JP5482447B2 - Ranging point determination system, autofocus system, and camera - Google Patents

Description

  The present invention relates to a distance measuring point determination system that determines a used distance measuring point used for focusing from among a plurality of fixed distance measuring points in order to quickly focus on a subject.

  A phase difference AF function and a contrast AF function are known as autofocus (AF) functions for automatically focusing a subject on an imaging surface.

  In a conventional digital single-lens reflex camera, a phase difference AF function that completes the focusing operation in a short time is generally executed. In the execution of the phase difference AF function, the focus lens is displaced so that an optical image located at a predetermined distance measuring point within the imaging range is focused on the imaging surface (see Patent Document 1).

  Recent digital single-lens reflex cameras have a live view function for displaying an optical image of a subject on a monitor in a shooting standby state. In order to execute the live view function, the optical image of the subject is received by the image sensor.

  The image signal generated by the image sensor can be used not only for display on the monitor but also for image analysis. For example, by analyzing a received image, it is possible to automatically detect a specific type of photographing target such as a human face. It has also been proposed to perform exposure adjustment and focus adjustment on the detected subject.

  In general, the detected position of the object to be photographed does not coincide with the distance measuring point at the predetermined position as described above. Therefore, in the case of automatically detecting an imaging target, a contrast AF function capable of focusing on a subject at any position in the imaging range is executed instead of the phase difference AF function.

  However, when the contrast AF function is executed, it takes a long time to complete the focusing operation in order to determine whether or not the focusing lens is in focus.

  Therefore, although it is desired to execute the phase difference AF function even in the case of automatically detecting an imaging target, it is unclear which distance measurement point is optimal.

JP 2001-281530 A

  Therefore, an object of the present invention is to provide a distance measuring point determination system that determines an optimum distance measuring point in order to cause a camera that can automatically detect an imaging target to execute a phase difference AF function.

  The distance measuring point determination system according to the present invention is a measurement method used for focusing a main subject, which is a subject to be focused by phase difference AF, based on a plurality of fixed distance measuring points whose positions in a photographing range are predetermined. A distance measuring point determination system for determining a distance point, wherein a plurality of lines in which a part of a subject image within a photographing range is received for phase difference detection and a specific position in a longitudinal direction is determined as a fixed distance measuring point A sensor, an image sensor that receives an optical image of the shooting range and generates an image signal corresponding to the received optical image, an image detection unit that detects a main subject based on the image signal, and a main detected by the image detection unit A position detection unit that detects a subject position that is a position within the photographing range of the subject, and a distance calculation that calculates a first distance that is a distance between the subject position and the fixed distance measuring point for each of the plurality of fixed distance measuring points. And a determination unit for determining whether or not there are a plurality of first distances that are substantially equal and minimum among a plurality of first distances calculated for each of the plurality of fixed ranging points; A plurality of fixed distance measuring points corresponding to a plurality of first distances that are minimum when the determination unit determines that there are a plurality of first distances that are substantially equal and minimum among the plurality of first distances. When there are two primary ranging points determined by the same line sensor among a plurality of primary ranging points selected by the first selection unit and a first selection unit that selects the first ranging point In this case, a point between two primary ranging points on the same line sensor is set as a secondary ranging point, and the same line sensor is selected among the plurality of primary ranging points selected by the first selection unit. If there is only one primary ranging point, one primary ranging point on the same line sensor is used as the secondary ranging point. A setting unit for setting, a contrast calculating unit for calculating a subject position and a contrast value at the plurality of secondary ranging points based on an image signal when a plurality of secondary ranging points are set by the setting unit, and a subject And a second selection unit that selects a secondary distance measuring point having a contrast value closest to the contrast value at the position and determines it as a used distance measuring point.

  Further, the setting unit performs secondary ranging for the points between all primary ranging points when all of the plurality of primary ranging points selected by the first selection unit are set on the same line sensor. Preferably, the second selection unit determines the secondary ranging point as the use ranging point when a single secondary ranging point is set by the setting unit.

  Furthermore, it is preferable that the setting unit sets a plurality of primary ranging points selected by the first selection unit as a plurality of secondary ranging points.

  Further, the second selection unit is configured such that when the determination unit determines that there is a single first distance that is substantially equal and minimum among the plurality of first distances, It is preferable to fix the fixed distance measuring point corresponding to the first distance as the use distance measuring point.

  Further, the discriminating unit is a product of the first distance and the first coefficient in which the difference between the two first distances calculated for the two fixed distance measuring points is shorter than the two first distances. Preferably, it is determined that the two first distances are substantially equal to each other if the distance is less than

  Further, the determining unit determines that the two first distances are substantially equal to each other when a difference between the two first distances calculated for the two fixed distance measuring points is less than a threshold value. It is preferable to do.

  The autofocus system of the present invention receives a part of a subject image within a shooting range for phase difference detection, and includes a plurality of line sensors in which a specific position in the longitudinal direction is defined as a fixed distance measuring point, An image sensor that receives an optical image and generates an image signal corresponding to the received optical image, an image detector that detects a main subject that is a subject to be focused based on the image signal, and a main detected by the image detector A first position detection unit that detects a subject position that is a position within the photographing range of the subject, and a first distance that is a distance between the subject position and the fixed distance measuring point is calculated for each of the plurality of fixed distance measuring points. And determining whether there are a plurality of first distances that are substantially equal and minimum among the plurality of first distances calculated for each of the plurality of fixed distance measuring points. Department and size A plurality of fixed distance measuring points corresponding to a plurality of first distances that are minimum when the unit determines that there are a plurality of first distances that are substantially equal and minimum among the plurality of first distances; When there are two primary ranging points determined by the same line sensor among a first selection unit selected as a primary ranging point and a plurality of primary ranging points selected by the first selection unit Sets a point between two primary ranging points on the same line sensor as a secondary ranging point, and determines the same line sensor among a plurality of primary ranging points selected by the first selection unit. If there is one primary ranging point, a setting unit that sets one primary ranging point on the same line sensor as a secondary ranging point, and a plurality of secondary ranging points are set by the setting unit. When set, a contrast value is calculated for calculating the contrast value at the subject position and multiple secondary ranging points based on the image signal. A trust calculation unit; a second selection unit that selects a secondary ranging point that has a contrast value closest to the contrast value at the subject position, and determines the used ranging point; and a used measurement unit determined by the second selection unit. A second position detection unit that detects the position of the focus lens that makes the subject in focus by causing the line sensor to receive the subject located at the distance point, and the second position detection unit. And a drive unit that displaces the focus lens at a position.

