Focus control device, lens device, and imaging device

Abstract

Provided are a focus control device, a lens device, and an imaging apparatus, all of which being capable of suppressing a change, in the angle of view, not intended by a user.　A beam splitter (16) divides an optical path of object light having passed through an imaging optical system (10) in which the focal distance is variable, into a first optical path toward a first imaging element (31) and a second optical path other than the first optical path. A second imaging element (27) receives the object light which has propagated through the second optical path and which has undergone pupil-division, and outputs a phase difference signal. A control unit (28) executes, in a first state where the focal distance of the imaging optical system (10) is equal to or more than a threshold value, automatic focus control for driving a focus lens (11) on the basis of the phase difference signal. In a second state where the focal distance of the imaging optical system (10) is less than the threshold value, the control unit (28) does not execute the automatic focus control, and sets the movable range (212) of the focus lens (11) in accordance with the phase difference signal acquired in the first state.

Description

[Technical Field]

[0001] The present invention relates to a focus control device, a lens device, and an imaging device. [Background technology]

[0002] When using a wide-angle focal length in an imaging device that uses an imaging lens with a variable focal length, highly accurate autofocusing is difficult due to the presence of subjects at different distances within the imaging range or the presence of high-frequency subjects. To address this issue, a known configuration disables autofocusing when using a wide-angle focal length. Because the depth of field is deep at wide-angle focal lengths, disabling autofocusing is unlikely to result in out-of-focus problems. However, when the focal length is changed from wide-angle to telephoto, autofocusing is automatically activated, resulting in a change in the angle of view (breathing) due to a change in the focus position.

[0003] Patent Document 1 describes that when, after manual focusing, focus adjustment is performed by autofocus for the purpose of assisting the focus adjustment by manual focusing, the movement amount of the focus lens by autofocus is limited to a predetermined amount or less. Patent Document 2 describes that a focus movement amount threshold used to determine whether or not to move the focus lens to a phase difference focusing position is changed depending on the zoom position.

[0004] Patent Document 3 describes that in a photographic lens equipped with a device that captures subject light using multiple focus state detection image sensors and detects the focus state based on the high-frequency components of the resulting luminance signal, the frequency of the luminance signal is converted by an electrical filter depending on the photographing state to detect the focus state. Patent Document 4 describes that in a system that performs AF using the optical path length difference method, a focus evaluation value generation unit that generates a focus evaluation value indicating the level of contrast from video signals obtained from two image sensors is provided with a high-pass filter that extracts high-frequency components from the video signal, the cutoff frequency of the high-pass filter is changed, and a focus evaluation value with characteristics depending on the setting state of the photographic lens is generated. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2003-241077 [Patent Document 2] Japanese Patent Publication No. 2008-203294 [Patent Document 3] Japanese Patent Publication No. 2003-287673 [Patent Document 4] Japanese Patent Publication No. 2005-156736 Summary of the Invention

[0006] One embodiment of the technique of the present disclosure provides a focus control device, a lens device, and an imaging device that can suppress a change in the angle of view unintentionally by a user. [Means for solving the problem]

[0007] The focus control device of the present invention includes a branching unit that branches the optical path of subject light that has passed through an imaging optical system with a variable focal length into a first optical path that proceeds to a first imaging element and a second optical path other than the first optical path; a second imaging element that receives the subject light that proceeds along the second optical path and is pupil-divided and outputs a phase difference signal; and a control unit that, in a first state in which the focal length is equal to or greater than a threshold, performs automatic focus control to drive a focus mechanism included in the imaging optical system based on the phase difference signal, and in a second state in which the focal length is less than the threshold, the control unit does not perform the automatic focus control and sets the movable range of the focus mechanism according to the phase difference signal obtained in the first state.

[0008] A lens device of the present invention includes the focus control device and the imaging optical system.

[0009] A lens device of the present invention includes the focus control device and the first image sensor. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a focus control device, a lens device, and an imaging device that can suppress changes in the angle of view that are not intended by the user. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing an example of an imaging device 100 including a lens device 1 to which a focus control device according to a first embodiment is applied. [Figure 2] 10 is a diagram showing an example of limiting the focus position on the wide-angle side by the control unit 28. FIG. [Figure 3] 10 is a flowchart showing an example of focus control processing by the control unit 28. [Figure 4] 10 is a flowchart showing an example of a first process performed by the control unit 28. [Figure 5] 10 is a diagram showing an example of setting of a first movable range in a first process by a control unit 28. FIG. [Figure 6] 10 is a flowchart showing an example of a second process performed by the control unit 28. [Figure 7] 10 is a diagram showing an example of setting of a second movable range in a second process by the control unit 28. FIG. [Figure 8] 10 is a flowchart showing an example of a third process performed by the control unit 28. [Figure 9] 10 is a diagram showing an example of setting of a third movable range in a third process by the control unit 28. FIG. [Figure 10] FIG. 10 is a schematic diagram showing an example of an imaging device 100B including a lens device 1 to which a focus control device according to a second embodiment is applied. [Figure 11] 10 is a flowchart showing a specific example 1 of focus control by the control unit 28 of the second embodiment. [Figure 12] 10A and 10B are diagrams illustrating an example of a reduction in high-frequency components of a phase difference signal by an LPF 101. [Figure 13] FIG. 10 is a diagram illustrating an example of low-pass intensity according to focal length. [Figure 14] 10 is a flowchart showing a specific example 2 of focus control by the control unit 28 of the second embodiment. [Figure 15] 10A and 10B are diagrams illustrating an example of a processing method of the LPF 101 according to the focal length. [Figure 16] 10 is a flowchart showing a specific example 3 of focus control by the control unit 28 of the second embodiment. [Figure 17] 10 is a flowchart showing a specific example 4 of focus control by the control unit 28 of the second embodiment. [Figure 18] FIG. 10 is a schematic diagram showing another example of the imaging device 100B according to the second embodiment. [Figure 19] 1 is a schematic diagram showing an example of an imaging device 100C equipped with an imaging device body 3 to which a focus control device of the present invention is applied. [Figure 20] 10 is a schematic diagram showing an example of an imaging device 100D that obtains a phase difference signal by a first imaging element 31. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] (Embodiment 1) <Image capture device 100 equipped with lens device 1 to which the focus control device of embodiment 1 is applied> 1 is a schematic diagram showing an example of an imaging device 100 including a lens device 1 to which the focus control device of Embodiment 1 is applied. The imaging device 100 is suitable for professional use, such as for broadcasting or film.

[0014] 1 includes a lens device 1 and an imaging device body 3 to which the lens device 1 is attached. The lens device 1 may be a lens device fixed to the imaging device body 3, or may be an interchangeable lens device that is detachable from the imaging device body 3.

[0015] The lens device 1 includes an imaging optical system 10 that includes multiple lenses and an aperture 14. In the example of FIG. 1, these multiple lenses include a focus lens 11, a zoom lens 12, a master lens group 15, and a motion compensation lens 17. The focus lens 11, the zoom lens 12, the aperture 14, the master lens group 15, and the motion compensation lens 17 are arranged in this order from the subject side. Note that FIG. 1 is for illustrative purposes only, and the lens configuration of the imaging optical system 10 is not limited to one that consists only of the lenses shown in the figure, and may also include multiple lenses that are not shown.

[0016] The focus lens 11 and the zoom lens 12 are supported so as to be movable parallel to the optical axis K1 of the imaging optical system 10. The focus lens 11 is a focus mechanism for changing the focus position of the imaging optical system 10. The zoom lens 12 is a zoom mechanism for changing the focal length of the imaging optical system 10. The image stabilization lens 17 is supported so as to be movable within a plane perpendicular to the optical axis K1 of the imaging optical system 10. The optical axis K1 of the imaging optical system 10 is a virtual light ray that represents a light beam passing through the imaging optical system 10, and is, for example, the axis of rotational symmetry of the focus lens 11, the zoom lens 12, the master lens group 15, and the image stabilization lens 17.

