JP2017187726A - Imaging apparatus and method for driving imaging element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the decrease of focus detection performance, when an area where focus detection is possible is limited in an imaging area.SOLUTION: An imaging apparatus includes: an imaging element which can switch first read-out control for reading out a signal so as to obtain a pair of focus detection signals and second read-out control for adding an electric charge for each pixel and reading out an addition signal, to perform read-out; setting means which sets a row read out by the first read-out control among the plurality of rows of a plurality of photoelectric conversion parts including a focus detection area; and focus detection means which performs the detection of a focus state by a phase difference system by using the pair of focus detection signals obtained from a partial range of the row read out by the first read-out control. When the reliability of the focus state detected by first focus detection means is lower than a first threshold, the setting means changes the row read out by the first read-out control to the row not read out by the first read-out control.SELECTED DRAWING: Figure 10

Description

  The present invention relates to an imaging apparatus and an imaging element driving method, and more particularly to an imaging apparatus that performs focus detection using an image signal obtained from an imaging element and an imaging element driving method.

  As one of focus detection methods performed in the imaging apparatus, there is an imaging plane phase difference method in which focus detection by a phase difference method is performed by focus detection pixels formed on an image sensor. In focus detection using the imaging surface phase difference method, it is possible to detect the defocus direction and the defocus amount at the same time by using focus detection pixels formed on the image sensor. Accordingly, the focus adjustment can be performed at a higher speed than the so-called contrast method in which focus detection is performed based on the contrast state of the image signal. Unlike the case where a focus detection sensor is used in addition to the image sensor, the imaging and focus detection optical systems are the same, so there is no influence of parallax, and the imaging device is compact. It also leads to

  Conventionally, a method of discretely arranging focus detection pixels between imaging pixels has been proposed, but there are the following problems. First, since a region where focus detection is possible with respect to the imaging region is limited to a fixed position, setting of the focus detection region can be restricted. Further, the focus detection pixel is treated as a defective pixel when an image is obtained, and the output signal of the focus detection pixel needs to be interpolated with the output signal of the surrounding imaging pixels, so that the image quality is deteriorated. Therefore, in Patent Documents 1 and 2, all the pixels on the image sensor are formed using two or more independently readable photodiodes, and one pixel has both an imaging function and a focus detection function. Thus, a method of performing focus detection simultaneously with readout for imaging has been proposed.

JP 2001-250931 A Japanese Unexamined Patent Publication No. 2015-43026

  However, in both methods of Patent Document 1 and Patent Document 2, the resolution is increased as in recent 4K and 8K cameras, and the frame rate is increased as in a high-speed camera capable of high-speed shooting. As a result, the following problems occurred. In other words, the number of focus detection pixels that can be read out in a predetermined time is limited, and the phase difference calculation processing time that is performed using the read focus detection signal is also limited. There has been a restriction that focus detection can be performed only in a certain area.

  In a general camera, the focus detection frame is set at a predetermined ratio with respect to the imaging area. However, depending on the size of the focus detection frame set by the above-mentioned restrictions, focus detection is performed within the focus detection frame. There is an area that cannot be used. In this case, for example, if there is a subject in an area where focus detection is not possible even if the subject exists within the focus detection frame, the correct focus detection result (defocus direction and defocus amount) cannot be obtained, and the intended focus adjustment is performed. There is a problem that can not be. In addition, when there is a subject in a region where focus detection cannot be performed, if the lens is moved continuously or stopped, there is a problem that the quality of the moving image is deteriorated.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to reduce a decrease in focus detection performance when a region where focus detection is possible is limited.

  In order to achieve the above object, an imaging apparatus of the present invention has a plurality of photoelectric conversion units for each of a plurality of microlenses arranged in a matrix, and a pair of focus detections from the plurality of photoelectric conversion units. A first readout control for reading out the signal so as to obtain a signal, and a second readout control for reading out the added signal by adding the charges accumulated in the plurality of photoelectric conversion units corresponding to each microlens, An image sensor that can be switched and read, and a setting unit that sets a row to be read by the first read control among a plurality of rows to be read by the second read control including a predetermined first focus detection region. First focus detection for detecting a focus state by a phase difference method using a pair of focus detection signals obtained from a part of the rows read by the first read control. A means, wherein the setting means, based on a predetermined condition, changes the setting of the row reading by said first reading control.

  According to the present invention, it is possible to reduce a decrease in focus detection performance when a region where focus detection is possible is limited in the imaging region.

1 is a schematic configuration diagram of an imaging apparatus according to an embodiment of the present invention. Schematic of the pixel arrangement | sequence of the image pick-up element in embodiment. FIG. 2 is a schematic plan view and a schematic cross-sectional view of a pixel in an embodiment. Schematic explanatory drawing of the pixel structure and pupil division in the embodiment. FIG. 2 is a schematic explanatory diagram of pupil division in an imaging optical system and an imaging element in an embodiment. FIG. 6 is a schematic relationship diagram between a defocus amount and an image shift amount of a first focus detection signal and a second focus detection signal in the embodiment. 5 is a flowchart illustrating focus detection processing using an imaging surface phase difference method according to the first embodiment. 5 is a flowchart illustrating focus detection area setting processing according to the first embodiment. The figure for demonstrating the subject of the focus detection process by the conventional imaging surface phase difference system. FIG. 5 is a diagram illustrating an example of setting a focus detection area in the first embodiment. The figure for demonstrating contrast AF control during arrangement | positioning change of the focus detection area | region in 1st Embodiment. 9 is a flowchart illustrating focus detection processing by a contrast method according to the second embodiment. 10 is a flowchart illustrating focus detection area setting processing according to the second embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. However, the dimensions, shapes, relative arrangements, and the like of the components exemplified in the present embodiment should be changed as appropriate according to the configuration of the apparatus to which the present invention is applied and various conditions. It is not limited to.

Overall Configuration FIG. 1 shows a configuration of a video camera (imaging device) including a focus adjustment device in the present embodiment. In this embodiment, as will be described later, based on a signal having a phase difference obtained from the image sensor, the focus detection region is changed according to the focus detection result of the imaging surface phase difference method, and the focus adjustment operation is performed. A video camera to be performed will be described. Note that the imaging apparatus according to the present embodiment may be any electronic device having a camera function such as a mobile phone with a camera function, a computer with a camera, as well as a camera such as a digital camera or a digital video camera.

  In FIG. 1, the first fixed lens 101, the variable magnification lens 102, the diaphragm 103, the second fixed lens 104, and the focus compensator lens 105 constitute an imaging optical system for imaging light from a subject. The variable power lens 102 moves in the optical axis direction and performs a variable power operation. A focus compensator lens (hereinafter referred to as a focus lens) 105 has both a function of correcting the movement of the focal plane accompanying zooming and a focus adjustment function.

  The focusing drive unit 111 is a drive unit for moving the focus lens 105 in the optical axis direction for focus adjustment, and includes an actuator such as a stepping motor, a DC motor, a vibration motor, and a voice coil motor.

  The image sensor 106 includes a photoelectric conversion element such as a CCD sensor or a CMOS sensor, and a peripheral portion. The image sensor 106 photoelectrically converts an object image formed by forming an image of light that has passed through the image pickup optical system to generate an electrical signal. Output. Although details will be described later, the image sensor 106 of the present embodiment includes two photoelectric conversion units for each of a plurality of microlenses arranged in two dimensions. Then, a reading method (first reading method) for reading out a pair of focus detection signals corresponding to each of the two photoelectric conversion units (a first reading method) and a reading method for reading out only a pixel signal obtained by adding the outputs of the two photoelectric conversion units ( It can be driven by the second reading method.