  The camera of the present invention receives a part of a subject image within a photographing range for phase difference detection, and includes a plurality of line sensors in which a specific position in the longitudinal direction is defined as a fixed distance measuring point, and an optical image of the photographing range. An image sensor that generates an image signal corresponding to the received optical image, an image detection unit that detects a main subject that is a subject to be focused based on the image signal, and a main subject detected by the image detection unit A first position detection unit that detects a subject position that is a position within the shooting range, and a distance that calculates a first distance that is a distance between the subject position and the fixed distance measuring point for each of the plurality of fixed distance measuring points. A calculating unit and a determining unit for determining whether or not there are a plurality of first distances that are substantially equal and minimum among the plurality of first distances calculated for each of the plurality of fixed ranging points; The discriminator has a plurality of first When it is determined that there are a plurality of first distances that are substantially equal and minimum among the distances, a plurality of fixed distance measuring points corresponding to the plurality of first distances that are the smallest are selected as primary distance measuring points. When there are two primary ranging points determined by the same line sensor among a plurality of primary ranging points selected by the first selection unit and the first selection unit, the same selection is made on the same line sensor. A point between two primary ranging points is set as a secondary ranging point, and a primary ranging point determined by the same line sensor among a plurality of primary ranging points selected by the first selection unit is When there is one, a setting unit that sets one primary ranging point on the same line sensor as a secondary ranging point, and an image when a plurality of secondary ranging points are determined by the determining unit A contrast calculation unit for calculating a contrast value at a subject position and a plurality of secondary ranging points based on the signal; A second selection unit that selects a secondary ranging point that has a contrast value closest to the contrast value at the subject position and determines it as a used ranging point, and a used ranging point that is confirmed by the second selection unit. The focus lens is positioned at a position detected by the second position detector, a second position detector that detects the position of the focus lens that makes the subject in focus by causing the line sensor to receive the subject, and a phase difference method. And a drive unit for displacing the head.

  According to the present invention, it is possible to determine the optimum distance measuring point for executing the phase difference AF function for the main subject that is automatically detected.

1 is a block diagram schematically showing an internal configuration of a digital single-lens reflex camera having a distance measuring point selection system to which a first embodiment of the present invention is applied. FIG. FIG. 10 is a layout diagram showing first to ninth fixed distance measuring points defined within an imaging range. It is a notional block diagram of an AF sensor module. It is a front view of a line sensor unit. It is an image displayed on the LCD when a face is detected. FIG. 10 is an arrangement diagram of secondary ranging points set in the first to ninth fixed ranging points set when there are a plurality of primary ranging points having corresponding fixed corresponding points on the same line sensor. It is a figure which shows the state where the position of the detected face is close to a single fixed distance measuring point. It is a figure which shows the state where the fixed distance measuring point near the position of the detected face is only two points of the same line. It is a figure which shows the state where the fixed distance measuring points near the position of the detected face are only two points of a different line. It is a figure which shows the state in which the fixed ranging point near the position of the detected face is only two points of the same line, and one point of another line. It is a figure which shows the state in which the fixed distance measuring points near the position of the detected face are only two points of the same line, and two points of another line. It is a 1st flowchart for demonstrating control of the operation | movement of each site | part performed by CPU in imaging | photography mode. It is a 2nd flowchart for demonstrating control of the operation | movement of each site | part performed by CPU in imaging | photography mode. It is a flowchart which shows the subroutine of the ranging point determination process performed by CPU. It is a flowchart of the imaging process performed by CPU.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram schematically showing an internal configuration of a digital single-lens reflex camera having a distance measuring point determination system to which the first embodiment of the present invention is applied.

  The digital single-lens reflex camera 10 includes a photographing optical system 11, a main mirror 12, a shutter 13, an image sensor 14, an AFE 15, a digital signal processor (DSP) 16 (an image detection unit, a position detection unit, a contrast calculation unit), and a CPU 17 (a distance calculation). Unit, a determination unit, a first selection unit, a setting unit, a second selection unit), a lens driving mechanism 18, and the like.

  The photographing optical system 11 is formed by a plurality of lenses including a focus lens 11f and a variable power lens (not shown). The focus lens 11 f and the variable power lens are displaced along the optical axis of the photographing optical system 11 by being driven by the lens driving mechanism 18.

  An image sensor 14 is disposed on the optical axis so as to be perpendicular to the optical axis of the photographing optical system 11. An optical image of the subject is formed on the light receiving surface of the image sensor 14 by the photographing optical system 11. A main mirror 12 and a shutter 13 are disposed between the photographing optical system 11 and the image sensor 14.

  The transmission destination of the optical image transmitted through the photographing optical system 11 is switched by the main mirror 12. When the main mirror 12 is closed, the optical image is reflected toward the pentaprism 19 and transmitted to a viewfinder (not shown). When the main mirror 12 is opened upward, the optical image reaches the shutter 13. The main mirror 12 is opened and closed by a mirror drive mechanism (not shown).

  The shutter 13 switches between shielding and reaching the optical image sensor 14. When the shutter 13 is closed, the optical image does not reach the image sensor 14. On the other hand, when the shutter 13 is opened, the optical image reaches the image sensor 14.

  When the shutter 13 is opened and the optical image reaches the image sensor 14, an image signal corresponding to the optical image is generated. The generated image signal is subjected to CDS processing and AGC processing in the AFE 15. In addition, A / D conversion processing is performed and converted into image data. The image data is transmitted to the DSP 16.

  In the DSP 16, predetermined data processing is performed on the image data. Image data that has undergone predetermined data processing is stored in the image memory 20. Alternatively, the image data is transmitted to the LCD 21 and an image corresponding to the image data is displayed on the LCD 21.

  The DSP 16 is connected to the CPU 17. Based on the data received from the CPU 17, the DSP 16 controls processing such as data processing for image data, storage of image data, and display of an image corresponding to the image data.

  The CPU 17 controls the operation of each part of the digital single lens reflex camera 10 like the lens driving mechanism 18 and the AF sensor module 22. The CPU 17 is connected to the ROM 23. The ROM 23 stores data necessary for the control of each part by the CPU 17.

  The digital single lens reflex camera 10 can execute a phase difference AF function or a contrast AF function. As will be described below, the phase difference AF function is executed with the main mirror 12 closed. The contrast AF function is executed with the main mirror 12 and the shutter 13 open.

  A sub mirror 24 is provided between the main mirror 12 and the shutter 13. The main mirror 12 is a half mirror, and a part of the optical image transmitted through the photographing optical system 11 is reflected by the main mirror 12 and reaches the pentaprism 19 as described above. A part of the optical image transmitted through the photographing optical system 11 passes through the main mirror 12 and is reflected toward the AF sensor module 22 by the sub mirror 24.

  The AF sensor module 22 detects a defocus amount, that is, a shift between the current position of the focus lens 11f and the in-focus position for focusing the subject. Note that the defocus amount of the subject at the distance measuring point within the photographing range can be detected.

  As shown in FIG. 2, first to ninth fixed distance measuring points FP1 to FP9 corresponding to predetermined positions in the photographing range CA are determined. The position of the fixed distance measuring point is stored in the ROM 23 as data. The positions of the first to ninth fixed distance measuring points FP1 to FP9 are determined so as to form a 3 × 3 matrix.

