JP3595558B2 - Camera and automatic focusing device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a camera that automatically adjusts the focus based on information of a video signal that changes according to focus and defocus. And automatic focus adjustment device It is about.
[0002]
[Prior art]
In recent years, as cameras have become smaller and lighter, the volume and weight occupied by a lens unit and an automatic focusing unit have been rapidly decreasing.
[0003]
In a "VTR integrated camera" in which a television camera and a video tape recorder are integrated, an optical signal that has passed through an optical system including a lens and the like is converted into an electric signal by a photographing element in the camera section, and this is converted into a tape recorder. It is becoming common to reduce the volume and weight by also using the parts as well as recording the images in an automatic focus adjustment (hereinafter also referred to as “AF”).
[0004]
FIG. 13 is a view for explaining an optical system of the VTR-integrated camera 10. Reference numeral 101 denotes a first lens group (hereinafter, also referred to as a "focus lens") for performing focus adjustment, and reference numeral 102 denotes a second lens unit for performing zooming. 103 is a third lens group that corrects the movement of the focal plane that changes with the movement of the zoom lens 102, 104 is an aperture, and 105 is an imaging surface for capturing an optical image. A fourth lens group for accurately forming an image on the lens 106. The optical image information received by the imaging surface 106 is converted into a video signal which is an electric signal. The first lens group 101 moves in parallel with the optical axis L and forms an image on an imaging surface 106 for a certain subject. It is generally known that a video signal obtained as an output of the imaging surface 106 has a higher frequency component as the optical system approaches the object to be in focus. The high frequency component of this video signal can be converted to a focal voltage FV. FIG. 9 shows the change of the focus voltage FV.
[0005]
In FIG. 9, reference numeral 801 denotes a change curve of the focus voltage FV, and reference numerals 802 and 803 denote arrows indicating the movement of the focus voltage FV from the out-of-focus state of the first lens group 101 to the in-focus state. The focus voltage FV becomes maximum at the focal point Pf, and shows a low value at other points. In particular, in a state of a large blur (point Po farthest from the focal point Pf), the focal voltage FV becomes the lowest value, and even if the first lens group 101 moves, the value of the focal voltage FV hardly changes. Will not be.
[0006]
A method of changing the focus voltage FV (arrows 802 and 803) will be described with reference to FIG. This figure explains a method called AF control of hill climbing. In the present description, the lens groups 101 to 103 and 105 are controlled by a control element such as a microcomputer, and the focus lens 101 is turned off. The following description is based on the premise that control is started from the in-focus position.
[0007]
In FIG. 14, S901 is a step for starting the execution of this control program, S902 is an execution of a program for moving the focus lens 101 in an arbitrary direction, and S903 is whether or not the focus voltage FV has decreased with the movement of the focus lens 101. S904 is a program for inverting the actuator for driving the focus lens 101, and S905 is a program for the focus lens 101 to reach the focal point in the course of steps S902 to S904. Execution of a program for determining the moving direction, S906: execution of a program for moving the focus lens 101 in the direction selected in step S905, and S907: execution of a program for determining whether the focus voltage FV has increased. S908 is a program for detecting that the change of the focus voltage FV is reduced or almost eliminated, S909 is a program for determining that the focus lens 101 has reached the focal point Pf, and stopping the movement of the focus lens 101; S910 is a step indicating that the execution of the program has been completed.
[0008]
When the execution of the program of the flowchart shown in FIG. 14 is started (S901), first, the focus lens 101 is moved in an arbitrary direction (S902). As a result of this movement, if it is determined in step S903 that the focus voltage FV has decreased (Yes), the focus lens 101 is moving in the opposite direction to the focal point Pf, so that the direction of the focus lens 101 is Is inverted (S904), and the focus voltage FV is checked again (S903). If the focus voltage FV has not decreased in the step S903 (No), the moving direction is determined as the direction in which the focus lens 101 approaches the focal point Pf (S905), and the focus lens 101 is moved (S906). .
[0009]
It is confirmed that the focus voltage FV increases while moving the focus lens 101 (S907). This state is the state of arrow 802 shown in FIG.
