JP2006023653A - Optical equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide optical equipment capable of performing efficient driving control of a focus lens. <P>SOLUTION: The optical equipment comprises a first focus detection means 9c which outputs a first signal, a second focus detection means 50 which generates a second signal indicating the contrast state of a subject and a control means 46 which decides the driving range of the focus lens based on the first signal and determines the focusing position on the basis of the second signal by performing scanning drive of driving the focus lens in the driving range by a specified amount. The control means changes a driving control sequence of the focus lens depending on the case that the detection position of the focus lens by a position detection means is within a driving range or without the same. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical apparatus that performs drive control of a focus lens.

  2. Description of the Related Art In recent years, so-called electronic cameras have been widely used in which a subject image is imaged on a semiconductor image sensor, for example, an image sensor image sensor by an imaging optical system, converted into an electrical signal, and still image data obtained thereby is recorded on a recording medium. It is becoming popular. Most of these electronic cameras have an autofocus (AF) function that automatically adjusts the focus on the subject. This AF function is called contrast AF or hill-climbing AF. The method is often used. This is because focus detection can be performed using the output of the image sensor that captures the captured image.

  On the other hand, in a single-lens reflex type camera using a silver salt film, a phase difference AF method is widely used in addition to contrast AF.

  In addition, a focus detection unit composed of an optical system and a light receiving sensor that performs focus detection by the phase difference AF method, a focus detection unit composed of an optical system and a light reception sensor that performs focus detection by the contrast AF method, and a focus in the phase difference AF method In some cases, the lens is driven to an in-focus position by using a combination of detection and focus detection in the contrast AF method (see, for example, Patent Document 1). That is, the lens is moved to the in-focus position by performing coarse adjustment by phase difference AF method focus detection and fine adjustment by contrast AF method focus detection.

  In addition, after moving the focus lens to the in-focus position obtained by the phase difference detection focus detection, the focus lens is moved within the front and back areas including this position to perform focus detection by the contrast detection method. Some devices detect the in-focus position (see, for example, Patent Document 2).

  In addition, after driving the photographic lens based on the phase difference detection signal, there is one that drives the imaging lens to the in-focus position based on the AF evaluation value corresponding to the contrast of the captured image (subject image) (for example, patents). Reference 3).

In addition, there is a type in which a plurality of distance measuring means has a plurality of distance measuring areas, and distance measurement is performed with reference to previous distance measurement area information when the distance measuring means is switched to another distance measuring means (for example, (See Patent Document 4).
Japanese Patent Laid-Open No. 7-43605 (paragraph number 0007, FIG. 1 etc.) Japanese Patent Laid-Open No. 9-181954 (paragraph numbers 0038, 0039, FIG. 4, FIG. 9, etc.) JP 2001-281530 A (paragraph numbers 0058 and 0060, FIG. 5 and the like) Japanese Patent Laid-Open No. 10-39196 (paragraph numbers 0036 to 0048, FIG. 5 etc.)

  However, Patent Document 1 and Patent Document 3 do not reflect the focus detection result by the phase difference detection method in the lens drive control in the focus detection by the contrast detection method. Further, it is not disclosed in a specific lens driving sequence when performing focus detection by contrast detection.

  In Patent Document 2, the lens is moved to a focus position obtained by focus detection using the phase difference detection method, and then moved to a position where focus detection using the contrast detection method is started. Therefore, focus detection is performed. In some cases, a time loss occurs. In addition, this document does not disclose any lens driving range when performing focus detection by the contrast detection method.

  Further, in Patent Document 4, it is the distance measurement area information that is referred to by the next distance measurement means, and the next distance measurement means does not change the distance measurement sequence.

  The optical apparatus of the present invention includes first focus detection means for outputting a first signal obtained by photoelectrically converting a plurality of optical images obtained by dividing a light beam from a photographing optical system including a focus lens. A second focus detection unit that generates a second signal indicating a contrast state of the subject image from a video signal obtained by photoelectrically converting an optical image formed by the photographing optical system; and a first signal based on the first signal. Control means for determining a focus lens drive range, performing scan drive for driving the focus lens by a predetermined amount within the drive range to obtain a focus position based on the second signal, and position detection means for detecting the position of the focus lens And the control means changes the focus lens drive control sequence depending on whether the position detected by the position detection means is within the drive range or outside the drive range. It is characterized in.

  According to the present invention, it is possible to perform appropriate drive control of the focus lens depending on whether the detection position of the focus lens is within the drive range or outside the drive range.

  Examples of the present invention will be described below.

  FIG. 1 is a diagram illustrating a main configuration of a camera system that is Embodiment 1 of the present invention. The camera system of the present embodiment includes a camera main body (optical device) 100 and a lens device 101 attached to the camera main body 100.

