JP5217942B2 - Focus adjustment device and imaging device - Google Patents

Description

  The present invention relates to a focus detection apparatus and an imaging apparatus.

In the control of the focus detection image sensor for detecting the focus adjustment state of the photographing optical system, when it is necessary to perform focus detection simultaneously in a plurality of focus detection areas with greatly different brightness, the brightness for each focus detection area There has been known a focus detection apparatus in which charge accumulation is performed a plurality of times for each focus detection with an accumulation time suitable for this (see, for example, Patent Document 1).
Patent No. 3203742

  However, when the focus detection area increases, there is a problem that the focus detection calculation time increases, and the change in the subject situation during focus detection becomes large.

According to a first aspect of the present invention, there is provided a focus adjustment apparatus including: a microlens array in which a plurality of microlenses are arranged in a two-dimensional manner; and a light reception in which a plurality of charge storage photoelectric conversion elements are arranged in a two-dimensional manner with respect to the microlens array. A light receiving means for outputting a signal obtained by receiving the light transmitted through the optical system by the light receiving element array through the microlens array, and set in an image plane by the optical system. Control means for sequentially controlling charge accumulation at a plurality of different charge accumulation times for the photoelectric conversion element arrays corresponding to each of a plurality of focus detection regions, and the plurality The focus detection of the optical system is performed based on the output signal of the photoelectric conversion element array corresponding to each of the focus detection areas, and a plurality of focus detection results and the focus detection results are matched. A plurality of reliability determination results and focus detection means for calculating a that, selection of the basis plurality of focus detection result and the said plurality of reliability determination results, selecting a predetermined focus detection area from the plurality of focus detection areas And a focus adjusting means for adjusting the focus of the optical system based on a focus detection result in the selected focus detection area, and after the focus adjustment of the optical system by the focus adjusting means, the control means Is the charge accumulation time in which the reliability determination result corresponding to the selected focus detection region has the highest value among the plurality of charge accumulation times, and the photoelectric response corresponding to the selected focus detection region. The charge accumulation control is performed again on the conversion element array, and the focus detection unit refocuses the optical system based on the output signal of the photoelectric conversion element array on which the charge accumulation control is performed again. It performs output, calculates a focus detection result, the focusing means, and performs focus adjustment of the focus detection based on the results again of the optical system.

  According to the present invention, even if there are a large number of focus detection areas for performing focus detection, focus detection can be performed in a short time in those focus detection areas.

  1A and 1B are cross-sectional views of a camera (imaging device) including a focus detection device according to an embodiment. FIG. 1A shows a state during non-shooting, and FIG. 1B shows a state during shooting exposure. In FIG. 1, illustration and description of camera devices, circuits, and apparatuses that are not directly related to the focus detection apparatus and the imaging apparatus of the present invention are omitted. In a camera according to an embodiment, a lens barrel 2 is attached to a camera body 1. The lens barrel 2 can be replaced with a lens barrel having various photographing lenses.

  The camera body 1 includes a main mirror 11, a sub mirror 12, a shutter 13, an image sensor 14, a focus detection device 15, a control device 16, a pentaprism 17, an eyepiece lens 28, a contact point 19, and the like. The image sensor 14 is composed of a CCD, a CMOS, or the like, and converts the subject image formed by the photographing lens into an electrical signal and outputs it. On the subject side of the shutter 13, an optical member 27 that is a combination of an optical low-pass filter and an infrared cut filter is installed. The focus detection device 15 detects the focus adjustment state of the photographing lens. Details of the focus adjusting device 15 will be described later. The control device 16 includes a microcomputer (not shown), ROM, RAM, A / D converter, and the like, and performs various calculations and sequence control of the camera.

  The lens barrel 2 includes a photographing lens 21 (21a to 21e), a diaphragm 22, a lens drive control device 23, and the like. The lens drive control device 23 includes a microcomputer (not shown), a memory, a lens drive motor, a diaphragm drive motor, and the like, and performs focus adjustment of the photographing lens 21, aperture adjustment of the diaphragm 22, and the like. The control device 16 of the camera body 1 and the lens drive control device 23 of the lens barrel 2 exchange various information via a contact point 19 provided in an interchangeable lens mount unit (not shown).