  The phase difference AF pixel readout setting unit 117 sets a pixel group (or line) to be read out by the first readout method in units of rows among all the pixels of the image sensor 106. As a result, it is possible to arbitrarily specify which region of the imaging region (all pixels of the image sensor 106) is read for phase difference AF.

  The CDS / AGC circuit 107 samples the output of the image sensor 106 and adjusts the gain. The camera signal processing circuit 108 performs various kinds of image processing on the output signal from the CDS / AGC circuit 107 to generate an image signal. The monitor 109 is configured by an LCD or the like, and in addition to the image signal from the camera signal processing circuit 108, information on the shooting mode of the imaging apparatus, a focus detection frame (AF frame) that serves as a guide for the set focus detection area, and the like. Displays various information. The recording device 110 records the image signal from the camera signal processing circuit 108 on a recording medium such as a magnetic tape, an optical disk, or a semiconductor memory.

  The phase difference AF gate 112 passes a focus detection signal corresponding to a plurality of focus detection areas, which will be described later, out of the image signal processed by the CDS / AGC circuit 107 and read by the first reading method. The phase difference AF signal processing unit 113 performs correlation calculation based on the pair of focus detection signals that have passed through the phase difference AF gate 112, and the image shift amount and reliability information (two-image coincidence degree) for each focus detection region. 2 image steepness, contrast information, saturation information, scratch information, etc.). Then, the calculated image shift amount and reliability information are output to the camera microcomputer 114. The camera microcomputer 114 calculates the current focal position on the imaging surface and the in-focus position from the image shift amount calculated by the phase difference AF signal processing unit 113 based on a phase difference type focus detection method described later. A deviation amount, a so-called defocus amount is calculated. Further, the camera microcomputer 114 converts the calculated defocus amount into a drive amount of the focus lens 105, and controls the focusing drive unit 111 to drive the focus lens 105. Hereinafter, the above-described AF control of the imaging surface phase difference method is referred to as “phase difference AF”.

  The contrast AF gate 115 outputs only the signal in the region (contrast AF region) used for focus detection by contrast AF among the output signals of all pixels from the CDS / AGC circuit 107, and the contrast AF signal processing unit 116 in the subsequent stage. To supply. The contrast AF area will be described later.

  The contrast AF signal processing unit 116 extracts, for example, a component of a predetermined frequency band by applying a filter to the image signal in the contrast AF area supplied from the contrast AF gate 115, and obtains a contrast AF evaluation value. Generate. What is extracted is, for example, a high-frequency component of the signal that has passed through the contrast AF gate 115, a difference (luminance difference component) between the maximum value and the minimum value of the luminance level, and the like. The contrast AF evaluation value is a value representing the sharpness (degree of contrast) of the video generated based on the output signal from the image sensor 106, but the sharpness of the focused video is high, and the blurred video Since the sharpness is low, it can be used as a value representing the focus state of the imaging optical system. The generated contrast AF evaluation value is output to the camera microcomputer 114.

  The camera microcomputer 114 drives the focus lens 105 by controlling the focusing drive unit 111 based on the contrast AF evaluation value given from the contrast AF signal processing unit 116. Hereinafter, the contrast AF control described above is referred to as “contrast AF”.

Image Sensor FIG. 2 is a diagram showing an outline of the pixel array of the image sensor 106 in the present embodiment. FIG. 2 shows a pixel array of a two-dimensional CMOS sensor used as the image sensor 106 in the present embodiment in a range of 4 columns × 4 rows of imaging pixels (a range of 8 columns × 4 rows as an array of focus detection pixels). It is shown by.

  In the present embodiment, the pixel group 200 includes pixels of 2 columns × 2 rows. In each pixel group 200, a pixel 200R having an R (red) spectral sensitivity is located at the upper left position, a pixel 200G having a G (green) spectral sensitivity is located at the upper right and lower left positions, and a B (blue) spectrum. A pixel 200B having sensitivity is arranged at a lower right position. Further, each pixel includes a first focus detection pixel 201 and a second focus detection pixel 202 arranged in 2 columns × 1 row for each of a plurality of microlenses arranged in a matrix. The image sensor 106 arranges a large number of pixel groups 200 made up of 4 columns × 4 rows of imaging pixels (8 columns × 4 rows of focus detection pixels) shown in FIG. 2 on the imaging surface, and acquires pixel signals and focus detection signals. Is possible.

  2A is a plan view of one pixel 200G of the image sensor 106 shown in FIG. 2 as viewed from the light receiving surface side (+ z side) of the image sensor 106, and FIG. 3A is a cross-sectional view taken along line aa. A cross-sectional view seen from the −y side is shown in FIG. As shown in FIG. 3, in the pixel 200G of the present embodiment, a microlens 305 for condensing incident light is formed on the light receiving surface side of each pixel, and NH division (two divisions) is performed in the x direction, and in the y direction. The photoelectric conversion units 301 and 302 that are divided into NVs (one division) are formed. The photoelectric conversion units 301 and 302 correspond to the first focus detection pixel 201 and the second focus detection pixel 202, respectively. In each pixel, a color filter 306 is formed between the microlens 305 and the photoelectric conversion units 301 and 302. Further, as necessary, the spectral transmittance of the color filter may be changed for each focus detection pixel, or the color filter may be omitted.

  Light incident on the pixel 200 </ b> G illustrated in FIG. 3 is collected by the microlens 305, dispersed by the color filter 306, and then received by the photoelectric conversion units 301 and 302. In the photoelectric conversion units 301 and 302, a pair of electrons and holes are generated by photoelectric conversion according to the amount of received light and separated by a depletion layer, and then negatively charged electrons are accumulated in an n-type layer (not shown). On the other hand, the holes are discharged to the outside of the image sensor 106 through a p-type layer connected to a constant voltage source (not shown). Electrons accumulated in the n-type layers (not shown) of the photoelectric conversion units 301 and 302 are transferred to a capacitance unit (FD) (not shown) via a transfer gate, converted into a voltage signal, and output. The

  The correspondence relationship between the pixel structure of this embodiment shown in FIG. 3 and pupil division will be described with reference to FIG. FIG. 4 is a cross-sectional view of the pixel structure of the first embodiment shown in FIG. 3A as viewed from the + y side and a view showing an exit pupil plane of the imaging optical system. In FIG. 4, the x-axis and y-axis of the cross-sectional view are inverted with respect to FIG. 3 in order to correspond to the coordinate axis of the exit pupil plane. In FIG. 4, the same parts as those in FIG. 3 are denoted by the same reference numerals.

  As shown in FIG. 4, the first pupil partial region 401 of the first focus detection pixel 201 is substantially conjugate with the light receiving surface of the photoelectric conversion unit 301 whose center of gravity is decentered in the −x direction and the microlens 305. This represents a pupil region that can be received by the first focus detection pixel 201. In the first pupil partial region 401 of the first focus detection pixel 201, the center of gravity is decentered on the + X side on the pupil plane. In addition, the second pupil partial region 402 of the second focus detection pixel 202 is substantially conjugated with the light receiving surface of the photoelectric conversion unit 302 whose center of gravity is decentered in the + x direction and the microlens 305. A pupil region that can be received by the focus detection pixel 202 is shown. The center of gravity of the second pupil partial region 402 of the second focus detection pixel 202 is eccentric to the −X side on the pupil plane. The pupil region 400 is a pupil region that can receive light in the entire pixel 200G when the photoelectric conversion unit 301 and the photoelectric conversion unit 302 (first focus detection pixel 201 and second focus detection pixel 202) are combined.

