JP6660036B2 - Focus detection device and imaging device - Google Patents

Description

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

  Conventionally, focus detection areas are grouped according to the brightness of each of a plurality of focus detection areas, and charges (signals) read from the line sensor are determined based on the brightness of the group having the largest number of focus detection areas belonging to the same group. ) Is proposed (refer to Patent Document 1).

JP 2012-63449 A

  In the focus detection device of Patent Document 1, when the gain is determined based on the group on the high-luminance side, sufficient output level signal data is obtained in the focus detection area of that group. However, in the focus detection areas of the other groups, the output level is significantly lower than the saturation level of the line sensor. Therefore, when the contrast of the subject is low, signal data of an appropriate output level cannot be obtained.

  An object of the present invention is to provide a focus detection device and an imaging device that can set an appropriate accumulation time.

A focus detection device according to an aspect of the invention includes an imaging element that captures a subject image formed by an optical system having a focus lens, and an imaging device that is disposed within a range that captures a subject image formed by the optical system, for a set time. a plurality of detector that outputs a signal based on the electric charge produced by photoelectric conversion of light from the object, first object image of said object image is arranged within a range to be formed the A selection unit that selects a detection unit, and a charge amount that is generated with respect to the saturation charge amount of the detection unit when a plurality of times are set based on the charge that is generated in the first time of the detection unit. Is calculated by each of the detection units selected by the selection unit, the number of the detection units whose calculated ratio is within a predetermined range is calculated for each of the plurality of times, and the calculated detection unit Generate charge based on number A time calculating unit for determining a second time to perform, the second based on the signal output from the detecting unit based on the charge generated by the time position and the imaging device in which the subject image is formed And a detection unit for detecting the amount of deviation from the above.

  According to the present invention, it is possible to provide a focus detection device and an imaging device capable of setting an appropriate accumulation time.

FIG. 2 is a schematic configuration diagram of a camera 1 according to the first embodiment. FIG. 3 is a conceptual diagram showing a configuration of a phase difference AF detection area 151 in a phase difference AF detection unit 15. FIG. 3 is a conceptual diagram showing line sensors S1 to S7 arranged corresponding to AF areas in each row. 6 is a flowchart showing a processing procedure when the control device 30 performs an AF operation of the camera 1. 5 is a flowchart illustrating a processing procedure of AF sensor control by the AF-CCD control unit 31 according to the first embodiment. 5 is a flowchart illustrating a processing procedure of AF sensor control by the AF-CCD control unit 31 according to the first embodiment. It is a flow chart which shows the processing procedure of AF sensor control by AF-CCD control part 31A of a 2nd embodiment. It is a flow chart which shows the processing procedure of AF sensor control by AF-CCD control part 31A of a 2nd embodiment.

  Hereinafter, embodiments of a focus detection device and an imaging device according to the present invention will be described with reference to the drawings. Here, an embodiment in which the focus detection device according to the present invention is applied to a camera 1 as an imaging device will be described.

[First Embodiment]
First, the camera 1 according to the first embodiment will be described. FIG. 1 is a schematic configuration diagram of a camera 1 according to the first embodiment.

  As shown in FIG. 1, the camera 1 includes a camera body 10 and an imaging lens 20 configured to be detachable from the camera body 10. The camera 1 of the present embodiment is a so-called digital single-lens reflex camera.

  The camera body 10 includes an image sensor 11, a quick return mirror 12A, a sub mirror 12B, a finder optical system 13, a photometry unit 14, a phase difference AF detection unit 15 as a focus detection sensor and a detection unit, and an operation member. 16 and a control device 30.

  The imaging device 11 is configured by a solid-state imaging device such as a CCD or a CMOS that outputs a charge converted from subject light as a charge signal. Pixels corresponding to red (R), green (G), and blue (B) are arranged in the image sensor 11 in a predetermined arrangement pattern. The imaging element 11 captures image information of an image plane formed by the imaging optical system of the imaging lens 20 and outputs the image information to the control device 30 as an image signal corresponding to color information and luminance information corresponding to each pixel.