[0017] The lens device 1 further includes a beam splitter 16 including a reflecting surface 16a, an AF optical system 20, a second image sensor 27, a control unit 28, and a drive mechanism 29.

[0018] The drive mechanism 29 includes a drive mechanism for the focus lens 11 and a drive mechanism for the zoom lens 12. These drive mechanisms are configured with motors such as stepping motors. For example, under the control of the control unit 28, the drive mechanism 29 controls the focus position of the imaging optical system 10 by moving the focus lens 11 parallel to the optical axis K1. Also, under the control of the control unit 28, the drive mechanism 29 controls the focal length of the imaging optical system 10 by moving the zoom lens 12 parallel to the optical axis K1.

[0019] The beam splitter 16 is disposed on the optical axis K1 between the master lens group 15 and the image blur correction lens 17. The beam splitter 16 is an example of a branching section that branches the optical path of the subject light that has passed through the imaging optical system 10 into a first optical path that proceeds to the first image sensor 31 and a second optical path (an optical path that proceeds to the mirror 22) other than the first optical path.

[0020] The beam splitter 16 transmits a portion of the subject light (e.g., 80% of the subject light) that enters the imaging optical system 10 and passes through the aperture 14 and the master lens group 15, and reflects the remainder (e.g., 20% of the subject light) from the reflecting surface 16a in a direction intersecting the optical axis K1.

[0021] The position of the beam splitter 16 is not limited to that shown in Fig. 1, but may be any position behind the lens (e.g., focus lens 11) that is closest to the subject in the imaging optical system 10 on the optical axis K1 and in front of the image blur correction lens 17. A half mirror may also be used as the beam splitter 16. The half mirror can be formed, for example, by forming a thin metal film on glass.

[0022] The AF optical system 20 is an optical system that guides the subject light reflected by the beam splitter 16 to the second image sensor 27. Specifically, the AF optical system 20 includes a condenser lens 21, a mirror 22, and a condenser lens 26.

[0023] The condenser lens 21 is disposed on the optical path of the light reflected by the reflecting surface 16a of the beam splitter 16, and passes this light so that it is incident on the mirror 22. The mirror 22 is disposed on the optical path of the subject light that has passed through the condenser lens 21, and reflects this light so that it is incident on the condenser lens 26. The condenser lens 26 is disposed on the optical path of the subject light that has been reflected by the mirror 22, and passes this light so that it is incident on the second image sensor 27.

[0024] 1 is for illustrative purposes only, and the lens configuration of the AF optical system 20 is not limited to one consisting of only the lenses shown in the figure, but may also include multiple lenses not shown. Also, the AF optical system 20 may be configured to eliminate the mirror 22, and have the light reflected by the beam splitter 16 directly enter the second image sensor 27.

[0025] The second imaging element 27 is an example of a second imaging element that receives pupil-divided subject light that travels along the second optical path and outputs a phase difference signal. In this example, the second imaging element 27 is an image-plane phase difference imaging element having phase difference detection pixels that receive pupil-divided subject light that is incident from the condenser lens 26, i.e., subject light that travels along the second optical path. The second imaging element 27 outputs a pair of image signals that are shifted in one direction for one subject light image formed by the imaging optical system 10 as a phase difference signal from which phase difference information can be calculated.

[0026] For example, the second image sensor 27 has pairs of pixels arranged two-dimensionally across the entire light receiving surface, each pixel receiving one of a pair of light beams that have passed through two different portions aligned in one direction in the pupil region of the imaging optical system 10 and detecting a signal corresponding to the amount of received light, and each pixel receiving the other of the pair of light beams and detecting a signal corresponding to the amount of received light. Light coming from different directions is incident on each pixel of the second image sensor 27. By providing a light-shielding film within the pixels of the second image sensor 27 and receiving only one of the light beams coming from the different directions, phase difference information can be obtained.

[0027] The control unit 28 calculates phase difference information based on a pair of image signals output from the second imaging element 27, and calculates defocus information based on the calculated phase difference information. The defocus information is information indicating the current amount of defocus and the direction of defocus. The control unit 28 controls the focus position of the imaging optical system 10 by controlling the drive mechanism 29 to drive the focus lens 11 based on the calculated defocus information. The control unit 28 also controls the focal length of the imaging optical system 10 by controlling the drive mechanism 29 to drive the zoom lens 12 in response to, for example, a zoom operation by the user.

[0028] The control unit 28 is configured with a processor and a ROM (Read Only Memory) such as a RAM (Random Access Memory) and a flash memory. When a flash memory is used, the stored programs can be rewritten as needed. The control unit 28 realizes each function by executing programs, including a focus control program, stored in the built-in ROM.

[0029] The imaging device body 3 includes a first imaging element 31, such as a CMOS (Complementary Metal Oxide Semiconductor) type image sensor or a CCD (Charge Coupled Device) type image sensor, arranged on the optical axis K1 of the lens device 1, and an image processing unit 32 that processes an image signal obtained by capturing a subject light image using the first imaging element 31 to generate captured image data.

[0030] The captured image data generated by the image processing unit 32 is recorded, for example, on a recording medium (not shown) of the imaging device main body 3. The captured image data generated by the image processing unit 32 may be sequentially displayed as live images on a display device (not shown) of the imaging device main body 3.

[0031] <Limitation of focus position on wide-angle side by control unit 28> Fig. 2 is a diagram showing an example of limiting the focus position on the wide-angle side by the control unit 28. In Fig. 2, the horizontal axis represents the focal length of the imaging optical system 10, which changes depending on the position of the zoom lens 12, and corresponds to the angle of view in imaging using the lens device 1. The right side of the horizontal axis is the side where the focal length of the imaging optical system 10 is long, which corresponds to the telephoto side. The left side of the horizontal axis is the side where the focal length of the imaging optical system 10 is short, which corresponds to the wide-angle side.

[0032] The vertical axis represents the focus position of the imaging optical system 10, which changes depending on the position of the focus lens 11. The upper side of the vertical axis is the side farther from the imaging device 100, and the lower side of the vertical axis is the side closer to the imaging device 100.

[0033] The AF area 201 is an area where the focal length of the imaging optical system 10 is equal to or greater than a threshold value TH. The state where the focal length of the imaging optical system 10 is in the AF area 201 is an example of a first state of the present invention. The non-AF area 202 is an area where the focal length of the imaging optical system 10 is less than the threshold value TH. The state where the focal length of the imaging optical system 10 is in the non-AF area 202 is an example of a second state of the present invention. The threshold value TH is the shortest focal length at which a certain degree of accuracy is ensured in AF (autofocus) control, and is determined based on the characteristics of the imaging optical system 10, etc. The AF control is control that drives the focus lens 11 (focus mechanism) based on a phase difference signal obtained by the second image sensor 27.

[0034] Control unit 28 executes AF control in a first state in which the focal length of imaging optical system 10 is AF area 201. Control unit 28 also does not execute AF control in a second state in which the focal length of imaging optical system 10 is non-AF area 202, and sets movable range 212 of focus lens 11 in accordance with a phase difference signal obtained by second image sensor 27 in AF area 201 (i.e., the result of AF control).

[0035] The movable range 212 of the focus lens 11 is the movable range 212 of the focus lens 11 (i.e., the movable range of the focus position) that is allowed when, for example, a user of the imaging device 100 performs a manual focus operation to change the focus position of the imaging optical system 10.