  FIG. 5 shows an outline of the correspondence between the image sensor 106 of this embodiment and pupil division by the microlens 305. Light beams that have passed through different pupil partial regions of the first pupil partial region 401 and the second pupil partial region 402 of the exit pupil 410 are incident on each pixel of the image sensor 106 at different angles and are divided into 2 × 1. The first focus detection pixel 201 and the second focus detection pixel 202 receive light. In the present embodiment, an example is shown in which the pupil region is divided into two pupils in the horizontal direction, but pupil division may be performed in the vertical direction as necessary.

  In the imaging device 106 of the present embodiment, each imaging pixel includes the first focus detection pixel 201 and the second focus detection pixel 202, but the present invention is not limited to this. If necessary, an imaging pixel that receives a light beam that has passed through a pupil region that is a combination of the first pupil partial region 401 and the second pupil partial region 402 of the imaging optical system, and the first focus detection pixel 201 and the second focus detection pixel 201. The focus detection pixel 202 may have an individual pixel configuration. In that case, the first focus detection pixel and the second focus detection pixel may be partially arranged in a part of the arrangement of the imaging pixels.

  The first focus detection signal 201 is collected by collecting the light reception signals of the first focus detection pixels 201 of the respective pixels of the image sensor 106 having the above-described configuration, and the light reception signals of the second focus detection pixels 202 of the respective pixels are collected. A focus detection signal is generated to perform focus detection. Further, an image signal (addition signal) can be generated by adding the light reception signals of the first focus detection pixel 201 and the second focus detection pixel 202 for each pixel corresponding to each microlens of the image sensor 106. .

Next, the relationship between the defocus amount and the image shift amount of the first focus detection signal and the second focus detection signal acquired by the image sensor 106 of the present embodiment will be described. FIG. 6 is a diagram illustrating the relationship between the defocus amounts of the first focus detection signal and the second focus detection signal and the image shift amount between the first focus detection signal and the second focus detection signal. The imaging device 106 of the present embodiment is disposed on the imaging surface 500, and the exit pupil 410 of the imaging optical system is divided into two in the first pupil partial region 401 and the second pupil partial region 402, as in FIGS. Divided. In FIG. 6, the same parts as those in FIGS.

  The defocus amount d is negative (d <0) when the distance from the imaging position of the subject to the imaging surface 500 is a magnitude | d |, where the imaging position of the subject is closer to the subject than the imaging surface. ), The rear pin state on the opposite side of the subject from the imaging surface 500 is defined as positive (d> 0). The focus state where the imaging position of the subject is on the imaging surface 500 (focus position) is d = 0. In FIG. 6, the subject 601 shows an example in a focused state (d = 0), and the subject 602 shows an example in a front pin state (d <0). The front pin state (d <0) and the rear pin state (d> 0) are collectively referred to as a defocus state (| d |> 0).

  In the front pin state (d <0), the subject light that has passed through the first pupil partial region 401 out of the luminous flux from the subject 602 is once condensed and then has a width Γ1 with the center of gravity G1 of the luminous flux as the center. The image spreads and becomes a blurred image on the imaging surface 500. The same applies to the subject light that has passed through the second pupil partial region 402, and a blurred image having a width Γ2 around the center of gravity position G2 is formed. The blurred image is received by the first focus detection pixel 201 and the second focus detection pixel 202 constituting each pixel arranged in the image sensor 106, and a first focus detection signal and a second focus detection signal are generated. Therefore, the first focus detection signal and the second focus detection signal are recorded as subject images in which the subject 602 is blurred in the widths Γ1 and Γ2 at the gravity center positions G1 and G2 on the imaging surface 500. The blur widths Γ1 and Γ2 of the subject image generally increase in proportion as the magnitude | d | of the defocus amount d increases. Similarly, the magnitude | p | of the object image displacement amount p (= difference G1-G2 in the center of gravity of the light beam) between the first focus detection signal and the second focus detection signal is also the size of the defocus amount d. As | d | increases, it generally increases in proportion. Even in the rear pin state (d> 0), the image shift direction of the subject image between the first focus detection signal and the second focus detection signal is opposite to that in the front pin state, but the same.

  Thus, as the magnitude of the defocus amount of the first focus detection signal and the second focus detection signal or the imaging signal obtained by adding the first focus detection signal and the second focus detection signal increases, The amount of image shift between the first focus detection signal and the second focus detection signal increases.

Focus Detection In this embodiment, phase difference AF is performed using the relationship between the image shift amount and the defocus amount of the first focus detection signal and the second focus detection signal described above. In the phase difference AF, the first focus detection signal and the second focus detection signal are relatively shifted to calculate the correlation amount indicating the degree of coincidence of the signals, and the image shift from the shift amount that improves the correlation (signal coincidence). Detect the amount. As the magnitude of the defocus amount of the image signal increases, the amount of image shift between the first focus detection signal and the second focus detection signal increases. The focus is detected by converting to.

<First Embodiment>
Hereinafter, a first embodiment of the present invention using the imaging apparatus having the above configuration will be described.

[Issue of phase difference method on imaging surface]
Here, the problem of the imaging plane phase difference method in the first embodiment will be described with reference to FIG. FIG. 9A shows the relationship between the display AF frame 92 for the imaging region 91 and the regions 93 a to 93 d read by the first readout method set by the phase difference AF pixel readout setting unit 117. The focus detection signal is read out with one horizontal pixel line as a minimum unit. However, in the following, each of the regions 93a to 93d is detected as a focus detection signal that is added in the vertical direction to improve S / N. Called the line.

  As described above, as the resolution is increased and the frame rate is increased as in 4K and 8K cameras, the number of focus detection lines that can be read out in a predetermined time is limited. This is because the following readout control is generally performed in the first readout method for obtaining a pair of focus detection signals. That is, first, only one of the first focus detection pixel 201 and the second focus detection pixel 202 is read for focus detection. Subsequently, addition reading of the first focus detection pixel 201 and the second focus detection pixel 202 is performed for the captured image, or only the other of the first focus detection pixel 201 and the second focus detection pixel 202 is read. As described above, since it is necessary to read twice for one line, it takes time to read, and the number of focus detection lines that can be read within one frame period can be limited. When addition reading is performed, the second focus detection signal is based on the difference between the signal obtained by adding and reading the first focus detection pixel 201 and the second focus detection pixel 202 and the read signal of only the first focus detection pixel 201. calculate. Further, when signals are read from the first focus detection pixel 201 and the second focus detection pixel 202, the read signals are added for each pixel corresponding to each microlens to obtain a signal for a captured image.

  On the other hand, the correlation calculation in the phase difference AF signal processing unit 113 and the calculation processing of the defocus amount in the camera microcomputer 114 must be performed for each line, and must be performed for all focus detection lines. Therefore, even if the first and second focus detection signals can be read from all the pixels of the image sensor 106, the number of focus detection lines that can be processed within one frame period is limited.

  FIG. 9B shows the arrangement of the focus detection lines 93a to 93d when the display AF frame 92 is set large. As described above, since there is a limit to the number of focus detection lines that can be read and processed in one frame period, when the display AF frame 92 is enlarged, the focus detection lines 93a to 93d are spaced apart. However, for example, when the subject 94 is between the focus detection lines, correct focus detection cannot be performed.

