Focus Detection Device

Abstract

To improve accuracy in prediction of focus detection.SOLUTION: A focus detector includes: an imaging section for capturing an image of a subject formed by a luminous flux having passed through an optical system having a focus lens; a pixel that is arranged in the imaging section and which outputs a signal on the basis of an electric charge photoelectrically converted and accumulated; a defocus calculation section for calculating a defocus amount which is an amount of deviation between a position of the image captured by the optical system and a position of the imaging section on the basis of the signal; a timing calculation section in which the pixel calculates accumulation timing for accumulating the electric charge; an acquisition section for acquiring a position of the focus lens; and an arithmetic section for calculating a drive amount of the focus lens on the basis of the position of the focus lens at the accumulation timing and the defocus amount calculated by the defocus calculation section.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention , jiao This relates to a point detection device. [Background technology]

[0002] There is known a camera that performs focus detection based on signals obtained by focus detection pixels of an image sensor (see Patent Document 1). When taking continuous photographs, there is a demand for improving the accuracy of focus detection prediction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-37959 A Summary of the Invention

[0004] A focus detection device according to a first aspect of the present invention includes an imaging unit that has a plurality of pixels that photoelectrically convert light that has passed through an optical system including a focus lens, accumulates electric charges, and outputs a signal used for focus detection, and that captures an object image formed by a light beam that has passed through the optical system; and a defocus calculation unit that calculates a defocus amount, which is the amount of deviation between the position of the object image and the position of an imaging surface of the imaging unit, based on the signal. a shutter curtain disposed between the optical system and the imaging unit, the shutter curtain moving to control the incidence of the light beam on the imaging surface; and a storage unit storing a moving characteristic of the shutter curtain; Position information of at least one selected focus area from among multiple focus areas and a travel characteristic of the shutter curtain stored in the storage unit. a timing calculation unit that calculates an accumulation timing at which the pixel corresponding to the at least one focus area accumulates charge based on the timing; an acquisition unit that acquires position information of the focus lens; and Calculated by timing calculation unit and a calculation unit that calculates a drive amount of the focus lens based on the position of the focus lens at the accumulation timing and the defocus amount calculated by the defocus calculation unit. [Brief description of the drawings]

[0005] [Figure 1]It is a perspective view illustrating a camera system. [Diagram 2] It is a diagram illustrating a focus area set within the imaging field of view. [Diagram 3] It is a block diagram explaining the main component configuration of the camera system. [Figure 4] It is a diagram illustrating the configuration of the focus detection device. [Diagram 5] It is a schematic diagram in which a frame corresponding to the focus area is superimposed on the corresponding position of the imaging surface. [Figure 6] FIG. 6(a) is a diagram showing the running curves of the front curtain and the rear curtain in the imaging of the (n + 1)-th frame, and FIG. 6(b) is a diagram explaining the AF operation performed during continuous shooting. [Figure 7] FIG. 7(a) is an enlarged diagram of the running curve of the rear curtain, and FIG. 7(b) is a diagram illustrating the relationship between the image height and the correction amount on the imaging surface. [Figure 8] FIG. 8 is a schematic diagram showing the pupil position and the light rays incident on the imaging surface. FIG. 8(a) shows the case of a standard exit pupil distance, FIG. 8(b) shows the case shorter than FIG. 8(a), and FIG. 8(c) shows the case longer than FIG. 8(a). [Figure 9] It is a diagram illustrating a table storing the corrected first and second times of the rear curtain. [Figure 10] It is a diagram illustrating the configuration of the focus detection device according to the second embodiment. [Figure 11] It is a diagram explaining the AF operation performed during continuous shooting.

Embodiments for Carrying Out the Invention

[0006] The focus detection device according to the embodiment of the present invention is mounted on, for example, an interchangeable-lens camera system. <Outline of AF Operation> First, an overview of AF (autofocus) operation will be described with reference to Figures 1 and 2. Figure 1 is a perspective view of a camera system 1 before an interchangeable lens 3 is attached to a camera body 2 according to one embodiment. The camera body 2 and the interchangeable lens 3 are coupled together by a bayonet structure of a body-side mount 210 and a lens-side mount 310. When the camera body 2 and the interchangeable lens 3 are coupled together, contact terminals provided near the respective mounts come into physical contact with each other and are electrically connected.

[0007] 2 shows a photographing field of view 50 captured by the imaging element 260 of the camera body 2. It also shows an example of a focus area P in the photographing field of view 50, along with a captured image. Twenty-one focus areas P are provided in the imaging field 50. A focus area is also called a focus detection area, focus detection position, distance measurement point, or autofocus (AF) point. It should be noted that the number and positions of the focus areas P shown in the figure are merely an example, and are not limited to the embodiment shown in FIG.

[0008] 4 detects the amount of defocus (amount of focus shift) between the position of a subject image formed by a light beam passing through the interchangeable lens 3 and the position of the imaging surface 260S of the image sensor 260 of the camera body 2, and therefore detects the amount of image shift (phase difference) of the subject image formed by a pair of light beams passing through different pupils of the interchangeable lens 3 for each focus area P. Then, for example, an AF operation is performed to adjust the position of the focus lens included in the interchangeable lens 3 so that the position of the subject image present in an area corresponding to a focus area P selected from a plurality of focus areas P is aligned (focused) with the position of the imaging surface 260S of the image sensor 260.

[0009] The focus area P to be used in the AF operation can be selected arbitrarily by the user's operation, or can be selected automatically by the camera body 2. In the AF mode in which the focus area P is selected by the user's operation, the focus detection device detects the amount of image shift of the subject image that exists in the focus area P selected by the user's operation. Then, the focus detection device performs the AF operation to focus on the subject that exists in the selected focus area P.

[0010] Furthermore, in the case of an AF mode in which the focus area P is automatically selected, the camera body 2 selects at least one of the above 21 focus areas P. For example, in the example shown in Fig. 2, when a mode for focusing on a person's face is selected, the camera body 2 selects two focus areas P(i) and P(ii) that are included in the person's face, and detects the amount of image shift of the subject image for each of the two focus areas P(i) and P(ii).

[0011] Of the two focus areas P(i) and P(ii), if P(ii) is, for example, the focus area that is closest (closest) to the camera system 1 or has the highest contrast, the focus detection device selects the focus area P(ii).Then, the focus detection device performs an AF operation to focus on a face part that exists in the selected focus area P(ii). The focus detection device can also perform AF operation to focus on the face part, taking into account the defocus amounts of both of the two focus areas P(i) and P(ii) selected as being included in the face part. For example, the average value of the two defocus amounts may be calculated and the focus lens may be driven (AF operation) with the calculated average defocus amount, or a weighted average may be calculated so that the two defocus amounts are within the depth of field as much as possible, and AF operation may be performed.

[0012] (First embodiment) The camera system 1 that performs the above-mentioned AF operation will be described in further detail below. Fig. 3 is a block diagram illustrating the configuration of the main parts of the camera system 1 according to the first embodiment. <Interchangeable lenses> The interchangeable lens 3 has a lens mount 310, a lens control unit 330, a lens communication unit 340, a lens storage unit 350, an imaging optical system 360, a lens driving unit 370, an aperture driving unit 380, and a vibration sensor 390. The lens driving unit 370 includes lens driving units 370a and 370b.

[0013] The annular lens side mount 310 is provided with a lens side terminal holding section 320. The lens side terminal holding section 320 has a plurality of lens side terminals arranged in an arc shape centered on the optical axis O. The plurality of lens side terminals include, for example, an attachment detection terminal that notifies the camera body 2 that the interchangeable lens 3 has been attached to the camera body 2, a communication terminal used for communication between the interchangeable lens 3 and the camera body 2, a power supply terminal through which power is supplied from the camera body 2 to the interchangeable lens 3, and a ground terminal (ground).

[0014] The lens side control unit 330 is composed of a microcomputer and its peripheral circuits, etc. The lens side control unit 330 executes a control program stored in the lens side storage unit 350 to control each unit of the interchangeable lens 3. The lens side control unit 330 is connected to the lens side communication unit 340, the lens side storage unit 350, the lens driving unit 370a, the lens driving unit 370b, the aperture driving unit 380, and the vibration sensor 390.

