JP2012027367A - Focus detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focus detector with which the pixel arrangement corresponding to the dense focal position in the imaging area can be performed and the monitoring region of the focal detection processing can be flexibly selected even in the multiple focal detection system.SOLUTION: A camera system according to the present invention has a focal detection mechanism which sets the detection area of pixel output respectively for a plurality of pixel columns in a area sensor position 27, makes the maximum detection circuits C1 to C14 select the pixel output corresponding to the detection range set from the pixel output of the pixel columns of the area sensor position 27 as valid signals, and controls the pixel accumulation of each pixel columns by detecting the output of pixels selected by the maximum detection circuits C1 to C14 as valid signals.

Description

  The present invention relates to a focus detection apparatus provided in an imaging apparatus, for example.

  Regarding the camera focus detection method, the TTL position that detects the defocus amount of the photographing lens by guiding the light beam that has passed through the photographing lens onto a pair of photoelectric conversion elements and performing focus detection calculation including integration control on the output of the light beam. In general, the phase difference automatic focus detection (AF) method is widely used in single-lens reflex cameras. In addition, recent single-lens reflex cameras generally perform focus detection or distance measurement in a plurality of focus detection areas in the imaging area.

  In order to realize such a plurality of distance measuring points, photoelectric conversion element arrays composed of a plurality of pixels are densely arranged. In order to control each of the plurality of photoelectric conversion element arrays with an accumulation time optimum for distance measurement, it is necessary to perform accumulation control for each line (for each photoelectric conversion element array).

  Here, in order to perform integration control efficiently and accurately, a plurality of pixels corresponding to a part of one line are arranged as monitor pixels, apart from pixels corresponding to all one line, There has been proposed a focus detection device that selectively controls accumulation (see, for example, Patent Document 1).

  Further, there is a focus detection device that performs accumulation control using all pixels in one line when mounted on a single-lens reflex camera, and using only some pixels of one line when mounted on a lens shutter camera. It has been proposed (see, for example, Patent Document 2).

Japanese Patent Application Laid-Open No. 9-121311 Japanese Patent Laid-Open No. 10-39203

  However, in the device described in Patent Document 1, a plurality of pixels corresponding to a part of one line other than the pixels for one line are arranged, so that a width of one line or more is necessary, and the pixel arrangement is not efficient. Absent. In addition, the device described in Patent Document 2 uses a register to change monitor pixels in accordance with the AF method of the mounted camera, and cannot be applied to a multipoint AF sensor as it is.

  Further, in any of those described in Patent Documents 1 and 2, it is not possible to realize a pixel arrangement corresponding to a focus position that is densely arranged in the photographing screen. In addition, as the monitor pixels for accumulation control, it is only possible to set all the pixels in one line or only some of the predetermined pixels.

  The present invention has been made in view of the above, and enables a pixel arrangement corresponding to a dense in-focus position in a photographing screen, and also provides a monitor range for focus detection processing even in a multi-point in-focus detection method. An object of the present invention is to realize a focus detection device that can be selected flexibly.

  In order to solve the above-described problems and achieve the object, a focus detection apparatus according to the present invention includes an area sensor having a plurality of pixel columns each including a plurality of pixels, and detects an output of the pixel for each pixel column. Then, in a focus detection device that performs accumulation control of pixels included in the pixel column and performs focus detection based on the detected output of the pixel, a detection range of pixel output is provided for each of the plurality of pixel columns of the area sensor. A detection range setting means for setting, a detection range control means for selecting an output of a pixel corresponding to the detection range set by the detection range setting means as an effective signal, and an output of the pixel selected by the detection range control means as an effective signal And accumulation control means for controlling accumulation of pixels in the pixel column.

  The focus detection apparatus according to the present invention includes a switch for electrically connecting or disconnecting the pixel and the accumulation control unit for each pixel under the control of the detection range control unit. To do.

  In addition, the focus detection apparatus according to the present invention can set manual selection or automatic selection of the focus target position, and the detection range setting means can detect the previous time detected by the most recent focus detection when the manual selection is set. A detection range is set according to the focus amount.

  In the focus detection apparatus according to the present invention, the detection range setting means may be a predetermined region that includes a focus target position in the pixel row when the absolute value of the previous defocus amount is smaller than a predetermined value. The standard detection region is set as the detection range, and when the absolute value of the previous defocus amount is larger than a predetermined value, a range wider than the standard detection region is set as the detection range.

  In the focus detection apparatus according to the present invention, when the absolute value of the previous defocus amount is larger than a predetermined value, the detection range setting unit adds a pixel region corresponding to the previous defocus amount to the standard detection region. The region is set as the detection range.

  The focus detection apparatus according to the present invention can set manual selection or automatic selection of a focus target position, and the detection range setting means outputs an output result of all pixels of the area sensor when the automatic selection is set. And a range occupied by the main subject to be focused is detected, and the range occupied by the detected main subject is set as the detection range.

  In the focus detection apparatus according to the present invention, the accumulation control unit accumulates the pixels in the pixel column when the maximum value among the accumulation outputs of the pixels selected by the detection range control unit exceeds a predetermined value. It is characterized by terminating.