[Focus detection area determination method]
A focus detection area setting process in the imaging surface phase difference method of the first embodiment will be described. First, the detection area flag used in the following description will be described with reference to FIG.

  The detection area flag has four types of states according to the setting state of the focus detection area, and a flag value is assigned to each state. The relationship between the four types of states and the numerical values of the flags is 1: normal state, 2: enlarged state, 3: during rearrangement, and 4: rearranged state. Hereinafter, each state will be described with reference to FIG. In FIG. 10, the same components as those in FIG. 9 are denoted by the same reference numerals.

  “1: Normal state” represents a state in which the focus detection area is set with a predetermined size with respect to the display AF frame 92 as shown in FIG. As described with reference to FIG. 9B, since the number of focus detection lines is limited, the setting is discrete so that the focus detection lines are evenly arranged in the entire display AF frame 92. The focus detection areas 95a to 95d perform correlation calculation in the phase difference AF signal processing unit 113 and defocus amount calculation processing in the camera microcomputer 114 among focus detection signals read from the focus detection lines 93a to 93d. The range is shown. Therefore, the phase difference AF gate 112 passes signals output from the pixels corresponding to the focus detection areas 95a to 95d. In the first embodiment, the focus detection areas 95 a to 95 d are set by the phase difference AF signal processing unit 113 or the camera microcomputer 114. In general, in AF control, there is a problem that the background or the like is focused on a subject whose distance is competing, and therefore it is preferable that the focus detection area is small. Therefore, in the first embodiment, as a normal state, the focus detection areas 95a to 95d are described as being set short in the horizontal direction with respect to the display AF frame 92. However, the present invention is not limited to this, and the same length as the display AF frame is used. You may set it.

  “2: Enlarged state”, as shown in FIG. 10B, is a state in which areas larger than “1: normal state” with respect to the display AF frame 92 are set as focus detection areas 95a ′ to 95d ′. Represent. In the first embodiment, as shown in the drawing, a state where the focus detection areas 95a to 95d in the “1: normal state” are expanded in the horizontal direction is referred to as “2: enlarged state”. In focus detection by the phase difference method, when a large defocus state (large blur state) is reached, the steepness of the first and second focus detection signals becomes gentle. For this reason, if the shift amount in the shift processing for relatively shifting the first and second focus detection signals in the pupil division direction in the correlation calculation is small, it becomes difficult to correlate the two focus detection signals. The amount of focus cannot be calculated. Therefore, particularly in the case of large blurring, it is possible to obtain the defocus amount more accurately by enlarging the focus detection area in the pupil division direction (horizontal direction in the first embodiment) and increasing the shift amount. It becomes. Even when a subject is present outside the focus detection area in the display AF frame 92, the influence of the subject missing can be reduced by enlarging the subject in the horizontal direction.

  “3: During the rearrangement period” means, as shown in FIG. 10C, focus detection areas 95e to 95g in areas different from the focus detection areas set in FIGS. 10A and 10B. Is set, but the defocus detection result has not been output yet.

  “4: rearranged state” represents a state in which defocus detection results are output in the reset focus detection areas 95e to 95g. This is a feature of the first embodiment. When the subject 94 enters the gap in the focus detection area as shown in FIGS. 10A and 10B, the defocus amount is correctly set. I can't get it. Therefore, as shown in FIG. 10C, the focus detection areas 95e to 95g are rearranged so as to fill the gaps between the set focus detection areas 95a ′ to 95d ′, and the new focus detection areas 95e to 95g By performing the focus calculation, the above problem is reduced.

  Note that the reason for distinguishing between “3: during the rearrangement period” and “4: rearranged state” is that the correlation amount calculation and the deduplication are performed until the defocus detection result is output after the focus detection area is reset. This is to determine a state waiting for output as a result of the focus calculation process.

  In the first embodiment, when the focus detection area is changed from the normal state to the enlarged state (enlarged in the horizontal direction), the result output is not waited, but the enlarged state is rearranged (rearranged in the vertical direction). If so, wait for the result output. However, it may be configured to wait even when enlarged in the horizontal direction.

  Next, with reference to FIG. 7, the imaging surface phase difference type focus detection processing in the first embodiment will be described. 7 is executed by the image sensor 106, the phase difference AF signal processing unit 113, and the camera microcomputer 114 that controls them, and may operate in combination with the processing of FIG. 8 described later and the operation cycle. Alternatively, it may be operated independently at a fast cycle.

  In S101, the phase difference AF signal processing unit 113 acquires first and second focus detection signals used for the phase difference AF. More specifically, among the first and second focus detection signals read from the focus detection line set as described later by the phase difference AF pixel readout setting unit 117, the phase difference AF gate 112 is set. First and second focus detection signals of the focus detection area that has passed are acquired.

  In S102, the phase difference AF signal processing unit 113 performs pixel addition processing in the column direction on each of the first focus detection signal and the second focus detection signal, and performs processing for improving the S / N ratio of the signal, Further, a Bayer (RGB) addition process is performed to convert the RGB signal into a luminance Y signal. These two addition processes are collectively referred to as a pixel addition process.

  In S103, filter processing is performed on the first focus detection signal and the second focus detection signal (luminance Y signal) that have been subjected to pixel addition processing. For example, when focus detection is performed in a large defocus state, it is necessary to configure the pass band of the filter process to include a low frequency band. If necessary, when performing focus adjustment from the large defocus state to the small defocus state, the pass band of the filter processing may be adjusted according to the defocus state.

In S104, a shift process for relatively shifting the first focus detection signal and the second focus detection signal (luminance Y signal) after the filter process in the pupil division direction is performed, and a correlation amount representing the degree of coincidence of the signals is calculated. Perform correlation calculation. In this correlation calculation, the filtered k-th first focus detection signal is A (k), the second focus detection signal is B (k), and the range of number k corresponding to the focus detection area is W. Further, s ₁ the shift amount in the shift _processing, when the shift range of the shift amount s ₁ and .GAMMA.1, correlation amounts (first evaluation value) COR is calculated by the equation (1).

シフト量ｓ_１のシフト処理により、ｋ番目の第１焦点検出信号Ａ（ｋ）とｋ−ｓ_１番目の第２焦点検出信号Ｂ（ｋ−ｓ_１）を対応させて減算し、シフト減算信号を生成する。そして、生成されたシフト減算信号の絶対値を計算し、焦点検出領域に対応する範囲Ｗ内で番号ｋの和を取り、相関量ＣＯＲ（ｓ_１）を算出する。必要に応じて、各行毎に算出された相関量を、各シフト量毎に、複数行に亘って加算しても良い。

By the shift process of the shift amount s ₁ , the k-th first focus detection signal A (k) and the k-s _first focus detection signal B (k-s ₁ ) are subtracted in correspondence with each other, and the shift-subtract signal Is generated. Then, the absolute value of the generated shift subtraction signal is calculated, the number k is summed within the range W corresponding to the focus detection area, and the correlation amount COR (s ₁ ) is calculated. If necessary, the correlation amount calculated for each row may be added over a plurality of rows for each shift amount.

  In S105, a real value shift amount at which the correlation amount is the minimum value is calculated from the correlation amount by sub-pixel calculation, and is set as an image shift amount p1. The defocus amount (Def) is calculated by multiplying the image shift amount p1 by the image height of the focus detection area, the F value of the imaging lens (imaging optical system), and the first conversion coefficient K1 corresponding to the exit pupil distance. .