  The quick return mirror 12A is a reflecting member configured to be movable to two different positions in the camera 1. That is, the quick return mirror 12A is movable between an operation position (see FIG. 1) interposed in the optical path from the imaging optical system of the imaging lens 20 to the image sensor 11 and a retracted position not interposed in the optical path. It is configured. The quick return mirror 12A reflects the incident light beam to the finder optical system 13 (finder screen 13A) at the operation position. A semi-transmissive region that transmits a part of the incident light beam is formed in a part of the quick return mirror 12A.

  The sub mirror 12B is a reflecting member provided on the back side of the quick return mirror 12A. The sub-mirror 12B reflects the incident light flux transmitted through the semi-transmissive area of the quick return mirror 12A toward the phase difference AF detection unit 15 in the quick return mirror 12A moved to the operation position.

  The finder optical system 13 includes a finder screen 13A, a pentaprism 13B, and an eyepiece 13C.

  The finder screen 13A is provided at a position optically equivalent to the image pickup device 11. The incident light flux guided by the quick return mirror 12A forms an image on the finder screen 13A. The pentaprism 13B and the eyepiece 13C are an optical system that enables a photographer to visually recognize a subject image formed on the finder screen 13A as an erect image.

  The photometric unit 14 includes a photometric lens 14A and a photometric sensor 14B. The photometric lens 14A guides the subject image formed on the finder screen 13A via the pentaprism 13B to the photometric sensor 14B. In the photometric sensor 14B, similarly to the image sensor 11, pixels corresponding to red (R), green (G), and blue (B) are arranged in a predetermined array pattern, and an image is formed by a lens optical system. The image information of the image plane is captured.

  Then, the photometric sensor 14B outputs a photometric signal corresponding to color information and luminance information corresponding to each pixel to the control device 30. The control device 30 detects the brightness of the imaging surface based on the photometric signal from the photometric sensor 14B, and determines the exposure.

  The operation member 16 includes various switches (not shown) for operating the camera 1. For example, the operation member 16 includes a mode selection switch for selecting an operation mode of the camera 1, an area selection switch for selecting an AF area (described later), and an instruction for starting focus adjustment (AF) and photographing. A release button and the like are included.

  The phase difference AF detection unit 15 includes line sensors S1 to S7 (described later) as focus detection sensors. The incident light flux transmitted through the semi-transmission area of the quick return mirror 12A and reflected by the sub-mirror 12B enters the line sensors S1 to S7. Further, the phase difference AF detection unit 15 transmits the electric charges detected by the line sensors S1 to S7 to the AF-CCD control unit 31 as signal data controlled by a preset accumulation time and gain as a function of a detection unit. Output.

  FIG. 2 is a conceptual diagram showing a configuration of the phase difference AF detection area 151 in the phase difference AF detection unit 15. As shown in FIG. 2, in the phase difference AF detection area 151, a plurality of AF areas (distance measurement areas) 153 as focus detection areas are provided at predetermined positions of the imaging area 152. In the present embodiment, one focus detection range (row) is configured by five AF areas 153 arranged in the vertical direction. The focus detection ranges are arranged in seven rows, and a total of 35 AF areas 153 are arranged. Hereinafter, the AF area 153 shown in FIG. 2 is also referred to as “AF area” as appropriate.

  FIG. 3 is a conceptual diagram showing line sensors S1 to S7 (hereinafter, also collectively referred to as “line sensors S”) arranged corresponding to the AF areas in each row. The line sensors S1 to S7 are arranged so as to correspond to the focus detection ranges of each row.

  In FIG. 2, each of the areas A to E shown by broken lines indicates the vertical position of the focus detection area. Each AF area 153 can be represented by a line sensor S number (1 to 7) and a region code (A to E). For example, the AF area 153 at the center of the phase difference AF detection area 151 is “C1”.

  The line sensor S is a charge storage type photoelectric conversion element array (such as a CCD line sensor) in which a plurality of photoelectric conversion elements that output charge signals according to the intensity of subject light are arranged in a line. In the line sensor S, one photoelectric conversion element is arranged in an area corresponding to each AF area. A light beam that has passed through different regions of the imaging lens 20 (see FIG. 1) and has been split into two (a pair) has been split into two by an aperture mask (not shown), and then a pair of subject images have been Are re-imaged in the corresponding area of Then, the line sensor S detects the luminance of the formed subject image as electric charge. That is, the line sensor S accumulates electric charge proportional to the luminance of the pair of subject images over the set accumulation time. As a result, a charge signal corresponding to the luminance of the pair of subject images is output from the line sensor S. The charge signal output from the line sensor S is amplified by a predetermined gain in an amplifier circuit (not shown), and then converted into digital signal data in an A / D converter (not shown). The output level of the signal data is represented by the peak value of the charge signal times the gain.

