JP2018036628A - Control device, imaging device, control method, program, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device capable of improving focusing accuracy and shortening a focus adjustment time. SOLUTION: A control device has an acquisition means (204a) for acquiring a first signal and a second signal corresponding to light fluxes passing through different pupil regions of an imaging optical system, and a first signal and a second signal. A calculation means (204b) that performs a plurality of filtering processes having different bands and calculates a plurality of defocus amounts and a plurality of reliabilitys based on the first signal and the second signal after each filtering processing, and a plurality of defocusing processes. It has a determination means (209) for determining the defocus amount used for focus adjustment from among the plurality of defocus amounts based on the difference in the focus amount and at least one of the plurality of reliabilitys. [Selection diagram] FIG. 10

Description

  The present invention relates to an imaging apparatus that performs focus adjustment by imaging plane phase difference AF.

  In recent years, as phase difference AF (imaging surface phase difference AF) using an image sensor, a method of acquiring a photographed image and performing focus detection using pixels of the image sensor has been proposed.

  Patent Document 1 discloses a configuration in which a plurality of photodiodes corresponding to one microlens are provided, and each photodiode receives light from different pupil planes of the photographing lens. With such a configuration, the imaging surface phase difference AF can be performed by comparing the outputs of the two photodiodes. In the imaging plane phase difference AF, band pass filter processing is performed on two (a pair of) image signals (A image signal and B image signal) of each pixel, and then the A image signal and the B image signal are related to a predetermined region. An image shift amount is calculated by performing a correlation operation, and a defocus amount is calculated based on the image shift amount.

  In Patent Document 2, a first filter process is performed on two image signals to calculate a defocus amount, and a second filter process is performed on the calculated defocus amount to obtain an evaluation value of the defocus amount. A configuration to generate is disclosed. Further, the focus state is evaluated based on the generated evaluation value, and focus adjustment is performed according to the evaluation result.

JP 2001-083407 A JP 2014-219549 A

  However, the defocus amount characteristic varies depending on the frequency band of the bandpass filter applied to the image signal. For example, when the frequency band is low, the defocus amount can be detected even in a large blurred state, but the accuracy of the defocus amount near the in-focus position is lowered. On the other hand, when the frequency band is high, the accuracy of the defocus amount near the in-focus position is high, but the defocus amount cannot be detected in a large blurred state.

  In Patent Document 2, an evaluation value of a defocus amount is generated by filter processing in a frequency band different from the frequency band of filter processing used for calculation of the defocus amount, and the focus state is evaluated using the evaluation value. Yes. However, only one frequency band is used as the frequency band of the bandpass filter for detecting the defocus amount. When the frequency band of the filter is set to a low frequency, the accuracy (focusing accuracy) of the defocus amount in the vicinity of the in-focus position is lowered. On the other hand, if the frequency band of the filter is set to a high frequency, a large blurred state cannot be detected, and thus it may take time to adjust the focus by moving the focus lens in the direction opposite to the in-focus position.

  Therefore, the present invention provides a control device, an imaging device, a control method, a program, and a storage medium that can improve the focusing accuracy and shorten the focus adjustment time.

  The control device according to one aspect of the present invention includes an acquisition unit configured to acquire a first signal and a second signal corresponding to light beams passing through different pupil regions of the imaging optical system, and the first signal and the second signal. A plurality of filtering processes having different bands, and calculating means for calculating a plurality of defocus amounts and a plurality of reliability based on the first signal and the second signal after the respective filter processes; And determining means for determining a defocus amount used for focus adjustment from the plurality of defocus amounts based on a difference in focus amount and at least one of the plurality of reliability levels.

  An imaging apparatus according to another aspect of the present invention includes an imaging device having a first photoelectric conversion unit and a second photoelectric conversion unit that receive light beams passing through different pupil regions of an imaging optical system, and the first photoelectric conversion unit. And acquisition means for acquiring the first signal and the second signal corresponding to each of the output signals from the second photoelectric conversion unit, and a plurality of filter processes having different bands with respect to the first signal and the second signal And calculating means for calculating a plurality of defocus amounts and a plurality of reliability levels based on the first signal and the second signal after the respective filter processing, a difference between the plurality of defocus amounts, and the plurality of reliability values Determination means for determining a defocus amount used for focus adjustment from the plurality of defocus amounts based on at least one of the degrees.

  According to another aspect of the present invention, there is provided a control method comprising: obtaining a first signal and a second signal corresponding to light beams passing through different pupil regions of an imaging optical system; and the first signal and the second signal. Performing a plurality of filter processes with different bands on each other, calculating a plurality of defocus amounts and a plurality of reliability levels on the basis of the first signal and the second signal after the respective filter processes; Determining a defocus amount used for focus adjustment from the plurality of defocus amounts based on the difference in amount and at least one of the plurality of reliability levels.

  A program according to another aspect of the present invention causes a computer to execute the control method.

  A storage medium according to another aspect of the present invention stores the program.

  Other objects and features of the invention are described in the following embodiments.

  According to the present invention, it is possible to provide a control device, an imaging device, a control method, a program, and a storage medium that can improve the focusing accuracy and shorten the focus adjustment time.

It is a block diagram of the imaging device in a 1st embodiment. It is a figure which shows the pixel structural example of (a) non-imaging surface phase difference system and (b) imaging surface phase difference system. It is a flowchart which shows operation | movement of the imaging device in 1st this embodiment. It is a flowchart which shows AF operation | movement in 1st Embodiment. It is a flowchart which shows the focus detection process in 1st Embodiment. It is explanatory drawing of the focus detection area | region in 1st Embodiment. It is explanatory drawing of the signal for AF (a pair of image signal) in 1st Embodiment. It is explanatory drawing of the relationship between the shift amount of AF signal and correlation amount in 1st Embodiment. It is explanatory drawing of the relationship between the shift amount of AF signal and correlation change amount in 1st Embodiment. It is a flowchart which shows selection of the defocus amount in 1st Embodiment. It is a flowchart which shows the taking over determination from large Def to medium Def in 1st Embodiment. It is a flowchart which shows the taking over determination from middle Def to small Def in 1st Embodiment. It is a block diagram of the imaging device in 2nd Embodiment. It is explanatory drawing of a cam locus. 10 is a flowchart illustrating an operation of the imaging apparatus according to the second embodiment. 10 is a flowchart illustrating an AF operation during zooming according to the second embodiment. It is a flowchart which shows the target position selection process in 2nd Embodiment. It is a flowchart which shows the target position selection process in 2nd Embodiment. It is explanatory drawing regarding the focus control during zoom in 2nd Embodiment. It is a flowchart which shows normal AF operation | movement in 2nd Embodiment. It is a flowchart which shows normal AF operation | movement in 2nd Embodiment. It is a flowchart which shows the safety MF operation | movement in 2nd Embodiment. It is a flowchart which shows selection of the defocus amount in 2nd Embodiment. It is a block diagram of the imaging device in 3rd Embodiment. It is a flowchart which shows the cam locus tracking process in 3rd Embodiment. 14 is a flowchart illustrating an AF operation during zooming according to the third embodiment. It is a flowchart which shows the AF process in 3rd Embodiment. It is explanatory drawing regarding the focus control during zoom in 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
First, the configuration of the imaging apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of an imaging apparatus 10 (lens-interchangeable camera system) in the present embodiment. The imaging device 10 includes a camera body 200 (imaging device body) and a lens device 100 (interchangeable lens) that can be attached to and detached from the camera body 200. The lens device 100 is detachably (replaceable) attached to the camera body 200 via a mount unit (not shown) having an electrical contact unit 106. Note that this embodiment can also be applied to an imaging apparatus in which a lens device and a camera body are integrally configured.

  101 is a photographing lens including a zoom mechanism, 102 is a diaphragm and shutter for controlling the amount of light, 103 is a focus lens for focusing on an image sensor 201 described later, 104 is a motor for driving the focus lens 103, and 105 is a lens controller. It is. Reference numeral 201 denotes an image sensor as light receiving means (photoelectric conversion means) that converts reflected light from a subject into an electrical signal. Reference numeral 202 denotes an A / D conversion unit including a CDS circuit that removes output noise of the image sensor 201 and a non-linear amplification circuit that is performed before A / D conversion. Reference numeral 203 denotes an image processing unit, 204 denotes an AF signal processing unit, and 205 denotes a format conversion unit. In the present embodiment, the AF signal processing unit 204 includes an acquisition unit 204a and a calculation unit 204b.

Reference numeral 206 denotes a high-speed built-in memory (DRAM) such as a random access memory (RAM), which is used as a high-speed buffer as temporary image storage means or as a working memory in image compression / decompression.
An image recording unit 207 includes a recording medium such as a memory card and its interface, and 208 is a timing generator. Reference numeral 209 denotes a system control unit that controls the system such as an imaging sequence, 210 denotes a lens communication unit that communicates between the camera body 200 and the lens apparatus 100, 211 denotes an AE processing unit, and 212 denotes an image display memory (VRAM). Reference numeral 213 denotes an image display unit that displays a shooting screen and a focus detection area at the time of shooting, in addition to the display of images, the display for assisting operations, and the display of the camera state.

  Reference numeral 214 denotes an operation unit for the user to operate the camera body 200, a menu switch for performing various settings such as a shooting function of the imaging apparatus 10 and settings for image playback, and operation modes of the shooting mode and the playback mode. Including changeover switches. Reference numeral 215 denotes a shooting mode switch for selecting a shooting mode such as a macro mode or a sports mode. Reference numeral 216 denotes a main switch for turning on the power to the system (imaging device 10). Reference numeral 217 denotes a switch (SW1) for performing a photographing standby operation such as AF or AE, and reference numeral 218 denotes a switch (SW2) for performing photographing after the operation of the switch SW1.

  The image sensor 201 includes a CCD sensor, a CMOS sensor, and the like, photoelectrically converts a subject image (optical image) formed via the imaging optical system of the lens apparatus 100, and outputs a pixel signal (image data). That is, the light beam incident from the image pickup optical system forms an image on the light receiving surface of the image pickup device 201 and is converted into a signal charge corresponding to the amount of incident light by the pixels (photodiodes) arranged in the image pickup device 201. 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 a drive pulse output from the timing generator 208 in accordance with a command from the system control unit 209.

  Each pixel of the image sensor 201 used in the present embodiment is provided for two (a pair) of photodiodes A and B and the pair of photodiodes A and B (sharing the photodiodes A and B). And a single microlens. That is, the image sensor 201 has a pair of photodiodes (first photoelectric conversion unit and second photoelectric conversion unit) for one microlens, and a plurality of microlenses are arranged in a two-dimensional manner. Each pixel divides incident light by a microlens to form a pair of optical images on the pair of photodiodes A and B, and the pair of photodiodes A and B uses a pair of AF signals that will be described later. Pixel signals (A image signal and B image signal) are output. Further, by adding the outputs of the pair of photodiodes A and B, an imaging signal (A + B image signal) can be obtained.

  An AF signal (focus detection) used for AF (imaging surface phase difference AF) by an imaging surface phase difference detection method by combining a plurality of A image signals and a plurality of B image signals output from a plurality of pixels, respectively. A pair of image signals as a signal for use) is obtained. An AF signal processing unit 204, which will be described later, performs a correlation operation on the pair of image signals to calculate a phase difference (image shift amount) that is a shift amount of the pair of image signals. The focus amount (and defocus direction) is calculated.

  Thus, the image sensor 201 photoelectrically converts an optical image formed by receiving the light beam that has passed through the imaging optical system of the lens apparatus 100 into an electrical signal, and outputs image data (image signal). The imaging element 201 of the present embodiment is provided with two photodiodes for one microlens, and can generate an image signal used for focus detection by the imaging plane phase difference AF method. Note that the number of photodiodes (divided PDs) sharing one microlens may be changed, such as providing four photodiodes for one microlens.