[0010]
Thereafter, when the focus lens 101 passes through the focal point Pf, the focus lens 101 once reaches a flat portion near the vertex of the curve 801 and it is determined in step S907 that the focus voltage FV has not increased (No). When the focus lens 101 continues to move, the focus voltage FV starts to decrease as indicated by the movement of the focus voltage FV indicated by an arrow 803 in FIG. This is detected (S903), and if a decrease is recognized (Yes), the actuator driving the focus lens 101 is inverted (S904). When the focus lens 101 reaches the apex of the above-described curve 801, the change in the focus voltage FV is detected to be small or no in step S908 (Yes). Then, the focus lens 101 is stopped (S909).
[0011]
As described above, the method described with reference to FIG. 14 is a basic method for performing AF using a video signal.
[0012]
[Problems to be solved by the invention]
However, in the above-described conventional example, the discrimination between in-focus and out-of-focus and the direction of the in-focus point Pf are performed only by the difference between the acquired one of the past focus voltages FV and the current focus voltage FV. The amount was small and there were the following disadvantages.
[0013]
(1) There is a high possibility that the driving direction of the focus lens 101 and the focus / non-focus decision are erroneously determined.
No.
[0014]
(2) In order to compensate for the disadvantage of (1) above, the number of accompanying programs is
Control becomes complicated.
[0015]
(3) It is difficult to predict a phenomenon related to AF, and the uncertainty in control is high.
[0016]
(4) Although the focus voltage FV shows a remarkable change on the way to focusing, the focus voltage FV does not change during both focusing and blurring. Even if the tendency is grasped, it cannot be determined whether the subject is in focus or out of focus. Therefore, the present invention has been made in view of the above circumstances, and is capable of determining whether the subject is in focus or a large blur, and which is capable of accurately and easily performing automatic focus adjustment. And automatic focus adjustment device The purpose is to provide.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, a camera according to claim 1 of the present invention includes a conversion unit that converts an optical image that has passed through an optical system including the focus adjustment lens into an electric signal while moving the focus adjustment lens, Sampling means for repeatedly sampling the high-frequency component value of the electric signal; and repeatedly sampling by the sampling means. The difference between adjacent high-frequency component values for multiple high-frequency component values Storage means for storing, and said storage means Written in Remembered Multiple said difference To Predetermined In addition to the block unit for each block, every Above difference Calculating means for taking a majority decision or an average for the number of positive and negative signs of, and said block in the block based on the calculation result of said calculating means difference Have almost the same number of positive and negative signs Also, when the absolute value of the high-frequency component value is smaller than a predetermined value, it is determined that the subject is not in focus and the focus adjustment operation is continued using the focusing lens, while the absolute value of the high-frequency component value is equal to the predetermined value. If it is larger, it is determined that the object is in focus, and the in-focus state is maintained using the focusing lens. And control means for controlling.
Further, in order to achieve the above object, the automatic focusing apparatus according to claim 3 of the present invention has Adjustment Sampling means for repeatedly sampling a focal voltage according to a focus state accompanying the movement of the lens, and repeatedly sampling by the sampling means. The difference between adjacent focus voltages for multiple focus voltages Storage means for storing, and the storage means stored in the storage means Multiple said difference To Predetermined In addition to the block unit for each block, every Above difference Calculating means for taking a majority decision or an average for the number of positive and negative signs of, and difference Have almost the same number of positive and negative signs Also, if the focus voltage is smaller than a predetermined value, it is determined that the camera is not in focus and the focus adjustment operation is continued using the focusing lens, while if the focus voltage is larger than a predetermined value, it is determined that the camera is in focus. Use a focusing lens to maintain focus And control means for controlling.
[0021]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0022]
FIG. 1 is a main part configuration diagram of a camera 100a according to a first embodiment of the present invention. This camera 100a has a focus lens 101, a zoom lens 102, a third lens group 103, a diaphragm 104, a fourth lens group 105 as focusing lenses similar to the conventional camera 10 shown in FIG. , A cam ring 107 for interlocking the zoom lens 102 and the third lens group 103, and actuators 108 and 109 as lens moving means for moving the focus lens 101, the cam ring 107, and the diaphragm 104, respectively. , 110, position encoders 111, 112, 113 for detecting the amount of movement of each of the focus lens 101, the cam ring 107, and the aperture 104, converting them into electric signals, and transmitting the signals to a system controller 300a described later, and actuators 108, 109. 114 and 11 for respectively driving the , An amplifier 116 for amplifying a video signal from the imaging surface 106, a well-known automatic iris adjustment unit 117, and a system controller described below that extracts only high-frequency components from the video signal from the imaging surface 106 output via the amplifier 116 The camera 100a has a high-pass filter 118 as a sampling unit for outputting to the camera 300a, and a system controller 300a for controlling each part of the camera 100a.