  In S106, a reliability representing how reliable the defocus amount and defocus direction calculated in S105 is calculated. The correlation calculation and the calculation of the defocus amount are performed for each focus detection area, and the process ends after being performed in all focus detection areas.

  Next, the focus detection area setting process using the above-described detection area flag will be described with reference to FIG.

  First, in S201, the camera microcomputer 114 determines a scene change of the camera. If it is determined that there is a scene change, the process proceeds to S202, and if it is determined that there is no scene change, the process proceeds to S204. Specifically, in S201, it is determined whether the state has changed, such as whether panning has been performed or whether the shooting mode has been changed.

  Next, in S202, the focus detection areas are set to focus detection areas 95a to 95d shown in FIG. 10A, and in S203, the detection area flag is set to “1: normal state”, and then the process proceeds to S204.

  In S204, the camera microcomputer 114 determines whether or not the detection area flag is “3: during the rearrangement period” indicating that the focus detection area is in the rearrangement period. If the detection area flag is “3: during the rearrangement period”, the process proceeds to S205. If the detection area flag is not “3: during the rearrangement period”, the process proceeds to S210.

  Next, in S205, the camera microcomputer 114 determines whether or not the defocus detection result is output in the focus detection areas 95e to 95g after the rearrangement as described above with reference to FIG. If it has been output, the process proceeds to S207, and if it has not been output, the process proceeds to S206.

  In S206, the camera microcomputer 114 compares the contrast AF evaluation value output through the contrast AF gate 115 and the contrast AF signal processing unit 116 with the previously output contrast AF evaluation value, and the change amount is the first. It is determined whether it is within the threshold.

  Here, the process performed in S206 will be described in detail. The camera microcomputer 114 receives the contrast AF evaluation value at a timing (hereinafter referred to as “contrast AF evaluation value output timing”) depending on the operation cycle (frame rate or shutter speed) of the camera. The received contrast AF evaluation value is stored as a history in a RAM (not shown) in the camera microcomputer 114. The camera microcomputer 114 compares the received latest contrast AF evaluation value with the past contrast AF evaluation value stored in the RAM. As a result of the comparison, if “the latest contrast AF evaluation value−the past contrast AF evaluation value> 0”, it is determined that “the amount of change is within the first threshold”.

  Further, a condition is further added so that “first threshold> latest contrast AF evaluation value−past contrast AF evaluation value> 0”, and only when there is a change in contrast AF evaluation value within the first threshold, “change amount” May be within the first threshold ”.

  The “past contrast AF evaluation value” described above may be the contrast AF evaluation value output at the previous contrast AF evaluation value output timing, or the contrast AF output at the contrast AF evaluation value output timing a predetermined number of times ago. It may be an evaluation value. Furthermore, a contrast AF evaluation value processed by adding, averaging, weighting addition, etc. a plurality of past contrast AF evaluation values may be used.

  In S206, if the amount of change is within the first threshold, the process proceeds to S209, and if the amount of change exceeds the first threshold, the process proceeds to S208.

  In step S209, the focus lens 105 is driven using a highly reliable defocus amount that was output before rearranging the focus detection area. Specifically, in S209, the defocus amount (Def_bk) backed up in S211 described later is substituted for the defocus amount Def used to drive the focus lens 105, and the process proceeds to S220.

  On the other hand, in S208, the camera microcomputer 114 sends an instruction to stop the focus lens 105 to the focusing drive unit 111, and the process is terminated.

  Here, an example of a state in which the determination of S206 and the processing of S208 and S209 are performed will be described with reference to FIG. FIG. 11 shows the contrast AF evaluation value when the defocus amount by the imaging surface phase difference method cannot be detected in the state where AF control is performed in “2: Enlarged state” and becomes “3: During rearrangement period”. It is a figure which shows the change of. The horizontal axis represents the lens position of the focus lens 105, and the vertical axis represents the contrast AF evaluation value. Also, the x mark in the figure represents the contrast AF evaluation value output at each lens position, and the x mark is connected by a line to virtually express the contrast AF evaluation value between x and x. In this description, it is assumed that the focus lens 105 is driven at a constant speed, so that the horizontal axis represents the lens position and at the same time, so the lens position and time are represented here. Treat with almost equivalent meaning.

  FIG. 11A is a diagram illustrating a case where the change in the contrast AF evaluation value is within the first threshold during “3: during the rearrangement period”. First, the focus lens 105 is driven based on the defocus amount detected at the lens position P1 in “2: enlarged state”. While the lens is being driven, the focus lens 105 is continuously driven in the in-focus direction (right direction in FIG. 11A) while detecting the defocus amount by the above-described imaging surface phase difference type focus detection at a predetermined interval. . In the first embodiment, while driving the lens, the contrast AF evaluation value is periodically acquired at the above-described contrast AF evaluation value acquisition timing, and the contrast AF evaluation value is stored while being associated with the lens position. Here, since the defocus amount is obtained, the focus lens 105 is driven based on the defocus amount without using the contrast AF evaluation value basically.

  Next, it is assumed that the reliability of the defocus amount is determined to be equal to or less than the second threshold at the lens position P2, as will be described later. When the reliability of the defocus amount is low, the focus detection areas are rearranged as described above. When rearranged in this way, the defocus amount corresponding to the focus detection area after rearrangement is not output for a predetermined period. Here, it is assumed that the output is not performed for the three times “x” in FIG. Note that the number of times and the period are not limited to three because they vary depending on each system, the setting state (frame rate, shutter speed, etc.) and other conditions.

  At timing P2, the difference a between the latest contrast AF evaluation value and the past contrast AF evaluation value is calculated. In the example shown in FIG. 11A, since first threshold> difference a> 0, it is determined that the subject has not changed, and is based on the defocus amount (Def_bk) with high reliability before rearrangement. The focus lens 105 is controlled.

  Next, at timing P3, a difference b from the contrast AF evaluation value acquired at the previous time (timing P2) is calculated. In the example shown in FIG. 11A, the first threshold> difference b> 0, and the focus lens 105 is controlled again based on the defocus amount (Def_bk) with high reliability before the rearrangement. .

  Thereafter, at the lens positions P4 to P6, the focus lens 105 is based on the defocus amount with high reliability before the rearrangement by the same processing based on the difference c to the difference e from the previously acquired contrast AF evaluation value. To control.

  By performing the above processing, when the focus detection area is rearranged, the focus lens is referred to the contrast AF evaluation value until the defocus amount by the imaging surface phase difference method after the rearrangement is output. Can be controlled. Thus, when it can be determined that the subject has not changed, the focus lens can be controlled without deteriorating the quality of the moving image by continuing to drive the focus lens.

  FIG. 11B is a diagram illustrating a case where the amount of change in the contrast AF evaluation value decreases (the difference becomes negative) during “3: during the rearrangement period”. Since the lens position P2 is the same as that shown in FIG.

  In the example shown in FIG. 11B, at the timing P3, the contrast AF evaluation value is lower than the previously acquired contrast AF evaluation value, and the difference f from the previous contrast AF evaluation value is a negative value. Therefore, it is determined that the subject has changed. Therefore, since the defocus amount with high reliability before the rearrangement is the defocus amount before the subject is changed, it is inappropriate to use it. Therefore, by stopping the focus lens 105 until the defocus amount after the rearrangement is obtained, it is possible to prevent the deterioration of the quality of the moving image due to unnecessary driving of the focus lens 105.