  Fixed ranging points arranged from the left side to the right side in the first row from the upper side are defined as first to third fixed ranging points FP1 to FP3. Fixed ranging points arranged from the left side to the right side of the second row are determined as fourth to sixth fixed ranging points FP4 to FP6. In addition, fixed ranging points arranged from the left side to the right side in the third row are defined as seventh to ninth fixed ranging points FP7 to FP9.

When the phase difference AF function is executed, a new distance measurement set based on any of the first to ninth fixed distance measurement points FP1 to FP9 or the first to ninth fixed distance measurement points FP1 to FP9. The point is determined as a distance measuring point to be used for executing the phase difference AF. The selection of any one of the first to ninth fixed distance measuring points FP1 to FP9 and the setting of a new distance measuring point will be described later in detail.

  The configuration of the AF sensor module 22 will be described in detail. As shown in FIG. 3, the AF sensor module 22 includes a condenser lens 22c, a diaphragm mask 22m, a separator lens 22s, and a line sensor unit 22u.

  The optical image reflected by the sub mirror 24 is condensed by the condenser lens 22c and emitted to the aperture mask 22m. Two apertures 22o are formed in the aperture mask 22m. Optical images that pass through the left end and the right end of the exit pupil of the photographing optical system 11 pass through the respective openings 22o and are collected by separate separator lenses 22s. The optical image condensed by the separator lens 22s enters the line sensor unit 22u.

  As shown in FIG. 4, the line sensor unit 22u is provided with first to third CCD line sensors 22u1 to 22u3 which are parallel to each other. The first to third line sensors 22u1 to 22u3 can detect the amount of light received at each position in the longitudinal direction.

  A reference area sa and a reference area ra are defined for the first to third line sensors 22u1 to 22u3. The reference region sa and the reference region ra are determined so as to be the left and right objects with respect to the center in the longitudinal direction of the first to third line sensors 22u1 to 22u3.

  The optical image condensed by the right separator lens 22s, that is, the optical image passing through the left end of the exit pupil enters the reference area sa, and the optical image condensed by the left separator lens 22s, that is, the right end of the exit pupil The passed optical image enters the reference region ra.

  The first line sensor 22u1 is disposed at a position where a linear optical image passing through the first to third fixed distance measuring points FP1 to FP3 in the photographing range CA is incident. The second line sensor 22u2 is disposed at a position where a linear optical image passing through the fourth to sixth fixed distance measuring points FP4 to FP6 in the photographing range CA is incident. The third line sensor 22u3 is disposed at a position where a linear optical image passing through the seventh to ninth fixed distance measuring points FP7 to FP9 is incident in the photographing range CA.

  First to third fixed corresponding points CP1 to CP3 are determined in the standard area sa and the reference area ra on the first line sensor 22u1. The first fixed corresponding point CP1 is a first line through which the optical image of the first fixed distance measuring point FP1 reaches when the subject at the first fixed distance measuring point FP1 is imaged on the image sensor 14. It is determined at a point on the sensor 22u1. The second and third fixed corresponding points CP2 and CP3 are similarly determined.

  Fourth to sixth fixed corresponding points CP4 to CP6 are defined in the standard area sa and the reference area ra on the second line sensor 22u2. The fourth to sixth fixed corresponding points CP4 to CP6 are determined in the same manner as the first fixed corresponding point CP1.

  Seventh to ninth fixed corresponding points CP7 to CP9 are defined in the standard area sa and the reference area ra on the third line sensor 22u3. The seventh to ninth fixed corresponding points CP7 to CP9 are determined in the same manner as the first fixed corresponding point CP1.

  As will be described later, when any one of the first to ninth fixed distance measuring points FP1 to FP9 is determined as the used distance measuring point, the fixed corresponding point determined as the used distance measuring point is the reference area sa and the reference area. selected in ra. When a fixed corresponding point is selected, it is a position that receives a light amount that can be regarded as equal in both the reference area sa and the reference area ra in the vicinity of the selected fixed corresponding point, and the distance from the fixed corresponding point is equal in the opposite direction The position is detected. A defocus amount is detected according to the detected distance.

  Although the first to ninth fixed distance measuring points FP1 to FP9 are determined in advance, points within the photographing range CA corresponding to arbitrary points on the first to third line sensors 22u1 to 22u3 are measured. It can be set as a distance point. When a distance measuring point is newly set, the defocus amount of the subject located at the used distance measuring point is detected using the distance measuring point set in the same manner as described above as the used distance measuring point.

  The AF sensor sensor module 22 is connected to the CPU 17. The AF sensor module 22 is controlled by the CPU 17 and detects the defocus amount at the used distance measuring point. The distance measuring point may be specified by a user input to an input button (not shown), or may be automatically determined by the CPU 17 as will be described later.

  The detected defocus amount is transmitted to the CPU 17. The CPU 17 controls the lens driving mechanism 18 based on the defocus amount, and displaces the focus lens 11f to a position where the subject at the distance measuring point to be used is focused. In this way, the phase difference AF function performs the focusing operation by displacing the focus lens 11f based on the detected defocus amount.

  On the other hand, when executing the contrast AF function, the main mirror 12 and the shutter 13 are opened as described above, and the optical image of the subject is guided to the image sensor 14. The image sensor 14 continuously generates image signals.

  As described above, the generated image signal is transmitted to the DSP 16 via the AFE 15. The DSP 16 calculates a contrast value at a specific position in the shooting range CA. The specific position may be specified by a user input to the input button or may be automatically specified by the DSP 16.

  When the generation of the image signal of one frame is finished, the focus lens 11f is displaced based on the control of the CPU 17. After the displacement, an image signal of one frame is generated again. While the focus lens 11f is gradually displaced, the contrast value in the image signal generated at each displacement position is calculated.

  When the calculated contrast value is maximum, it is determined that the subject is in focus. The contrast AF function is executed by displacing the focus lens 11f to a position where the contrast value is maximized.

  Note that both the phase difference AF function and the contrast AF function are executed when the operation mode of the digital single-lens reflex camera 10 is the photographing mode. The digital single-lens reflex camera 10 has a first shooting mode in which an optical image of a subject can be observed with a viewfinder in a shooting standby state, and a second shooting mode in which an optical image of the subject can be observed with an LCD 21 in a shooting standby state. . Note that the first and second shooting modes are selected by input by the user to the input button.

  In the first shooting mode, the main mirror 12 is closed in the shooting standby state. As described above, the optical image of the subject is guided to the viewfinder. Therefore, the user can observe the subject using the viewfinder.

  When the CPU 17 detects the ON state of the distance measuring switch (not shown) by pressing the release button (not shown) halfway in the shooting standby state, the above-described phase difference AF function is executed. When the ON state of a photometry switch (not shown) is detected by half-pressing the release button, the subject is photometrically determined and exposure conditions such as aperture, shutter speed, and / or sensitivity (gain) are determined.