[0015] The lens side communication unit 340 performs a predetermined communication with the body side communication unit 240. The lens side communication unit 340 is connected to the lens side control unit 330 and the above-mentioned communication terminal. Through communication between the lens side communication unit 340 and the body side communication unit 240, an instruction to move the imaging optical system 360 (described later) and a transmission request for information indicating the state of a drive unit that drives the imaging optical system 360 are transmitted to the interchangeable lens 3. Furthermore, through communication between the lens side communication unit 340 and the body side communication unit 240, the drive state of the imaging optical system 360 and the like are transmitted from the interchangeable lens 3 to the camera body 2.

[0016] The state of the drive unit in the interchangeable lens 3 refers to the state in which the lens drive unit 370a and the lens drive unit 370b are driving the corresponding focus lens 361a and shake correction lens 361b, respectively, and the state after driving. Meanwhile, information indicating the positions of the focus lens 361a and shake correction lens 361b and the state of the drive unit of the interchangeable lens 3, information read out from the lens side memory unit 350, and the like are transmitted from the interchangeable lens 3 to the camera body 2.

[0017] The lens-side storage unit 350 is configured with a non-volatile storage medium. The lens-side storage unit 350 has data recording and reading controlled by the lens-side control unit 330. In addition to storing control programs and the like executed by the lens-side control unit 330, the lens-side storage unit 350 can also store data indicating the model name of the interchangeable lens 3 (also referred to as model name information) and data indicating the optical characteristics of the imaging optical system 360. The lens-side storage unit 350 is connected to the lens-side control unit 330.

[0018] The imaging optical system 360 guides subject light to an imaging surface 260S of an imaging element 260 in the camera body 2. An optical axis O of the imaging optical system 360 approximately coincides with the center positions of the lens side mount 310, the body side mount 210, and the imaging surface. The imaging optical system 360 includes, for example, a focus lens 361a, a shake correction lens 361b, and an aperture 362. At least a part of the imaging optical system 360 is configured to be movable in the direction of the optical axis O by a lens driving unit 370 or by manual operation. For example, the focus lens 361a is configured to be movable forward and backward in the direction of the optical axis O by the lens driving unit 370a. The movement of the focus lens 361a changes the position of the subject image formed by the imaging optical system 360. This causes the AF operation (focusing).

[0019] For example, the shake correction lens 361b is configured to be movable by the lens driving unit 370b in a direction intersecting the optical axis O. The movement of the shake correction lens 361b suppresses shaking (image shake) of the subject image on the imaging surface 260S of the image sensor 260. The shake correction by moving the shake correction lens 361b is one of the vibration reduction functions of the camera system 1.

[0020] The diaphragm 362 adjusts the amount of light incident on the image sensor 260. The diaphragm 362 is configured so that the aperture diameter (aperture value) can be changed by driving the diaphragm blades by the diaphragm driving unit 380 or by manual operation. The aperture diameter of the diaphragm 362 is configured so as to be detectable by an encoder of the diaphragm driving unit 380 or the like.

[0021] The lens driving unit 370a and the lens driving unit 370b are each composed of a motor or an actuator and a lens driving mechanism. The lens driving unit 370a moves the focus lens 361a along the optical axis O direction in response to a driving signal output from the lens side control unit 330. The movement direction, movement amount, movement speed, etc. of the focus lens 361a are instructed by, for example, the body side control unit 230. The position of the focus lens 361a is configured to be detectable by a position detection mechanism such as an encoder of the lens driving unit 370a.

[0022] The lens driving unit 370b moves the shake correction lens 361b in a direction intersecting the optical axis O in response to a driving signal output from the lens side control unit 330. The movement direction, movement amount, movement speed, etc. of the shake correction lens 361b are instructed, for example, from the lens side control unit 330. The position of the shake correction lens 361b is configured to be detectable by a hall sensor or the like of the lens driving unit 370b. The lens driving section 370a and the lens driving section 370b are each connected to the lens side control section 330.

[0023] The aperture drive unit 380 is composed of a motor and an aperture drive mechanism. The aperture drive unit 380 changes the opening diameter of the aperture 362 based on, for example, an instruction from the lens side control unit 330. The aperture drive unit 380 is connected to the lens side control unit 330.

[0024] The shake sensor 390 includes a gyro sensor or the like and detects shake of the camera system 1 due to hand shake or the like. The shake sensor 390 detects a shake angle component around the X-axis and a shake angle component around the Y-axis in FIG. 1. The shake sensor 390 may also include an acceleration sensor or the like and detect shake in a direction perpendicular to the optical axis O. A detection signal by the shake sensor 390 is sent to the lens side control unit 330. This performs so-called vibration prevention control. That is, based on the detection signal of the shake sensor 390 sent to the lens side control unit 330, the lens driving unit 370b moves the correction lens 361b in a direction intersecting the optical axis O, thereby suppressing shaking (image blur) of the subject image on the imaging surface 260S of the imaging element 260.

[0025] <Camera body> The camera body 2 has a body side mount 210, a body side control unit 230, a body side communication unit 240, a power supply unit 250, a shutter device 255, an image sensor 260, a sensor driving unit 265, a signal processing unit 270, an operation member 280, and a display unit 290. The sensor driving unit 265 is used in the second embodiment, and therefore may be omitted in the first embodiment.

[0026] The annular body-side mount 210 is provided with a body-side terminal holder 220. The body-side terminal holder 220 has a plurality of body-side terminals, and comes into contact with the lens-side terminals described above. Like the lens-side terminals, the plurality of body-side terminals also include, for example, an attachment detection terminal that notifies the camera body 2 that the interchangeable lens 3 has been attached to the camera body 2, a communication terminal used for communication between the camera body 2 and the interchangeable lens 3, a power supply terminal through which power is supplied from the camera body 2 to the interchangeable lens 3, and a ground terminal (ground).

[0027] The body side control unit 230 is composed of a microcomputer and its peripheral circuits, etc. The body side control unit 230 executes a control program stored in the storage unit 235 to control each unit in the camera body 2. The body side control unit 230 is connected to a body side communication unit 240, a power supply unit 250, a shutter device 255, an image sensor 260, a sensor driving unit 265, a signal processing unit 270, an operation member 280, and a display unit 290.

[0028] The body side control unit 230 includes a storage unit 235. Recording and reading of data in the storage unit 235 is controlled by the body side control unit 230. The storage unit 235 stores the control programs and the like executed by the body side control unit 230, and can also store model name information of the interchangeable lens 3 received by the body side communication unit 240, data indicating the optical characteristics of the interchangeable lens 3, and the like.

[0029] The body side communication unit 240 performs the above-mentioned communication with the lens side communication unit 340. The body side communication unit 240 is connected to the body side control unit 230 and the above-mentioned multiple body side terminals. The power supply unit 250 converts the voltage of a battery (not shown) into a voltage used by each part of the camera system 1, and supplies it to each part of the camera body 2 and the interchangeable lens 3. The power supply unit 250 can switch power supply on and off for each power supply destination according to instructions from the body side control unit 230. The power supply unit 250 is connected to the body side control unit 230 and the above-mentioned power supply terminal.

[0030] The shutter device 255 is a focal plane shutter arranged in front of the image sensor, and has a front curtain, a rear curtain, and an actuator mechanism for driving them. The opening and closing of the shutter device 255 is controlled by the body side control unit 230. When the shutter device 255 (front curtain) is opened, light from the subject is guided to the imaging surface 260S of the image sensor 260. When the shutter device 255 (rear curtain) is closed, the light from the subject is blocked.

[0031] The imaging element 260 is a solid-state imaging element such as a CMOS image sensor or a CCD image sensor. The imaging element 260 captures a subject image formed on an imaging surface 260S in response to a control signal from the body side control unit 230, and outputs an imaging signal. The imaging element 260 is connected to the body side control unit 230 and the signal processing unit 270.

