JP7023673B2 - Focus control device, focus control method, and image pickup device - Google Patents

Description

The present invention relates to a focus adjustment technique for performing focus detection by a phase difference detection method.

Some image pickup devices such as digital cameras employ an imaging surface phase difference detection method that performs focus detection by a phase difference detection method using an output signal from an image pickup element for capturing a subject image. In the phase difference detection method including the imaging surface phase difference detection method, when the subject image has a periodic pattern, a plurality of positions of focus lenses (hereinafter referred to as focus candidate positions) that are candidates for obtaining an in-focus state are detected. May occur.

In this case, it is difficult in principle with the phase difference detection method to specify one in-focus position from which a true in-focus state can be obtained from a plurality of in-focus candidate positions. Therefore, when a false focus that is determined to be erroneously focused occurs at a lens position that is not one focus position where a true focus state can be obtained, and an image that is out of focus is generated. Exists.

Patent Document 1 discloses an image pickup device that identifies a true in-focus position when a subject image has a periodic pattern. That is, the defocus amount (focus detection information) up to a plurality of in-focus candidate positions is calculated, and the focus lens is driven to each in-focus candidate position based on these defocus amounts to acquire an evaluation value. Then, the focusing candidate position from which the highest evaluation value is obtained is specified as the true focusing position.

Japanese Unexamined Patent Publication No. 2015-055653

However, in the method disclosed in Patent Document 1, for example, as shown in FIG. 11, when the subject image has a periodic pattern, the focus candidate position is not near the true focus position (large blur). But the amount of defocus is calculated.

The defocus amount calculated at this time has low reliability (accuracy), and if the focus lens is driven based on this, the focus lens may move to a position different from the in-focus candidate position. Then, even if the in-focus position is specified using the evaluation value acquired at the position of the focus lens different from the in-focus candidate position, there is a possibility that the true in-focus position cannot be specified with high accuracy.

It is also possible to repeat the calculation of the defocus amount and the driving of the focus lens in order to increase the reliability of the defocus amount. However, it takes time to identify the true focusing position, or the focus lens moves in different directions a plurality of times, so that the responsiveness and quality of the focus control deteriorate.

Therefore, an object of the present invention is to provide a focus adjustment technique capable of focusing at a true focusing position without causing blurring due to false focusing even when a plurality of focusing candidate positions exist. do.

In order to achieve the above object, the focus adjustment device of the present invention includes an acquisition means for acquiring a pair of phase difference image signals having a phase difference according to the focus detection result of the subject image from the output signal of the image pickup element, and the above-mentioned. A generation means for generating a defocus amount that controls the position of a focus lens using a standard region in a pair of phase difference image signals and a narrow region narrower than the standard region, and reliability regarding the reliability of the defocus amount . A combination of an evaluation value determining means for determining an evaluation value by comparison with a plurality of levels divided by a plurality of thresholds, a threshold setting means for setting the plurality of thresholds, and a phase difference image signal of the pair. The candidate determination means for determining whether or not there are a plurality of candidates for the position of the focus lens from which the focused state can be obtained, and the defocus amount in the standard region when the candidate determination means determines that there are a plurality of the candidates. When it is determined that the false focus determination means for determining whether or not the position of the focus lens is in false focus and the false focus determination means are the positions of the focus lens in false focus. It is characterized by comprising a control means for lowering the level of the reliability evaluation value of the defocus amount corresponding to the position of the focus lens determined to be false focus .

According to the present invention, in AF control using a phase difference detection method or an imaging surface phase difference detection method, it is possible to prevent defocusing in a repetitive subject and realize highly accurate and suitable focusing.

It is a block diagram which shows the structure of the digital camera which is an example of embodiment of the image pickup apparatus provided with the focus adjustment apparatus of this invention. It is a figure explaining the pixel composition of the image pickup surface phase difference system. It is a flowchart explaining the shooting process. It is a flowchart explaining the automatic focus detection process in step S302 of FIG. It is a graph which illustrates the amount of the correlation change when the focus lens is driven from the state where the degree of blurring is large to the vicinity of the in-focus point in the image pickup surface phase difference AF. It is a flowchart explaining the calculation example of the threshold value of a standard deviation. It is a graph which shows the relationship between Def3σTH2 and the amplitude PB. It is a flowchart explaining the selection process of the defocus amount. It is a graph which illustrates the correlation waveform of the standard region corresponding to the case where there is a focus lens in the vicinity of a false focus position. It is a flowchart explaining the reverse mountain determination. It is a graph which explains the pair phase difference image signal at the time of the reverse mountain determination in a repetitive subject.

Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a digital camera which is an example of an embodiment of an image pickup apparatus including the focus adjustment device of the present invention.

In the digital camera of the present embodiment, as shown in FIG. 1, an interchangeable lens unit 10 is detachably attached to the front side of the camera body 20.

The lens unit 10 includes a fixed lens (group 1 lens) 101, an aperture 102, a focus lens 103, an aperture drive unit 104, a focus lens drive unit 105, a lens control unit 106, and a lens operation unit 107. The fixed lens 101, the aperture 102, and the focus lens 103 constitute a photographing optical system.

The diaphragm 102 is driven by the diaphragm driving unit 104 and controls the amount of light incident on the image pickup device 201, which will be described later. The focus lens 103 is driven by the focus lens driving unit 105, and adjusts the focus formed on the image pickup device 201, which will be described later. The aperture drive unit 104 and the focus lens drive unit 105 are controlled by the lens control unit 106 to determine the aperture amount of the aperture 102 and the position of the focus lens 103.

When there is a user operation by the lens operation unit 107, the lens control unit 106 performs control according to the user operation. The lens control unit 106 controls the entire lens unit 10. The lens control unit 106 controls the aperture drive unit 104 and the focus lens drive unit 105 in response to control commands and control information received from the camera control unit 212, which will be described later, and transfers the lens control information to the camera control unit 212. Send.

Next, the camera body 20 will be described. The camera body 20 is configured to be able to acquire an image pickup signal from a light flux that has passed through the photographing optical system of the lens unit 10. The camera body 20 includes a bus 21, an image sensor 201, a CDS / AGC / AD converter 202, an image input controller 203, an AF signal processing unit 204, a display control unit 205, a display unit 206, a recording medium control unit 207, and a recording medium 208. To prepare for. Further, the camera body 20 includes a DRAM 209, a ROM 210, a flash ROM 211, a camera operation unit 214, and a camera control unit 212, and the camera control unit 212 includes an AF control unit 213.

The image pickup element 201 is composed of a CCD sensor and a CMOS sensor, forms an image of a light flux passing through the photographing optical system of the lens unit 10 on the image pickup surface, and converts it into a signal charge according to the amount of incident light by a photodiode. The signal charge accumulated in each photodiode is sequentially read out from the image sensor 201 as a voltage signal corresponding to the signal charge based on the drive pulse given from the timing generator 215 according to the command of the camera control unit 212.

FIG. 2 is a diagram illustrating a pixel configuration of the imaging surface phase difference method. As shown in FIG. 2, the image pickup device 201 holds two photodiodes in one pixel in order to perform image pickup surface phase difference AF. By separating the luminous flux with a microlens and forming an image with these two photodiodes, two signals for imaging and AF can be taken out. The signal (A + B) obtained by adding the signals of the two photodiodes is the imaging signal, and the signals (A and B) of the individual photodiodes are the two image signals for AF. Based on the AF signal, the AF signal processing unit 204 performs a correlation calculation on the two image signals to calculate the amount of image shift and various reliability information.

The image pickup signal and AF signal read from the image pickup element 201 are input to the CDS / AGC / AD converter 202, and perform correlated double sampling for removing reset noise, gain adjustment, and signal digitization. The CDS / AGC / AD converter 202 outputs an image pickup signal to the image input controller 203, and outputs a signal for image pickup surface phase difference AF to the AF signal processing unit 204.