  The control device 30 includes a CPU, a memory, and the like (not shown), and integrally controls the operation of the camera 1. Further, the control device 30 detects the brightness of the imaging surface based on the photometric signal from the photometric sensor 14B and determines the exposure.

  Further, as shown in FIG. 1, the control device 30 includes an AF-CCD control unit 31, a defocus calculation unit 32, a focus area position determination unit 33, a lens A drive amount calculation unit 34, a lens drive control unit 35, and a background area / face area extraction unit 36 are provided.

  The AF-CCD control unit 31 reads out the signal data from the phase difference AF detection unit 15 and outputs the signal data to the defocus calculation unit 32. The charge accumulation time of the line sensor S of the phase difference AF detection unit 15 and the gain of the amplifier circuit are set by the AF-CCD control unit 31.

  The AF-CCD control unit 31 calculates the saturation time of each AF area to be controlled based on the previously set accumulation time of the AF area to be controlled, as a function of the saturation time calculation means.

  As a function of the accumulation time control means, the AF-CCD control unit 31 determines a saturation level range (described later) as a main luminance distribution of the focus detection range based on the saturation time of each AF area calculated in the above control. Then, the accumulation time in the accumulation control is set according to the saturation level range.

  Each control of the AF-CCD control unit 31 will be described later. In the present embodiment, the phase difference AF detection unit 15 and the AF-CCD control unit 31 constitute a focus detection device according to the present invention.

  The defocus calculation unit 32 calculates a defocus amount indicating a focus adjustment state (a defocus amount) of the imaging lens 20 based on the signal data output from the AF-CCD control unit 31.

  The focus area position determination unit 33 determines an AF area 153 in which the imaging lens 20 is finally focused based on the defocus amount calculated by the defocus calculation unit 32.

  The lens drive amount calculation unit 34 determines the focal point of the imaging lens 20 based on the defocus amount calculated by the defocus calculation unit 32 corresponding to the AF area determined by the user or the focus area position determination unit 33. The driving amount of the adjusting lens (lens group L2) is calculated.

  Here, the lens drive amount is calculated by calculating the lens target position which is the target of the drive position of the focusing lens (lens group L2). The lens target position corresponds to the position of the focus adjustment lens (lens group L2) where the defocus amount becomes substantially zero.

  The lens drive control unit 35 controls the drive of the lens drive motor 22 of the imaging lens 20 based on the lens drive amount calculated by the lens drive amount calculation unit 34, that is, the lens target position with respect to the focus adjustment lens (the lens group L2). Output a signal. In response to the drive control signal, the lens drive motor 22 drives the focus adjustment lens (lens group L2) to move it to the lens target position, thereby performing focus adjustment.

  The background area / face area extraction unit 36 extracts a high luminance portion serving as a background area from the imaging area 152 based on the signal data output from the AF-CCD control unit 31. The background area / face area extraction unit 36 extracts a face area from the signal data output from the AF-CCD control unit 31 by a method such as pattern matching.

  The imaging lens 20 includes a plurality of lens groups L1, L2, and L3 constituting an imaging optical system and a lens driving motor 22 inside a lens barrel 21. The lens group L2 is a focus adjusting lens that can move in the direction of the optical axis OA to adjust the image forming position. The lens group L2 is configured to be movable toward the subject or the image sensor 11 along the optical axis OA by the lens driving motor 22. The driving of the lens driving motor 22 is controlled by a control device 30 provided on the camera body 10 side.

  Next, a description will be given of a processing procedure when the AF operation is performed in the camera 1 configured as described above. FIG. 4 is a flowchart illustrating a processing procedure when the control device 30 performs the AF operation of the camera 1. The process of this flowchart is started when the user performs an operation such as half-pressing the release button (the operation member 16) and instructs the camera 1 to perform AF driving.