[0032] The image sensor 260 has pixels for generating an image (referred to as imaging pixels) and pixels for focus detection (referred to as focus detection pixels) arranged on an imaging surface 260S. Signals generated by the imaging pixels (hereinafter referred to as imaging pixel signals) are used to generate image data by a signal processing unit 270, which will be described later. Furthermore, signals generated by the focus detection pixels (hereinafter referred to as focus detection pixel signals) are used for focus detection processing by the signal processing unit 270, which will be described later, to detect the focus state of an image formed by the interchangeable lens 3. The image sensor 260 may be configured to include pixels that output signals that can be used for both imaging and focus detection.

[0033] The sensor driving unit 265 is composed of, for example, an actuator and a sensor driving mechanism. The sensor driving unit 265 moves the image sensor 260 in a direction intersecting the optical axis O based on an instruction output from the body side control unit 230. The movement of the image sensor 260 reduces blurring of the subject image on the imaging surface of the image sensor 260 (image shake). The shake correction that moves the image sensor 260 is one of the vibration reduction functions that the camera system 1 has. The position of the moving image sensor 260 can be detected by a Hall sensor or the like of the sensor driving unit 265. The direction, amount, and speed of movement of the image sensor 260 are instructed by, for example, the body side control unit 230. The sensor driving unit 265 is connected to the body side control unit 230.

[0034] The signal processing unit 270 generates image data by performing a predetermined image processing on the imaging pixel signals output from the imaging element 260. The generated image data is recorded in a predetermined file format on a storage medium (memory card) (not shown) and is used to display a confirmation image of the captured image on the display unit 290 or to display a through image before shooting. The signal processing unit 270 is connected to the body side control unit 230, the imaging element 260, and the display unit 290.

[0035] Furthermore, the signal processing unit 270 uses the focus detection pixel signals output from the image sensor 260 to calculate a defocus amount, which is the difference between the position of the subject image formed by the interchangeable lens 3 by a phase difference detection method and the imaging surface 260S (FIG. 4) of the image sensor 260. The signal processing unit 270 calculates the amount of movement of the focus lens 361a to the in-focus position, which is the position of the focus lens 361a where the target subject image is focused on the imaging surface 260S, based on the calculated defocus amount and the position of the focus lens 361a at the time the focus detection pixel signals are acquired. A focus drive instruction based on the amount of movement of the focus lens 361a calculated by this focus detection calculation is transmitted from the camera body 2 to the interchangeable lens 3 together with data indicating the movement direction, amount of movement, etc. of the focus lens 361a.

[0036] An operation member 280 including a release button, an operation switch, etc. is provided on the exterior surface of the camera body 2. A user operates the operation member 280 to give instructions for shooting, setting shooting conditions, etc. The operation member 280 sends an operation signal to the body side control unit 230 according to the user's operation.

[0037] The display unit 290 is configured with, for example, a liquid crystal display panel. The display unit 290 displays an image based on image data processed by the signal processing unit 270, an operation menu screen, and the like, in response to an instruction from the body side control unit 230. The display unit 290 may also include a touch panel and serve as part of the operation member 280. The display unit 290 is connected to the body side control unit 230 and the signal processing unit 270.

[0038] The camera body 2 sends, via the communication described above, for example, a focus drive instruction, an instruction to start an image stabilization operation, a diaphragm drive instruction, a request for information transmission, information on the camera body 2 (imaging mode information, ISO sensitivity, whether video recording is in progress, etc.) to the interchangeable lens 3. In response to an instruction from the camera body 2, the interchangeable lens 3 drives the focus lens 361a, starts an image stabilization operation, and drives the diaphragm 362.

[0039] On the other hand, the interchangeable lens 3 sends, via the communication described above, for example, information indicating the optical characteristics of the imaging optical system 360, the position of the focus lens 361a, the amount of shake detected by the shake sensor 390, the amount of shake corrected by the interchangeable lens 3, information requested by the camera body 2, etc. to the camera body 2.

[0040] FIG. 4 is a diagram for explaining the configuration of the focus detection device according to the first embodiment among the configurations illustrated in FIG. 3. FIG. 4 shows a lens-side control unit 330, a lens-side communication unit 340, a focus lens 361a, a lens drive unit 370a, a body-side control unit 230, a body-side communication unit 240, a shutter device 255, an imaging element 260, and a signal processing unit 270. As described above, the imaging element 260 has an imaging surface 260S on which a light beam from the imaging optical system 360 is incident. The shutter device 255 is disposed in front of the imaging surface 260S (on the imaging optical system 360 side). The shutter device includes a front curtain 255a and a rear curtain 255b. The front curtain 255a and the rear curtain 255b each consist of a plurality of shutter blades and travel downward and upward, respectively, in the FIG. 4 screen. FIG. 4 shows a fully open shutter state before the front curtain 255a has finished opening downward and all the shutter blades of the rear curtain 255b are waiting above to close, indicating a state in which a light beam from the imaging optical system 360 is incident on the imaging surface 260S.

[0041] <Explanation of AF operation> The following describes the AF operation performed during continuous shooting in this embodiment, in which multiple images are continuously shot while the release button is pressed. The camera body 2 captures multiple images one by one while the release button is being pressed all the way down. The body side control unit 230 causes the image sensor 260 to start a charge accumulation operation, and drives the front curtain 255a of the shutter device 255 to open. The body side control unit 230 then drives the rear curtain 255b of the shutter device 255 to close, and causes the signal processing unit 270 to perform focus detection calculations based on the focus detection pixel signals transferred from the image sensor 260 to the signal processing unit 270.

[0042] Based on the focus detection calculation result, the body side control unit 230 instructs the lens side control unit 330 to perform focus driving via the body side communication unit 240 and the lens side communication unit 340. In response to the focus driving instruction, the lens side control unit 330 moves the focus lens 361a by the lens driving unit 370a (focus control).

[0043] Fig. 5 is a schematic diagram in which 21 frames PS corresponding to the focus areas P in Fig. 2 are superimposed on corresponding positions on the imaging plane 260S. The position corresponding to the optical axis O of the imaging plane 260S is set to image height y = 0. The short side direction of the imaging plane 260S (the vertical direction of the image) is set to image height y = -a to +a. The center position of the frame PS on the imaging plane 260S is set to image height y = -b to +b in the short side direction of the imaging screen 260S. As explained using Figure 4, the front curtain 255a and rear curtain 255b of the shutter device 255 each consist of multiple shutter blades, and each travels from top to bottom as shown by the arrows in Figure 5. Figure 5 shows a state in which all of the shutter blades of the front curtain 255a have finished opening and moving downward, and all of the shutter blades of the rear curtain 255b are waiting above before closing.

[0044] The movement amount of the focus lens 361a calculated by the signal processing unit 270 is the movement amount to the in-focus position calculated starting from the position of the focus lens 361a at the time when the focus detection pixel signal used to calculate the defocus amount was acquired. The time when the focus detection pixel signal was acquired is the exposure period (charge accumulation period) of the focus detection pixels arranged at the position of the frame PS corresponding to the adopted focus area P, and corresponds to the time from the opening time when the front curtain 255a of the shutter device 255 passes the position of the frame PS to the light blocking time when the rear curtain 255b passes.

[0045] 6 is a timing chart for explaining the AF operation performed during continuous shooting. The signal processing unit 270 performs charge accumulation when the front curtain 255a of the shutter device 255 is opened at the nth frame, the n+1th frame, ..., and performs a predetermined image processing on the imaging pixel signals read from the image sensor 260 that has completed charge accumulation when the rear curtain 255b is closed and transferred to the signal processing unit 270, to generate an image for one frame. The signal processing unit 270 also performs focus detection calculation based on the focus detection pixel signals read from the image sensor 260 that has completed charge accumulation and transferred to the signal processing unit 270. The body side control unit 230 instructs the interchangeable lens 3 to perform focus drive for each captured frame based on the focus detection calculation result by the signal processing unit 270. For example, the focus drive instruction is performed between accumulation periods of the image sensor 260.

[0046] In the example of Fig. 6, a focus drive instruction based on the focus detection pixel signal acquired when capturing the previous frame is transmitted from the camera body 2 to the interchangeable lens 3 before capturing the next frame. Fig. 6 shows an example in which the focus lens 361a is moved even during charge accumulation in the image sensor 260.