The image input controller 203 stores the image pickup signal output from the CDS / AGC / AD converter 202 in the SDRAM 209. The image signal stored in the SDRAM 209 is displayed on the display unit 206 by the display control unit 205 via the bus 21. Further, in the mode of recording the image pickup signal, the recording medium control unit 207 records the image on the recording medium 208. Further, the ROM 210 connected via the bus 21 stores the control program executed by the camera control unit 212 and various data necessary for control, and the flash ROM 211 stores the operation of the camera body 20 such as user setting information. Various setting information related to is stored.

The AF signal processing unit 204 performs a correlation calculation based on the two image signals for AF output from the CDS / AGC / AD converter 202, and performs an image shift amount and reliability information (two-image matching degree, contrast information, etc.). Calculate saturation information, scratch information, etc.). Then, the AF signal processing unit 204 outputs the calculated image shift amount and reliability information to the camera control unit 212.

The camera control unit 212 notifies the AF signal processing unit 204 of a change in the setting for calculating these based on the acquired image shift amount and reliability information. For example, when the amount of image shift is large, the area for performing the correlation calculation is set wide, or the type of the bandpass filter is changed according to the contrast information.

In this embodiment, a total of three signals, an image pickup signal and two AF image signals, are acquired from the image pickup element 201, but the present embodiment is not limited to this. Considering the load of the image sensor 201, for example, a total of two images, an image pickup signal and one AF image signal, are taken out, and the difference between the image pickup signal and the AF signal is taken to generate another AF image signal. It may be controlled.

The camera control unit 212 controls the entire camera body 20. The camera control unit 212 not only processes the camera body 20, but also turns the power on / off, changes settings, starts recording, starts AF control, confirms the recorded image, etc. according to the input from the camera operation unit 214. Performs various camera functions operated by the user. Further, the camera control unit 212 exchanges information with the lens control unit 106 of the lens unit 10, sends control commands and control information of the lens unit 10, and acquires information of the lens unit 10. The AF control unit 213 in the camera control unit 212 controls focusing on the subject.

Next, the photographing process will be described with reference to FIG. FIG. 3 is a flowchart illustrating a shooting process. Each process of FIG. 3 is executed by the CPU of the camera control unit 212 or the like by expanding the program stored in the storage unit such as the ROM 210 into the RAM.

In FIG. 3, in step S301, the camera control unit 212 determines whether or not the release switch (SW1) is turned on by half-pressing the release button (not shown), and if it is on, step S302. move on.

In step S302, the camera control unit 212 performs automatic focus detection processing by the AF control unit 213, and proceeds to step S303. The automatic focus detection process here will be described later with reference to FIG.

In step S303, the camera control unit 212 acquires the focus detection information, determines whether or not the focus detection result calculated in step S302 is in the in-focus range, and if it is in the in-focus range, goes to step S305. If it is not in the focusing range, the process proceeds to step S304.

In step S304, the camera control unit 212 transmits a drive command for the focus lens 103 to the focus lens drive unit 105 via the lens control unit 106, and returns to step S302. As a result, the drive control of the focus lens 103 is performed based on the focus detection result calculated in step S302.

In step S305, the camera control unit 212 determines whether or not the release switch (SW2) is turned on by fully pressing the release button (not shown), and if it is on, proceeds to step S306 and turns it on. If not, the process proceeds to step S307.

In step S307, the camera control unit 212 determines whether or not the release switch (SW1) is turned on by half-pressing the release button (not shown), and if it is on, returns to step S305 and must be turned on. If so, the process ends.

In step S306, the camera control unit 212 performs a shooting operation and proceeds to step S308. In step S308, the camera control unit 212 records the captured image data on the recording medium 208, and ends the process.

Next, with reference to FIG. 4, the automatic focus detection process in step S302 of FIG. 3 will be described.

In FIG. 4, in step S401, the camera control unit 212 causes the AF signal processing unit 204 to perform a correlation operation on the pair of phase difference image signals acquired from the image pickup device 201 by the AF control unit 213. Then, the AF control unit 213 calculates the defocus amount based on the image shift amount, which is the shift amount Shift in which the correlation amount received from the AF signal processing unit 204 is the minimum value. At this time, the correlation operation is performed in the standard region (Middle) in which the used region of the pair of phase difference image signals is widened and the narrow region (Narrow) in which the used region is narrowed.