  Further, when the CPU 17 detects that the photographing switch (not shown) is turned on by fully pressing the release button in the photographing standby state, the photographing operation is executed. In the imaging operation, the main mirror 12 is opened upward, and the shutter 13 is opened only during a predetermined shutter speed. While the main mirror 12 and the shutter 13 are open, an optical image is received by the image sensor 14.

  An image signal corresponding to the optical image received by the image sensor 14 is generated. The generated image signal is transmitted to the DSP 16 via the AFE 15 as described above. The DSP 16 performs image processing for a still image and stores it in the image memory 20.

  In the second shooting mode, the main mirror 12 is opened upward in the shooting standby state. The shutter 13 is also opened, and the optical image of the subject is guided to the image sensor 14. In the image sensor 14, an image signal of one frame is generated at a predetermined time interval, for example, every 1/60 seconds.

  The generated image signal is transmitted to the DSP 16 via the AFE 15 as described above. In the DSP 16, image processing for moving images is performed and transmitted to the LCD 21. An image corresponding to the received image data is displayed on the LCD 21. The image displayed on the LCD 21 is switched at the same interval as the image signal generation interval, that is, every 1/60 seconds. A real-time moving image is displayed on the LCD 21 by switching the display image.

  When the CPU 17 detects that the distance measuring switch (not shown) is turned on by half-pressing a release button (not shown) in the shooting standby state, either the contrast AF function or the phase difference AF function is executed. . Note that the AF function to be executed in the second shooting mode is set to any one by an input to the input button by the user.

  When the contrast AF function is selected, the above-described operation is performed while the main mirror 12 is opened, thereby completing the contrast AF function.

  On the other hand, when the phase difference AF function is selected, the main mirror 12 is temporarily closed after detecting the ON state of the distance measuring switch, and the optical image of the subject is guided to the AF sensor module 22. As described above, the AF sensor module 22 detects the defocus amount, and the focus lens 11f is displaced based on the detected defocus amount. When the defocus amount is detected by the AF sensor module 22, the main mirror 12 is again opened upward.

  When the ON state of the photometry switch is detected by pressing the release button halfway in the shooting standby state, the subject is metered in the same manner as in the first shooting mode, and exposure conditions such as aperture, shutter speed, and / or sensitivity are determined. .

  When the imaging switch is turned on by the CPU 17 when the release button is fully pressed in the shooting standby state, the imaging operation is executed. Unlike the first shooting mode, since the shutter 13 is opened in the shooting standby state, the shutter 13 is once closed and then opened only for a predetermined shutter speed, while the shutter 13 is opened. The optical image is received by the element 14.

  An image signal corresponding to the received optical image is generated by the image sensor 14. As in the first shooting mode, the image signal is subjected to still image processing in the DSP 16 and then stored in the image memory 20.

  The digital single-lens reflex camera 10 is provided with a face detection function. The face detection function can be executed when the operation mode of the digital single-lens reflex camera 10 is the second shooting mode. ON / OFF of the face detection function execution is switched by an operation input to the input button by the user.

  When the face detection function is turned on, a face in the captured image can be detected. When a face is detected, exposure adjustment and AF are performed on the detected face. If the distance measurement switch and the photometry switch are turned on with the face detection function turned on, face detection is started.

  As described above, in the second shooting mode, an image signal is generated during shooting standby. In the DSP 16, image analysis such as feature extraction and color discrimination is performed on the received image data, and a face within the imaging range CA of the image corresponding to the image data is detected.

  When the DSP 16 detects a face, the image data is superimposed so that a frame surrounding the detected face is superimposed on the image. Based on the image data subjected to superimposition, the LCD 21 displays a frame line 25 around all detected faces as shown in FIG.

  When a face is detected from the image, exposure adjustment and AF are executed with the detected face as the main subject. When a plurality of faces are detected, a single face is determined as a main subject to be subjected to exposure adjustment or AF based on a predetermined reference, and exposure adjustment or AF is executed. For example, it is determined based on the position in the photographing range CA, the size of the face, and the like.

  A single face is determined as the main subject based on the registered face. That is, when a registered face is included among the detected faces, the same face as the registered face is determined as the main subject.

  The face registration is selected from image data stored in the image memory 20 or a face included in an image corresponding to image data received from an external computer or the like connected via a connector (not shown). It is executed by doing.

  When a single face is determined as the main subject, the DSP 16 detects the brightness of the face determined as the main subject. Based on the detected luminance, the exposure condition is determined as described above.

  When a single face is defined as the main subject, either the contrast AF function or the phase difference AF function is executed as described above.

  When the contrast AF function is selected, the contrast value at the position where the optical image of the face determined as the main subject is received is calculated. As described above, the focus lens 11f is displaced so that the contrast value at the position where the optical image of the face is received is maximized.

  When the phase difference AF function is selected, the position for receiving the optical image of the face determined as the main subject is transmitted to the CPU 17 as data. Note that the center of the frame line and the position between both eyes are determined as the light receiving position of the optical image of the face.

  As described above, in the phase difference AF function, a focusing operation is performed on a subject on which an optical image is focused on a single used distance measuring point within the photographing range CA. In order to determine the used distance measuring points, the CPU 17 calculates distances (first distances) between the received light receiving positions and the first to ninth fixed distance measuring points FP1 to FP9.

  The minimum value Lmin in the calculated distance is detected. It is determined whether or not there is another fixed distance measuring point that is a distance that can be regarded as substantially equal to the detected minimum value Lmin.

  The distance that can be regarded as substantially equal to the detected minimum value Lmin is a distance determined as follows. First, the detected minimum value Lmin is multiplied by the first coefficient a1. The distance from which the difference from the minimum value Lmin is less than the minimum value (a1 × Lmin) multiplied by the first coefficient is determined as a distance that can be regarded as substantially equal to the minimum value Lmin. That is, the distance L satisfying the following expression (1) is considered to be substantially equal to the minimum value Lmin.

  (L−Lmin) <a1 × Lmin (1)

  Note that the first coefficient a1 is set to 0.05 in the present embodiment. Further, it is a value that is at least larger than 0, and may be set to an appropriate value in order to achieve the above-described object.

  When there is no other fixed distance measuring point that is a distance that can be regarded as substantially equal to the minimum value Lmin, the fixed distance measuring point whose distance from the light receiving position is the minimum value Lmin is selected. When a single fixed distance measuring point is selected, the selected fixed distance measuring point is determined as a used distance measuring point. When the used distance measuring point is determined, as described above, the AF sensor module 22 detects the defocus amount at the used distance measuring point and the displacement of the focus lens 11f based on the defocus amount.

  On the other hand, when there is another fixed distance measuring point that is a distance that can be considered to be substantially equal to the minimum value Lmin, the distance from the light receiving position and the fixed distance measuring point at which the distance from the light receiving position is the minimum value Lmin is ( All the fixed distance measuring points having the distance L satisfying the expression 1) are selected as the primary distance measuring points.