  2A schematically illustrates a configuration of a pixel that does not support the imaging surface phase difference AF method, and FIG. 2B schematically illustrates a configuration example of a pixel that supports the imaging surface phase difference AF method. 2A and 2B, a Bayer array is used, where R is a red color filter, B is a blue color filter, and Gr and Gb are green color filters. Show. In the pixel configuration of FIG. 2B corresponding to the imaging plane phase difference AF, one pixel (pixel indicated by a solid line) in the pixel configuration not corresponding to the imaging plane phase difference AF method shown in FIG. Two photodiodes A and B divided into two in the horizontal direction in FIG. 2B are provided. Photodiodes A and B (first photoelectric conversion unit and second photoelectric conversion unit) receive light beams that have passed through different pupil regions of the imaging optical system. As described above, the photodiode A and the photodiode B receive the light fluxes that have passed through different regions of the exit pupil of the photographing optical system, so the B image signal has a parallax with respect to the A image signal. In addition, one image signal (A image or B image signal) of the above-described imaging signal (A + B image signal) and the pair of parallax image signals also has parallax. Note that the pixel dividing method shown in FIG. 2B is an example, such as a configuration divided in the vertical direction in FIG. 2B, a configuration divided into two in the horizontal direction and the vertical direction (total of 4 divisions), and the like. Other configurations may be adopted. In addition, a plurality of types of pixels that are divided by different division methods in the same image sensor may be included. In the present embodiment, a configuration in which a plurality of photoelectric conversion units are arranged for one microlens and a pupil-divided light beam is incident on each photoelectric conversion unit is shown, but the present invention is limited to this. It is not a thing. For example, the configuration of the focus detection pixel may be a configuration in which one PD is provided under the microlens and the pupil division is performed by shielding the left and right or upper and lower sides with a light shielding layer. Further, a configuration may be employed in which a pair of focus detection pixels are discretely arranged in an array of a plurality of imaging pixels, and a pair of image signals are acquired from the pair of focus detection pixels.

  The imaging signal and AF signal read from the imaging element 201 are input to the A / D conversion unit 202. The A / D conversion unit 202 performs correlated double sampling for removing reset noise, gain adjustment, and digitization on the imaging signal and the AF signal. The A / D conversion unit 202 outputs the imaging signal to the image processing unit 203 and outputs the AF signal to the AF signal processing unit 204.

  The AF signal processing unit 204 (acquisition unit 204a) outputs AF signals (first signal (A image signal) and second signal (B image signal) as a pair of image signals) output from the A / D conversion unit 202. To get. The AF signal processing unit 204 (calculation unit 204b) performs correlation calculation based on the AF signal to calculate the image shift amount, and calculates the defocus amount based on the image shift amount. Further, the AF signal processing unit 204 (calculation unit 204b) calculates reliability information of the AF signal (the degree of coincidence of the two images, the steepness of the two images, the contrast information, the saturation information, the scratch information, and the like). The defocus amount and reliability information (reliability) calculated by the AF signal processing unit 204 are output to the system control unit 209. Details of the correlation calculation by the AF signal processing unit 204 will be described later.

  Next, with reference to FIG. 3, the operation of the imaging device 10 in the present embodiment will be described. FIG. 3 is a flowchart showing the operation of the imaging apparatus 10. Each step in FIG. 3 is executed by each unit mainly based on a command from the system control unit 209.

  First, in step S301, the system control unit 209 controls the AE processing unit 211 to perform AE processing on the output signal of the image processing unit 203. Subsequently, in step S302, the system control unit 209 determines whether or not the switch 217 (SW1) is on. If the switch 217 (SW1) is on, the process proceeds to step S303. On the other hand, if the switch 217 (SW1) is off, the process returns to step S301.

  In step S303, the system control unit 209 performs an AF operation. Details of the AF operation will be described later. Subsequently, in step S304, the system control unit 209 determines whether or not the switch 217 (SW1) is on. If the switch 217 (SW1) is on, the process proceeds to step S305. On the other hand, if the switch 217 (SW1) is off, the process returns to step S301.

  In step S305, the system control unit 209 determines whether the switch 218 (SW2) is on. If the switch 218 (SW2) is off, the process returns to step S304. On the other hand, if the switch 218 (SW2) is on, the process proceeds to step S306. In step S306, the system control unit 209 performs a shooting operation. Then, it returns to step S301.

  Next, the AF operation (step S303 in FIG. 3) in the present embodiment will be described in detail with reference to FIG. FIG. 4 is a flowchart showing the AF operation. Each step in FIG. 4 is mainly executed by the AF signal processing unit 204 and the system control unit 209.

  First, in step S401, the system control unit 209 controls the AE processing unit 211 to perform AE processing on the output signal of the image processing unit 203. In step S402, the AF signal processing unit 204 performs focus detection processing using a pair of image signals, and calculates a defocus amount and reliability. Details of the focus detection process will be described later.

  Subsequently, in step S403, the system control unit 209 determines whether or not the reliability calculated in step S402 (the reliability of the focus detection result) is higher than a preset second reliability threshold. If the reliability is higher than the second reliability threshold, the process proceeds to step S404. On the other hand, if the reliability is less than the second reliability threshold, the process proceeds to step S413. If the reliability is less than the second reliability threshold, the second reliability threshold is set to a value that cannot guarantee the accuracy of the defocus amount but can guarantee the focus position direction of the subject.

  In step S404, the system control unit 209 determines whether or not the defocus amount (detected defocus amount) calculated in step S402 is equal to or less than a preset second Def amount threshold value. When the detected defocus amount is equal to or smaller than the second Def amount threshold value, the process proceeds to step S405. On the other hand, when the detected defocus amount is larger than the second Def amount threshold value, the process proceeds to step S412. If the defocus amount is equal to or smaller than the second Def amount threshold value, the second Def amount threshold value is set so that the focus lens 103 is moved within the depth of focus within a predetermined number of times (for example, three times) after that. It is set to a controllable value (for example, an amount 5 times the depth of focus).

  In step S405, the system control unit 209 determines whether or not the focus lens 103 is in a stopped state (stopped). If the focus lens 103 is stopped, the process proceeds to step S406. On the other hand, if the focus lens 103 is not stopped, the process proceeds to step S410.

  In step S406, the system control unit 209 determines whether or not the reliability (the reliability of the focus detection result) calculated in step S402 is higher than a preset first reliability threshold. If the reliability is higher than the first reliability threshold, the process proceeds to step S407. On the other hand, if the reliability is less than the first reliability threshold, the process proceeds to step S410. The first reliability threshold is set so that the accuracy variation of the defocus amount is within a predetermined range (for example, within the depth of focus) if the reliability is equal to or higher than the first reliability threshold.

  In step S407, the system control unit 209 determines whether or not the defocus amount (detected defocus amount) calculated in step S402 is equal to or less than a preset first Def amount threshold value. When the detected defocus amount is equal to or smaller than the first Def amount threshold value, the process proceeds to step S408. On the other hand, when the detected defocus amount is larger than the first Def amount threshold value, the process proceeds to step S409. The first Def amount threshold is set so that the focus lens 103 is controlled within the depth of focus if the detected defocus amount is equal to or less than the first Def amount threshold.

  In step S408, the system control unit 209 determines that the focus state is the in-focus state, and ends this flow. On the other hand, in step S409, the system control unit 209 drives the focus lens 103 by the defocus amount (detected defocus amount) calculated in step S402, and then returns to step S402. By performing a series of operations in steps S405 to S409, when the reliability calculated in step S402 is higher than the first reliability threshold, the system control unit 209 defocuses again with the focus lens 103 stopped. The amount can be calculated.

  In step S410, the system control unit 209 drives the focus lens 103 by a predetermined ratio with respect to the defocus amount detected in step S402. Subsequently, in step S411, the system control unit 209 instructs the focus lens 103 to stop and returns to step S402.

  In step S412, the system control unit 209 drives the focus lens 103 by a predetermined ratio with respect to the defocus amount detected in step S402, and the process returns to step S402. The predetermined ratio is set so that the drive amount (lens drive amount) of the focus lens 103 is smaller than the defocus amount (for example, 80%). In addition, the lens speed to be set is set to be slower than the speed at which the lens can be driven by the set drive amount in, for example, the time of one frame. Thus, it is possible to avoid exceeding the focus position of the subject when the detected defocus amount is not correct. In addition, the next lens drive can be performed while driving the focus lens 103 without stopping (overlap control).

  In step S413, the system control unit 209 determines whether or not the out-of-focus condition is satisfied. If the out-of-focus condition is satisfied, the process proceeds to step S414. On the other hand, if the out-of-focus condition is not satisfied, the process proceeds to step S415. The out-of-focus condition is a condition in which the system control unit 209 determines that there is no subject to be focused. As the out-of-focus condition, for example, when lens driving is completed in the entire movable range of the focus lens 103, that is, when the focus lens 103 detects both the far and near lens ends and returns to the initial position. A condition is set.

  In step S414, the system control unit 209 determines that the focus state is the out-of-focus state, and ends this flow. On the other hand, in step S415, the system control unit 209 determines whether or not the focus lens 103 has reached the far or near lens end. If the focus lens 103 has reached the lens end, the process proceeds to step S416. If the focus lens 103 has not reached the lens end, the process proceeds to step S417.

  In step S416, the system control unit 209 reverses the driving direction (lens driving direction) of the focus lens 103, and returns to step S402. In step S417, the system control unit 209 drives the focus lens 103 in a predetermined direction, and returns to step S402. The driving speed of the focus lens 103 (focus lens speed) is set to the fastest speed within a range of lens speeds that do not pass the focus position when the defocus amount can be detected, for example.

  Next, the focus detection process (step S402 in FIG. 4) will be described in detail with reference to FIG. FIG. 5 is a flowchart showing the focus detection process. Each step in FIG. 5 is mainly executed by the AF signal processing unit 204 based on a command from the system control unit 209 or the system control unit 209.

  First, in step S <b> 501, the AF signal processing unit 204 (system control unit 209) sets an arbitrary range of focus detection areas in the image sensor 201. Subsequently, in step S502, the AF signal processing unit 204 acquires a pair of image signals (A image signal and B image signal) for focus detection from the image sensor 201 with respect to the focus detection region set in step S501. Subsequently, in step S503, the AF signal processing unit 204 performs row addition averaging processing in the vertical direction on the pair of image signals acquired in step S502. The effect of noise of the image signal can be reduced by the row addition averaging process. Subsequently, in step S504, the AF signal processing unit 204 performs filter processing for extracting a signal component in a predetermined frequency band from the pair of image signals subjected to the row addition averaging process in step S503.

  Subsequently, in step S505, the AF signal processing unit 204 calculates a correlation amount based on the pair of image signals subjected to the filter processing in step S504. Subsequently, in step S506, the AF signal processing unit 204 calculates a correlation change amount based on the correlation amount calculated in step S505. Subsequently, in step S507, the AF signal processing unit 204 calculates an image shift amount based on the correlation change amount calculated in step S505. Subsequently, in step S508, the AF signal processing unit 204 calculates the reliability of the image shift amount calculated in step S507. In step S509, the AF signal processing unit 204 converts the image shift amount into a defocus amount.

  Subsequently, in step S510, the system control unit 209 determines whether or not only the filter type has been calculated regarding the filter processing performed in step S504. If the filter processing has been completed for the number of types of filters, the process proceeds to step S511. On the other hand, if the calculation of the filter processing is not completed for the type of filter, the process returns to step S504. In the present embodiment, in the filter processing in step S504, for example, bandpass filters of three frequency bands (low frequency, middle frequency, and high frequency) having different bands are applied to a pair of image signals subjected to row addition averaging processing. The used processing (filter processing) is performed in the horizontal direction. However, the low-pass filter, the mid-pass filter, and the high-pass filter indicate relative levels of frequency components extracted by the filters, and do not indicate absolute levels. In step S510, the system control unit 209 determines whether the series of processing in steps S504 to S509 has been performed for all three frequency bands.