In Middle, correlation calculation is performed using three types of filters with different frequency bands, one for low frequency, one for mid frequency, and one for high frequency, and three types of defocus amount for low frequency, mid frequency, and high frequency are obtained. calculate. In Narrow, correlation calculation is performed using two types of filters with different frequency bands, one for mid-range and one for high-range, and two types of defocus amount for mid-range and high-range are calculated.

Further, the camera control unit 212 calculates the correlation amount of the phase difference image signal of the pair to the AF signal processing unit 204 by the AF control unit 213 for each shift amount Shift, and for each shift amount Shift received from the AF signal processing unit 204. A waveform of the correlation amount of is generated, and the process proceeds to step S402.

In step S402, the camera control unit 212 calculates the amount of correlation change between the two images by the AF control unit 213.

FIG. 5 is a graph illustrating the amount of correlation change when the focus lens 103 is driven from a state in which the degree of blurring is large to the vicinity of the in-focus point in the imaging surface phase difference AF. In FIG. 5, the horizontal axis represents the degree of blurring of the subject, and the vertical axis represents the correlation change amount MAXDER. The correlation change amount MAXDER can be calculated by the following equation (1).

MAXDER (k) = (COR [k-3] -COR [k-1])-(COR [k-2] -COR [k]) ... (1)
In the above equation (1), k is an integer variable for specifying the position, and COR [k] is the correlation amount of the two images at the position k. At this time, the camera control unit 212 calculates three types of correlation change amounts MAXDER for low frequencies, mid frequencies, and high frequencies with different filter frequency bands by the AF control unit 213, as in step S401. The process proceeds to step S403. As shown in FIG. 5, in the imaging surface phase-difference AF, it can be seen that the value of the correlation change amount MAXDER becomes relatively large as the degree of blurring approaches the vicinity of the in-focus position.

In step S403, the camera control unit 212 calculates the standard deviation Defocus3σ of the defocus amount based on the correlation change amount MAXDER by the AF control unit 213, and proceeds to step S404. The standard deviation Defocus3σ of the defocus amount can be calculated by using the following equation (2).

Defocus3σ = K × (A × MAXDER ^ B)… (2)
K in the above equation (2) is a conversion coefficient for converting the image shift amount into a defocus amount, and A and B are coefficients of the conversion equation for converting the correlation change amount MAXDER to the standard deviation of the image shift amount. At this time, by substituting the three types of correlation change amount MAXDER for low frequency, mid frequency, and high frequency with different frequency bands calculated in step S402, the standard deviation Defocus3σ of the three types of defocus amount is calculated. do.

In step S404, the camera control unit 212 calculates the threshold value of the standard deviation Defocus3σ of the calculated defocus amount in order to calculate the reliability evaluation value Rel representing the reliability of the defocus amount by the AF control unit 213. , Step S405. The reliability evaluation value Rel is determined in four stages of reliability evaluation value Rel3, reliability evaluation value Rel2, reliability evaluation value Rel1, and reliability evaluation value Rel0 in descending order of reliability.

Here, when the reliability evaluation value Rel is the reliability evaluation value Rel 3, the defocus amount is highly reliable, so the condition is such that focusing is possible. When the reliability evaluation value Rel is the reliability evaluation value Rel2, the defocus amount for the past m frames and the defocus amount calculated for the current frame are added and averaged, and when the result is equal to or less than the predetermined value. It is a condition that can be burnt.

Further, the reliability evaluation value Rel1 means that the directions of the calculated defocus amount are correct, and the reliability evaluation value Rel0 means that the reliability as the defocus amount is the lowest. The condition is that it cannot be burnt. When the reliability evaluation value Rel1 and the reliability evaluation value Rel0 are set, the search drive for driving the focus lens 103 by a certain amount is performed without using the calculated defocus amount.

When the standard deviation Defocus3σ of the calculated defocus amount exceeds the standard deviation threshold Def3σTH1, Rel0 is selected. Further, when the standard deviation Defocus3σ of the calculated defocus amount exceeds the standard deviation threshold Def3σTH2 and is equal to or less than the standard deviation threshold Def3σTH1, Rel1 is selected. Then, when the standard deviation Defocus3σ of the calculated defocus amount exceeds the standard deviation threshold Def3σTH3 and is equal to or less than the standard deviation threshold Def3σTH2, Rel2 is selected, and in other cases, Rel3 is selected.