  At the time of non-photographing, as shown in FIG. 1A, the main mirror 11 and the sub mirror 12 are placed in the photographing optical path, and part of the subject light transmitted through the photographing lens 21 is the main mirror 11, the pentaprism 17, and the eyepiece 28. The subject image is visually recognized by the photographer. Further, the remaining part of the subject light is guided to the focus detection device 15 via the main mirror 11 and the sub mirror 12, and the focus detection state of the photographing lens 21, that is, the defocus amount is detected by the focus detection device 15.

  At the time of photographing exposure, as shown in FIG. 1B, the main mirror 11 and the sub mirror 12 are retracted from the photographing optical path, and the subject light transmitted through the photographing lens 21 is guided to the photographing element 14, and the imaging element 14 captures the subject image. Imaging is performed. The subject image signal output from the image sensor 14 is processed by a signal processing circuit (not shown) and then recorded on a recording medium such as a memory card.

  FIG. 2 shows a configuration of a focus detection optical system incorporated in the focus detection apparatus of one embodiment. The taking lens 21 forms a subject image on the light receiving surface 14a of the image sensor 14 (see FIG. 1). The light beam (focus detection light beam) from the subject that has passed through the photographic lens 21 is reflected by the reflecting surface 12a of the sub mirror 12 (see FIG. 1), and is guided to the planned focal plane 15a conjugate with the imaging element light receiving surface 14a. A subject image is formed on the surface 15a. Note that the focus of the photographic lens 21 is adjusted so that the subject image is focused on the planned focal plane 15a.

  When focus detection is performed using a focus detection light beam at a high image height, a field lens 51 is inserted in the optical path, specifically from the vicinity of the planned focal plane 15a, between the microlens array 52 described later. The light beam at the high image height may be bent from the optical axis direction. In the following description, the field lens 51 is ignored.

  In the focus detection device 15, a microlens array 52 and a light receiving element array 53 are enclosed in a package 55 that is covered with a cover glass 54. FIG. 3 is an enlarged perspective view of the microlens array 52 and the light receiving element array 53. In practice, the microlens array 52 and the light receiving element array 53 are in close contact with each other, but in FIG. 3, they are shown separately for easy understanding. The microlens array 52 is disposed in the vicinity of the planned focal plane 15a of the camera.

  Although not shown in FIG. 3, a light-shielding partition for preventing crosstalk between the microlenses is provided between the microlenses and the side surface of the lens substrate. The light shielding partition is formed by forming a grid-like deep groove in the microlens by machining or etching, and filling the groove with a light shielding resin.

  The light receiving element array 53 is disposed very close to the microlens array 52, and a plurality of photoelectric conversion elements (hereinafter referred to as light receiving elements) are arranged two-dimensionally for each microlens. In this embodiment, an example is shown in which a light receiving element array 53 in which 5 × 5 light receiving elements are arranged for each microlens is used. The number of light receiving elements for each microlens is described in this embodiment. The light receiving elements are not arranged for each microlens, and a plurality of light receiving elements may be simply arranged two-dimensionally.

  4 and 5 are diagrams for explaining the focus detection method according to the embodiment, and show XZ cross sections of the microlens array 52 and the light receiving element array 53 shown in FIG. One microlens and a light receiving element array corresponding to the microlens are referred to as pixels in this specification for convenience. In the example shown in FIGS. 4 and 5, the microlens and the five light receiving elements arranged corresponding to the microlens are one pixel. In the focus detection device of this embodiment, an image formed by each microlens of the light receiving element array of each pixel is formed on the subject side with respect to the apex of each microlens, and this imaging surface is planned. A microlens array (focus detection optical system) 52 and a light receiving element array 53 are arranged so as to coincide with the focal plane 15a.

  The focus detection apparatus according to this embodiment obtains a defocus amount based on a positional deviation of a pair of images by subject light that has passed through different areas of the pupil plane of the photographing lens 21 in the vicinity of the detection plane. This is a phase difference detection type focus detection device.