[0047] The following description focuses on the n+1th frame. In Fig. 6(a), the horizontal axis is time and the vertical axis is the vertical position of the image sensor 260, and curve 61 indicates the travel curve of the front curtain 255a in capturing the n+1th frame (the rearmost end position in the travel direction of the shutter blades of the front curtain 255a). Curve 62 indicates the travel curve of the rear curtain 255b in capturing the n+1th frame (the most extreme position in the travel direction of the shutter blades of the rear curtain 255a). The body side control unit 230 outputs a signal to the shutter device 255 to release the front curtain 255a at time t0, and outputs a signal to the shutter device 255 to release the rear curtain 255b at time t2.

[0048] A first time and a second time are set as design values ​​for the shutter device 255. The first time refers to the time from when a signal to release the shutter curtain is input to when the shutter curtain passes the position of image height y=+a. First, the movement of the front curtain 255a will be described. Before the shutter release, the front curtain 255a covers the entire imaging surface 260S, and the rearmost end of the front curtain 255a is located at a position higher (farther) than the image height y = +a. When a signal to release the front curtain 255a is input and the front curtain 255a actually starts to move (arrow in Fig. 5), even in the initial stage, the rearmost end of the front curtain 255a moves from a position higher (farther) than the image height y = +a. When the first time has elapsed (time t1 described later), the rearmost end of the front curtain 255a reaches the uppermost end (image height y = +a) of the imaging surface 260a. After that, the rearmost end of the front curtain 255a moves within the image height -a < y < +a of the imaging surface 260a and stops after exceeding y = -a (moving to a position farther than y = -a). While the front curtain 255a is moving within the image height -a < y < +a, a light beam from the imaging optical system 360 is incident on the imaging surface 260S. That is, when the first time has elapsed, the uppermost part of the imaging surface 260S is opened, and the incidence of the light beam on the uppermost part of the imaging surface 260S is started. As described above, the first time is the delay time from the signal to release the front curtain 255a until the incidence of the light beam on the uppermost part of the imaging surface 260S is started, and is also referred to as the face detection time. The second time refers to the time from when the front curtain passes the position of the image height y = +a until the time (time t4 described later) when it passes the position of the image height y = -a. That is, the second time is the time when the rearmost end of the front curtain 255a passes through the entire imaging surface 260S, and is also referred to as the curtain running time. Before the shutter release, the foremost end of the rear curtain 255b is located at a position higher (farther) than the image height y = +a. When a signal to release the rear curtain 255b is input and the rear curtain 255b actually starts to move, until the first time has elapsed, the foremost end of the rear curtain 255b moves from a position higher (farther) than the image height y = +a. When the first time has elapsed, the foremost end of the rear curtain 255b reaches the uppermost end (image height y = +a) of the imaging surface 260a. After that, the foremost end of the rear curtain 255a moves within the image height -a < y < +a of the imaging surface 260a and stops after exceeding y = -a (moving to a position farther than y = -a). The foremost end of the rear curtain 255b also passes from the image height y = +a to the position of the image height y = -a during the second time. In this embodiment, the first time and the second time for the front curtain 255a are called the front curtain first time and the front curtain second time. Also, the first time and the second time for the rear curtain 255b are called the rear curtain first time and the rear curtain second time. In this embodiment, the front curtain first time and the rear curtain first time are configured to be approximately equal, and the front curtain second time and the rear curtain second time are configured to be approximately equal.

[0049] As described above, the rear end of the front curtain 255a passes the position of image height y=+a at time t1 when the first front curtain time has elapsed from time t0. As a result, the front curtain 255a starts to open, and the top of the imaging surface 260S opens (appears) (light starts to enter the imaging element 260). The rear end of the front curtain 255a passes the position of image height y=+b (FIG. 5, position of frame PS51) at time tb1, passes the position of image height y=0 (FIG. 5, position of frame PS52) at time t3, passes the position of image height y=-b (FIG. 5, position of frame PS53) at time tb3, and passes the position of image height y=-a at time t4. The period from time t1 to time t4 is the second front curtain time.

[0050] The leading edge of the rear curtain 255b passes the position of image height y=+a at time t4, which is the rear curtain first time after time t2. This causes the rear curtain 255b to start closing (start blocking light from the image sensor 260). The rear curtain 255b passes the position of image height y=+b (the position of frame PS51 in FIG. 5) at time tb2, passes the position of image height y=0 (the position of frame PS52 in FIG. 5) at time t5, passes the position of image height y=-b (the position of frame PS53 in FIG. 5) at time tb4, and passes the position of image height y=-a at time t6. The period from time t4 to time t6 is the rear curtain second time.

[0051] <Calculation of exposure timing based on image height> 5, in this embodiment, the front curtain 255a and rear curtain 255b of the shutter device 255 move in the negative direction of the Y axis (direction of the arrow). Therefore, frames PS51, PS52, and PS53 at positions with different image heights in the Y axis direction on the imaging plane 260S have different exposure timings for the focus detection pixels because the rearmost end of the front curtain 255a and the foremost end of the rear curtain 255b pass through at different times.

[0052] Therefore, the body side control unit 230 calculates the exposure timing of the focus detection pixels based on the image height of the frame PS corresponding to the adopted focus area P, and calculates the position of the focus lens 361a at the calculated exposure timing. Position information indicating the position of the focus lens 361a is indicated by a circle (○) in Fig. 6(b). The position information of the focus lens 361a is transmitted from the lens side control unit 330 to the body side control unit 230 by communication between the interchangeable lens 3 and the camera body 2 that is performed at predetermined time intervals.

[0053] The body side control unit 230 calculates the position of the focus lens 361a at the time when the focus detection pixel signal was acquired based on the position information of the focus lens 361a transmitted from the lens side control unit 330 and the calculated exposure timing. The body side control unit 230 sends the calculated position of the focus lens 361a to the signal processing unit 270. With this configuration, the signal processing unit 270 can appropriately calculate the amount of movement of the focus lens 361a to the in-focus position, starting from the position of the focus lens 361a at the time when the focus detection pixel signal was acquired.

[0054] When the focus lens 361a moves even during the accumulation period of the image sensor 260, the body side control unit 230 treats the average position obtained by averaging the positions of the focus lens 361a during the accumulation period as the position of the focus lens 361a at the time when the focus detection pixel signal was acquired. The body side control unit 230 calculates the average position based on the position information of the focus lens 361a transmitted from the lens side control unit 330 and the exposure timing calculated as described above. By configuring in this manner, the signal processing unit 270 can appropriately calculate the amount of movement of the focus lens 361a to the in-focus position, starting from the average position of the focus lens 361a at the time when the focus detection pixel signal was acquired while the focus lens 361a was moving.

[0055] <Calculation of exposure timing according to shutter running characteristics> Generally, the focal plane shutter that constitutes the shutter device 255 is biased by a spring or the like. Therefore, the traveling speeds of the rearmost end of the front curtain 255a and the foremost end of the rear curtain 255b do not remain constant within the above-mentioned second front curtain time and second rear curtain time. For example, in the first half of the second front curtain time and the second rear curtain time (image height y = +a to y = +b), the released front curtain 255a and rear curtain 255b gradually accelerate from a slow speed state. On the other hand, in the second half of the second front curtain time and the second rear curtain time, since the traveling speeds of the front curtain 255a and the rear curtain 255b have reached the designed speed, they travel at a substantially constant speed from image height y = 0 to y = -a.

[0056] FIG. 7(a) is an enlarged view of the traveling curve of the foremost end of the rear curtain 255b, and is a diagram illustrating the relationship between the image height y on the imaging surface 260S and the time t (FIG. 6(a)) when the rear curtain 255b passes. The actual traveling curve 71 of the foremost end of the rear curtain 255b is shown by a solid line, and an approximate straight line 72 approximating the traveling curve 71 is shown by a broken line. As the approximate straight line 72, one approximate straight line may be obtained over the entire range (y = +a to y = -a), or two approximate straight lines 72 may be obtained separately for each of y > 0 and y < 0. Alternatively, the straight line 72 may be divided into two, for example, at the boundary where the speed change of the rear curtain 255b changes significantly, such as y > +b and +b < y, or further divided into three, y > +b, +b < y < -b, and -b < y. As shown in FIG. 6(a), the foremost end of the rear curtain 255b released at time t2 passes through the image height y = +a at time t4, passes through the image height y = +b at time tb2, and passes through the image height y = 0 at time t5. Further, it passes through the image height y = -b at time tb4 and passes through the image height y = -a at time t6.