Here, an example of calculating the threshold value of the standard deviation Defocus3σ will be described with reference to FIG. In FIG. 6, in step S601, the camera control unit 212 calculates the standard deviation threshold Def3σTH1 by the AF control unit 213, and proceeds to step S602. Def3σTH1 sets a predetermined value. In step S602, the camera control unit 212 calculates the standard deviation threshold Def3σTH2 by the AF control unit 213, and proceeds to step S603. Def3σTH2 is set to a value smaller than Def3σTH1.

In step S603, the camera control unit 212 determines whether or not the AF control unit 213 calculates the standard deviation threshold value for the defocus amount for the mid range, and determines whether the aperture value F is equal to or greater than the predetermined value F_TH. do. Then, if the standard deviation threshold value for the defocus amount for the mid range is calculated and the aperture value F is equal to or larger than the predetermined value F_TH, the process proceeds to step S604, and if not, the process proceeds to step S605.

In step S604, the camera control unit 212 makes Def3σTH2 variable based on the amplitude PB, which is the difference between the maximum value and the minimum value of the image signal, by the AF control unit 213, and proceeds to step S605. FIG. 7 is a graph showing the relationship between Def3σTH2 and the amplitude PB. The amplitude PB is a value that changes according to the subject brightness, and when the value is small, the subject brightness is low. Therefore, when the amplitude PB is small, the reliability evaluation value Rel can be increased by increasing Def3σTH2.

In step S605, the camera control unit 212 calculates the standard deviation threshold Def3σTH3 by the AF control unit 213, and ends the process. Def3σTH3 is set to a value smaller than Def3σTH2. By doing so, it is possible to increase the in-focus ratio when shooting a low-brightness subject with a small aperture.

Returning to FIG. 4, in step S405, the camera control unit 212 calculates the reliability evaluation value Rel indicating the reliability of the calculated defocus amount by the AF control unit 213 (evaluation value calculation), and in step S406. move on. Here, based on the Def3σTH1, Def3σTH2, and Def3σTH3 calculated in step S404, the reliability evaluation value for the frequency band defocus amount of each filter calculated in step S401 is calculated in each signal region of Middle and Narrow.

In step S406, the camera control unit 212 selects the defocus amount calculated in step S401 by the AF control unit 213. Here, when the AF frame (distance measuring frame) is set to the small frame / magnified mode, it is based on the two types of defocus amount for the mid range and the high range and the reliability calculated in step S405. Select one defocus amount for. The defocus amount calculated by a plurality of filters, for example, a filter for a mid range is defined as a medium Def, and the defocus amount calculated by a filter for a high range is defined as a small Def.

Here, an example of the defocus amount selection process will be described with reference to FIG. In FIG. 8, in step S801, the camera control unit 212 determines the takeover from the medium Def to the small Def by the AF control unit 213, and proceeds to step S802. The determination here is made based on the difference in the defocus amount between the medium Def and the small Def and the reliability evaluation value Rel for each defocus amount.

In step S802, the camera control unit 212 uses the AF control unit 213 to check whether or not the medium Def has been handed over to the small Def, and if the camera has been handed over, the process proceeds to step S803. ..

In step S803, the camera control unit 212 selects a small Def as the defocus amount to be used by the AF control unit 213, ends the process, and proceeds to step S407 of FIG. In step S804, the camera control unit 212 selects the medium Def as the defocus amount to be used by the AF control unit 213, ends the process, and proceeds to step S407 of FIG.

Returning to FIG. 4, in step S407, the camera control unit 212 determines that the reverse peaks in the pair of phase difference image signals as shown in FIG. 11 overlap (blurring) in the repeated subject. I do. FIG. 9 exemplifies the correlation waveform of the standard region (Middle) corresponding to the case where the focus lens 103 is located near the false in-focus position shown in FIG. 11, the horizontal axis represents the shift amount Shift, and the vertical axis represents the shift amount Shift. Represents the correlation amount COR.