  According to the present invention, the detection range setting means for setting the detection range of the pixel output for each of the plurality of pixel columns of the area sensor, and the pixel corresponding to the detection range set by the detection range setting means among the pixel outputs of the pixel row A detection range control unit that selects the output of the pixel array as an effective signal, and an accumulation control unit that detects the output of the pixel selected by the monitor range control unit as the effective signal and controls the accumulation of the pixels in the pixel column. A pixel arrangement corresponding to a dense focus position in the screen can be made, and a monitor range for focus detection processing can be flexibly selected even in the multipoint focus detection method.

FIG. 1 is a block diagram including a schematic mechanism showing a configuration example around an AF of a camera system to which a multi-AF type focus detection apparatus according to an embodiment of the present invention is applied. FIG. 2 is a schematic configuration diagram showing an example of the basic configuration of the AF optical system including the AF sensor. FIG. 3 is a block diagram illustrating a configuration example of the AF controller. FIG. 4 is a schematic front view showing the arrangement of distance measuring points on the photographing screen as an example of the arrangement of multi-configuration AF sensors. FIG. 5 is a schematic front view showing an arrangement example of AF sensors on the sensor chip corresponding to the arrangement of distance measuring points. FIG. 6 is a circuit diagram showing a configuration example of the maximum value detection circuit. FIG. 7 is a diagram for explaining a monitor range for accumulation control set in the embodiment. FIG. 8 is a flowchart showing an example of the focus detection / focus correction operation executed under the control of the control unit. FIG. 9 is a schematic flowchart showing an example of a focus detection / focus correction operation executed under the control of the control unit. FIG. 10 is a flowchart showing a processing procedure of the first focus detection process shown in FIG. FIG. 11 is a flowchart illustrating a processing procedure of the second focus detection process illustrated in FIG. 9. FIG. 12 is a diagram showing an example of defocus distribution information obtained in the main subject recognition process shown in FIG. FIG. 13 is a flowchart showing a processing procedure of the third focus detection processing shown in FIG.

  Exemplary embodiments of a focus detection apparatus according to the present invention will be described below with reference to the accompanying drawings. The present invention is not limited to this embodiment, and various modifications can be made without departing from the spirit of the present invention.

(Embodiment)
FIG. 1 is a block diagram including a schematic mechanism showing a configuration example around a focus detection (AF) mechanism of a camera system to which the multi-AF focus detection apparatus of the present embodiment is applied. Here, an example in which the TTL phase difference AF method is applied to a single-lens reflex camera is shown.

  First, an interchangeable lens 10 that is detachably mounted on a camera body (not shown) includes a photographing lens 11. An in-focus state is obtained by driving the photographing lens 11 in the optical axis direction by the motor driver 12. In addition, the interchangeable lens 10 includes a lens control unit 13. The lens control unit 13 receives the defocus amount from the camera body side, calculates the driving amount of the photographing lens 11, and drives and controls the photographing lens 11 via the motor driver 12 by the driving amount.

  On the other hand, in the camera body, a main mirror 14 is provided on the optical axis of the taking lens 11. The main mirror 14 has a movable mirror configuration, and is positioned at a down position as shown in the figure during AF, and splits the light beam that has passed through the photographing lens 11 into a finder optical system 16 and an AF optical system 19. To do. The main mirror 14 retracts upward when photographing a subject, so that the total luminous flux transmitted through the photographing lens 11 is guided to the image sensor 24.

  Here, the finder optical system 16 includes an optical element such as a pentaprism as is well known. A finder screen 15 is disposed in front of the finder optical system 16, and a finder eyepiece 17 that is viewed by the photographer is disposed in the subsequent stage of the finder optical system 16.

  Further, on the rear stage side of the main mirror 14 along the optical axis direction of the photographic lens 11, all the light beams transmitted through the main mirror 14 when the main mirror 14 is located at the down position are directed to the AF optical system 19 side. A reflecting sub-mirror 18 is provided. When the main mirror 14 is retracted up, the sub mirror 18 is retracted up together with the main mirror 14 at a position where the light flux to the image sensor 24 is not blocked.

  Further, the camera body is an AF that is a photoelectric conversion element that generates a signal for focus detection by entering a light beam split by the main mirror 14 and passing through the AF optical system 19 into a pair of internal photoelectric conversion element arrays. A sensor 20 is provided. As this AF sensor 20, a multi-AF sensor having a pair of photoelectric conversion element arrays for each of a plurality of focus detection areas is used.

  Further, the camera body is provided with a control unit 21 which is a microcomputer functioning as a system controller that controls control processing and image processing of each unit including control related to AF. Lens data necessary for the calculation is transmitted from the lens control unit 13 to the control unit 21 prior to the calculation. In addition, the control unit 21 transmits a defocus amount that is an AF calculation result to the lens control unit 13.

  Further, between the AF sensor 20 and the control unit 21, an AF controller 22 having an ASIC configuration that is controlled by the control unit 21 and controls the AF sensor 20 by outputting predetermined instruction information to the AF sensor 20. Is provided.

  In FIG. 1, a two-dimensional CCD is used as the image sensor 24, but a film corresponds to a silver salt camera. A focal plane shutter 23 is provided in front of the image sensor 24.