[0057] As shown by the traveling curve 71, the traveling characteristics of the foremost end of the rear curtain 255b of the shutter device 255 are non-linear in which the curtain traveling time and the traveling distance are not proportional. Therefore, when calculating the exposure timing of the focus detection pixels based on the image height of the position of the frame PS corresponding to the focus area P adopted by the body side control unit 230, simply shifting the exposure timing in proportion to the image height does not result in the calculated exposure timing matching the timing when the shutter device 255 actually opens.

[0058] When calculating the exposure timing of the focus detection pixels of the frame PS corresponding to the adopted focus area P, the body side control unit 230 according to this embodiment calculates the exposure timing in accordance with the running characteristics of the shutter device 255. To be more specific, the body side control unit 230 linearly approximates the running curve 71 as if there was a linear relationship in which the curtain running time and the running distance are proportional to each other. When linearly approximating the running curve 71 described above, two approximation lines 72 are calculated by dividing the curve into the regions y>0 and y<0. The exposure timing for each frame PS is calculated using the calculated approximation line 72. The time to pass through each frame PS is calculated using the approximation line 72 that is proportional to the image height, calculated for y>0 and y<0, and the exposure timing is calculated. Note that the exposure timing may be calculated using the travel curve 71 without using the approximation line 72, and the difference between the actual travel curve 71 and the approximation line 72 may be corrected for the linearly approximated approximation line 72. Fig. 7(b) is a diagram illustrating the relationship between the image height y on the imaging plane 260S and the amount of correction when correcting the difference. With this configuration, the exposure timing can be calculated simply and accurately.

[0059] Calculation of the exposure timing for frames PS51, PS52, and PS53 will be described with reference to Figures 5 to 7. Data showing the approximated line 72 in Figure 7(a) is stored in the memory unit 235 of the body side control unit 230. The time at which the leading edge of the rear curtain 255b passes is calculated based on this approximated line 72. For example, in frame PS52 in Figure 5, the time at which the leading edge of the rear curtain 255b passes y=0 is calculated from the approximated line 72 in Figure 7 as exposure timing t5. The travel curve 71 may be used for the calculation. Data showing the travel curve 71 in FIG. 7A is stored in the storage unit 235 of the body side control unit 230. For example, the travel curve of the rear curtain 255b is measured during manufacturing and stored in the storage unit 235. Instead of storing the travel curve 71, the approximation curve 72 and the correction amount in FIG. 7B may be stored. In that case, the travel curve 71 in FIG. 7A can be calculated by correcting the approximation line 72 by the correction amount in FIG. 7B. The correction amount in FIG. 7B may be obtained by actually measuring the curtain travel time of the shutter device 255 in advance, or may be a value based on the design value of the shutter device 255. The body side control unit 230 calculates the time when the leading edge of the rear curtain 255b passes based on the travel curve 71, starting from the time t2 when a signal to release the rear curtain 255b is output to the shutter device 255. In this embodiment, the exposure timing is determined from the travel curve 71 or approximate straight line 72 of the leading edge of the rear curtain 255b, but the rear edge of the front curtain 255a may be used instead. Also, the timing at which the leading edge of the front curtain 255a passes through each frame PS and the timing at which the leading edge of the rear curtain 255b passes through each frame PS may be calculated, and the timing midway between the two may be calculated as the exposure timing.

[0060] (Frame PS51) When calculating the exposure timing of the frame PS51, the body side control unit 230 calculates the rear curtain first time (51) and the rear curtain second time (51) based on the approximation line 72 to obtain the time when the leading end of the rear curtain 255b passes through the frame PS51. The rear curtain first time (51) is the time calculated based on the approximation line 72 from when a signal to release the rear curtain 255b is input until the leading end of the rear curtain 255b reaches the image height y=+a. The rear curtain second time (51) is the time calculated based on the approximation line 72 for the leading end of the rear curtain 255b to travel from the image height y=+a to the image height y=+b where the frame PS51 is located. That is, the rear curtain first time (51) corresponds to the time from time t2 to time t4 (see FIG. 6), and the rear curtain second time (51) corresponds to the time from time t4 to time tb2 (see FIG. 7). Time tb2 is the accumulation end time at the position of frame PS51. The body side control unit 230 calculates time tb1, which is the accumulation time going back from time tb2, and sets this as the accumulation start time. Through the above calculations, the exposure timing of frame PS51 is from time tb1 to time tb2. In this embodiment, the accumulation end time is the time when the rear curtain 255b passes through the center of frame PS51, but the accumulation end time may also be the time when the rear curtain 255b passes through one side of frame PS52 in the positive direction on the Y axis (the topmost end of frame PS52) or the time when the rear curtain 255b passes through one side of frame PS52 in the negative direction on the Y axis (the bottommost end of frame PS52).

[0061] (Frame PS52) When calculating the exposure timing of the frame PS52, the body side control unit 230 calculates the rear curtain first time (52) and the rear curtain second time (52) based on the approximation line 72 to obtain the time when the leading end of the rear curtain 255b passes through the frame PS52. The rear curtain first time (52) is the time calculated based on the approximation line 72 from when a signal to release the rear curtain 255b is input until the leading end of the rear curtain 255b reaches the image height y=+a, and is the same as the rear curtain first time (51) described above. The rear curtain second time (52) is the time calculated based on the approximation line 72 for the leading end of the rear curtain 255b to travel from the image height y=+a to the image height y=0 where the frame PS52 is located. That is, the rear curtain first time (52) corresponds to the time from time t2 to time t4 (see FIG. 6), and the rear curtain second time (52) corresponds to the time from time t4 to time t5 (see FIG. 7). Time t5 is the accumulation end time at the position of frame PS52. The body side control unit 230 calculates time t3, which is the accumulation time going back from time t5, and sets this as the accumulation start time. Through the above calculations, the exposure timing of frame PS52 is from time t3 to time t5.

[0062] (Frame PS53) When calculating the exposure timing of the frame PS53, the body side control unit 230 calculates the rear curtain first time (53) and the rear curtain second time (53) based on the approximation line 72 to obtain the time when the leading end of the rear curtain 255b passes through the frame PS53. The rear curtain first time (53) is the time calculated based on the approximation line 72 from when a signal to release the rear curtain 255b is input until the leading end of the rear curtain 255b reaches the image height y = +a, and is the same as the rear curtain first time (51) described above. The rear curtain second time (53) is the time calculated based on the approximation line 72 for the leading end of the rear curtain 255b to travel from the image height y = +a to the image height y = -b where the frame PS53 is located. That is, the rear curtain first time (53) corresponds to the time from time t2 to time t4 (see FIG. 6), and the rear curtain second time (51) corresponds to the time from time t4 to time tb4 (see FIG. 7). Time tb4 is the accumulation end time at the position of frame PS53. The body side control unit 230 calculates time tb3, which is the accumulation time going back from time tb4, and sets this as the accumulation start time. Through the above calculations, the exposure timing of frame PS53 is from time tb3 to time tb4.

[0063] The above explanation can be summarized as follows: Because the front curtain 255a and rear curtain 255b of the shutter device 255 move in the Y-axis direction, the rearmost end of the front curtain 255a and the frontmost end of the rear curtain 255b pass through frames PS51, PS52, and PS53 at positions with different image heights in the Y-axis direction on the imaging plane 260S at different times. This causes the exposure timing of the focus detection pixels in the frames PS51, PS52, and PS53 to differ.

[0064] If the exposure timing of the focus detection pixels in the frames PS51, PS52, and PS53 is different, when the focus lens 361a is moving, the average position of the focus lens 361a at the time when the focus detection pixel signals are acquired in the frames PS51, PS52, and PS53 will be different.