  In step S101 shown in FIG. 4, the AF-CCD control unit 31 causes the phase difference AF detection unit 15 (line sensor S) to execute charge accumulation control as AF sensor control. The signal data obtained by the accumulation control is output from the phase difference AF detection unit 15 to the defocus calculation unit 32 via the AF-CCD control unit 31.

  In step S102, based on the signal data output from the AF-CCD control unit 31, the defocus calculation unit 32 obtains an image shift amount by a correlation calculation, and calculates a defocus amount.

In step S103, the focus area position determining unit 33 executes a routine (not shown) for determining the AF area position.
In step S104, the lens drive amount calculation unit 34 executes a lens drive amount calculation routine (not shown).

  In step S105, the lens drive control unit 35 outputs a drive control signal to the lens drive motor 22 of the imaging lens 20 according to the result of the lens drive amount calculation of the lens drive amount calculation unit 34 in step S104.

  Next, the AF sensor control (subroutine) in step S101 of FIG. 4 will be described. FIGS. 5 and 6 are flowcharts showing a processing procedure of AF sensor control by the AF-CCD control unit 31. The processing of the flowcharts shown in FIGS. 5 and 6 is executed for each of the line sensors S1 to S7. Here, a description will be given as processing of an arbitrary line sensor S.

  In step S201 shown in FIG. 5, the AF-CCD control unit 31 determines whether the line sensor S has been activated. In this step S201, if the determination of the AF-CCD control unit 31 is "YES", the process proceeds to step S203. In step S201, if the determination of the AF-CCD control unit 31 is “NO”, the process proceeds to step S202.

In step S202, the AF-CCD control unit 31 executes a startup process such as initialization.
In step S203, the AF-CCD control unit 31 calculates each saturation time of the AF area to be controlled based on the previously set accumulation time of the AF area to be controlled.

  If the background area exclusion mode has been set in advance, the background area / face area extraction unit 36 (see FIG. 1) performs an AF area (focus detection) to be excluded from control as pre-processing of step S203. Area) is set. That is, when there is a high-brightness part serving as a background area from the imaging area 152 (see FIG. 2), the background area / face area extraction unit 36 excludes the corresponding AF area from the control target and excludes the remaining AF areas. The area is to be controlled.

  In step S204, the AF-CCD control unit 31 sets the AF area in which the saturation time is the shortest as the AF area with the highest luminance, and sets the ratio of the saturation time in the other AF area to the ratio Hb% of the saturation time (hereinafter referred to as Hb%). , "Saturation time ratio"). Then, the AF-CCD control unit 31 sets the calculated saturation time ratio (%) in a range of a predetermined saturation time ratio Hbmin (%) to Hbmax (%) (hereinafter, also referred to as a “saturation level range”). Count the number of areas to enter.

Here, a description will be given with reference to Table 1 below. In Table 1, in the focus detection range corresponding to the line sensor S1 (see FIG. 3), the corresponding AF areas (focus detection areas) are represented by A1, B1, C1, D1, and E1.

  As shown in Table 1, in the focus detection range corresponding to the line sensor S1, the AF area with the shortest saturation time (the AF area with the highest luminance) is B1 (5 ms). Here, assuming that the ratio Hb% of the saturation time in B1 is 85% (5 ms × 0.85 = 4.25 ms), the saturation time ratio in another AF area (the ratio based on 4.25 ms of 85%) ) Is 15.2% to 53.1%. If the saturation level range set for the AF area with the highest luminance is 25% (Hbmin) to 85% (Hbmax), the number of areas falling within this saturation level range is three areas A1, B1, and C1. Becomes

  In the present embodiment, the upper limit (Hbmax) of the saturation level range set for the AF area with the highest luminance is set to be equal to or less than the saturation level (100%) of the line sensor S in order to reduce the influence of overflow. . This embodiment shows an example in which Hbmax is set to 85%.

  In step S205, the AF-CCD control unit 31 sets the AF area having the longest saturation time as the AF area with the lowest luminance, and the ratio of the saturation time Hd% to the saturation time ratio (%) in another AF area. Is calculated. Then, the AF-CCD control unit 31 counts the number of AF areas where the calculated saturation time ratio (%) falls within a saturation level range of a preset saturation time ratio Hdmin (%) to Hdmax (%).