[0036] Setting movable range 212 of focus lens 11 means that control unit 28 performs control to limit the drive range of focus lens 11 to within movable range 212. For example, in a configuration in which control unit 28 drives focus lens 11 in response to a manual focus operation from the user, control unit 28 performs control to ignore a manual focus operation that exceeds movable range 212 of focus lens 11, thereby limiting the drive range of focus lens 11 to movable range 212. Furthermore, in a configuration in which the manual focus operation is transmitted to drive mechanism 29 without passing through control unit 28, control unit 28 controls drive mechanism 29 to mechanically limit movable range 212 of focus lens 11, thereby limiting the drive range of focus lens 11 to movable range 212.

[0037] 2, focus position 211 is the focus position of imaging optical system 10 driven by AF control in AF area 201, and corresponds to the drive state of focus lens 11 driven by AF control in AF area 201. The drive state of focus lens 11 is, for example, the position of focus lens 11 in the direction of optical axis K1. Because focus position 211 is set by AF control in AF area 201, it is aligned with the subject with high accuracy.

[0038] The control unit 28 sets a movable range 212 in the non-AF area 202 based on the focus position 211. For example, the control unit 28 sets a range of focus positions centered on the focus position 211 as the movable range 212. However, the movable range 212 is not limited to a range centered on the focus position 211, and may be a range slightly shifted from the range centered on the focus position 211. For example, the movable range 212 may be a range from a position closer to the focus position 211 to a position farther from the focus position 211.

[0039] Furthermore, the control unit 28 sets a movable range 212 that becomes wider as the focal length of the imaging optical system 10 becomes shorter. As a result, in the non-AF area 202, the focus position of the imaging optical system 10 is limited to a range closer to the focus position 211 as the focal length of the imaging optical system 10 becomes closer to the threshold value TH.

[0040] In this way, control unit 28 executes AF control in the first state where the focal length of imaging optical system 10 is equal to or greater than threshold value TH. Furthermore, control unit 28 does not execute AF control in the second state where the focal length of imaging optical system 10 is less than threshold value TH, and sets the movable range of focus lens 11 in accordance with the phase difference signal obtained by second image sensor 27 in the first state (for example, based on focus position 211 set by AF control in the first state).

[0041] As a result, in the second state where the focal length of the imaging optical system 10 is less than the threshold value TH, the focus position of the imaging optical system 10 (the driving state of the focus lens 11) is maintained within the movable range 212 based on the phase difference signal obtained in the first state where the focal length of the imaging optical system 10 is equal to or greater than the threshold value TH. Therefore, it is possible to prevent the focus position of the imaging optical system 10 from suddenly changing due to AF control that is activated when the focal length of the imaging optical system 10 subsequently shifts from the non-AF area 202 to the AF area 201. This makes it possible to prevent an unintended change in the angle of view caused by lens breathing.

[0042] Furthermore, in the second state, the control unit 28 sets a wider movable range 212 as the focal length of the imaging optical system 10 becomes shorter. As a result, in the non-AF region 202, the focus position of the imaging optical system 10 is limited to a range closer to the focus position 211 as the focal length of the imaging optical system 10 becomes closer to the threshold value TH. This makes it possible to further suppress breathing when the focal length of the imaging optical system 10 transitions from the second state to the first state.

[0043] <Focus Control Processing by the Control Unit 28> Fig. 3 is a flowchart showing an example of focus control processing by the control unit 28. The control unit 28 executes the focus control processing shown in Fig. 3, for example, when the focal length of the imaging optical system 10 changes. The change in the focal length of the imaging optical system 10 is caused by, for example, a user operation (a zoom-out operation or a zoom-in operation), but may also be caused by automatic control in the imaging device 100.

[0044] First, the control unit 28 determines whether or not the focal length of the imaging optical system 10 has changed to the wide-angle side (step S31). A change in the focal length of the imaging optical system 10 to the wide-angle side means that the focal length of the imaging optical system 10 becomes shorter.

[0045] In step S31, if the focal length has changed to the wide-angle side (step S31: Yes), the control unit 28 executes a first process described later with reference to FIGS. 4 and 5 (step S32), and ends the series of processes.

[0046] In step S31, if there is no change in the focal length to the wide-angle side, i.e., if the focal length of the imaging optical system 10 has changed to the telephoto side (step S31: No), the control unit 28 determines whether the subject being imaged by the imaging device 100 is moving quickly (step S33).

[0047] For example, in the imaging device 100, subject detection is performed to detect a subject based on an image captured by at least one of the first imaging element 31 and the second imaging element 27. The subject detection may be performed by the control unit 28, or by a control unit of the imaging device 100 that is different from the control unit 28. The control unit 28 calculates the subject speed (movement speed of the subject) based on multiple subject detection results at different times, and makes the determination in step S33 by determining whether the subject speed exceeds a predetermined value. The subject speed may be, for example, two-level information, "fast" and "slow," or three or more levels.

[0048] In step S33, if the movement of the subject is not fast (step S33: No), the control unit 28 executes a second process described later with reference to FIGS. 6 and 7 (step S34), and ends the series of processes.

[0049] In step S33, if the movement of the subject is fast (step S33: Yes), control unit 28 executes a third process (step S35) which will be described later with reference to Figures 8 and 9, and ends the series of processes. Note that in step S33, if control unit 28 cannot determine whether the movement of the subject is fast (for example, if the subject cannot be detected), control unit 28 proceeds to, for example, step S35, that is, executes the third process in the same way as when the movement of the subject is fast.

[0050] <First Process by Control Unit 28> Fig. 4 is a flowchart showing an example of the first process by the control unit 28. In step S32 shown in Fig. 3, the control unit 28 executes, for example, the process shown in Fig. 4 as the first process. As described in Fig. 3, this first process is executed when the focal length of the imaging optical system 10 changes to the wide-angle side.

[0051] First, the control unit 28 clears the currently set movable range 212 (step S41). Next, the control unit 28 determines whether the focal length of the imaging optical system 10 is in the AF area 201, that is, whether it is in the first state (step S42).

[0052] In step S42, if the focal length of the imaging optical system 10 is within the AF region 201 (step S42: Yes), the control unit 28 executes AF control to drive the focus lens 11 based on the phase difference signal obtained by the second image sensor 27 (step S43), and ends the first processing sequence. That is, if the focal length of the imaging optical system 10 has changed to the wide-angle side but has not fallen below the threshold value TH, the AF control is executed.

[0053] In step S42, if the focal length of the imaging optical system 10 is not in the AF area 201, i.e., if the focal length of the imaging optical system 10 is in the non-AF area 202 (step S42: No), the control unit 28 calculates a first movable range based on the focus position 211 in the AF area 201 (step S44).

[0054] In step S44, for example, control unit 28 calculates a first movable range centered on the focus position in AF area 201. The focus position in AF area 201 is, for example, the focus position last set by AF control in the first state in the past. Note that if there is no history of AF area 201 or if a long time has passed since the last time AF area 201 was the AF area, control unit 28 may perform rough distance measurement, which will be described later, and calculate the first movable range based on the focus position derived by that distance measurement.

[0055] Next, the control unit 28 sets the movable range 212 of the focus lens 11 to the first movable range calculated in step S44 (step S45), and ends the first series of processing.

[0056] <Setting of First Movable Range in First Process by Control Unit 28> Fig. 5 is a diagram showing an example of setting of the first movable range in the first process by the control unit 28. In steps S44 and S45 shown in Fig. 4, the control unit 28 sets the first movable range centered on the focus position 211 set by the previous AF control in the AF area 201 as the movable range 212.

[0057] Furthermore, when the focal length of the imaging optical system 10 changes to the wide-angle side, the depth of field becomes deeper, so the effect on image quality due to a shift in focus position becomes smaller, and the need to change the focus position becomes less. For this reason, the control unit 28 sets the first movable range 212 to be narrower than when the focal length of the imaging optical system 10 changes to the telephoto side (see, for example, FIGS. 7 and 9). This limits the focus position of the imaging optical system 10 to a range closer to the focus position 211 in the non-AF area 202, making it possible to further suppress breathing when transitioning from the second state to the first state.