[0065] However, the body side control unit 230 calculates the exposure timing of the focus detection pixels in the corresponding frames PS51, PS52, and PS53 based on the image height of the frame PS corresponding to the adopted focus area P, and calculates the average position of the focus lens 361a at the calculated exposure timing. As shown in FIG. 6B, the body side control unit 230 of the camera body 2 calculates the average position of the focus lens 361a at the time when the focus detection pixel signal is acquired based on the position information of the focus lens 361a transmitted from the lens side control unit 330 and the calculated exposure timing. The body side control unit 230 sends the calculated average position of the focus lens 361a to the signal processing unit 270. With this configuration, the signal processing unit 270 can appropriately calculate the movement amount of the focus lens 361a to the in-focus position starting from the average position of the focus lens 361a at the time when the focus detection pixel signal is acquired.

[0066] <Changes based on pupil position> The lengths of the rear curtain first time and the rear curtain second time are corrected depending on the pupil position of the imaging optical system 360. In this embodiment, the distance from the position of the exit pupil of the imaging optical system 360 to the imaging plane 260S is called the pupil distance. FIG. 8 is a schematic diagram showing the pupil distance and light rays incident on the imaging plane 260S. FIGS. 8(a), (b), and (c) show cases where the pupil distances of the optical systems are different. The pupil distance is (b)<(a)<(c).

[0067] Generally, due to the optical characteristics of the imaging optical system 360, light that has passed through the imaging optical system 360 is incident approximately perpendicularly on the central portion of the imaging plane 260S close to the optical axis O, whereas the higher the image height is on the imaging plane 260S, the more obliquely the light that has passed through the imaging optical system 360 is incident. The angle at which the light that has passed through the imaging optical system 360 is obliquely incident increases as the pupil distance becomes shorter.

[0068] The position where the shutter curtains 255a and 255b travel is closer to the imaging optical system 360 than the imaging surface 260S. Therefore, as can be clearly seen in FIG. 8(b), when a light ray is obliquely incident on a position with a high image height, the image height h1 at which the shutter curtains 255a and 255b of the shutter device 255, which are located closer to the imaging optical system 360 than the imaging surface 260S, block the light ray is different from the image height h2 of the light ray that actually enters the imaging surface 260S. The difference between the image height h1 and the image height h2 increases as the pupil distance becomes shorter. The difference g2 between the image height h1 and the image height h2 in FIG. 8(b) is larger than the difference g1 between the image height h1 and the image height h2 in FIG. 8(a), and the difference g1 between the image height h1 and the image height h2 in FIG. 8(a) is larger than the difference g3 between the image height h1 and the image height h2 in FIG. 8(c).

[0069] The lens side control unit 330 changes the rear curtain first time and the rear curtain second time for the rear curtain 255b depending on the pupil distance. Specifically, the shorter the pupil distance of the imaging optical system 360, the longer the rear curtain first time is corrected, and the shorter the end time of the rear curtain second time is corrected. By configuring in this way, it is possible to appropriately determine the exposure timing of the focus detection pixels in consideration of the difference in exposure time (charge accumulation time) caused by the difference between the image height h1 at which the shutter curtains 255a and 255b exist and the image height h2 of the light beam actually incident on the imaging surface 260S depending on the pupil distance of the imaging optical system 360.

[0070] In addition, by appropriately determining the exposure timing of the focus detection pixels while taking into account the difference in exposure time (charge accumulation time) caused by the difference between the image height h1 at which the shutter curtain exists and the image height h2 of the light ray actually incident on the imaging surface 260S, the signal processing unit 270 can appropriately calculate the amount of movement of the focus lens 361a to the in-focus position, starting from the average position of the focus lens 361a during the exposure time (charge accumulation time) when the focus detection pixel signal was acquired.

[0071] The corrected rear curtain first time and rear curtain second time may be stored as table values ​​in the storage unit 235. Fig. 9 is a diagram illustrating the table values. The table of Fig. 9 stores values ​​of the first time (51), the second time (51), the first time (52), the second time (52), the first time (53), and the second time (53) of frames PS51, PS52, and PS53 at positions with different image heights in the Y-axis direction on the imaging plane 260S for an interchangeable lens A corresponding to the pupil position of Fig. 8(a), an interchangeable lens B corresponding to the pupil position of Fig. 8(b), and an interchangeable lens C corresponding to the pupil position of Fig. 8(c).

[0072] In this embodiment, the front curtain 1st hour and the rear curtain 1st time are substantially equal, and the front curtain 2nd hour and the rear curtain 2nd time are substantially equal, so one table is sufficient. If the front curtain 1st hour and the rear curtain 1st time are different, or the front curtain 2nd hour and the rear curtain 2nd time are different, for example, when the travel performance of the front curtain 255a and the rear curtain 255b are different, a table corresponding to each of the cases may be prepared. When there are four or more types of interchangeable lenses 3, values ​​for the additional interchangeable lenses can be added to the table in Fig. 9. When adding focus areas other than the frames PS51, PS52, and PS53 at positions where the image heights differ in the Y-axis direction on the imaging surface 260S, values ​​for the added positions can be added to the table in Fig. 9.

[0073] According to the above-described first embodiment, the following advantageous effects can be obtained. (1) In this embodiment, during continuous shooting, the focus lens is driven for the next image capture based on the position of the focus lens while charge is being accumulated in the focus detection pixels and the calculated defocus amount, thereby increasing the focusing speed of the focus lens. In addition, since imaging is performed while the focus lens is moving, the imaging speed can be increased, and the continuous shooting speed can also be increased. Even if the travel speed of the rear shutter curtain is not constant and has nonlinear travel characteristics, the exposure timing of the focus detection pixels can be appropriately calculated based on the time when the rear shutter curtain blocks light. Calculating the appropriate exposure timing of the focus detection pixels leads to correctly calculating the position of the focus lens, which is the basis for calculating the drive amount of the focus lens.

[0074] (2) The exposure timing of the focus detection pixels can be appropriately calculated based on the time at which the rear curtain blocks light, which is based on the travel curve of the shutter device.

[0075] (3) The light blocking timing (opening time) corresponding to the position of the frame corresponding to the focus area (focused area) within the image sensor is calculated. With this configuration, even if the time when the rear curtain passes is different for frames at multiple positions with different image heights in the travel direction of the rear curtain (Y-axis direction) on the image plane, the exposure timing of the focus detection pixels can be appropriately calculated for each position.

[0076] (4) The light blocking timing is calculated using information on the exit pupil distance of the imaging optical system. With this configuration, it is possible to appropriately calculate the exposure timing of the focus detection pixels, taking into account the difference in exposure time (charge accumulation time) caused by the difference between the image height at which the rear curtain blocks light rays and the image height of the light rays that actually enter the imaging surface, due to the difference in the exit pupil distance of the imaging optical system.

[0077] (5) The shutter has a front curtain that starts exposure of the image sensor and a rear curtain that blocks light. With this configuration, the exposure timing of the focus detection pixels can be appropriately calculated based on the exposure start time of the front curtain and the light blocking time of the rear curtain.

[0078] Second embodiment In the second embodiment, shake correction is performed by using a sensor driving unit 265 of the camera body 2 to move the image sensor 260 in a direction intersecting with the optical axis O. The main configuration of the camera system 1 according to the second embodiment is similar to that shown in FIG. 3. The body side control unit 230 corrects the lengths of the rear curtain first time and the rear curtain second time described in the first embodiment depending on the amount of movement (moved position) of the image sensor 260 in the direction intersecting with the optical axis O. This will be described in detail below.

[0079] Fig. 10 is a diagram for explaining the configuration of the focus detection device according to the second embodiment from the configuration exemplified in Fig. 3. Fig. 10 shows the lens side control unit 330, the lens side communication unit 340, the focus lens 361a, the lens driving unit 370a, the shake correction lens 361b, the lens driving unit 370b, the shake sensor 390, the body side control unit 230, the body side communication unit 240, the shutter device 255, the image sensor 260, the sensor driving unit 265, and the signal processing unit 270.