The shift amount Shift indicates that the larger the value, the larger the deviation between the waveforms of the two images and the larger the blurring of the subject image. Further, the smaller the correlation amount COR is, the better the degree of matching of the waveforms of the two images used in the focus detection operation output from the AF sensor is. At the time of focus detection, the shift amount Shift that becomes the in-focus point is calculated from the portion where the correlation amount COR becomes the minimum. In order to prevent a blurred image from being generated due to focusing at a false focusing position as shown in FIG. 9, a reverse mountain determination is performed by Middle.

Here, the reverse mountain determination (false focusing determination) will be described with reference to FIG. 10. In FIG. 10, in step S1001, the camera control unit 212 performs candidate determination by the AF control unit 213 to check whether or not there are two (plural) minimum values of the correlation amount COR in the Def in the Middle. Then, if there are two minimum values of the correlation amount COR in Middle, the process proceeds to step S1002, and if the two do not exist, the process proceeds to step S1005. In this embodiment, the correlation amount COR of medium Def is used, but the correlation amount COR of large Def or small Def may be used.

In step S1002, the camera control unit 212 calculates the sharpness evaluation value Sharpness / PB in order to evaluate the sharpness of the subject by the AF control unit 213. The sharpness of the image Sharpness can be calculated by using the following equation (3).

Sharpness = Σ (S [k + 1] -S [k]) ² / Σ (S [k + 1] -S [k]) ... (3)
However, k is an integer variable for specifying the position, and S [k] is the signal value of the phase difference image signal at the position k. The sharpness evaluation value Sharpness / PB is calculated using the sharpness Sharpness of the image calculated from the above equation (3), and if the Sharpness / PB is equal to or less than the predetermined value, the process proceeds to step S1003, and if the sharpness exceeds the predetermined value , Step S1005.

In step S1003, the camera control unit 212 calculates, by the AF control unit 213, the correlation change integral amount MAXDER_EX obtained by integrating the correlation change amount MAXDER from the maximum value to the minimum value at the minimum value of the correlation amount COR. Then, it is determined whether or not the value (Min / Max) obtained by dividing the calculated value by the smaller Min to the larger Max is equal to or less than the predetermined value, and if the value (Min / Max) is equal to or less than the predetermined value, the step is performed. The process proceeds to S1006, and if the value exceeds a predetermined value, the process proceeds to step S1004.

In step S1004, the camera control unit 212 calculates the image match degree FNCLVL by the AF control unit 213 at the minimum value of the correlation amount COR to represent the match degree of the waveforms of the two images. Then, it is determined whether or not the value (Min / Max) obtained by dividing the calculated value by the smaller Min to the larger Max is equal to or less than the predetermined value, and if the value (Min / Max) is equal to or less than the predetermined value, the step. The process proceeds to S1006, and if the value exceeds a predetermined value, the process proceeds to step S1005.

In step S1005, the camera control unit 212 determines that the reverse mountain determination is false by the AF control unit 213, ends the process, and proceeds to step S408 of FIG. In step S1006, the camera control unit 212 determines that the reverse mountain determination is true by the AF control unit 213, ends the process, and proceeds to step S408 of FIG.

Returning to FIG. 4, in step S408, in step S408, the AF control unit 213 determines that the Middle reverse mountain determination in step S407 is true, and the reliability evaluation value Rel calculated in step S405 is Rel2. It is determined whether or not the value is equal to or greater than the predetermined value. If the Middle reverse mountain determination in step S407 is true and the reliability evaluation value Rel calculated in step S405 is Rel2 or more, the process proceeds to step S409. If not, the determination is false. If there is, the process ends.

In step S409, the camera control unit 212 lowers the reliability evaluation value Rel calculated in step S405 to Rel1 by the AF control unit 213, and ends the process. By doing so, the focus lens 103 can be search-driven so that the focus lens 103 can pass through without stopping at the position where the out-of-focus focus occurs. Therefore, it is possible to focus at the true focusing position. As a result, it is possible to prevent the harmful effect of focusing the image while it is out of focus, and to increase the number of shooting scenes that can be focused accurately.