  Next, configuration examples of the AF optical system 19 and the AF sensor 20 will be described. FIG. 2 is a schematic configuration diagram showing an example of the basic configuration of the AF optical system 19 including the AF sensor 20. Since the AF optical system 19 has a configuration of a known TTL phase difference AF optical system, it will be briefly described. When the photographic lens 11 is in focus, the light beam transmitted through the photographic lens 11 is focused on the imaging equivalent surface 31 that is a virtual surface on the front surface of the AF optical system 19, condensed and divided by the condenser lens 32, and a pair. The light beam is narrowed by the separator diaphragm 33 and imaged on the sensor arrays 35 </ b> A and 35 </ b> B which are a pair of photoelectric conversion element arrays in the AF sensor 20 by the pair of separator lenses 34. Here, a known TTL phase difference AF method for measuring the defocus amount of the photographing lens 11 by measuring the imaging interval between the pair of sensor arrays 35A and 35B is constructed.

  FIG. 3 is a block diagram illustrating a configuration example of the AF controller 22. The AF controller 22 includes a sequencer 51 that controls the operation of the AF sensor 20 under the control of the control unit 21, an A / D converter 52, a digital value holding memory 53, an AF calculation unit 54, and a timer 55. A register 56 for holding the accumulation end time, a flash ROM 57, and the like. The A / D converter 52 is for converting the analog pixel output output from the AF sensor 20 side into digital data. The memory 53 stores the data A / D converted by the A / D converter 52 and provides it for calculation of focus information. The AF calculation unit 54 calculates the defocus amount based on the signal from the AF sensor 20 converted by the A / D converter 52, the accumulation end time held in the register 56, and the like.

  FIG. 4 is a schematic front view showing an arrangement of distance measuring points on the photographing screen 25 as an arrangement example of the multi-configuration AF sensor 20. The AF sensor 20 of the present embodiment shows an application example to a multi-AF sensor having a large number of distance measuring points (focus detection areas) P of, for example, 7 × 5 = 35 points. These distance measuring points P are set as combinations of horizontal pixel columns and vertical pixel columns, respectively. In FIG. 4, in order to make the drawing easy to see, the horizontal pixel columns for 14 lines are back-projected on the photographing screen 25 and displayed. Actually, the vertical pixel column for 10 lines, like the horizontal pixel column, is not shown in FIG. 4, but can be back-projected and superimposed on the photographing screen 25.

  FIG. 5 is a schematic front view showing an arrangement example of the AF sensor 20 on the sensor chip 26 corresponding to the arrangement of one distance measuring point P shown in FIG. The sensor chip 26 includes an area sensor unit 27 that includes a plurality of pixel columns each including a plurality of pixels and receives a focus detection light beam. The area sensor unit 27 is configured by densely arranging a plurality of pixel columns.

  Specifically, the horizontal pixel column is composed of 14 lines, and the vertical pixel column is composed of 10 lines. The horizontal pixel columns for 14 lines consist of horizontal pixel column groups 28a and 28b (corresponding to F value 5.6) or horizontal pixel column groups 128a and 128b (corresponding to F value 2.8) located on the left and right. A vertical pixel column for 10 lines is composed of vertical pixel column groups 29a and 29b positioned above and below. That is, the area sensor unit 27 includes a plurality of vertical pixel column groups 29a and 29b corresponding to the focus detection light beam divided in one direction and a plurality of horizontal pixel columns corresponding to the focus detection light beam divided in the direction perpendicular to one direction. It consists of groups 28a and 28b.

  In the present embodiment, maximum value detection circuits C1 to C14 for detecting the maximum value of the pixel output are provided. The maximum value detection circuits C1 to C14 are provided corresponding to the respective lines (pixel columns), and perform accumulation control for each line. Then, as the accumulation control process, when the maximum value of the pixel output in one line becomes equal to or greater than a certain value Vth, the accumulation is terminated and an accumulation end signal TG is output.

  First, the configuration and operation of the maximum value detection circuit will be described with reference to FIG. FIG. 6 is a circuit diagram showing a configuration example of the maximum value detection circuit. The number of pixels per line is N, and the output of each pixel n in one line is Vn. Here, 1 ≦ n ≦ N. Further, the number of lines is L, and a symbol indicating which line is m. Here, 1 ≦ m ≦ L. In FIG. 6, the pixel column of line 1 and the pixel column of line L are shown as P1 and PL.

  In FIG. 6, the maximum value detection circuits C1 to CL provided on the lines 1 to L are turned on / off by the differential amplifier 61-n to which the output of each pixel n is input and the output of the differential amplifier 61-n, respectively. A common output that has a set of a MOS switch 62-n to be controlled and a voltage follower 63-n that outputs the output of the corresponding pixel n when the MOS switch 62-n is turned on is OR-connected. A differential amplifier 64 is provided on the line.

  Furthermore, in the present embodiment, as shown in FIG. 6, a control unit (line 1 monitor range control unit 65-1 to line L monitor) that selects a pixel to be monitored in each of the maximum value detection circuits C1 to CL. A selection switch 66-n is provided for each pixel between the range control unit 65-L), the MOS switch 62-n, and the differential amplifier 64. The switch 66-n has a function of electrically connecting or disconnecting each pixel and the accumulation control unit 40 under the control of the line 1 monitor range control unit 65-1 to the line L monitor range control unit 65-L. Have.