[0023]
The automatic aperture adjuster 117 automatically opens and closes the aperture 104 via the actuator 110 according to the signal level output from the imaging surface 106 via the amplifier 116.
[0024]
The system controller 300a includes a focus voltage absolute value memory 301, a focus voltage difference memory 302, a threshold value memory 303, a program memory 304a, and an arithmetic control unit 305a. The focus voltage absolute value memory 301, the focus voltage difference memory 302, and the threshold value memory 303 are configured by, for example, a RAM.
[0025]
As shown in FIG. 2, the focus voltage absolute value memory 301 stores data 201 of the absolute value Vo of the focus voltage in the last 20 consecutive vertical synchronization periods (20 Vsync). That is, when the signal of the absolute value Vo of the focal voltage is taken into the system controller 300a from the high-pass filter 118, the signal of the absolute value Vo is A / D-converted in the controller 300a under the control of the arithmetic control unit 305a. The data (absolute value Vo of the focus voltage) in the focus voltage absolute value memory 301 is shifted one by one in synchronization with the vertical synchronization signal, so that the latest data is stored. In FIG. 2, reference numeral 203 denotes an area where the focus lens 101 is approaching focusing on the subject by AF control by the system controller 300 a, and reference numeral 204 denotes that the focus lens 101 exists in the focusing area. Area.
[0026]
As shown in FIG. 2, the focus voltage difference memory 302 stores adjacent data Vo of the 20 absolute values Vo of the focus voltage values stored in the focus voltage absolute value memory 301, which are detected by the arithmetic control unit 305a. The data 202 of the voltage difference ΔFV obtained by taking the difference is stored.
[0027]
As shown in FIG. 9, the threshold memory 303 previously stores a threshold Vs of the focus voltage FV.
[0028]
The program memory 304a stores a program for executing steps S901 to S905 in FIG. 14, a program for executing the contents of a flowchart shown in FIG. 4 described later, and the like.
[0029]
The system controller 300a grasps optical conditions such as depth of field and sensitivity based on the position information from the position encoders 111, 112, and 113, and is suitable for the conditions such as increasing or decreasing the driving speed of the focus lens 101. AF control is performed, and focusing and out-of-focus are determined based on the data stored in the focus voltage absolute value memory 301 and the focus voltage difference memory 302. A drive command is transmitted from the system controller 300a to the actuator 108 via the driver 114 to move the focus lens 101 to execute focus adjustment. As shown in FIG. 3, the arithmetic and control unit 305a of the system controller 300a determines in-focus and out-of-focus based on the positive and negative patterns (1) to (4) of the data 202 of the voltage difference ΔFV. is there. When the focus voltage difference ΔFV is almost a positive value, for example, as in {circle around (1)}, the arithmetic control unit 305a determines that the focus lens 101 is presently in the area 203 where focus is being achieved. Also, as shown in (2), when the focus voltage difference ΔFV is almost a positive value and then becomes almost a negative value in the middle, the focal point Pf exists near the change point, It is determined that it has already passed. When the focus voltage difference ΔFV is almost a negative value as in (3), it is determined that the focus voltage difference ΔFV is moving in the direction opposite to the focusing. Further, as shown in (4), when the focus voltage difference ΔFV appears without a constant positive and negative value, the state is in focus or the state is so blurred that the focus voltage difference ΔFV does not appear at all ( It is determined that the focus lens 101 is present at the foot of the curve 801 in FIG. 9). The system controller 300a executes a scaling operation by a known method. That is, when the execution, stop, and scaling directions of the operation are selected by a scaling switch (not shown), the system controller 300a transmits a driving command to the actuator 109 via the driver 115. As a result, the cam ring 107 rotates, and the second and third lens groups 102 and 103 move in conjunction with each other, thereby performing a zooming operation.
[0030]
Next, AF control by the system controller 300a of the camera 100a according to the first embodiment having the above configuration will be described with reference to the flowchart of FIG.