  When a plurality of primary ranging points are selected, secondary ranging points according to the first rule are newly set based on the primary ranging points. In the first rule, the secondary ranging point is set by the following two methods.

  When there are a plurality of primary ranging points having corresponding fixed corresponding points on the same line sensor, the centers of the plurality of primary ranging points are newly set as secondary ranging points. For example, as shown in FIG. 6, when the fourth and fifth fixed ranging points FP4 and FP5 are selected as the primary ranging points among the fixed ranging points corresponding to the second line sensor 22u2. The midpoint MP of the fourth and fifth fixed ranging points FP4 and FP5 is determined as the secondary ranging point.

  On the other hand, when there is a single primary ranging point with corresponding fixed corresponding points on the same line sensor, a single primary ranging point is set as the secondary ranging point. For example, when the second fixed ranging point FP2 is selected as the primary ranging point among the fixed ranging points corresponding to the first line sensor 22u2, the second fixed ranging point FP2 is two. The next distance measuring point is set (see FIG. 2).

  When there are a plurality of newly set secondary ranging points, as will be described below, one of the secondary ranging points is selected and determined as a used ranging point. When a plurality of secondary ranging points are set, the CPU 17 controls the DSP 16 to calculate the contrast value at the secondary ranging point and the contrast value at the light receiving position of the optical image of the main subject based on the image signal. . After the contrast value is calculated, a single secondary distance measuring point having a contrast value closest to the contrast value at the light receiving position in the optical image of the main subject is selected and determined as the distance measuring point to be used.

  On the other hand, when the newly set secondary ranging point is single, the single secondary ranging point is determined as the used ranging point.

  When the secondary ranging point is determined as the used ranging point, as described above, the detection of the defocus amount at the determined secondary ranging point by the AF sensor module 22 and the focus lens 11f based on the defocus amount are performed. Displacement is performed.

  When the face detection function and the phase difference AF function are turned on in the second shooting mode, FIGS. 7 to 11 show the distance measuring points determined as the distance measuring points used for focusing the detected face. It explains using.

  When there is a fixed distance measuring point at a position very close to the detected face position, a single fixed distance measuring point is determined as the used distance measuring point. For example, as shown in FIG. 7, the fifth fixed distance measuring point FP5 is very close to the detected face position DP, and the distance is substantially equal to the distance between the face position DP and another fixed distance measuring point. If they are not equal, the fifth fixed distance measuring point FP5 is determined as the used distance measuring point.

  When there are only two fixed ranging points that are substantially equidistant from the detected face position in the same row, two primary ranging points are selected after the two fixed ranging points are selected as the primary ranging points. The midpoint of the distance point is set as the secondary distance measuring point. Since the set secondary ranging point is single, the single secondary ranging point is determined as the used ranging point.

  For example, as shown in FIG. 8, when only the fifth and sixth fixed distance measuring points FP5 and FP6 are selected as the primary distance measuring points with respect to the detected face position DP, the fifth and sixth The midpoint MP of the fixed distance measuring points FP5 and FP6 is set as the secondary distance measuring point. Since the set secondary ranging point is single, the midpoint MP is determined as the used ranging point.

  When there are only two fixed ranging points that are substantially equidistant from the detected face position in different rows, two primary ranging points are selected after the two fixed ranging points are selected as the primary ranging points. The distance point is set as the secondary distance measuring point as it is. Since there are a plurality of set secondary ranging points, the contrast value at the detected face position and the contrast value at the secondary ranging point are calculated. A secondary ranging point having a contrast value closer to the contrast value at the face position is determined as the used ranging point.

  For example, as shown in FIG. 9, when the second and fifth fixed distance measuring points FP2 and FP5 are selected as the primary distance measuring points with respect to the detected face position DP, the second and fifth fixed distance measuring points are selected. Distance measuring points FP2 and FP5 are set as secondary distance measuring points. Of the contrast values at the second and fifth fixed distance measuring points FP2 and FP5 set as the secondary distance measuring points, the secondary distance measuring points close to the contrast value at the face position DP are determined as the used distance measuring points. The

  If there are only two points in one row with a fixed ranging point that is substantially equidistant from the detected face position and one point in another row, the same after three points are selected as primary ranging points The midpoint of two primary ranging points on a row is set as a secondary ranging point, and one primary ranging point on another row is set as a secondary ranging point. Since there are a plurality of set secondary ranging points, the contrast value at the detected face position and the contrast value at the secondary ranging point are calculated. A secondary ranging point having a contrast value closer to the contrast value at the face position is determined as the used ranging point.

  For example, as shown in FIG. 10, when the second, fifth, and sixth fixed distance measuring points FP2, FP5, and FP6 are selected as the primary distance measuring points with respect to the detected face position DP, The fixed distance measuring point FP2 is set as the secondary distance measuring point. Further, the midpoint MP of the fifth and sixth fixed distance measuring points FP5 and FP6 is set as the secondary distance measuring point. Of the contrast values at the second fixed distance measurement point and the midpoint MP set as the secondary distance measurement point, the secondary distance measurement point close to the contrast value at the face position DP is determined as the use distance measurement point.

  If there are two points in a row with a fixed distance measuring point that is substantially equidistant from the detected face position and two points in another line, after four points are selected as primary distance measuring points, The midpoint of two primary ranging points on a row is set as a secondary ranging point, and the midpoint of two primary ranging points on another row is set as a secondary ranging point. Since there are a plurality of set secondary ranging points, the contrast value at the detected face position and the contrast value at the secondary ranging point are calculated. A secondary ranging point having a contrast value closer to the contrast value at the face position is determined as the used ranging point.

  For example, as shown in FIG. 11, the second, third, fifth, and sixth fixed ranging points FP2, FP3, FP5, and FP6 are selected as the primary ranging points with respect to the detected face position DP. In this case, the midpoint MP1 of the second and third fixed distance measuring points FP2 and FP3 is set as the secondary distance measuring point. Further, the midpoint MP2 of the fifth and sixth fixed distance measuring points FP5 and FP6 is set as the secondary distance measuring point. Of the contrast values at the midpoints MP1 and MP2 set as the secondary ranging points, the secondary ranging points close to the contrast value at the face position DP are determined as the used ranging points.

  Next, control of the operation of each part executed by the CPU 17 in the imaging mode will be described using the flowcharts of FIGS. Control in the shooting mode is started when the operation mode of the digital single-lens reflex camera 10 is switched to the shooting mode. The control in the shooting mode ends when the main power is turned off or the operation mode of the digital single lens reflex camera 10 is switched to another operation mode.

  In step S100, it is determined which of the first and second shooting modes is selected. If the first shooting mode is selected, the process proceeds to step S101. If the second shooting mode is selected, the process proceeds to step S105.

  In step S101, control is performed so that the main mirror 12 and the shutter 13 are closed. After the main mirror 12 and the shutter 13 are closed, the process proceeds to step S102. In step S102, it is determined whether or not the photometry switch and the distance measurement switch are in the ON state.