  In the above description, it is determined that the subject has changed when the difference in contrast AF evaluation value is a negative value. However, the present invention is not limited to this. Considering the influence of noise on the contrast AF evaluation value, a predetermined threshold value B (negative value) is provided, and the subject is detected when the difference is equal to or smaller than the threshold value B. You may judge that it has changed.

  FIG. 11C is a diagram illustrating a case where the variation of the contrast AF evaluation value is equal to or greater than a threshold (abrupt increase) during “3: during the rearrangement period”. Since the lens position P2 is the same as that shown in FIG.

  In the example shown in FIG. 11C, at the timing P3, the contrast AF evaluation value is extremely higher than the previously acquired value, and the difference g from the previous contrast AF evaluation value exceeds the first threshold value. Since it is a value, it is determined that the subject has changed. Therefore, since the defocus amount with high reliability before the rearrangement is a focus detection result before the subject is changed, it is inappropriate to use it. Therefore, by stopping the focus lens 105 until the defocus amount after the rearrangement is obtained, it is possible to prevent the deterioration of the quality of the moving image due to unnecessary driving of the focus lens 105.

  In the above description, the first threshold value is a fixed value. However, the first threshold value may be changed under conditions such as the frame rate and the shutter speed that change the acquisition timing of the contrast AF evaluation value. You may change with camera states, such as a zoom state and a brightness state.

  In the first embodiment, the focus lens 105 is stopped when it is determined that the subject has changed. However, the drive speed of the focus lens 105 may be controlled to decrease.

  In the above description, the contrast AF evaluation value fluctuates at timing P3 which is temporally later than timing P2. However, the case where the contrast AF evaluation value fluctuates at timing P2 is also described above. It can be determined that the subject has changed by similar control.

  Considering that the timing at which the defocus amount by the imaging surface phase difference method is output is later than the timing at which the contrast AF evaluation value is output, the following possibilities are conceivable. In other words, when focus detection cannot be performed at timing P2, the contrast AF evaluation value may have fluctuated at a timing before timing P2. Therefore, instead of determining whether or not the subject has changed based on only the contrast AF evaluation value after timing P2, it is possible to determine whether to change the subject using the contrast AF evaluation value acquired at a timing before timing P2. .

  Next, an area (contrast AF area) for acquiring the contrast AF evaluation value will be described.

  The contrast AF area may be set to substantially the same area as the display AF frame 92 shown in FIG. 10, or the focus detection line that detects the defocus amount used for AF control, and the horizontal position. Accordingly, an area smaller than the display AF frame 92 may be set. In this way, by setting the contrast AF area in the vicinity where the defocus amount was detected before the rearrangement, when a subject different from the subject before the rearrangement enters and exits the display AF frame 92, the lens is erroneously driven. Can be reduced from stopping or continuing to drive.

  Further, when setting the contrast AF area, the contrast AF area is set so as to include the rearranged focus detection line adjacent to the focus detection line where the defocus amount is detected. For example, when the defocus amount is detected in the focus detection area 95b ′ before the rearrangement, the contrast AF area is set to include at least the focus detection areas 95e and 95f. By setting to include the focus detection areas 95e and 95f, the lens control is erroneously stopped by a slight time lag from when the subject enters the focus detection areas 95e and 95f until the defocus amount is detected (calculated). Or continuing driving can be reduced.

  According to the above determination method, when the amount of change is within the first threshold, it is determined that the subject in the contrast AF area has not changed and the subject has entered the gaps between the focus detection areas that are discretely arranged. To do. On the other hand, if “the amount of change exceeds the first threshold value”, it is determined that the subject in the contrast AF area has changed.

  Returning to the description of FIG. 8, if it is determined in S205 that the defocus amount is output in the focus detection area after the rearrangement, the detection area flag is set to “4: rearranged” in S207, and the process proceeds to S210. Migrate processing.

  In S210, the camera microcomputer 114 determines whether or not the reliability of the defocus amount received from the phase difference AF signal processing unit 113 is higher than the second threshold value. If it is determined that the value is higher than the second threshold value, the process proceeds to S211, the camera microcomputer 114 stores the received defocus amount in a predetermined RAM (defocus amount (Def_bk)), and the process proceeds to S220. Transition.

  On the other hand, in S210, when it is determined that the reliability of the defocus amount is equal to or less than the second threshold, the process proceeds to S212. In S212, the camera microcomputer 114 determines whether the detection area flag is “1: normal state”, “2: enlarged state”, or “4: rearranged state”. If it is determined that the state is “1: normal state”, the process proceeds to S213. If it is determined that it is “2: enlarged state”, the process proceeds to S214. If it is determined that “4: rearranged state”, the process proceeds to S215. , Each process is transferred.

  In S213, the focus detection area is changed to focus detection areas 95a ′ to 95d ′ shown in FIG. 10B, and the process proceeds to S216. After the detection area flag is changed to “2: enlarged state”, the process proceeds to S220. Migrate processing.

  In S214, the focus detection areas are rearranged in the focus detection areas 95e to 95g shown in FIG. 10C, the process proceeds to S217, the detection area flag is changed to “3: during rearrangement period”, and then S220. The process is transferred to.

  In S215, the camera microcomputer 114 determines whether or not the defocus direction reliability calculated in S106 is higher than the third threshold. If it is determined that the value is higher than the third threshold, the process proceeds to S218. If it is determined that the value is equal to or less than the third threshold, the process proceeds to S219.

  In S218, the camera microcomputer 114 sets direction information in the focusing drive unit 111 so as to drive the focus lens 105 in the defocus direction in which it is determined that the reliability is higher than the threshold value. In S219, the camera microcomputer 114 determines that the received defocus amount cannot be used, sets direction information in the focusing drive unit 111 so as to drive the focus lens 105 in a predetermined direction, and shifts the processing to S220. As an example of the predetermined direction, the direction is set so as to go to the far end or the infinite end of the focus lens 105 toward the end far from the current lens position.

  In S220, the focus lens 105 is driven according to each process described above.

  In the first embodiment, the focus detection area is returned to “1: normal state” when it is determined in S201 to S203 that there is a scene change. However, the present invention is not limited to this. is not. For example, when a highly reliable defocus amount is not obtained even in the case of rearrangement, the focus detection may be performed again after returning to the enlarged state (or the normal state). In addition, when a highly reliable defocus amount cannot be obtained in the normal state (or the enlarged state), the focus detection area is periodically switched between the enlarged state (or the normal state) and the rearrangement state, and each focus detection is performed. You may make it a structure which performs a focus detection based on a result.

  By adopting such a configuration, in the state where the focus detection area is rearranged, even if the subject enters the gap of the focus detection line again due to camera shake or vertical movement of the subject, focus detection can be performed correctly. It is possible to reduce a decrease in focus detection performance. However, when the period of camera shake and subject vertical movement is the same as the period of change of the focus detection area, the focus detection area and the position of the subject may be misplaced, and focus detection may not be performed correctly. For this reason, it is desirable not to simply switch between the enlarged state (or normal state) and the rearranged state, but to switch so as to be non-uniform in one cycle.

  Further, in the first embodiment, the case where the focus detection lines are discretely set with respect to the AF frame has been described. However, the present invention is not limited to this, and a grouped area may be set. The interval may be variable.