  The line 1 monitor range control unit 65-1 to line L monitor range control unit 65-L turns on the pixel selection switch 66-n corresponding to the range designated as the monitor range for accumulation control, and the control unit 21 The pixel corresponding to the set detection range and the accumulation control unit 40 are electrically connected. Then, the line 1 monitor range control unit 65-1 to the line L monitor range control unit 65-L turns off the other selection switches 66-n. As a result, only the pixels included in the monitor range instructed by the control unit 21 output Vn (m). The line 1 monitor range control unit 65-1 to the line L monitor range control unit 65-L have a function of selecting, as an effective signal, an output of a pixel corresponding to a detection range set by the control unit 21 from line pixel outputs. . Therefore, the line 1 monitor range control unit 65-1 to the line L monitor range control unit 65-L performs the on / off control of the selection switch 66-n, thereby setting the monitor range for accumulation control in each line. Each line is flexibly switched.

  Accordingly, in the present embodiment, the control unit 21 can set the monitor range of the pixel output for each of the plurality of lines of the area sensor, and can perform distance measurement calculation by freely extracting pixels within one line. It becomes possible. That is, according to the present embodiment, the monitor range for accumulation control can be freely set during the focus detection process.

  When the line 1 is taken as an example, in such a configuration, Vn (1) input to the maximum value detection circuit C1 from the pixel n in which the switch 66-n is turned on is the current maximum in the differential amplifier 61-n. When compared with the value Vp (1) and Vn (1) exceeds the maximum value Vp (1), the output of the differential amplifier 61-n is inverted and the MOS switch 62-n is turned on. Then, the corresponding pixel output Vn (1) is output to the differential amplifier 64 via the voltage follower 63-n, and the pixel output Vn (1) becomes a new maximum value Vp (1). The new maximum value Vp (1) is differentially amplified by the dark pixel output Vd and the differential amplifier 64, and the maximum value VP (1) of the line 1 is obtained.

  At the timing when the φS (1) signal output from the control circuit 41 is input, SW (1) is turned on. Then, the maximum value VP (1) of the maximum value detection circuit Cl is input to the comparator 42, and the comparator 42 compares the maximum value VP (1) with the accumulation control level Vth. Then, when the differential output exceeds the set level Vth in the comparator 42, the control circuit 41 determines that the accumulation is completed, and outputs the accumulation end signal TG (1) to the corresponding line 1. This accumulation end signal TG (1) is output to all the pixels in the corresponding line 1 where the accumulation has been completed. The control circuit 41 and the comparator 42 perform the same processing in the maximum value detection circuits C2 to C4 by outputting φS (2) to φS (L) at each timing, for example, time division. The control circuit 41 and the comparator 42 constitute an accumulation control unit 40 that detects the output of the pixels on each line and controls the accumulation of the pixels on the line.

  According to this method, in the method in which accumulation control is performed using the maximum value VP (m) in one line, the end of accumulation can be determined by the pixel output itself to be monitored, while the circuit configuration is relatively simple. Accumulation control can be performed well.

  In the present embodiment, for example, as shown in FIG. 5, a horizontal pixel column consisting of 14 lines is divided into two in the vertical direction, and the horizontal pixel column group 28a, The accumulation control is performed based on the outputs of the HI maximum value detection circuits C1 to C7 and the HO maximum value detection circuits C1 to C7 corresponding to 128a, and the horizontal pixel column group is applied to the lower seven lines (8 to 14). Accumulation is controlled by the outputs of the HI maximum value detection circuits C8 to C14 and the HO maximum value detection circuits C8 to C14 corresponding to 28b and 128b. The HI maximum value detection circuits C1 to C7, the HO maximum value detection circuits C1 to C7, the HI maximum value detection circuits C8 to C14, and the HO maximum value detection circuits C8 to C14 constitute monitor units 30a, 30b, 130a, and 130b, respectively. A storage control unit such as the storage control unit 40 is provided for each of the monitor units 30a, 30b, 130a, and 130b.

  Similarly, for the 10 lines of the vertical pixel column, 10 lines are divided into two in the left-right direction, and the corresponding V maximum value detection circuits C6 to C6 in the vertical pixel column group 29a are applied to the right half 5 lines (6 to 10). Accumulation control is performed based on the output of C10, and accumulation control is performed on the left half 5 lines (1 to 5) by the output of the corresponding V maximum value detection circuits C1 to C5 in the vertical pixel column group 29b. . The V maximum value detection circuits C6 to C10 and the V maximum value detection circuits C1 to C5 constitute monitor units 30c and 30d, respectively, and an accumulation control unit such as the accumulation control unit 40 is provided for each of the monitor units 30c and 30d.