  In step S511, the system control unit 209 selects a defocus amount. That is, the system control unit 209 (determination unit) uses any combination of the defocus amount and the reliability among the combinations of the three defocus amounts and the reliability calculated by the series of processes in steps S504 to S509. Select (decide). In the present embodiment, the defocus amount calculated using the low-pass filter is large Def, the defocus amount calculated using the mid-range filter is medium Def, and the defocus amount calculated using the high-pass filter is Small Def. The selection of the defocus amount will be described later.

  Next, the focus detection area (AF area) set in step S501 in FIG. 5 will be described in detail with reference to FIG. FIG. 6 is an explanatory diagram of the focus detection area 602 on the pixel array 601 of the image sensor 201. Shift areas 603 on both sides of the focus detection area 602 are areas necessary for correlation calculation. Therefore, a region 604 obtained by combining the focus detection region 602 and the shift region 603 is a pixel region necessary for correlation calculation. In FIG. 6, p, q, s, and t are coordinates in the horizontal direction (x-axis direction), p and q are the x-coordinates of the start point and end point of the region 604 (pixel region), and s and t are The x-coordinates of the start point and end point of the focus detection area 602 are respectively shown.

  FIG. 7 is an explanatory diagram of AF signals (a pair of image signals) acquired from a plurality of pixels included in the focus detection area 602 of FIG. In FIG. 7, a solid line 701 is one of the pair of image signals (A image signal), and a broken line 702 is the other of the pair of image signals (B image signal). FIG. 7A shows the A image signal and the B image signal before the shift, and FIGS. 7B and 7C show the A image signal and the B image signal in the plus direction from the state of FIG. The state shifted in the minus direction is shown. When calculating the amount of correlation between a pair of image signals (A image signal indicated by a solid line 701 and B image signal indicated by a broken line 702), both the A image signal and the B image signal are set bit by bit in the direction of the arrow. shift.

  Next, a method for calculating the correlation amount will be described. First, as shown in FIGS. 7B and 7C, the A image signal and the B image signal are each shifted by 1 bit to calculate the sum of the absolute values of the differences between the A image signal and the B image signal. To do. The correlation amount COR [i] can be calculated using the following equation (1).

  In Expression (1), i is the shift amount, ps is the maximum shift amount in the negative direction, qt is the maximum shift amount in the positive direction, x is the start coordinate of the focus detection region 602, and y is the focus detection region 602. End coordinate.

  Here, the relationship between the shift amount and the correlation amount COR will be described with reference to FIG. FIGS. 8A and 8B are explanatory diagrams of the relationship between the shift amount and the correlation amount COR. FIG. 8B is an enlarged view of the region 802 in FIG. In FIG. 8A, the horizontal axis indicates the shift amount, and the vertical axis indicates the correlation amount COR. Among the regions 802 and 803 near the extreme value in the correlation amount 801 that changes with the shift amount, the degree of coincidence of the pair of image signals (A image signal and B image signal) becomes the highest in the shift amount corresponding to the smaller correlation amount. .

  Next, a method for calculating the correlation change amount will be described. In the present embodiment, the difference in the correlation amount at every other shift in the waveform of the correlation amount 801 shown in FIG. 8A is calculated as the correlation change amount. The correlation change amount ΔCOR [i] can be calculated using the following equation (2).

  Here, the relationship between the shift amount and the correlation change amount ΔCOR will be described with reference to FIG. FIGS. 9A and 9B are explanatory diagrams of the relationship between the shift amount and the correlation change amount ΔCOR. FIG. 9B is an enlarged view of the region 902 in FIG. In FIG. 9A, the horizontal axis indicates the shift amount, and the vertical axis indicates the correlation change amount ΔCOR. The correlation change amount 901 that changes with the shift amount changes from positive to negative in the regions 902 and 903. A state in which the amount of correlation change is 0 is called zero crossing, and the degree of coincidence between a pair of image signals (A image signal and B image signal) is the highest. For this reason, the shift amount giving the zero cross is the image shift amount.

  In FIG. 9B, reference numeral 904 denotes a part of the correlation change amount 901. With reference to FIG. 9B, a method of calculating the image shift amount PRD will be described. The shift amount (k−1 + α) giving the zero cross is divided into an integer part β (= k−1) and a decimal part α. The decimal part α can be calculated using the following equation (3) from the similar relationship between the triangle ABC and the triangle ADE in FIG.

  The integer part β can be calculated using the following formula (4) from FIG. 9B.

  That is, the image shift amount PRD can be calculated from the sum of the decimal part α and the integer part β. As shown in FIG. 9A, when there are a plurality of zero crossings of the correlation change amount ΔCOR, the one having the larger steepness of the change in the correlation change amount ΔCOR in the vicinity thereof is defined as the first zero cross. This steepness is an index indicating the ease of performing AF, and the greater the value, the easier it is to perform highly accurate AF. The steepness maxder can be calculated using the following equation (5).

  In the present embodiment, when there are a plurality of zero crosses of the correlation change amount, the first zero cross is determined based on the steepness, and the shift amount giving the first zero cross is set as the image shift amount.

Next, a method for calculating the reliability information (reliability) of the image shift amount will be described. The reliability of the image shift amount can be defined by the degree of coincidence (degree of coincidence of two images) fnclvl of a pair of image signals (A image signal and B image signal) and the steepness of the above-described correlation change amount ΔCOR. The reliability may be acquired from any value.
The degree of coincidence between the two images is an index representing the accuracy of the image shift amount, and here, the smaller the value, the better the accuracy. In FIG. 8B, 804 is a part of the correlation amount 801. The coincidence degree fnclvl of the two images can be calculated using the following equation (6).

  Next, the selection of the defocus amount (step S511 in FIG. 5) will be described with reference to FIG. FIG. 10 is a flowchart showing selection of the defocus amount. Each step in FIG. 10 is mainly executed by the system control unit 209.

  First, in step S1001, the system control unit 209 performs a handover determination from a large Def (first defocus amount), which will be described later, to a medium Def (second defocus amount). Subsequently, in step S1002, the system control unit 209 determines whether or not the handover from the large Def to the middle Def has been performed. If the handover from the large Def to the medium Def can be performed, the process proceeds to step S1003. On the other hand, if the handover from the large Def to the middle Def cannot be performed, the process proceeds to step S1007.

  In step S <b> 1003, the system control unit 209 performs a handover determination from medium def (second defocus amount), which will be described later, to small def (third defocus amount). Subsequently, in step S1004, the system control unit 209 determines whether or not the handover from the middle Def to the small Def has been performed. If the handover from the middle Def to the small Def can be performed, the process proceeds to step S1005. On the other hand, if the handover from the middle Def to the small Def cannot be performed, the process proceeds to step S1006.

  In step S1005, the system control unit 209 selects small def as the defocus amount used for driving the focus lens 103 (focus control), and ends this flow. In step S1006, the system control unit 209 selects medium Def as the defocus amount used for focus control, and ends this flow. In step S1007, the system control unit 209 selects large def as the defocus amount used for focus control, and ends this flow.

  Next, with reference to FIG. 11, the handover determination from large Def to medium Def (step S <b> 1001 in FIG. 10) will be described. Each step in FIG. 11 is mainly executed by the system control unit 209.

  First, in step S1101, the system control unit 209 determines whether or not the difference in defocus amount between the large Def and the medium Def is equal to or less than a preset first depth threshold (first threshold). If the difference in defocus amount between the large Def and the medium Def is equal to or smaller than the first depth threshold, the process proceeds to step S1102. On the other hand, if this difference is greater than the first depth threshold, the process proceeds to step S1104. The first depth threshold is set to, for example, an amount nine times the depth of focus so that it can be properly transferred from the large Def to the medium Def. Further, by setting the first depth threshold with reference to the focal depth (making it larger than the focal depth), it is possible to set a uniform threshold even if the F value or the focus detection region changes.

  In step S1102, the system control unit 209 determines that the medium Def reliability (second reliability) is greater than or equal to the large Def reliability (first reliability) and the medium Def reliability is the second reliability threshold. It is determined whether or not it is higher than (the threshold value used in the determination in step S403 in FIG. 4). If both of these conditions are satisfied, the process proceeds to step S1103. On the other hand, if at least one of the conditions is not satisfied, the process proceeds to step S1104.

  In step S1103, the system control unit 209 determines that the handover from the large Def to the middle Def can be performed, and ends the present flow. On the other hand, in step S1104, the system control unit 209 determines that the handover from the large Def to the medium Def cannot be performed, and ends this flow. Accordingly, in the process of moving the focus lens 103 from the large blur state to the small blur state, the handover from the large Def to the medium Def is performed based on the difference in defocus amount between the large Def and the medium Def and the respective reliability. It can be determined whether or not it is possible.

  Next, with reference to FIG. 12, the determination of taking over from the middle Def to the small Def (step S1003 in FIG. 10) will be described. Each step of FIG. 12 is mainly executed by the system control unit 209.

  First, in step S1201, the system control unit 209 determines whether or not the difference in defocus amount between the medium def and the small def is equal to or smaller than a preset second depth threshold (second threshold). If the difference in the defocus amount between the middle def and the small def is equal to or smaller than the second depth threshold, the process proceeds to step S1202. On the other hand, if this difference is greater than the second depth threshold, the process proceeds to step S1204. The second depth threshold is set to, for example, three times the depth of focus so that the medium Def can be appropriately transferred from the small Def. In addition, by setting the second depth threshold value based on the focal depth (making it larger than the focal depth), a uniform threshold value can be set even if the F value or the focus detection region changes. Further, the second depth threshold is set to a value smaller than the first depth threshold used in the determination in step S1101 of FIG. This is because the variation in detection of the defocus amount increases as small Def → medium Def → large Def, and as a result, the difference between medium Def and large Def becomes larger than the difference between small Def and medium Def. is there.

  In step S1202, the system control unit 209 determines that the reliability of the small Def is equal to or higher than the reliability of the medium Def, and both the reliability of the small Def and the reliability of the medium Def are both higher than the second reliability threshold value. It is determined whether or not. If all these conditions are satisfied, the process proceeds to step S1203. On the other hand, if at least one condition is not satisfied, the process proceeds to step S1204.

  In step S1203, the system control unit 209 determines that the handover from the middle Def to the small Def can be performed, and ends this flow. On the other hand, in step S1204, the system control unit 209 determines that the handover from the medium Def to the small Def cannot be performed, and ends this flow. Accordingly, in the process of moving the focus lens 103 from the small blur state to the in-focus position, the handover from the medium Def to the small Def is performed based on the difference in defocus amount between the medium Def and the small Def and the respective reliability. It can be determined whether or not it is possible.

  As described above, in the present embodiment, the control device includes the AF signal processing unit 204 (acquisition unit 204a, calculation unit 204b) and determination unit (system control unit 209). The acquisition means acquires a first signal (A image signal) and a second signal (B image signal) corresponding to light beams passing through different pupil regions of the imaging optical system. The calculating means performs a plurality of filter processes (band pass filter processes) with different bands on the first signal and the second signal, and a plurality of data are processed based on the first signal and the second signal after each filter process. A focus amount and a plurality of reliability levels are calculated. The determining unit determines a defocus amount used for focus adjustment (focus control) from the plurality of defocus amounts based on the difference between the plurality of defocus amounts and at least one of the plurality of reliability levels.