  When the photometry switch and the distance measurement switch are OFF, the process of step S101 is repeated until the photometry switch and the distance measurement switch are turned ON. When the photometry switch and the distance measurement switch are ON, the process proceeds to step S103.

  In step S103, the subject image is photometrically measured. Based on the photometric value, exposure adjustment such as adjustment of aperture, shutter speed, and / or sensitivity is performed. After exposure adjustment, the process proceeds to step S104.

  In step S104, the AF sensor module 22 is caused to detect the defocus amount with respect to the subject image at the set distance measuring point. Based on the detected defocus amount, the lens driving mechanism 18 is controlled to displace the focus lens 11f. After execution of such a phase difference AF function, the process proceeds to step S300.

  As described above, when the second shooting mode is selected in step S100, the process proceeds to step S105. In step S105, control is performed so that the main mirror 12 and the shutter 13 are opened. After the main mirror 12 and the shutter 13 are opened, the process proceeds to step S106.

  In step S106, the optical image of the subject reaching the image sensor 14 is received, and generation of an image signal of one frame is started every 1/60 seconds. In addition, after the image signal is generated, the DSP 16 performs image processing for moving images and transmits the image data to the LCD 21. Display of an image corresponding to the image data on the LCD 21 is started. When generation of an image signal of one frame and display on the LCD 21 are started, the process proceeds to step S107.

  In step S107, it is determined whether or not the photometry switch and the distance measurement switch are in the ON state. If the photometry switch and the distance measurement switch are OFF, the process of step S107 is repeated until the photometry switch and the distance measurement switch are turned ON. When the photometry switch and the distance measurement switch are ON, the process proceeds to step S108.

  In step S108, the same control as in step S103 is executed. That is, exposure adjustment such as photometry of the subject image, aperture, shutter speed, and / or sensitivity adjustment is performed. After exposure adjustment, the process proceeds to step S109.

  In step S109, it is determined whether or not the face detection function is ON. If the face detection function is ON, the process proceeds to step S110. If the face detection function is OFF, step S110 is skipped and the process proceeds to step S111.

  In step S110, the DSP 16 is caused to detect a face based on the image data, and a main subject is determined based on the detected face. When the main subject is determined, the process proceeds to step S111.

  In step S111, it is determined which of the contrast AF function and the phase difference AF function is selected as the AF to be executed. If the contrast AF function is selected, the process proceeds to step S112. If the phase difference AF function is selected, the process proceeds to step S113.

  In step S112, the contrast AF function is executed. That is, as described above, the contrast value is calculated based on the image data generated at each position while displacing the focus lens 11f, and the focus lens 11f is displaced to a position where the contract value is maximized. After completion of the contrast AF function, the process proceeds to step S300.

  As described above, when the phase difference AF function is selected in step S111, the process proceeds to step S113. In step S113, it is determined whether or not the distance measuring point is fixed, that is, whether or not the distance measuring point automatic selection function is ON.

  If the distance measuring point automatic selection function is ON, the process proceeds to step S114. If the automatic ranging point selection function is OFF, steps S114 and S200 are skipped and the process proceeds to step S115.

  In step S114, it is determined whether or not a face is detected in step S111. If a face is detected, the process proceeds to step S200. If no face is detected, the process proceeds to step S115.

  In step S200, a used distance measuring point for detecting the defocus amount is determined. After the used distance measuring point is determined, the process proceeds to step S115.

  In step S115, the main mirror 12 is controlled to close. Further, the generation of the image signal by the image sensor 14 is temporarily stopped. After the main mirror 12 is closed, the process proceeds to step S116.

  In step S116, the phase difference AF function is executed. That is, as described above, the defocus amount at the used distance measuring point determined in step S200 is detected, and the focus lens 11f is displaced based on the defocus amount. After completion of the phase difference AF function, the process proceeds to step S117.

  In step S117, control is performed to open the main mirror 12. Further, the generation of the image signal by the image sensor 14 is resumed. After the main mirror 12 is opened, the process proceeds to step S300.

  As described above, after the process of step S104, step S112, or step S117 ends, the process proceeds to step S300. In step S300, an imaging process is executed. After the process for imaging is completed, the process returns to step S100.

Next, FIG. 14 shows a subroutine for distance measuring point determination processing executed in step S200.
It demonstrates using the flowchart of these.

  In step S201, the face position determined as the main subject in step S110 is received from the DSP 16 as data. After receiving the position data, the process proceeds to step S202.

  In step S202, distances from the face position to the first to ninth fixed distance measuring points FP1 to FP9 are calculated. When the distances to all the fixed distance measuring points are calculated, the process proceeds to step S203.

  In step S203, the minimum value in the distance calculated in step S202 is detected. When there are a plurality of minimum values that completely match, one of the distances is detected as a single minimum value. Further, the comparison value is calculated by multiplying the minimum value by the first coefficient. When the comparison value is calculated, the process proceeds to step S204.

  In step S204, the difference between all the distances other than the distance detected as the minimum value and the minimum value is calculated. Further, the calculated difference is compared with the comparison value calculated in step S203. If there is no distance at which the calculated difference is less than the comparison value, the process proceeds to step S205. If there is even one distance at which the calculated difference is less than the comparison value, the process proceeds to step S206.

  In step S205, a fixed distance measuring point whose distance detected from the face position is the distance detected as the minimum value is selected. After selecting the fixed distance measuring point, the process proceeds to step S212.

  In step S206, the fixed distance measuring point where the distance detected as the minimum value is the distance from the face position, and the distance where the difference calculated in step S204 is less than the comparison value is the distance from the face position. Select the AF point as the primary AF point. After selecting the primary ranging point, the process proceeds to step S207.

  In step S207, a secondary ranging point is set based on the plurality of primary ranging points selected in step S206. After setting the secondary ranging point, the process proceeds to step S208.

  In step S208, it is determined whether or not there are a plurality of secondary ranging points set in step S207. If the set secondary ranging point is single, the process proceeds to step S209. If there are a plurality of set secondary ranging points, the process proceeds to step S210.

  In step S209, a single secondary ranging point is selected. After the secondary ranging point is selected, the process proceeds to step S212.

  In step S210, the DSP 16 calculates the contrast value at the face position read in step S201 and the contrast values at all the secondary ranging points set in step S207, and transmits them as data. After receiving the contrast value, the process proceeds to step S211.

  In step S211, a secondary ranging point having a contrast value closer to the contrast value at the face position is selected. After the secondary ranging point is selected, the process proceeds to step S212.

  In step S212, the fixed distance measurement point selected in step S205, the secondary distance measurement point selected in step S209, or the secondary distance measurement point selected in step S211 is determined as the use distance measurement point. After the used distance measuring points are determined, the subroutine for distance measuring point determination processing ends, and the process proceeds to step S115.

  Next, the subroutine of the imaging process executed in step S300 will be described using the flowchart of FIG.

  In step S301, it is determined whether or not the photographing switch is in an ON state. If the shooting switch is OFF, the process proceeds to step S302. If the shooting switch is ON, the process proceeds to step S304.