  Reference numerals 1 and 2 denote photographing lenses. Specifically, the photographing lens 1 is a zoom lens that can move in the optical axis L direction and change the focal length of the photographing optical system, and the photographing lens 2 moves in the optical axis L direction and performs focus adjustment. It is. Reference numeral 3 denotes a stop as a light amount adjusting member that adjusts the amount of light incident on the image plane in accordance with the luminance of the subject. Here, the photographing lenses 1 and 2 and the diaphragm 3 are provided in the lens device 101.

  Reference numeral 22 denotes a position detection unit (position detection means) that detects the position of the focus lens 2 and outputs the detection result to the system controller 46.

  Reference numeral 5 denotes a mirror which is disposed in the photographing optical path when the camera body 100 is in the non-photographing state, and is in a position retracted from the photographing optical path when the camera body 100 is in the non-photographing state. The mirror 5 has a half mirror 5a and a sub mirror 5b.

  When in the non-shooting state, the half mirror 5a transmits a part of the light beam that has passed through the photographing lens 1 and the focus lens 2 to be directed toward the image plane, and reflects the remaining light beam to reflect the remaining light beam. The light is guided to a finder optical system (not shown) provided in 100. The sub-mirror 5b disposed on the image plane side with respect to the half mirror 5a reflects the light beam transmitted through the half mirror 5a and guides it to the focus detection unit 9 described later when in the non-photographing state.

  Reference numerals 6 and 7 respectively denote an optical axis of a light beam directed to the image plane among light beams divided by the half mirror 5 and an optical axis of a light beam directed to the focus detection unit 9. Reference numeral 8 denotes an image sensor (for example, a CCD or CMOS sensor) that photoelectrically converts a subject image (optical image) formed by the photographing lenses 1 and 2.

  Reference numeral 10 denotes a shutter (focal plane shutter) that limits the amount of light incident on the image sensor 8 by opening and closing the front curtain and the rear curtain. Here, when data is read out from the image sensor 8, the shutter 10 is closed.

  A focus detection unit 9 receives the light beam (AF light beam) reflected by the mirror 5b and detects the focus state of the photographing optical system (including the photographing lenses 1 and 2) by the phase difference detection method. Here, 9a is an AF mirror (a mirror with high reflectivity), which reflects the AF light flux from the mirror 5b and guides it to an AF sensor described later. Reference numeral 9b denotes a separator lens for dividing the pupil of the AF light beam. An AF sensor 9c receives the AF light beam divided by the separator lens 9b, and detects a focus adjustment state (defocus amount) by a phase difference detection method.

  FIG. 5 is a block diagram showing the configuration of the camera system of this embodiment. Here, the same members as those described in FIG.

  The system controller 46 controls driving of the image sensor 8 via the imaging circuit 30. The signal read from the image sensor 8 is converted into a digital signal by the A / D converter 31 and subjected to predetermined image processing (color processing or the like) by the image processing circuit 32. The image signal generated by the image processing circuit 32 is temporarily stored in the buffer memory 33.

  Here, in the case of saving image data, the data stored in the buffer memory 33 is compressed by the JPEG method or the like in the compression / decompression circuit 34, and then recorded via a disk drive 35 (for example, a semiconductor memory or magnetic field). Disc) 36 is recorded.

  The image data recorded on the recording medium 36 is decompressed by the compression / decompression circuit 34 and stored in the buffer memory 33, and then passed through the VRAM (video RAM) 42 and then by the display control circuit 43 by the display unit (EVF, Electronic View Finder) 44 displays it as a photographed image.

  The output signal of the AF sensor 9c is input to the AF control unit 45 in the system controller 46 and used for AF control by the phase difference method. The AF control unit 45 in the system controller 46 performs AF control using a contrast method based on the output from the image sensor 8.

  The system controller 46 performs control in the camera system, receives instructions from the power switch 49, the release switch 41, and the zoom switch 48, and performs operations according to these instructions.

  The release switch 41 is a switch SW1 for instructing start of a shooting preparation operation (photometry operation, focus adjustment operation, etc.) and a shooting operation (recording of a signal read from the image sensor 8 on the recording medium 36, etc.). And a switch SW2 for instructing. The zoom switch 47 is a switch for instructing switching of the focal length of the photographing optical system.

  The system controller 46 drives the focus lens 2 by performing drive control of the focus motor 21 via the focus drive circuit 19 in accordance with AF control in the AF control unit 45.

  Further, when receiving an instruction from the zoom switch 48, the system controller 46 drives the zoom lens 1 by performing drive control of the zoom motor 40 via the zoom drive circuit 39. Here, the system controller 46 detects the position of the zoom lens 1 (focal length of the photographing optical system) via the focal length detection circuit 47.

  In the case where a controller is provided in each of the camera body 100 and the lens apparatus 101, some of the operations of the system controller 46 are performed by the controller in the camera body 100, and other operations are performed by the lens apparatus 101. Can be done by the controller inside.

  FIG. 2 is a diagram for explaining the principle of focus detection by the phase difference detection method. Here, the AF luminous flux divided by the separator lens 9b is received by the photoelectric conversion element arrays 9d1 and 9d2 provided on the AF sensor 9c.