[0080] <Explanation of shake correction operation> The shake sensor 390 is composed of, for example, an angular velocity sensor 390a and an acceleration sensor 390b. The angular velocity sensor 390a detects the angular velocity generated by the rotational motion of the camera system 1. The angular velocity sensor 390a detects rotations around, for example, an axis parallel to the X-axis, an axis parallel to the Y-axis, and an axis parallel to the optical axis O, and sends detection signals to the lens side control unit 330. The angular velocity sensor 390a is also called a gyro sensor.

[0081] Furthermore, the acceleration sensor 390b detects acceleration occurring due to translational motion of the camera system 1. The acceleration sensor 390b detects acceleration in the direction of an axis parallel to the X-axis and an axis parallel to the Y-axis, for example, and sends detection signals to the lens side control unit 330. The acceleration sensor 390b is also called a G sensor. The shake sensor 390 may be disposed in the camera body 2. Both the angular velocity sensor 390a and the acceleration sensor 390d may be disposed in the camera body 2, or one of them may be disposed in the camera body 2 and the other in the interchangeable lens 3.

[0082] The camera system 1 is configured to be capable of performing shake correction by driving the shake correction lens 361b with the lens driving unit 370b, and by driving the image sensor 260 with the sensor driving unit 265. Therefore, for example, shake correction is performed by driving the shake correction lens 361b based on a detection signal from the shake sensor 390, and shake correction is performed by driving the image sensor 260 for the amount of shake that remains (remains) even after shake correction by the shake correction lens 361b.

[0083] In general, shake occurring in the camera system 1 can be divided into angular shake accompanying the rotational movement of the camera system 1 and translational shake accompanying the translational movement of the camera system 1. Based on the detection signal of the shake sensor 390, the lens side control unit 330 calculates each of the angular shake and the translational shake. The lens side control unit 330 calculates the angular shake in the Y axis direction due to the rotational motion, for example, using a detection signal from the angular velocity sensor 390a about an axis parallel to the X axis (pitch direction). The lens side control unit 330 also calculates the angular shake in the X axis direction due to the rotational motion, using a detection signal from the angular velocity sensor 390a about an axis parallel to the Y axis (yaw direction).

[0084] Furthermore, the lens side control unit 330 calculates the translational shake in the X-axis direction due to the translational motion using the detection signal in the X-axis direction by the acceleration sensor 390b. Also, the lens side control unit 330 calculates the translational shake in the Y-axis direction due to the translational motion using the detection signal in the Y-axis direction by the acceleration sensor 390b.

[0085] Then, the lens side control unit 330 adds up the angular shake in the X-axis direction and the Y-axis direction and the translational shake in the X-axis direction and the Y-axis direction for each X-axis and Y-axis to calculate the total shake amount in the X-axis direction and the Y-axis direction. For example, if the angular shake and translational shake calculated for a certain axis direction have the same direction, the total shake amount becomes larger as a result of the addition, but if the calculated two shake directions are different (there is a component in the opposite direction), the total shake amount becomes smaller as a result of the addition. In this way, the addition calculation is performed by assigning a positive or negative sign depending on the direction of the angular shake and translational shake for each axis.

[0086] Lens side control unit 330 further calculates the imaging surface total shake amount converted into the position on imaging surface 260S of image sensor 260 for the X-axis direction and Y-axis direction, based on the summed total shake amounts in the X-axis direction and Y-axis direction, respectively.

[0087] The lens side control unit 330 calculates target positions of the shake correction lens 361b in the X-axis direction and the Y-axis direction for moving the shake correction lens 361b in a direction that cancels a shake amount of a predetermined share out of the calculated total shake amount on the imaging surface. The share is the ratio between the shake correction amount performed by the interchangeable lens 3 and the shake correction amount performed by the camera body 2.

[0088] The lens side control unit 330, which has calculated the target position of the vibration correction lens 361b, outputs a drive signal to the lens drive unit 370b to drive the vibration correction lens 361b. The lens drive unit 370b, which has received the drive signal, moves the vibration correction lens 361b in the X-axis and Y-axis directions that intersect with the optical axis O to the target position in the X-axis direction and the target position in the Y-axis direction, respectively.

[0089] On the other hand, the body side control unit 230 calculates target positions for the image sensor 260 in the X-axis direction and the Y-axis direction to move the image sensor 260 in a direction that cancels out the shake amount of the above-mentioned share of the total image sensing surface shake amount received by the body side communication unit 240 through communication.

[0090] The body side control unit 230, which has calculated the target position of the image sensor 260, outputs a drive signal to the sensor drive unit 265 to drive the image sensor 260. The sensor drive unit 265, which has received the drive signal, moves the image sensor 260 in the X-axis and Y-axis directions intersecting with the optical axis O to the target position in the X-axis direction and the target position in the Y-axis direction, respectively. In the above, the result of adding up the angular shake and translational shake is divided into the amount of shake correction performed by the interchangeable lens 3 and the amount of shake correction performed by the camera body 2, but for example, shake correction for angular shake may be performed by the interchangeable lens 3 (lens side control unit 330) and shake correction for translational shake may be performed by the camera body 2 (body side control unit 230).

[0091] <Changes when stabilizing> When the movement direction of the image sensor 260 moved by the sensor driving unit 265 has a Y-axis component, the relative positional relationship between the image sensor 260 and the shutter unit 255 in the Y-axis direction changes because the shutter device 255 is fixed to the camera body. That is, the image sensor 260 moves in the Y-axis direction for shake correction, and the relative position of the image sensor 260 changes with respect to the traveling shutter curtains 255a and 255b. When focusing on the rear curtain 255b, the above-mentioned rear curtain first time and rear curtain second time change. Therefore, the body side control unit 230 corrects the lengths of the rear curtain first time and rear curtain second time as follows, based on the calculated Y-axis component of the target position of the image sensor 260.

[0092] For example, when the direction in which the rear curtain 255b travels is the same as the direction in which the image sensor 260 moves for shake correction (when the image sensor 260 moves in the negative direction of the Y axis), the travel speed of the rear curtain 255b relative to the image sensor 260 decreases relatively. In this case, the body side control unit 230 corrects both the rear curtain first time and the rear curtain second time to be longer as the travel speed of the rear curtain 255b relative to the image sensor 260 decreases. With this configuration, when the sensor drive unit 265 that performs shake correction moves the image sensor 260 in the same direction as the travel direction of the rear curtain 255b, the body side control unit 230 can appropriately determine the exposure timing of the focus detection pixels in consideration of the decrease in the travel speed of the rear curtain 255b relative to the image sensor 260.

[0093] In addition, by appropriately determining the exposure timing of the focus detection pixels taking into account the decrease in the travel speed of the rear curtain 255b relative to the image sensor 260 due to the above-mentioned shake correction, the signal processing unit 270 can appropriately calculate the amount of movement of the focus lens 361a to the in-focus position, starting from the average position of the focus lens 361a during the exposure time (charge accumulation time) during which the focus detection pixel signal was acquired.

[0094] Unlike the above, when the direction in which the rear curtain 255b travels is opposite to the direction in which the image sensor 260 moves for shake correction (when the image sensor 260 moves in the + direction of the Y axis), the travel speed of the rear curtain 255b relative to the image sensor 260 increases relatively. In this case, the body side control unit 230 corrects both the rear curtain first time and the rear curtain second time to be shorter as the travel speed of the rear curtain 255b relative to the image sensor 260 increases. With this configuration, when the sensor drive unit 265 that performs shake correction moves the image sensor 260 in the direction opposite to the travel direction of the rear curtain 255b, the body side control unit 230 can appropriately determine the exposure timing of the focus detection pixels in consideration of the increase in the travel speed of the rear curtain 255b relative to the image sensor 260.