  Preferably, the plurality of filter processes include a first filter process for extracting the first signal and the second signal in the first frequency band (low band), and a second frequency band (middle band) higher than the first frequency band. Second filter processing for extracting the first signal and the second signal. The calculating means calculates the first defocus amount (large Def) and the first reliability (large Def) based on the first signal and the second signal after the first filter processing as the plurality of defocus amounts and the plurality of reliability levels. (Reliability) is calculated. The calculation means calculates a second defocus amount (medium Def) and a second reliability (medium Def reliability) based on the first signal and the second signal after the second filter processing. More preferably, when the difference between the first defocus amount and the second defocus amount is larger than the first threshold value (first depth threshold value), the calculation unit uses the first defocus amount as a defocus amount used for focus adjustment. The focus amount is determined (S1101, S1104). More preferably, the calculation means is a case where the second reliability is higher than the first reliability and the second reliability is higher than a predetermined reliability threshold (second reliability threshold), The second defocus amount is determined as a defocus amount used for focus adjustment. On the other hand, when the second reliability is lower than the first reliability, or when the second reliability is lower than a predetermined reliability threshold (second reliability threshold), the calculation means calculates the first defocus amount. Is determined as the defocus amount used for focus adjustment (S1102 to S1104).

  Preferably, the plurality of filter processes include a third filter process for extracting a first signal and a second signal in a third frequency band (high band) higher than the second frequency band. The calculating means calculates the third defocus amount (small Def) and the third reliability (small Def) based on the first signal and the second signal after the third filter processing as the plurality of defocus amounts and the plurality of reliability levels. (Reliability) is calculated. More preferably, when the difference between the second defocus amount and the third defocus amount is larger than the second threshold value (second depth threshold value), the calculation means uses the second defocus amount as a defocus amount used for focus adjustment. The focus amount is determined (S1201, S1204). More preferably, the calculation means is a case where the third reliability is higher than the second reliability, and each of the second reliability and the third reliability is a predetermined reliability threshold (second reliability threshold). ), The third defocus amount is determined as the defocus amount used for focus adjustment. On the other hand, when the third reliability is lower than the second reliability, or when the second reliability or the third reliability is lower than a predetermined reliability threshold, the calculation means calculates the second defocus amount, A defocus amount used for focus adjustment is determined (S1202 to S1204). More preferably, the second threshold is smaller than the first threshold. Preferably, the first threshold value and the second threshold value are set based on the depth of focus.

  In the present embodiment, in the process of moving the focus lens from the large blur state to the in-focus position, the defocus amount that can determine the direction of the focus position in the large blur state, and the high in the vicinity of the in-focus position. Use defocus amount with accuracy. Therefore, according to the present embodiment, it is possible to provide a control device, an imaging device, a control method, a program, and a storage medium that can improve the focusing accuracy and shorten the focus adjustment time.

  In the present embodiment, the system control unit 209 determines the defocus amount used for focus adjustment by using both the defocus amount difference and the defocus amount reliability, but only one of them is used. Thus, the defocus amount used for focus adjustment may be determined. In other words, in the determination of taking over from the large Def to the medium Def, it may be determined whether the large Def or the medium Def is used by omitting Step S1101 or Step S1102. Similarly, in the handover determination from medium Def to small Def, step S1201 or step S1202 may be omitted to determine whether medium Def or small Def is used.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.

  When the subject has low contrast or low brightness, addition of a plurality of frames or a plurality of lens movements improves the focusing accuracy but increases the time until focusing. In normal shooting, it is desirable to focus when the contrast is low or when the brightness is low even if the AF time is long. However, it is desirable to give priority to shortening the time to focus rather than focusing accuracy. There is a case. For example, as a manual focus (MF) mode in which a user can manually specify a focus lens position and perform shooting, a function that assists focusing by performing AF control in a minute range including the focus lens position specified by the user (safety) MF). Since this function is the MF mode, it is desirable that the shooting time lag is not prolonged by AF control.

  Also, when zooming from wide to tele, or from tele to wide, the zoom lens and focus lens are driven and controlled to trace the cam trajectory according to the subject distance, thereby obtaining a good image with no focus error. Can do. However, as shown in FIG. 14, the cam trajectory for each subject distance becomes denser as it approaches the wide position. For this reason, when zooming from wide to tele, the cam trajectory corresponding to the subject distance cannot be accurately selected, and the cam trajectory selected first may deviate from the cam trajectory corresponding to the subject distance. As a result, blurring occurs due to zooming. In addition, when detecting the defocus amount by the imaging surface phase difference AF method, a method of adding an image signal until a predetermined image signal value exceeds a threshold value is known. The time will be longer.

  Accordingly, in the second to fourth embodiments, an imaging apparatus capable of improving focusing accuracy and shortening AF time by making AF control different from that in the normal shooting mode during a specific shooting mode or zoom operation. The purpose is to provide. In the second embodiment, an explanation will be given of an imaging device that is a lens barrel that is integrated with a lens barrel and an imaging device.

<Overall configuration>
First, with reference to FIG. 13, an example of an imaging apparatus with a lens barrel in the present embodiment will be described. FIG. 13 is a block diagram of the imaging apparatus 1000 in the present embodiment. As shown in FIG. 13, an imaging apparatus 1000 with a lens barrel attached is configured around a camera control unit 1114 that controls the operation of the lens barrel and the entire imaging apparatus. Further, each operation of the imaging apparatus 1000 is executed based on a control program stored in an internal ROM and RAM (not shown) and various data necessary for control.

  First, the configuration of the portion related to the lens barrel will be described. The lens barrel includes a zoom lens 1101, an aperture 1102, a focus lens 1103, a zoom lens driving unit 1104, an aperture driving unit 1105, and a focus lens driving unit 1106. The zoom lens 1101 is driven by the zoom lens driving unit 1104 to change the focal length. A diaphragm 1102 is driven by a diaphragm driving unit 1105 and controls the amount of light incident on an image sensor 1107 described later. The focus lens 1103 is driven by a focus lens driving unit 1106 and adjusts a focus imaged on an image sensor 1107 described later. The zoom lens driving unit 1104, the aperture driving unit 1105, and the focus lens driving unit 1106 are controlled by the camera control unit 114, and determine the position of the zoom lens 1101, the opening amount of the aperture 1102, and the position of the focus lens 1103. . The camera control unit 1114 obtains lens control information from the zoom lens driving unit 1104, the aperture driving unit 1105, and the focus lens driving unit 1106.

  Next, the configuration of the part related to the imaging function for acquiring the imaging signal from the light beam that has passed through the imaging optical system will be described. The imaging apparatus 1000 includes an imaging device 1107, a CDS / AGC circuit 1108, a camera signal processing unit 1109, an AF signal processing unit 1110, a display unit 1111, a recording unit 1112, a camera control unit 1114, and a camera operation unit 1115. The imaging apparatus 1000 also includes a shooting mode switch 1116 for selecting a shooting mode such as a safety MF mode, a switch 1117 (SW1) for performing a shooting standby operation such as AF and AE, and a shooting switch 1118 for performing shooting after the operation of SW1. (SW2). In addition, the imaging apparatus 1000 includes an AE processing unit 1119.

  The image sensor 107 is a member as an image sensor, and includes a CCD, a CMOS sensor, or the like. The light beam that has passed through the imaging optical system of the lens barrel forms an image on the light receiving surface of the image sensor 107 and is converted into a signal charge corresponding to the amount of incident light by the photodiode. The signal charge accumulated in each photodiode is sequentially read out from the image sensor 1107 as a voltage signal corresponding to the signal charge based on a drive pulse supplied from the timing generator 1113 in accordance with a command from the camera control unit 1114. The video signal and AF signal read from the image sensor 107 are input to a CDS / AGC circuit 1108 that samples and adjusts the gain, and the video signal is input to the camera signal processing unit 1109 and the signal for the imaging plane phase difference AF is input. Each is output to the AF signal processing unit 1110.

  The camera signal processing unit 1109 performs various kinds of image processing on the signal output from the CDS / AGC circuit 1108 to generate a video signal. A display unit 1111 configured by an LCD or the like displays the video signal output from the camera signal processing unit 1109 as a captured image. The recording unit 1112 records the video signal from the camera signal processing unit 1109 on a recording medium such as a magnetic tape, an optical disk, or a semiconductor memory.

  The AF signal processing unit 1110 performs a correlation calculation based on the two image signals for AF output from the CDS / AGC circuit 1108, and performs defocus amount, reliability information (two-image coincidence, two-image steepness, contrast Information, saturation information, scratch information, etc.). Then, the AF signal processing unit 1110 outputs the calculated defocus amount and reliability information to the camera control unit 1114. In addition, the camera control unit 114 notifies the AF signal processing unit 110 of changes in settings for calculating these based on the acquired defocus amount and reliability information. The details of the defocus amount calculation are as described in the first embodiment with reference to FIGS. 5 to 9.

  A camera control unit 1114 performs control by exchanging information with the entire imaging apparatus 1000. In addition to the processing in the imaging apparatus 1000, the user performs operations such as power ON / OFF, setting change, start of recording, start of AF control, confirmation of recorded video, etc. according to input from the camera operation unit 1115. The various camera functions performed are performed.

<Reliability of focus detection results>
Next, the reliability of the focus detection result in this embodiment will be described. In the present embodiment, as in the first embodiment, the reliability is acquired from at least one of the coincidence degree fnclvl of the two images and the steepness of the correlation change amount ΔCOR. In the present embodiment, the reliability is calculated by the AF signal processing unit 1110 in FIG. Basically, when the calculated defocus amount can be determined to be reliable, the reliability is high, and the reliability decreases as it becomes unreliable. In this embodiment, the reliability is expressed by a numerical value from 1 to 4, with 1 being the highest reliability and 4 being the lowest reliability. Details of each reliability are as follows.

  The case where the reliability is “1” means that the contrast of the A image signal and the B image signal is high and the shapes of the A image signal and the B image signal are similar (the two image coincidence level is high). This is a case where the main subject image is in focus. In this case, the driving is performed with reliability of the defocus amount.

  When the reliability is “2”, the reliability of the A image signal and the B image signal is high although the reliability is not as high as “1”, and the A image signal and the B image signal have similar shapes, A state in which the main subject image is located near the in-focus within a certain error range is shown. In this case, the target position is determined based on the defocus amount and driving is performed.

  The case where the reliability is “3” is a correlation obtained by relatively shifting the A image signal and the B image signal, although the two-image coincidence level calculated by the AF signal processing unit 110 is lower than a predetermined value. The defocus direction is reliable. For example, the determination is often made in a state where the main subject is slightly blurred.

  When the defocus amount and the defocus direction are not reliable, the reliability is determined as “4”. For example, the contrast of the A image signal and the B image signal is low and the image matching level is low. This is often the case when the subject is greatly blurred, and it is difficult to calculate the defocus amount. In the present embodiment and the third embodiment described later, the reliability “3” is set as the second reliability threshold of the first embodiment. In other words, when the reliability is 1 or 2, it is determined that the reliability is greater than the second reliability threshold, and the takeover determination of large Def, medium Def, and small Def is performed.

  Next, the operation of the imaging apparatus 1000 will be described in detail with reference to FIGS. FIG. 15 is a flowchart for explaining the operation of the imaging apparatus 1000. First, in step S1601, the AE processing unit 1119 performs AE processing. In step S1602, the camera control unit 1114 performs an AF operation during zoom described later. In step S1603, the camera control unit 1114 determines the state of SW1 (117). If the state of SW1 is ON, the process proceeds to step S1604. On the other hand, if the state of SW1 is not ON, the process proceeds to step S1601.

  In step S1604, the camera control unit 1114 determines the state of the shooting mode SW116. If the shooting mode is the safety MF mode (second mode), the process proceeds to step S1606. On the other hand, if the shooting mode is not the safety MF mode, the process proceeds to step S1605. In step S1605, the camera control unit 1114 performs a normal AF operation described later (normal mode, first mode). In step S1606, the camera control unit 1114 performs a safety MF operation described later. Here, the normal mode (first mode) is a mode in which the focus control unit (camera control unit 1114) performs focus control over the entire movable range of the focus lens. The safety MF mode (second mode) is a mode in which focus control is performed within a predetermined range based on the focus lens position set by the user.