[0031]
First, the arithmetic control unit 305a reads the program of steps S902 to S905 from the program memory 304a and executes it, as described in steps S902 to S905 of FIG. 14 (S901). The arithmetic control unit 305a sends a control signal to the actuator 108 via the driver 114, and moves the focus lens 101 in an arbitrary direction. Next, the arithmetic and control unit 305a determines whether the focus voltage FV has decreased (S903). The driving direction of the focus lens 101 is determined (S905). As the focus lens 101 continues to move in this direction, the focus voltage FV gradually increases. This state is shown in a portion corresponding to the area 203 of the data 201 as shown in FIG. Therefore, the focus voltage difference ΔFV shown in the data 202 also has a positive value in the area corresponding to the area 203. When the focus lens 101 continues to be driven in the same direction, the subject image projected on the imaging surface 106 enters a focus area 204 that is considered to be in focus. As is well known, the area where the focus lens 101 is considered to be in focus changes depending on the focus sensitivity and the depth of field. Are also determined to be in focus. Therefore, in the focusing area 204, the data 201 of the absolute value Vo of the focus voltage hardly changes, and the value of the data 202 of the difference ΔFV also has a small absolute value, as shown in FIG. The state shown by the pattern (4) is reached. Further, as is clear from FIG. 9, in the region where the region 203 changes to the region 204, the rate of increase of the focus voltage FV decreases, so that the absolute value of the focus voltage difference ΔFV also gradually decreases.
[0032]
Next, the case where the state of (4) in FIG. 3 is set will be described. The arithmetic control unit 305a reads out the program of the flowchart shown in FIG. 4 from the program memory 304a and executes it (S401). The arithmetic and control unit 305a of the system controller 300a determines whether the current focus state is the state of (4) in FIG. 3 (S402). If it is determined that the state is not the state of (4) (No), the focus adjustment is continued (S405). When the arithmetic control unit 305a determines in the step S402 that the state is {circle around (4)} (Yes), the absolute value Vo of the focus voltage or the stored value of the vertical synchronization period at that time is set to the threshold Vs stored in the threshold memory 303 in advance. It is determined whether or not it has exceeded (S403). Since the state of (4) is either the vertex (focus) or the foot (large blur) in the curve of FIG. 9, it is easy to classify this in comparison with the threshold value Vs. When the arithmetic control unit 305a determines that the absolute value Vo of the focus voltage input in step S403 is larger than the threshold value Vs (Yes), it regards this as in-focus and stops the focus lens 101 (S404). If it is determined in step S403 that the value is smaller than the threshold value Vs (No), the focus adjustment operation is continuously performed (S405).
[0033]
According to the camera 100a of the first embodiment configured as described above, the driving direction of the focus lens 101, the in-focus state, and the out-of-focus state are determined by the positive and negative patterns (1) to (4) of the data 202 of the focus voltage difference ΔFV. Since focus determination is performed, focus adjustment can be performed without erroneous state.
[0034]
Further, since the absolute values Vo and the difference ΔFV of a plurality of past focus voltages, which are relatively large amounts of information, are stored, it is possible to easily infer the state of the focus voltage FV by observing the change. As a result, there are few errors in the result, and even if an error is made, it is easier to correct the error by using past information as compared with the related art.
[0035]
Further, by making an inference as shown in FIG. 3, it becomes easier to make predictions for phenomena that will occur in the future. Further, according to this method, since the absolute value Vo of the focus voltage is not directly used for the AF control, for example, even if the focus voltage FV suddenly drops as shown in FIG. Since this is ignored and only the slope of the increase of the focus voltage FV is tracked, a malfunction as seen so far is unlikely to occur.
[0036]
Further, by performing the above processing, even if the content of the data 202 of the focal voltage difference ΔFV is in the state of (4) in FIG. Can be performed. Therefore, the number of accompanying programs is small, and the overall control can be simplified.
[0037]
FIG. 5 is a schematic configuration diagram of a system controller 300b of the camera 100b according to the second embodiment of the present invention. The camera 100b of the second embodiment has the same configuration as the camera 100a of the first embodiment shown in FIG. 1 except for the system controller 300b. A system controller 300b shown in FIG. 5 includes a focus voltage absolute value memory 301, a focus voltage difference memory 302, and a threshold memory 303 similar to those of the camera 100a of the first embodiment, a program memory 304b, and an arithmetic control unit 305b. Have.
[0038]
The program memory 304b stores a program and the like for executing the AF control by the arithmetic control unit 305b.