[0058] <Second Process by Control Unit 28> Fig. 6 is a flowchart showing an example of the second process by the control unit 28. In step S34 shown in Fig. 3, the control unit 28 executes, for example, the process shown in Fig. 6 as the second process. As described in Fig. 3, this second process is executed when the focal length of the imaging optical system 10 changes to the telephoto side and the movement of the subject is not fast.

[0059] First, the control unit 28 clears the currently set movable range 212 (step S61). Next, the control unit 28 determines whether the focal length of the imaging optical system 10 is within the AF area 201, i.e., whether the focal length of the imaging optical system 10 is equal to or greater than the threshold value TH (step S62).

[0060] In step S62, if the focal length of the imaging optical system 10 is within the AF area 201 (step S62: Yes), the control unit 28 performs AF control to drive the focus lens 11 based on the phase difference signal obtained by the second imaging element 27 (step S63), and ends the second series of processing.

[0061] In step S62, if the focal length of the imaging optical system 10 is in the non-AF region 202 (step S62: No), the focal length of the imaging optical system 10 has changed to the telephoto side within a range less than the threshold value TH. In this case, the control unit 28 performs distance measurement (e.g., calculation of defocus information) based on the phase difference signal obtained by the second image sensor 27 (step S64). This distance measurement is performed in the second state in which the focal length of the imaging optical system 10 is in the non-AF region 202, and therefore is a rough distance measurement with low accuracy.

[0062] Next, control unit 28 calculates a second movable range based on the rough distance measurement in step S64 (step S65). For example, control unit 28 calculates the second movable range centered on the focus position derived based on the rough distance measurement in step S64. Next, control unit 28 sets movable range 212 of focus lens 11 to the second movable range calculated in step S65 (step S66), and ends the second series of processes.

[0063] In the coarse distance measurement in step S64, control unit 28 may perform AF control to drive focus lens 11 based on the distance measurement result, in addition to distance measurement based on the phase difference signal obtained by second image sensor 27. The AF control in this case is AF control in the second state in which the focal length of imaging optical system 10 is in non-AF area 202, and therefore is coarse AF control with low accuracy.

[0064] <Setting of the second movable range in the second process by the control unit 28> 7 is a diagram showing an example of setting the second movable range in the second process by the control unit 28. In steps S65 and S66 shown in FIG. 6, the control unit 28 sets the second movable range centered on the focus position based on the rough distance measurement as the movable range 212.

[0065] Furthermore, when the focal length of the imaging optical system 10 is changed to the telephoto side, the depth of field becomes shallower, which increases the impact on image quality due to a shift in focus position and the need to change the focus position. For this reason, the control unit 28 sets the second movable range 212 to be wider than when the focal length of the imaging optical system 10 is changed to the wide-angle side. This makes it possible to prevent a situation in which focusing becomes impossible in the non-AF area 202 due to limitations on changing the focus position, despite the large impact on image quality due to a shift in focus position.

[0066] However, if the subject is not moving quickly, the focus position is unlikely to shift in the first place, and therefore there is less need to change the focus position. For this reason, the control unit 28 sets the second movable range 212 to a narrower range than when the subject is moving quickly or when it cannot be determined whether the subject is moving quickly (see, for example, FIG. 9). This limits the focus position of the imaging optical system 10 to a range closer to the focus position 211 in the non-AF area 202, thereby making it possible to further suppress breathing when transitioning from the second state to the first state.

[0067] <Third Process by Control Unit 28> Fig. 8 is a flowchart showing an example of the third process by the control unit 28. In step S35 shown in Fig. 3, the control unit 28 executes, for example, the process shown in Fig. 8 as the third process. As described in Fig. 3, this third process is executed when there is a change in the focal length of the imaging optical system 10 to the telephoto side and the movement of the subject is fast, or when it cannot be determined whether the movement of the subject is fast or not.

[0068] Steps S81 to S86 shown in Fig. 8 are the same as steps S61 to S66 shown in Fig. 6. However, in step S85, control unit 28 calculates a third movable range based on the rough distance measurement in step S84. For example, control unit 28 calculates a third movable range centered on the focus position derived based on the rough distance measurement in step S84. Furthermore, in step S86, control unit 28 sets movable range 212 of focus lens 11 to the third movable range calculated in step S85. This third movable range is wider than the second movable range in the second process.

[0069] <Setting of the Third Movable Range in the Third Process by the Control Unit 28> 9 is a diagram showing an example of setting the third movable range in the third process by the control unit 28. In steps S85 and S86 shown in FIG. 8, the control unit 28 sets the third movable range centered on the focus position based on the rough distance measurement as the movable range 212.

[0070] When the subject is moving quickly, or when it is not possible to determine whether the subject is moving quickly, the focus position is likely to shift, increasing the need to change the focus position. For this reason, control unit 28 sets a third movable range 212 that is wider than when the subject is not moving quickly (see, for example, FIG. 8). This makes it possible to prevent a situation in which focus cannot be achieved in non-AF area 202 due to limitations on changing the focus position, even though the effect on image quality due to shifting of the focus position is significant and shifting of the focus position is likely to occur.

[0071] 6 to 9, in the second state, control unit 28 sets movable range 212 with a width corresponding to the subject speed based on pixel data obtained by at least one of first image sensor 31 and second image sensor 27. Specifically, control unit 28 sets a wider movable range 212 in non-AF area 202 as the subject speed increases (the subject moves faster). As a result, when the subject is not moving quickly (see FIGS. 6 and 7), a relatively narrow movable range 212 is set to further suppress breathing when transitioning from the second state to the first state, and when the subject is moving quickly (see FIGS. 8 and 9), a relatively wide movable range 212 is set to suppress situations in which focusing becomes impossible.

[0072] Furthermore, when the focal length of the imaging optical system 10 changes within a range less than the threshold value TH in the second state (see FIGS. 6 to 9), the control unit 28 performs the above-described rough distance measurement, for example, to set the movable range 212 in the second state according to the phase difference signal obtained by the second image sensor 27. As a result, even when the focal length of the imaging optical system 10 changes within a range less than the threshold value TH and the focus position in the AF area 201 cannot be referenced, the movable range 212 can be set based on a focus position that roughly matches the subject, and breathing can be suppressed when transitioning from the second state to the first state.

[0073] Furthermore, at this time, the control unit 28 sets a wider movable range 212 than when transitioning from the first state to the second state (see, for example, FIGS. 4 and 5). This makes it possible to prevent a situation in which focusing becomes impossible due to limitations on changing the focus position, even if the focus position determined by the above-mentioned rough distance measurement is slightly deviated from the subject.

[0074] (Embodiment 2) The second embodiment will be described in terms of the differences from the first embodiment.

[0075] <Image capture device 100B equipped with lens device 1 employing the focus control device of the present invention> Fig. 10 is a schematic diagram showing an example of an imaging device 100B including a lens device 1 to which the focus control device of embodiment 2 is applied. In Fig. 10, parts that are the same as those shown in Fig. 1 are given the same reference numerals and descriptions thereof will be omitted.

[0076] 1, the imaging device 100B further includes an LPF (Low Pass Filter) 101. The LPF 101 performs processing on the phase difference signal output from the second imaging element 27 to the control unit 28 to attenuate only high-frequency components higher than a specific cutoff frequency. The LPF 101 is configured so that the degree of attenuation of high-frequency components can be varied under control of the second imaging element 27.