  FIG. 2A shows the position of the focus lens 2 and the output of the AF sensor 9c when the photographing optical system is in focus. At this time, the two light beams divided by the separator lens 9b form an image at the center of the photoelectric conversion element arrays 9d1 and 9d2.

  On the other hand, when the focus lens 2 moves to the right or left side of the drawing from the in-focus position shown in FIG. 2A, as shown in FIGS. 2B and 2C, on the photoelectric conversion element arrays 9d1 and 9d2. Is moved to the end side of the photoelectric conversion element arrays 9d1 and 9d2. That is, in the state shown in FIG. 2B (the state of the front pin), the imaging positions of the two light beams are displaced in a direction approaching each other. In the state shown in FIG. 2C (the state of the rear pin), the imaging positions of the two light beams are displaced in directions away from each other.

  For this reason, a signal for driving the focus lens 2 to the in-focus position can be specified by detecting and calculating the shift amount and the shift direction of the imaging position.

  FIG. 3 is a block diagram showing a configuration for performing a focus detection operation by the phase difference detection method.

  Charge accumulation in the photoelectric conversion element arrays 9d1 and 9d2 until the level of the output signal of the AF sensor 9c reaches a predetermined value or until a predetermined time (Tmax) determined by the accumulation time measurement unit 18 in the system controller 46 elapses. When the charge accumulation is completed, the output signal of the AF sensor 9 c is quantized by the signal processing circuit 15 and then input to the system controller 46.

  The defocus amount calculation unit 16 in the system controller 46 performs a shift amount calculation using the quantum information quantized by the signal processing circuit 15 and normalizes the calculation result as a defocus amount Df.

  Here, in order to determine whether or not the in-focus state is maintained, that is, whether or not the subject is moving, it is determined by repeatedly performing focus detection by a phase difference detection method at intervals of a predetermined time. be able to.

  On the other hand, the focus detection by the contrast detection method is performed by the AF evaluation signal generation unit 50 in the system controller 46 extracting a high frequency component from the output signal of the image sensor 8 and generating an AF evaluation value. Then, focusing is obtained by moving the focus lens 2 so that the peak of the AF evaluation value is maximized. In focus detection by the contrast detection method, since the image sensor 8 for capturing a captured image is used as a sensor, focus detection can be performed with extremely high accuracy compared to focus detection by the phase difference detection method. The AF evaluation signal generation unit 50 may be provided outside the system controller 46.

  FIG. 4 shows a schematic diagram of an imaging region in the imaging device. In this embodiment, in order to speed up the reading operation, the reading operation is performed at a normal speed in the specific area 25 in the imaging area, and the reading speed in the specific area is set in the other areas 26 and 27. The reading operation is performed at a faster speed. The system controller 46 controls driving of the image sensor 8 via the imaging circuit 30 so as to perform the above-described operation. As described above, by increasing the reading speed in the other areas 26 and 27, the partial reading operation can be speeded up.

  FIG. 6 is a flowchart showing a photographing operation in the camera system of the present embodiment. When the power switch 49 is turned on, the camera system is activated (S1), and the system controller 46 detects various switches (S2).

  Then, it is determined whether or not SW1 of the release switch 41 is on (S3). If SW1 is not on, the process returns to step S2. If SW1 is in the on state, photometry (S4) is performed using the image sensor 8. That is, the subject light reaches the image sensor 8 and the subject brightness is measured based on the output of the image sensor 8.

  Then, the system controller 46 determines the aperture value based on the photometric result in step S4, and controls the drive of the aperture 3 so as to be the aperture value (S5). Next, the output of the focal length detection circuit 47 is output. Based on this, the focal length of the photographing optical system is detected (S6).

  Then, the process proceeds to the phase difference AF routine to perform focus detection by the phase difference detection method (S7). The phase difference AF routine will be described later with reference to FIG.

  Next, the system controller 46 calculates the movement stop position of the focus lens 2 for bringing the photographing optical system into focus based on the detection result (defocus amount) in the phase difference AF routine (S7) ( S8). This movement stop position is a focus position of the focus lens 2 obtained by focus detection by the phase difference detection method (second focus position, hereinafter referred to as a phase difference focus position). This phase difference focus position The information regarding is stored in a memory or the like in the system controller 46.

  Then, the process proceeds to a scan range setting routine (S9). Here, in the scan range setting routine, as will be described later, based on the aperture value set in step S5 and the focal length detected in step S6, focus adjustment by the contrast detection method (hereinafter referred to as TV-AF). Sets the scan range (drive range of the focus lens) when performing. Details of the scan range setting routine will be described later with reference to FIG.

  After the scan range setting routine (S9) is completed, the moving direction of the focus lens 2 is set (S10). Specifically, the rotation direction Mr of the focus motor 21 is set to the rotation direction Ro corresponding to the movement direction of the focus lens 2 (S10).