[0039]
As shown in FIG. 6, the arithmetic control unit 305b calculates the absolute value Vo of the focus voltage corresponding to the area 203 approaching the focus. Adjacent difference The data 201 is divided into several blocks, and for each block, a majority decision or an average is performed on the number of positive and negative signs of the voltage difference ΔFV of the absolute value Vo. Number of Is large enough, the entire block 501 is treated as positive. If almost the same number of each code exists as in the block 504, it is determined that the state is the pattern (4) shown in FIG.
[0040]
According to the camera 100b of the second embodiment configured as described above, the following effects can be obtained. For example, due to noise or a sudden change in the subject, a sign indicating a decrease in some places may appear in the region 203 toward focusing even in a portion where the focal length is continuously increasing. Conversely, a positive sign indicating an increase may appear in a part that tends to decrease. These phenomena give the possibility of erroneously recognizing focusing or blurring even during focusing, and are not preferred by the AF control function. However, by performing the processing described above, even if there is noise or a sudden change in the subject during focusing, good AF can be performed without being directly affected by this.
[0041]
FIG. 7 is a schematic configuration diagram of a system controller 300c of the camera 100c according to the third embodiment of the present invention. The camera 100c of the third embodiment has the same configuration as the camera 100a of the first embodiment shown in FIG. 1 except for the system controller 300c. A system controller 300c illustrated in FIG. 7 includes a focus voltage absolute value memory 301, a focus voltage difference memory 302, and a threshold memory 303 similar to those of the camera 100a of the first embodiment, a program memory 304c, an arithmetic control unit 305c, and the like. , A calculation method memory 306.
[0042]
In the calculation method memory 306, a calculation method F1 for subtracting a coefficient K for weighting from ΔFVn−1 as ΔFVn, a calculation method F2 for substituting −1 as ΔFVn, and a calculation method for substituting +1 as ΔFVn A method F3 and a calculation formula F4 for adding a coefficient K for weighting ΔFVn−1 as ΔFVn are stored in advance.
[0043]
The program memory 304c stores a program for executing the contents of a flowchart shown in FIG.
[0044]
The calculation control unit 305c performs various calculations in the flowchart shown in FIG. That is, the arithmetic and control unit 305c calculates the sign of ΔFVn, which is the difference between the current focus voltage FV and the immediately preceding focus voltage FV, and the sign of the difference ΔFVn−1 between the immediately preceding focal distance and the difference ΔFVn−1. Various calculations (S605 to S607) are performed.
[0045]
Next, AF control by the system controller 300c of the camera 100c according to the third embodiment having the above configuration will be described with reference to the flowchart shown in FIG.
[0046]
When the execution of the program is started (S601), the arithmetic control unit 305c calculates ΔFVn (S602). Next, the arithmetic and control unit 305c performs a positive / negative determination of ΔFVn (S603) and a positive / negative determination of a difference ΔFVn−1 of the focus voltage V (S604, S605), and selects a calculation method of ΔFVn based on the positive / negative result. (S607 to S610).
[0047]
If the value is negative twice in succession, the arithmetic control unit 305c reads the calculation method F1 from the calculation method memory 306, calculates the value, and inputs the value as ΔFVn to the calculation memory 306 (S607). If it becomes positive next to negative, the calculation method F2 is read from the calculation method memory 306 and calculated, and the value is input to the calculation memory 306 as ΔFVn (S608). Similarly, when it becomes positive and then negative, the value calculated by the calculation method F3 is input to the calculation memory 306 as ΔFVn (S609). If the value becomes positive two consecutive times, the value calculated by the calculation method F4 is input to the calculation memory 306 as ΔFVn (S610), and the execution of the program is terminated (S611).
[0048]
As is clear from FIG. 8, if the same code continues three times, the weighted numerical value becomes larger.
[0049]
According to the camera 100c of the third embodiment configured as described above, the above-described processing is performed on the sign of the difference between the focal voltages V, and then the average value as described in the embodiment shown in FIG. If the calculation and the block division are performed, for example, even if the focus voltage FV is increasing as a whole, some decreasing tendency appears, the increasing weight has priority over the decreasing voltage, which is an error factor. Is ignored. As shown in FIG. 10, a state in which a high-luminance subject 1003 and a person 1004 are included in a distance measurement frame 1002 in a photographing screen 1001 (photographing on a relatively wide side), only a person 1004 as shown in FIG. When the zooming operation is performed in a state where the zoom lens is within the distance measuring frame 1002 (photographing on the relatively telephoto side), the focus voltage FV drops rapidly as shown in FIG. Even if such a phenomenon occurs, accurate AF control can be continued without disrupting the processing.