  In step S1607, the camera control unit 1114 determines the state of SW1 (117). If the state of SW1 is ON, the process proceeds to step S1608. On the other hand, if the state of SW1 is not ON, the process returns to step S1601. In step S1608, the camera control unit 1114 determines the state of SW2 (118). If the state of SW2 is ON, the process proceeds to step S1609. On the other hand, if the state of SW2 is not ON, the process returns to step S1607. In step S1609, the camera control unit 1114 performs a shooting operation and returns to step S1601.

  Next, with reference to FIG. 16, the AF operation during zooming in step S1602 of FIG. 15 will be described. FIG. 16 is a flowchart showing the AF operation during zooming. This processing is executed according to a computer program stored on the ROM in the camera control unit 1114. For example, it is executed in a readout cycle (every vertical synchronization period) of an imaging signal from the imaging device 1107 for generating one field image (hereinafter also referred to as one frame and one screen). Further, it may be repeated every a plurality of vertical synchronization periods (V rates).

  First, in step S1701, the AF signal processing unit 1110 checks whether the AF signal has been updated. If the AF signal has been updated, the process proceeds to step S1702, and the AF signal processing unit 11110 acquires the result (defocus amount and reliability). On the other hand, if the AF signal has not been updated in step S1701, this processing is terminated as it is.

  In step S1703, the camera control unit 1114 determines whether the zoom lens 101 is moving. Specifically, when the photographer operates the zoom operation lever or the like using the camera operation unit 1115, the camera control unit 1114 that detects the operation drives the zoom lens 1101. Therefore, the camera control unit 1114 grasps the movement state of the zoom lens 1101. If the zoom lens 101 is not moving in step S1703, the process proceeds to zoom target position selection processing in step S1704. On the other hand, if the zoom lens 1101 is moving in step S1703, the process proceeds to zoom target position selection processing in step S1705. Both the processes in steps S1704 and S1705 are processes for selecting a target position when moving the focus lens 1103 at the current control timing, and will be described in detail later.

  When the zoom lens 1101 is moving, the process proceeds to step S1706 after step S1705. In step S1706, the camera control unit 1114 predicts the focus lens position at the next control timing based on the target distance selected in step S1705. Specifically, as shown by the cam trajectory at each subject distance in FIG. 14, in order to maintain the focused state at a certain subject distance, the cam trajectory at the corresponding subject distance is traced in accordance with the change in the focal length. Thus, it is necessary to control the focus lens 1103. For this reason, in step S1706, the camera control unit 1114 determines the position at which the focus lens should be controlled at the next control timing in order to maintain the focus at the target position selected in step S1705. Determine based on the trajectory. In the present embodiment, since it is assumed that AF control processing is executed every vertical synchronization period, the focus lens position advanced by the time corresponding to the time is specified from the cam locus. In addition, the cam trajectory information in the present embodiment is stored in the ROM in the camera control unit 1114, and the cam trajectory of the subject distance not held on the ROM can be obtained by interpolation from the adjacent cam trajectory. . In step S1707, the camera control unit 1114 controls the focus lens driving unit 1106 to move the focus lens 1103 with respect to the selected and determined target position.

<Target position selection process when zoom is stopped>
Next, with reference to FIGS. 17A and 18A, the zoom stop target position selection processing in step S1704 in FIG. 16 will be described. FIG. 17A is a flowchart showing the zoom stop target position selection process executed by the camera control unit 1114. Each step in FIG. 17A is executed in accordance with a computer program stored on the ROM in the camera control unit 1114, as in the zooming AF operation.

  First, in step S1801a of FIG. 17A, the camera control unit 1114 determines whether or not the acquired reliability is “1” based on the reliability acquired in S1702 of FIG. If the reliability is “1” in step S1801a, the process proceeds to step S1806a. On the other hand, if the reliability is not “1”, the process proceeds to step S1802a. When the reliability is “1”, the accuracy of the detected defocus amount is high, and the focus can be achieved by controlling the focus lens at the target position calculated from the defocus amount. Therefore, in step S1806a, the camera control unit 1114 sets the focus lens position (detection position) calculated based on the detected defocus amount and the current focus lens position as the target position. In this embodiment, the method of moving the focus lens 1103 directly to the detection position is referred to as target drive (first drive). Thereafter, in step S1810a, the search flag is turned OFF and the process is terminated. In the present embodiment, a target position, which will be described later, is set at the infinite end or the closest end of the movable range of the focus lens 1103, and the movement for specifying the in-focus position while moving the focus lens 1103 greatly is searched drive (second drive). A flag indicating the execution state is called a search flag.

  Subsequently, in step S1802a, the camera control unit 1114 determines whether or not the acquired reliability is “2”. If the reliability is “2” in step S1802a, the process proceeds to step S1807a. On the other hand, if the reliability is not “2”, the process proceeds to step S1803a. When the reliability is “2”, it indicates a state in which the accuracy of the detected defocus amount includes a certain error. For this reason, in step S1807a, the camera control unit 1114 sets a value obtained by multiplying the detected position calculated based on the detected defocus amount and the current focus lens position by the coefficient γ as the target position. The coefficient γ is a numerical value less than 1, and γ assumed in the present embodiment is 0.8. Therefore, in step S1807a, a position that is 80% of the detected position is set as the target position. In this embodiment, the method of moving the focus lens 1103 so as not to reach the detection position (in other words, not to overrun) is referred to as defocus drive (third drive) in this embodiment. Thereafter, in step S1810a, the search flag is set to OFF, and the process ends.

  Subsequently, in step S1803a, the camera control unit 1114 determines whether or not the acquired reliability is “3”. When the reliability is “3” in step S1803a, the process proceeds to step S1808a. On the other hand, if the reliability is not “3”, the process proceeds to step S1804a. When the reliability is “3”, the accuracy of the detected defocus amount itself is low, but the defocus direction indicates a reliable state. For this reason, in step S1808a, the camera control unit 1114 sets the detected end of the defocus direction as a target position and performs search driving. In step S1811a, the search flag is set to ON, and the process ends. In step S1804a, the camera control unit 1114 determines whether the search flag is OFF. If the search flag is OFF in step S1804a, the process proceeds to step S1809a. On the other hand, if the search flag is ON, the process proceeds to step S1805a.

  When the reliability is not “3” in step S1803a, the reliability is “4” and the defocus amount and the defocus direction are not reliable. In this case, it is difficult to specify the in-focus position only with information obtained from the AF signal processing unit 1110. Therefore, in step S1809a, the camera control unit 1114 sets the end on the wide driving range side as the target position based on the positional relationship between the current focus lens position, the end on the infinite side of the focus lens 1103, and the end on the closest side. Then, search driving is performed. In step S1811a, the search flag is set to ON, and the process ends.

  In step S1805a, the camera control unit 1114 determines whether the focus lens 1103 has reached either the infinite end or the close end. If any end is reached in step S1805a, the process proceeds to step S1809a and the target position is set again. As described above, since the end on the wide driving range side is set as the target position, the target position is set on the opposite end when the end is reached. On the other hand, if the end has not been reached in step S1805a, the process is terminated as it is and search driving is continued.

  As described above, in the zoom stop target position selection process according to this embodiment, as shown in FIG. 18A, when the reliability is high, the target position based on the defocus amount is set. On the other hand, when the reliability is low, the target position is set to the end of the movable range of the focus lens 103. For this reason, as the movement of the entire AF, the lower the reliability is, the larger the focus position is, and the more the focus position is specified.

<Zoom target position selection process>
Next, with reference to FIGS. 17B and 18B, the zoom stop target position selection processing in step S1705 of FIG. 16 will be described. FIG. 17B is a flowchart illustrating a zoom target position selection process executed by the camera control unit 1114. Each step in FIG. 17B is executed in accordance with a computer program stored on the ROM in the camera control unit 1114 in the same manner as the zooming AF operation.

  First, in step S1801b of FIG. 17B, the camera control unit 1114 determines whether or not the acquired reliability is “1” based on the reliability acquired in S1702 of FIG. When the reliability is “1” in step S1801b, the process proceeds to step S1804b. On the other hand, if the reliability is not “1”, the process proceeds to step S1802b. When the reliability is “1”, the accuracy of the detected defocus amount is high, and the focus can be achieved by controlling the focus lens at the target position calculated from the defocus amount. Therefore, in step S1804b, the camera control unit 1114 sets the focus lens position (detection position) calculated based on the detected defocus amount and the current focus lens position as the target position.

  Subsequently, in step S1802b, the camera control unit 1114 determines whether or not the acquired reliability is “2”. If the reliability is “2” in step S1802b, the process proceeds to step S1805b. On the other hand, if the reliability is not “2”, the process proceeds to step S1803b. When the reliability is “2”, it indicates a state in which the accuracy of the detected defocus amount includes a certain error. Therefore, in step S1805b, the camera control unit 1114 sets, as a target position, a value obtained by multiplying the detected position calculated based on the detected defocus amount and the current focus lens position by the coefficient α. The coefficient α is a numerical value less than 1, and α assumed in the present embodiment is 0.8. Therefore, in step S1805b, a position that is 80% of the detected position is set as the target position.

  Subsequently, in step S1803b, the camera control unit 1114 determines whether or not the acquired reliability is “3”. When the reliability is “3” in step S1803b, the process proceeds to step S1806b. On the other hand, if the reliability is not “3”, the process proceeds to step S1807b. When the reliability is “3”, the accuracy of the detected defocus amount itself is low, but the defocus direction indicates a reliable state. For this reason, in step S1806b, the camera control unit 1114 sets, as the target position, a position shifted by the shift amount β in the defocus direction from the current position based on the defocus direction and the current focus lens position. Note that β assumed in the present embodiment is set to about 1 · F · δ on the basis of the focal depth F · δ (F: F value, δ: allowable circle of confusion).

  If the reliability is not “3” in step S1803b, that is, if the reliability is “4”, the process proceeds to step S1807b, and the camera control unit 1114 sets the target position to the current focus lens position. After selecting the target position via step S1804b, step S1805b, step S1806b, or step S1807b, the process proceeds to step S1808b. In step S1808b, the camera control unit 1114 calculates an actual lens driving amount (actual driving amount in the drawing) based on the target position determined in steps S1803b to S1807b and the current focus lens position. Then, the camera control unit 1114 determines whether or not the actual drive amount is larger than N · F · δ. If it is determined in step S1808b that the actual drive amount is greater than N · F · δ, the process proceeds to step S1809b. On the other hand, if it is determined that the actual drive amount is equal to or less than N · F · δ, the process is terminated.

  In step S1809b, the camera control unit 1114 changes the target position to the current position + N · F · δ so that the actual drive amount does not exceed NF · δ. As described above, in steps S1808b and S1809b, the camera control unit 1114 causes the predetermined lens when the focus change larger than the predetermined lens driving amount (N · F · δ) occurs regardless of the reliability of the defocus amount. The target position is corrected so as to be within the driving amount. Here, with respect to a predetermined lens driving amount N · F · δ, the coefficient N in this embodiment is set to 5, and when there is a possibility that a focus fluctuation of 5 · F · δ, that is, about 5 depths or more may occur, the target position To suppress focus fluctuation.

  Thus, in the zoom stop target position selection process according to the present embodiment, as shown in FIG. 18B, when the defocus amount reliability is high, the target position based on the defocus amount is set. On the other hand, when the reliability is low, the target position is set based on the current lens position. FIG. 18C shows the positional relationship of the focus lens 1103 at the current time t1 and the next control timing t2 when the target position is selected by the zoom target position selection process and a series of AF control processes are performed.

  P1 at time t1 indicates the current lens position and corresponds to the distance A. The target position in the case of the reliability 1 to 4 in FIG. 18B corresponds to (1) to (4) at time t1 in FIG. That is, the distance B when the reliability is “1”, the distance C when the reliability is “2”, the distance D when the reliability is “3”, and the same distance A as the current position when the reliability is “4”. is there. Further, as shown in step S1808b and step S1809b of FIG. 17B, when the target position is larger than a predetermined lens driving amount (NF · δ), the distance E is satisfied at (5) at time t1. To do. In this case, the distance F in (6) is corrected by the target position selection process during zoom stop.