[0095] In addition, by appropriately determining the exposure timing of the focus detection pixels taking into account the increase in the travel speed of the rear curtain 255b relative to the image sensor 260 due to the above-mentioned shake correction, the signal processing unit 270 can appropriately calculate the amount of movement of the focus lens 361a to the in-focus position, starting from the average position of the focus lens 361a during the exposure time (charge accumulation time) during which the focus detection pixel signal was acquired. In the above second embodiment, an example has been given of shake correction performed by driving the shake correction lens 361b by the lens driving unit 370b and shake correction performed by driving the image sensor 260 by the sensor driving unit 265, but shake correction may be performed only by driving the image sensor 260. In other words, the interchangeable lens 3 may not include the shake correction lens 361b, and shake correction may be performed by driving the image sensor 260 by the sensor driving unit 265 in response to an instruction from the body side control unit 230.

[0096] The focus detection device according to the second embodiment described above has the same effects as the first embodiment, and in addition thereto, the following effects are obtained: The focus detection device has a sensor driving unit 265 that drives the image sensor 260 and a sensor driving unit 265 that detects the position of the image sensor 260, and the body side control unit 230 uses the position detected by the sensor driving unit 265 to determine the light blocking time. With this configuration, even if the travel speed of the rear curtain 255b of the shutter device 255 changes relatively to the image sensor 260, the body side control unit 230 can appropriately determine the light blocking time of the focus detection pixels by taking into account the change in the relative travel speed of the rear curtain 255b. As a result, the signal processing unit 270 can appropriately calculate the movement amount of the focus lens 361a to the in-focus position starting from the average position of the focus lens 361a during the actual charge accumulation time.

[0097] (Variation 1) In the above description, the shutter device 255 having the front curtain 255a and the rear curtain 255b has been described as an example, but the front curtain 255a may be omitted and a shutter device having only the rear curtain 255b may be provided. The body side control unit 230 causes the image sensor 260 to start a charge accumulation operation by electronic shutter control, and then drives the shutter device 255 to close. The body side control unit 230 causes the signal processing unit 270 to perform focus detection calculation based on the focus detection pixel signals transferred from the image sensor 260 to the signal processing unit 270.

[0098] In the case of variant example 1, the time at which charge accumulation operation is started by electronic shutter control for the focus detection pixels located at the position of the frame PS corresponding to the adopted focus area P corresponds to the accumulation start time calculated in the above-described embodiment. That is, when calculating the exposure timing of frame PS51, time tb1, which is the accumulation end time at the position of frame PS51, is calculated as the accumulation start time. Furthermore, when calculating the exposure timing for frame PS52, time t3, which is the accumulation end time at the position of frame PS52, is calculated as the accumulation start time. Furthermore, when calculating the exposure timing for frame PS53, time tb3, which is the accumulation end time at the position of frame PS53, is calculated as the accumulation start time, by calculating time tb3 going back in accumulation time from time tb4.

[0099] (Variation 2) When continuously shooting a scene in which a moving main subject approaches the camera system 1, the body side control unit 230 may predict the position of the focus lens 361 based on the calculation results of the defocus amount for multiple frames. Fig. 11 is a timing chart explaining the AF operation performed during continuous shooting. Compared to the timing chart of Fig. 6, it is the same as Fig. 6 except that the position of the focus lens is different. The body side control unit 230 instructs the interchangeable lens 3 to drive the focus for each frame based on the focus detection calculation results calculated by the signal processing unit 270 for each frame.

[0100] When the defocus amount calculated based on the focus detection pixel signal acquired when capturing the previous frame increases from n-1 frame to n frame to n+1 frame, the body side control unit 230 predicts the movement amount of the focus lens 361a to the in-focus position, for example, based on the rate of increase in the defocus amount for the past multiple frames. When the target position of the focus lens 361a is calculated based on the focus detection pixel signal acquired when capturing the n+1th frame, the target position is usually set to Q1, but in the second modification, the target position is set to Q2 taking into account the rate of increase in the defocus amount. By configuring in this way, when a fast-moving main subject is continuously captured, the main subject can be kept in focus. Note that when continuously capturing a scene in which a moving main subject is moving away from the camera system 1, the body side control unit 230 may predict the position of the focus lens 361 based on the calculation results of the defocus amount for multiple frames in the same manner as described above.

[0101] When calculating the amount of movement of the focus lens 361a while predicting changes in the defocus amount as in Modification 2, if the average position of the focus lens 361a during the accumulation period is incorrect, it is difficult to maintain focus. However, since the body side control unit 230 calculates the average position based on the exposure timing calculated in the above embodiment and the position information of the focus lens 361a transmitted from the lens side control unit 330, it is possible to correctly determine the average position of the focus lens 361a during the accumulation period, which is also suitable for calculating the amount of movement of the focus lens 361a while predicting changes in the defocus amount.

[0102] According to the second modification, the following advantageous effects can be obtained: Since the position of the focus lens is predicted based on a plurality of calculation results, for example, when continuously shooting a fast-moving main subject, it is possible to keep the main subject in focus.

[0103] (Variation 3) The above-described embodiment has been described by way of example with respect to a case where position information of focus lens 361a can be obtained during charge accumulation in image sensor 260. When position information of focus lens 361a during charge accumulation cannot be obtained, the amount of movement of focus lens 361a to the in-focus position may be calculated using the most recent position information obtained before charge accumulation or the most recent position information obtained after charge accumulation as a starting point. Alternatively, a weighted average of the most recent position information acquired before and after charge accumulation may be calculated, and the amount of movement of the focus lens 361a to the in-focus position may be calculated using the weighted average position information as a starting point.

[0104] (Variation 4) In the above-described embodiment, an example has been described in which focus detection pixel signals are acquired (charge is accumulated) while the focus lens 361a is moving, but the focusing lens 361a may be stopped and not moved during charge accumulation.

[0105] The present invention is not limited to the above-mentioned contents. Other embodiments conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention. [Explanation of symbols]

[0106] 1...camera system, 2...camera body, 3...interchangeable lens, 230...body side control unit, 235...storage unit, 240...body side communication unit, 255...shutter device, 255a...front curtain, 255b...rear curtain, 260...image sensor, 265...sensor drive unit, 270...signal processing unit, 330...lens side control unit, 340...lens side communication unit, 350...lens side memory unit, 360...imaging optical system, 370...lens drive unit, P...focus area,

Claims

1. an imaging unit having a plurality of pixels that photoelectrically converts light that has passed through an optical system including a focus lens, accumulates electric charges, and outputs a signal used for focus detection, and captures an object image formed by a light beam that has passed through the optical system; a defocus calculation unit that calculates a defocus amount, which is a deviation amount between a position of the object image and a position of an imaging surface of the imaging unit, based on the signal; a shutter curtain disposed between the optical system and the imaging unit, the shutter curtain moving to control incidence of the light beam on the imaging surface; A storage unit that stores the running characteristics of the shutter curtain; a timing calculation unit that calculates an accumulation timing at which the pixel corresponding to the at least one focus area accumulates charge based on position information of at least one focus area selected from a plurality of focus areas and the travel characteristics of the shutter curtain stored in the storage unit; an acquisition unit that acquires position information of the focus lens; a calculation unit that calculates a drive amount of the focus lens based on the position of the focus lens at the accumulation timing calculated by the timing calculation unit and the defocus amount calculated by the defocus calculation unit; A focus detection device having a focus detection function.

2. 2. The focus detection device according to claim 1, A focus detection device, wherein the travel characteristic of the shutter curtain is nonlinear.

3. 3. The focus detection device according to claim 1, A focus detection device, wherein the travel characteristic of the shutter curtain is a movement speed of the shutter curtain.

4. 4. The focus detection device according to claim 1, The timing calculation unit calculates the accumulation timing based on information about an exit pupil distance of the optical system.

5. 5. The focus detection device according to claim 1, A drive unit that drives the imaging unit; a detection unit that detects a position of the imaging unit, The timing calculation unit controls the accumulation timing based on the position of the imaging unit detected by the detection unit.

6. 6. The focus detection device according to claim 1, The focus detection device, wherein, during the accumulation timing, the pixel corresponding to the at least one focus area accumulates charge while the focus lens is moving.

7. 7. The focus detection device according to claim 1, the acquisition unit acquires the position information of the focus lens at predetermined time intervals; The calculation unit calculates the position of the focus lens at the accumulation timing based on the multiple pieces of position information of the focus lens.

Images