  Next, it is determined whether or not the current position of the focus lens 2 detected by the position detection unit 22 is within the scan range in Tv-AF set in step S9 (scan range setting routine) (S11). . If the current position of the focus lens 2 is within the scan range, the focus lens 2 is moved to a position corresponding to one end of the scan range set in step S9 (S12).

  Next, the process proceeds to the first TV-AF routine (S13). The first TV-AF routine will be described later with reference to FIG.

  On the other hand, when the current position of the focus lens 2 is not within the scan range (S11), the focus lens 2 is driven and moved in a direction approaching the scan range (S15). Then, it is determined whether or not the current position of the focus lens 2 is within the scan range (S16).

  If the current position of the focus lens 2 is outside the scan range (S16), the focus lens 2 is continuously driven to approach the scan range (S15). On the other hand, if the current position of the focus lens 2 is within the scan range, the process proceeds to the second TV-AF routine to perform the TV-AF operation from this position (S17). The second TV-AF routine will be described later with reference to FIG.

  Next, the system controller 46 (AF control unit 45) completes the processing in the first TV-AF routine (S13) and the second TV-AF routine (S17), and then the photographing optical system is in a focused state. It is determined whether or not (S14). Here, if not in focus, the process returns to step S2 to repeat the above-described operation. On the other hand, if the photographing optical system is in focus, focus display is performed (S18). Specifically, information indicating that the photographing optical system is in focus is displayed in the display unit 44 and the viewfinder field of view.

  Next, it is determined whether or not SW2 of the release switch 41 is in an on state. If SW2 is in an off state, the process returns to step S2 to repeat the above-described operation (S19). On the other hand, when SW2 is on (S19), exposure control is performed (S20). Specifically, the image sensor 8 is exposed by opening and closing the shutter 10, and predetermined processing (A / D converter 31 and image processing circuit 32) is performed on the signal read from the image sensor 8. And processing in the compression / decompression circuit 34), the data is recorded on the recording medium 36. Then, the shooting operation ends.

  FIG. 7 is a flowchart showing a phase difference AF routine in the present embodiment. When focus detection by the phase difference detection method is started, charge accumulation in the AF sensor 9c (photoelectric conversion element arrays 9d1, 9d2) is started (S21), and the elapse of a predetermined time as described with reference to FIG. The storage operation is completed after waiting (S22). Then, the defocus amount calculation unit 16 (see FIG. 3) in the system controller 46 calculates the defocus amount (Df) based on the output of the AF sensor 9c (S23). The system controller 46 calculates the phase difference focus position of the focus lens 2 based on the defocus amount (S8 in FIG. 6).

  FIG. 8 is a diagram showing a scan range setting routine in the present embodiment. Here, in the scan range setting routine, the scan range is set based on the aperture value determined in step S5 of FIG. 6 and the focal length information detected in step S6.

  First, when the scan range setting routine is started, it is determined whether or not the focal length L obtained in step S6 in FIG. 6 is smaller than a predetermined focal length L0 (S26). When the focal length L is smaller than the predetermined focal length L0 (S26), the TV-AF scan range WL calculated from the focal length is set to n1 times the moving step interval B (S27). If the focal length L is greater than the predetermined focal length L0 (S26), the scan range WL is set to n2 times the moving step interval B (S28).

  Here, the movement step interval B is the minimum drive amount of the focus lens 2, for example, a drive amount corresponding to one step when a stepping motor is used as the focus motor 21. Further, n1 and n2 are different numerical values and satisfy the relationship n1> n2.

  When the focal length L is longer than the predetermined focal length L0, the depth of field becomes shallower than when the focal length L is shorter than the predetermined focal length L0. Detection can be performed. In this embodiment, therefore, an efficient TV-AF operation corresponding to the focal length can be performed by changing the scan range according to the focal length of the photographing optical system as described above. That is, unnecessary lens driving is omitted by making the scan range when the focal length L is longer than the predetermined focal length L0 narrower than the scan range when the focal length L is shorter than the predetermined focal length L0. Efficient TV-AF operation can be performed. Then, the time required for the TV-AF operation can be shortened.

  Next, it is determined whether or not the aperture value A determined in step S5 in FIG. 6 is smaller than a predetermined aperture value A0 (S29). Here, when the aperture value A is smaller than the aperture value A0, the TV-AF scan range WA calculated from the aperture value is set to n3 times the moving step interval B (S30). On the other hand, if the aperture value A is larger than the aperture value A0, the TV-AF scan range WA calculated from the aperture value is set to n4 times the moving step interval B (S31).

  Here, n3 and n4 are different numerical values, and are numerical values satisfying n3 <n4.