  As described above, according to the first embodiment, in the focus adjustment apparatus capable of focus detection only in a limited area with respect to the imaging area, the subject comes out of the preset focus detection area. Therefore, it is possible to reduce the deterioration of the focus detection performance. Also, when an area different from the preset focus detection area is set, even if there is a time lag in the output of focus detection results in the newly set area, it is appropriate to determine whether to keep moving the lens or not Can be done.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. In the first embodiment described above, when a reliable defocus amount cannot be obtained by focus detection in the imaging surface phase difference method, focus detection is performed by expanding the focus detection area and changing the arrangement of the focus detection lines. The process to continue has been described.

  In contrast, the second embodiment is characterized in that the contrast AF is continued as a process when the defocus amount cannot be obtained even if the focus detection area is expanded and the focus detection line is rearranged. Yes. Hereinafter, switching to contrast AF will be described.

  Here, first, contrast AF performed in the second embodiment will be described with reference to the flowchart of FIG. 12 is executed by the image sensor 106, the contrast AF signal processing unit 116, and the camera microcomputer 114 that controls them.

  First, in S401, the camera microcomputer 114 determines the presence / absence of drive direction information set in a focus detection area setting process described later in the second embodiment.

  If there is no driving direction information, the process proceeds to S402, and a contrast AF evaluation value calculated based on an image signal in the contrast AF area output through the contrast AF gate 115 and the contrast AF signal processing unit 116 is acquired. .

  Next, in S403, a minute driving operation for repeatedly driving the focus lens 105 within a predetermined narrow range is performed. The contrast AF evaluation value is detected while performing the minute driving operation, and the direction in which the contrast AF evaluation value increases is set as the in-focus direction. When the same in-focus direction continues for a predetermined period, the in-focus direction is determined. If the in-focus direction reciprocates a predetermined number of times in the same area, the in-focus determination is made assuming that the peak of the contrast AF evaluation value is detected. The minute driving operation in S403 is repeatedly performed until the in-focus direction is determined in S404.

  When the in-focus direction is determined in S404, the in-focus determination in the minute driving operation is subsequently performed in S405. If the focus is not determined in S405, the process proceeds to S406 and a hill-climbing driving operation is performed.

  In hill-climbing driving, the focus lens 105 is driven at high speed in a direction in which the contrast AF evaluation value increases based on the in-focus direction determined in S404 or the driving direction information in the focus detection area setting process determined in S401. . The hill-climbing driving operation is repeated until it is determined in S407 that the peak of the contrast AF evaluation value has been exceeded. In step S408, the focus lens 105 is returned to the lens position at which the contrast AF evaluation value during hill-climbing driving reaches a peak. If it is determined in S409 that the peak has been returned, the process returns to S402, and the minute driving operation is performed again. If it is determined in S409 that the lens position has not been returned to the peak lens position, the process returns to S408 to continue the operation of returning to the peak lens position.

  Next, the focusing operation from S410 will be described. In S410, the contrast AF evaluation value is held. In step S411, the latest contrast AF evaluation value is acquired. In S412, the contrast AF evaluation value held in S410 is compared with the contrast AF evaluation value newly acquired in S411. If the difference between the contrast AF evaluation values is greater than or equal to a predetermined value, it is determined that the operation has been restarted, and the process proceeds to S402 to restart the minute driving operation. If the difference is smaller than the predetermined value in S412 and it is not determined to restart, the process proceeds to S413. In S413, the focus lens 105 is stopped, the process returns to S411, and the restart determination is continued.

  Next, focus detection area setting processing in the second embodiment will be described with reference to the flowchart of FIG. In FIG. 13, the process indicated by the same reference numeral as in FIG. 8 indicates the same process as in FIG. 8, and the description thereof is omitted here.

  In the second embodiment, if the defocus amount cannot be obtained even if the focus detection area is enlarged and the focus detection line is changed, the process branches to S502, and the process of switching to contrast AF is performed. Be started.

  First, in S502, it is determined whether the focus lens 105 is being driven. If it is driven, the process proceeds to S503. If it is not driven (stopped), the process proceeds to S507.

  In step S503, the amount of change in the contrast AF evaluation value is monitored from the contrast AF evaluation value detected by the contrast AF signal processing unit 116. If the amount of change is within the fourth threshold, the subject is correctly captured. The process proceeds to S504. In S504, the reliability of the defocus amount (Def_bk) backed up by the contrast AF signal processing unit 116 is determined. If it is determined that the reliability is higher than the fifth threshold value, the process proceeds to S505 and the previous phase difference method is used. A driving direction is set based on the determined driving direction. As described above, in contrast AF, by setting this driving direction as the initial value of the in-focus direction, it is possible to skip the in-focus direction determination process and proceed to search for the in-focus position. When the drive direction is set, the process proceeds to S513, where a contrast AF processing routine is activated to start contrast AF control.

  On the other hand, in the determination of S503, when it is determined that the variation amount of the contrast AF evaluation value exceeds the fourth threshold and the subject has not been captured, and the reliability of the defocus amount (Def_bk) backed up in S504 is low. If it is determined, the process proceeds to S506. In S506, the information on the driving direction is cleared, and in contrast AF, the process is started from the determination of the focusing direction by minute driving.

  Next, the case where it is determined in S502 that the focus lens is stopped will be described. First, in step S507, the defocus amount backup is confirmed. If there is no backup, since the defocus amount is not detected at all by the phase difference method, the process proceeds to S509 and the drive direction is cleared. By clearing the drive direction, the process starts from determination of the focus direction by minute drive of contrast AF control.

  If there is a backup and if it is determined in S508 that the contrast AF evaluation value has changed, it is determined that the subject has moved from the focused state, and the process proceeds to S509 to clear the drive direction. By clearing the driving direction, the processing is started from determination of the in-focus direction by minute driving of contrast AF control. If it is determined in S508 that there is no change in the contrast AF evaluation value, it is determined that the in-focus state is maintained, the driving of the focus lens 105 is stopped in S510, and the driving direction is cleared in S511. In step S512, the contrast AF is stopped.

  Note that the focus detection processing by the phase difference method is continuously performed even during contrast AF. If it is determined in S210 that the reliability of the defocus amount measured by the phase difference method is equal to or greater than the threshold value, the process proceeds to S220 via S211 and the focus control of the focus lens 105 is performed based on the defocus amount measured by the phase difference method. To implement. Further, during the focus adjustment process by the phase difference method, the contrast AF is stopped in S501.

  Further, the “change in contrast AF evaluation value” in S508 may be a change from the contrast AF evaluation value output at the previous contrast AF evaluation value output timing or a change from the contrast AF evaluation value a predetermined number of times ago. .

  As described above, according to the second embodiment, the following effects can be obtained in addition to the same effects as those of the first embodiment. In other words, if focus detection cannot be performed using the phase difference method even if the focus detection area is enlarged or the focus detection line is changed, switching to contrast AF and continuing AF control will reduce the focus detection performance. Can be reduced.

(Other embodiments)
Further, the present invention supplies a program that realizes one or more functions of the above-described embodiment 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 execute the program. It can also be realized by a process of reading and executing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  In addition, the present invention is not limited to a device mainly intended for shooting such as a video camera, and has a built-in focusing device such as a mobile phone, personal computer (laptop type, desktop type, tablet type, etc.), game machine, or It can be applied to any device connected externally. Accordingly, the “focus adjustment device” in this specification is intended to include any electronic device having a focus adjustment function. As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to the said embodiment, A various deformation | transformation and change are possible within the range of the summary.