  As shown in Table 1, in the focus detection range corresponding to the line sensor S1, the AF area where the saturation time is the longest (the AF area with the lowest luminance) is E1 (28 ms). Here, assuming that the saturation time ratio Hd% in E1 is 25% (28 ms × 0.25 = 7 ms), the saturation time ratio in other AF areas (the ratio based on 7 ms of 25%) is 35%. 0.0% to 140.0%. Assuming that the saturation level range set for the AF area with the lowest luminance is 25% (Hdmin) to 100% (Hdmax), the number of areas falling within this saturation level range is A1, C1, D1, and E1. There are four areas.

  In the present embodiment, the lower limit (Hdmin) of the saturation level range set for the AF area with the lowest luminance is set to be equal to or higher than the noise level of the line sensor S as a focus detection sensor in order to reduce the influence of noise. Is done. This embodiment shows an example in which Hdmin is set to 25%.

  In step S206, the AF-CCD control unit 31 sets an AF area which is an intermediate area of the saturation time (an intermediate area between the shortest saturation time and the longest saturation time) as an AF area of intermediate luminance, and sets a ratio Hc of the saturation time to the AF area. %, The saturation time ratio (%) in the other AF area is calculated. Then, the AF-CCD control unit 31 counts the number of AF areas where the calculated saturation time ratio (%) falls within a saturation level range of a preset saturation time ratio Hcmin (%) to Hcmax (%).

  As shown in Table 1, in the focus detection range corresponding to the line sensor S1, the AF area that is an intermediate region of the saturation time is C1 (12 ms). Here, assuming that the ratio Hc% of the saturation time in C1 is 50% (12 ms × 0.5 = 6 ms), the saturation time ratio in other AF areas (the ratio based on 6 ms of 50%) is 21%. 0.4% to 120.0%. If the saturation level range set for the intermediate brightness AF area is 25% (Hcmin) to 100% (Hcmax), the number of areas falling within this saturation level range is A1, C1, D1, and A3. Area.

  In step S207 shown in FIG. 6, the AF-CCD control unit 31 sets the saturation level range including the largest saturation time ratio of the AF area (A1, B1, C1, D1, E1) among the three saturation level ranges. (Saturation level range of the maximum count number) is specified as a saturation level range that is a main luminance distribution of the focus detection range corresponding to the line sensor S1. Then, the AF-CCD control unit 31 sets a saturation time which is a reference of the specified saturation level range as an accumulation time in the current control.

  In the present embodiment, of the three saturation level ranges, the saturation level range in which the saturation time ratio of the AF areas (A1, B1, C1, D1, E1) is the largest is the AF area with the lowest luminance of 4 areas. Corresponding Hdmin (%) to Hdmax (%). Therefore, the AF-CCD control unit 31 sets the saturation level range of Hdmin (%) to Hdmax (%) corresponding to the AF area having the lowest luminance as the main luminance distribution of the focus detection range corresponding to the line sensor S1. Specify as a level range. Then, the AF-CCD control unit 31 sets the saturation time 7 ms (see Table 1) as a reference of the specified saturation level range as the accumulation time in the current control.

  In step S207, if there is a plurality of saturation level ranges that include the largest number of AF areas in step S207, the AF-CCD control unit 31 selects the saturation level range on the higher luminance side. I do. For example, as the saturation level range that includes the most AF areas, the saturation level range of Hdmin (%) to Hdmax (%) corresponding to the AF area with the highest luminance and the Hcmin (%) to Hdmax (%) corresponding to the AF area with the intermediate luminance It is assumed that there is a saturation level range of Hcmax (%). In this case, the AF-CCD control unit 31 selects a saturation level range from Hdmin (%) to Hdmax (%) corresponding to the AF area with the highest brightness, which is a saturation level range on the higher brightness side.

  In step S208 shown in FIG. 6, the AF-CCD control unit 31 sets a gain for the line sensor S of the phase difference AF detection unit 15 based on the result of the previous accumulation control. Here, it is desirable to set the gain as low as possible in order to reduce the noise of the output signal data. However, if there is a limit on the accumulation time during continuous shooting, etc., the gain is set according to the upper limit of the accumulation time.