[0077] For example, in a configuration in which the phase difference signal output by the second imaging element 27 is an analog signal and the phase difference signal is converted from an analog signal to a digital signal in the control unit 28, the LPF 101 is configured by an analog circuit. In this case, the LPF 101 may be an analog circuit incorporated in the second imaging element 27.

[0078] Furthermore, in a configuration in which the phase difference signal output from second imaging element 27 is a digital signal, LPF 101 is configured by a digital circuit (digital filter). In this case, LPF 101 may be a digital circuit incorporated in control unit 28, or may be realized in software by control unit 28 executing a program.

[0079] <Specific Example 1 of Focus Control by Control Unit 28 of Second Embodiment> 11 is a flowchart showing a specific example 1 of focus control by the control unit 28 according to the embodiment 2. In this example, a case will be described in which the LPF 101 is provided as a separate component from the control unit 28.

[0080] First, the control unit 28 acquires the focal length of the current imaging optical system 10 and sets the low-pass intensity (degree of reduction of high-frequency components) corresponding to the acquired focal length in the LPF 101 (step S111). The low-pass intensity corresponding to the focal length will be described later in FIG. 13. Next, the control unit 28 acquires the phase difference signal output from the second imaging element 27 and processed by the LPF 101 (step S112).

[0081] Next, the control unit 28 calculates defocus information based on the phase difference signal acquired in step S112 (step S113). Next, the control unit 28 performs control to drive the focus lens 11 based on the defocus information calculated in step S113 (step S114), and ends a series of processes.

[0082] <Reduction of High-Frequency Components of Phase Difference Signal by LPF101> FIG. 12 is a diagram showing an example of the reduction of high-frequency components of the phase difference signal by the LPF 101. Here, first, the correlation operation by the control unit 28 based on the phase difference signal will be described. The control unit 28 performs a correlation operation between a first signal group included in one of the pair of image signals output as the phase difference signal from the second imaging element 27 and a first signal group included in the other image signal, and based on the result of the correlation operation, detects the phase difference, which is the amount of deviation in the pupil division direction between the first signal group and the second signal group.

[0083] Specifically, this correlation operation is a process of calculating the data of the first signal group as A[1]…A[k], the data of the second signal group as B[1]…B[k], and calculating the correlation value of the two data when these two data are shifted by “d” in the pupil division direction. The correlation value can be obtained by the area S[d] surrounded by the two data waveforms obtained by the following formula (1). The smaller the correlation value, the higher the degree of coincidence of the two data.

[0084]

Equation

[0085] A graph showing the change in correlation value when the horizontal axis is the shift amount d between two pieces of data and the vertical axis is the area S[d], which is the correlation value between the two pieces of data, is called a correlation curve, and this correlation curve is the result of the correlation calculation. Since this correlation curve contains at least one valley (a portion where the correlation value is minimal), the shift amount d corresponding to one of the valleys contained in the correlation curve is detected as the phase difference in the pupil division direction between the first signal group and the second signal group.

[0086] Control unit 28 controls the position of focus lens 11 by causing drive mechanism 29 to drive focus lens 11 according to a drive amount corresponding to the detected phase difference. Information indicating the correspondence between the phase difference and the drive amount of focus lens 11 is obtained in advance, such as during manufacture of lens device 1, and is stored in a memory accessible to control unit 28. Control unit 28 reads out the drive amount corresponding to the phase difference from the memory and transmits the read drive amount to drive mechanism 29. Drive mechanism 29 moves focus lens 11 by the transmitted drive amount.

[0087] 12 is a correlation curve obtained from the phase difference signal output from the second image sensor 27 when the focal length of the imaging optical system 10 is relatively short and it is assumed that the LPF 101 is not provided. When the focal length of the imaging optical system 10 is relatively short, the angle of view becomes wide, objects at different distances are mixed within the imaging range, and the objects have high frequencies, so the correlation curve 121 includes high-frequency components. This makes it difficult for the control unit 28 to accurately calculate defocus information.

[0088] 12 is a correlation curve obtained from the phase difference signal output from the second image sensor 27 when the imaging device 100 is provided with the LPF 101 and the focal length of the imaging optical system 10 is relatively short as shown in FIG. 10. By reducing the high-frequency components of the phase difference signal with the LPF 101, the correlation curve 122 also has reduced high-frequency components. This allows the control unit 28 to accurately calculate defocus information.

[0089] <Low-pass strength according to focal length> 13 is a diagram showing an example of low-pass intensity according to focal length. In FIG. 13, the horizontal axis represents the focal length of the imaging optical system 10, and the vertical axis represents the low-pass intensity (degree of reduction in high-frequency components) of the LPF 101. Correspondence information 130 indicates the correspondence relationship between the focal length of the imaging optical system 10 and the low-pass intensity of the LPF 101.

[0090] 13, in the correspondence information 130, the shorter the focal length of the imaging optical system 10, the lower the low-pass intensity of the corresponding LPF 101. Note that in the example of the correspondence information 130 shown in Fig. 13, among the focal lengths of the imaging optical system 10, a constant high low-pass intensity is associated with the shortest certain range, a constant low low-pass intensity is associated with the longest certain range, and in the intermediate range, the low-pass intensity decreases linearly as the focal length increases.

[0091] Correspondence information 130 is stored in a memory accessible by control unit 28. Correspondence information 130 may be table information that associates the focal length of imaging optical system 10 with the low-pass intensity of LPF 101, or may be a function that can derive the low-pass intensity of LPF 101 from the focal length of imaging optical system 10.

[0092] For example, in step S111 shown in FIG. 11, the control unit 28 derives the low-pass intensity corresponding to the current focal length of the imaging optical system 10 from the correspondence information 130, and sets the derived low-pass intensity in the LPF 101.

[0093] 13 is an example, and various modifications are possible. For example, in the correspondence information 130, the low-pass intensity may linearly decrease as the focal length decreases across the entire range of focal lengths of the imaging optical system 10. Alternatively, in the correspondence information 130, the low-pass intensity of the LPF 101 may nonlinearly decrease as the focal length of the imaging optical system 10 decreases. Alternatively, in the correspondence information 130, a first low-pass intensity may be associated with a focal length less than a threshold, and a second low-pass intensity lower than the first low-pass intensity may be associated with a focal length equal to or greater than the threshold.

[0094] Furthermore, when the focal length of the imaging optical system 10 is equal to or greater than a threshold, the low-pass intensity may be set to 0, i.e., the processing by the LPF 101 may not be performed. For example, in the example of correspondence information 130 shown in Fig. 13, a certain range of the longest focal lengths of the imaging optical system 10 may be associated with low-pass intensity = 0. That is, the control unit 28 may cause the processing by the LPF 101 to be performed in the AF control when the focal length of the imaging optical system 10 is less than the threshold, and may not cause the processing by the LPF 101 to be performed in the AF control when the focal length of the imaging optical system 10 is equal to or greater than the threshold.

[0095] In this way, the image capture device 100B drives the focus lens 11 in accordance with phase difference information obtained by processing the LPF 101 on a phase difference signal based on branched and pupil-divided subject light, thereby enabling highly accurate focus control even when the focal length of the image capture optical system 10 is on the wide-angle side. This makes it possible to suppress unintended changes in the angle of view caused by lens breathing when the focal length of the image capture optical system 10 changes from the wide-angle side to the telephoto side.

[0096] Furthermore, the degree of reduction of high frequency components in the processing of the LPF 101 can be set according to the degree of difficulty in focus control by setting the degree of reduction of high frequency components according to the focal length of the imaging optical system 10. Specifically, by increasing the degree of reduction of high frequency components as the focal length of the imaging optical system 10 becomes shorter, it is possible to suppress a decrease in the accuracy of focus control caused by a wide angle of view, and to suppress the effect of the processing of the LPF 101 on focus control when the angle of view is narrow.