  In the zoom stop target position selection process, the target positions (1) to (4) and (6) at the current time t1 are selected and determined according to the reliability of the defocus amount. In step S1706 of FIG. 16, the lens positions at time t2 at the next control timing are calculated from the cam trajectory. In step S1707, the focus lens is driven toward the target position at time t2.

  As described above, according to the present embodiment, when the target position is selected based on the defocus amount and its reliability, the focus lens is controlled based on a different selection rule during zooming than when zooming is not performed. The target position can be determined and controlled. That is, the focus control unit (camera control unit 1114) limits the drive range of the focus lens in accordance with the defocus amount and the reliability during the drive of the zoom lens. More specifically, when the focus control unit determines that the amount of movement of the focus lens is greater than a predetermined amount during driving of the zoom lens, the focus lens is controlled so that the amount of movement of the focus lens does not exceed the predetermined amount. Correct the target position. As a result, it is possible to suppress the occurrence of a sudden focus change during zooming and maintain the continuity of the focus change. The zoom AF operation also provides focus tracking performance during zoom operation without adding multiple frames, even if the reliability is low despite being in the vicinity of the focus when a low-contrast subject or at low illuminance. Prioritize.

  Next, with reference to FIGS. 19A and 19B, the normal AF operation in step S1605 of FIG. 15 will be described. FIGS. 19A and 19B are flowcharts showing the normal AF operation.

  First, in step S2001 in FIG. 19A, the AE processing unit 1119 performs AE processing. Subsequently, in step S2002, the camera control unit 1114 initializes the frame addition number to zero. The frame addition number is used to determine how many frames are added to the focus detection results detected so far. Subsequently, in step S2003, the camera control unit 1114 initializes the lens drive count to zero. The number of times of lens driving is to determine how many times lens driving in step S2012 described later has been performed. Subsequently, in step S2004, the camera control unit 1114 performs focus detection processing to detect the defocus amount and the reliability. The focus detection process will be described later.

  Subsequently, in step S2005, the camera control unit 1114 determines whether or not the reliability of the result detected in step S2004 is larger than the second reliability threshold (that is, whether or not the reliability is “1” or “2”). ). If the reliability is greater than the second reliability threshold, the process proceeds to step S2006. On the other hand, when the reliability is equal to or lower than the second reliability threshold (that is, when the reliability is neither “1” nor “2”), the process proceeds to step S2025. In step S2006, the camera control unit 1114 determines whether the defocus amount detected in step S2004 is equal to or smaller than a preset second Def amount threshold value. If the detected defocus amount is equal to or smaller than the second Def amount threshold value, the process proceeds to step S2007. On the other hand, if the defocus amount is larger than the second Def amount threshold value, the process proceeds to step S2023 in FIG. If the defocus amount is equal to or smaller than the second Def amount threshold value, the second Def amount threshold value is to control the focus lens within the depth of focus within a predetermined number of times (for example, three times) after that. Is set to such a value that can be (for example, an amount five times the depth of focus).

  In step S2007 of FIG. 19A, the camera control unit 1114 determines whether or not the focus lens 1103 is in a stopped state. If the focus lens 1103 is in a stopped state, the process proceeds to step S2008. On the other hand, if the focus lens 1103 is not stopped, the process proceeds to step S2015. In step S2008, the camera control unit 1114 determines whether or not the reliability of the result detected in step S2004 is “1”. If the reliability is “1”, the process proceeds to step S2009. On the other hand, if the reliability is not “1”, the process proceeds to step S2015.

  In step S2009, the camera control unit 1114 determines whether the lens driving frequency is equal to or greater than a first driving frequency threshold value. If the lens drive count is equal to or greater than the first drive count threshold value, the process proceeds to step S2011. On the other hand, if the lens driving frequency is smaller than the first driving frequency threshold value, the process proceeds to step S2010. The first driving frequency threshold sets the number of times that the lens can be driven to the vicinity of the in-focus position (for example, within the depth of focus) when the threshold is equal to or less than the second Def threshold. For example, in the normal AF operation, the driving frequency threshold 1 is set to 3 times.

  In step S2010, the camera control unit 1114 determines whether or not the defocus amount detected in step S2004 is equal to or less than a preset first def amount threshold value. If the defocus amount is equal to or smaller than the first Def amount threshold value, the process proceeds to step S2011. On the other hand, if the defocus amount is larger than the first Def amount threshold value, the process proceeds to step S2012. The first Def amount threshold is set so that the focus lens is controlled within the depth of focus if the detected defocus amount is equal to or less than the first Def amount threshold.

  In step S2011, the camera control unit 1114 determines that the in-focus state is in effect, and ends this flow. In step S2012, the camera control unit 1114 drives the focus lens 1103 by the defocus amount detected in step S2004, and then proceeds to step S2013. In step S2013, the camera control unit 1114 increments the number of lens driving times. Subsequently, in step S2014, the camera control unit 1114 initializes the frame addition number to 0, and the process returns to step S2004.

  In step S2015, the camera control unit 1114 determines whether the detected defocus amount is equal to or smaller than a third Def amount threshold value. When the detected defocus amount is equal to or smaller than the third Def amount threshold value, the process proceeds to step S2016. On the other hand, when the detected defocus amount is larger than the third Def amount threshold value, the process proceeds to step S2019. In step S2016, the camera control unit 1114 drives the focus lens 103 by a predetermined ratio with respect to the defocus amount detected in step S2004. Subsequently, in step S2017, the camera control unit 1114 instructs the focus lens 1103 to stop. Subsequently, in step S2018, the camera control unit 1114 initializes the frame addition number to 0, and the process returns to step S2004.

  In step S2019 in FIG. 19B, the camera control unit 1114 instructs the focus lens 1103 to stop. Subsequently, in step S2020, the camera control unit 1114 increments the frame addition number. Subsequently, in step S2021, the camera control unit 1114 adds the defocus amounts for a plurality of frames detected so far. Here, the frame subject to frame addition is determined so as to be the frame addition number incremented in step S2020 including this time.

  Subsequently, in step S2022, the camera control unit 1114 determines whether or not the frame addition number is greater than or equal to the frame addition number threshold value. If the frame addition number is equal to or greater than the frame addition number threshold, the process advances to step S2009. On the other hand, if the frame addition number is smaller than the frame addition number threshold, the process returns to step S2004. The frame addition number threshold is set by the number of frames that can obtain sufficient AF accuracy by averaging, and is set to, for example, four times. Further, the added defocus amount is averaged by using the number of frame additions, and in step S2010 immediately after that, determination is performed based on the defocus amount obtained by addition averaging.

  Subsequently, in step S2023, the camera control unit 1114 drives the focus lens 1103 by a predetermined ratio with respect to the defocus amount detected in step S2004. Here, the predetermined ratio is set so that the lens driving amount becomes smaller than the defocus amount (for example, 80%). Also, the lens speed to be set is set to be slower than the speed at which the lens can be driven by the lens driving amount set in, for example, the time of one frame. This prevents the subject focus position from being exceeded when the detected defocus amount is not correct, and allows the next lens drive to be performed while driving the lens without stopping (overlap control). ). Subsequently, in step S2024, the camera control unit 1114 initializes the frame addition number to 0, and the process returns to step S2004.

  In step S2025, the camera control unit 1114 initializes the frame addition number to zero. Subsequently, in step S2026, the camera control unit 1114 determines whether or not the out-of-focus condition is satisfied. If the out-of-focus condition is satisfied, the process proceeds to step S2027. On the other hand, if the out-of-focus condition is not satisfied, the process proceeds to step S2028. The out-of-focus condition is a condition for determining that there is no subject to be focused. As an out-of-focus condition, for example, when lens driving is completed in the entire movable range of the focus lens 1103, that is, when the focus lens 1103 detects both the far and near lens ends and returns to the initial position. Set conditions.

  In step S2027, the camera control unit 1114 determines that the camera is out of focus and ends this flow. In step S2028, the camera control unit 1114 determines whether or not the focus lens 1103 has reached the far or near lens end. If the focus lens 1103 has reached the lens end, the process proceeds to step S2029. On the other hand, if the focus lens 1103 has not reached the lens end, the process advances to step S2030. In step S2029, the camera control unit 1114 reverses the driving direction of the focus lens 1103 and returns to step S2004. In step S2030, the camera control unit 1114 drives the focus lens 1103 in a predetermined direction, and the process returns to step S2004. As the focus lens speed, for example, the fastest speed is set within a lens speed range that does not pass the focus position when the defocus amount can be detected.

  As described above, in the normal AF operation, when the reliability is low despite being in the vicinity of the focus in a low-contrast subject or at low illuminance, the focus performance is longer than the AF time unlike the zoom AF operation. Prioritize and add for multiple frames. Also, the AF control method based on the reliability is different from the zoom AF operation.

  Next, the safety MF operation in step S1606 in FIG. 15 will be described with reference to FIG. FIG. 20 is a flowchart showing the safety MF operation.

  Steps S2101 to S2105 are the same as steps S2001 to S2005 during the normal AF operation, and thus description thereof is omitted. If the reliability is greater than the second reliability threshold, the process advances to step S2106. On the other hand, when the reliability is equal to or lower than the second reliability threshold, this flow ends. In the case of the normal AF operation, the lens is driven in a predetermined direction when the reliability is equal to or less than the second reliability threshold value. However, in the safety MF operation, it is necessary to photograph near the current focus lens position. The safety MF operation is terminated without driving the focus lens.

  In step S2106, the camera control unit 1114 determines whether or not the defocus amount detected in step S2104 is equal to or smaller than a preset fourth def amount threshold (defocus amount threshold). If the defocus amount is equal to or smaller than the fourth Def amount threshold value, the process advances to step S2107. On the other hand, when the defocus amount is larger than the fourth Def amount threshold value, this flow is ended. Unlike the second Def amount threshold value in the normal AF operation, the fourth Def amount threshold value makes it difficult to understand the focus variation on the display unit 1111 even if the focus lens is driven based on the fourth Def amount threshold value. Set as a proper threshold. As the fourth Def amount threshold, for example, an amount three times the depth of focus is set.

  In step S2107, the camera control unit 1114 determines whether the reliability of the result detected in step S2104 is “1”. If the reliability is “1”, the process advances to step S2108. On the other hand, if the reliability is not “1”, the process proceeds to step S2113. In step S2108, the camera control unit 1114 determines whether or not the lens driving frequency is equal to or greater than a second driving frequency threshold. When the lens driving frequency is equal to or greater than the second driving frequency threshold, this flow ends. On the other hand, if the lens driving frequency is smaller than the second driving frequency threshold value, the process advances to step S2109. The second drive frequency threshold is set to be smaller than the first drive frequency threshold in the normal AF operation, for example, set to 1 time. As a result, the number of lens driving operations can be reduced in the safety MF operation, and the AF time can be shortened. Further, in the safety MF operation, since the focus lens is moved in the vicinity of the in-focus position by the user in advance, the lens can be driven to the in-focus position even if the number of lens driving is small. Steps S2109 to S2112 are the same as steps S2010 and S2012 to S2014 during the normal AF operation, and will not be described in detail. However, when the detected defocus amount is equal to or smaller than the first Def amount threshold value, this flow ends. On the other hand, if the defocus amount is larger than the first Def amount threshold, the focus lens 103 is driven based on the detected defocus amount, the lens drive count is incremented, the frame addition number is initialized to 0, and the process proceeds to step S2104. Return.

  In step S <b> 2113, the camera control unit 1114 determines whether the lens driving frequency is equal to or greater than a second driving frequency threshold value. When the lens driving frequency is equal to or greater than the second driving frequency threshold, this flow ends. On the other hand, if the lens driving frequency is smaller than the second driving frequency threshold value, the process advances to step S2114. As a result, even when the conditions for performing frame addition are satisfied, the number of frame additions and the number of lens driving operations can be limited to a small number, and the AF time can be shortened.

