus area is divided into a plurality of blocks, and the peak of the evaluation value is detected for each of the divided blocks.
The search operation is interrupted when the peak of the evaluation value is detected in blocks equal to or greater than the number of blocks set according to the search direction, so that the subject closest to the nearest side is focused at high speed. be able to.

Further, the evaluation value is calculated for the entire focus area before the division, and the evaluation value of the entire focus area is combined with the evaluation values of the plurality of divided blocks to determine whether to interrupt the search operation. Speedup can be achieved.

[Brief description of the drawings]

FIG. 1 is a front external view of a digital camera according to an embodiment of the present invention.

FIG. 2 is a rear view of the digital camera shown in FIG. 1;

FIG. 3 is a block diagram showing an internal configuration of the digital camera of the present embodiment.

FIG. 4 is a diagram showing an example of a focus area set at the center of the screen;

FIG. 5 is a diagram showing a change in an AF search step width according to a zoom position and a focus position.

FIG. 6 is a graph showing an example of an evaluation value that changes as the focus lens moves.

FIG. 7 is a diagram showing a state in which a plurality of subjects are present in a focus area.

FIG. 8 is a graph showing an example of an evaluation value that changes with movement of a focus lens when a plurality of subjects exist.

FIG. 9 is a diagram showing an example of dividing a focus area.

FIG. 10 is a diagram illustrating an example of an evaluation value calculated for each divided block.

FIG. 11 is a flowchart illustrating a procedure of AF control according to the present embodiment.

FIG. 12 is a flowchart of a peak detection determination process in FIG. 11;

FIG. 13 is a conceptual diagram of an AF method combining a rough search and a detailed search.

FIG. 14 is a flowchart showing a control procedure of an AF method for performing a rough search and a detailed search.

FIG. 15 is a flowchart of an interruption determination process in FIG. 14;

FIG. 16 is a graph illustrating a phenomenon in which the evaluation value does not decrease due to the influence of noise or the like.

FIG. 17 is a flowchart illustrating a control procedure of an AF process based on a combination of a divided block and a focus area before the division.

FIG. 18 is a flowchart of an interruption determination (2) process in FIG. 17;

FIG. 19 is a flowchart showing a control procedure in the case of applying AF processing by combining a divided block and a focus area before division in an AF method for performing a rough search and a detailed search.

[Explanation of symbols]

10 digital camera, 12 photographing lens, 18 shutter button, 48 focus lens, 52 CCD
(Imaging means), 64 CPU (focus area setting means, block dividing means, control means, interruption determining means), 7
8 focus drive unit (lens moving means), 88 evaluation value calculation unit (evaluation value calculation means), 94 focus area

Continued on the front page F term (reference) 2H011 AA01 BA31 BB04 2H051 BA45 BA47 CB22 DA07 DA31 DB01 5C022 AB29 AB30 AB44 AC03 AC42 AC54 AC74

Claims (8)