  In order to make it less susceptible to noise, the closer to each pixel column corresponding to the monitor units 30a to 30d, 130a, and 130b, the better. Further, with respect to the area sensor unit 27, since the horizontal pixel column and the vertical pixel column spread in a cross shape on the left and right and up and down, there is no pixel column in the four corner directions with respect to the center of the sensor chip 26. Therefore, in the present embodiment, as shown in FIG. 5, each of the monitor units 30 a to 30 d is arranged one by one in the four corner regions adjacent to both the vertical pixel column and the horizontal pixel column. With such an arrangement, the arrangement of the monitor units 30a to 30d on the sensor chip 26 can be easily made efficient, and the noise performance can be improved. The monitor units 130a and 130b are disposed adjacent to the horizontal pixel column groups 128a and 128b.

  Next, with reference to FIG. 7, the monitor range for accumulation control switched by the line 1 monitor range control unit 65-1 to the line L monitor range control unit 65-L will be described by taking the line 1 pixel column P1 as an example. .

  As shown in FIG. 7A, a predetermined range that is a partial region including the AF target position (focus target position) T1 is set in advance as a standard AF target area TA1. As shown in FIG. 7A, when the focal point is in the vicinity of the AF target position T1, it is sufficient for the line 1 monitor range control unit 65-1 to perform accumulation control only within the AF target area TA1. is there. Therefore, in such a case, the control unit 21 sets the same range as the AF target area TA1 as the accumulation control monitor pixel range Sa, and the line 1 monitor range control unit 65-1 uses the accumulation control monitor pixel. The selection switch 66-n for the pixels included in the range Sa is turned on. Accordingly, accumulation control can be performed using only the monitor pixel range Sa for accumulation control, that is, the AF target area TA1 as a monitor range.

  On the other hand, as shown in FIG. 7B, in a state in which the focus is greatly deviated from the AF target position T1, it is necessary to widen the calculation range for focus detection, so the monitor range for accumulation control is set wide. There is a need. Therefore, the control unit 21 sets a range obtained by adding a predetermined defocus amount to the AF target area TA1 as the accumulation control monitor pixel range Sb, and the line 1 monitor range control unit 65-1 performs the accumulation control. The pixel selection switch 66-n corresponding to the monitor pixel range Sb is turned on. Thus, a monitor range wider than the AF target area TA1 is set, and even when the focus is shifted from the AF target position T1, accumulation control can be performed appropriately. The predetermined defocus amount is determined based on the absolute value of the previous defocus amount detected by the most recent focus detection. Further, for example, when the absolute value of the defocus amount exceeds a value corresponding to a pixel region having a half width of the AF target area, a pixel region corresponding to a predetermined defocus amount in the AF target area TA1. Is set as the accumulation control monitor pixel range Sb.

  As described above, in the present embodiment, the on / off control of the switch 66-n by the line 1 monitor range control unit 65-1 to the line L monitor range control unit 65-L is performed in accordance with the in-focus state. It is possible to select a monitor range for accumulation control and perform optimum accumulation control according to the in-focus state.

  Further, in the present embodiment, by providing an external control circuit 41 in order to end accumulation based on the pixel output indicating the maximum value in all pixel columns, if the accumulation end is detected in any line, The control circuit 41 can be provided with a function of outputting accumulation end signals (TG (1) to TG (L)) to all lines. Accordingly, when selecting a main subject at the time of face detection, face recognition information for selecting a main subject based on the detection result of the AF sensor 20 by making the accumulation end timing of all the pixels the same. Makes it possible to get

  In the camera system according to the present embodiment, the focus detection process is performed after the first release (half-pressing operation), that is, the first release, and then the imaging process is performed after the next pressing operation, that is, the 2nd release. Done. The camera system according to the present embodiment sequentially captures a plurality of images by repeating these processes. First, focus detection and focus correction operations of the focus detection mechanism will be described. FIG. 8 is a flowchart showing an example of focus detection / focus correction operation executed under the control of the control unit 21.

  The control unit 21 determines whether there is a 1st release (step S201). The control unit 21 repeats the determination process of step S201 until it is determined that there is a 1st release (step S201; Yes), and each AF sensor 20 is connected to the AF sensor 20 via the AF controller 22 when it is determined that there is a 1st release. The accumulation operation for the line is started (step S202). When the storage end island is generated, the control unit 21 detects the storage time (current time) of the photoelectric conversion element array of the target island by the timer 55 (step S203). Here, the island is a plurality of lines having the set of distance measuring points P shown in FIG. The control unit 21 repeats this process until the accumulation is completed for all islands (step S204).

  Next, under the control of the control unit 21, the AF controller 22 starts pixel output transfer (CCD transfer) (step S205), performs predetermined illumination correction (step S206), and then follows the TTL phase difference method. A correlation calculation is performed (step S207), and a defocus amount is calculated as focus information (step S208). The AF controller 22 selects a distance measuring point P to be employed according to the calculated defocus amount. (Step S209) After that, the control unit 21 outputs the defocus amount of the distance measuring point P to the lens control unit 13, and the lens control unit 13 controls the motor driver 12 to focus the photographing lens 11. The lens is driven to the state (step S210). As a result, the single-lens reflex camera can take an image, and the process proceeds to an imaging operation.

  Furthermore, in the present embodiment, the monitor range for accumulation control can be freely set, so that when the AF target position is manually selected and when the AF target position is automatically selected as follows, It is also possible to perform sensor control by setting an optimum monitor range.