  When the aperture value A is smaller than the predetermined aperture value A0 (the aperture diameter is large), the depth of field becomes shallower than when the aperture value A is larger than the predetermined aperture value A0. It is possible to detect the focus even if the value is narrowed. Therefore, in the present embodiment, by changing the scan range according to the aperture value A as described above, an efficient TV-AF operation according to the aperture value can be performed. In other words, unnecessary lens driving is omitted by making the scan range when the aperture value A is smaller than the predetermined aperture value A0 narrower than the scan range when the aperture value A is smaller than the predetermined aperture value A0. Efficient TV-AF operation. Then, the time required for the TV-AF operation can be shortened.

  Next, the scan range WL determined in step S27 or step S28 is compared with the scan range WA determined in step S30 or step S31 (S32). Here, when WL> WA (S32), the final scan range W in the TV-AF is set as the scan range WL (S33). If WL ≦ WA (S32), the final scan range W in TV-AF is set as the scan range WA (S34).

  Based on the scan range W set in step S33 or step S34, the absolute position to which the focus lens 2 should move is calculated (S35), and the process returns to the main flowchart (step S10 in FIG. 6) (S36).

  FIG. 9 shows a flowchart of the first TV-AF routine. When the first TV-AF routine starts, photometry using the image sensor 8 is first performed in order to prepare for exposure and to perform TV-AF (S40). Next, the rotation direction of the focus motor 21 is set (S41). Specifically, the rotation direction of the focus motor 21 is set to the rotation direction R0 so that the focus lens 2 can be moved in the direction opposite to the lens driving direction in step S12 in FIG. 6 (S41).

  The focus lens 2 is driven in the rotation direction set in step S41, and the focus lens 2 is moved by the above-described moving step interval B (S42). Then, it is determined whether or not the focus lens 2 is at a position corresponding to one end of the scan range (S43). If the focus lens 2 is not at a position corresponding to the one end, the drive of the focus lens 2 is stopped and the focus motor 21 is rotated. The direction is set to the rotation direction R0 (S44).

  Next, the exposure conditions for the image sensor 8 are set (S45), and the image sensor 8 is exposed and charged (S46). Then, the accumulated charge is read from the image sensor 8 (S47), and the AF evaluation signal generator 50 generates an AF evaluation signal (S48).

  Next, the focus lens 2 is further moved by the moving step interval B (S49). The operations from step S45 to step S50 are repeated until the focus lens 2 moves to a position corresponding to the other end of the scan range.

  When the focus lens 2 moves to a position corresponding to the other end of the scan range, the rotation direction of the focus motor 21 is set so that the focus lens 2 moves to one end side of the scan range (S51). Then, by driving the focus motor 21, the focus lens 2 is moved from the other end side to the one end side of the scan range to move to a position where the AF evaluation value shows the maximum value (S52).

  The above-described operation will be specifically described with reference to FIG. FIG. 12 is a diagram for explaining the processing in step S12 of FIG. 6 and the driving of the focus lens by the first TV-AF routine. The horizontal direction in FIG. 12 indicates the position of the focus lens 2.

  The position indicated by a indicates the current position of the focus lens 2 before performing focus detection by the phase difference detection method in step S7 of FIG. First, in a state where the focus lens 2 is at the position “a”, when the process proceeds to the phase difference AF routine (FIG. 7) in step S7, the phase difference in-focus position of the focus lens 2 is specified, and data relating to this position is stored in the system controller 46. Store in the internal memory.

  Here, it is assumed that the phase difference in-focus position determined based on the defocus amount obtained in step S23 in FIG. 7 is the position indicated by b in FIG.

  If the phase difference focus position b of the focus lens 2 is known, the position range in which the focus lens 2 is moved can be found from the scan range W determined in step S9 (scan range setting routine of TV-AF) in FIG. The positions corresponding to both ends of the scan range W are determined by setting the center of the scan range W as the phase difference focus position b as shown in FIG. That is, the distance (distance A) from the phase difference in-focus position b to the position c corresponding to one end of the scan range W, and the distance from the phase difference in-focus position b to the position d corresponding to the other end of the scan range W ( Distance A) is equal. In the first TV-AF operation, the focus lens 2 is driven within the position range determined as described above.

  As shown in FIG. 12, when it is determined that the current position a is within the scan range W based on the current position a, the phase difference focusing position b, and the scan range W of the focus lens 2 (S11 in FIG. 6). The focus lens 2 is moved to the position c (S12 in FIG. 6). This operation is shown in IV.

  Next, the focus motor 21 is rotated in the reverse direction (S41 in FIG. 9), and the operation indicated by the arrow V is performed on the focus lens 2 (S42). That is, the focus lens 2 is moved from the position c to the position d. In the operation indicated by the arrow V, the processes in steps S45 to S49 are repeated for the number of black circles. Here, the interval between the positions of the adjacent black circles indicates the moving step interval B described above.

  Next, based on AF evaluation values obtained at a plurality of black circle positions, a position e having the highest AF evaluation value in the scan range W is calculated and the focus motor 21 is reversed (S51). The focus lens 2 is moved to the position e (S52). This operation is indicated by an arrow VI in FIG. Here, the position e indicates a focus position (first focus position, hereinafter referred to as a contrast focus position) obtained by the TV-AF operation. Note that the contrast focus position may not match the phase difference focus position.