[Claims] An evaluation value indicating an image sharpness calculated using an image signal output from the imaging unit, the imaging unit comprising: an imaging unit configured to convert an optical image of a subject incident through a lens into an electric signal. An automatic focus adjustment device that adjusts a focal position of the lens based on a focus area setting unit that sets a focus area to be a calculation target area of the evaluation value in a shooting screen; A block dividing unit that divides the lens into blocks; a lens moving unit that moves the lens within the focus adjustment area; and a lens position that is moved by the lens moving unit. Evaluation value calculation means for extracting a contrast component of the subject and calculating the evaluation value from the contrast component; While controlling a search operation for acquiring the evaluation value at each lens position while moving a lens, monitoring the evaluation value calculated for each of the plurality of blocks and monitoring the lens movement direction of the search operation among the plurality of blocks. When the peak of the evaluation value is detected for blocks equal to or more than the number of blocks set according to the above, the search operation is interrupted, and the lens position where the evaluation value becomes the peak on the closest side is determined as the in-focus position. Control means for controlling the lens moving means so as to move the lens to a focus position. 2. In the case of a search operation in which an evaluation value is calculated while moving a lens from infinity to a close distance, the same number as the number of blocks of the focus area is set as the number of blocks. When the peak of the evaluation value is detected for all the blocks, the search operation is interrupted, and the lens position corresponding to the last detected peak or the vicinity thereof is determined as the in-focus position. The automatic focusing device according to claim 1. 3. In the case of a search operation in which an evaluation value is calculated while moving a lens from a closest point to an infinity point, “1” is set as the number of blocks, and the control unit controls the plurality of divided blocks. When the peak of the evaluation value is detected for at least one of the blocks, the search operation is interrupted, and the lens position corresponding to the first detected peak or its vicinity is determined to be the focus position. The automatic focusing device according to claim 1, wherein 4. The automatic focusing device according to claim 1, wherein the automatic focusing device acquires an evaluation value at each position while moving in the focusing region at relatively large intervals. After moving the lens to a position near a position where a peak of the evaluation value obtained by the first search means is detected,
A second search means for obtaining an evaluation value at each position while moving in the vicinity of the position where the peak is detected at a smaller interval than the first search means, and a search by the first search means. During the operation, peak detection of the evaluation values for the plurality of blocks and determination of interruption of the search operation are executed, and the peak of the evaluation values detected in the search operation of the first search means is detected on the closest side. An operation of acquiring an evaluation value by the second search means is performed in the vicinity of the lens position corresponding to the detected peak, and the lens position corresponding to the peak of the evaluation value obtained by the second search means is defined as an in-focus position. An automatic focus adjustment device, which determines and moves the lens to the in-focus position. 5. The automatic focus adjustment device according to claim 1, wherein the device calculates the evaluation value for the focus area before the division, and the focus before the division. And interruption determination means for determining interruption of the search operation based on the evaluation value calculated for the area.If the search operation is interrupted by the interruption determination means, A lens position corresponding to the peak of the evaluation value detected on the closest side among the peaks of the evaluation value or the vicinity thereof is determined as a focus position, and the lens moving means is configured to move the lens to the focus position. An automatic focus adjustment device characterized by controlling the following. 6. The automatic focus adjustment device according to claim 5, wherein the interruption determination unit is arranged at a position separated by a predetermined distance from a lens position at which a peak of an evaluation value calculated for the focus area before the division is obtained. An automatic focus adjustment device, which compares an evaluation value of the search result with a predetermined threshold value, and when the evaluation value is equal to or less than the threshold value, determines that the search operation is interrupted. 7. The automatic focus adjustment device according to claim 5, wherein the interruption determination unit changes the evaluation value of the entire focus area at a lens position separated from an end point of the focus adjustment area by a predetermined amount or more. An automatic focus adjustment device having an evaluation value change detecting means for detecting a search operation, and determining that the search operation is to be interrupted when the evaluation value change detecting means does not detect an increasing tendency of the evaluation value. . 8. An optical image of a subject incident through a lens is converted into an electric signal by an imaging unit, and an evaluation value indicating a sharpness of an image is calculated using an image signal output from the imaging unit. In the automatic focus adjustment method for adjusting the focal position of the lens based on the obtained evaluation value, the method includes: setting a focus area to be a calculation target area of the evaluation value in a shooting screen; Dividing the lens into a plurality of blocks; moving the lens within a focus adjustment area; and moving the lens for each lens position. For each of the divided blocks, a contrast component of a subject from the image signal for each of the divided blocks. Extracting, and calculating an evaluation value from the contrast component, an evaluation value calculating step; and moving each of the lens positions while moving the lens. Controlling the search operation for obtaining the evaluation value; and monitoring the evaluation value calculated for each of the plurality of blocks, and setting the number of blocks in the plurality of blocks to be set according to a lens moving direction of the search operation. A step of interrupting the search operation when a peak of the evaluation value is detected for the above blocks; and determining a lens position at which the evaluation value has a peak on the closest side as an in-focus position. Moving the lens.