[0097] <Specific Example 2 of Focus Control by Control Unit 28 of Second Embodiment> 14 is a flowchart showing a second specific example of focus control by the control unit 28 according to the second embodiment. In this example, too, a case will be described in which the LPF 101 is provided as a separate component from the control unit 28. In this example, the low-pass filter processing method of the LPF 101 is configured to be variable under control of the second image sensor 27. By changing the processing method of the LPF 101, the degree to which the high-frequency components of the phase difference signal in the LPF 101 are reduced changes.

[0098] First, the control unit 28 acquires the current focal length of the imaging optical system 10, and sets a processing method (degree of reduction of high-frequency components) corresponding to the acquired focal length in the LPF 101 (step S141). The processing method of the LPF 101 according to the focal length will be described later with reference to Fig. 15. Steps S142 to S145 shown in Fig. 14 are the same as steps S112 to S115 shown in Fig. 11.

[0099] <LPF101 processing method according to focal length> Fig. 15 is a diagram showing an example of the processing method of the LPF 101 according to the focal length. In Fig. 15, the horizontal axis indicates the focal length of the imaging optical system 10, and the vertical axis indicates the processing method of the LPF 101. The processing method higher on the vertical axis indicates the degree of reduction in high frequency components. Correspondence information 150 indicates the correspondence relationship between the focal length of the imaging optical system 10 and the processing method of the LPF 101.

[0100] 15, in the correspondence information 150, the shorter the focal length of the imaging optical system 10, the greater the degree of reduction in high frequency components of the processing method of the corresponding LPF 101. Specifically, a focal length of less than 100 [mm] is associated with "horizontal 4-mixed," a focal length of 100 [mm] or more but less than 500 [mm] is associated with "horizontal 2-mixed," and a focal length of 500 [mm] or more is associated with "no mixing."

[0101] "Horizontal 4 Blend" is a blending process that blends four horizontally adjacent pixels in the target image (averaging pixel values) to form one pixel. "Horizontal 4 Blend" reduces the number of pixels in the target image to 1 / 4. "Horizontal 2 Blend" is a blending process that blends two horizontally adjacent pixels in the target image to form one pixel. "Horizontal 2 Blend" reduces the number of pixels in the target image to 1 / 2. "No Blend" is a process that does not blend pixels.

[0102] The pixel blending method may be a method of calculating a simple average of pixel values ​​or a method of calculating a weighted average of pixel values, where the weighting coefficients used in the weighted average may be determined based on a Gaussian function.

[0103] Correspondence information 150 is stored in a memory accessible by the control unit 28. The correspondence information 150 may be table information that associates the focal length of the imaging optical system 10 with the LPF type of the LPF 101, or may be a function or the like that can derive the LPF type of the LPF 101 from the focal length of the imaging optical system 10.

[0104] For example, in step S141 shown in FIG. 14, the control unit 28 derives the LPF method corresponding to the current focal length of the imaging optical system 10 from the correspondence information 150, and sets the derived LPF method in the LPF 101.

[0105] 15 is an example, and various modifications are possible. For example, the processing method of the switchable LPF 101 may include a mixing process of mixing three horizontally adjacent pixels in the target image to form one pixel, or a mixing process of mixing five or more horizontally adjacent pixels in the target image to form one pixel.

[0106] Also, as in the example of Figure 15, the control unit 28 may execute processing of LPF101 in AF control when the focal length of the imaging optical system 10 is less than a threshold value (e.g., 500 [mm]), and may not execute processing of LPF101 in AF control when the focal length of the imaging optical system 10 is equal to or greater than the threshold value.

[0107] As shown in FIGS. 14 and 15, the image pickup device 100B may set the degree of reduction of high frequency components in the LPF 101 by switching the processing method of the LPF 101.

[0108] <Specific Example 3 of Focus Control by Control Unit 28 of Second Embodiment> 16 is a flowchart showing a third specific example of focus control by the control unit 28 of the second embodiment. In this example, too, a case will be described in which the LPF 101 is provided as a separate component from the control unit 28. In this example, the control unit 28 performs AF control using pixels included in the detection area of ​​the second image sensor 27, and the detection area of ​​the second image sensor 27 is variable. The detection area may be set by a user operation, or may be set automatically based on the result of the subject detection described above.

[0109] First, the control unit 28 acquires the current focal length of the imaging optical system 10 and the size of the current detection area, and sets a low-pass intensity (the degree of reduction of high-frequency components) according to the acquired focal length and size of the detection area in the LPF 101 (step S161). Steps S162 to S165 shown in Fig. 16 are the same as steps S112 to S115 shown in Fig. 11.

[0110] For example, a memory accessible to control unit 28 stores correspondence information that associates low-pass intensity with each combination of focal length of imaging optical system 10 and the size of the detection area of ​​second imaging element 27. This correspondence information may be table information that associates combinations of focal length and detection area size with low-pass intensity, or may be a function that can derive low-pass intensity from combinations of focal length and detection area size. In this correspondence information, if the focal length of imaging optical system 10 is the same, a larger detection area of ​​second imaging element 27 is associated with a higher low-pass intensity (degree of reduction).

[0111] For example, in step S161 shown in FIG. 16, the control unit 28 derives the low-pass intensity corresponding to the current focal length of the imaging optical system 10 from the correspondence information, and sets the derived low-pass intensity in the LPF 101.

[0112] 16, the control unit 28 may set the degree of reduction of high frequency components in the LPF 101 by switching the processing method of the LPF 101, as described in Fig. 14 and Fig. 15. In this case, the correspondence information is such that the processing method of the LPF 101 is associated with each combination of the focal length of the imaging optical system 10 and the size of the detection area of ​​the second imaging element 27.

[0113] In this way, the image capture device 100B performs AF control using pixel data obtained from pixels included in the variable detection area of ​​the second image sensor 27, and the larger the detection area, the greater the degree of reduction in high-frequency components of the phase difference signal. As a result, the larger the detection area of ​​the second image sensor 27, that is, the more subjects at different distances are present in the detection area or the more likely the subjects in the detection area are to have high frequencies, the greater the degree of reduction in high-frequency components, making it possible to suppress a decrease in the accuracy of focus control.

[0114] <Specific Example 4 of Focus Control by Control Unit 28 of Second Embodiment> 17 is a flowchart showing a fourth specific example of focus control by the control unit 28 according to the second embodiment. In this example, the LPF 101 is provided as a separate component from the control unit 28. In this example, the control unit 28 acquires a subject type based on the above-described subject detection. The subject type is a type of subject, such as a blue sky, a person, or a leopard.

[0115] First, the control unit 28 acquires the current focal length of the imaging optical system 10 and the current object type, and sets a low-pass intensity (degree of reduction of high-frequency components) according to the acquired focal length and object type in the LPF 101 (step S171). Steps S172 to S175 shown in Fig. 17 are the same as steps S112 to S115 shown in Fig. 11.

[0116] For example, memory accessible to control unit 28 stores correspondence information associating low-pass intensity with each combination of focal length of imaging optical system 10 and subject type of second image sensor 27. This correspondence information may be table information associating low-pass intensity with combinations of focal length and subject type, or may be a function or the like that can derive low-pass intensity from combinations of focal length and subject type. In this correspondence information, for example, a subject type such as a blue sky with few high-frequency components is associated with a relatively low low-pass intensity, and a subject type such as a leopard with a spotted pattern of repeating high-frequency components is associated with a relatively high low-pass intensity.

[0117] For example, in step S171 shown in FIG. 17, the control unit 28 derives the low-pass intensity corresponding to the current focal length of the imaging optical system 10 from the correspondence information, and sets the derived low-pass intensity in the LPF 101.