  In step S2114, the camera control unit 1114 increments the frame addition number. In step S2115, the camera control unit 1114 adds the defocus amounts for a plurality of frames detected so far. Here, the frame to be subjected to frame addition is determined to be the frame addition number incremented in step S2114 including this time. Subsequently, in step S2116, the camera control unit 1114 determines whether or not the frame addition number is equal to or greater than the frame addition number threshold value. If the frame addition number is equal to or greater than the frame addition number threshold value, the process advances to step S2117. On the other hand, if the frame addition number is smaller than the frame addition number threshold, the process returns to step S2104. Here, as the frame addition number threshold, as in the case of the normal AF operation, the number of frames for which sufficient AF accuracy can be obtained by averaging is set, for example, four times.

  In step S2117, the camera control unit 1114 determines whether or not the addition average defocus amount obtained by averaging the defocus amounts added in step S2115 by the frame addition number is equal to or less than the fourth Def amount threshold value. If the addition average defocus amount is equal to or smaller than the fourth Def amount threshold value, the process advances to step S2108. On the other hand, when the addition average defocus amount is larger than the fourth Def amount threshold value, this flow ends. In step S2109 immediately after the determination in step S2117, the camera control unit 1114 performs the determination based on the defocus amount obtained by addition averaging. Accordingly, AF control can be performed in a range in which it is difficult to understand the focus variation on the display unit 1111 even when the focus lens is driven.

  As described above, in the safety MF operation, when the reliability is low despite being in the vicinity of in-focus in a low-contrast subject or in low illumination, priority is given to the in-focus performance over the AF time. Is different from the zoom AF operation. In addition, since it is necessary to shorten the AF time in the MF mode, the number of lens driving after frame addition is different from the normal AF operation (the number of times is smaller than that in the normal AF operation). Also, the AF control method based on the reliability is different from the zoom AF operation and the normal AF operation.

  Next, selection of the defocus amount in step S511 of FIG. 5 will be described with reference to FIG. First, in step S2201, the camera control unit 1114 determines the state (shooting mode) of the shooting mode SW 1116. If the shooting mode is the safety MF mode, the process proceeds to step S2206, and a small Def is selected. As described above, when the photographing mode is the safety MF mode, the small Def is always selected on the assumption that the focus lens is set in the vicinity of the in-focus position by the user in advance. On the other hand, if the shooting mode is not the safety MF mode, the process proceeds to step S2202. Note that steps S2202 to S2208 in FIG. 21 are the same as steps S1001 to S1007 in FIG.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In the present embodiment, an example in which the present invention is applied to an imaging apparatus in which the lens barrel and the imaging apparatus can be separated is shown.

<Overall configuration>
First, with reference to FIG. 22, an example of the imaging apparatus in the present embodiment will be shown. FIG. 22 is a block diagram of the imaging apparatus 2000 in the present embodiment. As illustrated in FIG. 22, the imaging device 2000 includes a lens device 1100 and an imaging device main body 1200. In the imaging apparatus 2000, a lens control unit 1217 that controls the overall operation of the lens apparatus 1100 and a camera control unit 1114 that controls the overall operation of the imaging apparatus main body 1200 communicate information.

  First, the configuration of the lens apparatus 1100 will be described. The lens apparatus 1100 includes a zoom lens 1101, an aperture 1102, a focus lens 1103, a zoom lens position detection unit 1204, an aperture drive unit 1105, a focus lens drive unit 1106, a lens control unit 1217, and a lens operation unit 1218. The zoom lens 1101 is manually operated by a zoom ring member (not shown) to change the focal length. At this time, the position of the zoom lens 1101 is detected by the zoom lens position detection unit 1204 and used for controlling the lens apparatus 1100 and the imaging apparatus main body 1200. A diaphragm 1102 is driven by a diaphragm driving unit 1105 and controls the amount of light incident on an image sensor 1107 described later.

  The focus lens 1103 is driven by a focus lens driving unit 1106 and adjusts a focus imaged on an image sensor 1107 described later. The aperture driving unit 1105 and the focus lens driving unit 1106 are controlled by the lens control unit 1217 to determine the aperture amount of the aperture 1102 and the position of the focus lens 1103. When there is a user operation through the lens operation unit 1218, the lens control unit 1217 performs control according to the user operation. The lens control unit 1217 controls the aperture driving unit 1105 and the focus lens driving unit 1106 according to a control command and control information received from a camera control unit 1114 described later, and transmits lens control information to the camera control unit 1114. To do.

  Note that the lens control unit 1217 of the lens apparatus 1100 according to the present embodiment holds the cam locus information shown in FIG. 14 in a ROM (not shown) provided therein. When the zoom lens position detection unit 1204 detects a change in the position of the zoom lens 1101, the lens control unit 1217 controls the focus lens 1103 so as to maintain a focused state in a cam track following process described later. .

  Next, the configuration of the imaging apparatus main body 1200 will be described. The basic configuration of the imaging apparatus main body 1200 is the same as the configuration of the imaging apparatus 1000 described in the second embodiment with reference to FIG. However, in the present embodiment, the processing content of the camera control unit 1114 is different from that of the second embodiment.

  A camera control unit 1114 performs control by exchanging information with the entire imaging apparatus main body 1200. In addition to the processing in the imaging apparatus main body 1200, the user can turn on / off the power, change settings, start recording, start AF control, check recorded video, etc. according to input from the camera operation unit 1115. Perform the various camera functions that were operated. In addition, as described above, the camera control unit 1114 exchanges information with the lens control unit 1217 in the lens apparatus 1100, sends lens control commands and control information, and acquires information in the lens. Different from the second embodiment.

<Cam locus tracking process>
Next, with reference to FIG. 23, a cam track following process performed by the lens control unit 1217 will be described. FIG. 23 is a flowchart showing the cam track following process executed by the lens control unit 1217. This process is executed according to a computer program stored on the ROM in the lens control unit 1217. This processing is periodically performed by the lens control unit 1217, and in this embodiment, is performed at a cycle of 10 msec.

  First, in step S2601 of FIG. 23, the lens control unit 1217 acquires the current position information of the zoom lens 1101 from the zoom lens position detection unit 1204. Subsequently, in step S2602, the lens control unit 1217 acquires the current position information of the focus lens 1003 from the focus lens driving unit 1106. In step S2603, the lens control unit 1217 compares the previously acquired zoom lens position with the zoom lens position acquired at the previous control timing, and determines whether zooming is in progress based on the change. . If the zoom is being performed in step S2603, the process proceeds to step S2604. On the other hand, if the zoom is not in progress, this flow is terminated.

  In step S2604, the lens control unit 1217 determines the target position of the focus lens 1103 at the current control timing. Specifically, the lens control unit 1217 corresponds to the tracking subject distance at the current focal length based on the zoom lens position acquired in step S2601 and the subject distance (following subject distance) that is a target when the cam track tracking is performed. Specify the focus lens position. Note that the tracking subject distance at the time of cam track tracking is updated when the lens control unit 1217 controls the focus lens 1103 via the focus lens driving unit 1106. Therefore, it is updated both when the focus lens 1103 is controlled inside the lens apparatus 1100 by the lens control unit 1217 as in the cam track following process and when the focus lens 1103 is controlled by an instruction from the camera control unit 1114. The

  In step S2605, the lens control unit 1217 drives the focus lens 1103 by the difference between the focus lens position acquired in step S2602 and the target position determined in step S2604. Subsequently, in step S2606, the lens control unit 1217 stores the subject distance corresponding to the position after driving the focus lens 1103 in the recording unit 1112 as the tracking subject distance, and ends this flow.

  Next, with reference to FIGS. 26C and 26D, the movement of the focus lens 1103 when the series of cam locus tracking processes so far are performed will be described. FIG. 26C is a diagram showing the movement that the focus lens 1103 follows based on the cam trajectory information when the focal length changes, and P2 shows the current position of the focus lens 1103 at a certain control timing. In FIG. 26C, the focus lens 1103 is subjected to cam track tracking processing with the tracking subject distance as the distance A. FIG. 26D is an enlarged view of part of FIG. When the movement of the focus lens 1103 is captured on a shorter time axis, the focus lens 1103 is controlled so as to periodically follow the cam locus of the distance A by the cam locus following process described above. By repeating this follow-up control to the cam trajectory, the subject distance can be maintained even when the focal length changes.

<AF operation during zooming>
Next, with reference to FIG. 24, the AF operation during zooming performed by the camera control unit 1114 will be described. FIG. 24 is a flowchart showing the AF operation during zooming performed by the camera control unit 1114. This processing is executed according to a computer program stored on the ROM in the camera control unit 1114. For example, it is executed in a readout cycle (every vertical synchronization period) of an imaging signal from the imaging device 1107 for generating one field image (hereinafter also referred to as one frame and one screen). Further, it may be repeated every a plurality of vertical synchronization periods (V rates).

  In steps S2701 to S2705 in FIG. 24, the focus lens target selection processing is performed. Steps S2701 to S2705 are the same as steps S1701 to S1705 in FIG. 16 of the second embodiment, and a description thereof will be omitted. After step S2704 or step S2705 ends, the process proceeds to step S2706, the focus lens is driven, and this flow is ended. This flow differs from the flow during zooming in the second embodiment (the flow in FIG. 16) in that step S1706 is not provided.

<Target selection process at zoom stop>
Since the zoom stop target selection process of the present embodiment is the same as that of the second embodiment, description thereof is omitted. FIG. 26A shows the target position set in the zoom stop target position selection process in this embodiment, which is the same as FIG. 18A.

<Zoom target position selection process>
Next, the zoom target position selection process in step S2705 in FIG. 24 will be described with reference to FIGS. 25 and 26B, 26C, and 26D. FIG. 25 is a flowchart illustrating the zoom AF process performed by the camera control unit 1114. Each step in FIG. 25 is executed in accordance with a computer program stored on the ROM in the camera control unit 1114 in the same manner as the AF control process.

  The zoom target position selection process according to the second embodiment is that the process is terminated without setting the target position when the reliability is not “3” in step S2803b. And different. Steps S2801b to S2806b in the flowchart are the same as steps S1801b to S1806b in FIG.

  After selecting the target position via step S2804b, step S2805b, or step S2806b, the process proceeds to step S2807b. Steps S2807b and S2808b are the same as steps S1808b and S2808b of FIG. 17, and if the actual lens driving amount (actual driving amount in the figure) is larger than N · F · δ, the actual driving amount is N · F · δ. To do. Note that the coefficient N in this embodiment is set to 5, and when there is a possibility that a focus fluctuation of 5 · F · δ, that is, about 5 depths or more may occur, the target position is corrected to suppress the focus fluctuation. After correcting the target position, this flow ends.

  As described above, in the zoom AF process according to the present embodiment, as shown in FIG. 26B, when the reliability of the defocus amount is high, the camera control unit 1114 is based on the detected defocus amount. The focus lens 1103 is controlled to the target position. On the other hand, when the reliability is low, the camera control unit 1114 controls the focus lens 1103 to a target position based on the current lens position. Note that, when the reliability is such that the in-focus position cannot be specified, the camera control unit 1114 controls the focus lens 1103 not to be explicitly driven.

  FIG. 26C is a diagram showing a movement that the focus lens 1003 follows based on the cam trajectory information when the focal length is changed, and P2 is a current position at a certain control timing. In FIG. 26C, the focus lens 1003 is subjected to a cam track tracking process by the lens control unit 1217 of the lens apparatus 1100 with the tracking subject distance as the distance A independently of the instruction of the camera control unit 1114 of the imaging apparatus main body 1200. It shows that.