In step S209, the AF-CCD control unit 31 resets the accumulation time set in step S207 according to the gain set in step S208.
In step S210, the AF-CCD control unit 31 controls the accumulation of the line sensor S according to the accumulation time reset in step S209. In this accumulation control, electric charges are accumulated in the line sensor S according to the set accumulation time. The electric charge accumulated in the line sensor S is transferred to the amplifier circuit as an electric charge signal, and is amplified with a preset gain. The charge signal amplified by the amplifier circuit is further converted to digital signal data by the A / D converter.

In step S211, the AF-CCD control unit 31 reads out the signal data output from the phase difference AF detection unit 15, performs correction processing such as sensitivity nonuniformity correction, and outputs the signal data to the defocus calculation unit 32.
After the end of this subroutine, the process of the AF-CCD control section 31 proceeds to step S102 of the main routine shown in FIG.

According to the focus detection device of the first embodiment described above, the following effects can be obtained.
In the focus detection device according to the first embodiment, the saturation level range that is the main luminance distribution of the focus detection range is specified based on the saturation time of each AF area, and the accumulation level in the accumulation control is determined according to the saturation level range. The time is set. According to this, in as many focus detection areas as possible in each focus detection range, it is possible to set an accumulation time that is less affected by overflow and noise. Therefore, according to the focus detection device of the first embodiment, when performing accumulation control of a plurality of focus detection areas based on one accumulation time, an appropriate accumulation time is set in as many focus detection areas as possible. can do.

  In the focus detection device according to the first embodiment, the saturation level range including the largest saturation time ratio of the AF area among a plurality of preset saturation level ranges is the main luminance distribution of the focus detection range. Specified as the saturation level range. According to this, it is possible to specify the saturation level range most suitable for the luminance distribution of the captured image. Therefore, according to the focus detection device of the first embodiment, it is possible to set a more appropriate accumulation time that is less affected by overflow and noise in each focus detection range.

  In the focus detection device according to the first embodiment, when there are a plurality of saturation level ranges that include the AF area most among a plurality of saturation level ranges, a saturation level range on a higher luminance side is selected. . Therefore, according to the focus detection device of the first embodiment, signal data with a higher output level can be obtained while suppressing overflow in as many focus detection areas as possible.

[Second embodiment]
Next, a camera 1A according to a second embodiment will be described. The basic configuration of the camera 1A according to the second embodiment is the same as that of the camera 1 according to the first embodiment (see FIG. 1), and a description thereof will be omitted.

  The AF-CCD control unit 31A (see FIG. 1) of the second embodiment changes the saturation level ranges of high luminance, low luminance, and intermediate luminance according to the set gain. Specifically, the AF-CCD control unit 31A temporarily sets the gain of each AF area, and if there is at least one AF area where the temporarily set gain becomes High, the lower limit value of each saturation level range is set higher. Change to become. Other processes are the same as those in the first embodiment, and thus description thereof is omitted.

  FIG. 7 and FIG. 8 are flowcharts showing a processing procedure of AF sensor control by the AF-CCD control unit 31A of the second embodiment. The processing of steps S301 to S303 shown in FIG. 7 corresponds to the processing of steps S201 to S203 shown in FIG. Further, the processing of steps S307 to S314 shown in FIG. 8 corresponds to the processing of steps S204 to S206 shown in FIG. 5 and steps S207 to S211 shown in FIG. Hereinafter, steps S304 to S306 shown in FIG. 7 will be mainly described as processes characteristic of the present embodiment, and description of processes overlapping with the processes of the above-described first embodiment will be omitted.

  In step S304 shown in FIG. 7, the AF-CCD control unit 31A temporarily sets the gain of each AF area based on the saturation time of each AF area to be controlled calculated in step S303. In this provisional setting, based on the previously set gain and accumulation time, it is set after estimating how much gain should be set to appropriately control the signal data. In the present embodiment, it is assumed that the gain can be set in three stages of Low, Middle (> Low), and High (> Middle) in an amplifier circuit (not shown) of the phase difference AF detection unit 15.