[0118] 17, the control unit 28 may set the degree of reduction of high frequency components in the LPF 101 by switching the processing method of the LPF 101, as described in Fig. 14 and Fig. 15. In this case, the correspondence information is such that the processing method of the LPF 101 is associated with each combination of the focal length of the imaging optical system 10 and the type of subject of the second imaging element 27.

[0119] In this way, the imaging device 100B sets the degree of reduction of the high-frequency components of the phase difference signal based on the result of determining the type of subject based on pixel data obtained by at least one of the first imaging element 31 and the second imaging element 27. This sets the degree of reduction of the high-frequency components of the phase difference signal in accordance with the degree of the high-frequency components according to the type of subject, making it possible to suppress a decrease in the accuracy of focus control.

[0120] The detection area of ​​the second image sensor 27 may be divided into multiple areas, and the LPF 101 may be configured to reduce high-frequency components of the phase difference signal for each area to different degrees. The object detection may also be performed for each area included in the detection area of ​​the second image sensor 27.

[0121] 17 for each area included in the detection area of ​​the second image sensor 27. That is, the control unit 28 sets each area included in the detection area of ​​the second image sensor 27 as a target area, acquires the current focal length of the imaging optical system 10 and the subject type of the target area, and sets a low-pass intensity according to the acquired focal length and subject type in a portion of the LPF 101 that corresponds to the target area. However, the control unit 28 may perform this process for only a portion of the areas included in the detection area of ​​the second image sensor 27 as the target area.

[0122] In this way, the control unit 28 may set the degree of reduction of the high-frequency components of the phase difference signal according to the determination result of the subject type in accordance with a plurality of areas included in the detection area of ​​the second imaging element 27. In this way, when the detection area of ​​the second imaging element 27 includes a plurality of subjects of different types, it is possible to set the degree of reduction of the high-frequency components of the phase difference signal appropriately for each subject.

[0123] 16 and 17 may be combined. For example, the control unit 28 may set the degree of reduction of the high frequency components of the phase difference signal based on a combination of the focal length of the imaging optical system 10, the size of the detection area of ​​the second imaging element 27, and the subject type based on the subject detection.

[0124] <Another Example of Imaging Device 100B According to Second Embodiment> Fig. 18 is a schematic diagram showing another example of the image pickup device 100B according to the second embodiment. In Fig. 18, the same parts as those shown in Fig. 10 are denoted by the same reference numerals, and the description thereof will be omitted. As shown in Fig. 18, the image pickup device 100B may include an optical LPF 181 instead of the LPF 101.

[0125] The optical LPF 181 is an optical filter provided in the AF optical system 20, and is, for example, an optical low pass filter that separates incident light rays into ordinary rays and extraordinary rays and blurs them. The degree to which high-frequency components are reduced in the optical LPF 181 can be changed, for example, by providing multiple optical low pass filters that reduce high-frequency components to different degrees and switching between the optical low pass filters that are located on the optical path of the AF optical system 20.

[0126] The control unit 28 sets the degree of reduction of high frequency components in the optical LPF 181 based on the focal length, etc. of the imaging optical system 10, in the same way as setting the degree of reduction of high frequency components in the LPF 101 based on the focal length, etc. of the imaging optical system 10. As in the example of Fig. 18 , the target of the process of reducing high frequency components of the phase difference signal is not limited to the phase difference signal, but may be subject light for obtaining the phase difference signal.

[0127] Furthermore, in the above embodiment, a configuration has been described in which processing for reducing high-frequency components of the phase difference signal is performed using the LPF 101 or the optical LPF 181, but a band-pass filter that reduces frequency components with lower and upper limits may be used instead of the LPF 101 or the optical LPF 181. Even in this case, the same effect can be obtained by setting relatively low frequency components of the main frequency components included in the phase difference signal as the transmission frequency of the band-pass filter and relatively high frequency components as the attenuation frequency of the band-pass filter.

[0128] In this way, the image pickup apparatus 100B may be any apparatus that performs processing to reduce specific frequency components of a phase difference signal based on subject light that has been branched and pupil-divided.

[0129] (Embodiment 3) As the third embodiment, a configuration combining the first and second embodiments will be described. The configuration of the imaging device of the third embodiment is similar to that of the imaging device 100B of the second embodiment shown in, for example, Fig. 10 or 18. The control unit 28 of the third embodiment executes the control of the first embodiment described above, and may also execute the ranging of the second embodiment as the coarse ranging included in the control of the first embodiment described above.

[0130] As an example, the control unit 28 executes steps S111 to S114 shown in Fig. 11 as rough distance measurement in step S64 in the second process shown in Fig. 6. This improves the accuracy of distance measurement, and therefore, even in the second state where the focal length of the imaging optical system 10 is less than the threshold value TH, it is possible to set the movable range 212 based on a highly accurate distance measurement result (focus position) and suppress breathing when transitioning from the second state to the first state.

[0131] Although the ranging in step S64 in the second processing shown in Fig. 6 has been described, the ranging in embodiment 2 may also be performed as the ranging in step S74 in the second processing shown in Fig. 7. Furthermore, although the processing shown in Fig. 11 has been described as ranging in embodiment 2, various other ranging methods than those in embodiment 2 may also be used.

[0132] (Variation 1) In each of the above embodiments, an image plane phase difference system configuration in which pupil division is performed by providing a light-shielding film on some of the pixels of the second image sensor 27 has been described, but the configuration by which the second image sensor 27 obtains a phase difference signal is not limited to the image plane phase difference system. For example, a separator lens system configuration in which a light-shielding film is not provided on the pixels of the second image sensor 27 and multiple lenses (separator lenses) that perform pupil division are provided between the condenser lens 26 and the second image sensor 27 may be used. Even in the separator lens system configuration, light rays are incident on the pixels of the second image sensor 27 at different angles, and a pair of image signals with different phases can be obtained as phase difference signals, as in the image plane phase difference system configuration.

[0133] (Variation 2) In each of the above embodiments, the control unit 28 may be able to switch between executing and not executing AF control. This switching may be performed in response to a user operation, or may be performed automatically based on various information obtainable by the control unit 28. When executing AF control, the control unit 28 performs control to set the degree of reduction of a specific frequency of the phase difference signal in accordance with the focal length of the imaging optical system 10.

[0134] (Variation 3) Although the focus control device of the present invention is applied to the lens device 1 in the above description, the focus control device of the present invention can also be applied to the imaging device body 3.

[0135] 19 is a schematic diagram showing an example of an imaging device 100C including an imaging device body 3 to which a focus control device of the present invention is applied. In the example of Fig. 19, the focus control device of the first embodiment is applied to the imaging device body 3, but the focus control device of the second embodiment may also be applied to the imaging device body 3.

[0136] 19 has the same configuration as the imaging device 100 shown in Fig. 1, except that the beam splitter 16, the AF optical system 20, the second imaging element 27, and the control unit 28 are provided in the imaging device body 3. In this case, the beam splitter 16 is provided on the subject side of the first imaging element 31.

[0137] Furthermore, if the lens device 1 is an interchangeable type, the control unit 28 may acquire information about the focal length of the lens device 1 attached to the imaging device body 3 from the lens device 1, and set the movable range of the focus lens 11 based on the focal length of the imaging optical system 10. Furthermore, if the lens device 1 is an interchangeable type, the control unit 28 acquires information about the focal length of the lens device 1 and controls the drive mechanism 29 via a communication interface of the connection unit (lens mount) between the lens device 1 and the imaging device body 3.

[0138] (Variation 4) Although the configuration has been described in which the subject light is split and a phase difference signal is obtained by the second imaging element 27 provided separately from the first imaging element 31, the configuration is not limited to this, and the phase difference signal may also be obtained by the first imaging element 31.