[0050]
In the case where the numbers of the positive and negative signs are similar as in the block 502 and the block 504 in FIG. 6, it is easy to determine that the focus is achieved in the second embodiment, but in the third embodiment, the focus is continuously determined. Since the determination is made by changing the weight between the case where the same code appears and the case where the same code does not appear, it is possible to more accurately determine whether the object is in focus or out of focus.
[0051]
The present invention is not limited to the above-described embodiment, and can be variously modified without departing from the scope of the invention.
[0052]
【The invention's effect】
According to the present invention as described above, it is also possible to determine whether the subject is in focus or a large blur, Auto focus Accurate and easy Can do Possible Becomes .
[Brief description of the drawings]
FIG. 1 is a main part configuration diagram of a camera according to a first embodiment of the present invention.
FIG. 2 is a diagram showing the operation of the camera shown in FIG.
FIG. 3 is a diagram showing an operation of the camera shown in FIG.
FIG. 4 is a flowchart showing the operation of the camera shown in FIG.
FIG. 5 is a schematic configuration diagram of a system controller of a camera according to a second embodiment of the present invention.
FIG. 6 is a diagram showing the operation of the camera shown in FIG.
FIG. 7 is a schematic configuration diagram of a system controller of a camera according to a third embodiment of the present invention.
FIG. 8 is a flowchart showing the operation of the system controller shown in FIG. 7;
FIG. 9 is a change curve diagram of a focal voltage.
FIG. 10 is a diagram illustrating an example of a shooting screen.
FIG. 11 is a diagram illustrating an example of a shooting screen.
FIG. 12 is a diagram showing an example in which a focal voltage has dropped sharply.
FIG. 13 is a diagram showing an optical system of a conventional camera.
FIG. 14 is a flowchart showing the operation of a conventional camera.
[Explanation of symbols]
100a camera
101 Focus lens (focus adjustment lens)
106 imaging surface (conversion means)
108 Actuator (lens moving means)
118 high-pass filter (sampling means)
301 Focus voltage absolute value memory (high frequency component value storage means)
302 Focus voltage difference memory
305a arithmetic control unit (control means)
FV Focus voltage
ΔFV Focal voltage difference

Claims (3)

A conversion unit that converts an optical image that has passed through an optical system including the focus adjustment lens into an electric signal while moving the focus adjustment lens,
Sampling means for repeatedly sampling the high-frequency component value of the electric signal,
For a plurality of high frequency component values obtained by repeatedly sampling by the sampling means, storage means for storing a plurality of differences between adjacent high frequency component values ,
Calculating means for taking a majority vote or average for the number of positive or negative sign of the difference for each said block with the said storage means remembers the block unit plurality of said differences into a predetermined plurality of each,
Even if the number of positive and negative signs of the difference in the block is substantially the same based on the calculation result of the calculation means, if the absolute value of the high-frequency component value is smaller than a predetermined value, it is determined that the object is not in focus. The focus adjustment operation is continued by using the focus adjustment lens, while if the absolute value of the high frequency component value is larger than a predetermined value, it is determined to be in focus and the focus is maintained by using the focus adjustment lens. And a control means for performing such control. Wherein the storage unit, according to claim 1, wherein the camera which is characterized by being configured to store a signal of the difference between the absolute value of the high frequency component values. Sampling means for repeatedly sampling a focus voltage according to a focus state accompanying movement of the focus adjustment lens,
For a plurality of focus voltages obtained by repeatedly sampling by the sampling means, storage means for storing a plurality of differences between adjacent focus voltages ,
Arithmetic means for taking a majority or an average of the number of positive and negative signs of the difference for each block, with the plurality of differences stored in the storage means being in units of blocks for each predetermined plurality,
Even if the numbers of the positive and negative signs of the difference in the block are substantially the same based on the calculation result of the calculation means, if the focus voltage is smaller than a predetermined value, it is determined that the lens is not in focus and the focus lens is used. Control means for controlling the focus adjustment operation to be continued while the focus voltage is larger than a predetermined value, and controlling to maintain the focus state using the focus adjustment lens when the focus voltage is larger than a predetermined value. Automatic focusing device.

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