  105: Focus compensator lens, 106: Image sensor, 111: Focusing drive unit, 112: Phase difference AF gate, 113: Phase difference AF signal processing unit, 114: Camera microcomputer, 115: Contrast AF gate, 116: Contrast AF Signal processing unit, 117: phase difference AF pixel readout setting unit, 200: pixel, 305: microlens

Claims (23)

A first readout control that has a plurality of photoelectric conversion units for each of the plurality of microlenses arranged in a matrix, and reads out signals from the plurality of photoelectric conversion units so as to obtain a pair of focus detection signals; A second readout control that reads out the addition signal by adding the charges accumulated in the plurality of photoelectric conversion units corresponding to each microlens, and an image sensor that can be read out by switching,
Setting means for setting a row to be read by the first readout control among a plurality of rows to be read by the second readout control including a predetermined first focus detection region;
First focus detection means for detecting a focus state by a phase difference method using a pair of focus detection signals obtained from a part of the rows read out by the first readout control; Have
The image pickup apparatus, wherein the setting unit changes a setting of a row to be read by the first read control based on a predetermined condition.   The setting unit reads a row read by the first read control when the reliability of the focus state detected by the first focus detection unit is lower than a predetermined first threshold. The imaging apparatus according to claim 1, wherein the setting is changed to a row that has not been read out by readout control. The first focus detection means expands a range for obtaining a pair of focus detection signals used for detection of the focus state when the reliability of the detected focus state is lower than a predetermined second threshold,
The setting means performs the first reading when the reliability of the focus state detected by the first focus detection means is lower than the first threshold after expanding the range for obtaining the pair of focus detection signals. The imaging apparatus according to claim 2, wherein a row to be read is changed by control.   The imaging apparatus according to claim 1, wherein the setting unit periodically changes a row read by the first read control.   The setting means sets a row to be read by the first read control within a range in which a signal can be read from a predetermined region of the image sensor in a predetermined period. 5. The imaging device according to any one of 4.   The setting means sets a row to be read by the first read control every predetermined number of rows among the plurality of rows of the plurality of photoelectric conversion units including the first focus detection region. The imaging apparatus according to claim 3. Determining means for determining a driving amount and a driving direction of the focus lens based on the focus state detected by the first focus detecting means;
Further comprising second focus detection means for detecting a focus state by a contrast method based on the addition signals obtained from the plurality of photoelectric conversion units included in the predetermined second focus detection region;
The determination means detects the second focus detection means until the detection of the focus state is completed by the first focus detection means after the row read by the first read control is changed by the setting means. 2. The method according to claim 1, further comprising: determining whether to drive the focus lens according to the focus state obtained by the first focus detection unit before the change based on the focus state. The imaging device according to any one of 6.   The determination unit is configured to change the focus state detected by the second focus detection unit within a predetermined threshold when changing the row read by the first read control by the setting unit. The imaging apparatus according to claim 7, wherein the focus lens is determined to be driven according to a focus state obtained by the first focus detection unit before the change.   The determining unit is configured to change the focus state detected by the second focus detecting unit when the row to be read by the first reading control is changed by the setting unit when the amount of variation in the focus state exceeds the predetermined threshold. The imaging apparatus according to claim 8, wherein it is determined to stop driving the focus lens.   The said 2nd focus detection area | region contains the area | region which detected the said focus state by the said 1st focus detection means before the said change, The any one of Claim 7 thru | or 9 characterized by the above-mentioned. Imaging device.   The determination means is obtained by the second focus detection means when the reliability of the focus state detected by the first focus detection means after the change is equal to or less than a predetermined third threshold value. The imaging apparatus according to claim 7, wherein a driving amount and a driving direction of the focus lens are determined based on a focus state.   While the focus lens is being driven, the amount of change in the focus state detected by the second focus detection means is within a predetermined fourth threshold value, and the first focus detection before the change When there is a focus state in which the reliability obtained by the means is higher than a predetermined fifth threshold, the determination means uses the focus obtained by the first focus detection means as the initial value of the driving direction. The imaging apparatus according to claim 11, wherein a direction of the focus lens is determined based on a state.   When the fluctuation amount of the focus state detected by the second focus detection unit exceeds a predetermined sixth threshold, the determination unit determines the focus lens in advance in order to determine the drive direction. The imaging apparatus according to claim 11, wherein it is determined that the driving is repeated within a specified range.   When the focus lens is stopped and there is no focus state in which the reliability obtained by the first focus detection means before the change is higher than a predetermined seventh threshold, the determination means The imaging apparatus according to claim 11, wherein, in order to determine the driving direction, it is determined that the focus lens is repeatedly driven within a predetermined range.   The determination unit is configured to detect the focus obtained by the first focus detection unit when the reliability of the focus state detected by the first focus detection unit is higher than the first threshold after the change. The imaging apparatus according to claim 11, wherein a driving amount and a driving direction of the focus lens are determined based on a state. A driving method of an image sensor having a plurality of photoelectric conversion units for each of a plurality of microlenses arranged in a matrix,
The setting unit reads signals so as to obtain a pair of focus detection signals from the plurality of photoelectric conversion units among the plurality of rows of the plurality of photoelectric conversion units including the predetermined first focus detection region. A row to be read by the first read control and a row to be read by the second read control for adding the charges accumulated in the plurality of photoelectric conversion units corresponding to the respective microlenses and reading the addition signal are set in units of rows. A setting process to
A reading step in which a reading unit switches and reads the first reading control and the second reading control set by the setting unit from the plurality of photoelectric conversion units;
A first focus detection unit detects a focus state by a phase difference method using a pair of focus detection signals obtained from a part of a range of rows read by the first read control. 1 focus detection step, and
In the setting step, the setting of a row to be read by the first read control is changed based on a predetermined condition, and the image sensor driving method is characterized in that:   In the setting step, when the reliability of the focus state detected in the first focus detection step is lower than a predetermined first threshold, a row read by the first read control is set as the first read control. The image sensor driving method according to claim 16, wherein the setting is changed to a row that has not been read out by readout control. The first focus detection unit expands a range for obtaining a pair of focus detection signals used for detection of the focus state when the reliability of the detected focus state is lower than a predetermined second threshold. Process,
When the setting means expands the range for obtaining the pair of focus detection signals and the reliability of the focus state detected in the first focus detection step is lower than the first threshold value, the first reading is performed. The method for driving an image sensor according to claim 17, wherein a row to be read is changed by control.   The image sensor driving method according to claim 16, wherein, in the setting step, a row to be read by the first read control is periodically changed. A determining step for determining a driving amount and a driving direction of the focus lens based on the focus state detected in the first focus detection step;
A second focus for detecting a focus state by a contrast method based on an addition signal obtained from the plurality of photoelectric conversion units included in the predetermined second focus detection region; Further comprising a detection step,
In the determination step, after the row read by the first read control is changed in the setting step, detection is performed in the second focus detection step until detection of the focus state is completed in the first focus detection step. 17. The method according to claim 16, further comprising: determining whether to drive the focus lens according to the focus state obtained in the first focus detection step before the change based on the focused state. The image sensor driving method according to any one of 19.   Obtained in the second focus detection step in the determination step when the reliability of the focus state detected in the first focus detection step after the change is equal to or less than a predetermined third threshold value. 21. The image sensor driving method according to claim 20, wherein a driving amount and a driving direction of the focus lens are determined based on a focus state.   The program for making a computer perform each process of the drive method of the image pick-up element of any one of Claims 16 thru | or 21.   A computer-readable storage medium storing the program according to claim 22.

Images