[0139] 20 is a schematic diagram showing an example of an imaging device 100D that obtains a phase difference signal by a first imaging element 31. In the example of FIG. 20, the focus control device of the first embodiment is applied to the imaging device body 3, but the focus control device of the second embodiment may also be applied to the imaging device body 3.

[0140] 20 is the same as the configuration of the image pickup device 100C shown in FIG. 19, except that the beam splitter 16, the AF optical system 20, and the second image pickup element 27 are omitted. In this case, an image plane phase difference type configuration is adopted using the first image pickup element 31, and the first image pickup element 31 outputs a phase difference signal separately from the pixel data for recording. The control unit 28 performs the above-mentioned controls based on the phase difference signal output from the first image pickup element 31.

[0141] As described above, the present specification discloses the following:

[0142] (1) a branching unit that branches an optical path of subject light that has passed through an imaging optical system with a variable focal length into a first optical path that proceeds to a first imaging element and a second optical path other than the first optical path; a second image sensor that receives the subject light that has traveled through the second optical path and been pupil-divided and outputs a phase difference signal; a control unit that performs automatic focus control to drive a focus mechanism included in the imaging optical system based on the phase difference signal in a first state in which the focal length is equal to or greater than a threshold value; Equipped with The control unit In a second state in which the focal length is less than the threshold value, the automatic focus control is not executed, and a movable range of the focus mechanism is set in accordance with the phase difference signal obtained in the first state. Focus control device.

[0143] (2) The focus control device according to (1), The control unit In the second state, the movable range is set based on a driving state of the focus mechanism driven in accordance with the phase difference signal obtained in the first state. Focus control device.

[0144] (3) The focus control device according to (2), The control unit When the first state is shifted to the second state, the automatic focus control is stopped; setting the movable range based on the driving state of the focus mechanism; Focus control device.

[0145] (4) A focus control device according to any one of (1) to (3), The control unit In the second state, the movable range is set to a width corresponding to the focal length. Focus control device.

[0146] (5) The focus control device according to (4), The control unit In the second state, the shorter the focal length, the wider the movable range is set. Focus control device.

[0147] (6) A focus control device according to any one of (1) to (5), The control unit In the second state, the movable range is set to a width corresponding to a subject speed based on pixel data obtained by at least one of the first imaging element and the second imaging element. Focus control device.

[0148] (7) (6) The focus control device according to the present invention, The control unit In the second state, the greater the object speed, the wider the movable range is set. Focus control device.

[0149] (8) A focus control device according to any one of (1) to (7), The control unit When the focal length changes within a range less than the threshold value in the second state, the movable range is set in accordance with the phase difference signal obtained in the second state. Focus control device.

[0150] (9) (8) The focus control device according to the present invention, The control unit When the focal length changes within a range less than the threshold value in the second state, the movable range is set to be wider than when transitioning from the first state to the second state. Focus control device.

[0151] (10) The focus control device according to (8) or (9), The control unit In the second state, when the focal length changes within a range less than the threshold value, performing low-pass filtering on pixel data obtained by the second imaging element in the second state; setting the movable range in accordance with the phase difference signal obtained by the processing; Focus control device.

[0152] (12) The focus control device according to (10), The control unit The degree of reduction of high frequency components in the processing is set according to the focal length. Focus control device.

[0153] (11) The focus control device according to (8) or (9), The control unit In the second state, when the focal length changes within a range less than the threshold value, performing a process of reducing a specific frequency component from pixel data obtained by the second imaging element in the second state; setting the movable range in accordance with the phase difference signal obtained by the processing; Focus control device.

[0154] (12) The focus control device according to (11), The control unit a degree of reduction of the specific frequency component in the processing is set in accordance with the focal length; Focus control device.

[0155] (13) A focus control device according to any one of (1) to (13), the imaging optical system; A lens device comprising:

[0156] (14) A focus control device according to any one of (1) to (13), the first imaging element; An imaging device comprising:

[0157] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0158] This application is based on a Japanese patent application (Patent Application No. 2021-025528) filed on February 19, 2021, the contents of which are incorporated by reference into this application. [Industrial Applicability]

[0159] By applying the phase difference detection device of the present invention to an imaging device for broadcasting, it is possible to suppress unintended changes in the angle of view by the user. [Explanation of symbols]

[0160] 1 Lens device 3. Imaging device body 10 Imaging optical system 11 Focus Lens 12 Zoom Lens 15 Master lens group 16 Beam Splitter 16a Reflective surface 17 Image stabilization lens 20 AF optical system 21,26 Condenser lens 22 Mirror 27 Second image sensor 28 Control Unit 29 Drive mechanism 31 First image sensor 32 Image processing section 100, 100B, 100C, 100D Imaging device 101 LPF 121,122 Correlation curve 130,150 Compatibility Information 181 Optical LPF 201 AF area 202 Non-AF area 211 Focus position 212 Range of motion K1 optical axis

Claims

1. a branching unit that branches an optical path of subject light that has passed through an imaging optical system with a variable focal length into a first optical path that proceeds to a first imaging element and a second optical path other than the first optical path; a second image sensor that receives the subject light that has traveled through the second optical path and been pupil-divided and outputs a phase difference signal; a control unit that performs automatic focus control to drive a focus mechanism included in the imaging optical system based on the phase difference signal in a first state in which the focal length is equal to or greater than a threshold value; Equipped with The control unit In a second state in which the focal length is less than the threshold value, the automatic focus control is not executed, and a movable range of the focus mechanism is set in accordance with the phase difference signal obtained in the first state. Focus control device.

2. 2. The focus control device according to claim 1, The control unit In the second state, the movable range is set based on a driving state of the focus mechanism that is driven in accordance with the phase difference signal obtained in the first state. Focus control device.

3. 3. The focus control device according to claim 2, The control unit When the first state is shifted to the second state, the automatic focus control is stopped; setting the movable range based on the driving state of the focus mechanism; Focus control device.

4. 4. The focus control device according to claim 1, The control unit In the second state, the movable range is set to a width corresponding to the focal length. Focus control device.

5. 5. The focus control device according to claim 4, The control unit In the second state, the shorter the focal length, the wider the movable range is set. Focus control device.

6. 6. The focus control device according to claim 1, The control unit In the second state, the movable range is set to a width corresponding to a subject speed based on pixel data obtained by at least one of the first image sensor and the second image sensor. Focus control device.

7. 7. The focus control device according to claim 6, The control unit In the second state, the greater the object speed, the wider the movable range is set. Focus control device.

8. 8. The focus control device according to claim 1, The control unit When the focal length changes within a range less than the threshold value in the second state, the movable range is set in accordance with the phase difference signal obtained in the second state. Focus control device.

9. 9. The focus control device according to claim 8, The control unit In the second state, when the focal length changes within a range less than the threshold value, the movable range is set to be wider than when transitioning from the first state to the second state. Focus control device.

10. 10. The focus control device according to claim 8, The control unit In the second state, when the focal length changes within a range less than the threshold value, performing low-pass filtering on pixel data obtained by the second imaging element in the second state; setting the movable range in accordance with the phase difference signal obtained by the processing; Focus control device.

11. 11. The focus control device according to claim 10, The control unit a degree of reduction of high frequency components in the processing is set in accordance with the focal length; Focus control device.

12. 10. The focus control device according to claim 8, The control unit In the second state, when the focal length changes within a range less than the threshold value, performing a process of reducing a specific frequency component from pixel data obtained by the second imaging element in the second state; setting the movable range in accordance with the phase difference signal obtained by the processing; Focus control device.

13. 13. The focus control device according to claim 12, The control unit a degree of reduction of the specific frequency component in the processing is set in accordance with the focal length; Focus control device.

14. A focus control device according to any one of claims 1 to 13; the imaging optical system; A lens device comprising:

15. A focus control device according to any one of claims 1 to 13; the first imaging element; An imaging device comprising:

Images