  In step S305, the AF-CCD control unit 31A determines whether there is an AF area in which the temporarily set gain becomes High. In this step S305, if the determination of the AF-CCD control section 31 is "YES", the process proceeds to step S306. If it is determined in step S305 that the AF-CCD control unit 31 determines “NO”, the process proceeds to step S307 (see FIG. 8).

  In step S306, the AF-CCD control unit 31A changes so that the lower limit value of the saturation level range used in the subsequent processing of steps S307 to S309 (corresponding to steps S204 to S206 in FIG. 5) becomes higher. In the present embodiment, the AF-CCD control unit 31A changes Hbmin, Hdmin, and Hcmin from 25% to 35%. In step 306, the ratio Hd% of the saturation time in the AF area where the saturation time is the longest is changed from 25% to 35%.

  When the lower limit value of the saturation level range is changed in step S306, as shown in FIG. 8, the saturation level range in step S307 is 35% (Hbmin) to 85% (Hbmax). Further, the saturation level range in step S308 is 35% (Hdmin) to 100% (Hdmax). The saturation level range in step 308 is calculated based on a saturation time ratio of 35%. Further, the saturation level range in step S309 is 35% (Hcmin) to 100% (Hcmax). If the determination in step S305 is NO and the process in step S306 is skipped, the lower limit value of the saturation level range in steps S307 to S309 remains at 25% (set value in the first embodiment).

Here, the setting of the accumulation time in the second embodiment will be described with reference to Table 2 below. The AF areas (A1 to E1) shown in Table 2 indicate the focus detection ranges corresponding to the line sensor S1 as in Table 1 (first embodiment).

  As shown in Table 2, in the focus detection range corresponding to the line sensor S1, the AF area with the shortest saturation time (the AF area with the highest luminance) is B1 (2 ms). Here, since the saturation time ratio Hb% in B1 is 85% (2 ms × 0.85 = 1.7 ms), the saturation time ratio in another AF area (based on the 85% of 1.7 ms). Ratio) is 3.4% to 85.0%. If the saturation level range set for the AF area with the highest luminance is 35% (Hbmin) to 85% (Hbmax), the number of areas falling within the saturation level range is one area of B1.

  Further, as shown in Table 2, in the focus detection range corresponding to the line sensor S1, the AF area where the saturation time is the longest (the AF area with the lowest luminance) is E1 (50 ms). Here, since the ratio Hd% of the saturation time in E1 is 35% (50 ms × 0.35 = 17.5 ms), the saturation time ratio in another AF area (based on 17.5 ms of 35%). Ratio) is 35.0% to 875.0%. If the saturation level range set for the AF area with the lowest luminance is 35% (Hdmin) to 100% (Hdmax), the number of areas falling into this saturation level range is three areas C1, D1, and E1. Becomes

  Further, as shown in Table 2, in the focus detection range corresponding to the line sensor S1, the AF area which is an intermediate region of the saturation time is C1 (18 ms). Here, since the saturation time ratio Hc% in C1 is 50% (18 ms × 0.5 = 9 ms), the saturation time ratio in other AF areas (the ratio based on 9 ms of 50%) is: It becomes 18.0%-450.0%. If the saturation level range set for the intermediate brightness AF area is 35% (Hcmin) to 100% (Hcmax), the number of areas falling within this saturation level range is A1, C1, and D1. Becomes

  In the present embodiment, of the three saturation level ranges, the saturation level range in which the saturation time ratio of the AF areas (A1, B1, C1, D1, and E1) is the largest is the AF area having the minimum luminance of 3 areas. Hdmin (%) to Hdmax (%) corresponding thereto, and Hcmin (%) to Hcmax (%) corresponding to the AF area of medium brightness of 3 areas. As described above, when there are a plurality of saturation level ranges that include the largest number of AF areas, the saturation level range on the higher luminance side is selected. Therefore, the AF-CCD control unit 31A sets the saturation level range from Hcmin (%) to Hcmax (%) corresponding to the intermediate brightness AF area to the saturation that is the main brightness distribution of the focus detection range corresponding to the line sensor S1. Specify as a level range. Then, the AF-CCD control unit 31A sets the saturation time 9 ms (see Table 2) as a reference of the specified saturation level range as the accumulation time in the current control.