  First, in the first focus detection calculation method, a defocus amount is calculated based on a shift amount between images detected by light receiving element arrays of adjacent pixels or pixels at a predetermined interval. For example, in FIG. 4, the shift amount of the image on the two light receiving element rows of the two adjacent pixels, that is, “light receiving element rows A and B” represented by A ′ and B ′ on the planned focal plane 15a. The defocus amount is calculated based on the shift amount of the subject image formed by the photographic lens 21 at the position of the “backprojected image”.

  In the second focus detection calculation method, in a plurality of adjacently arranged pixels, an image generated by continuously connecting the nth light receiving element outputs from the end of the light receiving element row of each pixel, and the (n + m) th light receiving element A defocus amount is calculated based on a deviation amount from an image generated by combining outputs. For example, in FIG. 4, the image of the light receiving element row C from the left in the light receiving element row of each pixel is connected to the light receiving element row C and the output of the fourth light receiving element d from the left is connected to the light receiving element row. The amount of deviation from the image defined as D, that is, the deviation of the subject image formed by the photographing lens 23 at the position of the “back-projected image of the light receiving element rows C and D” represented by C ′ and D ′ on the planned focal plane 16. The defocus amount is calculated from the amount.

  As a modification of the second focus detection calculation method, as shown in FIG. 5, an image in which the addition values of the first and second light receiving element outputs from the left are combined to form a light receiving element array C, and 4 from the left. The amount of deviation from the image formed as the light receiving element array D by combining the added values of the outputs of the fifth and fifth light receiving elements, that is, “back projection of the light receiving element arrays C and D represented by C ′ and D ′ on the planned focal plane 16 The defocus amount may be calculated based on the shift amount of the subject image formed by the photographing lens 23 at the position of “image”.

  FIG. 6 is a block diagram illustrating a detailed configuration of the focus detection device 15 (see FIG. 1) according to an embodiment. The output of the two-dimensional light receiving element array 53 (see FIG. 3) is converted into a digital signal by the A / D converter 54 and temporarily stored in the memory 55. The microcomputer 56 includes a composite signal sequence creation unit 56a, an image shift calculation unit 56b, and a focus amount calculation unit 56c in software form, reads out the output data of the light receiving element array 53 from the memory 55, and the composite signal sequence creation unit 56a 1 signal sequence {a (i)} = a (1), a (2), a (3),..., And second signal sequence {b (i)} = b (1), b (2) , B (3),.

  Here, in the case of the first focus detection method described above, the signal sequences {a (i)} and {b (i)} are the light receiving element outputs of the light receiving element arrays of the adjacent pixels A and B shown in FIG. It is a line of. In the case of the second focus detection method described above, the signal sequences {a (i)} and {b (i)} are an arrangement of the outputs of the light receiving element arrays C and D shown in FIG.

Based on the first signal sequence {a (i)} and the second signal sequence {b (i)} obtained in this way, an image shift calculation is performed by a known method to calculate a defocus amount. A method of calculating a defocus amount from two signal sequences {a (i)} and {b (i)} is well known. First, a first signal sequence {a (i)} and a second signal sequence {b (i)} The correlation amount C (N) of the corresponding pair of images is obtained from (i = 1, 2, 3,...).
C (N) = Σ | a (i) −b (j) | (1)
In the equation (1), the shift number N is N = j−i, and Σ represents the total operation of i = pL to qL.

The shift amount is obtained from the correlation amount C (N) obtained discretely by the equation (1) as follows. Here, among the correlation amounts C (N), the correlation amount giving a minimum value when the shift amount N = N0 is C0, the correlation amount in the shift amount (N0-1) is Cr, and the correlation amount in the shift amount (N0 + 1). Let the amount be Cf. A precise shift amount Na is obtained from the arrangement of the correlation amounts Cr, C0, and Cf.
DL = 0.5 · (Cr−Cf) (2),
E = MAX {Cf-C0, Cr-C0) (3),
Na = N0 + DL / E (4)
Next, a correction amount (constant CONST) corresponding to the position of the focus detection surface is added to the shift amount Na to calculate an image shift amount Δn = Na + CONST on the focus detection surface. Further, the defocus amount Df is calculated by multiplying the image shift amount Δn by a constant Kf depending on the detected opening angle.
Df = Kf · Δn (5)

  With the above-described focus detection procedure, it is possible to perform focus detection on a subject image in the focus detection region using a signal sequence output from a pixel row corresponding to a desired focus detection region in the shooting screen.