  In such a case, as shown in the flowchart of FIG. 9, the control unit 21 determines the selection content of the AF target position (step S1000). When it is determined that the AF target position is manually selected (step S1000: manual selection), the control unit 21 performs a first focus detection process (step S1001). If the control unit 21 determines that the AF target position is automatically selected without face detection (step S1000: automatic selection without face detection), it performs a second focus detection process (step S1002). If the control unit 21 determines that the AF target position is automatically selected with face detection (step S1000: automatic selection with face detection), the control unit 21 performs a third focus detection process (step S1003). Thereafter, the control unit 21 shifts to an imaging operation, and controls each component to perform an imaging process (step S1004).

  Next, the first focus detection process when manually selecting the AF target position will be described with reference to the flowchart of FIG. FIG. 10 is a flowchart showing a processing procedure of the first focus detection process shown in FIG. First, an AF target area is set by an operation of the user of the camera system (step S1100). When manually selecting the AF target position, it is necessary to keep a wide monitor range for accumulation control because the pixel range used for the calculation for focus detection is wide when the focus is greatly deviated. On the other hand, in a substantially in-focus state, appropriate processing can be performed even if accumulation control is performed with pixels only near the AF target position.

  Therefore, the control unit 21 acquires the distance measurement result of the latest focus detection, and determines whether or not the previous defocus amount detected by the latest focus detection is smaller than a predetermined value (step S1101). . For example, the control unit 21 determines whether or not the absolute value of the defocus amount is smaller than a value corresponding to a pixel region having a half width of the AF target area.

  When the control unit 21 determines that the previous defocus amount is smaller than the predetermined value (step S1101: Yes), the process can be appropriately performed even if the accumulation control is performed only on the pixels near the AF target position. The target area is set as a monitor range for accumulation control (step S1102). At this time, the line 1 monitor range control unit 65-1 to the line L monitor range control unit 65-L turns on the pixel selection switch 66-n corresponding to the AF target area. Thereby, the AF controller 22 can obtain the pixel output in the AF target area in the arithmetic processing for focus detection. Then, the AF sensor 20 and the AF controller 22 perform accumulation control processing in the AF target area set as the monitor range (step S1103), and calculate the defocus amount. As this accumulation control processing, processing operations shown in steps S202 to S209 of FIG. 8 are performed.

  On the other hand, when the control unit 21 determines that the previous defocus amount is large enough to deviate from the AF target area (step S1101: No), the control unit 21 sets an area wider than the AF target area as the monitor range. (Step S1104). At this time, the control unit 21 sets an area obtained by adding a pixel area conceived for the previous defocus amount to the AF target area as a monitor range. Then, the line 1 monitor range control unit 65-1 to the line L monitor range control unit 65-L turns on the pixel selection switch 66-n corresponding to the accumulation control monitor pixel range Sb. Then, the AF sensor 20 and the AF controller 22 perform accumulation control processing in an area wider than the AF target area set as the monitor range (step S1105), and calculate the defocus amount. As this accumulation control processing, processing operations shown in steps S202 to S209 of FIG. 8 are performed. Thereby, the AF controller 22 can obtain a pixel output in a wider range than the AF target area in the calculation process for focus detection.

  Then, the control unit 21 determines whether or not there is a 1st release (step S1106). When the control unit 21 determines that there is no first release (step S1106: No), the control unit 21 returns to step S1100. On the other hand, when the control unit 21 determines that the first release is present (step S1106: Yes), the lens drive amount is calculated from the defocus amount effect result immediately before the first release is pressed, and the photographing lens 11 is driven. The lens is driven (step S1107). As a result, the lens is driven to a position substantially close to the in-focus position, so that even if the accumulation control is performed only on the pixels near the AF target position, the process can be appropriately performed. Is set to the monitor range (step S1108).

  After the lens driving process, the AF sensor 20 and the AF controller 22 perform the accumulation control process in the AF target area set as the monitor range (step S1009), and calculate the defocus amount. As this accumulation control processing, processing operations shown in steps S202 to S209 of FIG. 8 are performed. Based on this result, the control unit 21 determines whether or not it is within the focusing range (step S1110).

  When the control unit 21 determines that it is not within the focusing range (step S1110: No), the process returns to step S1106. If the control unit 21 determines that it is within the focusing range (step S1110: Yes), it determines whether or not there is a 2nd release until there is a 2nd release (step S1111). When the control unit 21 determines that the 2nd release has occurred (step S1111: Yes), the first focus detection process ends.

  As described above, when manual selection of focus detection is set, the control unit 21 sets the monitor pixel range for accumulation control according to the previous defocus amount so that the focus detection process can be performed appropriately and accurately. ing.

  Next, the second focus detection process when the AF target is automatically selected without face detection will be described with reference to the flowchart of FIG. FIG. 11 is a flowchart illustrating a processing procedure of the second focus detection process illustrated in FIG. 9. When the AF target position is automatically selected without face detection, it is necessary to acquire defocus distribution information within a focus detectable range.