  In step S302, it is determined whether or not the photometry switch and the distance measurement switch are in the ON state. If the photometry switch and the distance measurement switch are in the OFF state, the process returns to step S301. When the photometry switch and the distance measurement switch are in the ON state, the process proceeds to step S303.

  In step S303, it is determined which of the first and second shooting modes is selected. If the first shooting mode is selected, the process returns to step S103. If the second shooting mode is selected, the process proceeds to step S105.

  As described above, if the photographing switch is in the ON state in step S301, the process proceeds to step S304. In step S304, it is determined which of the first and second shooting modes is selected.

  When the second shooting mode is selected, the process proceeds to step S305, and the main mirror 12 and the shutter 13 are controlled to be closed. After the main mirror 12 and the shutter 13 are closed, the process proceeds to step S306. If the first shooting mode is selected, step S305 is skipped and the process proceeds to step S306.

  In step S306, control is performed to open the main mirror 12. Further, the shutter 13 is controlled to open and close at the shutter speed adjusted in the exposure control. When the opening / closing control of the shutter 13 is finished, the process proceeds to step S307.

  In step S307, the image sensor 14 is caused to generate an image signal corresponding to the optical image of the subject received while the shutter 13 is opened in step S306. When the image signal is generated, the process proceeds to step S308.

  In step S <b> 308, the DSP 16 performs image processing for a still image and stores the image data in the image memory 20. When the image data is stored, the imaging process subroutine is terminated and the process returns to step S100.

  According to the distance measuring point determination system to which the first embodiment as described above is applied, a distance measuring point that uses a fixed distance measuring point or a secondary distance measuring point suitable for focusing the detected main subject. Can be determined as Therefore, it is possible to improve the focusing accuracy of the phase difference AF while executing a function of automatically detecting main subjects.

  In particular, if there are multiple fixed ranging points with the shortest distance from the main subject, a secondary ranging point is set, and if there are multiple secondary ranging points, one of the two based on the contrast value. Therefore, it is possible to determine a more suitable range-finding point.

  In addition, since a point between a plurality of primary ranging points having corresponding fixed points corresponding to the same line sensor is set as a secondary ranging point, a point closer to the main subject than the fixed ranging point is used. Confirmed as a point. Therefore, it is possible to further improve the focusing accuracy of the phase difference AF.

  Next, a ranging point determination system to which the second embodiment of the present invention is applied will be described. The distance measuring point determination system of the second embodiment is different from the first embodiment in the method of setting a secondary distance measuring point. Hereinafter, a description will be given focusing on differences from the first embodiment. In addition, the same code | symbol is attached | subjected to the site | part which has the same function as 1st Embodiment.

  In the digital single-lens reflex camera 10 of the second embodiment, the configuration and functions of parts other than the CPU 17 are the same as those of the first embodiment.

  In the second embodiment, in the state where the face detection function and the phase difference AF function are turned on, the use ranging point is determined as described below.

  Similar to the first embodiment, the CPU 17 calculates the distance between the light receiving position of the detected optical image of the face and the first to ninth fixed distance measuring points FP1 to FP9. Further, as in the first embodiment, the minimum value in the calculated distance is detected. Further, it is determined whether or not there is another fixed distance measuring point that is a distance that can be regarded as substantially equal to the detected minimum value.

  When there is no other fixed distance measuring point that is a distance that can be regarded as substantially equal to the minimum value, the fixed distance measuring point whose distance from the light receiving position is the minimum value is selected as in the first embodiment, Determined as the focus point to be used.

  When there is another fixed distance measuring point that is a distance that can be regarded as substantially equal to the minimum value, the primary distance measuring point is selected as in the first embodiment. When a plurality of primary ranging points are selected, unlike the first embodiment, all the selected primary ranging points are set as secondary ranging points as they are.

  When a plurality of secondary ranging points are set, as in the first embodiment, the CPU 17 controls the DSP 16 so that the contrast value at the secondary ranging point and the contrast value at the light receiving position of the optical image of the main subject are determined. Calculated based on the image signal. After the contrast value is calculated, a single secondary distance measuring point having a contrast value closest to the contrast value at the light receiving position in the optical image of the main subject is selected and determined as the distance measuring point to be used.

  According to the ranging point determination system to which the second embodiment as described above is applied, the secondary ranging point suitable for focusing the detected main subject can be determined as the used ranging point. Is possible. Therefore, it is possible to improve the focusing accuracy of the phase difference AF while executing the function of automatically detecting the main subject manually as in the first embodiment.

  In the first and second embodiments, whether or not the minimum value of the distances from the face position to the first to ninth fixed distance measuring points is substantially equal to the other distances is determined. Although it is the structure discriminate | determined based on (1) Formula, you may discriminate | determine based on another method. For example, a configuration in which a distance having a difference from a minimum value that is less than a threshold value is considered to be substantially equal to the minimum value may be used.

  In the first and second embodiments, the first coefficient is set to 0.05, but any value larger than 0 may be set. However, the first coefficient may be determined so that there are a maximum of two fixed distance measuring points that can be determined to be substantially equidistant from the face position, and a maximum of two points for different lines. preferable.

  In the first and second embodiments, nine fixed ranging points are predetermined, but the number is not limited to nine. If a plurality of fixed distance measuring points are determined in advance, it is possible to obtain the same effect as in the present application.

  In the first and second embodiments, the nine fixed distance measuring points are arranged in a matrix of 3 rows and 3 columns, but may not be arranged in a matrix.

  In the first and second embodiments, the defocus amount is calculated on the basis of the deviation from the fixed corresponding point between the position of the optical image passing through the left end of the exit pupil and the optical image passing through the right end of the exit pupil. Although it is a structure, it is not restricted to the optical image which passed the left end and right end of the exit pupil. For example, the configuration may be such that the defocus amount is calculated based on the deviation from the fixed corresponding point of the position of the optical image passing through the upper end of the exit pupil and the optical image passing through the lower end. Furthermore, a cross sensor is used to detect the defocus amount based on the deviation from the fixed corresponding point of the optical image passing through the left end and the right end and the deviation from the fixed corresponding point of the optical image passing through the upper end and the lower end. May be.

  In the present embodiment, the face is detected based on the image data. However, a configuration in which a shooting target belonging to a type other than the face is detected may be used. For example, the configuration may be such that an imaging object such as an animal such as a cat or a dog or a plant such as a flower is detected.

  In this embodiment, the present invention is applied to the digital single-lens reflex camera 10, but can be applied to any kind of digital camera having a function of detecting a main subject based on image data and a phase difference AF function. is there.