  In this embodiment, in the focus detection procedure described above, the charge accumulation operation in each focus detection region is performed as follows. That is, the charge accumulation operation of all the focus detection areas on the light receiving element array 53 is sequentially performed with three kinds of accumulation times of preset long, medium, and short, and the focus detection calculation is performed in the necessary focus detection area each time. To store the calculation result in the memory. Hereinafter, this operation is referred to as “sequential accumulation” operation.

  In the focus detection calculation of one embodiment, the reliability of the focus detection result is determined by a conventionally known method. If the accumulation time is too short or too long with respect to the intensity of the subject light, the signal sequence is not well correlated in the calculation process, so that it is determined that there is no reliability. The reliability determination result is stored in the memory as a part of the focus detection result.

  By adopting the focus detection results determined to be sufficiently reliable among the focus detection results obtained in the above-described three types of charge accumulation times of long, medium, and short in each necessary focus detection region. In addition, a reliable focus detection result can be obtained in each of a large number of focus detection areas even on a screen in which subjects with large brightness differences are mixed.

  In the camera of this embodiment, the photographer can select the “focus detection area automatic selection mode” or the “focus detection area manual selection mode” by operating the operation member. When the focus detection area automatic selection mode is set, the control device 16 performs a sequential accumulation operation using the three types of charge accumulation times described above. The focus detection area automatic selection mode is a mode in which the camera automatically estimates a target to be focused from the whole or a wide area of the photographing screen, that is, a main subject and focuses. When estimating the main subject, the focus detection result of each focus detection area is used. Various algorithms are known, for example, the closest subject is regarded as the main subject. Of course, detection results other than focus detection, such as photometric sensor data and feature point extraction results from captured images, can also be considered.

  In the light receiving element array 53 shown in FIG. 3, only a small number of pixels are shown for convenience of explanation, but actually a large number of pixels are arranged. Therefore, the focus detection device of one embodiment is orders of magnitude larger than the conventional one. Many focus detection areas can be set. Of these, a focus detection calculation is performed in a focus detection region where a main subject is estimated to exist.

  The three types of charge accumulation times set in advance are stored in the nonvolatile memory at the time of manufacture and shipment. Of course, the types of charge accumulation time are not limited to the three types in this embodiment, and there may be two types or four or more types. For example, when a split photometry sensor is installed and the release button is pressed halfway, the output of the photometry sensor is input, and the output distribution of the photometry sensor for each of the divided photometry areas is brighter than the first predetermined value , Exclude “long” from the three types of long, medium and short accumulation times, and set the accumulation time between “medium” and “short”, or between “medium” and “short” The accumulation operation is executed with the newly added three types of charge accumulation times. Further, when the output distribution of the photometric sensor for each of the divided photometric areas is darker than the second predetermined value, “short” is excluded from the three types of accumulation times of long, medium and short, and “long” And “medium”, or three kinds of charge accumulation times obtained by newly adding an intermediate accumulation time between “long” and “medium”.

  A plurality of sets of charge accumulation times are set and recorded in the memory at the time of manufacture, and the light receiving element array 53 of the focus detection device, photometry from when the camera is turned on until the focus detection operation is started. Any accumulation time set may be selected according to a predetermined algorithm based on the output of the sensor, the image sensor 14 or the like.

  On the other hand, when the focus detection region manual selection mode is set, the control device 16 has a good luminance distribution in that portion in accordance with the pixel column output on the image sensor corresponding to the manually selected focus detection region. The accumulation time is controlled so that it can be detected.