  Here, the calculation of the AF evaluation value is performed when the focus lens 2 is in the position of the black circle as described above, but the AF evaluation value between the two positions based on the AF evaluation value obtained at each position. Is also computed. As a result, AF evaluation values in the entire region of the scan range W are obtained.

  On the other hand, when the current position a of the focus lens 2 is between the phase difference focusing position b and the position d, first, the focus lens 2 is moved to the position d. Then, within the scan range W, the focus lens 2 is stopped at the position of the black circle, and the AF evaluation value is acquired. When the focus lens 2 is moved to the position c, the focus motor 21 is rotated in the reverse direction to move to a position (contrast focus position) where the AF evaluation value is the highest.

  Next, the flowchart of the second TV-AF routine of FIG. 10 will be described with reference to FIG. Here, FIG. 11 is a diagram for explaining the operation from step S15 to step S17 in FIG. The horizontal direction in FIG. 11 indicates the position of the focus lens 2.

  The position indicated by a1 in FIG. 11 indicates the current position of the focus lens 2 before performing the processing of Step S7 in FIG. 6 (phase difference AF routine). Here, the current position a1 is located outside the scan range W.

  When the process proceeds to the phase difference AF routine (FIG. 7) in step S7 while the focus lens 2 is at the position a1, the defocus amount in the photographing optical system is calculated by focus detection by the phase difference detection method.

  Next, in step S8 of FIG. 6, the phase difference focusing position b1 (see FIG. 11) of the focus lens 2 is specified based on the current position a of the focus lens 2 and the defocus amount.

  When the phase difference focus position b1 of the focus lens 2 is known, as described above, the position range in which the focus lens 2 is moved from the scan range W determined in step S9 (TV-AF scan range setting routine) in FIG. I understand. As shown in FIG. 11, the positions corresponding to both ends of the scan range W are determined by setting the center of the scan range W as the phase difference focus position b1.

  As shown in FIG. 11, when it is determined that the current position a1 is located outside the scan range W based on the current position a1, the phase difference focusing position b1, and the scan range W of the focus lens 2 (FIG. 6). S11), the focus lens 2 is moved to a position c1 corresponding to one end of the scan range W by the process of step S15 in FIG. This operation is indicated by an arrow I in FIG.

  Next, in step S16 of FIG. 6, it is determined whether or not the position of the focus lens 2 is within the scan range W. Here, when it is determined that the current position falls within the scan range W, the focus lens 2 has moved to the position c1. Then, the process proceeds to the second TV-AF routine of step S17.

  In the second TV-AF routine (FIG. 10), after photometry (S60, corresponding to S40 in FIG. 9), the focus motor 21 is rotated so as to drive the focus lens 2 in the same direction as the lens drive direction in step S15. A direction is set (S41). Then, the operation shown in II of FIG. 10 is performed on the focus lens 2.

  That is, the focus lens 2 is stopped at the position indicated by the black circle, the image sensor 8 is exposed, and the AF evaluation value is calculated based on the output of the image sensor 8 (S62 to S65). Then, while repeating this operation, the focus lens 2 is moved from the position c1 to the position d1.

  Here, the interval between the positions of the adjacent black circles indicates the moving step interval B described above.

  Next, based on the AF evaluation values at the positions of a plurality of black circles as described above, the position e1 having the highest AF evaluation value within the scan range is calculated, and the setting is made so that the focus motor 21 is rotated in the reverse direction. Perform (S68). Here, the position e1 indicates the focus position (contrast focus position) of the focus lens 2 obtained by the TV-AF operation.

  Then, by driving the focus motor 21, the focus lens 2 is moved from the position d1 to the position e1. This operation is indicated by an arrow III in FIG. As a result, the photographing optical system is brought into focus. Each process from step S62 to step S69 corresponds to each process from step S45 to step S52 in FIG.

  On the other hand, when the current position a1 of the focus lens 2 before performing the process of step S7 in FIG. 6 is on the right side in FIG. 11 with respect to the position d1, first, the focus lens 2 is moved to the position d1. Then, the focus lens 2 is moved from the position d1 to the position c1 while acquiring the AF evaluation value at the position of the black circle in the scan range W. Next, the focus lens 2 at the position c1 is moved to a position where the AF evaluation value is the highest. As a result, the photographing optical system is brought into focus.

  According to the present embodiment, the phase difference focus position is specified by focus detection by the phase difference detection method, and the focus detection by the TV-AF is performed within the scan range including the phase difference focus position. Good focus detection can be performed. As a result, the lens is driven based on focus detection by the phase difference detection method as in the prior art, and the time required for focus detection (in-focus state) is compared to the case of performing lens driving for focus detection by the contrast detection method. Time). That is, in this embodiment, the focus lens is not moved to one end of the scan range after the focus lens is moved to the phase difference focus position as in the prior art, but is moved to the end of the scan range including the phase difference focus position. Since the TV-AF operation is then performed within the scan range, the lens drive amount can be reduced and the time required for focus detection can be shortened.