  For this reason, as shown in FIG. 11, the control unit 21 sets all the pixels of the AF sensor 20, that is, all the areas as the monitor range for accumulation control (step S1200). At this time, the line 1 monitor range control unit 65-1 to line L monitor range control unit 65-L turns on all the switches 66-1 to 66-N of the maximum value detection circuits C1 to C14. The AF sensor 20 and the AF controller 22 perform accumulation control processing in all areas in order to recognize the main subject (step S1201), and calculate the defocus amount. As this accumulation control processing, processing operations shown in steps S202 to S209 of FIG. 8 are performed. In this accumulation control process, accumulation control is performed for each line. At this time, when the maximum value among the outputs of the effective pixels in one line becomes equal to or higher than the predetermined value Vth, the control circuit 41 ends the accumulation of all the effective pixels in one line. Then, the AF controller 22 divides each line into a plurality of areas and calculates a defocus amount for each of the plurality of areas. By calculating in this way, sensor information in one line can be obtained without interruption, so the defocus amount can be calculated in a plurality of areas in one line. For example, as shown in FIG. Defocus amount distribution can be obtained. The XY plane corresponds to the two-dimensional arrangement plane of the memory sensor.

  Next, based on the defocus amount distribution information in the shooting screen as illustrated in FIG. 12, the control unit 21 focuses on the area indicating the center region emphasis and the closest defocus distribution. It is determined that the range is occupied by the main subject, and is detected as an automatic selection area (step S1202). For example, in the case shown in FIG. 12, the central area A1 having the largest defocus amount in the rear pin direction, that is, the closest distance is detected as the automatic selection area corresponding to the main subject.

  With this automatic selection area confirmed, the control unit 21 determines whether there is a 1st release (step S1203). If the control unit 21 determines that there is no first release (step S1203: No), the control unit 21 returns to step S1200 and performs processing for recognizing the main subject.

  If the control unit 21 determines that there is a first release (step S1203: Yes), after the lens is driven (step S1204), the determined automatic selection area is set as a monitor range (step S1205). At this time, the line 1 monitor range control unit 65-1 to the line L monitor range control unit 65-L sets the pixel selection switch 66-n corresponding to the detected automatic selection area under the control of the control unit 21. Turn on. The AF sensor 20 and the AF controller 22 perform accumulation control processing in this automatic selection area (step S1206), and calculate the defocus amount. As this accumulation control processing, processing operations shown in steps S202 to S209 of FIG. 8 are performed. Based on this result, the control unit 21 determines whether or not it is within the focusing range (step S1207).

  If the control unit 21 determines that it is not within the focusing range (step S1207: No), the process returns to step S1203. If the control unit 21 determines that it is within the focusing range (step S1207: Yes), it determines whether or not there is a 2nd release until there is a 2nd release (step S1208). If the control unit 21 determines that there is a 2nd release (step S1208: Yes), the second focus detection process is terminated.

  In this way, when automatic selection without focus detection face detection is set, the control unit 21 determines the defocus amount distribution in the shooting screen based on the output results of all pixels of all lines of the AF sensor 20. Is used to detect the range occupied by the main subject, and the range occupied by the detected main subject is set as the monitor pixel range for accumulation control.

  Next, with reference to the flowchart of FIG. 13, a description will be given of the third focus detection process when the AF target is automatically selected with face detection. FIG. 13 is a flowchart showing a processing procedure of the third focus detection processing shown in FIG. In FIG. 13, it is assumed that face detection is performed based on sensor information from the AF sensor 20, and subject distance distribution information is acquired within a range that can be monitored by the AF sensor 20.

  For this reason, as shown in FIG. 13, the control unit 21 sets all pixels of the AF sensor 20, that is, all areas, as a monitor range for accumulation control (step S1300). At this time, the line 1 monitor range control unit 65-1 to line L monitor range control unit 65-L turns on all the switches 66-1 to 66-N of the maximum value detection circuits C1 to C14. The AF sensor 20 and the AF controller 22 perform accumulation control processing in all areas for face detection (step S1301), and calculate the defocus amount. As the accumulation control process, the processing operation shown in steps S202 to S205 in FIG. 8 is performed. The AF sensor 20 performs an accumulation process common to all the lines of the AF sensor 20, and when the control circuit 41 detects the accumulation end in any line, the accumulation end signal for all the lines 1 to L is detected. (TG (1) to TG (L)) are output and the accumulation of all the pixels is simultaneously terminated. Thus, by making the accumulation end timings of all the pixels the same, the AF sensor 20 can be used as an area sensor.

  Then, the control unit 21 detects a face area based on the pixel output data of all lines of the AF sensor 20 (step S1302). For example, the control unit 21 obtains the pixel output level distribution based on the pixel output data of all the lines of the AF sensor 20, and among these, an area where the same level is located, that is, an area determined to be the same subject. Extract. Then, when the shape of the extracted region is substantially circular, the control unit 21 determines that this region corresponds to the face of the subject, and detects this region as a face area.

  Next, the control unit 21 sets the detected face area as a monitor range for accumulation control (step S1303). The AF sensor 20 and the AF controller 22 perform accumulation control processing in the face area set as the monitor range (step S1304), and calculate the defocus amount. As this accumulation control processing, processing operations shown in steps S202 to S209 of FIG. 8 are performed.