  7 and 8 are flowcharts illustrating the focus detection operation according to the embodiment. The operation of the embodiment will be described with reference to these flowcharts. When a shutter button (not shown) is half-pressed, the control device 16 starts the focus detection operation shown in FIGS. In step 1, the setting state of the focus detection area selection mode is checked. In step 2, it is determined whether or not the focus detection area automatic selection mode is set. If the automatic selection mode is set, the process proceeds to step 3. If the manual selection mode is set, the process proceeds to step 21.

  When the focus detection area automatic selection mode is set, in step 3, one of the charge accumulation time sets stored in advance in a memory (not shown) as described above is selected according to the output of the photometric sensor. Select and set a set. In this embodiment, it is assumed that a plurality of sets of long, medium and short charge accumulation times are stored. In step 4, charges are accumulated in the light receiving element array 53 in the first accumulation time in the accumulation time set, and in the subsequent step 5, the above-described operation is performed based on pixel column outputs corresponding to all focus detection areas on the light receiving element array 53. The focus detection calculation and reliability determination are performed, and the focus detection result and the reliability determination result are stored in the buffer memory.

  Next, in step 6, charges are accumulated in the light receiving element array 53 during the second accumulation time in the accumulation time set, and in step 7, pixel row outputs corresponding to all focus detection areas on the light receiving element array 53 are output. Based on the above-described focus detection calculation and reliability determination, the focus detection result and the reliability determination result are stored in the buffer memory. Further, in step 8, charges are accumulated in the light receiving element array 53 during the third accumulation time in the accumulation time set, and in the subsequent step 9, based on pixel column outputs corresponding to all focus detection areas on the light receiving element array 53. The focus detection calculation and reliability determination described above are performed, and the focus detection result and the reliability determination result are stored in the buffer memory.

  In step 10 of FIG. 8, the focus detection results of all the focus detection areas are read from the buffer memory, and the focus detection area in which the main subject is estimated to be present is selected based on these results as described above. In step 11, it is determined whether or not the taking lens 21 is in focus in the selected area, and if it is in focus, the focus detection operation is terminated. If the photographic lens 21 is not in focus in the selected focus detection area, the process proceeds to step 12, and the photographic lens 21 is driven based on the focus detection result in the selected area to adjust the focus.

  In step 13, it is determined whether or not the lens driving amount is equal to or less than a predetermined value. If the lens driving amount is larger than the predetermined value, it is considered that the focus adjustment state is “large blur” before driving the lens, and the process returns to step 4 and starts again from the automatic selection processing of the focus detection area. On the other hand, if the lens drive amount is less than or equal to the predetermined value, the process proceeds to step 14 and the accumulation operation is repeated in the charge accumulation time that has yielded the most reliable detection result in the selected focus detection area. In step 15, focus detection calculation is performed based on the pixel row output corresponding to the selected focus detection area, and in subsequent step 16, it is determined whether or not the selected area is in focus. If focus is achieved, the focus detection operation is terminated. If focus is not achieved, the process returns to step 12 to repeat the above-described processing.

  On the other hand, when the focus detection region manual selection mode is set, in step 21, an initial value is set for the charge accumulation time. In subsequent step 22, charge accumulation control is performed according to the determined accumulation time. In step 23, focus detection is performed in the manual selection area, and in step 24, it is determined whether or not the focus is achieved. If focus is achieved, the focus detection operation is terminated. If it is not in focus, the process proceeds to step 25, and the photographic lens 21 is driven based on the focus detection result in the manual selection area. In step 26, the charge accumulation time is determined according to the magnitude of the subject image signal output in the manual selection area, and the process returns to step 22 to repeat the above-described processing.

<< Other Embodiments of the Invention >>
FIG. 9 is a cross-sectional view illustrating a configuration of a moving-image camera (imaging device) including a focus detection device according to another embodiment. In the camera of this embodiment, a lens barrel 212 is attached to the camera body 211. The lens barrel 212 can be replaced with a lens barrel having various photographing lenses 213.