  Next, a camera system that is Embodiment 2 of the present invention will be described. Since the configuration of the camera system of the present embodiment is the same as the configuration of the camera system of Embodiment 1, description thereof is omitted. Moreover, in the following description, only a different part from Example 1 is demonstrated.

  FIG. 13 is a diagram illustrating a scan range setting routine according to the present embodiment (corresponding to FIG. 8 of the first embodiment).

  Here, by using the result (output of the AF sensor 9c) in the phase difference AF routine (S7) of FIG. 6 performed before the scan range setting routine of FIG. 13, the contrast of the subject becomes the first predetermined value. Or higher. Whether or not the contrast is high can be determined based on the height h of the output waveform of the AF sensor 9c as shown in FIG. That is, if the height h of the output waveform is higher than the second predetermined value (a value corresponding to the first predetermined value), the contrast is higher than the first predetermined value, and the height h is the second predetermined value. If it is lower than that, the contrast will be lower than the first predetermined value.

  In FIG. 13, the system controller 46 determines whether or not the contrast h of the subject is higher than the first predetermined value h0 based on the output of the AF sensor 9c in the phase difference AF routine (S80).

  If the contrast h is higher than the first predetermined value h0, the scan range WC is set to a range that is n5 times the movement step interval B (S81). If the contrast h is lower than the first predetermined value h0, the scan range WC is set to a range n6 times the movement step interval B (S82). Here, n5 and n6 are different numerical values, and are numerical values satisfying n5 <n6.

  Then, the final scan range W is set to the scan range WC determined in step S81 or step S82 (S83), and the process proceeds to step S10 in FIG.

  In this embodiment, as described above, the scan range WC is changed depending on whether the contrast of the subject is higher or lower than the first predetermined value. That is, when the contrast is high, the scan range is narrower than when the contrast is low. Here, when the contrast is high, focus detection by TV-AF can be performed even if the scan range is narrow. Then, the total driving amount of the focus lens 2 in the TV-AF is reduced by the amount that the scan range is narrowed, and a quick AF operation can be performed.

  Next, a camera system that is Embodiment 3 of the present invention will be described with reference to FIGS. Here, FIG. 14 shows a flowchart of a first TV-AF routine in the present embodiment (a flowchart corresponding to FIG. 9 of the first embodiment), and FIG. 15 shows a second TV-AF routine in the present embodiment. (A flowchart corresponding to FIG. 10 of the first embodiment). The configuration of the camera system of the present embodiment is the same as that of the camera system of the first embodiment, and operations other than the operations described below are the same as the operations described in the first embodiment.

  The flowcharts shown in FIGS. 14 and 15 are obtained by changing a part of the flowcharts shown in FIGS. 9 and 10. Specifically, in FIG. 14, steps S54 to S56 are added between step S49 and step S50 of FIG. In FIG. 15, steps S71 to S73 are added between step S66 and step S67 of FIG. 14 and 15, the same processes as those described in FIGS. 9 and 10 are denoted by the same reference numerals.

  Steps S45 to S50 in FIG. 14 show the scanning operation by the TV-AF. In this embodiment, the in-focus state is confirmed again based on the phase difference detection method during the scanning operation. Yes.

  In the TV-AF scanning operation, when the focus lens 2 is stopped at a predetermined position (position indicated by a black circle in FIG. 12) within the scan range (S49), is the focus lens 2 moved to the phase difference in-focus position? It is determined whether or not (S54). Here, since the information on the phase difference in-focus position is stored in advance in step S8 of FIG. 6, it is determined whether or not the focus lens 2 has moved to the in-focus position by using this in-focus position information. can do.

  In step S54, if the focus lens 2 has not passed the phase difference in-focus position, it is determined whether or not the focus lens 2 is located within the scan range (S50).

  On the other hand, if the focus lens 2 has passed the phase difference in-focus position in step S54, the process proceeds to the phase difference AF routine (FIG. 7) again (S55). Then, based on the focus detection result (defocus amount) by the phase difference detection method, it is determined whether or not the phase difference in-focus position is within the previously set scan range (S56).

  If the phase difference in-focus position is within the scan range, the process proceeds to step S50. On the other hand, when the phase difference in-focus position is outside the scan range, the subject has moved greatly, and even if the TV-AF operation is performed within the scan range, the subject cannot be focused. Return to step S8.

  Further, steps S62 to S67 in FIG. 15 show the scanning operation by the TV-AF, but the in-focus state is confirmed again based on the phase difference detection method during the scanning operation.