  Subsequently, the control unit 21 determines whether or not there is a first release (step S1305). If the control unit 21 determines that there is no first release (step S1305: NO), the process returns to step S1300, and the AF sensor 20 and the AF controller 22 perform accumulation processing on all lines.

  If the control unit 21 determines that there is a first release (step S1305: Yes), after driving the lens (step S1306), the AF target area is set to the monitor range (step S1307). A predetermined range that is a partial area including the AF target position is set in advance as a standard AF target area. The AF sensor 20 and the AF controller 22 perform accumulation control in the AF target area set as the monitor range (step S1308), and calculate the defocus amount. As this accumulation control processing, processing operations shown in steps S202 to S209 of FIG. 8 are performed. Based on this result, the control unit 21 determines whether or not it is within the focusing range (step S1309).

  When the control unit 21 determines that it is not within the focusing range (step S1309: No), the process returns to step S1305. If the control unit 21 determines that it is within the focusing range (step S1309: Yes), it determines whether or not there is a 2nd release until there is a 2nd release (step S1310). When the control unit 21 determines that the 2nd release has occurred (step S1310: Yes), the third focus detection process ends.

  As described above, when automatic selection with face detection for focus detection is set, the control unit 21 obtains the output distribution of all pixels of all lines of the AF sensor 20, and based on this, the range occupied by the main subject is determined. The range occupied by the detected main subject is set as a monitor pixel range for accumulation control.

  When face detection is performed by another sensor such as an image sensor for photographing instead of the AF sensor 20, a monitor range for accumulation control may be set in accordance with the face detection result. The accumulation control by the AF sensor 20 and the AF controller 22 may be performed within the range. That is, in this case, as the third focus detection process, the face area detected by another sensor is set as a monitor range, and after performing the accumulation process in this range, the processes in steps S1305 to S1310 are performed. .

  As described above, in the present embodiment, the focus detection process is performed by setting the optimum monitor range according to the AF target position selection condition, so that the focus detection process can be performed efficiently and accurately.

DESCRIPTION OF SYMBOLS 10 Interchangeable lens 11 Shooting lens 12 Motor driver 13 Lens control part 14 Main mirror 15 Viewfinder screen 16 Viewfinder optical system 17 Viewfinder eyepiece 18 Submirror 19 AF optical system 20 AF sensor 21 Control part 22 AF controller 23 Focal plane shutter 24 Image sensor 26 sensor chip 27 area sensor unit 28a, 28b, 128a, 128b horizontal pixel column group 29a, 29b vertical pixel column group 30a-30d monitor unit 32 condenser lens 34 separator lens 35A, 35B sensor array 40 accumulation control unit 41 control circuit 42 comparator 51 Sequencer 52 A / D Converter 53 Memory 54 AF Operation Unit 55 Timer 56 Register 57 Flash ROM
61-1 to 61-n Differential amplifier 62-1 to 62-n MOS switch 63-1 to 63-n Voltage follower 64 Differential amplifier 65-1 to 65-L Monitor range controller 66-1 to 66-n Selection switch C1-C14 Maximum value detection circuit

Claims (7)

An area sensor having a plurality of pixel columns each composed of a plurality of pixels, detecting output of the pixels for each pixel column to perform accumulation control of the pixels included in the pixel column, and based on the detected output of the pixels In a focus detection device that performs focus detection,
Detection range setting means for setting a detection range of pixel output in each of the plurality of pixel columns of the area sensor;
Detection range control means for selecting an output of a pixel corresponding to the detection range set by the detection range setting means as an effective signal;
Accumulation control means for controlling the accumulation of pixels in the pixel column by detecting the output of the pixels selected by the detection range control means as an effective signal;
A focus detection apparatus comprising:   2. The focus detection apparatus according to claim 1, further comprising a switch for electrically connecting or disconnecting the pixel and the accumulation control unit for each pixel under the control of the detection range control unit. The focus detection device can set manual selection or automatic selection of the focus target position,
3. The focus detection according to claim 1, wherein the detection range setting unit sets a detection range according to a previous defocus amount detected by the most recent focus detection when the manual selection is set. apparatus.   When the absolute value of the previous defocus amount is smaller than a predetermined value, the detection range setting means sets a predetermined standard detection region that is a partial region including a focus target position in the pixel row as the detection range. The focus detection apparatus according to claim 3, wherein when the absolute value of the previous defocus amount is larger than a predetermined value, a range wider than the standard detection region is set as the detection range.   When the absolute value of the previous defocus amount is larger than a predetermined value, the detection range setting means sets, as the detection range, an area obtained by adding a pixel area corresponding to the previous defocus amount to the standard detection area. The focus detection apparatus according to claim 4, wherein the focus detection apparatus is characterized. The focus detection device can set manual selection or automatic selection of the focus target position,
When the automatic selection is set, the detection range setting means detects a range occupied by a main subject as a focus target based on an output result of all pixels of the area sensor, and a range occupied by the detected main subject The focus detection device according to claim 1, wherein the detection range is set as the detection range.   2. The accumulation control unit terminates accumulation of pixels in the pixel column when a maximum value exceeds a predetermined value among outputs during accumulation of pixels selected by the detection range control unit. The focus detection apparatus as described in any one of -6.

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