  The light from the subject that has passed through the photographing lens 213 is branched by the semi-transmissive pellicle mirror 214. The reflected light from the semi-transmissive pellicle mirror 214 is guided to the image sensor 217 via the optical low-pass filter and the infrared cut filter 216, and a subject image is formed on the light receiving surface. The camera is not provided with a viewfinder, and an image captured by the image sensor 217 is displayed on the LCD monitor 218 on the back of the camera. On the other hand, the light from the subject that has passed through the semi-transmissive pellicle mirror 214 is guided to the focus detection device 215, and the focus detection of the photographing lens 213 is performed by the focus detection device 215.

  When a shutter button release operation is performed, focus detection is performed by the focus detection device 215 while a still image or a moving image is captured by the image sensor 217. The focus detection device 215 has the same configuration as that of the focus detection device 15 according to the above-described embodiment. However, the screen is widened by increasing the number of lenses of the microlens array 52 and covers almost the entire area of the shooting screen. This focus detection device 215 has a plurality of charge accumulation times, as in the above-described embodiment, and performs charge detection calculation and reliability determination each time charge accumulation is performed at each accumulation time ( Sequential accumulation operation). Based on the focus detection result and the reliability determination result, the focus detection area where the main subject exists is estimated.

  The plurality of charge accumulation times are set at the time of manufacture and stored in a nonvolatile memory. A predetermined program is set based on the outputs of the light receiving element array, the photometric sensor, the image sensor 217, etc. of the focus detection device 215 during the period from when the camera is turned on until the camera is released. Any one of the charge accumulation time sets may be selected.

<< Modification of Embodiment of Invention >>
In the camera according to the embodiment described above, when one of a plurality of sets of a plurality of types of charge accumulation times stored in advance is selected, the first predetermined frame shooting is performed during still image shooting and moving image shooting. One of the accumulation time sets may be selected based on the output of the imaging element or the light receiving element array of the focus detection apparatus acquired during this period, and applied to subsequent frames.

  In the camera according to the embodiment described above, the focus detection results of a number of focus detection areas are used to focus the photographic lens on the main subject when the focus detection area automatic selection mode is set. It may be used. For example, in a single-lens reflex camera, the selection area may be displayed in the viewfinder by a known superimpose technique. Further, as a result of focus adjustment, the display color or display form of the focused focus detection area may be displayed differently from other areas. For example, when a focus detection area is selected, a frame line representing the area is displayed for a moment, and when it is in focus, the frame line is displayed for a longer time.

  In the case of still image continuous shooting and movie shooting, attached information is added to continuous shooting and movie recording in order to extract and use parts or frames that meet certain conditions such as “in focus” after shooting. It is known to record. As an application, it is recorded as additional information which focus detection area is selected for each frame or every predetermined time, and which focus detection area is in focus, and later extraction. It may be used for processing.

  In the above-described embodiment and its modification, the example in which the light receiving element array is sequentially accumulated in a plurality of charge accumulation times when the focus detection region automatic selection mode is set has been described. On the other hand, it is possible to switch between performing the above-described sequential accumulation operation according to the difference in mode setting related to the display of the focus detection area or performing the operation for adjusting the accumulation time according to the subject luminance. In the single-lens reflex camera, when the focus detection area is displayed in the viewfinder using the superimpose technique, a first indication that the focus detection area is selected only for the focus detection area selected as the main subject exists is displayed. The photographer can select in advance by the operation member the display mode and the second display mode in which all focus detection areas in focus as a result of the focus adjustment are displayed. When the second display mode is selected, the control device needs to perform focus detection in all focus detection regions. Therefore, accumulation by a plurality of charge accumulation times performed in the above-described embodiment and its modifications is described. The operation, that is, the sequential accumulation operation is performed. On the other hand, when the first display mode is selected, the charge accumulation time is controlled so that the luminance distribution in that region can be detected in accordance with the pixel column output on the image sensor corresponding to the selected focus detection region. To do.

  In the above-described embodiments and their modifications, all combinations of the embodiments or the embodiments and the modifications are possible.

  According to the above-described embodiment and its modification, even if there are many focus detection areas for performing focus detection, focus detection can be performed in a short time in those focus detection areas.