  In the TV-AF scanning operation, when the focus lens 2 is stopped at a predetermined position (indicated by a black circle in FIG. 11) within the scan range (S66), has the focus lens 2 moved to the phase difference in-focus position? It is determined whether or not (S71).

  Here, if the focus lens 2 has not passed the phase difference in-focus position, it is determined whether or not the focus lens 2 is located within the scan range (S67). On the other hand, if the focus lens 2 has passed the phase difference focusing position (S71), the process proceeds to the phase difference AF routine (FIG. 7) again (S72). Then, based on the focus detection result (defocus amount) by the phase difference detection method, it is determined whether or not the phase difference in-focus position is within the previously set scan range (S73).

  If the phase difference in-focus position is within the scan range, the process proceeds to step S67. On the other hand, when the phase difference in-focus position is outside the scan range, the subject has moved greatly, and even if the TV-AF operation is performed within the scan range, the subject cannot be focused. Return to step S8.

  In the present embodiment, as described above, focus detection by the phase difference detection method is performed again during the TV-AF operation. As a result, if the phase difference in-focus position is out of the scan range during the TV-AF operation due to the subject moving from its original position, the TV-AF operation is stopped, which is useless. The AF operation time can be omitted. Since the scan range is set again and the TV-AF operation is performed, an efficient AF operation according to the movement of the subject can be performed.

1 is a configuration diagram of a camera system that is Embodiment 1 of the present invention. FIG. The principle explanatory view of focus detection by a phase difference detection method. The block diagram which shows the structure of the part which performs the focus detection by a phase difference detection system. Schematic of the imaging area in an image sensor. 1 is a block diagram illustrating a configuration of a camera system according to Embodiment 1. FIG. 6 is a flowchart illustrating a shooting operation in the camera system according to the first exemplary embodiment. 5 is a flowchart illustrating a phase difference AF routine in the first embodiment. 6 is a flowchart illustrating a scan range setting routine according to the first exemplary embodiment. 3 is a flowchart showing a first TV-AF routine in the first embodiment. 7 is a flowchart illustrating a second TV-AF routine in the first embodiment. The figure for demonstrating the drive of the focus lens by 2nd TV-AF operation | movement. The figure for demonstrating the drive of the focus lens by 1st TV-AF operation | movement. 9 is a flowchart showing a scan range setting routine in Embodiment 2. 10 is a flowchart showing a first TV-AF routine in the third embodiment. 10 is a flowchart showing a second TV-AF routine in the third embodiment.

Explanation of symbols

2: Focus lens 8: Image sensor 9: Focus detection unit 22: Position detection unit 46: System controller 50: AF evaluation signal generator

Claims (6)

First focus detection means for outputting a first signal obtained by photoelectrically converting a plurality of optical images obtained by dividing a light beam from a photographing optical system including a focus lens;
Second focus detection means for generating a second signal indicating a contrast state of the subject image from a video signal obtained by photoelectrically converting an optical image formed by the photographing optical system;
Control means for determining a drive range of the focus lens based on the first signal and performing a scan drive for driving the focus lens by a predetermined amount within the drive range to obtain a focus position based on the second signal. When,
Position detecting means for detecting the position of the focus lens;
The control means changes the focus lens drive control sequence depending on whether the position detected by the position detection means is within the drive range or outside the drive range. machine.   When the detection position is within the driving range, the control unit drives the focus lens to a predetermined position within the driving range, and then performs the scan driving by reversing the driving direction. 2. The optical apparatus according to claim 1, wherein when the focus lens is out of the drive range, the scan drive is performed without inverting the drive direction after the focus lens is driven to the predetermined position. First focus detection means for outputting a first signal obtained by photoelectrically converting a plurality of optical images obtained by dividing a light beam from a photographing optical system including a focus lens;
Second focus detection means for generating a second signal indicating a contrast state of the optical image from a video signal obtained by photoelectrically converting the optical image formed by the photographing optical system;
Control means for obtaining a focus position based on the second signal by performing a scan drive for driving the focus lens by a predetermined amount;
The optical device according to claim 1, wherein the control unit changes a driving range in which the scan driving is performed according to an output level of the first signal.   The optical apparatus according to claim 3, wherein the control unit narrows the driving range when the output level of the first signal is higher than a predetermined value than when the output level is lower. First focus detection means for outputting a first signal obtained by photoelectrically converting a plurality of optical images obtained by dividing a light beam from a photographing optical system including a focus lens;
Second focus detection means for generating a second signal indicating a contrast state of the optical image from a video signal obtained by photoelectrically converting the optical image formed by the photographing optical system;
A driving range of the focus lens is determined based on the first signal, and a scan driving for driving the focus lens by a predetermined amount within the driving range is performed to determine a first focus position based on the second signal. Control means to obtain,
The control means obtains a second in-focus position based on the first signal during the scan driving and determines whether the second in-focus position is within the driving range. Optical equipment. The optical apparatus according to claim 5, wherein the control unit stops the scan driving when it is determined that the second in-focus position is out of the driving range.

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