DESCRIPTION OF SYMBOLS 10 Digital single-lens reflex camera 11f Focus lens 12 Main mirror 14 Image pick-up element 16 Digital signal processor (DSP)
17 CPU
18 Lens drive mechanism 21 LCD
22 AF sensor module 22u Line sensor unit 22u1 to 22u3 1st to 3rd CCD line sensor 25 Frame line CA Shooting range DP Face position FP1 to FP9 1st to 9th fixed ranging point MP Midpoint ra Reference area sa Reference area

Claims (7)

Based on a plurality of fixed ranging points whose positions in the shooting range are determined in advance, ranging points are determined to determine the used ranging points used to focus the main subject that is the subject to be focused by phase difference AF. A system,
A plurality of line sensors that receive a part of the subject image within the photographing range for phase difference detection, and a specific position in the longitudinal direction is defined as the fixed distance measuring point;
An image sensor that receives an optical image of the imaging range and generates an image signal corresponding to the received optical image;
An image detection unit for detecting the main subject based on the image signal;
A position detection unit that detects a subject position that is a position within the photographing range of the main subject detected by the image detection unit;
A distance calculating unit that calculates a first distance, which is a distance between the subject position and the fixed ranging point, for each of the plurality of fixed ranging points;
A discriminator for discriminating whether or not there are a plurality of first distances that are substantially equal and minimum among the plurality of first distances calculated for each of the plurality of fixed ranging points; ,
A plurality of the first distances corresponding to a plurality of the first distances that are minimum when the determination unit determines that there are a plurality of the first distances that are substantially equal and minimum among the plurality of first distances; A first selection unit that selects the fixed ranging point as a primary ranging point;
When there are two primary ranging points determined by the same line sensor among the plurality of primary ranging points selected by the first selection unit, two of the two primary ranging points on the same line sensor are used. A point between the primary ranging points is set as a secondary ranging point, and the primary measurement determined by the same line sensor among the plurality of primary ranging points selected by the first selection unit. A setting unit for setting one primary distance measurement point on the same line sensor as the second distance measurement point when there is one distance point;
When a plurality of secondary ranging points are set by the setting unit, a contrast calculating unit that calculates a contrast value at the subject position and the plurality of secondary ranging points based on the image signal;
A ranging point determination system, comprising: a second selection unit that selects the secondary ranging point that has a contrast value closest to the contrast value at the subject position and determines the second ranging point as the used ranging point. In the case where all of the plurality of primary ranging points selected by the first selection unit are determined on the same line sensor, the setting unit selects points between all the primary ranging points. Is set as the secondary ranging point,
The second selection unit determines the secondary ranging point as the used ranging point when a single secondary ranging point is set by the setting unit. The ranging point setting system according to Item 1.   The ranging point setting system according to claim 1, wherein the setting unit sets the plurality of primary ranging points selected by the first selection unit to the plurality of secondary ranging points. . The second selection unit is configured to determine a single unit that is minimum when the determination unit determines that the first distances that are substantially equal and minimum among the plurality of first distances are single. The ranging point setting system according to any one of claims 1 to 3, wherein the fixed ranging point corresponding to one first distance is determined as the used ranging point.   The discriminating unit is configured such that the difference between the two first distances calculated for the two fixed distance measuring points is shorter than the first distance and the first coefficient in the two first distances. 5. The distance measuring point setting system according to claim 1, wherein the two first distances are determined to be substantially equal to each other when the distance is less than the product of. A plurality of line sensors that receive a part of the subject image within the shooting range for phase difference detection, and a specific position in the longitudinal direction is defined as a fixed distance measuring point;
An image sensor that receives an optical image of the imaging range and generates an image signal corresponding to the received optical image;
An image detection unit that detects a main subject that is a subject to be focused based on the image signal;
A first position detection unit that detects a subject position that is a position within the photographing range of the main subject detected by the image detection unit;
A distance calculating unit that calculates a first distance, which is a distance between the subject position and the fixed ranging point, for each of the plurality of fixed ranging points;
A discriminator for discriminating whether or not there are a plurality of first distances that are substantially equal and minimum among the plurality of first distances calculated for each of the plurality of fixed ranging points; ,
A plurality of the first distances corresponding to a plurality of the first distances that are minimum when the determination unit determines that there are a plurality of the first distances that are substantially equal and minimum among the plurality of first distances; A first selection unit that selects the fixed ranging point as a primary ranging point;
When there are two primary ranging points determined by the same line sensor among the plurality of primary ranging points selected by the first selection unit, two of the two primary ranging points on the same line sensor are used. A point between the primary ranging points is set as a secondary ranging point, and the primary measurement determined by the same line sensor among the plurality of primary ranging points selected by the first selection unit. A setting unit for setting one primary distance measurement point on the same line sensor as the second distance measurement point when there is one distance point;
When a plurality of secondary ranging points are set by the setting unit, a contrast calculating unit that calculates a contrast value at the subject position and the plurality of secondary ranging points based on the image signal;
A second selection unit that selects the secondary ranging point that is the contrast value closest to the contrast value at the subject position, and confirms it as a used ranging point;
A phase difference method is used to detect a position of a focus lens that brings the subject in focus by causing the line sensor to receive a subject located at the use ranging point determined by the second selection unit. A position detector of
An autofocus system comprising: a drive unit that displaces the focus lens at a position detected by the second position detection unit. A plurality of line sensors that receive a part of the subject image within the shooting range for phase difference detection, and a specific position in the longitudinal direction is defined as a fixed distance measuring point;
An image sensor that receives an optical image of the imaging range and generates an image signal corresponding to the received optical image;
An image detection unit that detects a main subject that is a subject to be focused based on the image signal;
A first position detection unit that detects a subject position that is a position within the photographing range of the main subject detected by the image detection unit;
A distance calculating unit that calculates a first distance, which is a distance between the subject position and the fixed ranging point, for each of the plurality of fixed ranging points;
A discriminator for discriminating whether or not there are a plurality of first distances that are substantially equal and minimum among the plurality of first distances calculated for each of the plurality of fixed ranging points; ,
A plurality of the first distances corresponding to a plurality of the first distances that are minimum when the determination unit determines that there are a plurality of the first distances that are substantially equal and minimum among the plurality of first distances; A first selection unit that selects the fixed ranging point as a primary ranging point;
When there are two primary ranging points determined by the same line sensor among the plurality of primary ranging points selected by the first selection unit, two of the two primary ranging points on the same line sensor are used. A point between the primary ranging points is set as a secondary ranging point, and the primary measurement determined by the same line sensor among the plurality of primary ranging points selected by the first selection unit. A setting unit for setting one primary distance measurement point on the same line sensor as the second distance measurement point when there is one distance point;
When a plurality of secondary ranging points are determined by the determining unit, a contrast calculating unit that calculates a contrast value at the subject position and the plurality of secondary ranging points based on the image signal;
A second selection unit that selects the secondary ranging point that is the contrast value closest to the contrast value at the subject position, and determines the used ranging point;
A phase difference method is used to detect a position of a focus lens that brings the subject in focus by causing the line sensor to receive a subject located at the use ranging point determined by the second selection unit. A position detector of
A drive unit that displaces the focus lens at a position detected by the second position detection unit.

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