Cross-sectional view of a camera (imaging device) provided with a focus detection device according to an embodiment The figure which shows the structure of the focus detection optical system of one embodiment. Enlarged view of micro lens array and light receiving element array The figure for demonstrating the focus detection method of one embodiment. The figure for demonstrating the other focus detection method of one Embodiment. The block diagram which shows the detailed structure of the focus detection apparatus of one embodiment The flowchart which shows the focus detection operation | movement of one Embodiment FIG. 7 is a flowchart illustrating the focus detection operation of the embodiment, following FIG. Cross section showing a configuration of a video camera (imaging device) provided with a focus detection device of another embodiment

Explanation of symbols

1, 211; Camera body, 2, 212; Lens barrel, 14, 217; Imaging element, 15, 215; Focus detection device, 16; Control device, 21, 213; Photography lens, 52; Micro lens array, 53; Light receiving element array, 55; Memory, 56; Microcomputer, 56a; Composite signal sequence creation unit, 56b; Image shift calculation unit, 56c; Defocus amount calculation unit

Claims (5)

A microlens array in which a plurality of microlenses are arranged in a two-dimensional manner, and a light receiving element array in which a plurality of charge storage photoelectric conversion elements are arranged in a two-dimensional manner with respect to the microlens array, and passes through the optical system Light receiving means for outputting a signal obtained by receiving the received light by the light receiving element array through the microlens array;
Control means for sequentially controlling charge accumulation for a plurality of different charge accumulation times for the photoelectric conversion element arrays corresponding to each of a plurality of focus detection areas set in an image plane by the optical system;
Based on an output signal of the photoelectric conversion element array corresponding to each of the plurality of focus detection regions for each of the plurality of different charge accumulation times, focus detection of the optical system is performed, and a plurality of focus detection results and A focus detection means for calculating a plurality of reliability determination results for the focus detection results ;
Selection means for selecting a predetermined focus detection area from the plurality of focus detection areas based on the plurality of focus detection results and the plurality of reliability determination results;
Focus adjusting means for adjusting the focus of the optical system based on a focus detection result in the selected focus detection region,
After the focus adjustment of the optical system by the focus adjustment unit, the control unit gives the highest reliability determination result corresponding to the selected focus detection region among the plurality of charge accumulation times. In the charge accumulation time, the photoelectric conversion element array corresponding to the selected focus detection region is again subjected to charge accumulation control, and the focus detection unit is configured to perform the charge accumulation control again in the photoelectric conversion element array. Based on the output signal of the optical system, the focus detection of the optical system is performed again, a focus detection result is calculated, and the focus adjustment unit performs the focus adjustment of the optical system again based on the focus detection result. focusing device for. The focus adjustment apparatus according to claim 1,
Drive amount determination means for determining whether or not the drive amount of the optical system at the time of focus adjustment of the optical system by the focus adjustment means is greater than or equal to a predetermined value;
When the drive amount determination unit determines that the drive amount of the optical system is equal to or greater than the predetermined value, the control unit again performs the photoelectric conversion element corresponding to each of the plurality of focus detection regions. The charge accumulation control is sequentially performed on the column at a plurality of different charge accumulation times.
When the drive amount determination unit determines that the drive amount of the optical system is less than the predetermined value, the control unit performs the charge accumulation control again, and the focus detection unit performs the refocusing operation. performs detection, the focusing means focusing device which is characterized in that the focusing of the back. In focusing device according to claim 1 or 2,
Photometric means for measuring light transmitted through the optical system ;
The focus adjustment apparatus, wherein the control means determines the plurality of charge accumulation times based on a photometric result obtained by the photometric means. The focus adjustment apparatus according to any one of claims 1 to 3,
An imaging apparatus comprising: an imaging unit that captures an image by the optical system. The imaging apparatus according to claim 4 ,
A storage means for storing a first plurality of charge accumulation times and a second plurality of charge accumulation times as the plurality of different charge accumulation times;
The imaging means is capable of continuously capturing the image;
The control means selects one of the first and second plurality of charge accumulation times based on the output of the light receiving element array when a predetermined number of images are continuously captured, and the predetermined number of images An image pickup apparatus, wherein charge accumulation control is performed in the plurality of selected charge accumulation times during imaging after imaging.

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