As described above, in the present embodiment, in AF control using a phase difference detection method or an imaging surface phase difference detection method, it is possible to prevent defocusing in a repetitive subject and realize highly accurate and suitable focusing. can.

The present invention is not limited to those exemplified in the above embodiments, and can be appropriately modified without departing from the gist of the present invention.

The present invention is also realized by executing the following processing. That is, the present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads the program. It can also be realized by the processing to be executed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

10 Lens unit 20 Camera body 103 Focus lens 105 Focus lens drive unit 106 Lens control unit 204 AF signal processing unit 210 ROM
212 Camera control unit 213 AF control unit

Claims (8)

An acquisition means for acquiring a pair of phase difference image signals having a phase difference according to the focus detection result of the subject image from the output signal of the image sensor, and
A generation means for generating a defocus amount for controlling the position of the focus lens by using a standard region in the pair of phase difference image signals and a narrow region narrower than the standard region .
An evaluation value determining means for determining the reliability evaluation value regarding the reliability of the defocus amount by comparison with a plurality of levels divided by a plurality of threshold values.
The threshold value setting means for setting the plurality of threshold values and the threshold value setting means.
A candidate determination means for determining whether or not there are a plurality of candidates for the position of the focus lens from which the in-focus state can be obtained by using the pair of phase difference image signals.
When the candidate determination means determines that there are a plurality of the candidates, the false focus determination means for determining whether or not the position of the focus lens is in false focus by using the defocus amount in the standard region .
When the false focus determination means determines that the position of the focus lens is false focus, the reliability of the defocus amount corresponding to the position of the focus lens determined to be false focus . A focus adjusting device comprising: a control means for lowering the level of evaluation value. The evaluation value determining means calculates a standard deviation of the defocus amount calculated by using the correlation change amount of the pair of phase difference image signals, and compares the calculated standard deviation with the plurality of levels. The focus adjusting device according to claim 1 , wherein the reliability evaluation value is determined . The threshold value setting means sets, as the plurality of threshold values, a second threshold value having a value smaller than the first threshold value with respect to a predetermined first threshold value.
The focus adjusting device according to claim 1 or 2, wherein the second threshold value is changed according to the subject brightness of the output signal. The focus adjustment according to claim 1 or 2, wherein the control means lowers the level of the reliability evaluation value when the level of the reliability evaluation value is higher than a predetermined level. Device. The generation means generates a plurality of defocus amounts by performing processing by a plurality of filters having different bands.
The false focus determination means is characterized in that, among a plurality of filters having different bands, determination is performed using a defocus amount generated by performing processing by a predetermined filter band. 4. The focus adjusting device according to any one of 4. The focus adjusting device according to any one of claims 1 to 5 , wherein the false focus determination means makes a determination based on an image coincidence degree and a correlation change amount obtained by the generation means. An acquisition step of acquiring a pair of phase difference image signals having a phase difference according to the focus detection result of the subject image from the output signal of the image sensor, and
A generation step of generating a defocus amount for controlling the position of the focus lens by using a standard region in the pair of phase difference image signals acquired in the acquisition step and a narrow region narrower than the standard region .
An evaluation value determination step for determining the reliability evaluation value regarding the reliability of the defocus amount by comparison with a plurality of levels divided by a plurality of threshold values.
A candidate determination step for determining whether or not there are a plurality of candidates for the position of the focus lens from which the in-focus state can be obtained by using the pair of phase difference image signals.
When it is determined that there are a plurality of the candidates in the candidate determination step, the false focus determination step of determining whether or not the position of the focus lens is false focus is performed by using the defocus amount in the standard region . ,
When it is determined in the false focus determination step that the position of the focus lens is false focus, the reliability of the defocus amount corresponding to the position of the focus lens determined to be false focus. A focus adjustment method characterized by having a control step that lowers the level of the sex evaluation value. Image sensor and
The image pickup apparatus according to any one of claims 1 to 6 , further comprising the focus adjuster according to any one of claims 1 to 6, which adjusts the focus formed on the image pickup element .

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