  (1) to (6) in FIG. 26C correspond to the reliability of the defocus amount when the above-described zoom AF process is performed by the camera control unit 1114 at the current control timing. The relationship of the drive target position of the focus lens 1103 is shown. The target positions in the case of reliability 1 to 4 in FIG. 26B correspond to (1) to (4) in FIG. That is, the distance B when the reliability is “1”, the distance C when the reliability is “2”, the distance D when the reliability is “3”, and the same distance A as the current position when the reliability is “4”. Yes, the focus lens 1103 is not explicitly driven by the camera control unit 1114. Similarly to FIG. 18C, when the target position is larger than the predetermined lens driving amount (N · F · δ), it becomes (5) in FIG. 26C, which corresponds to the distance E, and (6) The distance F is corrected. As described above, the lens apparatus 1100 that performs the cam locus tracking process and the imaging apparatus main body 1200 that corrects the focus position according to the defocus amount and the reliability thereof operate in conjunction with each other, so that focus control during zooming is performed. Realized.

  According to this embodiment, when the target position is selected based on the defocus amount and its reliability, the target position for controlling the focus lens is determined based on a selection rule that is different from the case where zooming is not performed during zooming. It becomes possible to control. That is, the focus control unit (camera control unit 1114) limits the drive range of the focus lens in accordance with the defocus amount and the reliability during the drive of the zoom lens. More specifically, when the focus control unit determines that the amount of movement of the focus lens is greater than a predetermined amount during driving of the zoom lens, the focus lens is controlled so that the amount of movement of the focus lens does not exceed the predetermined amount. Correct the target position. As a result, it is possible to suppress the occurrence of a sudden focus change during zooming and maintain the continuity of the focus change. In this embodiment, the zoom lens 1101 is manually operated. However, the present invention is not limited to this. For example, as in the second embodiment, the lens apparatus 1100 may include a zoom lens driving unit, and the lens control unit 1217 may control this. Further, a configuration in which an independent zoom lens driving unit is detachable from the lens apparatus 1100 may be employed. In any case, the driving means is not limited as long as the moving state of the zoom lens itself can be detected.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. In the second embodiment and the third embodiment, the configuration mainly considering the difference in the hardware configuration has been described, but the present invention is not limited to these. For example, the following configuration is also conceivable.

<Switching the control method suitable for the operating state>
Depending on the operating state of the imaging device or lens device (lens barrel), when focusing on the top priority regardless of the focus change even during zooming (focus tracking priority control), It is also conceivable to switch and use control that prioritizes focus continuity. For example, the drive amount is not limited in steps S1808b and S1809b in FIG. 17B, and the defocus amount detected from α in step S1805b and β in step S1806b is switched to a direction that is positively reflected. Thereby, focus tracking priority control can be realized. In addition, the drive amount is not limited in steps S2007b and S2008b in FIG. 19A, and the defocus amount detected from α in step S2005b and β in step S2006b is switched to a direction in which the defocus amount is positively reflected. Thereby, focus tracking priority control can be realized. Also, focus tracking priority control can be realized by performing zoom stop AF processing during zooming.

  As conditions for switching between these focus tracking priority control and conventional focus continuity priority control during zooming, there are the following as common conditions in the configurations of the second embodiment and the third embodiment. . For example, it is a method of switching according to the speed of the zoom lens, when the zoom speed is fast and the change in the shot image such as live view is large, the focus tracking priority control, the zoom speed is slow and the change in the shot image is slow Use focus continuity priority control. A method of switching according to the recording state of the moving image is also conceivable. For example, focus tracking priority control is used during non-recording of a moving image in which a captured image does not remain, and focus continuity priority control is used in the recording of a moving image in which a captured image remains. Furthermore, in the configuration of the second embodiment, the camera control unit 1114 grasps the cam trajectory information. Therefore, focus tracking priority control is used in areas where the cam locus information is low in density, that is, areas where the focus lens drive range is wide, and focus continuity priority control is used in areas where the density is high, ie, where the focus lens drive range is narrow. A method is conceivable. In addition, a method of switching according to the shape of the cam trajectory information is also conceivable. For example, focus tracking priority control is used in an area where the shape change is large, and focus continuity priority control is used in an area where the shape change is small.

  As described above, according to the present embodiment, the focus tracking priority control and the focus continuity priority control can be switched according to the various states of the imaging apparatus, so that appropriate control is performed according to the required focus change. It is possible to switch the method.

(Other embodiments)
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

204a Acquisition unit 204b Calculation unit 209 System control unit (determination unit)

Claims (27)

Obtaining means for obtaining a first signal and a second signal corresponding to light beams passing through different pupil regions of the imaging optical system;
A plurality of filter processes with different bands are performed on the first signal and the second signal, and a plurality of defocus amounts and a plurality of reliability are obtained based on the first signal and the second signal after the respective filter processes. A calculating means for calculating;
Determining means for determining a defocus amount used for focus adjustment from the plurality of defocus amounts based on the difference between the plurality of defocus amounts and at least one of the plurality of reliability levels; A control device characterized by.   The calculation means is configured to calculate the plurality of the first signals and the second signals after the respective filtering processes based on the degree of coincidence and the steepness of the correlation change amount between the first signals and the second signals. The control device according to claim 1, wherein the reliability is calculated.   The determining means determines a defocus amount used for focus adjustment from the plurality of defocus amounts based on the difference between the plurality of defocus amounts and the plurality of reliability levels. Item 3. The control device according to Item 1 or 2. The plurality of filtering processes include:
A first filtering process for extracting a first signal and a second signal in a first frequency band;
A second filtering process for extracting a first signal and a second signal in a second frequency band higher than the first frequency band;
The calculating means includes the plurality of defocus amounts and the plurality of reliability levels.
Based on the first signal and the second signal after the first filter processing, a first defocus amount and a first reliability are calculated,
4. The second defocus amount and the second reliability are calculated based on the first signal and the second signal after the second filter processing, according to claim 1. Control device.   The calculation unit determines the first defocus amount as a defocus amount used for the focus adjustment when a difference between the first defocus amount and the second defocus amount is larger than a first threshold. The control device according to claim 4. The calculating means includes
When the second reliability is higher than the first reliability and the second reliability is higher than a predetermined reliability threshold, the second defocus amount is used for the focus adjustment. Determined as the amount of defocus
When the second reliability is lower than the first reliability, or when the second reliability is lower than the predetermined reliability threshold, the first defocus amount is used as the defocus amount used for the focus adjustment. The control apparatus according to claim 5, wherein the control apparatus determines the focus amount. The plurality of filter processes include a third filter process for extracting a first signal and a second signal in a third frequency band higher than the second frequency band,
The calculation means calculates a third defocus amount and a third reliability as the plurality of defocus amounts and the plurality of reliability based on the first signal and the second signal after third filter processing. The control device according to claim 5, wherein the control device is a control device.   The calculation unit determines the second defocus amount as a defocus amount used for the focus adjustment when a difference between the second defocus amount and the third defocus amount is larger than a second threshold. The control device according to claim 7. The calculating means includes
When the third reliability is higher than the second reliability and each of the second reliability and the third reliability is higher than a predetermined reliability threshold, the third defocus is performed. Determining the amount as the defocus amount used for the focus adjustment;
When the third reliability is lower than the second reliability, or when the second reliability or the third reliability is lower than the predetermined reliability threshold, the second defocus amount is set to The control device according to claim 8, wherein the control device is determined as a defocus amount used for focus adjustment.   The control device according to claim 8, wherein the second threshold value is smaller than the first threshold value.   The control device according to any one of claims 8 to 10, wherein the first threshold value and the second threshold value are larger than a depth of focus. An imaging device having a first photoelectric conversion unit and a second photoelectric conversion unit that receive light beams passing through different pupil regions of the imaging optical system;
Obtaining means for obtaining a first signal and a second signal respectively corresponding to output signals from the first photoelectric conversion unit and the second photoelectric conversion unit;
A plurality of filter processes with different bands are performed on the first signal and the second signal, and a plurality of defocus amounts and a plurality of reliability are obtained based on the first signal and the second signal after the respective filter processes. A calculating means for calculating;
Determining means for determining a defocus amount used for focus adjustment from the plurality of defocus amounts based on the difference between the plurality of defocus amounts and at least one of the plurality of reliability levels; An imaging apparatus characterized by the above.   The image pickup device includes the first photoelectric conversion unit and the second photoelectric conversion unit with respect to one microlens, and the microlens is two-dimensionally arranged. The imaging device described. Obtaining a first signal and a second signal corresponding to light beams passing through different pupil regions of the imaging optical system;
A plurality of filter processes with different bands are performed on the first signal and the second signal, and a plurality of defocus amounts and a plurality of reliability are obtained based on the first signal and the second signal after the respective filter processes. A calculating step;
Determining a defocus amount used for focus adjustment from the plurality of defocus amounts based on the difference between the plurality of defocus amounts and at least one of the plurality of reliability levels. Characteristic control method. Obtaining a first signal and a second signal corresponding to light beams passing through different pupil regions of the imaging optical system;
A plurality of filter processes with different bands are performed on the first signal and the second signal, and a plurality of defocus amounts and a plurality of reliability are obtained based on the first signal and the second signal after the respective filter processes. A calculating step;
Determining a defocus amount used for focus adjustment from the plurality of defocus amounts based on the difference between the plurality of defocus amounts and at least one of the plurality of reliability levels; A program characterized by letting   A storage medium storing the program according to claim 15. Obtaining means for obtaining a first signal and a second signal corresponding to light beams passing through different pupil regions of the imaging optical system;
Calculating means for calculating a defocus amount and reliability based on the first signal and the second signal;
Focus control means for controlling a focus lens according to the defocus amount and the reliability,
The control device, wherein the focus control unit limits a drive range of the focus lens according to the defocus amount and the reliability during driving of the zoom lens.   When the focus control unit determines that the amount of movement of the focus lens is greater than a predetermined amount during driving of the zoom lens, the focus lens is configured so that the amount of movement of the focus lens does not exceed the predetermined amount. The control device according to claim 17, wherein the target position is corrected. Obtaining means for obtaining a first signal and a second signal corresponding to light beams passing through different pupil regions of the imaging optical system;
Calculating means for calculating a defocus amount and reliability based on the first signal and the second signal;
Focus control means for controlling a focus lens according to the defocus amount and the reliability,
The focus control means includes a first mode for performing focus control over the entire movable range of the focus lens, and a second mode for performing focus control within a predetermined range based on a focus lens position set by a user. And changing the control according to the defocus amount and the reliability.   20. The focus control unit according to claim 19, wherein the focus control unit changes a frame addition condition according to the defocus amount and the reliability in the first mode and the second mode. Control device.   The focus control unit changes the number of times the focus lens is driven in accordance with the defocus amount and the reliability in the first mode and the second mode. The control device described.   The control apparatus according to claim 21, wherein the focus control unit makes the number of times of driving the focus lens in the second mode smaller than the number of times of driving of the focus lens in the first mode.   In the second mode, when the reliability is higher than a first reliability threshold and the defocus amount is larger than a first defocus amount threshold, the focus control unit The control device according to any one of claims 19 to 22, wherein control is not performed.   The focus control unit controls the focus lens based on an addition average of defocus amounts of a plurality of frames when the defocus amount and the reliability satisfy the condition of frame addition. Item 20. The control device according to Item 20. The frame addition condition is that the reliability is lower than the first reliability threshold and higher than the second reliability threshold, and the defocus amount is higher than the second defocus amount threshold. Is also a small case,
25. The focus control unit according to claim 24, wherein the second defocus amount threshold value in the second mode is larger than the second defocus amount threshold value in the first mode. Control device.   26. The control device according to claim 25, wherein the focus control unit does not perform the control in the second mode when the reliability is lower than the second reliability threshold. The calculating means performs a plurality of filter processes with different bands on the first signal and the second signal, and calculates a plurality of defocus amounts based on the first signal and the second signal after the respective filter processes. Calculate
The focus control unit controls the focus lens based on a defocus amount in a highest band among the plurality of defocus amounts calculated by the calculation unit in the second mode. Item 27. The control device according to any one of Items 19 to 26.