According to the focus detection device of the second embodiment described above, the following effects can be obtained.
In the focus detection device according to the second embodiment, if there is at least one AF area where the temporarily set gain is High, the lower limit of each saturation level range is changed to be higher. In general, when the brightness of the subject is extremely low, the accumulation time is long, and thus the luminance may not be within the set accumulation time. Therefore, when there is an AF area where the temporarily set gain is High, that is, when there is an AF area with extremely low luminance, the lower limit value of each saturation level range is increased to increase the saturation on the high luminance side. Since the number of AF areas that fall into the low-luminance or middle-range saturation level range is larger than the number of AF areas that fall into the level range, the accumulation time corresponding to the low-brightness or middle-range saturation level range is set. . Therefore, according to the focus detection device of the second embodiment, when performing accumulation control of a plurality of focus detection areas based on one accumulation time, even if a captured image includes a dark subject, In the focus detection area, an appropriate accumulation time can be set.

[Modification]
Without being limited to the embodiment described above, the present invention can be variously modified and changed as described below, and these are also within the scope of the present invention.

  In step S207 shown in FIG. 6, when the AF area (A1, B1, C1, D1, E1) includes a face detection area or an area to be prioritized (hereinafter, also collectively referred to as a "priority area") , The number of these priority areas may be counted, and the saturation level range with the largest number of counts may be selected based on the priorities of steps S204> S205> S206 shown in FIG.

  In the mode in which the priority areas are set as described above, if these priority areas are not counted, the line sensor uses the accumulation time set by the other line sensors whose priority areas are counted. As described above, the accumulation time in the mode in which the priority area is set is preferably set to a time during which the overflow is unlikely to occur, such as the calculated saturation time × 0.5.

  In addition, the above-described embodiments and modified embodiments can be appropriately combined and used. However, since the configuration of each embodiment is clear from the drawings and the description, the detailed description is omitted. Furthermore, the present invention is not limited by the embodiments described above.

  1, 1A: camera, 10: camera body, 11: imaging element, 15: phase difference AF detection unit, 20: imaging lens, 30: control device, 31, 31A: AF-CCD control unit, 32: defocus calculation unit , 33: focus area position determination unit, 34: lens drive amount calculation unit, 35: lens drive control unit, 36: background area / face area extraction unit

Claims (8)

An image sensor that captures a subject image formed by an optical system having a focus lens;
A plurality of detection units arranged within a range for capturing a subject image formed by the optical system and outputting a signal based on electric charges generated by photoelectrically converting light from the optical system for a set time ; When,
A selection unit that selects the detection unit arranged within a range where a first subject image is formed among the subject images;
When a plurality of times are set based on the charge generated by the detection unit during the first time , the selection unit selects the ratio of the amount of charge generated to the amount of saturation charge of the detection unit. Calculated by each of the detection units, the number of the detection units whose calculated ratio is within a predetermined range is calculated for each of the plurality of times, and the generation of electric charge is performed based on the calculated number of the detection units. A time calculator for determining a second time to be performed;
A detection unit that detects a shift amount between a position where the subject image is formed and the imaging element based on a signal output from the detection unit based on the charge generated in the second time ;
Focus detection device having   The focus detection device according to claim 1,
  The focus detection device, wherein the plurality of times are calculated by the detection unit selected by the selection unit based on charges generated in a first time.   The focus detection device according to claim 1,
  The focus detection device, wherein each of the plurality of times is a time calculated based on a maximum value and a minimum value of the electric charge generated in the first time and a value therebetween.   The focus detection device according to claim 1,
  The time calculation unit determines the second time based on the time when the number of the detection units in which the ratio is within a predetermined range is the largest among the plurality of times,
  Focus detection device. In the focus detection device according to any one of claims 1 to 4 ,
The time calculation unit does not use a signal output from the detection unit disposed in a range of a background of the first subject image for calculation of the second time .
Focus detection device. The focus detection device according to any one of claims 1 to 5,
The first subject image is a face;
Focus detection device. The focus detection device according to any one of claims 1 to 6 ,
The predetermined range is a range corresponding to a range in which the generated charge amount is larger than the noise value and smaller than the saturation charge amount of the detection unit.
Focus detection device.   An imaging apparatus comprising the focus detection device according to claim 1.

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